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The algal-bacterial granular sludge (ABGS) system is emerging as a promising technology for future wastewater treatment. This study assessed the impact of different algae species inoculation on granulation, performance, and microbial communities within ABGS systems. The experimental setup included single-species inoculations (Chlorella sp. (R1), Scenedesmus sp. (R2), and Desmodesmus sp. (R3)) and a mixed-species inoculation strategy (R4). Results revealed that R4 achieved the fastest completed granulation process (15 days) with the largest average granule diameter (772.93 μm) and highest physical strength (2.24 ± 0.26%) in the end of the experiment. The relative abundance of extracellular polymeric substances secreting bacteria of R4 maintained high level in whole operation time. Algae assimilation capacity and the abundance of functional bacteria can also influence removal performance. In mature stage, only the average effluent total nitrogen (3.15 ± 2.87 mg/L), total phosphorus (0.37 ± 0.27 mg/L), chemical oxygen demand (25.25 ± 2.98 mg/L) concentration in R4 was lower than that of Grade I discharge standard of municipal wastewater treatment plants in China. The best inorganic carbon utilization and lipid production ability were observed in R4 and R3, respectively. The choice of inoculated algae species was identified as a key factor for bacterial community dynamics. Overall, above results demonstrated that mixed algae species inoculation can be selected as the optimal algae inoculation strategy due to its excellent granulation, performance, and acceptable carbon utilization and lipid production. • Mixed algae inoculation achieved fast granulation in 15 days. • Mixed algae inoculation strategy remained great granulation potential. • Succession of bacterial community can drive by algae species inoculation. • Higher lipid production can be achieved by suitable algae inoculation. [ABSTRACT FROM AUTHOR]

In this research the possibility of using a photosynthetic microbial desalination cell (PhMDC) is investigated for desalination of power plant salty wastewater (PPSWW), along with power generation and organic load removal. The PhMDC was operated with anaerobic sludge in the anode chamber, microalgae in the cathode chamber, and different conductivities of PPSWW (10, 20, 40, and 55 mS cm−1) in the desalination chamber under different illumination modes (continuous light mode and light/dark mode). The highest power density (285.5 mW m−2), desalination efficiency (60.9%), and COD removal (74.8%) was achieved at conductivity of 55 mS cm−1 under continuous light mode. The highest algal growth (900 mg. L−1) was also observed at this conductivity. The applied system demonstrated effective removal of different presented cations and anions in PPSWW with removal efficiencies of more than 58%. Dynamic shift of microbial community in the anode chamber showed notable increase in sulfate-reducing bacteria and some specific genera such as Desulfovibrio , Pseudomonas , Rhodobacter , Rhodopseudomonas , and Desulfuromonas due to their potential for electricity generation and adaptation to saline and acidic conditions. [Display omitted] • Algae-based microbial desalination cell, desalinated industrial salty wastewater. • More than 58% of different ions in power plant salty wastewater were removed. • The maximum power density was 285.5 mW m−2 at salinity of 55 mS cm−1 • Total desalination efficiency of 60.9% and COD removal of 74.8% was achieved. • Specific exoelectrogens and sulfate-reducing bacteria dominated in anodic culture. [ABSTRACT FROM AUTHOR]

The inclusion of carbohydrate-rich ingredients in aquafeeds has resulted in an increased fraction of undigested material, culminating in faecal waste enriched in unutilized nutrients containing carbon, nitrogen and phosphorus. This study explored the impact of faecal composition, as influenced by diet, on the products of anaerobic digestion with a focus on organic acids (OAs). The aim was to in vitro assess the potential of faeces as internal carbon for denitrification, promoting circularity in recirculating aquaculture systems. In this regard, settleable faeces originating from six diets (DDGS, Dried distillers' grains with solubles; HFM, Hydrolyzed feather meal; IM, Insect meal; SCP, Single-cell protein; SSM, Shrimp shell meal; SWP, Seaweed protein) fed to European seabass, were incubated for a 14-day period in anoxic batch reactors. Nutrient solubilization (chemical oxygen demand, total Kjeldhal nitrogen, total phosphorus) was measured over time, and the final yield of OA was studied in relation to prokaryotic community composition. Results showed that digestion of faecal waste with a high crude-protein-to-carbohydrate ratio leads to an increased amount of OA which is greatly dominated by acetate. Among them, SSM faeces exhibited the highest final OA yield, resulting from a continuous increase over time. Despite variations in OA quantity and profile, prokaryotic composition did not substantially differ among treatments at the end of the trial, with only the relative abundance of three genera varying significantly (Anaerostignum , Bythopirellula , Mycobacterium). Yet, lactate concentration positively correlated with several taxa (Trichococcus , Oleispira , Defluviitaleaceae , Anaerocolumna , and Carboxyliverga) and butyrate with Anaerostignum. Alongside, ammonia release was minimal for all treatments, while phosphorus dissolution did not correlate to the faecal phosphorus content but was rather a result of acidification due to OA production. Overall, considering that an optimal carbon source for denitrification should produce a high amount of end OAs (i.e. acetate) along with low dissolved nitrogen and phosphorus, this research suggests that faecal waste originating from certain carbohydrate-rich aquafeed ingredients can be suitable as internal carbon source for denitrification. [Display omitted] • Digesting protein-rich waste yields more organic acids and higher acetate levels. • Prolonged digestion of carbohydrate-rich waste does not improve organic acid yield. • Organic acid profile differs with faecal composition after a 14-day digestion time. • Similar prokaryotic compositions drive digestion regardless of faecal composition. • Nitrogen and phosphorus release can be independent of faecal composition. [ABSTRACT FROM AUTHOR]

Municipal wastewater (MW) and industrial wastewater from juice processing (IWJ) were blended in different proportions to assess the effect of the carbon/nitrogen (C/N) ratio on pollutant removal, microalgal biomass (MB) cultivation, and the accumulation of carotenoids and biocompounds. MB development was not observed in treatments with higher C/N ratios (>30.67). The wastewater mixture favored the removal of dissolved organic carbon (75.61 and 81.90%) and soluble chemical oxygen demand (66.78–88.85%), compared to the treatment composed exclusively of MW (T7). Treatments T3 and T6 (C/N ratio equal to 30.67 and 7.52, respectively) showed higher Chlorophyll- a concentrations, 1.47 and 1.54 times higher than T7 (C/N ratio 1.75). It was also observed that the C/N ratio of 30.67 favored the accumulation of carbohydrates and lipids (30.07% and 26.39%, respectively), while the C/N ratio of 7.52 improved protein accumulation (33.00%). The fatty acids C16:0, C18:1, C18:2, and C18:3 had the highest concentrations. Additionally, increasing the C/N ratio can be an efficient strategy to improve the production of fatty acids for biofuels, mainly due to the increased concentration of shorter-chain fatty acids (C16:0). These findings suggest that blending wastewater not only enhances treatment performance but also increases the accumulation of valuable carbohydrates and lipids in MB, and optimizes fatty acid production for biofuel applications. This research represents significant progress towards feasibility of using MB produced from wastewater. [Display omitted] • Municipal and industrial wastewater were blended to assess different C/N ratios. • The blend favored C removal, with 81.90% for DOC and 88.85% for SCOD. • T3 (C/N = 30.67) favored carbohydrate (30.07%) and lipid accumulation (26.39%). • The highest protein content (33.00%) was achieved at a C/N ratio of 7.52. • T3 exhibited peak levels of beta-carotene (13.55 μg g−1) and lutein (537.59 μg g−1). [ABSTRACT FROM AUTHOR]

Microbial fuel cell (MFC) is a variant of the bio-electro-chemical system that uses microorganisms as biocatalysts to generate bioenergy by oxidizing organic matter. Due to its two-prong feature of simultaneously treating wastewater and generating electricity, it has drawn extensive interest by scientific communities around the world. However, the pollution purifying capacity and power production of MFC at the laboratory scale have tended to remain steady, and there have been no reports of a performance breakthrough. This research was conducted to produce electricity and evaluate the efficiency of chemical oxygen demand (COD) removal from wastewater containing Citric Acid using a two-chamber microbial fuel cell without an intermediary. In this research, citric acid factory wastewater was used as the substrate, graphite as the electrode, Nafion membrane for proton transfer from anode to cathode, and grape waste as a carbon source. These Experiments were performed at room temperature and neutral pH. Also, the effect of three independent variables mixed liquor suspended solid (MLSS), Carbon: Nitrogen: Phosphorus stoichiometric ratio (COD:TKN:P), and grape waste on electricity production and wastewater treatment was investigated. Then, the optimal values of each variable were determined under favorable conditions for electricity generation and COD reduction. The MFC was conducted at the optimal values of MLSS 1400 mg/L, the stoichiometric ratio of COD:TKN:P 140:10:1, and the grape waste dose of 1.4 g/L. At these conditions, the obtained maximum power density and current density were 18228.10 µW/m2 and 244.44 mA/m2, respectively. The maximum COD removal was 72% achieved in the values of MLSS 1400 mg/L, the stoichiometric ratio of COD:TKN:P equal to 260:10:1, and 1.4 g/L of grape waste. The maximum open circuit voltage was also recorded as 678 mV, obtained at MLSS 3000 mg/L, the stoichiometric ratio of COD:TKN:P equal to 200:10:1, and for a grape waste dose of 2 g/L. The results of this research showed that the use of grape waste to supply glucose to microorganisms in the MFC system has a significant effect on increasing energy production and COD removal, and it is recommended to conduct additional research in the future to improve the efficiency. However, scalability and practical application potential of these integrated technologies are the challenges towards their real-world applications in small scale trials. • Electricity generation and COD reduction of acid citric wastewater were optimized. • The stoichiometric ratio of COD:TKN:P achieved 140:10:1 for the high performance. • The maximum power and current density recorded as 18228 µW/m2 and 244 mA/m2. • The process achieved 72% COD removal from the wastewater. [ABSTRACT FROM AUTHOR]

Water scarcity has generated the need to identify new sources. Due to its low organic contaminant load, greywater reuse has emerged as a potential alternative. Moreover, the search for decentralized treatment systems in urban areas has prompted research on using green roofs for greywater treatment. However, the performance of organic matter removal is limited by the type of substrate and height of the growing media. Bioelectrochemical systems (BESs) improve treatment performance by providing an additional electron acceptor (the electrode). In this study, nine reactors under three different conditions, i.e., open circuit (OC), microbial fuel cell (MFC), and microbial electrolysis cell (MEC), were built to evaluate the treatment of synthetic greywater in a substrate-growing medium composed of perlite and coconut fiber and operated in batch-cycle mode for 397 days. The results suggested that using BESs enables greywater treatment and the removal of pollutants to levels that allow their reuse for irrigation. Furthermore, electrical conductivity was reduced from 732.4 ± 41.2 μS/cm2 in OC to 637.32 ± 22.73 μS/cm2 and 543.15 ± 19.69 μS/cm2 in MEC and MFC, respectively. The soluble chemical oxygen demand in the latter treatments reached 76% removal, compared to levels above the OC, which only reached approximately 67%. Microbial community analysis revealed differences, mainly in the cathodes, showing a higher development of Flavobacterium , Azospirillum , and Zoogloea in MFCs, which could explain the higher levels of organic matter removal in the other conditions, suggesting that the BES could produce an enrichment of beneficial bacterial groups for treatment. Therefore, implementing BESs in green roofs enables sustainable long-term greywater treatment. [Display omitted] • The substrate depth is a relevant factor in greywater treatment on green roofs. • Bioelectrochemical systems in a low-height substrate enhance greywater treatment. • Long-term organic matter removal was improved and 90% of surfactants was removed. • Electrical conductivity was reduced in bioelectrochemical systems. • Bioelectrochemical systems enriched organic matter degrading bacterial groups. [ABSTRACT FROM AUTHOR]

The coexistence of oxygen and/or nitrate at anode usually affects the biofilm activities of traditional anaerobic anode, thereby deteriorating wastewater treatment performance of microbial fuel cells (MFCs). Improving the aerotolerant responses of anode biofilms is a challenge for field application. In this study, we report that using the electroactive nitrifying/denitrifying inoculum and air-cathode expansion could fabricate the aerotolerant anode biofilms (AAB) under affordable nitrate stress (90 ± 5 mg/L). The highest average removal efficiencies were 99% for chemical oxygen demand (COD), NH 4 +-N and total nitrogen. The highest average current output of 0.69 mA and power density of 290 mW/m2 were obtained. The average current was confirmed to be reduced 10%–78% but the power density remained almost stable except the quart-air-cathodes MFC by increasing dissolved oxygen concentration with expansion of the air-cathode area. The higher oxygen concentration also contributed to oxidation of ammonium through electroactive autotrophic nitrification. The facultative anaerobic bacteria including Thauera , Microsillaceae , Shinella , Blastocatellaceae , Rhodobacter , Comamonadaceae , Caldilineaceae were enriched, which forms the AAB to remove nitrogen and produce current. Therefore, an easy-to-use method to fabricate AAB is evaluated to realize practical applications of MFCs in wastewater treatment. [Display omitted] • Aerotolerant anodes are fabricated in coexisting oxygen and affordable nitrate. • Currents are generated by aerotolerant anodes under high DO condition. • Aerotolerant anodes achieve efficient nitrogen removal and power recovery. • Increasing air-cathodes can enhance aerobic environment around the anodes. [ABSTRACT FROM AUTHOR]

The aim of the study was to efficiently treat organic kitchen waste (FW) and domestic wastewater (DWW) together in an anaerobic fluidized bed bioreactor equipped with a ceramic membrane (AnFCMBR) through a sustainable approach considering energy recovery. The system operated continuously for 519 days at room temperature, and different filtration fluxes (1.7 and 5 L/m2/h), hydraulic retention times (HRTs) (22 h and 7 h), and organic loading rate (OLRs) (0.46, 1.52, 3.42, 6.08 kg/m3.d) were tested. The amount of organic matter in DWW may be insufficient for feasible gas production, but this challenge can be resolved through the addition of food waste. Influent chemical oxygen demand (COD) of 500 ± 143 mg/L gradually increased to 2000 ± 196 mg/L by increasing the portion of FW. The COD removal ranged from 92 to 98% throughout the study, with the membrane and the cake layer contributing 5–8% to the performance. Average supernatant SMP and EPS concentrations increased from 5 ± 1 to 45 ± 5 mg COD/L and from 54 ± 7 to 254 ± 26 mg COD/g VSS, respectively, when the highest amount of FW was added to the synthetic wastewater. This significant increase in SMP and EPS concentrations due to the addition of FW negatively impacted the filtration performance. SRF and CST values also increased with rising OLR, especially with the supplementation of synthetic wastewater with FW. After FW started to be mixed with DWW, the methane production increased approximately 5.5 times. With the use of AnFCMBR for the co-treatment of FW and DWW, it is possible to achieve energy-positive treatment with high-quality effluent that can be reused for various applications, such as irrigation. The methane produced provided 12 times more energy than was needed to operate the bioreactor. This is the first study evaluating the co-treatment of FW and DWW in AnFCMBR under varying operational parameters. • A 7.5 h HRT gave average soluble COD of 28 mg/L in permeate. • Methane production increased by 5.5 times with the supplementation of FW. • Methane energy potential was 12 times greater than needed for operation energy. • In-situ chemical cleaning did not have adverse effect on performance. [ABSTRACT FROM AUTHOR]

Regarding curtailing carbon emissions in wastewater treatment, the high-rate contact stabilization (HiCS) process outperforms others in removing dissolved organic matter (DOM) but struggles with poor settling performance. To boost operation performance and clarify the correlation between process parameters, DOM variations, effluent quality, and microbial metabolism within the HiCS system, the impacts of sludge properties on sludge settlement and organic matter (OM) capture efficiency were explored, and soluble fluorescent components in the DOM and extracellular polymeric substances (EPS) were identified and scrutinized. Results unveil that the feast/famine (F/F) regime in the HiCS process predominantly governs sludge activation in the stabilization phase, influencing sludge properties such as morphology characteristics, biological activity, and EPS secretion. At the same hydraulic retention time, reducing the sludge retention time (SRT) led to looser and smaller activated sludge flocs, increased microbial activity, and higher EPS production, particularly protein content in loosely bound EPS (LB-PN), which adversely impacted settling performance. High-throughput sequencing revealed that richness and diversity of the microbial community decreased with SRT. Acidobacteriota and Patescibacteria , associated with nitrifying and denitrifying bacteria, significantly decreased. EPS-producing Firmicutes increased, enhancing EPS secretion, while filamentous Chloroflexi decreased, aligning with a reduced organic mineralization rate. Settlement and biological activity emerged as key factors affecting OM recovery, peaking at 43.97% with a 4-day SRT. The ratio of the sum of tryptophan-like and tyrosine-like components to fulvic-like components ((C1+C2)/C3) was proposed as a fluorescence indicator, serving as a hub to connect operational parameters, F/F regime, sludge status and process performance. When this ratio falls within the range of 1.04–1.36 during the stabilization phase, HiCS sludge achieves optimal status for OM capture with low aeration energy consumption. [Display omitted] • Feast/famine regime of HiCS governs sludge activation, impacting sludge properties. • Poor settling performance of HiCS significantly correlates with protein in LB-EPS. • COD recovery peaked at 43.97%, depending on settlement and biological activity. • (C1+C2)/C3 ratio is a fluorescent index to optimize sludge status for COD capture. [ABSTRACT FROM AUTHOR]

High-salt textile dyeing wastewater is difficult to treat. Magnetic fields can enhance the biodegradation capacity and extreme environmental adaptabilities of microorganisms. Thus, magnetically enhanced bioreactors are expected to improve the treatment efficiency and stability of high-salt textile dyeing wastewater. Accordingly, a novel Built-in Static Magnetic Field – Biological Aerated Filter (BSMF–BAF) was constructed and investigated for treating actual high-salt textile dyeing wastewater in this study. Two other BAFs packed with traditional and magnetic ceramsite carriers, respectively, were simultaneously operated for comparison. The removal of color, chemical oxygen demand (COD), suspended solid (SS) and acute toxicity were monitored. The activities of key enzymes and microbial community structure were analyzed to reveal possible mechanisms for improving the treatment efficiency of traditional BAF using the BSMF. The results showed that the BSMF–BAF possessed the highest removal efficiencies of color, COD, SS and acute toxicity among the three BAFs. The BSMF induced significant increases in the activities of azoreductase and lignin peroxidase, which were responsible for the degradation of azo compounds in the wastewater and the detoxification of toxic intermediates, respectively. Additionally, the BSMF induced the relative enrichment of potentially effective bacteria and fungi, and it maintained a relatively high abundance of fungi in the microbial community, resulting in a high treatment efficiency. [Display omitted] • Built-in static magnetic field biological aerated filter was proposed. • Effectiveness of the BSMF – BAF was evaluated with actual textile dyeing wastewater. • Activity of key enzymes responsible for detoxification was promoted by the BSMF. • Potentially effective bacteria and fungi were selectively enriched in the BSMF – BAF. [ABSTRACT FROM AUTHOR]

To improve the treatment performance of constructed wetlands under low-temperature conditions, this study investigated the effects of plant species on wastewater treatment performance at low temperature and the associated microbiological characteristics in a subsurface vertical-flow constructed wetland (VFCW) with step-feeding. The results showed that the redox microenvironment in the VFCW filter with step-feeding could be restored and optimized by planting appropriate species that can tolerate low temperature, ensuring a high nitrification performance for the system. Correspondingly, the abundance and activity of three functional microbes (namely nitrifiers, denitrifiers, and anammox bacteria) increased to different degrees in the system, eventually ensuring ideal nitrogen removal by the VFCW. Compared with the VFCW planted with Phragmites australis and Acorus gramineus , the operation performance of the VFCW planted with Iris wilsonii could be recovered at low temperature, and its chemical oxygen demand, total phosphorus, total nitrogen, and ammonium nitrate removal rates could respectively reach 95.7%, 99.2%, 93.0%, and 94.4%, respectively. Moreover, nitrogen removal in the system relied on the nitrification/denitrification and partial denitrification - anaerobic ammonium oxidation processes. Nitrosomonas , Nitrospira , Thauera , and Candidatus Brocadia were the four dominant bacterial genera in the filter layer. [Display omitted] • Plant species affected N transformation in step-feeding VFCW at low temperature. • Suitable hardy plant enhanced nitrification/denitrification and PD/AMX in the VFCW. • Step-feeding using domestic sewage as external carbon source enhanced denitrification. • Iris Wilsonii planted in VFCW achieved high rate of N removal. • Key bacterial genera in filter: Nitrosomonas , Nitrospira , and Thauera. [ABSTRACT FROM AUTHOR]

The production of short-chain fatty acids (SCFAs) through anaerobic fermentation of waste activated sludge (WAS) is commonly constrained by limited substrate availability, particularly for WAS with low organic content. Combining the hydrocyclone (HC) selection with alkali-thermal (AT) pretreatment is a promising solution to address this limitation. The results indicated that HC selection modified the sludge properties by enhancing the ratio of mixed liquid volatile suspended solids (MLVSS)/mixed liquid suspended solids (MLSS) by 19.0% and decreasing the mean particle size by 17.4%, which were beneficial for the subsequent anaerobic fermentation process. Under the optimal HC + AT condition, the peak value of SCFAs production reached 4951.9 mg COD/L, representing a 23.2% increase compared to the raw sludge with only AT pretreatment. Mechanism investigations revealed such enhancement beyond mechanical separation. It involved an increase in bound extracellular polymeric substances (EPS) through HC selection and the disruption of sludge spatial structure by AT pretreatment. Consequently, this combination pretreatment accelerated the transfer of particulate organics (i.e., bound EPS and intracellular components) to the supernatant, thus increasing the accessibility of WAS substrate to hydrolytic and acidifying bacteria. Furthermore, the microbial structure was altered with the enrichment of key functional microorganisms, probably due to the facilitation of substrate biotransformation and product output. Meanwhile, the activity of hydrolases and SCFAs-forming enzymes increased, while that of methanogenic enzymes decreased. Overall, this strategy successfully enhanced SCFAs production from WAS while reducing the environmental risks of WAS disposal. [Display omitted] • Hydrocyclone can select the sludge with higher organics and smaller particle size. • The effect of HC with AT pretreatment on anaerobic WAS fermentation was evaluated. • The maximum accumulation of SCFAs reached 4951.9 mg COD/L on day 4. • Organics in WAS and biodegradability of released organics were promoted. • Microbial community ameliorated under optimal HC with AT pretreatment condition. [ABSTRACT FROM AUTHOR]

This study evaluated anaerobic co-digestion as a promising strategy for managing organic-contaminated waste streams generated from nanomaterial synthesis. The novel approach enabled precise quantification of organic content, efficient biomethane recovery, and a sustainable redirection of ethanol-contaminated graphene oxide (GO) dispersions. The proposed method achieved high accuracy (93–97%) in detecting organic content in ethanol-contaminated GO dispersions, significantly outperforming the conventional total chemical oxygen demand (tCOD) method, which only reached 75–77% accuracy. Additionally, co-digestion of trace ethanol content in GO dispersions with municipal sludge substantially enhanced methane production kinetics, resulting in a 17.6% increase in specific methane yield (per tCOD added) and a 284% increase in total methane production. Parallel anaerobic digestion (AD) experiments using conductive GO nanosheets (without ethanol) revealed the synergistic impact of GO nanosheets and trace ethanol content as a key mechanism driving these improvements. Furthermore, the study provided evidence of the biological reduction of GO and its magnetite-decorated counterpart, magnetic GO, as indicated by a shift in the I D /I G ratio from 1.06 to 0.77 and a G-band shift from 1606 cm⁻1–1565 cm⁻1. This reduction decreased the stability of nanosheets in the AD liquid phase, promoting their partitioning into the solid phase. This process facilitates the adsorption of the GO phase within the digestate and allows for the slow release of micronutrients when used as soil amendments. [Display omitted] • Organic contaminated GO prevails in waste streams, with unknown toxicological risks. • Anaerobic digestion hits 93–97% organic quant accuracy, passing traditional methods. • Co-digesting ethanol-contaminated GO with municipal sludge boosts methane by 17.6%. • Synergistic GO nanosheets and ethanol enhance methane kinetics of municipal sludge. • Raman reveals biological reduction of GO and its partition with biosolids phase. [ABSTRACT FROM AUTHOR]

Microbial Fuel Cells (MFCs) are a sophisticated and advanced system that uses exoelectrogenic microorganisms to generate bioenergy. Predicting performance outcomes under experimental settings is challenging due to the intricate interactions that occur in mixed-species bioelectrochemical reactors like MFCs. One of the key factors that limit the MFC's performance is the presence of a microbial consortium. Traditionally, multiple microbial consortia are implemented in MFCs to determine the best consortium. This approach is laborious, inefficient, and wasteful of time and resources. The increase in the availability of soft computational techniques has allowed for the development of alternative strategies like artificial intelligence (AI) despite the fact that a direct correlation between microbial strain, microbial consortium, and MFC performance has yet to be established. In this work, a novel generic AI model based on subspace k-Nearest Neighbour (SS-kNN) is developed to identify and forecast the best microbial consortium from the constituent microbes. The SS-kNN model is trained with thirty-five different microbial consortia sharing different effluent properties. Chemical oxygen demand (COD) reduction, voltage generation, exopolysaccharide (EPS) production, and standard deviation (SD) of voltage generation are used as input features to train the SS-kNN model. The proposed SS-kNN model offers an accuracy of 100% during training period and 85.71% when it is tested with the data obtained from existing literature. The implementation of selected consortium (as predicted by SS-kNN model) improves the COD reduction capability of MFC by 15.67% than that of its constituent microbes which is experimentally verified. In addition, to prevent the effects of climate change and mitigate water pollution, the implementation of MFC technology ensures clean and green electricity. Consequently, achieving sustainable development goals (SDG) 6, 7, and 13. [Display omitted] • Novel subspace-kNN (SS-kNN) AI model proposed to predict best microbial consortium. • Developed AI model eliminates tedious task of experimental setup, saving resources. • Model tested with microbes isolated from CETP wastewater attaining 85.71% accuracy. • Outcome of SS-kNN AI model maximises the performance of MFC. • Sustainable development goals 6, 7, and 13 are achieved. [ABSTRACT FROM AUTHOR]

Anaerobic digestion provides a solution for the treatment of vegetable waste water (VWW), but there are currently limited targeted treatment methods available. Building upon previous studies, this research investigated the effects of polyacrylamide-modified magnetic micro-particles (MMP) on anaerobic digestion (AD) of VWW. Three variations of these particles were created by grafting anionic, cationic, and non-ionic polyacrylamide (PAM) onto the MMPs' surfaces, resulting in aPAM-MMP, cPAM-MMP, and nPAM-MMP, respectively. In AD experiments, the addition of aPAM-MMP notably enhanced the degradation of chemical oxygen demand (COD) in VWW. COD decreased to 1290 mg/L in the reactor with aPAM-MMP by day 12 and remained low, while the other reactors had COD concentrations of 4137.5, 5510, and 3010 mg/L on the same day, decreasing thereafter. This modification also improved the production and utilization of hydrogen gas and volatile fatty acids (VFAs), along with the conversion of methane. When tested for bioaffinity using fluorescent GFP-E.coli bacteria, the aPAM-MMP, cPAM-MMP, and nPAM-MMP demonstrated increases in fluorescence intensity by 51.66%, 36.13%, and 37.02%, respectively, compared to unmodified MMP when attached with GFP-E.coli. Further analyses of microbial community revealed that the reactor with aPAM-MMP had the highest microbial richness and enriched bacteria capable of organic matter degradation, such as Bacteroidota , Synergistota , Chloroflexi, Halobacterota phyla, and Parabacteroides , Muribaculaceae , and Azotobacter genera. In conclusion, our experiment verifies that APAM-MMP promotes anaerobic treatment of VWW and provides a novel reference point for enhancing VWW degradation. [Display omitted] • APAM modified magnetic microparticle (aPAM-MMP) enhanced anaerobic digestion. • APAM-MMP enhanced of the degradation of vegetable waste water (VWW). • VFAs production was promoted with the addition of aPAM-MMP. • Modification with PAM increased the biocompatibility of MMP. • The bacterial related to the degradation of organics were enriched with aPAM-MMP. [ABSTRACT FROM AUTHOR]

The positive contributions of carriers to aerobic granulation have been wildly appreciated. In this study, as a way resource utilization, the dredged sediment was thermally-treated to prepared as carriers to promote aerobic granular sludge (AGS) formation and stability. The system was started under low superficial gas velocity (SGV, 0.6 cm/s)for a lower energy consumption. Two sequencing batch reactors (SBR) labeled R1 (no added carriers) and R2 (carriers added), were used in the experiment. R2 had excellent performance of granulation time (shortened nearly 43%). The maximum mean particle size at the maturity stage of AGS in R2 (0.545 mm) was larger compared to R1 (0.296 mm). The sludge settling performance in R2 was better. The reactors exhibited high chemical oxygen demand (COD) and ammonia nitrogen (NH 3 -N) removal rates. The total phosphorus (TP) removal rate in R2 was higher than R1 (almost 15% higher) on stage II (93-175d). R2 had a higher microbial abundance and dominant bacteria content. The relative abundance of dominant species was mainly affected by the carrier. However, the enrichment of dominant microorganisms and the evolution of subdominant species were more influenced by the increase of SGV. The results indicated that the addition of carriers induced the secretion of extracellular polymeric substances (EPS) by microorganisms and accelerated the rapid formation of initial microbial aggregates. This work provided a low-cost method and condition to enhance aerobic granulation, which may be helpful in optimizing wastewater treatment processes. [Display omitted] • The AGS system was successfully started under low SGV (0.6 cm/s). • Thermally-treated dredged sediment was used as a carrier for resource utilization. • The carriers stimulated the secretion of EPS, shortening aerobic granulation. • Enhanced AGS exhibited greater particle size and higher microbial abundance. • The TP removal effect of the enhanced AGS system has been improved. [ABSTRACT FROM AUTHOR]

Digestates from low-tech digesters need to be post-treated to ensure their safe agricultural reuse. This study evaluated, for the first time, vermifiltration as a post-treatment for the digestate from a low-tech digester implemented in a small-scale farm, treating cattle manure and cheese whey under psychrophilic conditions. Vermifiltration performance was monitored in terms of solids, organic matter, nutrients, and pathogens removal efficiency. In addition, the growth of earthworms (Eisenia foetida) and their role in the process was evaluated. Finally, the vermicompost and the effluent of the vermifilter were characterized in order to assess their potential reuse in agriculture. Vermifilters showed high removal efficiency of chemical oxygen demand (55–90%), total solids (60–80%), ammonium nitrogen (83–97%), and phosphate-P (28–49%). Earthworms effectively grew and reproduced on digestate (i.e. earthworms number increased by 183%), enhancing the vermifiltration performance, while reducing clogging and odour-related issues. Both the vermicompost and effluent produced complied with legislation limits established for soil improvers and wastewater for fertigation, respectively. Indeed, there was an absence of pathogens and non-detectable heavy metals concentrations. Vermifiltration may be thus considered a suitable post-treatment option for the digestate from low-tech digesters, allowing for its safe agricultural reuse and boosting the circular bioeconomy in small-scale farms. [Display omitted] • Vermifiltration to enhance the safe reuse of digestate from low-tech digesters. • Vermifilters showed high removal efficiency of COD, TS, ammonium-N and phosphate-P. • Earthworms grew and reproduced on digestate enhancing vermifiltration performance. • Vermicompost and effluent can be safely reused in agriculture. • Vermifiltration boosts the circular bioeconomy in small-scale farms. [ABSTRACT FROM AUTHOR]

In this study, low-cost tubular ceramic membranes were fabricated by using waste slag and natural raw materials in order to decrease the manufacturing carbon footprints. The effects of incorporation of phosphorus slag (PS) and blast furnace slag (BFS) in the mullite-zeolite membrane body were investigated. The structural characteristics of the fabricated membranes were evaluated using X-ray diffraction (XRD), field emission–scanning electron microscopy (FESEM), atomic force microscopy (AFM), contact angle, porosity and average pore size analyses. Thermal and mechanical stability were studied by thermogravimetric analysis (TGA) and three-point bending test, respectively. The oily wastewater treatment tests revealed that an increase in the slag percentage from 0 to 30% leads to enhancing the permeate flux from 99 l m−2 h−1 to 349 l m−2 h−1 for PS-based tubular membrane and to 244 l m−2 h−1 for BFS-based tubular membrane under 1 bar applied. The chemical oxygen demand (COD) removal percentage of all membranes was reported almost 99% for oily wastewater feed with a COD concentration of 612 mg l−1. In addition, the investigation of membrane fouling mechanisms was carried out using Hermia models indicating that the best correlation with the experimental data is observed for the complete pore blocking model. This study presents experimental foundations aimed at enhancing the performance of affordable slag-based membranes, thus fostering their applicability in engineering contexts. [Display omitted] • Recycling BFS and PS waste was employed to manufacture a cost-effective tubular ceramic membrane. • The fabricated slag-based tubular ceramic membranes demonstrated a COD removal percentage of nearly 99% in oily wastewater treatment. • Raising slag percentage to 30% results in enhanced permeate flux, attributed to the formation of anorthite crystals. • The fouling mechanisms were examined through the application of Hermia models. [ABSTRACT FROM AUTHOR]

Adhesive production industry wastewater can be characterized by high chemical oxygen demand (COD) sourced from high refractory organic contaminants and high total suspended solids (TSS) concentration. Biodegradability of the wastewater is low and wastewater quality is unstable. Various treatment processes have limited applicability in such characterized wastewater. In this study, the treatment performance of electrochemical processes was investigated. Because it is not possible to meet the discharge standards by application of only one process for high refractory organic content, sequential electrochemical processes were studied in this work. In the first step of the sequential process, electrocoagulation (EC) using Al electrodes by which better performance was achieved was applied. In the second step, electrooxidation (EO) and peroxi-coagulation (PC) processes were applied to the EC effluent. In EO, Ti/MMO was selected as the most effective anode whereas in PC, Fe was used as the anode, and graphite was used as the cathode. Box-Behnken Design was applied to optimize the operating conditions of EO and PC processes and to obtain mathematical model equations. In the EC process, 77% COD, 78.5% TSS, and 85% UV 254 removal efficiency were obtained under the optimum conditions (pH 7.2, reaction time 35 min, and current density 0.5 mA/cm2). With the EO and PC processes applied to the effluent of EC, 68.5% COD, 77% TSS, and 83% UV 254 removal and 77.5% COD, 87% TSS, and 86.5% UV 254 removal were obtained, respectively. The specific energy consumption of EC-EO and EC-PC processes was 16.08 kWh/kg COD and 15.06 kWh/kg COD, respectively. Considering the treatment targets and process operating costs, it was concluded that both sequential electrochemical systems could be promising alternative systems for the treatment of adhesive production industry wastewater. [Display omitted] • Sequential configurations of EC with EO and PC were investigated. • EO and PC processes were optimized by Box-Behnken Design. • 68.5% COD, 77% TSS, and 83% UV 254 removal were obtained by EO. • 77.5% COD, 87% TSS, and 86.5% UV 254 removal were obtained by PC. [ABSTRACT FROM AUTHOR]

The anaerobic biological treatment of landfill leachate frequently encounters the souring problems because of the high concentration of organic in landfill leachate. Nonetheless, the performance of anaerobic membrane bioreactor (AnMBR) is commendable in terms of removal of organic compounds. Hence, this study explored the effect of organic concentration and hydraulic retention time(HRT) on the removal performance of actual landfill leachate, additionally, carbon conversion through carbon mass balance analysis was analyzed, in order to determine the optimal treatment potential of AnMBR in treating landfill leachate. For HRT values between 14.5 h and 34.6 h, and the influent COD (Chemical Oxygen Demand) range of 12,773.33–15706.67 mg/L, AnMBR could efficiently treat landfill leachate. As HRT was fixed at 14.5 h and influent COD was around 12,206.7–15,373.33 mg/L, AnMBR achieved a maximum organic removal rate of 18.22 ± 0.51 kg COD/(m3∙d) with methane yield of 0.24 ± 0.01 m3 CH 4 /kg COD and methane content of 88.26%. Based on carbon mass balance, increasing COD concentration in the influent (less than 16,000 mg/L) boosted the conversion of organic compounds (45.19 ± 4.24%) into CH 4 ; while decreasing HRT (more than 27.0 h) also promoted the conversion of organic compounds into CH 4 (38.36–60.93%) resulting in a decreased TOC (Total Organic Carbon) loss by 2.02–7.19% with outflow. AnMBR may efficiently produce methane while treating landfill leachate by assessing the random forest model (RF) and adjusting the balance between HRT and influent COD concentration. [Display omitted] • AnMBR achieved an average COD removal percentage of 90.87% for fresh leachate. • AnMBR achieved a maximum OLR of 21.15 kg COD/(m3∙d) at HRT of 14.5 h. • Methane yield of 0.30 m3 CH 4 /kg COD and methane content of 88.26% were obtained. • Increasing COD and decreasing HRT boosted organic compounds converted into CH 4. [ABSTRACT FROM AUTHOR]

There are a large number of simple landfills in hilly areas, and the results of previous studies have shown that pollutants in landfills can spread via interflow and cause surface source pollution. The hybrid activated sludge-membrane aerated bioreactor (H-MABR) developed in a previous study can be used for the treatment of interflow with a low chemical oxygen demand (COD)/total nitrogen (TN) ratio, and it has been shown to be effective in laboratory simulations. To investigate the effectiveness of the H-MABR in treating interflow around landfills in real-world applications, an in-situ pilot-scale evaluation of the effectiveness of H-MABR operation was conducted at a landfill. The results indicated that the removal efficiencies of COD, TN, and ammonia nitrogen in interflow by H-MABR were 87.1 ± 6.0%, 80.9 ± 7.9%, and 97.9 ± 1.4%, respectively. The removal rate of TN reached 148.6–205.6 g-N/m3·d. The concentration of each pollutant in the effluent was in accordance with China's "Standard for pollution control on the landfill site of municipal solid waste (GB16889-2008)," wherein the COD, TN, and ammonia nitrogen of effluent should be less than 100 mg/L, 40 mg/L, and 25 mg/L, respectively. The results of community composition analysis and PICRUSt analysis based on 16S rRNA gene sequencing showed that there were different dominant functional bacteria between the inner and outer rings, but functional genes involved in the nitrification-denitrification, assimilated nitrate reduction, and dissimilated nitrate reduction pathway were all detected. Furthermore, except for the nitrite oxidation gene narG , the abundance of which did not significantly differ between the inner and outer rings, the abundance of the other functional genes was higher in the outer ring than in the inner ring. An economic evaluation revealed that the operation cost of interflow treatment by the H-MABR was as low as ¥2.78/m3; thus, the H-MABR is a shock-load-resistant and cost-effective technology for interflow treatment. [Display omitted] • The performance of a H-MABR was studied under pilot-scale conditions. • The removal efficiencies of COD and TN reached 87.06 ± 6.04% and 80.86 ± 7.90%, respectively. • The TN removal rate of H-MABR reached 148.6–205.6 g-N/m3·d. • The operation costs of H-MABR were low (¥2.78/m3). [ABSTRACT FROM AUTHOR]

Commonly high lipid in food waste confronts anaerobic digestion with improved energy production and also inhibition risk from the intermediate long chain fatty acids (LCFAs). Combined with operation challenges from anaerobic digestion of food waste itself, coping strategies are necessitated to ensure stable operation for oily food waste (OFW). A parallel thermophilic (TD) and mesophilic digestion (MD) of high-solid OFW was conducted and operated continuously for a long term. It was clarified that challenges were mainly from acidification, trace metal deficiency and LCFA inhibition. Acidification resulted in an abrupt pH decline to even below 6.00, and over 75% drop of biogas production rate. In addition to the requirements of saturated strong alkali to maintain an appropriate range, supplementation of trace metals were proven effective in counteracting the sharp decrease of biogas production rate. The TD was observed more competent in coping with the acidification than the MD, while the TD needed more supplementation of trace metals at approximately 0.10 mg Fe/g chemical oxygen demand (COD) added , 0.01 mg Co/g COD added and 0.01 mg Ni/g COD added. The TD was more adaptable in LCFA conversion due to the stronger ability of overcoming the palmitic acid (C16:0) accumulation. The MD experienced a prolonged recovery period owing to LCFA inhibition shortly after acidification. Similar operation performance was ultimately achieved for the TD and MD by the counteractions, with a methane yield and volatile solids (VS) removal efficiency at about 0.60 L/g VS added and 75.0%, respectively. In summary, combined pH control and trace metal supplementation, and prevention and recovery of LCFA inhibition were necessary for the stability insurance of a long-term continuous digestion of oily food waste. [Display omitted] • Long and stable continuous digestion of high-solid oily food waste was explored. • Fatty acid inhibition remained inevitable, besides lacking alkalinity and nutrient. • Maintaining pH above 6.80 and nutrient addition needed to be performed in couple. • 55 °C required more nutrient at 0.10 mg Fe, 0.01 mg Co and Ni per gram of COD added. • The coping strategies were proven effective in achieving 0.60 L methane/g VS added. [ABSTRACT FROM AUTHOR]

The hydrodynamic disintegration process depends, among others, on operational parameters like rotational speed or introduced energy. The study presents an interdisciplinary approach to the hydrodynamic disintegration parameters impact assessment on the internal processes and disintegration effects on the example of sewage sludge treatment. Three rotational speeds were considered, including fluid properties change at selected disintegration stages. Disintegration effects were measured in the bench tests. Soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFA) were measured before and after disintegration process. The assessment of the effects of disintegration employed the disintegration degree and the assessment of the course of methane production employed biochemical methane potential (BMP) tests. Fluid properties change during the disintegration stages does not cause a significant change in the flow structure. Due to the mathematical modelling results, at 1500 rpm no cavitation phenomenon was observed. Although, the bench tests results indicates, for the rotational speed 1500 rpm, organic compounds released to the liquid were characterised by higher susceptibility to biological decomposition than those released for 2500 and 3000 rpm (as suggested by the low SCOD/VFA values for 1500 rpm). Obtained results have confirmed, that the main phenomenon responsible for the disintegration effect is mechanical shredding not cavitation. [Display omitted] • Global policy and trends force green energy transformation in WWTPs. • The possibility of increasing the renewable energy production was investigated. • CFD analysis allowed to the internal flow structure, i.e. cavitation zones evaluation. • No cavitation for 1500 rpm, boundary speed - 2500 rpm, cavitation at 3000 rpm. • From 2.6 to 6.2% increase in methane production was observed for disintegrated sludge. [ABSTRACT FROM AUTHOR]

Escalating global water pollution exacerbated by textile-dyeing wastewater (TDW) poses significant environmental and health concerns due to the insufficient treatment methods being utilized. Thus, it is imperative to implement more effective treatment solutions to address such issues. In this research, different environmentally-friendly strategies involving effluent recirculation (ER) and Rubia cordifolia plant-derived purpurin electron mediator (EM) were introduced to enhance the treatment of real TDW and bioelectricity generation performance of an anti-gravity flow microbial fuel cell (AGF-MFC). The results revealed that optimum performance was achieved with a combination of hydraulic retention time (HRT) of 48 h with a recirculation ratio of 1, where the reduction efficiency of biochemical oxygen demand (BOD 5), chemical oxygen demand (COD), ammonium (NH 4 +), nitrate (NO 3 −), sulphate (SO 4 2−), ammonia nitrogen (NH 3 –N), colour and turbidity were 82.17 %, 82.15 %, 85.10 %, 80.52 %, 75.91 %, 59.52 %, 71.02 % and 93.10 %, respectively. In terms of bioelectricity generation performance, AGF-MFC showed a maximum output voltage and power density of 404.72 mV and 65.16 mW/m2, respectively. Moreover, the results also signified that higher treatment performance of TDW was obtained with natural purpurin from Rubia cordifolia plant than synthetic purpurin as EM. The reduced reactivity of highly stable synthetic purpurin EM for mediating the electron transfer was a contributing factor to the outperformance of plant-derived purpurin. Additionally, detailed electron-mediating mechanisms of purpurin were proposed to unravel the underlying electron transfer pathway involved in AGF-MFC. This research offers insight into the development of more sustainable solutions for managing TDW, and consequently reducing environmental pollution. [Display omitted] • Effective treatment of real textile-dyeing wastewater with energy recovery were achieved. • Positive effects of effluent recirculation on treatment performance were evidenced. • Sustainable use of purpurin electron mediator from medicinal plant was presented. • Electron-mediating mechanisms of purpurin were proposed. [ABSTRACT FROM AUTHOR]

The biodegradation of guar gum by microorganisms sourced from coalbeds can result in low-temperature gel breaking, thereby reducing reservoir damage. However, limited attention has been given to the influence of salinity on the synergistic biodegradation of coal and guar gum. In this study, biodegradation experiments of guar gum and lignite were conducted under varying salinity conditions. The primary objective was to investigate the controlling effects and mechanisms of salinity on the synergistic biodegradation of lignite and guar gum. The findings revealed that salinity had an inhibitory effect on the biomethane production from the co-degradation of lignite and guar gum. The biomethane production declined with increasing salinity levels, decreasing from 120.9 mL to 47.3 mL. Even under 20 g/L salt stress conditions, bacteria in coalbeds could effectively break the gel and the viscosity decreased to levels below 5 mPa s. As salinity increased, the removal rate of soluble chemical oxygen demand (SCOD) decreased from 55.63% to 31.17%, and volatile fatty acids (VFAs) accumulated in the digestion system. High salt environment reduces the intensity of each fluorescence peak. Alterations in salinity led to changes in microbial community structure and diversity. Under salt stress, there was an increased relative abundance of Proteiniphilum and Methanobacterium , ensuring the continuity of anaerobic digestion. Hydrogentrophic methanogens exhibited higher salt tolerance compared to acetoclastic methanogens. These findings provide experimental evidence supporting the use of guar gum fracturing fluid in coalbeds with varying salinity levels. [Display omitted] • Salinity had an inhibitory effect on the biomethane production of lignite and guar gum. • Even under 20 g/L salt stress conditions, bacteria could effectively break the gel. • As Salinity increased, the removal rate of SCOD decreased, and VFAs accumulated. • Proteiniphilum and Methanobacterium ensured the continuity of anaerobic digestion. [ABSTRACT FROM AUTHOR]

The limited availability of carbon sources in low carbon source wastewater has always hindered nitrogen removal efficiency. The residual slurry liquid after anaerobic digestion has the potential to be used as a carbon source. This study investigated the optimal parameters of dissolved oxygen (DO) for enhancing the treatment of low carbon source wastewater using slurry, and revealed the characteristics of carbon metabolism gene enrichment and carbon fixation potential driven by DO. The results indicated that treating wastewater under high DO concentrations (3–4 mg/L) conditions could meet the emission standards set by wastewater treatment plants in China. However, the lower-cost DO concentration of 3 mg/L is considered a more cost-effective parameter, effectively removing 85.68% of chemical oxygen demand and 91.56% of total nitrogen. Mechanistic analysis suggested that reducing DO concentration increased the diversity of microbial communities. Regulating DO concentration reshaped the co-metabolic network of microorganisms with different DO sensitivities by influencing Hydrogenophaga and Chlorobium. This ultimately led to the reconstruction of heterotrophic microbial communities dominated by Sphaerotilus and Acidovorax under high DO conditions, and heterotrophic-autotrophic co-enriched microbial communities dominated by Chlorobium under low DO conditions (1–2 mg/L). Additionally, under high DO conditions, high microbial mass transfer efficiency and the enrichment of functional genes were crucial for achieving high nitrogen removal performance. Further, the microbial carbon fixation potential was relatively high under the DO 3 mg/L condition, helping to reduce the consumption of additional carbon sources. This study provided innovative ideas for the sustainable and low-carbon development of wastewater treatment technology. [Display omitted] • DO concentration of 3 mg/L is the most cost-effective parameter for nitrogen removal. • Microbial communities dominated by Sphaerotilus and Acidovorax shift to Chlorobium. • DO drives the microbial network by affecting Hydrogenophaga and Chlorobium. • High DO conditions promote mass transfer and nitrogen removal genes enrichment. • Microbial carbon fixation potential is better at a DO concentration of 3 mg/L. [ABSTRACT FROM AUTHOR]

Signal transduction is an important mode of algae-bacteria interaction, in which bacterial quorum sensing (QS) may affect microalgal growth and metabolism. Currently, little is known whether acyl homoserine lactones (AHLs) released by bacteria can affect the pollutant removal by algae-bacteria consortia (ABC). In this study, we constructed ABC using Chlorella vulgaris (Cv) with two AHLs-producing bacteria and investigated their performance in the removal of multiple pollutants, including chemical oxygen demand (COD), total nitrogen (TN), phosphorus (P), and cadmium (Cd). The AHLs-producing bacteria, namely Agrobacterium sp. (Ap) and Ensifer adherens (Ea), were capable of forming a symbiosis with C. vulgaris. Consortia of Cv and Ap with ratio of 2:1 (Cv2-Ap1) showed the optimal growth promotion and higher removal of Cd, COD, TN, and P compared to the C. vulgaris monoculture. Cv2-Ap1 ABC removed 36.1–47.5% of Cd, 94.5%–94.6% COD, 37.1%–56.0% TN, and 90.4%–93.5% P from the culture medium. In addition, increase of intracellular neutral lipids and extracellular protein, as well as the types of functional groups on cell surface contributed to Cd removal and tolerance in the Cv2-Ap1 ABC. Six AHLs were detected in the Cv2-Ap1 culture. Among these, 3OC8-HSL and 3OC12-HSL additions promoted the ABC growth and enhanced their Cd accumulation. These findings may contribute to further understanding of AHL-mediated communication between algae and bacteria and provide support bioremediation efforts of metal-containing wastewater. [Display omitted] • Agrobacterium sp. (Ap) enhanced the growth of C. vulgaris (Cv). • Optimal COD, TN, TP and Cd removal achieved in the Cv2-Ap1 consortia. • More EPS, neutral lipids and functional groups detected in Cv2-Ap1. • 3OC8-HSL and 3OC12-HSL increased the Cd accumulation by Cv2-Ap1. [ABSTRACT FROM AUTHOR]

An investigation was conducted on the electrocoagulation treatment of high-strength young landfill leachate using an electrode made of aluminium in a batch electrochemical cell reactor. An iron sheet of 1 m⨯1 m⨯1.1 m (L: B: H) was used to construct the two landfill simulating reactors, both the reactors were operated at different conditions, i.e., one without rainfall (S 1) and the other with rainfall (S 2). Both reactors have 51% wet and 49% dry waste, which is the typical waste composition of India, and the quantity of waste taken was 450 kg; hence, the generated leachate was treated. This work focuses on the utilization of electrocoagulation as the sole treatment method where coagulation and adsorption occur simultaneously for young landfill leachate. The study employed a central composite design (CCD) to systematically vary the initial pH, current density (CD), and reaction time to examine their impact on the removal efficiency of COD (Chemical oxygen demand), TOC (Total organic carbon), and TSS (Total Suspended Solids). The optimum conditions obtained were a pH of 7.35, a CD of 15.29 mA/cm2, and a reaction duration of 57 min. When the conditions were optimized, the COD, TSS, and TOC removal efficiencies were 83.56%, 73.12%, and 85.58%, respectively. Also, the electrodes depleted 2.78 g of Al/L. In addition, pseudo-first-order and pseudo-second-order kinetics were employed to examine the elimination of contaminants by adsorption on aluminium hydroxide, thereby confirming the adsorption process. After investigation through energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD), with the produced sludge confirmed that electrocoagulation removed a significant amount of metals from landfill leachate. [Display omitted] • Characterization of leachate produced from 51% wet waste and 49% dry waste. • Electrocoagulation is found as an effective for treating very high strength young leachate. • Response surface methodology was used to optimize the treatment process for maximum COD, TOC and TSS removal. • Electrocoagulation is highly efficient in removing metals. [ABSTRACT FROM AUTHOR]

To achieve efficient and cost-effective treatment for the rural wastewater, a novel humus biochemical system (HBS) process derived from humus bio-functional material was proposed to treat rural wastewater under low dissolved oxygen (DO) conditions, and the operational performance, sludge characteristics, and microbial community in HBS were systematically investigated in this study. The results indicated that the HBS reactor could be operated stably under low DO levels of 0.2–0.8 mg/L, and maintained high removal efficiencies of 96.4%, 96.0%, and 88.2% for chemical oxygen demand, ammonia nitrogen, and total nitrogen, with corresponding effluent concentrations of 11.0, 1.7, and 5.1 mg/L, respectively. The sludge produced from HBS was characterized by relatively large particle size, complex structural morphology, and abundant humic substances, which favorably improved the system stability. Illumina sequencing demonstrated that HBS reactor possessed high microbial abundance and diversity and was enriched with plenty of nitrifying and denitrifying bacteria, which synergistically intensified the whole biological nitrogen removal process in this system. The study presented the feasibility and adaptability of HBS for energy-efficient rural wastewater treatment. [Display omitted] • Novel HBS process with low energy consumption was proposed to treat rural wastewater. • HBS sludge was characterized by large particle size and complex structural morphology. • Distinctive microbial community with high abundance and diversity were cultured in HBS. • HBS bioreactor achieved efficient removal for N and COD under low DO conditions. [ABSTRACT FROM AUTHOR]

Productive activities such as pig farming are a fundamental part of the economy in Mexico. Unfortunately, because of this activity, large quantities of wastewater are generated that have a negative impact in the environment. This work shows an alternative for treating piggery wastewater based on advanced oxidation processes (Fenton and solar photo Fenton, SPF) that have been probed successfully in previous works. In the first stage, Fenton and SPF were carried out on a laboratory scale using a Taguchi L9-type experimental design. From the statistical analysis of this design, the operating parameters: pH, time, hydrogen peroxide concentration [H 2 O 2 ], and iron ferrous concentration [Fe2+] that maximize the response variables: Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), and color were chosen. From these, a cascade forward neural network was implemented to establish a correlation between data from the variables to the physicochemical parameters to be measure being that a great fit of the data was obtained having a correlation coefficient of 0.99 which permits to optimize the pollutant degradation and predict the removal efficiencies at pilot scale but with a projection to a future industrial scale. A relevant result, it was found that the optimal values for maximizing the removal of physicochemical parameters were pH = 3, time = 60 min, H 2 O 2 /COD = 1.5 mg L−1, and H 2 O 2 /Fe2+ = 2.5 mg L−1. With these conditions degradation percentages of 91.44%, 47.14%, and 97.89% for COD, TOC, and color were obtained from the Fenton process, while for SPF the degradation percentage increased moderately. From the ANN analysis, the possibility to establish an intelligent system that permits to predict multiple results from operational conditions has been achieved. [Display omitted] • Piggery wastewater was treated successfully by Fenton and solar photo Fenton. • Optimization using Taguchi L9 design was improved with the use of machine learning. • Artificial Neural Networks provide a tool for decision-making in wastewater treatment. • Artificial Neural Networks can be applied to evaluate a pilot-scale treatment plant. [ABSTRACT FROM AUTHOR]

This work investigated the treatment of azo dye-containing wastewater in an upflow anaerobic sludge blanket (UASB) reactor combined with an electro-membrane bioreactor (EMBR). Current densities of 20 A m−2 and electric current exposure mode of 6′ON/30′OFF were applied to compare the performance of the EMBR to a conventional membrane bioreactor (MBR). The results showed that dye (Drimaren Red CL-7B) removal occurred predominantly in the UASB reactor, which accounted for 57% of the total dye removal achieved by the combined system. When the MBR was assisted by electrocoagulation, the overall azo dye removal efficiency increased from 60.5 to 67.1%. Electrocoagulation batch tests revealed that higher decolorization rates could be obtained with a current density of 50 A m−2. Over the entire experimental period, the combined UASB-EMBR system exhibited excellent performance in terms of chemical oxygen demand (COD) and NH 4 +-N removal, with average efficiencies above 97%, while PO 4 3--P was only consistently removed when the electrocoagulation was used. Likewise, a consistent reduction in the absorption spectrum of aromatic amines was observed when the MBR was electrochemically assisted. In addition to improving the pollutants removal, the use of electrocoagulation reduced the membrane fouling rate by 68% (0.25–0.08 kPa d−1), while requiring additional energy consumption and operational costs of 1.12 kWh m−3 and 0.32 USD m−3, respectively. Based on the results, it can be concluded that the combined UASB-EMBR system emerges as a promising technological approach for textile wastewater treatment. • A combined UASB-EMBR system was used to treat azo dye-containing wastewater. • COD, NH 4 +-N, PO 4 3--P, and azo dye were simultaneously removed at low CD (20 A m−2). • The use of electrocoagulation favored the removal of aromatic compounds. • The membrane fouling rate decreased by 68% when using the electrocoagulation. • Low energy demand (kWh m−3) was noticed compared to other electrocoagulation cells. [ABSTRACT FROM AUTHOR]

Oil refineries produce annually large quantities of oily sludge and non-biodegradable wastewater during petroleum refining that require adequate management to minimize its environmental impact. The fraction solid of the oily sludge accounts for 25 wt% and without treatment for their valorization. This work is focused on the valorization of these solid particles through their transformation into porous materials with enhanced properties and with potential application in the catalytic wet air oxidation (CWAO) of a non-biodegradable spent caustic refinery wastewater. Hence, dealing with the valorization and treatment of both refinery wastes in a circular approach aligned with the petrol refinery transformations by 2050. The obtained oily sludge carbonaceous materials showed improved surface area (260–762 m2/g) and a high Fe content. The good catalytic performance of these materials in CWAO processes has been attributed to the simultaneous presence of surface basic sites and iron species. Those materials with higher content of Fe and basic sites yielded the highest degradation of organic compounds present in the spent caustic refinery wastewater. In particular, the best-performing material ACT-NP 1.1 (non-preoxidated and thermically treated with 1:1 mass ratio KOH:solid) showed a chemical oxygen demand (COD) removal of 60 % after 3 h of reaction and with a higher degradation rate than that achieved with thermal oxidation without catalyst (WAO) and that using an iron-free commercial activated carbon. Moreover, the biodegradability of the treated wastewater increased up to 80% (from ca. 31% initially of the untreated effluent). Finally, this material was reused up to three catalytic cycles without losing metal species and keeping the catalytic performance. [Display omitted] • Oily sludge solid particles can be valorizated into new carbonaceous materials. • Oily sludge-based materials reached up to 60% of COD removal in CWAO processes. • Spent caustic refinery wastewater treated by CWAO reached 84% of biodegradability. • This study proposes a circular approach for the treatment of two petrol refinery wastes. [ABSTRACT FROM AUTHOR]

Source separation and decentralized domestic wastewater treatment represent effective strategies to enhance sewage treatment performance and facilitate water reuse economically. The Living Machine (LM) system has gained widespread adoption for decentralized sewage treatment. While underwater light source has been demonstrated to enhance the treatment performance of open aerobic reactors in LM systems, its influence on the treatment efficiency of a fully multistage LM system remains underreported. In this study, an underwater lamp-added LM system (ULLM) with eight reactors was constructed and investigated. The introduction of underwater light source obviously improved the removal capacity of chemical oxygen demand (COD) and NH 4 +-N, which was 96.1% and 61.6%, respectively. The diversity of algae, zooplankton, and aquatic animals was notably higher in the light-treated reactors than in the control group (CK) without underwater light source, and substantial alteration in the microbial community of the light-treated reactors was observed compared with CK reactors. At the phylum level, Proteobacteria and Nitrospirae enriched in the underwater light-treated reactors, while Bacteroidetes and Actinobacteria exhibited a decrease after light exposure. At the genus level, Nitrospira and Rhodanobacter were enriched in the ULLM system. Importantly, the prevalence of these two dominant genera was sustained until the final operational stage, indicating their potential key roles in enhancing wastewater treatment performance. The addition of underwater light source proves to be an effective strategy for augmenting the treatment efficiency of the multistage living machine systems, resulting in substantial improvements in pollutant removal. These findings contribute valuable insights into optimizing LM systems for decentralized wastewater treatment. • Underwater lamps were applied in a multistage living machine. • The removal rate of NH 4 +-N increased significantly. • TP removal performance was far more stable. • Bacterial and algal species composition were significantly changed after light exposure. • Prevalence of Nitrospira and Rhodanobacter sustained until the end stage in light treated system. [ABSTRACT FROM AUTHOR]

Low methane production and long retention time are the main dilemmas in current anaerobic digestion (AD) of waste activated sludge (WAS). This work used WAS as only substrate to prepare oriented multi-enzyme (ME) that directly used for WAS pretreatment. Under the optimal parameters, the highest activities of protease and amylase in ME could respectively reach 16.5 U/g and 580 U/g, and the corresponding methane production attained 197 mLCH 4 /g VS, which was increased by 70.4% compared to blank group. It was found that ME pretreatment could strengthen WAS disintegration and organic matters dissolution, lead to the soluble chemical oxygen demand (SCOD) was increased from the initial 486 mg/L to 2583 mg/L, and the corresponding volatile suspended solid (VSS) and extracellular polymeric substances (EPS) were reduced by 27% and 73.8%, respectively. The results of three-dimensional excitation-emission matrix (3D-EEM) and Fourier transform infrared spectroscopy (FTIR) indicated that protein disintegration may be the critical step during the process of WAS hydrolysis with ME, of which the release of tyrosine-like proteins achieved the better biodegradability of WAS, while the results of X-ray photoelectron spectroscopy (XPS) showed that the formation of protein derivatives was the main harmful factor that could extend the lag phase of AD process. Microbial communities analysis further suggested that ME pretreatment facilitated the enrichment of acetogenic bacteria and acetotrophic methanogens, which caused the transition of the methanogenesis pathway from hydrogenotrophic to acetotrophic. This study is expected to furnish valuable insight for ME pretreatment on enhancing WAS disintegration and methane production. [Display omitted] • An oriented multi-enzyme (ME) was developed from waste activated sludge (WAS). • ME pretreatment greatly facilitated WAS disintegration and nutrients dissolution. • The methane production was increased by 70.4% after 8 h ME pretreatment. • Disintegration of protein is the critical driving force during enzymatic hydrolysis. • Functional bacteria and archaea were significantly enriched after ME pretreatment. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the effect of hydrothermal pretreatment on the solubilization and anaerobic digestion (AD) of Scenedesmus sp. biomass. At first, the microalgae was cultivated in 5% fresh leachate (FL) to recover nutrients such as nitrogen and phosphorus. Scenedesmus sp. grown in 5% FL obtained 100%, 77% and 97% removal efficiency of ammonium nitrogen (NH 4 + - N), total Kjeldahl nitrogen (TKN) and phosphate phosphorous (PO 4 3− -P), respectively. In the following step, the hydrothermal pretreatment of Scenedesmus sp. biomass was carried out at 120, 150 and 170 °C and retention time of 0, 30 and 60 min to evaluate its solubilization and biogas production through AD in batch test. Soluble chemical oxygen demand (sCOD) increased by 260% compared to untreated microalgae at 170 °C for 60 min. In comparison to untreated microalgae, the highest increase in biogas (70%) and methane yield (100%) was observed for 150 °C and 60 min pretreated microalgae as a consequence of hydrothermal pretreatment. Hydrothermal pretreatment has shown effectiveness in enhancing biomass solubilization and increasing biogas yield. Nevertheless, further research at the pilot scale is necessary to thoroughly evaluate the potential and feasibility of hydrothermal pretreatment for full-scale implementation. [Display omitted] • Microalgae growth in fresh leachate and the biomass use for biogas production. • Hydrothermal pretreatment of Scenedesmus sp. was done. • Pretreatment increased soluble chemical oxygen demand by 260%. • Hydrothermal temperature has stronger solubilization and degradation effect than the reaction time. • Pre-treatment increased methane yield by 100%. [ABSTRACT FROM AUTHOR]

The abuse and uncontrolled discharge of antibiotics present a severe threat to environment and human health, necessitating the development of efficient and sustainable treatment technology. In this work, we employ a facile one-step electrodeposition method to prepare polyaniline/graphite oxide (PANI/GO) and samarium (Sm) co-modified Ti/PbO 2 (Ti/PbO 2 -PANI/GO-Sm) electrode for the degradation of amoxicillin (AMX). Compared with traditional Ti/PbO 2 electrode, Ti/PbO 2 -PANI/GO-Sm electrode exhibits more excellent oxygen evolution potential (2.63 V) and longer service life (56 h). In degradation experiment, under optimized conditions (50 mg L−1 AMX, 20 mA cm−2, pH 3, 0.050 M Na 2 SO 4 , 25 °C), Ti/PbO 2 -PANI/GO-Sm electrode achieves remarkable removal efficiencies of 88.76% for AMX and 79.92% for chemical oxygen demand at 90 min. In addition, trapping experiment confirms that ·OH plays a major role in the degradation process. Based on theoretical calculation and liquid chromatography-mass spectrometer results, the heterocyclic portion of AMX molecule is more susceptible to ·OH attacks. Thus, this novel electrode offers a sustainable and efficient solution to address environmental challenges posed by antibiotic-contaminated wastewater. The degradation mechanism and electrode performance are depicted. [Display omitted] • A unique Ti/PbO 2 -PANI/GO-Sm electrode has been successfully prepared. • Ti/PbO 2 -PANI/GO-Sm electrode exhibits excellent electrochemical oxidation performance. • Degradation mechanism and pathway are studied through DFT calculation and LC-MS. [ABSTRACT FROM AUTHOR]

The accelerating environmental impact of the textile industry, especially in water management, requires efficient wastewater treatment strategies. This study examines the effectiveness of various electrode pairs in the Electrocoagulation (EC) process for treating textile wastewater, focusing on removing of Total Suspended Solids (TSS), turbidity, Chemical Oxygen Demand (COD), and Total Organic Carbon (TOC). A comprehensive analysis was conducted using thirty-six electrode pair combinations, consisting of six materials: Aluminium (Al), Zinc (Zn), Carbon (C), Copper (Cu), Mild Steel (MS), and Stainless Steel (SS). The results demonstrated that different electrode pairs yielded varying removal efficiencies for various pollutants, with the highest efficiencies being 92.09% for COD (Al–C pair), 99.66% for TSS (Al–Cu pair), 99.17% for turbidity (Al-MS pair), and 70.99% for TOC (SS-SS pair). However, no single electrode pair excelled in removing all pollutant categories. To address this, three Multi-Criteria Decision Making (MCDM) methods such as TOPSIS, VIKOR, and PROMETHEE II were used to assess the most effective electrode pair. The results indicated that the Al–Zn combination was the most efficient, exhibiting high removal efficiencies for various pollutants (99.32% for TSS, 98.88% for turbidity, 68.62% for COD, and 57.96% for TOC). This study demonstrates that the EC process can effectively treat textile effluent and emphasizes the importance of selecting suitable electrode materials. Furthermore, pollutant removal was optimal with the Al–Zn electrode pair, offering a balanced and efficient approach to textile wastewater treatment. Thus, MCDM methods offer a robust framework for assessing and optimizing electrode selection, providing valuable insights for sustainable environmental management practices. • Electrocoagulation (EC) was implemented to remove impurities from textile effluent. • Evaluated 36 electrode pairs for textile wastewater treatment in EC process. • MCDM methods such as TOPSIS, VIKOR, and PROMETHEE II were utilized. • COD, TSS, turbidity, and TOC removal were 92.09, 99.66, 99.17, and 70.99%. • Al–Zn pair seen as most the efficient in removal of COD, TSS, turbidity and TOC. [ABSTRACT FROM AUTHOR]

This study provides a comprehensive analysis of the potential impact of hydrothermal pretreatment (HTP) on municipal thickened waste-activated sludge (TWAS) and its integration with anaerobic digestion (AD). The research demonstrates that HTP conditions (170 °C, 3 bars for 30 min) can increase the solubilization of macromolecular organic compounds by 41%, which enhances biodegradability in semicontinuous bioreactors. This treatment also results in a 50% reduction in chemical oxygen demand (COD) and a 63% increase in the destruction of volatile solids (VS). The combination of HTP with AD significantly boosts methane yields by 51%, reaching 176 ml/g COD, and improves the digestate dewaterability, doubling the solid content in the dewatered cake. However, a higher polymer dose is required compared to conventional AD. Microbial community analysis correlates the observed performance and alterations; it indicates that HTP enhances resilience to stress conditions such as ammonia toxicity. This comprehensive study provides valuable insights into the transition from wastewater treatment plants (WWTPs) to resource recovery facilities (RRF) in line with circular economy principles. • HTP before AD boosts solubilization of complex organics by 41%. • HTP followed by AD achieves a 50% reduction in COD and a 63% reduction in volatile solids. • HTP coupled with AD doubles dewaterability, requiring a 13.6% higher polymer dose. • Impacts of viscosity and particle size distribution on dewaterability performance were investigated. • HTP induces significant alterations in the microbial community. [ABSTRACT FROM AUTHOR]

Tetrabromobisphenol A (TBBPA) and microplastics are emerging contaminants of widespread concern. However, little is known about the effects of combined exposure to TBBPA and microplastics on the physicochemical properties and microbial metabolism of anaerobic granular sludge. This study investigated the effects of TBBPA, polystyrene microplastics (PS MP) and polybutylene succinate microplastics (PBS MP) on the physicochemical properties, microbial communities and microbial metabolic levels of anaerobic granular sludge. The results showed that chemical oxygen demand (COD) removal of sludge was lowest in the presence of TBBPA alone and PS MP alone with 33.21% and 30.06%, respectively. The microorganisms promoted the secretion of humic substances under the influence of TBBPA, PS MP and PBS MP. The lowest proportion of genes controlling glycolytic metabolism in sludge was 1.52% when both TBBPA and PS MP were added. Microbial reactive oxygen species were increased in anaerobic granular sludge exposed to MP S. In addition, TBBPA treatment decreased electron transfer of the anaerobic granular sludge and disrupted the pathway of anaerobic microorganisms in acquiring adenosine triphosphate, and MPs attenuated the negative effects of TBBPA on the acetate methanogenesis process of the anaerobic granular sludge. This study provides a reference for evaluating the impact of multiple pollutants on anaerobic granular sludge. [Display omitted] • COD removal rate of anaerobic granular sludge was the lowest in TBBPA group. • Genes controlling glycolytic metabolism in sludge was lowest in TBBPA and PS MP group. • Presence of TBBPA and MPs affected the genes involved in ATP. • ROS in anaerobic granular sludge exposed to MP S was increased. [ABSTRACT FROM AUTHOR]

This study has carried out a systematic review of 36 scientific papers (reporting 63 case studies) published in the last 15 years about the treatment of industrial, agri-food and municipal wastewater in lagoons. A concentration of studies from a few countries (Italy, Algeria and Iran) and about municipal wastewater (70% of papers) was revealed by the bibliographic analysis. Aeration was supplied in more than 50% of case studies; the storage capacity of lagoons (adopted as a measure of size) was extremely variable (over seven orders of magnitude), while their depth was generally lower than a few metres. The efficiency of lagoon treatments at removing COD was in a wide range (25–98%). Very few studies analysed the energy intensity of treatments in lagoons. The meta-analysis applied to a further selection of 10 papers with 29 case studies revealed significant differences in pH and dissolved oxygen concentration, due to aeration or type of treated wastewater. Treatment efficiency was higher in aerated lagoons compared to non-aerated systems, and did not depend on the type of treated wastewater. Based on the analysis of the reviewed papers, an urgent research need on this topic arises, mainly due to the oldness of most analysed studies. Practical suggestions are given to optimise the depuration performances of lagoons: (i) application of intermittent and night aeration; (ii) reduced air flow rates; (iii) adaptation of microbial biomass to high contents of inhibiting compounds in wastewater; (iv) construction of baffles to keep the planned hydraulic retention time avoiding short-circuit; (v) integration of lagoons with other treatments (e.g., constructed wetlands); (vi) ferti-irrigation of crops with lagoon effluents rather than disposal into water bodies. • A systematic review of 36 scientific papers (reporting 63 case studies) is presented. • The efficiency of lagoons at removing organic compounds was in a wide range (25–98%). • Treatment efficiency was higher in aerated lagoons compared to non-aerated systems. • This efficiency did not depend on the type of treated wastewater. • Practical suggestions are given to optimise the depuration performances of lagoons. [ABSTRACT FROM AUTHOR]

The chemical oxygen demand (COD) in the Seto Inland Sea, Japan has increased in the recent decades due to the increase of bottom dissolved oxygen (DO) concentration which stimulated several autotrophic microorganisms, specially sulfur oxidizing bacteria (SOB). This increased SOB activity due to the oxygenation of the bottom sediment synthesized new organic matter (OM) which contributed dissolved organic carbon to the overlying seawater. This phenomenon further led to hypoxia in some subareas in the Seto Inland Sea. Higher pH or alkaline environment has been found to be an unfavorable condition for SOB. In this research, we used decarburization slag to elevate the pH of sediment to control the SOB activity and consequently reduce OM production in the sediment. Ignition loss of the surface sediment increased from 5.14% 6.38% after 21 days of incubation with aeration; whereas the sediment showed the less ignition loss of 5.71% after 21 days when the slag was incubated in the same experimental setup. Microbial community analysis showed less SOB activity in the slag added aerated sediment which accounts for the controlled increase of OM in the sediment. An additional experiment was conducted with magnesium oxide to confirm whether elevated pH can control the OM increase in sediment due to rising DO. All these results showed that decarburization slag can elevate the pH of the sediment to a certain level which can control the SOB activity followed by controlled increase of OM in the sediment. The findings may be beneficial to control accumulation of sedimentary OM which can act as a source of organic carbon in the overlying seawater. [Display omitted] • Organic matter increased in oxygenated sediment by sulfur oxidizing bacteria. • Decarburization slag suppressed increase in the sedimentary organic matter. • Proliferation of sulfur oxidizing bacteria was suppressed by the slag. • Alkaline elution was a cause for the suppressed increase in organic matter. [ABSTRACT FROM AUTHOR]

High-rate membrane bioreactors (MBR), where the wastewater undergoes partial oxidation due to the applied short sludge retention time (SRT) and hydraulic retention time (HRT) values, retain the majority of the organic substances in the sludge through growth and biological flocculation. Thus, a raw material source with a high biomethane production potential is created for the widespread use of circular economy or energy-neutral plants in wastewater treatment. While high-rate MBRs have been successfully employed for energy-efficient treatment of domestic wastewater, there is a lack of research specifically focused on textile wastewater. This study aimed to investigate the textile wastewater treatment and organic matter recovery performances of an aerobic MBR system containing a hollow fiber ultrafiltration membrane with a 0.04 μm pore diameter. The system was initially operated at short SRTs (5 and 3 d) and different SRT/HRT ratios (5, 10, and 20) and subsequently at high-rate conditions (SRT of 0.5–2 d and HRT of 1.2–9.6 h) which are believed to be the most limiting conditions tested for treatment of real textile wastewater. The results showed that chemical oxygen demand (COD) removal averaged 77% even at SRT of 0.5 d and HRT of 1.2 h. Slowly biodegradable substrates and soluble microbial products (SMP) accumulated within the MBR at SRT of 0.5 and 1 d, which resulted in decreased sludge filterability. The observed sludge yield (Y obs) exhibited a considerable increase when SRT was reduced from 5 to 1 d. On the other hand, the SRT/HRT ratio displayed a decisive effect on the energy requirement for aeration. [Display omitted] • COD removal in the MBR is high (77%) even at SRT of 0.5 d and HRT of 1.2 h. • Organic matter recovery significantly increases at SRTs ≤1 d. • Slowly biodegradable COD accumulates in the bulk at SRTs ≤1 d. • Membrane fouling increases significantly at SRTs ≤1 d. • Energy requirement decreased to 0.19 kWh/m3 or 0.3 kWh/kg-COD rem. at SRT 0.5 d. [ABSTRACT FROM AUTHOR]

The organic matter (OM) and nitrogen in Fresh leachate (FL) from waste compression sites pose environmental and health risks. Even though the constructed wetland (CW) can efficiently remove these pollutants, the molecular-level transformations of dissolved OM (DOM) in FL remain uncertain. This study reports the molecular dynamics of DOM and nitrogen removal during FL treatment in CWs. Two lab-scale vertical-flow CW systems were employed: one using only sand as substrates (act as a control, CW-C) and the other employing an equal mixture of manganese ore powder and sand (experimental, CW-M). Over 488 days of operation, CW-M exhibited significantly higher removal rates for chemical oxygen demand (COD), ammonia nitrogen (NH 4 +-N), and dissolved organic matter (represented by dissolved organic carbon, DOC) at 98.2 ± 2.5%, 99.2 ± 1.4%, and 97.9 ± 1.9%, respectively, in contrast to CW-C (92.8 ± 6.8%, 77.1 ± 28.1%, and 74.7 ± 9.5%). The three-dimensional fluorescence excitation-emission matrix (3D-EEM) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses unveiled that the influent DOM was predominantly composed of readily biodegradable protein-like substances with high carbon content and low unsaturation. Throughout treatment, it led to the degradation of low O/C and high H/C compounds, resulting in the formation of DOM with higher unsaturation and aromaticity, resembling humic-like substances. CW-M showcased a distinct DOM composition, characterized by lower carbon content yet higher unsaturation and aromaticity than CW-C. The study also identified the presence of Gammaproteobacteria , reported as Mn-oxidizing bacteria with significantly higher abundance in the upper and middle layers of CW-M, facilitating manganese cycling and improving DOM removal. Key pathways contributing to DOM removal encompassed adsorption, catalytic oxidation by manganese oxides, and microbial degradation. This study offers novel insights into DOM transformation and removal from FL during CW treatment, which will facilitate better design and enhanced performance. • DOM transformation during fresh leachate treatment using manganese-rich constructed wetlands (CW-M) was studied. • CW-M achieved extremely high COD, TN, and DOC removal efficiencies (>98%). • Protein-like substances and DOM with high carbon numbers and low unsaturation were efficiently removed. • DOM removal pathway comprises oxidation and adsorption by Mn oxide. [ABSTRACT FROM AUTHOR]

Hydrothermal liquefaction (HTL) is promising for treating waste with high moisture, such as municipal sludge, and producing biocrude (a petroleum-like biofuel). However, a large amount of wastewater byproduct, HTL aqueous, is generated. The presence of hazardous compounds (e.g., phenolic compounds and nitrogenous organics) makes HTL aqueous the biggest bottleneck for full-scale implementation at treatment plants. This study investigated the adsorption of various pollutants, focusing on chemical oxygen demand (COD), in HTL aqueous to granular activated carbon (GAC), biochar, and hydrochar. It assessed the effect of pH, temperature, time, and adsorbent concentration on adsorption efficiency and identified proper adsorbent and process conditions for removing most of the pollutants from HTL aqueous. GAC showed the highest adsorption capacity (184 mg/g) for COD, surpassing biochar (44 mg/g) and hydrochar (42 mg/g). The adsorption of COD to all adsorbents followed pseudo-second-order kinetic and Freundlich isotherm, suggesting that the adsorption of HTL aqueous pollutants is a heterogeneous and multilayer process, limited by chemosorption. The adsorption was endothermic, favored by elevated temperatures and neutral pH. This means adsorption is more efficient and economical for treating HTL aqueous that is a hot stream at the large-scale and it saves chemical needs. Lastly, GAC was highly efficient and selective in removing harmful pollutants, such as COD (up to 66%), total phenolic compounds (up to 94%), pyrazines (up to 99%), pyridines (up to 100%), and cyclic ketones (up to 95%) while preserving valuable volatile fatty acids (VFAs) and ammonia for subsequent recovery. Removal of potentially inhibitory compounds and preserving VFAs are crucial for carbon recovery in anaerobic biological treatment of HTL aqueous. The results suggested the necessity of optimizing adsorbent dose for maximizing removal of specific group of inhibitory compounds in full-strength HTL aqueous for enhancing downstream biological treatment. Lastly, this study established the groundwork for HTL aqueous adsorption, elucidating its effectiveness and mechanism for pollutant removal. [Display omitted] • The adsorption process fits pseudo-second-order kinetics and Freundlich isotherm. • The adsorption of HTL aqueous pollutants to all adsorbents was endothermic. • GAC was efficient in removing hazardous substances (phenols and N-heterocycles). • GAC can remove inhibitory compounds and keep volatile fatty acids for utilization. [ABSTRACT FROM AUTHOR]

Research on the potential for chemical energy recovery and the optimization of recovery pathways in different regions of China is still lacking. This study aimed to address this gap by evaluating the potential and optimize the utilization pathways for chemical energy recovery in various regions of China for achieving sustainable wastewater treatment. The results showed that the eastern and northeastern regions of China exhibited higher chemical energy levels under the existing operating conditions. Key factors affecting chemical energy recovery included chemical oxygen demand removal (ΔCOD), treatment scale, and specific energy consumption (μ) of wastewater treatment plants (WWTPs). Furthermore, the average improvement in the chemical energy recovery rate with an optimized utilization pathway was approximately 40% in the WWTPs. The use of the net-zero energy consumption (NZE) model proved effective in improving the chemical energy recovery potential, with an average reduction of greenhouse gas (GHG) emissions reaching next to 95% in the investigated WWTPs. [Display omitted] • Energy recovery in wastewater treatment plants (WWTPs) in China was investigated. • Eastern and northeastern regions of China exhibited higher chemical energy levels. • Chemical oxygen demand removal, scale and μ of WWTPs were key affecting factors. • Anaerobic-anoxic-oxic and anoxic-oxic process exhibited a higher energy recovery. • Large WWTPs generally have greater chemical energy recovery than small WWTPs. [ABSTRACT FROM AUTHOR]

The synergistic partial-denitrification, anammox, and fermentation (SPDAF) process presents a promising solution to treat domestic and nitrate wastewaters. However, its capability to handle fluctuating C/N ratios (the ratios of COD to total inorganic nitrogen) in practical applications remains uncertain. In this study, the SPDAF process was operated for 236 days with C/N ratios of 0.7–3.5, and a high and stable efficiency of nitrogen removal (84.9 ± 7.8%) was achieved. The denitrification and anammox contributions were 6.1 ± 7.1% and 93.9 ± 7.1%, respectively. Batch tests highlighted the pivotal role of in situ fermentation at low biodegradable chemical oxygen demand (BCOD)/NO 3 − ratios. As the BCOD/NO 3 − ratios increased from 0 to 6, the NH 4 + and NO 3 − removal rates increased, while the anammox contribution decreased from 100% to 80.1% but remained the primary pathway of nitrogen removal. The cooperation and balanced growth of denitrifying bacteria, anammox bacteria, and fermentation bacteria contributed to the system's robustness under fluctuating C/N ratios. [Display omitted] • The SPDAF process had a robustness under fluctuant C/N ratios of 0.7–3.5. • The SPDAF process obtained a stable and high nitrogen removal efficiency (84.9 ± 7.8%). • The anammox contribution (93.9 ± 7.1%) always kept at the lead in the nitrogen removal. • Fermentation played a key role in the full utilization of the complex organics. • Main functional bacteria cooperated and supported the robustness of SPDAF process. [ABSTRACT FROM AUTHOR]

The difficulty of the microbial conversion process for the degradation of sotol vinasse due to its high acidity and organic load makes it an effluent with high potential for environmental contamination, therefore its treatment is of special interest. Calcium carbonate is found in great abundance and has the ability to act as a neutralizing agent, maintaining the alkalinity of the fermentation medium as well as, through its dissociation, releasing CO 2 molecules that can be used by phototrophic CO 2 -fixing bacteria. This study evaluated the use of Rhodopseudomonas telluris (OR069658) for the degradation of vinasse in different concentrations of calcium carbonate (0, 2, 4, 6, 8 and 10% m/v). The results showed that calcium carbonate concentration influenced volatile fatty acids (VFA), alkalinity and pH, which in turn influenced changes in the degradation of chemical oxygen demand (COD), phenol and sulfate. Maximum COD and phenol degradation values of 83.16 ± 0.15% and 90.16 ± 0.30%, respectively, were obtained at a calcium carbonate concentration of 4%. At the same time, the lowest COD and phenol degradation values of 52.01 ± 0.38% and 68.21 ± 0.81%, respectively, were obtained at a calcium carbonate concentration of 0%. The data obtained also revealed to us that at high calcium carbonate concentrations of 6–10%, sotol vinasse can be biosynthesized by Rhodopseudomonas telluris (OR069658) to VFA, facilitating the degradation of sulfates. The findings of this study confirmed the potential for using Rhodopseudomonas telluris (OR069658) at a calcium carbonate concentration of 4% as an appropriate alternative treatment for sotol vinasse degradation. [Display omitted] • Carotenoid and Bacteriochlorophyll production by Rhodopseudomonas from sotol vinasse. • Rhodopseudomonas demonstrated its metabolic adaptability to grow in an opaque medium. • Rhodopseudomonas in presence of carbonate improved the degradation of sotol vinasse. [ABSTRACT FROM AUTHOR]

Biochar is a carbon-neutral tool for combating climate change. Artificial intelligence applications to estimate the biochar mitigation effect on greenhouse gases (GHGs) can assist scientists in making more informed solutions. However, there is also evidence indicating that biochar promotes, rather than reduces, N 2 O emissions. Thus, the effect of biochar on N 2 O remains uncertain in constructed wetlands (CWs), and there is not a characterization metric for this effect, which increases the difficulty and inaccuracy of biochar-driven alleviation effect projections. Here, we provide new insight by utilizing machine learning-based, tree-structured Parzen Estimator (TPE) optimization assisted by a meta-analysis to estimate the potency of biochar-driven N 2 O mitigation. We first synthesized datasets that contained 80 studies on global biochar-amended CWs. The mitigation effect size was then calculated and further introduced as a new metric. TPE optimization was then applied to automatically tune the hyperparameters of the built extreme gradient boosting (XGBoost) and random forest (RF), and the optimum TPE-XGBoost obtained adequately achieved a satisfactory prediction accuracy for N 2 O flux (R 2 = 91.90%, RPD = 3.57) and the effect size (R 2 = 92.61%, RPD = 3.59). Results indicated that a high influent chemical oxygen demand/total nitrogen (COD/TN) ratio and the COD removal efficiency interpreted by the Shapley value significantly enhanced the effect size contribution. COD/TN ratio made the most and the second greatest positive contributions among 22 input variables to N 2 O flux and to the effect size that were up to 18% and 14%, respectively. By combining with a structural equation model analysis, NH 4 +-N removal rate had significant negative direct effects on the N 2 O flux. This study implied that the application of granulated biochar derived from C-rich feedstocks would maximize the net climate benefit of N 2 O mitigation driven by biochar for future biochar-based CWs. [Display omitted] • TPE-optimized XGBoost is the state-of-the-art technology to predict N 2 O mitigation. • Effect size, a new metric of AutoML, characterized biochar-alleviating N 2 O efficacy. • A high influent COD/TN enhanced the biochar-driven N 2 O mitigation strength. • Granulated biochar derived from C-rich feedstocks would maximize N 2 O mitigation. [ABSTRACT FROM AUTHOR]

The present study investigates the treatment of real coke plant effluent utilising several ultrasound-based hybrid oxidation approaches including Ultrasound (US) alone, US + catalyst, US + H 2 O 2 , US + Fenton, US + Ozone, and US + Peroxone, with main objective as maximizing the reduction of chemical oxygen demand (COD). Ultrasonic horn at power of 130 W, frequency as 20 kHz and duty cycle as 70% was applied. Study with varying catalyst (TiO 2) dose from 0.5 g/L – 2 g/L revealed 1 g/L as the optimum dose resulting in 65.15% reduction in COD. A 40 ml/L dose of H 2 O 2 was shown to be optimal, giving an 81.96% reduction in COD, based on the study of varied doses of H 2 O 2 from 20 ml/L to 60 ml/L. US + Fenton reagent combination at optimum Fe2+/H 2 O 2 (w/v) ratio of 1:1 resulted in a COD reduction of 85.29% whereas reduction of COD as 81.75% was obtained at the optimum flow rate of ozone as 1 LPM for US + Ozone approach. US + Peroxone demonstrated the best efficiency (90.48%) for COD reduction. To find the toxicity effects, the treated (US + peroxone) and non-treated samples were tested for the growth of bacterial cultures. It was observed that the toxicity of the treated sample increased only marginally after treatment. High-resolution liquid chromatography mass spectrometry (HR-LCMS) analysis was also performed to establish intermediate compounds. Overall, the coupling of ultrasound with oxidation processes produced better results with US + Peroxone established as best treatment approach for coke plant effluent. [Display omitted] • Ultrasound based Advanced Oxidation Processes for coke oven plant effluent. • Ultrasound combined with H 2 O 2 , Fenton, Ozone, Peroxone, catalyst for COD reduction. • Ultrasound + Peroxone process resulted in 90.48% COD reduction. • Optimum parameters as 1 g/L catalyst, 40 ml/L H 2 O 2 , 1 LPM O 3 , Fe2+/H 2 O 2 (w/v) ratio of 1:1. • Toxicity analysis confirmed that few toxic intermediates are generated. [ABSTRACT FROM AUTHOR]

Deep learning methods exhibited significant advantages in mapping highly nonlinear relationships with acceptable computational speed, and have been widely used to predict water quality. However, various model selection and construction methods resulted in differences in prediction accuracy and performance. Hence, a unified deep learning framework for water quality prediction was established in the paper, including data processing module, feature enhancement module, and data prediction module. In the established model, the data processing module based on wavelet transform method was applied to decomposing complex nonlinear meteorology, hydrology, and water quality data into multiple frequency domain signals for extracting self characteristics of data cyclic and fluctuations. The feature enhancement module based on Informer Encoder was used to enhance feature encoding of time series data in different frequency domains to discover global time dependent features of variables. Finally, the data prediction module based on the stacked bidirectional long and short term memory network (SBiLSTM) method was employed to strengthen the local correlation of feature sequences and predict the water quality. The established model framework was applied in Lijiang River in Guilin, China. The maximum relative errors between the predicted and observed values for dissolved oxygen (DO), chemical oxygen demand (COD Mn) were 12.4% and 20.7%, suggesting a satisfactory prediction performance of the established model. The validation results showed that the established model was superior to all other models in terms of prediction accuracy with RMSE values 0.329, 0.121, MAE values 0.217, 0.057, SMAPE values 0.022, 0.063 for DO and COD Mn , respectively. Ablation tests confirmed the necessity and rationality of each module for the established model framework. The established method provided a unified deep learning framework for water quality prediction. [Display omitted] • A deep learning model coupling with data feature extraction and enhancement methods was developed • ESWT module was applied to extract the self characteristics of data • Enhancement module was adopted to enhance the global and local feature of data • The established model improves the accuracy of water quality prediction [ABSTRACT FROM AUTHOR]