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[Display omitted] • A gravity-driven EDMBR was developed using stainless-steel mesh as anodic membrane. • Optimized external voltage supporting superior performance was 1.2–1.6 V. • Electrostatic adsorption enabled rapid formation of dynamic membrane. • Electro-oxidation contributed to well-structured DM showing low-fouling properties. • Sacrificial anode induced electro-coagulation enhanced phosphorus removal. Gravity-driven dynamic membrane bioreactor (DMBR) process has emerged as a promising wastewater treatment technology. However, long dynamic membrane (DM) formation time, membrane fouling and low phosphorus removal have limited its widespread application. A novel gravity-driven electro-DMBR (EDMBR) using stainless-steel meshes as the anodic membrane and graphite plates as the cathodes was developed for domestic wastewater treatment, with process performance, DM properties and energy consumption compared with a control DMBR without external voltage applied. Electrostatic adsorption between negatively charged foulants and positively charged anodic membrane shortened DM formation time to less than 4 min. Afterwards, electro-oxidation effect and biodegradation effect resulted from the enrichment of electroactive microorganisms (such as Pseudomonas , Acinetobacter , Exiguobacterium) ensured continuous degradation of attached foulants and maintained a thin and well-structured DM layer, showing higher stable flux and reduced cleaning frequency at the voltage of 1.2 V and 1.6 V compared to the control DMBR. The electro-coagulation (EC) effect originated from iron releasing modified the sludge properties and enhanced phosphorus removal (74 %-87 %). Moreover, the EDMBR with higher permeability and treatment capacity resulted in lower energy consumption (0.41–0.44 kWh/m3) compared to the DMBR (0.50 kWh/m3). The results provide new insights into sustainable operation of the EDMBR process towards lower energy demand and less maintenance requirement. [ABSTRACT FROM AUTHOR]

• Four carbon-efficient nutrient removal processes were integrated in one system. • Substantial external carbon and aeration energy were saved. • The energy-intensive mixed liquor recirculation can be eliminated. • Smart control system handled highly variable influent quality and low temperature. In order to maximize carbon efficient nutrient removal of real primary effluent under the conditions of highly variable influent quality and low temperature, this study integrated four advanced bioprocesses, namely partial nitrification, endogenous denitrification, partial denitrification-anammox, enhanced biological phosphorus removal, into one advanced pilot design. The pilot system has been on-site operated for 212 days and was able to handle highly variable conditions with the aid of automatic feedback and feedforward controllers nested in secondary and tertiary treatment. Comparing to the case when full nitrification and full dentification technologies had to be used to meet the effluent requirement of total inorganic nitrogen (TIN) ≤ 3 mg/L and orthophosphate phosphorus ≤ 0.1 mg/L, the pilot results showed that 100 wt% carbon and 55.5 wt% oxygen could be saved in the secondary process and another 45.2 wt% carbon could be saved in the tertiary process. 44.5 wt% influent TIN was removed through endogenous denitrification in the secondary treatment with another 39.5 wt% TIN polished by partial denitrification-anammox in tertiary treatment. Because post-anoxic endogenous denitrification has removed majority of the NO X -N, it was concluded that the energy intensive mixed liquor recirculation that has been popular in traditional design for pre-anoxic zone denitrification can be eliminated. [ABSTRACT FROM AUTHOR]

Phosphorus is an important element for both animals and plants, but its excess can cause eutrophication in water. Excess phosphorus is present in wastewater mainly due to acid rain, the dissolving of rocks, and agricultural waste. There are many methods for the elimination of Phosphorus from aqueous solution, but their use is finite because of the high operational cost. Adsorption is a productive and popular method for removing phosphorus from aqueous solution. In this study, Vachellia nilotica sawdust and its different composites (Ppy/SD and MG/SD) were utilized for the effective adsorption of phosphorus from the solution. Prepared sorbents were characterized via BET, SEM, FTIR and XRD for their surface area and morphological, functional and crystallinity attributes. Adsorption tests were carried out to identify the optimal working parameters such as adsorbent dose, temperature, initial phosphorus concentration, pH, and contact time. Adsorption isotherm and kinetic model were accurately explained by the Langmuir model and pseudo 2nd order kinetics. The maximal adsorption capacity for Phosphate was 4.803, 5.32, and 6.27 mg/g for Native/SD, Ppy/SD, and MG/SD, respectively. Thermodynamic characteristics confirmed that the phosphorus adsorption was endothermic and spontaneous. Thus, sawdust is an eco-friendly and inexpensive adsorbent for phosphorus removal from wastewater. [Display omitted] • Adsorption of phosphate ions using Vachellia nilotica sawdust-based biocomposites. • Recorded adsorption capacities were in order: Native/SD < Ppy/SD < MG/SD. • Phosphate ions adsorption mechanism examined by equilibrium and kinetics. • Fabricated biocomposites exhibited promising potential in wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel nitrogen and phosphate-removing fungus was isolated. • Nitrogen was removed through assimilation and HN-AD. • Different phosphorus species deposited in cell membranes and EPS. • Removal pathway of nitrogen and phosphate were revealed. Fungi capable of simultaneous nitrogen and phosphorus removal from wastewater is rarely found. Here, a novel fungal strain (SNDM1) performing heterotrophic nitrification, aerobic denitrification, and phosphate removal was isolated and identified as Mucor circinelloides. The favorable nutrient removal conditions by the strain using glucose were C/N ratios of 25–30, salinities of 0 %–3 %, and pH of 7.5. Strain SNDM1 achieved ammonium, nitrite, nitrate, and phosphate removal rates of 5.23, 10.08, 4.88, and 0.97 mg/L/h. Nitrogen balance indicated that gaseous (18.60 %–24.55 %) and intracellular nitrogen (43.76 %–70.63 %) were primary fate of initial nitrogen. Enzyme activity revealed that ammonium removal occurred through heterotrophic nitrification and aerobic denitrification. Removed phosphorus was mainly transformed into cell membranes (56 %–64 %) and extracellular polymeric substances (20 %–26 %). Orthophosphate was the major intracellular phosphorus species, while polyphosphate and pyrophosphate existed extracellularly. These findings highlight the potential of this fungal strain for bioremediating polluted wastewater. [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]

The magnesium phosphate (Mg-P) crystallization based on anaerobic ammonia oxidation is of interest for simultaneous nitrogen and phosphorus removal in wastewater treatment due to cost-effectiveness. Understanding the role of extracellular polymeric substances (EPS) in crystal growth is pivotal for bio-induced Mg-P crystallization. In this work, the effects of EPS in Mg-P crystallization were thoroughly investigated. Results indicated that EPS decreased the initial crystallization rate but slightly improved the final crystallization yield. The maximum removal efficiencies of Mg and P ions increased by 2.8 % and 3.1 %, respectively, when EPS concentration was 80 mg/L. Additionally, the presence of EPS enhanced Mg 3 (PO 4) 2 ·10 H 2 O production and facilitated the formation of larger rhombic plate-like structures crystals (maximum particle size increased by 215 %). Analysis of EPS composition changes during the crystallization process and characterization of the final crystals suggested that tryptophan-like proteins preferentially involved in the Mg-P crystallization process, while β-sheet proteins potentially influencing crystal morphology. Furthermore, the formation of phosphate ester groups, hydrogen bonding, and COOH-Mg2+ complexes were considered triggering factors for the interaction between EPS and Mg-P crystals. This study elucidated the underlying mechanism of EPS on Mg-P crystallization, further enhancing the understanding of the interaction between inorganic mineralization processes and microorganisms. [Display omitted] • Extracellular polymeric substances (EPS) affected Mg-P crystallization. • EPS promoted the generation of more Mg 3 (PO 4) 2 ·10 H 2 O. • EPS facilitated the formation of larger and thicker crystals. • The interaction between EPS and Mg-P crystals was elucidated. • Tryptophan-like and β-sheet proteins were mainly responsible for the interaction. [ABSTRACT FROM AUTHOR]

Supplementing carbon sources in sewage treatment plants with organic matter from food waste is crucial for resource recycling in coal mining areas. In this study, a moderate-temperature H 2 O 2 method was used to pretreat food waste from a coal mining area. The changes in the properties of the pretreated food waste and their influence on volatile fatty acids (VFAs) production during anaerobic fermentation were investigated. Additionally, the nitrogen and phosphorus removal rates obtained when glucose and fermentation slurry of food waste (FSFW) were used as carbon sources in the sewage treatment system were compared. Compared with untreated food waste, the soluble chemical oxygen demand (SCOD) increased by 58 % after pretreatment with 0.25 % H 2 O 2 at 60 ℃, and the viscosity and oil content decreased significantly, which caused VFAs production to increase from 15,267 mg COD/L to 50,774 mg COD/L. When the H 2 O 2 concentration increased to 2.0 %, the SCOD increased to 153 %, and the viscosity and oil content further decreased, but the VFAs production decreased to 7477 mg COD/L. This occurred because large quantities of ammonia nitrogen was formed at higher H 2 O 2 doses, which inhibited VFAs formation. Moreover, the nitrogen removal rate was higher when FSFW was used as a carbon source than when glucose was used as a carbon source. [Display omitted] • The properties of food waste changed sharply after pretreatment with H 2 O 2 at 60 ℃. • The VFAs yield changed substantially with the change in food waste properties. • VFAs yield increased from 15.3 to 50.8 g COD/L after pretreating by 0.25 % H 2 O 2 -60 ℃. • Fermentation slurry of food waste from mining areas is an effective carbon source. [ABSTRACT FROM AUTHOR]

Anaerobic digestion coupled with micro electrolysis was employed to enhance biological anaerobic phosphorus removal. The anaerobic reactor with the micro electrolysis material maintained a relatively lower total phosphorus (TP) in the digestion mixture and a higher PH 3 content in the digestion gas than the control system with no filler, which facilitated phosphorus removal due to PH 3 formation. The PH 3 release was positively correlated with indicators such as H 2 content, COD concentration, and activity of the electron transfer system. The addition of Fe-C and Fe-Mn-C fillers promoted the biochemical metabolism of organic substrates, and the digestion systems had lower chemical oxygen demand, total nitrogen, and TP during continuous operation. The average TP in the control system was 7.0 mg L−1 from 11 d to 40 d; however, the mean values in the Fe-C and Fe-Mn-C systems were 5.1 and 4.7 mg L−1, respectively. In a conventional anaerobic digestion system, electrons and hydrogens preferentially transfer to sulfate to produce H 2 S, resulting in a decrease in reducing power. As micro electrolysis material was added to the wastewater, the dissolved Fe2+ or Mn2+ ions combined with sulfur ions to form sulphide precipitates, mitigating the biological toxicity derived from H 2 S and reducing the consumption of reactive hydrogen. Hence, electrons and hydrogen accumulate and subsequently facilitate the reduction of PH 3 formation and methane synthesis. This study provides new insights into the biological dephosphorisation of wastewater. • Micro electrolysis was introduced to anaerobic system to remove phosphorus. • Synergistic system facilitated phosphorus removal due to PH 3 formation. • Micro electrolysis material promoted biochemical metabolism of organic substrates. • Fe-Mn-C fillers mitigated H 2 S biological toxicity and facilitated PH 3 formation. • A pathway of enhanced anaerobic biological phosphorus removal was proposed. [ABSTRACT FROM AUTHOR]

The world is predicted to face serious threats from the depletion of non-renewable energy resources, freshwater shortage, and food scarcity. Microbial fuel cells (MFCs) are innovative bio-electrochemical devices capable of directly converting chemical energy into electrical energy using microorganisms as a catalyst. This ability has been explored for generating electricity using wastewater as an energy source, while simultaneously treating wastewater. On the other hand, hydroponics is the cultivation of plants in water without soil. The goal of this study was to develop a novel integrated microbial fuel cell-hydroponic system (MFC-Hyp system) that possesses the ability to concurrently generate electricity while degrading organic pollutants (Chemical oxygen demand, COD) in wastewater, remove and recover nutrients (phosphorus, P and nitrogen, N) from the wastewater, and produce edible plants. The MFC-Hyp system developed in this study produced a power density of 250.7 mW/m2. The power density increased by approximately 19% and the phosphorus recovery increased to 7.5% in the presence of Allium tuberosum compared to 4.9% without the plant (e.g., in the control). The removal efficiencies of nitrate, phosphate, and COD are 32%, 11%, and 80%, respectively. The results indicate that the novel integrated MFC-Hyp system can remove COD from wastewater, generate electricity using wastewater as an energy source, and utilize nutrients for growing plants; however, this system requires further improvement for field implementation. [ABSTRACT FROM AUTHOR]

The combination of activated sludge and microalgae in a membrane bioreactor (MBR) is a new promising solution in municipal wastewater treatment to remove nitrate (NO3−) and phosphate (PO43−). Furthermore, municipal wastewater contains a considerable amount of NO3− and PO43− , which is suitable for microalgae growth. It can be concluded from the literature that there is a direct relationship between microalgae biomass production and nutrient removal. Thus, the light cycle and the initial microalgae concentration (as two main factors for microalgae growth) can be optimized. In this study, the biomass productivity in three light-dark (L-D) cycles (h) (24-0, 16-8, and 12-12 h) and initial concentrations (0.5, 1, and 1.5 g·L−1) were measured. The L-D cycle of 24-0 and the initial concentration of 1 g·L−1 was used as the chosen parameter in the membrane photobioreactor (MPBR) containing microalgae. The initial concentration of nitrate, phosphate, chemical oxygen demand (COD), and total dissolved solids (TDS) was investigated. The investigation was performed first on the MBR containing activated sludge and then on the treated wastewater via MBR to MPBR containing microalgae (MBR-MPBR). The duration of the experiment was 133 days. During this period, the removal amount of COD, nitrate, and phosphate was reported at 92.35%, 47.55%, and 36.46% in the MBR, respectively. In MBR-MPBR, the average of nitrate and phosphate removal increased to 93.88% and 88.44%, respectively. However, TDS did not show any notable alterations in both operating systems. According to the findings, the second stage of the treatment process, MBR-MPBR outperformed the MBR system in terms of NO3− and PO43− removal. A membrane bioreactor is a combination of the membrane with microorganisms used in the wastewater treatment process. Due to their simple structure, small size, and high efficiency in removing organic and inorganic substances, membrane bioreactors have been considered for industrial and urban wastewater treatment. Operational parameters in the design of these systems have a significant impact on nutrient removal efficiency. Furthermore, based on the high efficiency of microalgae in removing nutrients, its combination with activated sludge increases the efficiency of the bioreactor. In this work, some operating parameters such as the light-dark cycle and initial concentration of microalgae were optimized in the membrane bioreactor. Then, two various systems, namely a membrane bioreactor (containing activated sludge) and a two-stage membrane bioreactor (containing activated sludge and microalgae), were compared. In this regard, the total dissolved solids, chemical oxygen demand, nitrate, and phosphate removal were investigated. All these values were recorded under optimal conditions of the light-dark cycle and initial concentration of microalgae in two different systems. [ABSTRACT FROM AUTHOR]

In this study, a new Fe-rich carbon composite derived from iron-poisoned waste resin (WRC) was successfully prepared via pyrolysis-activation to remove phosphate from wastewater. The physicochemical properties of WRC were characterized using multiple characterization tools. The results showed that the WRC had a large specific surface area and was rich in metal loading for adsorption. Batch and fixed-bed experiments investigated the adsorption performance of WRC. The maximum adsorption capacity calculated from the Langmuir model was 17.43 mg/g at 298 K. Kinetics experiments showed that the adsorption of phosphate by WRC accorded with pseudo-second-order kinetic model. The WRC could maintain excellent adsorption performance in a wide pH range of 2–12, suitable for various wastewater conditions. Meanwhile, the WRC had well anti-interference of common anions and humic acids on phosphate adsorption and WRC reuse performance. The mechanisms of phosphate adsorption by WRC were confirmed to be electrostatic attraction, ligand exchange and Lewis acid-base interaction. Fixed bed experiments were conducted for dynamic treatment of synthetic wastewater and actual wastewater, and the results indicated that WRC had potential application prospect. This study provides an economically feasible method for the phosphate removal from wastewater and achieves the reuse of waste resin. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrochemical methods provide one of the most effective approaches for wastewater treatment. However, the performance of these systems is highly dependent on the type of wastewater to be treated and the electrode material used (including some relatively cheap and readily available materials such as stainless‐steel and copper). Unfortunately, the applicability of stainless steel as anode and copper as cathode electrodes materials for the purification of livestock slaughterhouse wastewater has not been captured in the previous studies. This study investigated the potential of combining stainless steel (anode) and copper (cathode) as electrode materials for the purification of livestock wastewater. The influence of contact time (20, 40, and 60 min) on the pollutants' removal efficiency was also investigated. From the analysis results, it was observed that the contact time and type of pollutant to be removed had a significant influence on the removal efficiency of the electrochemical treatment system. The highest removal efficiency was achieved from the combination of TSS and 60‐min contact time, with 92% removal efficiency. While the lowest removal efficiencies was observed from the combination of phosphates, nickel, aluminum, and ammonia and 10 min contact time; with removal efficiencies of 22.6%, 23.4%, 34.3%, and 34.3%, respectively. However, in terms of general removal efficiency (after 60 min of the contact time), the lowest removal efficiency was observed from ammonia with a removal efficiency of 62.2%. The treatment system also achieved high removal efficiencies for some other parameters such as Turbidity, Color, TSS, COD, BOD, and TOC ranging from 85.5% to 89.2% after 60 min of the contact time. [ABSTRACT FROM AUTHOR]

This study explored the potential application of silica nanoparticles (SiNPs) prepared from rice husk ash (RHA) to reuse phosphate from aqueous solution. The physicochemical analysis illustrated that the SiNPs, which were extracted from waste biomass, have a nonuniform shape with a size range of a few nanometer to hundreds of nanometers, a surface area of 15.56 m2·g−1, and an adsorption pore width of 4.06 nm. Those results carried out the possibility to utilize the SiNPs for removal of phosphate. Findings from the batch sorption experiments showed that the phosphate adsorption was controlled by experimental parameters, i.e., pH, adsorbent dosage, concentration of adsorbate, and adsorption time. The experimental results showed that the maximum phosphate adsorption capacity of SiNPs was achieved at around 9.08 mg·g−1 at adsorption conditions, i.e., pH 7, SiNPs dosage of 0.3 g, and adsorption time of 90 min. The phosphate removal based on SiNPs will offer several benefit such as an effective and low cost method, reliable to reuse as an effective slow release phosphate fertilizer. [ABSTRACT FROM AUTHOR]

In the context of this investigation an assessment was made of the possibility of using magnesium-containing wastes from the production of periclase in environmental engineering protection processes. The efficiency of the removal of phosphate and ammonium ions using powdered brucite, water-soluble magnesium salts, and complex titanium-containing coagulants was evaluated. It was proved that the magnesium-containing reagents are highly efficient in the co-precipitation of hardly soluble magnesium ammonium phosphate and in the purification of high-pH waste waters. Magnesium-containing reagents received approbation on wastewater from re-processing of plastic and production of cement. [ABSTRACT FROM AUTHOR]

Phosphate‐loaded industrial wastewaters have resulted in numerous environmental issues that have hard hit the Gulf of Gabes‐Tunisia, making the environmental protection one of the most compelling priorities. Consequently, this study aimed first to compare the amounts of phosphate adsorbed by two types of Tunisian activated clays. The second goal was to assess and optimize the phosphate removal efficiency of these clays, using Box–Behnken design (BBD) under response surface methodology. Results showed that the highest adsorption amounts of 130.16 mg g−1, 125.42 mg g−1 were yielded for Jebel Haidoudi clay and Douiret clay, respectively. These values demanded an initial phosphate concentration of 300 mg L−1, a contact time of 5 h, and a pH of 2). Thus, kinetic and isotherm studies of phosphate elimination from synthetic solutions demonstrated that for both activated clays, the pseudo‐second‐order and Langmuir equation fitted very well the experimental data, respectively. These results indicate that phosphate adsorption might be mainly a chimisorption phenomenon and a monolayer process. All these findings confirmed that both activated clays could be considered as a competent, cost‐effective, efficient and ecological alternative for the elimination of phosphate from industrial wastewaters. Practitioner Points: Activated clay could be adopted as an efficient and cost‐effective adsorbent.The optimum conditions were nominated as 300 mg L−1 of initial phosphate concentration, 5 h contact times and pH = 2.The probable uptake mechanism of phosphate followed predominantly the acid‐base interaction and hydrogen bond. [ABSTRACT FROM AUTHOR]

Elevated concentration of total phosphorus (TP) or reactive phosphate (PO43−) in aquaculture wastewater (AW) can cause eutrophication in the wastewater discharge ponds. This study delves into the effectiveness of calcined eggshells (CESs) in recovering low concentrations of TP and PO43− from AW. Eggshell waste collected from domestic sources was pyrolyzed at 800 °C for 30 min. Characterization indicated that the functional groups of CES portray a significant role in the adsorption process. The nonlinear form of the Freundlich model fitted well for TP and PO43− adsorption processes from AW. CES could recover up to 96.6 and 97.3% of low concentration TP and PO43−, respectively, from AW. The adsorption indicated chemisorption activity by CES. The thermodynamic studies suggested that the adsorption of TP and PO43− were feasible, spontaneous, and exothermic in nature. This recovery process does not create secondary waste, and the recovered spent adsorbents can be utilized as garden fertilizer or as pest repellant in the aquaculture farm. [ABSTRACT FROM AUTHOR]

A parent Mg-Al-LDH was upgraded in its adsorption properties due to the incorporation of tri-metal species oxy(hydroxide) nanoparticles obtaining Mn2+/Zn2+/Fe3+/Mg-Al-LDH composite for the phosphate recovery from simulated urban treated wastewater. The physicochemical properties of the synthesized Mn2+/Zn2+/Fe3+/Mg-Al-LDH make promising for real application without being environmentally harmful. The performance of Mn2+/Zn2+/Fe3+/Mg-Al-LDH composite was evaluated through batch adsorption assays. The support of iron, manganese, and zinc (oxy)hydroxide nanoparticles onto the parent Mg-Al-LDH structure was performed by precipitation, isomorphic substitution, and complexation reactions. The main improvement of the Mn2+/Zn2+/Fe3+/Mg-Al-LDH composite was the highest phosphate adsorption capacity (82.3 mg∙g−1) in comparison to the parent Mg-Al-LDH (65.3 mg∙g−1), in a broad range of concentrations and the effective phosphate adsorption at neutral pH (7.5) near to the real wastewater effluents conditions in comparison to the conventional limitations of other adsorbents. The effectiveness of Mn2+/Zn2+/Fe3+/Mg-Al-LDH composite was higher than the conventional metal LDHs materials synthesized in a single co-precipitation step. The phosphate adsorption onto Mn2+/Zn2+/Fe3+/Mg-Al-LDH composite was described to be governed by both physical and chemical interactions. The support of Mn2+/Zn2+/Fe3+ oxy(hydroxide) nanoparticles over the parent Mg-Al-LDH was a determinant for the improvement of the phosphate adsorption that was governed by complexation, hydrogen bonding, precipitation, and anion exchange. The intra-particular diffusion also described well the phosphate adsorption onto the Mn2+/Zn2+/Fe3+/Mg-Al-LDH composite. Three specific stages of adsorption were determined during the phosphate immobilization with an initial fast rate, followed by the diffusion through the internal pores and the final equilibrium stage, reaching 80% of removal and the equilibrium within 1 h. The Mn2+/Zn2+/Fe3+/Mg-Al-LDH was strongly selective towards phosphate adsorption in presence of competing ions reducing the adsorption capacity at 20%. The Mn2+/Zn2+/Fe3+/Mg-Al-LDH has limited reusability, only 51% of the adsorbed phosphate could be recovered in the second cycle of the adsorption-desorption process. Around 14% of phosphate was loosely-bond to Mn2+/Zn2+/Fe3+/Mg-Al-LDH which brings the opportunity to be a new source of phosphorus. The use of eluted concentrates and the final disposal of the exhausted adsorbent for soil amendment applications can be an integral nutrient system (P, Mn, Zn, Fe) for agriculture purposes. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: One of the negative impacts of polluting activities on aquatic ecosystems is the loss of its natural self-purification ability, for this reason, the purpose of this research was to evaluate the Sinú River capacity to assimilate wastewater discharges. METHODS: Monitoring of several water quality parameters was carried out in the river at different seasons and a numerical method was used to simulate different scenarios through the Environmental Fluid Dynamics Code model. The model calibration process was tested applying the Root Mean Square Error and after calibrating the model, scenarios of increase and decrease of discharge concentrations and flows, and river flows were simulated. Finally, the results were compared to water quality reference limits. FINDINGS: Results show that the model accurately represented the real conditions of the studied river section for all the evaluated parameters. Also, assimilative capacity was affected mostly by the scenario in which the river flow was decreased by 50%, and the flows and discharges concentrations were increased five times; causing parameters such as ammonia nitrogen, chemical oxygen demand, phosphates, and total nitrogen, to exceed the established reference limits with maximum concentrations of 2.7 mg/L, 30.9mg/L, 0.98 mg/L and 6.3 mg/L; respectively. Higher concentrations of water quality parameters were mostly found in the dry season since lower velocities and river flows promote less pollutants mixing and dilution processes. CONCLUSION: The model spatiotemporal simulations showed the effect of the wastewater discharges on the Sinú River assimilative capacity and made it possible to find those scenarios where water quality parameters exceeded the reference limits, becoming an essential tool for water management and the development of strong water quality objectives by stakeholders and environmental authorities. [ABSTRACT FROM AUTHOR]

Nowadays, there are more than fourteen major state and private owned textile industries and garment factories in Ethiopia. However, these textile effluents are directly discharged without treatment to the surrounding environment, as a result, the pollutants bring serious problem to the surrounding community including health such as skin diseases, asthma, abortion, carcinogenic effect, biodiversity loss and mutagenic effect on the. The main objective of this study is characterization and treatment of the textile effluent using aluminum electrodes in the electrocoagulation process. EC experimental setups were designed and different parameters were optimized. Electrocoagulation treatment process eliminates physicochemical quality indicators such as pH, electrical conductivity (EC); turbidity, biological oxygen demand (BOD), ammonia; nitrate, nitrite, total nitrogen (TN) and phosphate were determined using standard procedures. From the result, the maximum removal efficiency of phosphate, ammonia, TN, electrical conductivity, turbidity and BOD were obtained 97, 87, 88, 89, 99 and 66%, respectively. Analyses of the electrochemically generated sludge by X-ray Diffraction, Scanning Electron Microscope (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) revealed that the expected crystalline aluminum oxides (bayerite (Al(OH)3 diaspore (AlO(OH)) were found in the sludge. The amorphous phase was also found in the floc. Therefore, a treatment technology was good and encourages the community to apply the technique for the treatment of textile effluent before discharging into the environment. [ABSTRACT FROM AUTHOR]

As the main solid waste of wastewater treatment plants (WWTPs), sewage sludge has the characteristics of large output and high contents of organic matter and inorganic metals. In this study, sewage sludge was used as raw material to prepare a unique sludge-based biochar. In order to obtain the best modification method for ammonium and phosphorus adsorption removal in wastewater, the sludge-based biochar was modified by loading four kinds of metal, respectively, including Mg, Al, Fe, and Mn, to improve the adsorption capacity of the biochar. A large number of adsorption experiments showed that Mg-modified sludge–based biochar (BC-Mg) had the best adsorption effect. At 25°C, the maximum adsorption capacity of NH4+ and PO43− reached 30.58 and 400.00 mg·g−1 , respectively. In the double-solute coadsorption experiment, Mg-BC also had the best adsorption effect. In addition, kinetics, isotherms, and various characterization analyses [Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and zeta potential, among others] were used to study the physicochemical properties of the modified sludge–based biochar and the adsorption mechanism of NH4+ and PO43−. It mainly includes ligand exchange, ionic bond, deposition reaction, and electrostatic attraction to pollutants. This study not only provides a feasible strategy for efficient utilization of sewage sludge resources, but also provides a practical method for ammonium and phosphorus removal in water. [ABSTRACT FROM AUTHOR]

Herein, magnesite slags (MS), which remain after sulfuric acid extraction from light burnt magnesite in the magnesite industry, were used as phosphate adsorbents in wastewater. The MS were calcined under 700 °C to enhance phosphate adsorption. The calcined magnesite slags (CMS) were characterized by nitrogen adsorption–desorption isotherm, X-ray diffraction, and scanning electron microscopy. A series of batch adsorption experiments were carried out to test the phosphate adsorption capacity of CMS. The results showed that the calcific treatment promoted the conversion from Mg, Ca, Fe, etc. compound to metal oxide of the MS. The generated metal oxide particles resulted in 237.4 mg/g increase in the phosphate adsorption capacity. The phosphate adsorption isotherm of CMS fitted the Langmuir model better, and the maximum adsorption capacity of CMS was 526 mg/g. The adsorption kinetics of phosphate on CMS can be described by the pseudo-second-order model. The phosphate removal efficiency was greater than 98% in 300 mg/L phosphate solution. Mechanism investigation results indicated that phosphate was adsorbed by CMS through MgO protonation, electrostatic attraction, Mg-P complexation, and ligand exchange. The results obtained in this work demonstrate that the CMS is a potential effective adsorbent for removal and reutilization phosphate from P-contaminated water, due to it can be employed as a fertilizer after phosphate adsorption. [ABSTRACT FROM AUTHOR]

Highlights: Tailored La-based particles (La-CZ) sorb phosphate in wastewater. The adsorption capacity of La-CZ particles was 18.2 mg g−1 (PO43−). The adsorbed phosphate mainly existed in a stable state. La-CZ particles were recovered easily in the small-scale reactor designed in this study. Effluent concentrations <0.1 mg/L PO43− were achieved in the reactor when treating river water. It is crucial to develop an effective and easily recoverable phosphate absorbent for the control of eutrophication problems in polluted rivers. In this study, a stable particulate adsorbent with a diameter of 5 mm synthesized from lanthanum, activated carbon, and zeolite (La-CZ) was developed, characterized, and tested for the removal of phosphate from wastewater in a small-scale reactor, which was designed to easily recycle La-CZ with a basket. Batch studies showed that La-CZ could reach adsorption equilibrium within 2 h and the maximum phosphate sorption capacity was 18.2 mg g−1. The experimental data showed good compliance with the Langmuir isotherm model and pseudo-second-order kinetic model, implying that chemisorption dominates the phosphate uptake process. La-CZ exhibited a stable adsorption capacity over a wide pH range (3–7), while the adsorption capacity decreased slightly under alkaline conditions. Although Nitrates (NO3−) and Carbonate (CO32−) had some effects, normal coexisting ions such as Chloride (Cl−), Sulfate (SO42−), and Fluorine (F−) had no significant effects on the phosphate adsorption capacity of La-CZ. The main form of phosphate removed from the reaction system was HCl-P (77.68%), as determined through phosphorus fractionation. In particular, this study designed a replaceable filler-type reactor integrating a reflux and aeration system, 98.8% of phosphorus could be removed from actual wastewater, and La-CZ could be reclaimed easily. This work provides an excellent reference for particulate adsorbents that can efficiently remove phosphate in practical applications in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND: Photogranules seem to be an alternative solution for wastewater treatment and biomass harvesting. The aim of our work was to investigate the formation of algal flocs as an efficient method for the treatment of wastewater and separation of algal cells. RESULTS: The progressive change of activated sludge to algal flocs was evaluated under static and stirring conditions using a synthetic substrate (modified Blue Green‐11 medium) and the secondary effluent from an activated sludge wastewater treatment plant. Algal flocs were observed in all cultures by day 10 and a high chlorophyll concentration was detected in all cases reaching values up to 610–630 μg L−1 at the end of the experiment after 30 days. The size of flocs in all cultures at either static or mixing conditions ranged from 330 to 994 μm, resulting in biomass concentration from 330 to 660 mg L−1. The cultures in secondary effluent at static conditions presented the greatest size, and the mean diameter on days 10 and 30 was 250 and 994 μm, respectively. The cultures were efficient in nutrient removal and, by the end of the experiment, nitrates and phosphates were completely consumed. CONCLUSIONS: Algal flocs were developed from activated sludge without adding any other flocculant and a highly efficient biomass was developed, which can easily settle and remove nutrients from the medium. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

In our previous work, efficient PO43− and NO3− adsorption by calcined Meretrix lusoria powder was reported. This study addressed pilot-scale application of M. lusoria F800 for PO43− and NO3− removal from the real site. The study investigated the performance of multicomponent (PO43− and NO3−) adsorption from domestic wastewater (DWW) in fixed bed adsorption column packed with Meretrix lusoria F800 beads. Prior the packing, M. lusoria F800 beads were successfully tested for 20 mg/L PO43− and NO3− removal from synthetic wastewater (SWW) and DWW, respectively. In this research study, the effect of the column operational parameter including DWW influent flow rate (Q: 10, 30, and 40 mL/min) and adsorbate concentration (C: ≈ 60 mg/L) on breakthrough curves was well-evaluated. Thomas model was used to confirm the correlations of the experimental data with the maximum adsorption capacity of 23.6 mg/g PO43− and 9.31 NO3− mg/g, at 10 mL/min flow rates, respectively. Results demonstrated that Thomas model well interpreted the experimental data. Moreover, PO43− and NO3− removal capacity by regenerated M. lusoria F800 beads was observed additional adsorption cycle. Furthermore, scale-up column was successfully tested, where experimental values were in parallel with theoretical values. In conclusion, this study indicates that M. lusoria F800 beads can be economically and easily utilized in a fixed bed adsorption column for the removal of PO43− and NO3− from DWW containing excessive PO43− and NO3−. [ABSTRACT FROM AUTHOR]

While phosphorus is a limited resource that is essential for agriculture, its release to the environment adversely impacts water quality. At the same time, animal wastewaters contain significant quantities of phosphorus and nitrogen that can be recovered for beneficial use. Phosphorus uptake experiments were performed with magnesium-treated corn-cob char and with magnesium silicate prepared using silicate from rice straw at pH 8 and 9. The concentration of dissolved phosphorus as a function of total added ammonium chloride (NH4Cl) was determined, and chemical equilibrium modeling was used to investigate the concentration trends of dissolved and mineral species. According to chemical equilibrium modeling, carbonate alkalinity exerted a significant magnesium demand, with approximately half of all added magnesium forming magnesite (MgCO3(s)). As total added NH4Cl increased, excess Cl− complexed with dissolved Mg2+ in competition with orthophosphate, freeing orthophosphate to precipitate, mainly as the mineral struvite (NH4MgPO4·6H2O(s)). As the concentration of added NH4Cl increased by a factor of ten, measured concentrations of dissolved phosphorus decreased by a factor of ten, meaning that ionic composition has the potential to significantly impact the amount of phosphorus that can be recovered from wastewaters for beneficial use. [ABSTRACT FROM AUTHOR]

Phosphorus is a commonly used compound in coatings; thus, wastewater from coating plants usually contains large amounts of phosphate. Given its unidirectionality in the ecological cycle, phosphorus must be removed from coating wastewater and recycled. Herein, phosphorus was removed and recovered from industrial coating wastewater through chemical precipitation. The effects and mechanisms of this removal and recovery using the iron salt, calcium salt, and iron-calcium salt methods were analyzed. When the proportion of iron in iron-calcium salt exceeded 0.51, the average phosphorus removal rate was more than 62.44% of the average removal rate when the iron salt or calcium salt was used alone. A synergistic phenomenon was demonstrated with the iron-calcium salt method; the phosphorus removal rate reached 96.13% when the molar ratio of iron-calcium salt to phosphorus was 1.50. The precipitation floccules produced using the iron-calcium salt integrated the advantages of the iron and calcium salt methods; they had a large particle size and were easily crystallized. This study demonstrates a valuable method for the removal and recovery of phosphorus from industrial coating wastewater. [ABSTRACT FROM AUTHOR]

The article discusses the resource utilization of Fe-rich sludges. Topics discussed include an explanation of Fe-rich sludges which a waste product of water treatment, hydrometallurgy, surface finishing, and dye chemical industries; discussed further purification of sludge for creating new commercial products including red and black dyes, an iron concentrate powder, etc. and mentions a table characterizing the types of Fe-rich sludges.

The purpose of this study was to eliminate phosphate (P) from wastewater using MnFe2O4 nanoparticles. BET, TGA/DTG, FTIR, SEM, TEM, VSM, XRD and EDX/Map analyses were used to determine the MnFe2O4 surface properties. The specific surface area of the adsorbent was 196.56 m2/g and VSM analysis showed that the adsorbent has a ferromagnetic property. The maximum P sorption efficiency using MnFe2O4 (98.52%) was achieved at pH 6, temperature of 55 °C, P concentration of 10 mg/L, time of 60 min, and sorbent dosage of 2.5 g/L, which is a significant value. Also, the thermodynamic study indicated that the P sorption process is spontaneous and endothermic. Moreover, the utmost sorption capacity of P using MnFe2O4 was 39.48 mg/g. Besides, MnFe2O4 can be used for up to 6 reuse cycles with high sorption efficiency (>91%). Also, MnFe2O4 was able to remove phosphate, COD, and BOD5 from municipal wastewater with considerable removal efficiencies of 82.7%, 75.8%, and 77.3%, respectively. [ABSTRACT FROM AUTHOR]

An adsorbent of weak magnetic La(OH) 3 modified platanus biochar (La-MB) was synthesized for phosphate (P) removal by iron lanthanum sequential modification method for the first time. Compared with synchronous modification method, La-MB had higher P adsorption capacity and similar magnetic separation property. The performance of La-MB was evaluated in terms of adsorption isotherms, adsorption kinetics, coexisting competitive substances, regenerative ability, and it as fixed-bed column filler to remove P from actual wastewater. The results showed that La-MB had a monolayer P adsorption capacity of 116 mg/g in the pH range of 3.0–9.0 at 35 ℃ with the contact time of 45 min, and the adsorption capacity was higher than most La-modified magnetic adsorbents. The coexisting SO2– 4 , NO- 3 and Cl- had no effect, while the HCO- 3 , CO2– 3 and humic acid interfered with the removal of P due to competition for active sites on the surface of La-MB. Moreover, approximately removal efficiency of 97% was remained after three adsorption-desorption cycles in 1.0 mol/L NaOH eluent, which showed the outstanding stability and cyclic utilization. The maximum treatment bed-volumes (BV) under influent flow rates of 0.5 mL/min, 1.0 mL/min and 1.5 mL/min were 3050 BV, 2000 BV and 1100 BV, respectively. The characterization results of zeta potential, FTIR and XPS revealed that the P adsorption of La-MB was dominated by ligand exchange, inner sphere complexation and electrostatic attraction. All results indicated that La-MB could serve as a promising adsorbent for the efficient removal of P from actual wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

The discharge of industrial effluent constituting high orthophosphates and organic pollutants in water receiving bodies compromises freshwater quality and perpetuates eutrophication. In this study, an anaerobic–aerobic sequencing batch reactor (SBR) under activated sludge was investigated for orthophosphates and chemical oxygen demand (COD) removal from brewery wastewater. Raw brewery wastewater samples were collected on a daily basis for a period of 4 weeks. The findings of the study are reported based on overall removal efficiencies recording 69% for orthophosphates and 54% for total COD for a sludge retention time (SRT) of 7 days and hydraulic retention time of 18 h at mesophilic temperature conditions of ±25 °C. Moreover, the SBR system showed stability on orthophosphate removal at a SRT ranging from 3 to 7 days with a variation in organic volumetric loading rate ranging from 1.14 to 4.83 kg COD/m3.day. The anaerobic reaction period was experimentally found to be 4 h with the aerobic phase lasting for 14 h. The SBR system demonstrated feasibility on orthophosphates and COD removal with variation in organic loading rate. [ABSTRACT FROM AUTHOR]

Vermifilter is a cost-effective and environmentally friendly technology for domestic and industrial wastewater treatment. However, filter bed clogging is an operational challenge of vermifilter. The present study was conducted to investigate the impact of different hydraulic loading rates (HLRs) on treatment performance and filter bed clogging of horizontal subsurface flow macrophyte-assisted vermifilters (HSSF-MAVF). Three laboratory-scale horizontal subsurface flow vermifilter reactors planted with Canna indica were used in this study. Each reactor was fed synthetic dairy wastewater with HLRs of 0.66, 1.5, and 2.34 m/day, respectively. Based upon the results of this study, the treatment performance and filter bed clogging of the system were observed to be closely dependent on the applied HLRs. The highest treatment performance (89 ± 2%, 94 ± 2%, 95 ± 4%, and 76 ± 5%, respectively, for COD, TSS, ammonium-N, and phosphate-P) with minimum filter bed clogging (10 ± 2% hydraulic conductivity reduction and 0.19 ± 0.05-cm head loss) was observed in the reactor fed with the lowest HLR of 0.66 m/day. Similarly, the lowest treatment performance (67 ± 3%, 61 ± 4%, 87 ± 2%, and 63 ± 4%, respectively, for COD, TSS, ammonium-N, and phosphate-P) with severe clogging of the filter bed (33 ± 2% hydraulic conductivity reduction and 2.1 ± 0.5-cm head loss) was observed in the reactor fed with the highest HLR of 2.34 m/day. The clog matter (CM) from each filter bed is composed of both organic and inorganic materials, and the quantity of CM varied from 6.46 ± 0.28 to 24.44 ± 1-mg/mL, with protein being the major organic clog matter component. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alkaline anion exchange resin has the capability to alkalize and adsorb Al-P from PAC sludge. • AAER demonstrates excellent capacity for phosphorus extraction after undergoing multiple cycles of regeneration. • Ca 10 (PO 4) 6 (OH) 2 was recovered with a maximum recovery of 90.5 %. Polyaluminum chloride (PAC) is commonly used as a flocculant in wastewater treatment plants to aid in the removal of phosphorus (P) from wastewater. As a result, the P element present in PAC-treated sludge is predominantly in the form of Al-P. This study proposes the use of alkaline anion exchange resin (AAER) as a pretreatment method for PAC-treated sludge to enhance P extraction and achieve cleaner P recovery from this type of sludge. The findings of the study indicate that the optimal concentration of AAER is 12 g/g TS, resulting in a P extraction efficiency of 67.2 %. This represents a 26.5 % increase compared to alkali treatment at the same pH (pH = 12.23). Stepwise extraction analysis and molecular dynamics simulations suggest that during AAER treatment, Al(OH) 3 is converted into dissolved [Al(OH) 4 ]−. These species then agglomerate with PO 4 3− and subsequently get adsorbed by the N(CH 3)+ groups on the AAER. Furthermore, even after undergoing five regeneration cycles, the AAER still exhibits a significant adsorption capacity for P. Ultimately, high-purity Ca 10 (PO 4) 6 (OH) 2 is obtained as the final product with a recovery rate of 90.5 %. Meanwhile, the Al extracted by AAER can be reused as a feedstock for polymerized aluminum chloride. This demonstrates that AAER extraction is a promising and efficient waste management strategy for the clean recovery of P and Al from PAC sludge. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Fe 3 O 4 @CSH-AAO magnetic nanoparticles synthesized via spray-precipitation method. • Fe 3 O 4 @CSH-AAO shows high efficacy in P and F removal and separation from wastewater. • Ca on CSH surface and 3-coordinated Al in AAO are active adsorption sites. • Ionic concentration and size lead to varying adsorption capacities for P and F. A novel mesoporous magnetic nanoparticle adsorbent, Fe 3 O 4 @CSH-AAO, was synthesized using the atomization-precipitation method, effectively removing phosphorus (P) and fluoride (F) from wastewater, particularly from the recirculating water of wet-process phosphoric acid. The adsorbent achieved removal efficiencies of 99.6 % for P and 73.5 % for F under conditions of 20 g/L adsorbent dosage, pH ≈ 4, with initial P and F concentrations at 115 mg/L and 38 mg/L, respectively. Equilibrium adsorption data indicated that the adsorption kinetics followed the pseudo-second-order model for F and the pseudo-first-order model for P. The adsorption isotherms fitted the Langmuir model for P and the Freundlich model for F, with maximum adsorption capacities of 37.86 mg P/g and 6.764 mg F/g at pH 4 and 298 K. The surface properties, functionality, and crystallinity were analyzed using BET, SEM, TEM, XRD, and XRF. Furthermore, XPS analyses and molecular dynamics (MD) simulations elucidated that surface Ca in CSH and the exposed Al atoms on the γ-Al 2 O 3 (1 1 0) surface serve as optimal adsorption sites for P and F. The steric hindrance imposed by phosphorus contributes to its preferentially higher adsorption capacity over fluoride. This study not only presents an effective method for the removal of phosphorus and fluoride suitable for practical applications but also provides deep insights into the adsorption mechanism, highlighting the pivotal role of steric hindrance in facilitating ion adsorption. [ABSTRACT FROM AUTHOR]

The effectiveness of phosphorus (P) removal by sand filters is limited during septic tank effluent (STE) treatment. The elevated effluent P concentrations pose threats to drinking water quality and contribute to eutrophication. The concern of P leaching from sand filters is further exacerbated by the increased frequency of flooding and natural precipitation due to climate change. This study aimed to understand P attenuation and leaching dynamics, as well as the removal mechanisms in sand filters treating STE, offering insights into the design and implementation of P removal/recovery modules to onsite wastewater treatment systems. P attenuation and leaching during STE treatment and rainfall were studied in bench-scale columns (new vs. aged sand). At standard STE loading (1.2 gallon d−1 ft−2), 24–32% removal of total phosphorus (TP) was achieved, while increased P removal efficiency (35–53%) was observed at low loading (0.6 gallon d−1 ft−2) with influent containing 10.3–20.0 mg P L−1. Complete breakthroughs were observed in both aged (12–70 days) and new columns (27–73 days) at test hydraulic loadings. The maximum TP attenuation level was 20.6–45.3 mg P kg−1 and 25.3–33.0 mg P kg−1, in aged and new sand columns, respectively. When simulated rain was applied (15–60 mm h−1), 80–97% of the attenuated P leached out and the leaching dynamics were impacted by rainfall duration rather than the intensity. The highest concentrations of TP (15.6–15.9 mg L−1) were leached out from both columns within the first 2–6 h. Orthophosphate was the dominant P species in treated effluent (83–84%) and leachate (69–88%), demonstrating its significance as the major P form in the discharge. In addition, aged sand (>5 years) accumulated higher levels of Mg, Al, Ca, and Fe, thus enhancing the P attenuation level during STE treatment. Collectively, this study underscored the importance of frequent field monitoring for reliable long-term P removal estimates. [Display omitted] • P attenuation in sand filters is reversible and is impacted by STE loadings. • The extent of P leaching is more impacted by rainfall duration than intensity. • Adsorption is the main P removal mechanism in sand filters treating STE. • P attenuation is enhanced by metal accumulation in sand after long-term STE treatment. • Frequent monitoring is essential to understand the fate and dynamic of P in OWTSs. [ABSTRACT FROM AUTHOR]

Low-carbon and high-efficiency processes for achieving simultaneous nitrogen removal and phosphorus recovery from wastewater are gaining increasing attention from researchers. This study investigated the performance and mechanism of a novel Fe(II)-mediated anaerobic ammonia oxidation (anammox) process characterized by stable nitrogen removal and production of high-value Fe–P crystals (FePs) as byproducts. Fe(II) promotes the synthesis of heme C and enhances the activity of nitrate reduction metabolic genes, which induce nitrate-dependent ferrous oxidation to form a complex Fe–N cycle. In addition, Fe(II) significantly enhanced the phosphorus removal efficiency up to 79.2 ± 6.9% by inducing Fe–P biomineralization. Biomolecular analysis has shown that most iron absorption and transport genes, as well as phosphate transport and regulation genes, are promoted by Fe(II). The composition and microstructure analyses of the anammox granules revealed the formation of FePs that consisted of phosphosiderite (FePO 4 ·2H 2 O), ludlamite (Fe 3 (PO 4) 2 ·4H 2 O), and vivianite (Fe 3 (PO 4) 2 ∙8H 2 O). This study also provides an in-depth illustration of the structural characteristics and formation processes of anammox-FePs granules. Thus, an Fe(II)-induced Fe–N–P metabolic network in an anammox-dominated system was uncovered, offering a feasible approach for simultaneous nitrogen removal and phosphorus recovery. [Display omitted] • A diversified Fe–N–P metabolic network was developed in an anammox-based system. • Fe(II) boosts the generation of valuable Fe–P crystal byproducts. • The evolution process of anammox-FePs granules is elaborated. • The mechanism of Fe(II) in enhancing nitrogen metabolism is discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adding iron salts improved rural wastewater treatment by anaerobic baffled reactor. • Feammox can play a role in removing ammonium and total nitrogen in bioreactors. • Phosphorus was removed via vivianite formation with sludge production minimized. • Iron chemistry-induced nutrient removal saved cost by reducing aeration. An iron-retrofitted anaerobic baffled reactor (ABR) system was developed for the effective treatment of rural wastewater with reduced maintenance demand and aeration costs. Average removal efficiencies of chemical oxygen demand, total nitrogen and total phosphorus of 99.4%, 62.7% and 92.6% were achieved respectively, when the ABR system was operating at steady state. With effective bioreduction of FeIII in the anaerobic chambers, phosphorus was immobilized in the sludge as vivianite, the sole phosphorus-carrying mineral. The FeIII in the recirculated sludge induced Feammox in the ABR reactor, contributing 14.8% to total nitrogen removal. Biophase separation and enrichment of microorganisms associated with iron and nitrogen transformations were observed in the system after Fe dosing, which enhanced the removal of pollutants. The coupling of Feammox and vivianite crystallization to remove nitrogen and phosphorus in an iron-retrofitted ABR would appear to be a promising technology for rural wastewater treatment. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) is a powerful biotechnological tool capable of treating multiple pollutants simultaneously. However, the granulation process and pollutant removal efficiency still need to be further improved. In this study, Fe 2 O 3 - and MnO 2 -surface-modified straw foam-based AGS (Fe 2 O 3 @SF-AGS and MnO 2 @SF-AGS), with an average particle size of 3 mm, were developed and evaluated. The results showed that surface modification reduced the hydrophobic groups of carriers, facilitating the attachment and proliferation of microorganisms. Notably, MnO 2 @SF-AGS showed excellent granulation performance, reaching a stable state about one week earlier than the unmodified SF-AGS. The polymeric substance content of MnO 2 @SF-AGS was found to be 1.28 times higher than that of the control group. Furthermore, the removal rates for NH 4 +-N, TN, and TP were enhanced by 27.28%, 12.8%, and 32.14%, respectively. The bacterial communities exhibited significant variations in response to different surface modifications of AGS, with genera such as Saprospiraceae , Terrimonas , and Ferruginibacter playing a crucial role in the formation of AGS and the removal of pollutants specifically in MnO 2 @SF-AGS. The charge transfer of metal ions of MnO 2 @SF promotes the granulation process and pollutant removal. These results highlight that MnO 2 @SF-AGS is an effective strategy for improving nitrogen and phosphorus removal efficiency from wastewater. [Display omitted] • The straw foam was modified by Fe 2 O 3 or MnO 2. • Carrier modification improved the granulation and N and P removal efficiency. • Functional bacteria of MnO 2 @FS-AGS were Saprospiraceae and Ferruginibacter. • Fe 2 O 3 /MnO 2 @FS-AGS might improve performance by electron transfer. [ABSTRACT FROM AUTHOR]

The main challenge in removing nutrients from municipal wastewater in China is the lack of available carbon sources. While hydrolysis acidification tanks can improve wastewater biodegradability by effectively utilizing internal carbon sources, high sludge concentrations are difficult to control in traditional tank variants. In this study, an innovative anaerobic filter (AnF) hydrolysis acidification reactor composed of a continuously stirred tank reactor (CSTR) and cloth media filter was designed to regulate and maintain high sludge concentrations in the hydrolysis acidifier. The reactor was used as a pretreatment unit for the anaerobic/anoxic/oxic (AAO) units and combined into an AnF-AAO system to explore the effectiveness of internal carbon source utilization in wastewater. The results indicate that as the sludge concentration in the hydrolysis acidifier increased, the hydrolysis and acidification processes became more efficient. The optimal sludge concentration was 40 g/L, which significantly increased the production of soluble chemical oxygen demand and volatile fatty acids. Above this concentration, the efficiency decreased. Compared to traditional AAO processes, the AnF-AAO system achieved superior total nitrogen and phosphorus removal with shorter hydraulic retention times and reduced sludge production by a significant amount of 35%. Due to its capacity for enhancing internal carbon source utilization, the AnF-AAO system constitutes a promising approach for sustainable urban wastewater treatment. [Display omitted] • Variable sludge amounts affect wastewater treatment with hydrolysis acidification. • A novel anaerobic filter reactor was used as pretreatment to regulate sludge amount. • AnF hydrolysis acidification reactor was most efficient at 40 g/L sludge concentration. • The AnF-AAO system improved nutrient removal and reduced sludge by 35%. [ABSTRACT FROM AUTHOR]

Despite the potential of sodium sulfide (Na 2 S) for phosphorus (P) recovery from iron-phosphate waste, the underlying mechanism regarding its impact on P conversion and product quality has not been well addressed. In this study, the effects of Na 2 S addition on P release and recovery from a chemical-enhanced phosphorus removal (CEPR) sludge during anaerobic fermentation were systematically investigated. The results revealed that the effective mobilization of P bound to Fe (Fe–P) by Na 2 S dominated the massive P release from the CEPR sludge, while the organic P (OP) release was not significantly enhanced during anaerobic fermentation. Due to the rapid reaction of Na 2 S with Fe–P and the prevention of Fe(II)–P precipitation by excess S2−, the Fe–P was decreased by 9.7%, 15.2% and 24.9% at S:Fe molar ratios of 0.3, 0.5 and 1, respectively. After anaerobic fermentation, the released P mainly existed as soluble phosphate (SP), P bound to Ca (Ca–P) and P bound to Al (Al–P). The nitrogen and P contents in the fermentation supernatant significantly increased with higher S:Fe ratios, facilitating the efficient recovery of P as high-purity struvite. However, the increased Na 2 S dosage deteriorated the sludge dewaterability because of the dissolution of hydrophilic extracellular polymeric substances and the looser secondary structure of proteins. Comprehensively considering the P recovery, sludge dewaterability and economic cost, the optimal Na 2 S dosage was determined at the S:Fe ratio of 0.3. These findings provide novel insights into the role of Na 2 S in P recovery as struvite from CEPR sludge. [Display omitted] • Effective mobilization of Fe–P by Na 2 S dominated the release of P from CEPR sludge. • Released P was mainly present in soluble phosphate, Ca–P and Al–P. • Dissolution of hydrophilic EPS deteriorated sludge dewaterability. • Struvite with a purity of 67% was recovered from the sludge fermentation supernatant. • The optimal Na 2 S dosage was determined for P release with better dewaterability. [ABSTRACT FROM AUTHOR]

• A continuous self-circulating up-flow granular sludge bed process was introduced. • Accurate self-circulating multiple times and O 2 supply were driven only by aeration. • High up-flow velocity of 7–16 m/h contributed to particle formation and stability. • HRT of 10 h and DO of 0–0.3 mg/L were optimized for higher OLR and energy savings. • Self-circulation driven by aeration is key factor regulating nitrogen removal. Aerobic granular sludge (AGS) capable of nitrogen and phosphorus removal is mainly limited to the applications in sequencing batch reactors. This study introduced an innovative continuous self-circulating up-flow fluidized bed process (Zier process) using separate aeration. The process was composed of an anoxic column (Zier-A), aeration column (Zier-OO) and aerobic column (Zier-O), and was used to treat actual municipal sewage continuously for 170 days. The process achieved self-circulation of 20–32 times and an up-flow velocity within the reactor of 7–16 m/h which were accurately controlled with only separate aeration. The larger proportion of self-circulating multiple times contributed to particle formation and stability, providing hydraulic shear conditions, and screened the precipitation performance of the granular sludge (GS). Meanwhile, the dissolved oxygen (DO) of Zier-O was controlled at 0.1–0.3 mg/L, and the DO of Zier-A input water was zero. The accurate oxygen supply enhanced simultaneous nitrification and denitrification (SND) as well as short-cut nitrification and denitrification in Zier-O and improved the COD utilization rate and the nitrogen removal rate in Zier-A. The COD treatment capacity reached 2.46 kg-COD/(m³·d). With a hydraulic retention time of 10 h, the process consistently ensured that the average concentrations of ammonia nitrogen and total nitrogen in the effluent were maintained below 5 and 15 mg/L, respectively. Moreover, the process maintained the shape and stability of GS, the median diameter of GS ranged between 300–1210 μm, the percentage of mass with particle size distribution < 200 μm at a height of 150 cm within Zier-A and Zier-O accounted for as low as 0.04%–0.05%, and showed good settling performance. The suspended solids in effluent can be maintained at 50–80 mg/L. Overall, the unique structural setting and control method of the Zier process provide another approach for the application of continuous AGS treatment for municipal sewage. [Display omitted] [ABSTRACT FROM AUTHOR]

Understanding the microbial community structure of sludge is crucial for improving the design, operation and optimisation of full-scale wastewater treatment plants (WWTPs). This study aimed to have a comprehensive comparison of microbial communities between aerobic granular sludge and flocculent sludge from two full-scale sequential batch reactors-based WWTPs with nutrient removal for the first time. To better understand key functional bacteria such as polyphosphate accumulating bacteria (PAOs), competitive bacteria such as glycogen accumulating bacteria (GAOs) and nitrifying bacteria for both nitrogen and phosphorus removal, another two full-scale WWTPs with only carbon (C) removal and C and nitrogen (N) removal were compared too. It was found that the richness and diversity of the microbial population in sludge increased with pollutant removal from only C, C and N, to C,N, P removal. For C, N P removal, granule structure led to a more diverse and rich microbial community structure than flocculent structure. Although more abundant nitrifying bacteria were enriched in granular sludge than flocculent sludge, the abundance of total putative PAOs was equivalent. However, the most typical putative PAOs such as Tetrasphaera and Candidatus Accumulibacter seemed to be more correlated with biological phosphorus removal performance, which might be more proper to be used as an indication for P removal potential. The higher abundance of GAOs in flocculent sludge with better phosphorus removal performance might suggest that further investigation is needed to understand the functions of GAOs. In addition, the equivalent abundances of PAOs in the WWTPs with only C removal and with C, N, and P removal, respectively, indicate that many newly reported putative PAOs might not contribute to P removal. This study provides insight into the microbial communities and functional bacteria in aerobic granular sludge and flocculent sludge in full-scale SBRs, which can provide microbes-informed optimisation of reactor operation for better nutrient removal. [Display omitted] • Higher richness and diversity of microbial community in granules than flocs. • Granules enriched more filamentous bacteria, nitrifying bacteria, and GAOs. • There were equivalent PAOs in granules and flocs. • Many putative PAOs might not contribute to P removal. • High abundance of GAOs such as 4.8% did not link with poor P removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • The fluctuation (±10-±30 %) of influent C/N ratio in MBBR was simulated. • The removal performance of NH 4 +-N and NO 3 −-N was almost unaffected. • The amount of cultivable NOB, aerobic DNB, and PAOs sharply decreased. • Candidatus Competibacter proliferated while Denitratisoma sharply decreased. • Endogenous denitrification might be responsible for nitrate removal. This study investigated the nutrient removal and microbial community succession in moving bed biofilm reactor under stable and three levels of influent carbon/nitrogen (C/N) ratio fluctuation (± 10%, ± 20%, and ± 30%). Under the conditions of influent C/N ratio fluctuation, the removal efficiency of COD and PO 4 3−-P decreased 4.7–6.4% and 3.7–12.9%, respectively, while the nitrogen removal was almost unaffected. A sharp decrease in the content of culturable functional bacteria related to nitrogen and phosphorus removal including nitrite-oxidizing bacteria (NOB), aerobic denitrifying bacteria (DNB), and polyphosphate-accumulating organisms (PAOs) from the carrier biofilm was observed. Sequencing analysis revealed that the abundance of Candidatus Competibacter increased 10.3–25.9% and became the dominant genus responsible for denitrification, potentially indicating that nitrate was removed via endogenous denitrification under the influent C/N ratio fluctuation. The above results will provide basic data for the nutrient removal in decentralized wastewater treatment under highly variable influent conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chlorella pyrenoidosa could effectively remove dissolved organic phosphorus (DOP). • The absorption of DOP mechanisms included direct and post-hydrolysis absorption. • DOP showed higher growth-promoting effect and increased microalgal biomass yield. • G-6-P promoted central carbon metabolism and biosynthetic pathways. • ATP increased photosynthetic activity but inhibited TCA cycle and purine metabolism. Microalgae-based biotechnology holds significant potential for addressing dual challenges of phosphorus removal and recovery from wastewater; however, the removal mechanism and metabolic adaptation of microalgae to dissolved organic phosphorus (DOP) are still unclear. This study investigated the removal mechanisms and metabolomic responses of the Chlorella pyrenoidosa to different DOP forms, including adenosine triphosphate (ATP), glucose-6-phosphate (G-6-P), and β-glycerophosphate (β-GP). The results showed C. pyrenoidosa could efficiently take up above 96% DOP through direct transport and post-hydrolysis pathways. The uptake of inorganic phosphorus (IP) followed pseudo first order kinetic model, while DOP followed pseudo second order kinetic model. Metabolite profiling revealed substantial alterations in central carbon metabolism depending on the DOP source. G-6-P upregulated glycolytic and TCA cycle intermediates, reflecting enhanced carbohydrates, amino acids and nucleotides biosynthesis. In contrast, ATP down-regulated carbohydrate and purine metabolism, inhibiting sustainable growth of microalgae. This study offers theoretical support for phosphorus-containing wastewater treatment using microalgae. [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]

[Display omitted] • Phosphate uptake on La-Fe-CNT film was a spontaneous-exothermic-multimechanism process. • Adsorption conditions were optimized by the response surface methodology. • The adsorption process was controlled by both intraparticle and surface film diffusion. • Adsorption mechanisms included ligand exchange, electrostatic attraction and surface complexation. Decreasing phosphate concentration in wastewater before discharge is crucial for preventing eutrophication. In this study, a novel La-Fe-CNT film was developed and its mechanism study for highly efficient phosphate adsorption was carried out. The morphology, thermal, structure and element analysis suggested that La and Fe hydroxide species were successfully fabricated on the CNT film and phosphate could be successfully adsorbed. The adsorption condition optimization of the La-Fe-CNT film was carried out by response surface methodology (RSM) with a Box–Behnken design (BBD). A low pH and low temperature were beneficial for the adsorption process, while the phosphate concentration showed little impact on phosphate uptake. It was indicated that pH = 4, temperature = 35.6 °C and phosphate concentration = 500 mg/L were the optimum adsorption conditions for La-Fe-CNT, with the optimized adsorption capacity of 137.8 mg/g, which was in good agreement with the actual value (140.3 mg/g). Thermodynamic analysis revealed that the q m of La-Fe-CNT film calculated from Langmuir model decreased from 164.9 mg/g to 121.7 mg/g from 30 to 80 °C, and the adsorption occurred through a spontaneous-exothermic-multimechanism process. This physicochemical process was controlled by both intraparticle and surface film diffusion. Adsorption experiments in presence of different ionic strengths and co-existing anions further confirmed the occurrence of inner-sphere and outer-sphere complexation during phosphate uptake. Overall, the La-Fe-CNT film showed ideal phosphate removal performance with high selectivity, indicating its potential for actual wastewater purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • The selective separation of V from BVS was achieved in the form of Pb 5 (VO 4) 3 OH. • Maximum Vanadium extraction efficiency reached 99.09% together with V 2 O 5 purity of 99.81%. • Removal of P, As and F was enhanced by double-salts precipitation of 2Na 3 AsO 4 ·NaF·19H 2 O, Na 3 PO 4 ·NaF·19H 2 O and NaSO 4 ·NaF. • The internal circulation system of auxiliary materials was established. Traditional approaches of vanadium recovery from Bayer vanadium sludge (BVS) discharged during the Bayer alumina production process affords large quantities of unusable solid waste and wastewater. In this study, a novel and sustainable process based on PbSO 4 precipitant was proposed to separate and recover vanadium from BVS. The results show that 99.09 % of vanadium was selectively extracted in the form of Pb 5 (VO 4) 3 OH with a Pb/V molar ratio of 1.7, NaOH concentration of 60 g/L at 70 °C for 30 min, whereas along with only 0.52 % of arsenate, 0.53 % phosphate, and 0.16 % of fluoride. To facilitate further recovery, the remaining phosphate, arsenate, and fluoride were simultaneously separated from NaOH solutions by evaporation crystallization and enriched into residue in the forms of 2Na 3 AsO 4 ·NaF·19H 2 O, 2Na 3 PO 4 ·NaF·19H 2 O, and NaSO 4 ·NaF. Subsequently, H 2 SO 4 leaching followed by (NH 4) 2 SO 3 leaching realized the maximum vanadium leaching efficiency of 99.15 % from Pb 5 (VO 4) 3 OH precipitate. Finally, the vanadium was deposited as (NH 4) 2 V 6 O 16 from leachate by adding stoichiometric (NH 4) 2 S 2 O 8 and then prepared the V 2 O 5 product with a purity of 99.81 %. Herein, the whole process realized the internal circulation of PbSO 4 , NaOH, water and solved the difficult treatment of solid waste and wastewater, which provides a new strategy for cleaner comprehensive utilization of BVS. [ABSTRACT FROM AUTHOR]

[Display omitted] • The introduced F-SBR had negligible effects on nutrient removal in S-SBR. • SVI 30 /SVI 5 of 86.9 % and SVI 30 of 45.8 mL/g reflected excellent sludge settleability. • The D av and D 90 of DAS particles were respectively less than 43 and 80 µm. • Shift work mode induced F/M rise and filamentous bacteria temporary proliferation. • The formation of DAS was attributed to applying shift work mode in the SNDPR system. Forming granular-like sludge in the Simultaneous Nitrification-Denitrification and Phosphorus Removal (SNDPR) process would promote nutrient removal and improve the sludge settleability. This study introduced the "shift work mode" into an SNDPR system, which featured that 50 % of sludge was temporarily transferred into and "rested" in a side-stream reactor a cyclic time rather than let it keep "working" in the mainstream SNDPR reactor. Results showed that 77.6 % of inorganic nitrogen and 80.6 % of orthophosphate were removed well even after the combination, which attributed to the co-work of Candidatus_Competibacter (10.1 %–29.0 %), nitrifiers, and phosphate accumulating organisms. The 30-min settled sludge volume and sludge volume index were 8 % and 45.8 mL/g, respectively, the sludge density was 1.045 g/mL, and cumulative 90 % of the particle diameter was less than 80 µm; these indicated the densified activated sludge was formed. After analyses, the increase in the food-to-microorganisms ratio and temporary enrichment of filamentous bacteria Thiothrix might be the causes. Such shift work mode promisingly serves as a simple and practical way to improve settleability and promote granulation. [ABSTRACT FROM AUTHOR]