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Sulfur autotrophic denitrification (SAD) occurs without organic carbon sources, offering advantages in removing nitrogen pollutants from water with low carbon to nitrogen ratio. However, ensuring nitrate–reducing sulfide–oxidizing bacteria ability to access the necessary sulfur and inorganic carbon sources is a challenge. Therefore, this study investigated the feasibility of utilizing a SAD composite filler to mitigate nitrogen and phosphorus pollutants concentrations in secondary effluent of wastewater treatment plants (WWTPs) and reduce eutrophication risk in the receiving water. The use of paraffin optimized composite filler with a satisfying 3.70 % break rate and wear rate without dramatically deteriorating contaminant removal performance. The process achieved 94.26 % total nitrogen (TN) and 90.91 % PO 4 3--P removal rates in treating synthetic wastewater; and 2.72 ± 1.92 mg/L and 0.29 ± 0.06 mg/L of TN and PO 4 3--P discharge in treating WWTPs secondary effluent, respectively. The results indicated that denitrification performance of the filler was primarily influenced by variations in NH 4 +-N resulting from SAD and dissimilatory nitrate reduction to ammonia caused by differences in filler composition and preparation factors. Based on the performance difference in SAD, Fex + leached by H+ in the filler changed, affecting phosphorus removal performance. The change in mechanical properties of the filler was primarily dependent on the surface characteristics of the filler and the content/type of the binder. This study demonstrates the feasibility of using SAD for advanced nitrogen and phosphorus removal from wastewater and applying sulfur/siderite integrated composite filler as a pilot, thereby offering insights for the preparation of SAD fillers. [Display omitted] • Enhanced composite filler was piloted for sulfur autotrophic denitrification (SAD). • 37.30 % NH 4 +-N in the effluent was reduced after filler was optimized. • Phase change material served as a distributer and an extra binder for materials. • Low paraffin addition (2 % wt) reduced filler break rate and wear rate by 20.94 %. [ABSTRACT FROM AUTHOR]

In recent years, with the global rise in awareness regarding carbon neutrality, the treatment of wastewater in rural areas is increasingly oriented towards energy conservation, emission reduction, low-carbon output, and resource utilization. This paper provides an analysis of the advantages and disadvantages of the current low-carbon treatment process of low-carbon treatment for rural wastewater. Constructed wetlands (CWs) are increasingly being considered as a viable option for treating wastewater in rural regions. In pursuit of carbon neutrality, advanced carbon-neutral bioprocesses are regarded as the prospective trajectory for achieving carbon-neutral treatment of rural wastewater. The incorporation of CWs with emerging biotechnologies such as sulfur-based autotrophic denitrification (SAD), pyrite-based autotrophic denitrification (PAD), and anaerobic ammonia oxidation (anammox) enables efficient removal of nitrogen and phosphorus from rural wastewater. The advancement of CWs towards improved removal of organic and inorganic pollutants, sustainability, minimal energy consumption, and low carbon emissions is widely recognized as a viable low-carbon approach for achieving carbon-neutral treatment of rural wastewater. This study offers novel perspectives on the sustainable development of wastewater treatment in rural areas within the framework of achieving carbon neutrality in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

Anaerobic membrane bioreactor (AnMBR) technology has great advantages for treating urban wastewaters, but, when irrigation cannot be applied and the effluent is discharged in a sensitive zone, a post-treatment of this effluent is needed for nitrogen and phosphorus removal. Under this scenario, ion exchange processes represent one of the most promising technologies for treating this effluent. Ion exchange technology allows to meet discharge limits and to recover these nutrients in a highly concentrated stream. In this work, the technical feasibility of using a commercial resin for phosphorus recovery and a natural zeolite (clinoptilolite) for nitrogen recovery was evaluated. Purolite FerrIX A33E resin removed phosphate from the AnMBR permeate within 500 Bed Volumes (BVs) with a maximum adsorption capacity (q max) of 2,1 mg P-PO 4 /g resin. Regeneration of the resin (2% NaOH 2% NaCl) recovered over 95% of the phosphorous retained, achieving a concentration of 316,7 mg P-PO 4 /L in the regeneration solution. In the absence of a long-term study, the resin showed a stable adsorption capacity during 16 cycles of saturation-regeneration. Clinoptilolite removed nitrogen within 139 BVs obtaining a q max of 3,68 mg N-NH4/g zeolite. 97 % of the retained N-NH 4 was recovered in the regeneration stage (0,8% NaOH) with an average concentration of 577 mg N-NH 4 /L. Continuous exposure of the zeolite to alkaline solutions led to reduction of 50% of the adsorption capacity after 17 cycles. [Display omitted] • Purolite FerrIX A33E concentrates P, allowing its recovery through crystallization. • No decrease in P adsorption capacity was observed within 16 cycles. • Purolite SSTC60 showed higher affinity for divalent than monovalent cations. • Clinoptilolite concentrates N, allowing its recovery through membrane contactors. [ABSTRACT FROM AUTHOR]

Wastewater treatment processes significantly contribute to greenhouse gas (GHG) emissions. Municipal wastewater treatment also faces challenges related to low strength and a low carbon-to-nitrogen (C/N) ratio. This study investigates the high-carbon tofu wastewater flowing into municipal sewers for co-treatment at a wastewater treatment plant (WWTP) directly, with the goal of enhancing nitrogen removal and reduce GHG emissions. Within the framework of a circular economy for wastewater treatment, tofu wastewater serves as an external carbon source for sustainable solutions. The concentrated tofu wastewater had an average chemical oxygen demand (COD Cr) of 21,894 ± 11,485 mg/L, total nitrogen (TN) of 591.8 ± 238.2 mg/L, and a C/N ratio of 36.9 ± 7.4. The denitrification rate reached 3.05 mg NO 3 −-N/(g MLVSS·h). Therefore, tofu wastewater is a suitable alternative carbon source. A full-scale WWTP with a capacity of 20,000 m³/day was monitored from 2017 to 2022 to evaluate the co-treatment effects of municipal wastewater and tofu wastewater. The results showed an increase in 53.3% in the average COD Cr concentration of the influent wastewater, while the total nitrogen and total phosphorus removal efficiencies were enhanced to 75.8% and 95.2%, respectively. In addition, the study quantified GHG emissions from tofu wastewater and municipal wastewater treatment. Compared to separate treatment processes, the co-treatment reduced GHG emissions by 337.9 t CO 2 -eq., approximately 15.8% of the total emissions of WWTP, and achieved a cost saving of 7–10% of the total operational costs. These findings demonstrate the environmental and economic advantages of integrating high-carbon industrial wastewater treatment directly into wastewater treatment plants. [Display omitted] • Untreated Tofu wastewater flowing into WWTP to increase carbon source was proposed. • Tofu wastewater enhanced treatment efficiency of municipal wastewater with low C/N. • Co-treatment patterns reduced greenhouse gas emissions and operational costs. • It offers a reference for developing high-carbon wastewater utilization policies. [ABSTRACT FROM AUTHOR]

Treatment Wetlands (TWs) are widely used for the treatment of domestic wastewater, with an increasing emphasis on provision of multiple co-benefits. However, concerns remain regarding achieving stringent phosphorus (P) discharge limits, system robustness and resilience, and associated guidance on system design and operation. Typically, where P removal is intended with a passive TW, surface flow (SF) systems are the chosen design type. This study analysed long-term monitoring datasets (2–30 years) from 85 full-scale SF TWs (25 m2 to 487 ha) treating domestic sewage with the influent load ranging from 2.17 to 54,779 m3/d, including secondary treatment, tertiary treatment, and combined sewer overflows treatment. The results showed median percentage removals of total P (TP) and orthophosphate (Ortho P) of 28% and 31%, respectively. Additionally, median areal mass removal rates were 5.13 and 2.87 gP/m2/yr, respectively. For tertiary SF TWs without targeted upstream P removal, 80% of the 44 systems achieved ≤3 mg/L annual average effluent total P. Tertiary SF TWs with targeted upstream P removal demonstrated high robustness, delivering stable effluent TP < 0.35 mg/L. Seasonality in removal achieved was absent from 85% of sites, with 95% of all systems demonstrating stable annual average effluent TP concentrations for up to a 30-year period. Only two out of 32 systems showed a significant increase in effluent TP concentration after the initial year and remained stable thereafter. The impact of different liner types on water infiltration, cost, and carbon footprint were analysed to quantify the impact of these commonly cited barriers to implementation of SF TW for P removal. The use of PVC enclosed between geotextile gave the lowest additional cost and carbon footprint associated with lining SF TWs. Whilst the P-k-C* model is considered the best practice for sizing SF TWs to achieve design pollutant reductions, it should be used with caution with further studies needed to more comprehensively understand the key design parameters and relationships that determine P removal performance in order to reliably predict effluent quality. [Display omitted] • Phosphorus removal from sewage in 85 full-scale surface flow wetlands was evaluated. • Most systems showed no seasonal variation in effluent phosphorus concentrations. • Effluent TP ≤ 3 mg/L in 80% of tertiary wetlands without targeted upstream P removal. • 96% of all tertiary treatment systems had no start-up period for phosphorus removal. [ABSTRACT FROM AUTHOR]

Glycerol, an abundant by-product of biodiesel production, represented a promising carbon source for enhancing nutrient removal from low C/N ratio wastewater. This study discovered a novel approach to initiate glycerol-driven denitrifying phosphorus removal (DPR) in situ by creating a short-term microaerobic environment within the aerobic zone. This approach facilitated the in-situ conversion of glycerol, which was subsequently utilized by denitrifying phosphate accumulating organisms (DPAOs) for DPR. The feasibility and stability of glycerol-driven DPR were validated in a continuous-flow pilot-scale reactor. Anaerobic phosphorus release increased from 1.0 mg/L/h to 2.5 mg/L/h, with fermentation bacteria and related functional genes showing significant increases. The stable stage exhibited 92.8% phosphorus removal efficiency and 55.5% DPR percentage. The microaerobic environment enhanced fermentation bacteria enrichment, crucial for glycerol-driven DPR stability. The collaborative interaction between fermentation bacteria and phosphate accumulating organisms (PAOs) played a key role in sustaining glycerol-driven DPR stability. These findings provide a robust theoretical foundation for applying glycerol-driven DPR in established wastewater treatment plants. • The start-up of glycerol-driven DPR was systematically studied. • The microaerobic environment promoted the in situ conversion of glycerol into VFAs. • Highly efficient P removal (92.8%) and DPR% (55.5%) were achieved. • The synergy of fermentative bacteria and PAOs maintained the stability of DPR. [ABSTRACT FROM AUTHOR]

Landfill leachate is an important source of microplastics (MPs) and antibiotic-resistance genes (ARGs). Here, in the presence of polystyrene MPs (PS-MPs) and polyethylene MPs (PE-MPs), the nitrogen and phosphorus removal effect and sludge structure performance were affected in an anaerobic–anoxic–aerobic system, a typical biological leachate treatment process. The abundance of tetracycline-resistance genes (tet genes) in biofilms on the two types of MP was significantly higher than that in the leachate and sludge, and the load on PE-MPs was higher than that on PS-MPs because of the porous structure of PE-MPs. Aging of the MPs increased their surface roughness and abundance of oxygen-containing functional groups and shaped the profile of ARGs in the MP biofilms. The biofilm biomass and growth rate on the two types of MP increased with the incubation time in the first 30 days, and was affected by environmental factors. Structural equation models and co-occurrence network analysis demonstrated that the MPs indirectly affected the spectrum of ARGs by affecting biofilm formation, and, to a lesser extent, had a direct impact on the selective enrichment of ARGs. We discuss the mechanisms of the relationships between MPs and ARGs in the leachate treatment system, which will have guiding significance for future research. Our data on the colonization of microorganisms and tet genes in MPs biofilms provide new evidence concerning the accumulation and transmission of these ARGs, and are important for understanding the mechanisms of MPs in spreading pollution. [Display omitted] • The tet genes was enriched on the MPs biofilm and it boosted in leachate and sludge. • The aging of MPs shaped the profile of ARGs and ARB on MPs biofilm. • MPs reduced the richness and diversity of microbial community in A/A/O. • MPs integrated regulatory environmental factors to assemble ARGs and ARB. • Enhanced biochemical resistance and pathogens aggravated the MPs pollution. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) based adsorbents derived from waste sludge were utilized to remediate mixed contaminants in wastewater as an integrated waste-to-resource approach promoting a paradigm shift in management of refuse sludge and wastewater. This review specifically focuses on the remediation of constituents of landfill leachate by sludge-based activated carbon (SBAC). The adsorption effectiveness of SBAC for the exclusion of leachate characters including heavy metals, phenols, dyes, phosphates, and phosphorus were explored with regard to modifiers such as pH, temperature, properties of the adsorbent including functional groups, initial doses of absorbent and adsorbate, and duration of exposure to note the impact of each parameter on the efficiency of adsorption of the sludge adsorbent. Through the works of various researchers, it was noted that the properties of the adsorbent, pH and temperature impact the working of SBACs. The pH of the adsorbent by influencing the functional groups. Temperature was expected to have a paramount effect on the adsorption efficiency of the SBACs. The importance of the regeneration and recycling of the adsorbents as well as their leachability is highlighted. Sludge based activated carbon is recommended as a timely, resource-efficient, and sustainable approach for the remediation of wastewater. [Display omitted] • This article emphasizes leachate remediation by Sludge-based Activated Carbon. • The manufacturing of SBAC from waste sludge presents an efficient waste-to-resource technique. • Process parameters impacting the adsorption efficacy of sludge adsorbents have been discussed. • Regeneration and Leachability of sludge adsorbents has been discussed. • This review also enumerates the Economic feasibility and Life Cycle Analysis of sludge biochar. [ABSTRACT FROM AUTHOR]

The effective purification of phosphate-containing wastewater is considered as increasingly important. In this study, a highly effective LC-CNT film was developed for efficient phosphate removal. Kinetic results showed that the adsorbent exhibited an improved mass transfer efficiency and a fast adsorption rate during adsorption (reaching 80% and 100% equilibrium adsorption capacity within 175 and 270 min, respectively). Kinetic model analysis suggested that the adsorption was a combined chemical physical process. Isotherm study revealed that the LC-CNT film showed a superior adsorption capacity (178.6 mg/g, estimated from the Langmuir model) with multiple adsorption mechanisms. pH study suggested that surface complexation and ligand exchange played important roles during adsorption, and the adsorbent worked well within the pH range of 3–7 with little La leakage. The ionic strength and competing anions showed little influence on the adsorbent effectiveness except for the carbonate and sulfate ions. The characterization and mechanism study revealed that the phosphate adsorption of the LC-CNT film was controlled by inner-sphere complexation, outer-sphere complexation and surface precipitation. The LC-CNT film also showed excellent regenerability and stability in cycling runs, further demonstrating its potential in industrial applications. [Display omitted] • A novel LC-CNT film was developed with fast adsorption rate and high adsorption capacity. • External and internal surface adsorption occurred simultaneously during adsorption. • Phosphate uptake consisted of uniform (physical) and non-uniform (chemical) adsorption. • LC-CNT film showed stable performance in aqueous solution under different situation. • Adsorption mechanisms include inner- and outer-sphere complexation and surface precipitation. [ABSTRACT FROM AUTHOR]

Phosphate holds a critical role as a vital, limited, strategic, and irreplaceable resource. Throughout its production chain, residual phosphate can be found in waste streams. This study aims to enhance production efficiency by exploring methods to limit residual phosphate presence in waste stocks. It investigates the presence of residual phosphate in a phosphate mining site. The presence of residual phosphate throughout the production chain is investigated. Through meticulous analyses of extraction, destoning, and screening processes, the study identifies three primary stages where residual phosphate exists, the study simulates different scenarios of residual phosphate recovery and prevention. The principal data sources are data from mining site, recent literature, and information from a lithological log, the study meticulously analyzes the extraction, crushing, and sieving processes to assess the persistence of residual phosphate. The production chain diagnostic revealed that 76% of resource present is recovered (either integrated into the value chain or stored in the mine for future use), from which 8% goes to the destoning waste rocks (75% of which is residual phosphate) and the screening waste rocks (72% of which is residual phosphate), with an average grade that reaches 25% P 2 O 5. Approximately, 24% of the initial phosphate rock (with an average grade of 22% P 2 O 5) remains as residual phosphate which is retained in the spoil piles. To recover and prevent the presence of residual phosphate, the study proposes four new scenarios for improvement, including an integrated scenario where all the solutions are combined for a comprehensive approach. Both quantity and grade of recovered residual phosphate are assessed in each scenario. To evaluate these enhancements, the study utilizes the AnyLogic software to simulate existing process configuration and the maximal recovery of each scenario. The current flowsheet indicates that extracted phosphate can be directed either to pre-beneficiation and expedition or stored for future use. By prioritizing the extraction of phosphate over the final product, the simulation results suggest that implementing these novel scenarios could potentially save 25% of the total phosphate resource and increase storage by twofold, preserving phosphate that would otherwise be unused. This recovered phosphate can then be destined to various uses, meeting the company's present or future needs. Considering this, the study opts to keep stocks separated based on their grades and avoid mixing new phosphate streams with the final product. The implications of this research extend to sustainable mining practices, with direct ramifications for environmental impact mitigation and the conservation of valuable resources. • About 80% of phosphate rock is extracted from the deposit. • 42% of the current spoil piles, 75% of the current DPWR and 72% of the current SPWR is phosphate rock. • New flowsheets can recover and limit residual phosphate presence in the waste stocks. • Four new flowsheets were proposed and assessed using system dynamic simulation. • Production can be enhanced: the run-of-mine can increase by 32%. [ABSTRACT FROM AUTHOR]

Effective removal of phosphorus from water is crucial for controlling eutrophication. Meanwhile, the post-disposal of wetland plants is also an urgent problem that needs to be solved. In this study, seedpods of the common wetland plant lotus were used as a new raw material to prepare biochar, which were further modified by loading nano La(OH) 3 particles (LBC-La). The adsorption performance of the modified biochar for phosphate was evaluated through batch adsorption and column adsorption experiments. Adsorption performance of lotus seedpod biochar was significantly improved by La(OH) 3 modification, with adsorption equilibrium time shortened from 24 to 4 h and a theoretical maximum adsorption capacity increased from 19.43 to 52.23 mg/g. Moreover, LBC-La maintained a removal rate above 99% for phosphate solutions with concentrations below 20 mg/L. The LBC-La exhibited strong anti-interference ability in pH (3–9) and coexisting ion experiments, with the removal ratio remaining above 99%. The characterization analysis indicated that the main mechanism is the formation of monodentate or bidentate lanthanum phosphate complexes through inner sphere complexation. Electrostatic adsorption and ligand exchange are also the mechanisms of LBC-La adsorption of phosphate. In the dynamic adsorption experiment of simulated wastewater treatment plant effluent, the breakthrough point of the adsorption column was 1620 min, reaching exhaustion point at 6480 min, with a theoretical phosphorus saturation adsorption capacity of 6050 mg/kg. The process was well described by the Thomas and Yoon–Nelson models, which indicated that this is a surface adsorption process, without the internal participation of the adsorbent. [Display omitted] • A novel modified biochar was prepared from harvested wetland plant Lotus Seedpod. • LBC-La showed excellent phosphate adsorption performance. • Inner sphere complexation is the main adsorption mechanism. • The dynamic adsorption was well described by the Thomas and Yoon–Nelson models. [ABSTRACT FROM AUTHOR]

Using biowaste-based adsorbents to remove phosphorus (P) from wastewater offers significant benefits concerning eutrophication mitigation and addressing waste management challenges. In this work, Ca-biocomposites were prepared by pyrolysis (700 °C) of a mixture of banana peel (BP) and eggshell (ES). The mass ratio of BP to ES was varied in 2:1, 1:1, and 1:2 ratios. Among the tested mixtures, the BPES-1:2 sample exhibited excellent P removal performance, reaching a maximum P adsorption capacity (Qma x) of 214 ± 5 mg P/g. The adsorption process fitted well with the Avrami order kinetic model (R 2 > 0.996) and the Liu isotherms model (R 2 > 0.997). The excellent fit of the experimental data to the Avrami model suggests that chemisorption is the dominant interaction mechanism, leading to precipitation through the formation of calcium phosphates. Additionally, the Liu model anticipates that the energetic characteristics of the adsorbent's active sites cannot be identical. This is in agreement with the presence of Ca(OH) 2 and CaCO 3 in the adsorbent material, where the Ca(OH) 2 active sites are preferred by the adsorbate molecules (PO 4 3−) for occupation. Furthermore, thermodynamic analysis revealed that P adsorption is a spontaneous process of exothermic nature (ΔH° < 0). The calculated activation energy for the process (72.81 kJ/mol) suggests the P adsorption mechanism involves strong chemical bonding between the adsorbent and P species. In addition, precipitation of apatite (Ca 5 (PO 4) 3 OH), a vital component in fertilizer production, was observed during the adsorption process. In tertiary treated wastewater applications, the BPES-1:2 biocomposite demonstrated a P removal efficiency of 90%. The solubility of P in a 2% formic acid solution was 100%, while the water-soluble P content was measured at 5.6%. These findings highlight the product's sustainable and environmentally beneficial nature by demonstrating its potential as a slow-release fertilizer, contributing to the application of the 3R slogan: Reduce, Reuse, Recycle. This value-added product is promising in supplying nutrients to plants over an extended period while minimizing the risk of nutrients leaching into the environment. [Display omitted] • Eggshells and banana peels were used for Ca-biocomposites production. • Ca-biocomposite demonstrated an efficiency of 90% P removal from wastewater. • The presence of Ca(OH) 2 and CaO in the Ca-biocomposites improves the P removal. • Apatite is the main product after P removal. • The production cost of 1 kg of Ca-biocomposite is $ 6.4. [ABSTRACT FROM AUTHOR]

Phosphorus (P) removal from urban wastewater is increasingly relevant in the wastewater treatment sector. The present work aims to contribute to the study of the adsorption process as a P removal technology. Biogenic calcium carbonate from industrial eggshell waste prepared by milling and calcination was used as an adsorbent. Batch adsorption experiments were conducted using real wastewater with 40 mg P/L (orthophosphate), original pH 7.33, under stirring conditions (100 rpm). The adsorbent was characterized using SEM-EDS, XRD, and FTIR-ATR before and after adsorption. From an initial screening of calcination times (15, 30, 60, and 120 min) and considering a balance between P removal and energy saving, the adsorbent selected was eggshell calcined at 700 °C for 60 min. The Langmuir isotherms describe the experimental data with a maximum adsorption capacity of 4.57 mg P/g at 25 °C. The adsorption process reached equilibrium within 120 min for different dosages (5, 10, and 20 g/L at 25 °C). Batch experiments showed that SO 4 2−, at a concentration of 2689 mg/L reduced the P adsorption selectivity for dosages ≤10 g/L at 25 °C. Characterization of the loaded adsorbent shows that P adsorption from real wastewater is mostly electrostatic attraction, with the contribution of ligand exchange and microprecipitation. The adsorption capacity and behavior of the selected adsorbent seem promising for P removal from urban wastewater compared with other low-cost adsorbents. • Biogenic calcium carbonate-based adsorbent has potential for P removal. • The adsorbent showed good performance in real wastewater (4. 57 mg P/g). • Sulfate ions may influence the selectivity of the adsorbent for phosphorus. • The main mechanism for P removal in real wastewater is electrostatic attraction. [ABSTRACT FROM AUTHOR]

Abstract The requirement to the phosphorus (P) emission from wastewater treatment plants (WWTPs) is becoming increasingly strict, which makes an advanced treatment for the low-concentration phosphate removal from secondary effluents indispensable. In present work, hydrated lanthanum (La) oxide-modified diatomite composites (La-diatomite) were fabricated by a facile method and employed as the highly efficient adsorbent for the low-concentration phosphate removal from simulating secondary effluents. Comparative experiments indicated that the La-diatomite treated by 0.1 mol/L LaCl 3 exhibited the highest La availability (P/La molar ratio of 2.30) and performed good selectivity to phosphate adsorption even with the coexistence of competing anions and humic acid. The maximum P adsorption capacity reached to 58.7 mg P/g and the 96% P was removed quickly within 30 min at initial phosphate concentration 2 mg P/L. Insignificant La leaching was observed during the process due to the La stabilization by macroporous diatomite. Eight cycles of adsorption-desorption experiments revealed that the excellent repeated use property of La-diatomite. At the column test, La-diatomite showed superior treatment capacities of 3455 kg water/kg La-diatomite for simulated secondary effluents. The La-diatomite maintained high and stable adsorption effectiveness in wide pH range, which should be attributed to the synergistic effect of electrostatic interactions, ligand exchange and Lewis acid-based interaction. This work might provide a candidate for low-concentration phosphate removal from secondary effluent to alleviate the eutrophication. Graphical abstract Image 1 Highlights • La-diatomite possessed a high removal efficiency to low-concentration phosphate. • La-diatomite exhibited the maximum adsorption capacity of 58.7 mg P/g. • Phosphate adsorption was a pH-independent process. • La-diatomite showed superior treatment capacity for simulated secondary effluents. • The underlying adsorption mechanisms were elucidated in detail. [ABSTRACT FROM AUTHOR]

Treating wastewater using purple non-sulfur bacteria (PNSB) is an environmentally friendly technique that can simultaneously remove pollutants and lead to the accumulation of high-value cell inclusions. However, no PNSB system for treating heavy oil refinery wastewater (HORW) and recovering high-value cell inclusions has yet been developed. In this study, five batch PNSB systems dominated by Rhodopseudomonas were used to treat real HORW for 186 d. The effects of using different hydraulic retention times (HRT), sludge retention times (SRT), trace element solutions, phosphate loads, and influent loads were investigated, and the bacteriochlorophyll, carotenoid, and coenzyme Q 10 concentrations were determined. The community structure and quantity of Rhodopseudomonas in the systems were determined using a high-sequencing technique and quantitative polymerase chain reaction technique. The long-term results indicated that phosphate was the limiting factor for treating HORW in the PNSB reactor. The soluble chemical oxygen demand (SCOD) removal rates were 67.03% and 85.26% without and with phosphate added, respectively, and the NH 4 +-N removal rates were 32.18% and 89.22%, respectively. The NO 3 −-N concentration in the effluent was stable at 0–3 mg/L with or without phosphate added. Adding phosphate increased the Rhodopseudomonas relative abundance and number by 13.21% and 41.61%, respectively, to 57.35% and 8.52 × 106 gene copies/μL, respectively. The SRT was the limiting factor for SCOD removal, and the bacteria concentration was the limiting factor for nitrogen removal. Once the inflow load had been increased, the total nitrogen (TN) removal rate increased as the HRT increased. Maximum TN removal rates of 64.46%, 68.06%, 73.89%, 82.15%, and 89.73% were found at HRT of 7, 10, 13, 16, and 19 d, respectively. The highest bacteriochlorophyll, carotenoid, and coenzyme Q 10 concentrations were 2.92, 4.99, and 4.53 mg/L, respectively. This study provided a simple and efficient method for treating HORW and reutilizing resources, providing theoretical support and parameter guidance for the application of Rhodopseudomonas in treating HORW. • PNSB system with Rhodopseudomonas can treat heavy oil refinery wastewater effectively. • Phosphate improved SCOD and TN removal by 26.50% and 166.95% respectively in systems. • Phosphate obviously stimulated the growth of Rhodopseudomonas in PNSB system. • Rhodopseudomonas can adapt to higher concentrations of influent loads. • Compared to SCOD, nitrogen removal relied on longer HRT and higher bacterial concentration. [ABSTRACT FROM AUTHOR]

Livestock wastewater can contain high levels of phosphates and trace amounts of various ionic species harming the environment and human health. These ions can be successfully removed from livestock effluent and recovered in a non-toxic crystal form via crystallization. The fluidized bed homogeneous crystallization (FBHC) technology is a cutting-edge pretreatment method that removes phosphate and ammonium by crystallizing struvite. The findings demonstrated a 37% removal for ammonium solutions alone, 38% with copper, 35% with zinc, and 33% when copper and zinc were present, while the crystallization efficiency was achieved at 35%, 33% with copper, 28% with zinc, and 26% with copper and zinc. For phosphate-containing solutions, 95% was removed, 81% with copper, 96% with zinc, and 88% with copper and zinc. Similarly, crystallization efficiency was attained at 87%, 60% with copper, 94% with zinc, and 81% when copper and zinc were combined with phosphates. For ammonium solutions, copper and zinc reduced the removal and crystallization efficiency at constant pH and increased at increasing pH. For phosphate solutions, the removal and crystallization efficiencies increased at increasing pH. However, zinc ions resulted in the highest removal, and crystallization efficiency for phosphate solutions was attained. Based on SEM, EDS, XRD, and XPS analyses, the peaks revealed the presence of struvite in the form of magnesium ammonium phosphate. [Display omitted] • Struvite crystal was recovered as ammonium and phosphate at 94% in the presence of zinc ions. • The best pH of 9.0 of the effluent affected the ammonium and phosphate removal and crystallization. • The removal was best for phosphate ions in the presence of zinc at 95% and 94% for the crystallization. [ABSTRACT FROM AUTHOR]

Excessive existences of nutrients such as phosphate in the aqueous environment remain as a heavy concern although many researches have been reported for dealing with their removal. Based on the understanding toward the interactions of Fe compounds with phosphate and carbonate from many available researches, we designed a very simple and efficient approach for phosphate removal by using in situ generated fresh trivalent Fe composition through the interaction of Fe(II) as FeSO 4 on CaCO 3 . Addition and agitation of Fe(II) and CaCO 3 simultaneously to phosphate solution allowed an amorphous Fe(III)-P or Ca-Fe(III)-P precipitation, with a phosphate removal rate close to 100%, to reduce the residual phosphorus concentration less than 0.03 mg/L from 100 mg/L, reaching the discharge limit, even with the addition amounts of CaCO 3 as low as a stoichiometric ratio of CaCO 3 /PO 4 3− at 0.9 and ratio of Fe(II)/PO 4 3− at 1.5, and the percent of P 2 O 5 in the precipitate was as high as 19.4% enough as phosphate source for fertilizer production. Different from the alkaline process with enough OH − group, the slow hydrolysis of CaCO 3 resulting in low concentration of OH − group for the formation of Fe(OH) 2 , which was oxidized soon by air into trivalent Fe, achieved a continuous generation of fresh ferric composition for phosphate precipitation and could avoid its rapid formation and subsequent transformation into stable FeOOH of large particle size to lose the activity. These results based on the synergistic effect of using CaCO 3 and Fe(II) together may have applications in the treatment of eutrophic wastewater through a process with many advantages of easy operation and low-cost besides the high removal efficiency with phosphate percentage inside the precipitate high enough to serve for fertilizer production. [ABSTRACT FROM AUTHOR]

In this study, the feasibility of Mg/Al layered double hydroxides (LDH) functionalized coffee ground waste biochars (LDH MgAl @CWGB) as a potential adsorbent to selectively recover phosphate (PO 4 3−) and nitrate (NO 3 −) ions in aqueous phases and their consecutive uses as a slow-release fertilizer for stimulating the plant growth were identified. The higher adsorption capacity of PO 4 3− and NO 3 − ions by LDH MgAl @CWGB (PO 4 3− = 6.98 mgP/g, NO 3 − = 2.82 mgN/g) compared with pristine coffee ground waste biochars (CWGB; PO 4 3− = 0.19 mgP/g, NO 3 − = 0.32 mgN/g) was mainly due to the incorporation of Mg/Al mixed oxides and Cl contents. Chemisorption and intra-particle mainly controlled the adsorptive recovery of PO 4 3− and NO 3 − ions by CWGB and LDH MgAl @CWGB in aqueous phases and their adsorption toward CWGB and LDH MgAl @CWGB proceeded endothermically and spontaneously. The changes in the major adsorption mechanisms of PO 4 3− and NO 3 − ions from ligand exchange (CWGB) to electrostatic surface complexation and anion-exchange (LDH MgAl @CWGB) supported the conclusion that the alternation of the surface features through Mg/Al LDH functionalization might improve selectivity and adsorption capacity of PO 4 3− and NO 3 − ions onto CWGB under the co-existence of Cl−, SO 4 2−, and HCO 3 − ions. Since PO 4 3-- and NO 3 −-loaded LDH MgAl @CWGB exhibited much higher seed germination, root and shoot growth rates of garden cress seeds (Lepidium sativum L) than other liquid and solid matrices, including 5 mgP/L PO 4 3− and 5 mgN/L NO 3 −, 10 mgP/L PO 4 3− and 10 mgN/L NO 3 −, and LDH MgAl @CWGB, it can be postulated that PO 4 3-- and NO 3 −-loaded LDH MgAl @CWGB could be practically applicable to the agricultural field as a slow-release fertilizer to facilitate the seed germination, root and shoot growth of the plants. [Display omitted] • LDH MgAl @CWGB more efficiently captured PO 4 3− and NO 3 − ions than CWGB. • LE played a critical role in adsorption of PO 4 3− and NO 3 − ions onto CWGB. • Mg/Al LDH functionalization increased selectivity of CWGB for PO 4 3− and NO 3 − ions. • ESC and AE mainly governed adsorption of PO 4 3− and NO 3 − ions toward LDH MgAl @CWGB. • PO 4 3-- and NO 3 −-loaded LDH MgAl @CWGB promoted seed germination and plant growth. [ABSTRACT FROM AUTHOR]

Freshwater resources are vital for human and natural systems. However, anthropogenic activities, such as agricultural practices, have led to the degradation of the quality of these limited resources through pollutant loading. Agricultural Best Management Practices (BMPs), such as wetlands, are recommended as a valuable solution for pollutant removal. However, evaluation of their long-term impacts is difficult and requires modeling since performing in-situ monitoring is expensive and not feasible at the watershed scale. In this study, the impact of natural wetland implementation on total phosphorus reduction was evaluated both at the subwatershed and watershed levels. The study area is the Saginaw River Watershed, which is largest watershed in Michigan. The phosphorus reduction performances of four different wetland sizes (2, 4, 6, and 8 ha) were evaluated within this study area by implementing one wetland at a time in areas identified to have the highest potential for wetland restoration. The subwatershed level phosphorus loads were obtained from a calibrated Soil and Water Assessment Tool (SWAT) model. These loads were then incorporated into a wetland model (System for Urban Stormwater Treatment and Analysis IntegratioN-SUSTAIN) to evaluate phosphorus reduction at the subwatershed level and then the SWAT model was again used to route phosphorus transport to the watershed outlet. Statistical analyses were performed to evaluate the spatial impact of wetland size and placement on phosphorus reduction. Overall, the performance of 2 ha wetlands in total phosphorus reduction was significantly lower than the larger sizes at both the subwatershed and watershed levels. Regarding wetland implementation sites, wetlands located in headwaters and downstream had significantly higher phosphorus reduction than the ones located in the middle of the watershed. More specifically, wetlands implemented at distances ranging from 200 to 250 km and 50–100 km from the outlet had the highest impact on phosphorus reduction at the subwatershed and watershed levels, respectively. A multi criteria decision making (MCDM) method named VIKOR was successfully executed to identify the most suitable wetland size and location for each subwatershed considering the phosphorus reduction and economic cost associated with wetland implementation. The methods introduced in this study can be easily applied to other watersheds for selection and placement of wetlands while considering environmental benefits and economic costs. [ABSTRACT FROM AUTHOR]

Despite various research works on algal-bacterial aerobic granular sludge for wastewater treatment and resource recovery processes, limited information is available on its application in real wastewater treatment in terms of performance, microbial community variation and resource recovery. This study investigated the performance of algal-bacterial aerobic granular sludge on real low-strength wastewater treatment in addition to the characterization of microbial community and fatty acid compositions for biodiesel production. The results demonstrated 71% COD, 77% NH 4 +-N and 31% phosphate removal efficiencies, respectively. In addition, all the water parameters successfully met the effluent standard A, imposed by the Department of Environment (DOE) Malaysia. Core microbiome analyses revealed important microbial groups (i.e., Haliangium ochraceum , Burkholderiales and Chitinophagaceae) in bacterial community. Meanwhile the photosynthetic microorganisms, such as Oxyphotobacteria and Trebouxiophyceae dominated the algal-bacterial aerobic granular sludge, suggesting their important roles in granulation and wastewater treatment. Up to 12.51 mg/gSS lipid content was recovered from the granules. In addition, fatty acids composition showed high percetages of C16:0 and C18:0, demonstrating high feasibility to be used for biodiesel production application indicated by the cetane number, iodine value and oxidation stability properties. [Display omitted] • First report on microbial community and lipid recoveries during treatment of real wastewater. • COD (47 mg/L), ammoniacal nitrogen (3.9 mg/L) and phosphate (2 mg/L) discharge within standards by local authorities. • Haliangium ochraceum , Burkholderiales and Chitinophagaceae as the core bacterial microbiome. • Dominance of Oxyphotobacteria and Trebouxiophyceae as photosynthetic microorganisms. • 12.51 mg/gSS lipid recoveries with dominance of C16:0 (38%) and C18:0 (25%). [ABSTRACT FROM AUTHOR]

Large volumes of iron-containing sludge (Fe-Sludge) would be generated with the application of iron salts in drinking water treatment plants, which must be disposed appropriately. One of the common disposal solutions for Fe-Sludge is through direct disposal into the municipal sewer system, whereby it would be mixed with domestic wastewater and treated in the wastewater treatment plant. To better understand the properties of Fe-Sludge and the effect of dosing Fe-Sludge to the real domestic wastewater (WW) on the wastewater characteristics, a serial batch tests were conducted on a local wastewater reclamation plant (WRP). It was found that the impact of dosing Fe-Sludge at a Fe/P ratio of 5 did not vary with the types of WW, i.e., filtered or non-filtered by the 5 mm screen. In addition, the soluble organic, phosphate and total soluble iron concentrations mostly decreased with the dosing of Fe-Sludge within the dosage range of 0–5 (Fe/P ratio). In contrast, the suspended solid (SS) and volatile suspended solid (VSS) concentrations increased with the dosage of Fe-Sludge within the dosage range of 0–5 (Fe/P ratio). Furthermore, the pH condition of the domestic wastewater affected the phosphate removal efficiency by Fe-Sludge and influenced the total soluble iron concentration and iron species distribution. These findings will provide fundamental support for the further study of the effect of Fe-Sludge on the biological treatment performance and membrane filtration performance of the membrane bioreactor (MBR) system. • Fe-Sludge generated from waterworks containing high iron (∼0.32 g Fe/g Fe-Sludge). • SCOD, P and total soluble iron of WW mostly decreased with Fe-Sludge dosing. • P removal efficiency with Fe-Sludge dosing varied with pH condition of WW. • Effect of Fe-Sludge dosing on characteristics of AS-WW and BS-WW were comparable. [ABSTRACT FROM AUTHOR]

Shrimp farming wastewater includes high amounts of phosphate and microbiological contaminants, necessitating further treatment before release into receiving water bodies. After 24 h of shrimp wastewater treatment, alginate beads containing the blue-green algal Synechocystis strain lacking the phosphate regulator gene (mutant strain ΔSphU) at 150 mg L−1 reduced phosphate content from 17.5 mg L−1 to 5.0 mg L−1, representing 71.5% removal efficiency, with phosphate removal rate reaching 6.9 mg gDW−1 h−1 during photobioreactor operation. For short-term treatment, removal rates of nitrate, ammonium and nitrite were 42.7, 48.5 and 92.9%, respectively. Microalgal encapsulated beads also impacted the bacterial community composition dynamics in shrimp wastewater. Next-generation sequencing targeting the V3–V4 region of the 16S rDNA gene showed significant differences in bacterial community composition after 24 h of treatment. Proteobacteria are the most abundant phylum in shrimp wastewater. After 24 h of bioremediation, reductions of harmful bacteria in the Cellvibrionaceae and Pseudomonadaceae families were recorded at 5.85 and 3.18%, respectively. Engineered microalgal immobilization under optimal conditions can be applied as an alternative short-term bioremediation strategy to remove phosphate and other harmful microbial contamination from shrimp farming wastewater. [Display omitted] • Shrimp wastewater treatment using immobilized engineered microalgae in photoreactor. • Alginate immobilized microalgae could remove phosphate reached 6.9 mggDW−1h−1. • The 12.5 mg L−1 of phosphate-containing wastewater was removed within 24 h. • Immobilized microalgae impacted on bacterial community in shrimp wastewater. • The microbiota of pathogenic bacteria was significantly decreased during treatment. [ABSTRACT FROM AUTHOR]

The effect of temperature on the efficiency of organics and nutrients removal during the cultivation of aerobic granular sludge (AGS) in biological treatment of synthetic wastewater was studied. With this aim, three 3 L sequencing batch reactors (SBRs) with influent loading rate of 1.6 COD g (L d) −1 were operated at different high temperatures (30, 40 and 50 °C) for simultaneous COD, phosphate and ammonia removal at a complete cycle time of 3 h. The systems were successfully started up and progressed to steady state at different cultivation periods. The statistical comparison of COD, phosphate and ammonia for effluent from the three SBRs revealed that there was a significant difference between groups of all the working temperatures of the bioreactors. The AGS cultivated at different high temperatures also positively correlated with the accumulation of elements including carbon, oxygen, phosphorus, silicon, iron, aluminium, calcium and magnesium that played important roles in the granulation process. [ABSTRACT FROM AUTHOR]

Combination of high performance membrane bioreactor (MBR) equipped with ultrafiltration and electro-oxidation process (EOP) by boron-doped diamond electrode (BDD) was used to effectively treat highly contaminated old landfill leachate. MBR and EOP were optimized for raw and pretreated landfill leachate. Seasonal changes dramatically affected the both processes' performance, as the landfill leachate was ¾ more concentrated in winter. For MBR, organic load rate of 1.2 gCOD/L/day and sludge retention time of 80 days was considered as the optimum operating condition in which COD, TOC, NH 4 + and phosphorous removal efficiencies reached the average of 63, 35, 98 and 52%, respectively. The best performance of EOP was in current intensity of 3 A with treatment of time of 120 min. Effluent of electro-oxidation was more toxic due to the presence of radicals and organochlorinated compounds. These compounds were removed by stripping or assimilation of sludge if EOP was used as a pretreatment method. Furthermore, the energy consumption of EOP was decreased from 22 to 16 KWh/m 3 for biologically treated and raw landfill leachate, respectively. [ABSTRACT FROM AUTHOR]

The microalgal species Chlorella vulgaris was cultivated in batch conditions to identify the optimum set of initial conditions for the best biomass growth rate, phosphate removal, polyphosphate accumulation, and protein productivity. To study the effect of phosphorus deficiency caused stress, the microalgal biomass was exposed to phosphorus deficiency conditions for periods varying between 1 and 10 days and inoculated at different initial biomass and phosphate concentrations. A 10-day period of phosphate deficiency, supported by low initial biomass concentration (∼0.25 mg DW L−1), increased the phosphate removal by 62–175% when compared to the reference conditions. A 10-day period of biomass P-deficiency also boosted the polyphosphate accumulation and protein productivity, increasing them up to 40 and 46.8 times, respectively, if compared to reference conditions. At the same time, optimization algorithm model results suggested one-day biomass P-starvation with low initial biomass concentration as the optimum combination to achieve the highest performance while the initial phosphate concentration had less impact. The initial conditions suggested by the optimization model were validated in a sequencing batch photobioreactor, giving 101.7 and 138.0% more phosphate removal and polyphosphate accumulation, compared to the reference conditions. The obtained results present microalgae exposure to phosphorus stress as a supplementary tool for wastewater post-treatment targeted on rapid phosphorus removal. • Chlorella vulgaris exposure to a condition of phosphorus (P) deficiency induced biomass P-starvation. • P-starvation enhanced the phosphate uptake from synthetic wastewater by C. vulgaris. • Polyphosphate accumulation and protein productivity increased for P-starved biomass. • P-starvation and low biomass density in photobioreactor boosted the wastewater bioremediation. • Biomass P-starvation showed potential for improved wastewater post-treatment. [ABSTRACT FROM AUTHOR]

This multiscale model quantifies transport and reaction processes in mixotrophic microalgal growth at three characteristic length scales, namely, macro (photobioreactor), meso (algal cell), micro (organelles). The macro and the meso scale equations capture the temporal dynamics of the transport of CO 2 , O 2 , H+, organic carbon and nitrogen sources in the photobioreactor and the cell, respectively, while the micro scale quantifies the reaction rates of CO 2 fixation and photorespiration in the chloroplast, and mitochondrial respiration. Our model is validated using our experiments (R 2 = 0.96-0.99) on urea, CO 2 (0.04–5%), and acetic acid-mediated mixotrophic cultivation of Chlorella sorokiniana for 138 h using municipal wastewater (with and without media) at 11,000 lx light in 25-liter pilot-scale bubble-column photobioreactors, which produces 0.47–2.74 g/L biomass with 22.8–29.6% lipids, while reducing the COD, ammonium, phosphate, nickel, and H+ concentrations by 65–89%. The alga assimilates the ammonium and the phosphates present in wastewater into amino acids and ATP, respectively. Our simulations quantify the autotrophic and heterotrophic components of mixotrophic biomass yield to find the optimal inlet CO 2 concentration (of 3%) that synergizes autotrophic CO 2 sequestration with heterotrophic assimilation of organic carbon, thereby maximizing both autotrophic and heterotrophic growths. Super-optimal levels of inlet CO 2 acidify the stroma of the chloroplast, inhibit RuBisCo's enzymatic activity for CO 2 fixation in the Calvin Cycle, decelerate carrier-mediated uptake of acetate, and reduce biomass yields. Our harvesting process drastically reduces the algal harvesting time to less than 29 min. This multiscale reaction-transport model provides a useful tool for further scaling up this pilot-scale technology that synergistically integrates CO 2 sequestration and wastewater treatment with rapid microalgal cultivation (using municipal wastewater without autoclaving) and cost-effective harvesting. [ABSTRACT FROM AUTHOR]

Effective and efficient disposal of radioactive pollution has been crucial for responding to unexpected nuclear accidents and guaranteeing the sustainable development of nuclear energy. In this study, a kind of porous zirconium phosphate was synthesized with a sol–gel process followed by a post-synthesis modification to remove the radioactive Sr2+ from wastewater. The prepared materials were characterized by different technologies including FT-IR, SEM-EDS, XRD and XPS, and then the adsorption performance was evaluated in batch and column modes. Experimental results suggested that the porous zirconium phosphate adsorbent was successfully prepared with Na+ dispersed in the channels for exchange. It inherited the excellent properties of zirconium dioxide aerogel and exhibited mesoporous structure and large specific surface area. Compared with traditional zirconium phosphate, the adsorption kinetics and the adsorption capacity were improved simultaneously. Especially, it showed excellent selectivity towards Sr2+ among different cations, and even could remove the low-level Sr2+ from natural seawater efficiently, which powerfully demonstrated that the prepared material could be applied in the treatment of practical wastewater. Spectra studies uncovered that the adsorption activities were dominated by the ion exchange mechanism between external Sr2+ and interlaminar Na+ or H+. In conclusion, this paper not only reports a novel synthesis strategy for the acquisition of porous zirconium phosphate, but also presents a promising adsorbent for the Sr2+ removal. [Display omitted] • A kind of porous zirconium phosphate material was prepared as Sr2+ adsorbent. • The adsorption behavior was studied in the batch and column experiments. • The adsorption capacity and kinetics were improved. • Natural seawater was used to verify the practical removal performance for Sr2+. • Adsorption mechanism was confirmed by SEM-EDS, XRD, and XPS spectroscopy. [ABSTRACT FROM AUTHOR]

This study examined the impact of chemical oxygen demand (COD) loading and dissolved oxygen (DO) concentration on the stability and performance of granular sludge treating high saline municipal sewage. Under high DO concentrations of 4.0–7.0 mg/L, and COD loading rates of 0.98 and 1.55 kg/m 3 /d, rapid settling granules were established within four weeks of start-up. Under the highest COD load, a reduction in DO lead to the rapid deterioration of the sludge volume index (SVI) and washout of granules due to prolific growth of the filament Thiothrix Type 021N. Conversely, when operated under a lower COD load, a reduction in DO concentration had no adverse impact on the stability of SVI and granules. A decrease in DO also improved nitrogen removal performance, where simultaneous removal of ammonium (98%), total nitrogen (86%) and BOD 5 (98%) were achieved when median DO concentrations were between 1.0 and 1.5 mg/L. Phosphate removal was lower than expected, however the level of biological phosphate removal activity observed appeared sufficient to maintain granule stability, even under low DO concentrations. Nitrous oxide emissions were also characterised, which ranged between 2.3 and 6.8% of the total nitrogen load. Our results confirmed that granular sludge is a viable option for the treatment of saline sewage. [ABSTRACT FROM AUTHOR]

It is difficult to eliminate phosphate from large volumes of water in batch mode using an adsorbent such as andosol. In a fixed-bed column, andosol has a very low permeability. In this study, andosol was mixed with bagasse to increase permeability. The mixture was then applied for the adsorption of phosphate in a fixed-bed column. Optimum and stable permeability was obtained with a 50/50 mixture of andosol and bagasse. The maximum adsorption capacity obtained was 4.18 mg/g for a column with a bed depth of 1.8 cm and a flow rate of 4 mL/min. The experimental data fit best to Thomas and Adam–Bohart models. These experimental results were applied in the treatment of natural phosphate-containing water from Yaoundé Municipal Lake in Cameroon. Column performance increased by 60% due to the presence of Ca 2+ and Mg 2+ in the natural water. These cations form complexes with phosphate at the andosol surface. The standard enthalpy 15.964 kj/mol indicated that phosphate adsorption on andosol-bagasse mixture was an endothermic process. Kinetic experiments demonstrated that phosphate adsorption fitted better with a pseudo-second-order model. [ABSTRACT FROM AUTHOR]

This work studies the use of a well-known and spread activated sludge system (UCT configuration) to treat the effluent of a submerged anaerobic membrane bioreactor (SAnMBR) treating domestic wastewater. Ammonia, phosphate, dissolved methane and sulphide concentrations in the SAnMBR effluent were around 55 mg NH4–N L−1, 7 mg PO4 –P L−1, 30 mg non-methane biodegradable COD L−1, and 105 mg S 2− L−1 respectively. The results showed a nitrification inhibition caused by the presence of sulphur compounds at any of the solids retention time (SRT) studied (15, 20 and 25 days). This inhibition could be overcome increasing the hydraulic retention time (HRT) from 13 to 26 h. Among the sulphur compounds, sulphide was identified as the substance which caused the nitrification inhibition. When the nitrification was well established, removal rates of nitrogen and phosphorus of 56% and 45% were reached respectively. The sulphide present in the influent was completely oxidised to sulphate, contributing this oxidation to the denitrification process. Moreover, the presence of methanotrophic bacteria, detected by FISH technique, could also contribute to the denitrification. [ABSTRACT FROM AUTHOR]

The valorisation of wastewaters for minerals recovery and their potential beneficiation has gained enormous attention recently. In this study the removal of phosphate and ammonia from municipal wastewater using activated magnesite resulted in the formation of struvite. The optimum conditions for the synthesis of struvite were 60 min of mixing, 300 rpm mixing speed, 1 g of activated magnesite and room temperature, whilst optimum conditions for the treatment of acid mine drainage (AMD) using the synthesized struvite were 45 min of mixing, 20 g of struvite dosage, 1000 mL, and 300 rpm mixing speed. The efficacy of struvite for neutralisation of AMD and attenuation of inorganic contaminants were ≥98.99% for metals (Al3+, Fe3+, and Mn2+) and ≥30% for SO 4 2 − . Traces of other metals such as Zn, Cu, Ni, Pb, and Cr were significantly attenuated. Phosphate was fully attenuated from the aqua-sphere. PHREEQC predicted the removal of minerals as oxy-(hydro)-sulphates, oxy-(hydro)-phosphate, metals hydroxides, and other complexes. FE-SEM equipped with FIB and an EDX, XRD, XRF, and FTIR confirmed the synthesis of struvite and fate of chemical species after treatment. This study confirmed the feasibility of recovering phosphate and ammonia as struvite which can be employed for the treatment of AMD. • Activated cryptocrystalline magnesite- MWW interaction formed high grade struvite. •Struvite neutralized AMD and removed more than 90% of metals in solution. •Minerals removal as oxy-(hydro)-sulphates, oxy-(hydro)-phosphate and hydroxides. •MWW can be treated and valorized by recovering phosphate and ammonia as struvite. •Effective application of struvite for AMD treatment ensures circular economy. [ABSTRACT FROM AUTHOR]

Abstract: Domestic wastewater is a source of phosphorus contamination that causes eutrophication when it contaminates aquatic environments. Nelumbo nucifera Gaertn. and Cyperus alternifolius L. were applied for phosphorus removal from domestic wastewater. From the study, phosphorus in domestic wastewater was removed from the initial concentration of 1.038 ± 0.001 mgL−1 to 0.094 ± 0.001 and 0.048 ± 0.004 mgL−1 by N. nucifera and C. alternifolius, respectively, within 5 days. In addition, total Kjeldahl nitrogen (TKN) and chemical oxygen demand (COD) also decreased when wetland systems were applied the same as treatment with conventional method (chemical + activated sludge process). However, the plant removed TDS better than the conventional method. During 5 cycles of exposure, the two plants still survived and were healthy. The weight of plants increased after the experiment from 4060 ± 0.05 g to 4820 ± 0.17 g of N. nucifera, and from 4000 ± 0.00 g to 4600 ± 0.14 g of C. alternifolius. Phosphorus content also increased in both plants after the experiment. However, in the wetland system, phosphorus was removed mainly by the soil, followed by the plants, and then microorganisms. The domain group in the microbial community of both wetland systems was Pseudomas sp. [Copyright &y& Elsevier]

Greywater flows and concentrations vary greatly, thus evaluation and prediction of the response of on-site treatment filters to variable loading regimes is challenging. The performance of 0.6 m × 0.2 m (height × diameter) filters of bark, activated charcoal and sand in reduction of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total nitrogen (Tot-N) and total phosphorus (Tot-P) under variable loading regimes was investigated and modelled. During seven runs, the filters were fed with synthetic greywater at hydraulic loading rates (HLR) of 32–128 L m−2 day−1 and organic loading rates (OLR) of 13–76 g BOD5 m−2 day−1. Based on the changes in HLR and OLR, the reduction in pollutants was modelled using multiple linear regression. The models showed that increasing the HLR from 32 to 128 L m−2 day−1 decreased COD reduction in the bark filters from 74 to 40%, but increased COD reduction in the charcoal and sand filters from 76 to 90% and 65 to 83%, respectively. Moreover, the models showed that increasing the OLR from 13 to 76 g BOD5 m−2 day−1 enhanced the pollutant reduction in all filters except for Tot-P in the bark filters, which decreased slightly from 81 to 73%. Decreasing the HLR from 128 to 32 L m−2 day−1 enhanced the pollutant reduction in all filters, but decreasing the OLR from 76 to 14 g BOD5 m−2 day−1 detached biofilm and decreased the Tot-N and Tot-P reduction in the bark and sand filters. Overall, the bark filters had the capacity to treat high OLR, while the charcoal filters had the capacity to treat high HLR and high OLR. Both bark and charcoal filters had higher capacity than sand filters in dealing with high and variable loads. Bark seems to be an attractive substitute for sand filters in settings short in water and its effluent would be valuable for irrigation, while charcoal filters should be an attractive alternative for settings both rich and short in water supply and when environmental eutrophication has to be considered. [Copyright &y& Elsevier]

Abstract: Synthetic goethite and thermally treated goethite at different temperatures were used to remove phosphate from sewage. The effect of annealing temperature on phosphate removal over time was investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption and desorption (BET), and infrared emission spectrum (FT-IES) were utilized to characterize the phase, morphology, specific surface area, pore distribution, and the surface groups of samples. The results show that annealed products of goethite at temperatures over 250°C are hematite with the similar morphology as the original goethite with different hydroxyl groups and surface area. Increasing temperature causes the decrease in hydroxyl groups, consequential increase in surface area at first and then experiences a decrease (14.8–110.4–12.6m2/g) and the subsequent formation of nanoscale pores. The variation rate of hydroxyl groups and surface area based on FT-IES and BET, respectively, are used to evaluate the effect of annealing temperature on phosphate removal. By using all of the characterization techniques, it is concluded that the changes of phosphate removal basically result from the total variation rate between hydroxyl groups and surface area. [Copyright &y& Elsevier]

Abstract: In the present study, a novel tablet porous material (TPM) was developed from Kanuma clay (K-clay), corn starch, and calcium oxide. Laboratory-scale batch experiments were conducted to evaluate the phosphate adsorption capacity of TPM from aqueous solution. The adsorption isotherms, adsorption kinetics, phosphate recycling, and major factors such as temperature, pH, and dosage were investigated. The phosphate adsorption results fitted the Freundlich isotherm model very well, and the adsorption process was an endothermic and spontaneous reaction which could be described by a pseudo second-order kinetic model. The maximum phosphate adsorption capacity was 4.39mgg−1, and its equilibrium could be attained in 2h. The solution pH had little effect on TPM phosphate removal when pH varied from 5.0 to 9.0. 70.29% of adsorbed phosphate could be recycled when 0.2N HCl was used as eluant, and the present developed TPM could be recovered and reused for 5 times. This novel developed TPM is a promising adsorbent than other clay mineral materials for phosphate removal from wastewater. [Copyright &y& Elsevier]

Phosphorus (P) inputs to sewage treatment works (STW) come from a variety of sources and filtration of treated wastewater prior to discharge into receiving waters is a common practice. This means P in treated wastewaters may be present in forms that are potentially more bioavailable and mobile. We conducted a 2-year study to determine P species up and downstream of two STW outfalls into two tributaries of the River Thames. Downstream of the outfalls, P concentrations in both rivers were frequently greater by an order of magnitude for all species of P. A high proportion of total P (TP) in the downstream waters was determined as dissolved, which was largely comprised of soluble reactive P (SRP) – considered as the most bioavailable P species. Furthermore no significant difference in SRP was found in receiving waters passed through 0.45 and 0.10 μm filters. This means that P from STWs occurs in <0.1 μm fraction size, which will not readily settle to the channel bed and is more easily assimilated by biota. This distinguishes STW inputs from agricultural runoff where a high proportion of P occurs as particulate P which is both less bioavailable and more likely to settle to the channel bed. This implies that STWs derived P is likely to have a greater adverse impact on the receiving river than agricultural runoff. [Copyright &y& Elsevier]

Abstract: Tetravalent Zr4+ ion incorporated ZnAl hydrotalcite-like material with varying Zn/(Al+Zr) atomic ratio (2–4) and Al/Zr atomic ratio 0.7:0.3 with as interlayer anion were successfully synthesized and characterized by various physicochemical methods. The phosphate uptake studies were carried out over these materials by batch method with the objective of enhancing the uptake through creation of higher positive charge on brucite-like layers by the incorporation of Zr4+. The studies revealed that ternary ZnAlZr hydrotalcites show good uptake capacity for phosphate, among which ZnAlZr4-HT depicts a maximum uptake of around 91mgP/g. We observed that phosphate uptake results in the formation of layered hopeite mineral (Zn3(PO4)3·4H2O) on the surface of material by the surface precipitation of dissolved zinc ion through the outer-sphere complex formation of phosphate. The phosphate uptake increases with a decrease in Zn/Al and Zn/(Al+Zr) atomic ratios. Effects of initial phosphate concentration, contact time, adsorbent amount and temperature variation on phosphate uptake were studied. Co-presence of competitive anion like nitrate enhances the uptake of phosphate to 148mgP/g. Recycle studies of the material shows a decrease in the uptake of phosphate with the number of cycles due to an increase in the crystallinity. Very high uptake of phosphate by these materials even in the presence of other anions/cations suggests their potential role in waste water remediation. [Copyright &y& Elsevier]

Improving the buffer capacity of the electrolyte can enhance the anode performance in bioelectrochemical systems (BESs). To elucidate the mechanism underlying the facilitated BESs performance, this study used three different anode biofilms cultured with different concentrations of phosphate buffer (5, 50 and 100 mM) to investigate the biofilm response, in terms of the spatial structure of metabolic activity and microbial community, to different buffer capacities. Results showed that the electrochemical activities of the anode biofilms positively correlated with the buffer concentration. The spatial stratification of metabolic activity and microbial community of the anode biofilms were regulated by the buffer capacity, and the spatial microbial heterogeneity of the anode biofilm decreased as the buffer concentration increased. With increasing buffer capacity, Geobacter spp. were enriched in both the inner and outer layers of the biofilm, and the inhibition of methanogens growth improved the COD removal attributed to anode respiration. Additionally, the stimulation of EPS production in biofilms played a role in increasing the electrochemical performance of biofilms by buffer improvement. This study first revealed the regulation of buffer capacity on the stratification of anode biofilm during brewery wastewater treatment, which provided a deep insight into the relation of biofilm structure to its electrochemical properties. • Investigated anode biofilms cultured with three different buffer concentrations. • Electroactivity of anode biofilm positively correlated with buffer concentration. • Buffer capacity regulated the spatial stratification of biofilm community. • High buffer stimulated Geobacter in the inner and outer layers of the biofilms. • High buffer increased EPS production in the biofilms benefit to current production. [ABSTRACT FROM AUTHOR]

Anodizing wastewater contains principally phosphate (PO 4 3−) anions according to previous studies, but with the purpose to promote water reuse in this type of industry, a complete characterization of wastewater was made to remove other anions and cations also present in significant concentration. Particularly, the adsorption of sodium (Na+), potassium (K+), fluoride (F−), sulfate (SO 4 2−) and phosphate (PO 4 3−) was studied using different sorbents such as: coconut shell activated carbon, bone char, bituminous coal activated carbon, natural zeolite, silica, anionic and cationic exchange resins, a coated manganese-calcium zeolite, coconut shell activated carbon containing iron and iron hydroxide. All sorbents were characterized using FT-IR spectroscopy, potentiometric titration, nitrogen adsorption isotherms at 77 K, X-ray diffraction and SEM/EDX analysis to study the adsorption mechanism. The adsorption studies were performed in batch systems under constant agitation using both standard solutions of each ion and real anodizing wastewater. Results showed that, in general, the adsorption of all anions and cations is higher when mono-component standard solutions were used, since in the anodizing wastewater all species are competing for the active sites of the adsorbent. Na+ present in anodizing wastewater was efficiently adsorbed on coated manganese-calcium zeolite (20.55 mg/g) and natural zeolite (18.55 mg/g); while K+ was poorly adsorbed on all sorbents (less than 0.20 mg/g). Anions such as F−, SO 4 2− and PO 4 3−, were better adsorbed on the anionic resin (0.17, 45.38 and 2.92 mg/g, respectively), the iron hydroxide (0.14, 7.96 and 2.87 mg/g, respectively) and the bone char (0.34, 8.71 and 0.27 mg/g, respectively). All these results suggest that adsorption is a promising tertiary treatment method to achieve water reuse in the anodizing industry. [Display omitted] • Anodizing wastewater contains principally phosphates, sulphates, and sodium ions. • Natural and modified zeolites efficiently remove sodium from anodizing wastewater. • The best anions adsorbents are iron hydroxide and materials with hydroxyapatite. • Adsorption mechanisms of anions are ion exchange and electrostatic interaction. [ABSTRACT FROM AUTHOR]

Climate change not only intensifies eutrophication and enhances the rainfall, but also elevates the contents of greenhouse gases, which can further increase the intensity and frequency of extreme precipitation events. The effectivity of phytoremediation of urban wastewaters by water hyacinths under an extreme rainfall event (up to 380 mm d−1) was investigated using self-designed fabrications with six flow rates (2–15 m3 d−1) in situ on pilot scale for 30 days. The results suggest that water hyacinths had high N and P removal capacities even under adverse conditions such as low dissolved oxygen concentrations (DO, <1 mg L−1) and high ammonium concentrations (NH 4 +-N, >7 mg L−1). Specifically, the highest removal yields of N and P were 13.14 ± 0.47 g N·m−2·d−1 and 2.12 ± 0.04 g P·m−2·d−1, respectively. The results indicate that water hyacinths can be used for water treatment to reduce the amounts of NH 4 +-N, dissolved organic nitrogen (DON) and phosphate (PO 4 3−) even during extreme precipitation events. Moreover, DO increased due to wet deposition, runoff and surface flows during the extreme rainfall event, resulting in shifts between nitrification and denitrification processes which significantly altered nitrogen forms in urban wastewater. Results of this study suggest that water hyacinths could be recommended as a cost-effective and eco-friendly technology for urban wastewater phytoremediation in areas suffering from frequent extreme precipitation events. Image 1 • Phytoremediation with water hyacinths proved to be effective. • DO increased after extreme precipitation. • Changes in DO resulted in shifts between nitrification and denitrification. • Up to 99% NH 4 +-N and DON were removed by water hyacinths. • Water hyacinths were also effective during extreme precipitation. [ABSTRACT FROM AUTHOR]

This study mainly focuses on the efficiency of anodic oxidation process (Ti/Sb-SnO 2 /PbO 2 as anode and stainless steel as the cathode) in treating two different streams of urban wastewater, one from the influent of sequence batch reactor (WW1) and other from the effluent of constructed wetland (WW2). The effect of different operational parameters such as current density, hydraulic retention time, exposed electrode surface area, phosphorous, ammonia-nitrogen, nitrates, and coliform bacteria was studied. For an optimized current density of 30 mA/cm2 and an electrode surface area of 30 cm2, almost complete removal of COD and ammonia-nitrogen were achieved with both wastewaters (WW1 & WW2), while in case of phosphorous, 50% and 98% removal efficiencies were observed. Electrode deposition was analyzed using SEM-EDS and XRD, which confirms the presence of calcium and magnesium phosphates on the surface on the anode, which attributes to the phosphate removal. Electrochemical disinfection studies showed that complete inactivation of bacteria takes place within 30 min for WW1 and 60 min for WW2, and the cell morphological changes were studied using SEM analysis. Degradation of different micropollutants present in the wastewaters was evaluated with the aid of GC-MS. ICP - MS analysis confirmed that there was no leaching of lead from the anode surface, and the lead which is already present in the wastewater gets reduced to a permissible level, which further increases the treatment efficiency. Hence cleaner and comprehensive treatment of real urban wastewaters through anodic oxidation process was successfully demonstrated in this work. Image 1 • One step comprehensive treatment of urban wastewaters by electrochemical oxidation. • ~99.9% COD, 98% phosphorous and 100% ammonia-nitrogen removal was achieved. • Phosphorous removal was by forming calcium and magnesium phosphates on the cathode. • Complete inactivation of coliforms within a short period with cell wall rupture. • 100% removal of certain emerging and micro pollutants was noted using GC-MS. [ABSTRACT FROM AUTHOR]

Eutrophication which caused by excessive phosphorus in aquatic environment is a worldwide problem. Phosphorus is a nonrenewable resource widely used in agriculture and industry. Therefore, the development of economical methods for phosphorus capture and reuse from wastewater is urgently needed. In this study, a novel granule chitosan inlaid with γ-AlOOH on its structure (γ-AlOOH@CS) was prepared for phosphate removal with a recycle manner. Results showed that γ-AlOOH@CS exhibited a fast phosphate removal of 0.5 h for half adsorption capacity. The material presented a high adsorption capacity of 45.82 mg/g, the adsorption capacity maintained stability at pH 4–6, and favorable selectivity was observed when compared with other common anions. Column experiment was also performed well in treatment of the simulated wastewater. Isotherms and thermodynamics studies indicated that phosphate adsorption onto γ-AlOOH@CS was heterogeneous, spontaneous and exothermic. In material recycle experiment, by using NaOH solution as solvent and phosphoric acid as precipitant under hydrothermal reaction conditions, the products of chitosan, aluminum phosphate and sodium dihydrogen phosphate were obtained, with their purity reaching the industrial standard. Meanwhile, chitosan can be reused for new γ-AlOOH@CS preparation. This study provides a total recycle strategy of phosphorus removal from wastewater. Image 1 • Granule adsorbent of boehmite inlaid in chitosan was prepared to recover P in wastewater. • γ-AlOOH@CS performed relatively fast adsorption rate, high capacity, and favorable selective in batch experiment. • γ-AlOOH@CS in fixed-bed columns also effectively removed P from the synthetic wastewaters with p concentrations of 2.31 mg/L. • The adsorbents were converted to useful materials by using a novel strategy, after adsorption. [ABSTRACT FROM AUTHOR]

Methods of removing phosphate from wastewater with a low phosphate concentration are of great environmental significance. In this study, immobilized beads were prepared by entrapping modified bentonite powder in calcium-alginate (Al-NaBT-CA), and the potential of the beads for phosphate removal from wastewater was investigated. The effects of pH (1–10) and initial phosphate concentration (0.5–50 mg/L) were also examined in batch experiments with Al-NaBT-CA beads. The optimum pH value for phosphate removal by Al-NaBT-CA beads was pH 3. In addition, a high initial phosphate concentration promoted phosphate adsorption. Adsorption kinetics showed that the adsorption of phosphate using beads followed a pseudo-second-order kinetic model (R 2 = 0.98–0.99). The adsorption isotherm data was well fitted by the Sips adsorption model. The maximum phosphate adsorption capacity of the Al-NaBT-CA beads was 15.77 mg/g, which was slightly less than that of the modified powder. The specific surface area of the Al-NaBT-CA beads was 17.01 m2/g, and their average pore size was 13.41 nm. Scanning electron microscopy suggested that the high inner porosity and rough outer surface of the beads facilitated phosphate transfer. Image 1 • Al-modified NaCl-activated bentonite was entrapped in Ca-alginate as an adsorbent. • The maximum adsorption capacity of phosphate was 15.77 mg/g for entrapped beads. • Entrapment modified bentonite in alginate beads can separate easily from wastewater. • Entrapment beads have an applicability for treating real phosphate wastewater. [ABSTRACT FROM AUTHOR]

Phosphate and nitrate enrichment largely impair aquatic ecosystem functions and services, thus comprising an emerging problem of environmental concern. The problem pertains to developing countries where their discharge to surface water is on the rise due to a rapid growth in population. Herein, these pollutants (phosphate and ammonia) were removed from real municipal wastewater using a simple, fast, and cost-effective process. Raw cryptocrystalline magnesite, a mineral abundant in South Africa, was simply milled and calcined (mechano-thermo processing) in order to produce the activated magnesite (feed). The feed was then used in batch processing for pollutants adsorption and precipitation from real wastewater. The process was optimised by varying the treatment or contact time, feed dosage, concentration, pH, and temperature. The feed and product mineral (produced sludge) were characterised using X-ray Diffraction (XRD), field emission scanning electron microscopy (FESEM) compatible with energy dispersive spectroscopy (EDS), and Fourier Transform Infrared Spectrometer (FTIR). It was identified that the optimal conditions differed for each pollutant, highlighting the importance of tailoring the process to fit the local wastewater characteristics and as part of a treatment train system. Specifically, maximum P removal was achieved after 5 min of mixing, using 1 g L−1 of feed, 123 mg L−1 initial phosphate concentration, pH 8 – 10, and was not affected by temperature variations; whereas, for ammonia removal, optimal conditions were 180 min, 16 g L−1 feed dosage, 80 mg L−1 initial concentration, pH 10 and temperature > 45 °C. The optimal conditions for the removal of both pollutants from real wastewater were 30 min, 6 g L−1 dosage, and ambient temperature and pH. Furthermore, Mg and Ca concentration was found to influence the process. Reduction in total dissolved solids (TDS) and electrical conductivity (EC) suggest an attenuation of chemical species. Characterisation revealed that the product mineral obtained under the optimal conditions for pollutants removal is rich in quartz, periclase, brucite, calcite, magnesite, and struvite. This was further supported by the FTIR results, which indicated the presence of Mg–O, PO 4 3 − , N–H and OH stretches. In addition, the EDS verified the presence of Mg, Ca and P in product mineral. Results are suggestive of the high efficiency of the mechano-thermo activated magnesite treatment process for phosphate and ammonia removal and struvite crystallization. Thus, this technology could valorise municipal wastewater effluents and open new horizons for the effective and sustainable management of wastewater effluents, since struvite can replace the mined phosphate fertilizers, which are rapidly depleting, in the agriculture industry. Image 1 • Phosphate and ammonia were effectively removed from real municipal wastewater. • An integrated process based on mechano-thermo activated magnesite was employed. • Magnesium ammonium phosphate (struvite) was recovered as a process co-product. • The treatment time, feed dosage, concentration, pH, and temperature were examined. • The process was optimised and could be used for treating and valorising wastewater. [ABSTRACT FROM AUTHOR]

The biodegradation of oil sludge from Mexican sour gas and petrochemical facilities contaminated with a high content of hydrocarbons, 334.7 ± 7.0 g kg−1 dry matter (dm), was evaluated. Studies in microcosm systems were carried out in order to determine the capacity of the native microbiota in the sludge to reduce hydrocarbon levels under aerobic conditions. Different carbon/nitrogen/phosphorous (C/N/P) nutrient ratios were tested. The systems were incubated at 30 °C and shaken at 100 rpm. Hydrocarbon removals from 32 to 51% were achieved in the assays after 30 days of incubation. The best assay had C/N/P ratio of 100/1.74/0.5. The results of the Microtox® and Ames tests indicated that the original sludge was highly toxic and mutagenic, whereas the best assay gave a final product that did not show toxicity or mutagenicity. [Copyright &y& Elsevier]