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This study investigated the effects of microalgae growth on antibiotic removal and the attenuation of antibiotic resistance genes (ARGs)/ARGs host bacteria in algal-bacterial granular sludge (ABGS) system. In the presence of tetracycline (TC) and sulfadiazine (SDZ) mixture (2-4 mg/L), microalgae could grow on bacterial granular sludge (BGS) to form ABGS, with a chlorophyll-a content of 7.68-8.13 mg/g-VSS being achieved. The removal efficiencies of TC and SDZ by ABGS were as high as 79.0 % and 94.0 %, which were 4.3-5.0 % higher than those by BGS. Metagenomic analysis indicated that the relative abundances of TC/SDZ- related ARGs and mobile genetic elements (MGEs) in BGS were 56.1 % and 22.1 % higher than those in ABGS. A total of 26 ARGs were detected from the granules, and they were identified to associate with 46 host bacteria. 13 out of 26 ARGs and 13 out of 46 hosts were shared ARGs and hosts, respectively. The total relative abundance of host bacteria in BGS was 30.8 % higher than that in ABGS. Scenedesmus and Chlorella were the dominant microalgae that may reduce the diversity of ARGs hosts. Overall, ABGS is a promising biotechnology for antibiotic-containing wastewater treatment.

Alkaline-thermal pretreatment was examined for waste activated sludge (WAS) disintegration and subsequent anaerobic digestion (AD). Pretreatment at 60 °C was estimated to provide better economic benefits than higher temperature conditions. The maximum methane yield of 215.6 mL/g COD was achieved when WAS was pretreated at 60 °C and pH 10 for 24 h, which was 46.6% higher than untreated WAS. The pretreatment condition also provided the maximum net savings. The degree of sludge disintegration, considering both loosely bound-extracellular polymeric substance and soluble COD, would be a better indicator to predict anaerobic digestibility than the solubilization rate that considers soluble COD alone. Microbial analysis implied that pretreatment facilitated the growth of hydrolytic bacteria, phyla Bacteroidetes and Firmicutes. In addition, sludge pretreatment enhanced the growth of both acetoclastic and hydrogenotrophic methanogens, genera Methanosaeta and Methanobacterium. The mild AT-PT would be useful to enhance the digestion performance and economic benefit of WAS digestion.

In order to sustainably manage wastewater treatment plants and the environment, enhanced biological phosphorus (P) removal (EBPR) was proposed to achieve P recovery through extracting P-rich liquid (i.e., Phostrip) from the bottom of aerobic granular sludge (AGS)-based sequencing batch reactors (SBRs) under no mixing during the anaerobic phase. Results showed both tested bacterial AGS (BAGS) and algal-bacterial AGS (A-BAGS) systems stably produced low effluent P ( 99%). The collected P-rich liquids (55-83 mg-P/L) from both systems showed great potential for P recovery of about 83.85 ± 0.57 % (BAGS) or 83.99 ± 0.77% (A-BAGS), which were contributed by the influent P (> 95%) and P reserves in granules based on P balance analysis. This study suggests that the AGS-based SBRs coupling the Phostrip holds great potentials for P recovery profit and further reduction in energy consumption.

Air-nanobubble water (NBW) was applied to pre-acclimate anaerobically digested sludge that was then used as the inoculum in the two-stage anaerobic digestion (AD) of high saline (20 g NaCl/L) food waste (FW) to optimize NBW application in the AD of high saline FW. K+ was simultaneously supplemented during the methanogenic stage to resist the inhibition of salt on methanogens. Results showed that after the second pre-acclimation cycle, the inoculum activity was increased 27% in the Air-NBW supplemented reactor in comparison to the deionized water (DW) supplemented one. In the first-stage AD, H2 yield was enhanced by 46% in the Air-NBW pre-acclimated sludge reactor compared with the DW pre-acclimated sludge reactor. Besides, supplementation of K+ in the methanogenic stage could enhance methane production by 17-25% in the DW reactors at initial pH 7.5, 8.0, and 9.0 when compared to the control reactor (using NaOH adjusted initial pH to 7.5), respectively.

A synergistic process was proposed to prepare hydrochar by hydrothermal co-carbonization (HTcoC) of waste distillers grains with sewage sludge, focusing on hydrochar properties and combustion behavior under different mixing ratios. Results show that the co-hydrochar from HTcoC exhibited excellent synergistic characteristics with relatively high synergistic coefficients (0.1-1.2% for hydrochar yield, 4.8-8.0% for higher heating value (HHV), 8.0-12.6% for organic retention, and 2.2-4.0% for carbon retention, respectively), partially evidenced by FTIR data. And the co-hydrochar showed a higher fuel ratio of 0.09-0.13 with the fixed carbon increased to 8.3-10.0 at an remarkably enhanced coalification degree. Moreover, thermal analysis showed that the co-hydrochar exhibited improved combustion efficiency and a more stable flame. As a result, the HTcoC process with 13.0-22.5% increase in biofuel recovery rate and 25.6-47.7% increase in net energy gain may provide an effective approach for the conversion of both biomass wastes into clean biofuel.

Toxic cyanobacterial blooms frequently develop in eutrophic freshwater bodies worldwide. Microcystis species produce microcystins (MCs) as a cyanotoxin. Certain bacteria that harbor the mlr gene cluster, especially mlrA, are capable of degrading MCs. However, MC-degrading bacteria may possess or lack mlr genes (mlr+ and mlr− genotypes, respectively). In this study, we investigated the genotype that predominantly contributes to biodegradation and cyanobacterial predator community structure with change in total MC concentration in an aquatic environment. The 2 genotypes coexisted but mlr+ predominated, as indicated by the negative correlation between mlrA gene copy abundance and total MC concentration. At the highest MC concentrations, predation pressure by Phyllopoda, Copepoda, and Monogononta (rotifers) was reduced; thus, MCs may be toxic to cyanobacterial predators. The results suggest that cooperation between MC-degrading bacteria and predators may reduce Microcystis abundance and MC concentration.

Liquid nitrogen was employed as a low-temperature medium to activate zero-valent iron (ZVI) powder in an attempt to strengthen its enhancement effect on anaerobic digestion (AD) of swine manure (SM). Surprisingly, it was found that both pristine ZVI and liquid nitrogen-pretreated ZVI (LZVI) did not significantly improve the AD performance or change the archaeal community structure. It was hypothesized that ZVI might not be effective at stress-free environment like in these digesters. To confirm this, an additional set of AD experiments were performed at high ammonia stress (about 4000 mg/L), results showed that ZVI and LZVI greatly alleviated ammonia inhibition and increased the CH

This study presents a rapid method on how to speed up aerobic granular sludge (AGS) cultivation and ensure excellent and stable removal performance during bioreactor operation for domestic wastewater treatment. This new strategy consists of start-up the bioreactor using only anaerobic granular sludge (AnGS) as a seed and feeding with crude sewage extracted from a full-scale Extended Aeration Plant. This experiment used a 2.5 L lab-scale sequencing batch reactor (SBR). The bioreactor operated at low dissolved oxygen (DO) concentration controlled at the value of 2.0 mg/L and below. After 60 days of operation, it clearly showed that almost 90% of AnGS seeds turned from black color to brown. The physical characterization analysis showed that the average sizes were unchanged, and the granules remained compact. Also, the SBR operation monitored with brown granules showed stable removal performance. Average removal efficiencies during steady-state cycles at room temperature of COD, ammoniacal nitrogen, and phosphate reached 84%, 92%, and 100%, respectively.

Feammox process is crucial for the global nitrogen cycle and has great potentials for the treatment of low COD/NH

This study investigated the possibility of biogas recirculation-driven anaerobic granular sludge system for sewage sludge treatment, aiming to develop an energy sufficient and multifunctional anaerobic digestion (AD) system for sewage sludge with biogas upgrading, sludge stabilization and self-aggregation. Results show that biogas recirculation could enhance the CH4 production rate by 31–44% and shorten the lag-phase duration to 0.08–0.2 day with simultaneous increment of CH4 content (> 83% in this study). The reason is mainly associated with the stronger interspecies electron transfer under the biogas recirculation condition. In addition, 37–40% better dewaterability of the digested sludge was achieved, implying the occurrence of self-aggregation of microbial cells induced by biogas recirculation. Energy balance analysis reflects that this sewage sludge treatment system could enhance the net energy recovery by 78–85%. Moreover, almost no obvious influence was noticed on the seed granules’ composition and properties. These findings suggest that the biogas recirculation-driven anaerobic granular sludge system could be a promising alternative for sewage sludge treatment, which can improve biogas quality and sludge dewaterability simultaneously towards sludge self-aggregation with no addition of other chemicals.

Cobalt Hexacyanoferrate (CoHCF) was tested for the selective uptake of K from seawater and the electrochemical method was adopted for the desorption and regeneration of the material. Powder form CoHCF could adsorb about 6.5 mmol/g of K from the seawater. For the ease of the electrochemical desorption and regeneration, CoHCF thin film was coated onto the Indium Tin Oxide (ITO) glass to obtain a CoHCF electrode. K adsorption kinetics on CoHCF thin film was found to be well fitted with the intraparticle diffusion model, which was a two-step process. Five consecutive adsorption-desorption-regeneration cycles were carried out to know the gradual decrease in the adsorption capacity owing to changes in the redox states of two metals, Co and Fe, in the material. Fourier Transform Infrared Spectroscopy (FT-IR) and Ultraviolet-Visible (UV-Vis) measurement results corresponded to the color change of CoHCF thin film, indicating the valence change of transition metals and the exchange of alkali metal cations happened on the CoHCF at different operation stages. In order to elucidate the reaction mechanism, composition of the material was analysis in the following steps: adsorption, desorption, and regeneration. It was proved that the system based on CoHCF thin film modified electrode had the potential of recovering potassium from seawater.

In this study, CuO-CeO2 was synthesized via an easy hydrothermal-calcination method and innovatively applied to peroxymonosulfate (PMS) activation for pollutants degradation under a non-radical oxidation pathway. Singlet oxygen (1O2) was the dominated reactive oxygen species in the CuO-CeO2/PMS system, leading to a dramatical degradation efficiency with Rhodamine B (RhB) as model compounds. The observed rate constant of the CuO-CeO2/PMS system was 7–11 times higher than that of only PMS, CeO2/PMS and CuO/PMS systems. Also, under the reaction conditions of 1.6 mM PMS, 0.4 g/L catalyst and initial pH 7, the degradation efficiencies of RhB, Methylene Blue, Reactive Blue 19 and atrazine were respectively up to 100%, 85.39%, 72.84% and 98.44% in 60 min. X-ray photoelectron microscopy analysis indicated that the electrons transfer between CuO and CeO2 and the formation of oxygen vacancy in CeO2 should be responsible for the enhanced 1O2 production, which involved a new non-radical oxidation pathway for PMS activation by CuO-CeO2 catalyst. Moreover, the combination of CuO and CeO2 increased reusability and stability of catalyst, allowing it remove more than 92% of RhB over a wide pH range (pH = 3–9). This study not only proved that CuO-CeO2 is an efficient and stable PMS activator but also provided a new insight into PMS activation through a non-radical oxidation pathway for organic contaminants removal from wastewater.

Sewage sludge, one of the major byproducts from wastewater treatment plants (WWTPs), contains high contents of nutritional elements that can be recycled and reutilized to make up the overuse of limited resources on Earth. Currently, the reutilization ratio of sewage sludge is relatively low, most probably due to the high operation costs for its treatment and disposal in WWTPs. This study for the first time realized biogas upgrading, resources conservation and sludge conditioning simultaneously in one anaerobic digestion (AD) reactor for sewage sludge treatment through coupling biogas recirculation with MgCl2 addition. Results showed that 86% of methane content could be obtained by the intermittent biogas recirculation during AD. When MgCl2 was further added, soluble orthophosphate and ammonia nitrogen were reduced by 87% and 19% during 17 days’ AD. At the same time, around 120 mg/g-total solids (TS) of struvite was estimated to generate in the digested sludge, and the sludge dewaterability was enhanced by 37% when biogas recirculation was performed along with MgCl2 addition. At last, not only the enhanced electricity generation from biogas with higher methane content but also the increased fertilizer potential of the digestate were analyzed in the context of a local WWTP, reflecting the great potentials and profits of this novel AD system in industrial-scale sewage sludge treatment.

Hydrothermal treatment (HTT) has been recognized as a highly efficient technology for organics decomposition and energy/nutrients recovery from waste biomass. Up to now, however, the efficiency of HTT as the pre- and post-treatment of anaerobic digestion (AD) has not been well compared and documented. In this study, the effects of HTT as the pre- (strategy I, HTT + AD) and post-treatment (strategy II, 1st AD + HTT + 2nd AD) of AD of primary sludge were evaluated based on comparative experiments in regards to energy balance, nutrients transformation, and sludge dewaterability. Results show that the optimal HTT temperature was 130 °C for strategy I and strategy II according to the maximum methane production rate (μ) estimated from Gompertz model and the net energy gain (ΔQ) calculated. Although HTT as the post-treatment of AD achieved higher total methane yield and solids reduction, the increment of methane yield was found to be similar through both strategies compared to their control counterparts (no HTT). The decomposition of insoluble organic carbon was also similar via both strategies. Insoluble nitrogen fraction was detected to be the lowest (6.8%) after HTT at 190 °C in strategy II, comparable to that after HTT at 210 °C (∼10.0%) using strategy I. The proportion of bioavailable phosphorus was found to slightly decrease with the increase of HTT temperature in strategy II, probably due to the alkaline pH in the treated digestate. The sludge dewaterability indicated by specific resistance to filtration (SRF) showed a similar trend after AD under the tested conditions of both strategies, which was remarkably improved when HTT was performed at temperatures higher than 170 °C. HTT as the pre-treatment (strategy I) was found to be more energy efficient in comparison to HTT as the post-treatment (strategy II) of AD of primary sludge. In addition, a positive energy efficiency could be achieved when the sludge solids content ≥2.2%.

Cobalt hexacyanoferrate of various compositions was prepared in flow mode and the role of the vacancy on the structure, thermogravimetric (TG) properties, and the adsorption efficiency was studied. The material, Nay Co[Fe(CN)6 ]1-x ⋅z H2 O, with a minimum vacancy of x=0.014 to the highest x=0.47, was obtained. The TG-differential scanning calorimetry (DSC) profile showed a distinct influence of the vacancy on the water release temperature. Materials with x>0.35 showed a smooth release of water at a relatively lower temperature. However, for the materials with x

Helicteres angustifolia L. (H.angustifolia) is an important medicinal plant. This study investigated the phytochemical characteristics of callus suspension cultures of H.angustifolia and its bioactive functions, such as antioxidant, antidiabetic and immunomodulatory activities. Results demonstrated that the cultures were rich in phenolic compounds, flavonoids, terpenoids, saponins and triterpenoids. Compared to the equivalent wild roots, the cultures yielded larger amounts of total phenolics (17.75 mg GAE g− 1), flavonoids (56.15 mg RE g− 1), saponins (29.21 mg OAE g− 1) and polysaccharides (13.69 mg g− 1), about 1.62-, 1.90-, 1.14- and 3.41-fold higher than those from the equivalent wild roots, respectively. Furthermore, as the valuable target product from in vitro culture, phenolic compounds were subjected to HPLC analysis, reflecting that some representative phenolic compounds fluctuated significantly under the cultivation conditions. Additionally, bioactive assays showed that the extract of callus suspension cultures (CE) possessed strong antioxidant activities, and rat maltase (IC50 = 13.29 mg mL− 1) and sucrase (IC50 = 13.76 mg mL− 1) inhibitory activities. As for the immunomodulatory activity, CE could stimulate the proliferation of macrophages (121.93 ± 1.76%) and the production of nitric oxide (200% of the control) and phagocytic activity (178% of the control) at 6.25 μg mL− 1. Moreover, CE could mitigate DOX-induced macrophages damage to some extent. In conclusion, the callus suspension culture of H.angustifolia is a potential source for bioactive phytochemical compounds and functional foods.

To overcome the high separation cost of microalgae, natural microalgae granulation was performed in open sequencing batch reactors (SBRs) by treating synthetic wastewater. After operation for 60 days, easily settled algae granules were obtained with an average size of 0.61 mm, sludge volume index (SVI) of 125 ml/g and settling velocity of 12.2 m/h. More extracellular polymeric substances (EPS) (∼252 mg/g-VSS) were detected to excrete with a higher proteins/polysaccharides (PN/PS) ratio (∼7) for the algae granules on day 60, which are beneficial for granulation. Meanwhile, the algae granules were found to have a higher phosphorus (P) content (33.4 mg-P/g-TSS) with higher P bioavailability (91.8%) when compared to the seed algae (20.4 mg-P/g-TSS). The obtained algae granules possess great potential for P recovery and reuse.

Nanobubble water (NBW) has been applied in various fields due to the unique properties of nanobubbles (NBs) including long-term stability, negative zeta potential and generation of free radicals. In this study, the performance of four kinds of NBW from different gases (air, N2, H2, and CO2) in addition to deionized water (DW) were investigated and compared in terms of the growth of the probiotic Lactobacillus acidophilus 1028. The NB density, size distribution, zeta potential, pH and dissolved oxygen (DO) of the NBW were firstly investigated. Results indicate that N2-NBW had the highest absolute value of zeta potential and NB density (−25.3 ± 5.43 mV and 5.73 ± 1.0 × 107 particles per mL, respectively), while the lowest was detected in CO2-NBW (−6.96 ± 2.36 mV and 3.39 ± 1.73 × 107 particles per mL, respectively). With the exception of CO2-NBW, all the other types of NBW showed promotion effects on the growth of the strain at the lag and logarithmic phases. Among them, N2-NBW demonstrated the best performance, achieving the highest increase ratio of 51.1% after 6 h cultivation. The kinetic models (Logistic and Gompertz) indicate that the culture with N2-NBW had the shortest lag phase and the maximum specific growth rate when compared to the H2-NBW and DW groups under the same cultivation conditions. Preliminary analysis on the mechanisms suggested that these effects were related to the properties (zeta potential and density) of the NBs, which might affect the transport of substances. This study suggests that NBW has the potential for promoting the production efficiency of probiotics via fermentation.

The effects of organic loading rate (OLR) on simultaneous phosphorus (P) and alginate-like exopolymers (ALE) recovery from bacterial aerobic granular sludge (AGS) and algal-bacterial AGS were examined and compared during 70 days' operation. With the increase of OLR (0.6-1.2 g COD/(L·day)), both AGS showed good settleability and granular strength with P bioavailability 92% (Stage III). The moderate increase in OLR had a positive influence on simultaneous recovery of P and ALE. On day 60, the contents of ALE and guluronic acid/guluronic acid (GG) blocks reached the highest in algal-bacterial AGS, about 13.37 and 2.13 mg/g-volatile suspended solids (VSS), respectively. Meanwhile, about daily 0.55 kg of P is estimated to be recovered from the wastewater treatment plant with a treatment capacity of 10,000 m

Energy self-sufficient wastewater treatment designs can reduce net energy consumption and achieve resources recovery. Microalgae are regarded as a promising candidate for developing a circular bioeconomy in wastewater treatment plants (WWTPs) due to its potential for simultaneous wastewater remediation and high value-added materials production. Much effort has been made to overcome the high production costs for microalgae; however, biomass harvesting still remains as the bottleneck for its large-scale application. In this study, the novel biogranulation system facilitating easier and faster microalgae harvesting was firstly compared with the conventional suspended culture for energy-efficiency and sustainability assessment on microalgae (Ankistrodesmus falcatus var. acicularis) cultivation using the synthetic anaerobic digestion liquor. Results demonstrated that the biogranulation system enhanced volumetric biomass productivity (223.17 ± 11.82 g/m3/day) by about 4.4 times compared to that from the suspended system (41.57 ± 2.08 g/m3/day) under the same environmental conditions. It was noticed that lipids, carbohydrates and proteins were accumulated in microalgae cells along with nutrients remediation, and the microalgae granules with much higher proteins content (313.28 ± 26.67 mg/g-VSS) could be easily harvested through 2 min gravity sedimentation with little impact on the contents of carbohydrates and lipids. In the whole cultivation and harvesting process, the biomass mass-based electricity consumption and footprint demand by the biogranulation system were reduced by 58% and 76%, respectively. Results from this study provide a cost-effective and sustainable approach for microalgae in the treatment of nutrients rich digestion liquor with simultaneous production of valuable biomaterials. This work was supported by JSPS KAKENHI Grant Number JP18H03403. Ms. Qian Wang would like to thank the financial support from the China Scholarship Council (No. 201808050110) for her PhD study in University of Tsukuba, Japan.

Algal-bacterial aerobic granular sludge (AGS) was applied for hexavalent chromium (Cr(VI)) biosorption from wastewater and the dynamic distribution and mobility of different metals in granules were systematically examined before and after hydrothermal treatment. The loaded Cr on algal-bacterial AGS was found to mainly localize in microbial cells and mineral particles; little Cr was detected in extracellular polymeric substances (EPS) after 6 h contact, which increased to 5.1% after 24 h biosorption. Along with Cr localization, 9.3-22.8% of Mg and 11.5-26.4% of Ca in algal-bacterial AGS were released from loosely bound EPS, then replenished to maintain their stable proportion in EPS, probably contributing to granular stability. In addition, chemical fractionation showed that the Cr mobility in algal-bacterial AGS, indicated by a low mobility factor of 4.7%, decreased to 1.4% with the co-existence of mineral salts and acetate during biosorption, which was further declined to 0 after hydrothermal treatment.

Zero-valent iron (ZVI) supplementation for improving anaerobic digestion (AD) of ammonia-rich swine manure (initial ammonia-N ∼5000 mg/L) was tested. The addition of 5 g/L ZVI powder apparently accelerated the acidification process to produce more volatile fatty acids (VFAs) and optimized the fermentation type by contributing to a lower system oxidation–reduction potential (ORP) level of −181.7 to −250.0 mV favorable for ethanol-type and butyric-type fermentation during day 14–30, in comparison with that of −164.3 to −216.3 mV in the control group favorable for propionic-type. Overall, ZVI significantly decreased the proportion of propionic acid from 49.8% to 30.9% while increased the proportion of n-butyric acid from 6.8% to 18.7%. Microbial analysis revealed that fast growing and ammonia-tolerant hydrogenotrophic Methanoculleus species were enriched with ZVI, helping achieve a 54.2% higher CH4 yield relative to control. Results from this study demonstrated the potential of ZVI addition to enhance AD of ammonia-rich animal manure.

Resistant pollutants like oil, grease, pharmaceuticals, pesticides, and plastics in wastewater are difficult to be degraded by traditional activated sludge methods. These pollutants are prevalent, posing a great threat to aquatic environments and organisms since they are toxic, resistant to natural biodegradation, and create other serious problems. As a high-efficiency biocatalyst, enzymes are proposed for the treatment of these resistant pollutants. This review focused on the roles and applications of enzymes in wastewater treatment. It discusses the influence of enzyme types and their sources, enzymatic processes in resistant pollutants remediation, identification and ecotoxicity assay of enzymatic transformation products, and typically employed enzymatic wastewater treatment systems. Perspectives on the major challenges and feasible future research directions of enzyme-based wastewater treatment are also proposed.

In this study, chromium (Cr) was used as an example of the most toxic heavy metals that threaten human health, and Cr(VI) bioremediation was implemented by using a new type of aerobic granular sludge (AGS), i.e., algal-bacterial AGS. Results showed that the total Cr removal efficiency by active algal-bacterial AGS was 85.1 ± 0.6% after 6 h biosorption at pH 6 and room temperature, which could be further improved to 93.8 ± 0.4% with external electron donor (glucose) supply. However, inactivation dramatically decreased the total Cr removal efficiency to 29.6 ± 3.5%, and no effect was noticed when external electron donor was provided. With an antibiotic (levofloxacin) or metabolic inhibitor (NaN3) addition, the total Cr removal efficiency of bacterial AGS was inhibited by 16.0% or 10.1%, but this efficiency was maintained in the case of algal-bacterial AGS. Analysis of extracellular polymeric substances (EPS) composition revealed that under Cr(VI) exposure, more loosely bound EPS were secreted by algal-bacterial AGS, favoring Cr(VI) reduction. Results from chemical fractionation indicated that 90.5 ± 4.2% of the loaded Cr on algal-bacterial AGS was in an immobile form, reflecting the low environmental risk of Cr-loaded algal-bacterial AGS after biosorption of hazardous heavy metals from wastewater.

Cordyceps militaris possesses several compounds with medicinal properties, and is commonly used in traditional Chinese functional food and medicine for a variety of health benefits. Because of its rare occurrence in nature, the market demand for artificial C. militaris is on the rise. Furthermore, efforts to increase its bioactive ingredients have also been considered in research. In this study, we aimed to investigate the effect of fluoride on the growth and enrichment of bioactive compounds in C. militaris. A wide range of potassium fluoride concentrations (0, 0.001, 0.01, 0.1, and 1 mM) were added to the culture media as a source of fluoride during the cultivation of C. militaris fruiting bodies. The contents of fluorine and bioactive substances of the fruiting bodies in normal (NM) and fluorine-supplemented (FM) media were measured and compared. C. militaris raised in the growth medium supplemented with 0.01 mM potassium fluoride led to a 44.86% (1.55 ± 0.14 g/bottle) increase in biomass and a 23.43% (3161.38 ± 35.71 µg/g) increase in total carotenoid content in the fruiting bodies. Furthermore, a remarkable increase in superoxide dismutase-like activity (84.75 U/mg) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (IC50 = 2.59 mg/mL) was recorded. In human cancer cell-based assays, C. militaris raised in FM caused stronger cytotoxicity, apoptosis, and cell cycle arrest in human osteosarcoma cells. These results demonstrated that a low dose of fluoride could stimulate the growth of C. militaris fruiting bodies and enhance the production of bioactive ingredients that possess useful antioxidant and anticancer activities.

Wastewater treatment plants are particularly challenging with the treatment and disposal of sewage sludge produced from the treatment units due to its high costs and environmental hazards. In this study, a biogas recirculation-driven anaerobic digestion (AD) system was developed with upward shear force being provided by biogas recirculation coupled with the alkali addition strategy, targeting biogas upgrading, sludge stabilization, and sludge flocculation simultaneously, thus reducing the sludge management costs. Compared to the conventional AD system, the novel biogas recirculation-driven AD system could achieve biogas upgrading with 10% higher CH4 content. Besides, the combination of NaOH and Ca(OH)2 addition strategy obviously improved sludge settleability and dewaterability compared to the single NaOH addition strategy. Owing to the attraction between negatively charged sludge particles and Ca2+ ions, the available Ca2+ in the former AD system may facilitate the re-flocculation and P immobilization in solid digestate, fix partial CO2 with less CO2 emission, and bridge with some sludge flocs. Moreover, 12.6% lower net cost for sludge management was achieved by this biogas recirculation-driven AD system together with the combination alkali addition strategy, which is regarded as a promising integrated multi-purpose system for sludge treatment.

Hexavalent chromium (Cr(VI)) is one of the typical heavy metals that pose a great threat to the environment. As a novel biotechnology, algal-bacterial aerobic granular sludge (AGS) possesses the merits of both bacterial AGS and algae. This study firstly evaluated Cr(VI) removal via biosorption by algal-bacterial AGS under different operation conditions and then some environmental factors. Results show that the highest Cr(VI) reduction (99.3%) and total Cr removal (89.1%) were achieved within 6 h at pH 2 and 6, respectively. The coexisting oxyanions exhibited slight effects, while both tested natural organic matters (humic acid and tannic acid) and carbon sources promoted Cr(VI) reduction at some appropriate concentrations. The coexistence of metal cations favored Cr(VI) reduction, achieving the highest enhancement of 8.1% by Cu2+ at 5 mg/L, while the total Cr removal was suppressed to some extent. Salinity > 5 g/L severely inhibited both Cr(VI) reduction and total Cr removal. Moreover, the loaded Cr in algal-bacterial AGS was found to be almost in the form of Cr(III), with 66.8% being contributed by intracellular accumulation. This work suggests that Cr(VI) reduction and intracellular accumulation are the main mechanisms involved in Cr(IV) biosorption onto algal-bacterial AGS.

Nano-bubble water (NBW) has been proven to be effective in promoting organics utilization and CH4 production during anaerobic digestion (AD) process, suggesting its potential in improving the stability of the AD process and thereby alleviating acidic inhibition. In this work, the effect of NBW on digestion stability and CH4 production was investigated to evaluate the ability of NBW on AD recovery from acidic inhibition. Results showed that NBW supplementation increased the total alkalinity (TA) and partial alkalinity (PA), and reduced the ratio of VFA/TA, thus maintained the stability of the AD process. Generation/consumption of VFAs was also enhanced with NBW supplementation under acidic inhibition with pH values of 5.5, 6.0 and 6.5. The cumulative CH4 production was 246–257 mL/g-VS in NBW groups, which was 12.1–17.2% higher than the control. Moreover, with NBW supplementation, the maximum CH4 production rate was raised according to the modeling results.

This study aimed to figure out the main contributors to aerobic phosphorus (P) removal in the algal-bacterial aerobic granular sludge (AGS)-based wastewater treatment system. Kinetics study showed that aerobic P removal was controlled by macropore (contributing to 64-75% P removal) and micropore diffusion, and the different light intensity (0, 4.0, 12.3, and 24.4 klux) didn't exert significant (p 0.05) influence on P removal. On the other hand, the increasing light intensity did promote microalgae metabolism, leading to the elevated wastewater pH (8.0-9.8). The resultant pH increase had a strongly negative relationship (R

Algal-bacterial aerobic granular sludge (AB-AGS) as a symbiosis system possesses high potential for being operated without external O

This study investigated the enhancement effect of N2- and Air-nanobubble water (NBW) supplementation on two-stage anaerobic digestion (AD) of food waste (FW) for separate production of hydrogen and methane. In the first stage for hydrogen production, the highest cumulative H2 yield (27.31 ± 1.21 mL/g-VSadded) was obtained from FW + Air-NBW, increasing by 38% compared to the control (FW + deionized water (DW)). In the second stage for methane production, the cumulative CH4 yield followed a descending order of FW + Air-NBW (373.63 ± 3.58 mL/g-VSadded) > FW + N2-NBW (347.63 ± 7.05 mL/g-VSadded) > FW + DW (300.93 ± 3.24 mL/g-VSadded, control), increasing by 24% in FW + Air-NBW and 16% in FW + N2-NBW compared to the control, respectively. Further investigations indicate that different gas–NBW may positively impact the different stages of AD process. Addition of N2-NBW only enhanced the hydrolysis/acidification of FW with no significant effect on methanogenesis. By comparison, addition of Air-NBW promoted both hydrolysis/acidification stage and methanogenesis stage, reflecting by the enhanced activities of four extracellular hydrolases at the end of hydrolysis/acidification and coenzyme F420 at the end of methanogenesis, respectively. Results from this work suggest the potential application of Air-NBW in the two-stage AD for efficient renewable energy recovery from FW.

Various kinds of vanadium (V) ore mining areas produced serious contamination have been widely recognized, while less relevant research was about the associated health risk and V distribution level for farmland soils around. This study assessed the contamination characteristics and associated human health risk of V in the surface farmland soils near various V ore mining areas. The bioremediation of V contamination by indigenous microbes from them was also evaluated. The farmland soils near stone coal area (Hunan province, China) showed the highest mean concentration of V (543.91 mg/kg), posing high non-carcinogenic risks, with high hazard quotient (HQ) value of 1.29 for children. While, V values of sampled soils near V titanomagnetite, petroleum associated minerals and uvanite areas were lower than that near stone coal area, also with lower HQ values (1.00). Within 60 h, the removal efficiency of V(V) reached 98.4% with farmland soils near uvanite area, suggesting feasibility of V bioremediation via indigenous microbes. Bacterial communities after long-term cultivation (240 d) with V(V) were dominated by native microbes able to tolerate or reduce the toxicity of V(V), such as Ruminococcaceae_incertae_sedis, Trichococcus and Comamonas. This work is helpful for calling attention to V pollution of farmland near various V ore mining areas and formulating effective strategies for V(V) contamination bioremediation.

The high costs involved in sewage sludge treatment and disposal in wastewater treatment plants (WWTPs) not only bring about improper sludge disposal and thus environmental pollutions, but also limit the investment on construction of WWTPs, especially in rural areas or low-income regions. This comparative study examined the effect of biogas recirculation coupled with chemical addition in a semi-continuous anaerobic digester for sludge treatment, which was proven to achieve biogas upgrading, phosphorus conservation and sludge conditioning simultaneously, largely reducing the sludge treatment cost. Results show that FeCl

In this study, high solid anaerobic digestion of pig manure (PM) under nano-bubble water (NBW) addition was investigated with focus on digestion stability, methanogenesis performance and related mechanisms. Volatile fatty acids (VFAs) inhibition occurred when total solids (TS) was about 8% without NBW addition, which was alleviated with improved digestion stability under NBW addition, facilitating the process of high solids anaerobic digestion (HSAD). The cumulative CH4 yield, on the other hand, was 201–230 mL/g-VS in the NBW reactors at TS of 3–6%, about 20.3–25.0% higher than the control reactors. At the same time, with higher water mobility and zeta potential, NBW was found to promote the consumption of soluble proteins/carbohydrates during the above AD process.

This study investigated the synergistic effects of rice straw (RS) and rice bran (RB) addition on methane production and process stability of anaerobic digestion of food waste (FW). Positive synergistic effect (Synergy index (SI) = 1.03–1.24 > 1) was noticed in all the co-digestion reactors. The optimum mixing ratio of FW:RS:RB (volatile solid (VS) basis) was 60:10:30 with the maximum SI (1.24), achieving 27.4% increase in methane yield (235.4 mL/g-VS) and around 5 days shorter of λ (3.7 days) compared to the mono-digestion of FW (184.8 mL/g-VS and 8.2 days). Remarkably high concentration of volatile fatty acids (VFAs) was also accumulated in the mono-digestion of FW, especially propionic acid, which to a great extent caused the methane production to stagnate. Results from this study demonstrate that co-digestion of FW and RS with RB has high potentials for energy recovery from AD of the mixed feedstocks and its stable operation.

Sustainable sewage sludge management is a worldwide issue in wastewater treatment plants (WWTPs). This work developed a new strategy for sewage sludge treatment involving the integration of hydrothermal treatment (HT) with anaerobic co-digestion (AcoD), particularly on the feasibility of mesophilic AcoD of anaerobically digested sludge (DS) hydrolysate and waste activated sludge (WAS). Results show that AcoD of DS hydrolysate from HT 170℃ for 30 min with WAS achieved the highest CH4 production of 205.39 mL CH4/g-VSfed. By adopting the new AD-HT170-AcoD strategy, 61.88 mL CH4/g-tVSfed higher CH4 yield and 22.2% more total solids (TS) reduction were obtained in addition to much better sludge settleability and 7.6% wt. less sludge cake production compared to the conventional mono AD. Although negative energy gain was obtained, the proposed AD-HT170-AcoD strategy is promising, economically feasible, and sustainable when the final sludge disposal of WAS is concerned in the context of whole WWTP.

Nitrite removal is necessary and significant for pickle and meat processing wastewater. In this study, Chlorella sp. L38 is used as an alternative to remove nitrite and reuse it as nitrogen source for potential value-added ingredients production. Based on the typical BG11 medium with and without NaNO3 (which is the conventional nitrogen source), nitrite is additionally provided, and its concentration gradient was set at 0, 50, 100, 150 and 200 μmol/L, respectively. The experimental results showed that the nitrite removal rate could achieve 57.1 μmol/L/d. In addition, the biomass variation, and value-added ingredients (polysaccharides, lipid, and protein) productivity were also measured, and their yield could achieve 4.8 mg/g/d, 3.0 mg/L/d and 5.5 mg/L/d, respectively. It indicated that Chlorella sp. L38 has the potential to be an environmentally friendly approach for nitrite removal of wastewater.

Nanobubble water (NBW) has been proven to efficiently improve methane production from organic solid wastes. However, the increase in reactor volume due to addition of NBW hinders its practical applications. In this study, anaerobically digested sludge was first pre-augmented by N2-NBW and O2-NBW using corn straw as sole substrate for methane production with electron transfer activity being monitored. 20%, 33% and 38% of cellulose and 29%, 35% and 35% of hemicellulose were reduced respectively from the control, N2-NBW and O2-NBW pre-augmented sludge reactors. N2-NBW and O2-NBW pre-augmented sludge reactors achieved methane yields of 127 and 142 mL/g-VS, about 10% and 22% higher than that from the control. Results show that use of NBW pre-augmented anaerobically digested sludge as inoculum can remarkably enhance methane yield from corn straw, providing a novel concept for NBW-based anaerobic digestion system with no increase of reactor volume and construction cost in practice.

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The effect of a tubular reactor design on nutrients removal and granular stability of algal-bacterial aerobic granular sludge (AB-AGS) was investigated. A batch tubular reactor and a column reactor were operated in parallel under different upflow air velocities, i.e., 1, 0.5 and 0 cm/s to compare their performance. Due to the virtue of its geometry, the tubular reactor required 3.25 times lower aeration rate as compared to the column reactor. Experimental results showed that even under lower aeration rates, the nutrients removal efficiency by the tubular reactor remained almost similar to the column reactor. A upflow air velocity of 0.5 cm/s provided the optimum condition for granular stability, achieving 83.5% of dissolved organic carbon removal and 71.5% of total nitrogen removal by the tubular reactor. There was a marked increase in chlorophyll a concentration in the tubular reactor, indicating faster algae growth, which could be attributed to the better light incidence capacity of the reactor design. Thus, a tubular reactor design can be a viable alternative for a novel low aeration wastewater treatment system.

Combined effect of zero valent iron (ZVI) and magnetite on semi-dry anaerobic digestion of swine manure was studied. Compared with control, the addition of 5 g/L ZVI, magnetite and their mixture (1:1 wt.) increased the CH4 yield by 17.6%, 22.7% and 21.9%, respectively. The three additives improved CH4 production through altering the metabolism pathways, rather than improving the solid degradation efficiency. ZVI promoted interspecies hydrogen transfer (IHT) by enriching H2-comsuming Methanolinea and acetate-oxidizing bacteria (Sedimentibacter and Clostridium). Magnetite enriched dissimilatory iron reduction bacteria (Acinetobacter) to accelerate organic hydrolysis and established direct interspecies electron transfer (DIET) by enriching Methanothrix and Methanospirillum. Key microorganisms relative to IHT (Clostridium) and DIET (Methanothrix and Methanospirillum) were simultaneously enriched with ZVI+magnetite, but they only showed an additive effect on methanogenesis, the lack of synergetic effect was attributable to the possible trade-off between IHT and DIET, or the little improvement effect of additives on substrate biodegradability.