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Phosphorus (P) removal is a significant issue in wastewater treatment. This study applies Fe-Al composite coagulant to the advanced treatment of different P forms in biological effluent. For 90% total P removal, the dosage of FeCl 3 -AlCl 3 composite coagulant reduces by 27.19% and 43.28% than FeCl 3 and AlCl 3 only, respectively. Changes in effluent P forms could explain the phenomenon of composite coagulant dosage reduction. The suspended P in the effluent of composite coagulant is easier removed by precipitation than single coagulant. In this study, the hydrolysis speciations of Fe 3+ , Fe 2+ , and Al 3+ at a pH range are calculated by Visual MINTEQ. Changes in the morphology of metal hydroxides correlate with P removal at pH 4–9. Besides, analyses of scanning electron microscope (SEM), Fourier transformed infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) are performed on the coagulation precipitations. Fe 2+ reacts directly with P to form flocs of Fe 3 (PO 4 ) 2 , and Al 2 (SO 4 ) 3 assists in the sedimentation of the small-volume flocs. Al 13 is a significant hydrolysis product of Al 3+ , and Fe and P would substitute for the peripheral Al VI of the Al 13 structure to form stable Fe–O–Al covalent bonds.

Mathematical modelling was used to investigate the possibility to use membrane aerated biofilm reactors (MABRs) in a largely anoxic suspended growth bioreactor to produce the nitrate-nitrogen required for heterotrophic denitrification and the growth of denitrifying phosphorus accumulating organisms (DPAOs). The results indicate that such a process can be used to achieve a variety of process objectives. The capture of influent biodegradable organic matter while also achieving significant total inorganic nitrogen (TIN) removal can be achieved with or without use of primary treatment by operation at a relatively short suspended growth solids residence time (SRT). Low effluent TIN concentrations can also be achieved, irrespective of the influent wastewater chemical oxygen demand (COD)/total nitrogen (TN) ratio, with somewhat larger suspended growth SRT. Biological phosphorus and nitrogen removal can also be effectively achieved. Further experimental work is needed to confirm these modelling results.

Members of the genus Tetrasphaera are considered to be putative polyphosphate accumulating organisms (PAOs) in enhanced biological phosphorus removal (EBPR) from wastewater. Although abundant in Danish full-scale wastewater EBPR plants, how similar their ecophysiology is to ‘ Candidatus Accumulibacter phosphatis’ is unclear, although they may occupy different ecological niches in EBPR communities. The genomes of four Tetrasphaera isolates ( T. australiensis , T. japonica , T. elongata and T. jenkinsii ) were sequenced and annotated, and the data used to construct metabolic models. These models incorporate central aspects of carbon and phosphorus metabolism critical to understanding their behavior under the alternating anaerobic/aerobic conditions encountered in EBPR systems. Key features of these metabolic pathways were investigated in pure cultures, although poor growth limited their analyses to T. japonica and T. elongata . Based on the models, we propose that under anaerobic conditions the Tetrasphaera -related PAOs take up glucose and ferment this to succinate and other components. They also synthesize glycogen as a storage polymer, using energy generated from the degradation of stored polyphosphate and substrate fermentation. During the aerobic phase, the stored glycogen is catabolized to provide energy for growth and to replenish the intracellular polyphosphate reserves needed for subsequent anaerobic metabolism. They are also able to denitrify. This physiology is markedly different to that displayed by ‘ Candidatus Accumulibacter phosphatis’, and reveals Tetrasphaera populations to be unusual and physiologically versatile PAOs carrying out denitrification, fermentation and polyphosphate accumulation.

Enhanced biological phosphorus removal (EBPR) process is one of the most economical and sustainable methods for phosphorus removal from wastewater. However, the performance of EBPR can be affected by available carbon sources types in the wastewater that may induce different functional microbial communities in the process. Glycogen accumulating organisms (GAOs) and polyphosphate accumulating organisms (PAOs) are commonly found by coexisting in the EBPR process. Predominance of GAO population may lead to EBPR failure due to the competition on carbon source with PAO without contributing phosphorus removal. Carbon sources indeed play an important role in alteration of PAOs and GAOs in EBPR processes. Various types of carbon sources have been investigated for EBPR performance. Certain carbon sources tend to enrich specific groups of GAOs and/or PAOs. This review summarizes the types of carbon sources applied in EBPR systems and highlights the roles of these carbon sources in PAO and GAO competition. Both single (e.g., acetate, propionate, glucose, ethanol, and amino acid) and complex carbon sources (e.g., yeast extract, peptone, and mixed carbon sources) are discussed in this review. Meanwhile, the environmental friendly and economical carbon sources that are derived from waste materials, such as crude glycerol and wasted sludge, are also discussed and compared.

This review summarizes the main species of polyphosphate accumulating organisms (PAOs) and algae, illustrates their pathways and key enzymes, discusses biological phosphorous (P) recovery from dilute waters, and identifies research avenues to encourage adoption and implementation. Phylogenic analysis indicates that the Proteobacteria phylum plays an important role in enhanced biological phosphorus removal (EBPR). The use of meta-transcriptome analysis and single cell-based techniques to help overcome the challenges associated with non-PAO competition was discussed. For algae capable of luxury phosphorus uptake, fundamental research is needed to illustrate the phosphorus regulation process and key proteins involved. Emerging technologies and processes have great potential to further advance phosphorus recovery, including combined PAO/algae reactors, bioelectrochemical systems, and biosorption by phosphorus binding proteins. As the paradigm shifts toward holistic resource recovery, research is needed to explore P+ recovery with other resources (e.g., metals from sludge), using a combination of biological and chemical approaches.

The responses of total nitrogen (TN) and total phosphorus (TP) removal performance and microbial community to 0–1.2 g/L Fe3O4@SiO2 nanoparticles (NPs) in sequencing batch reactors were investigated. Results showed that an appropriate dose of Fe3O4@SiO2 NPs (0.3 g/L) could promote the removal efficiency of TN and TP. High-throughput sequencing results indicated that microbial richness increased, whereas microbial diversity did not vary upon exposure to 0.1–1.2 g/L Fe3O4@SiO2 NPs. The relative abundances of Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria increased from 11.75%, 3.52%, and 6.77%, respectively, at 0 g/L Fe3O4@SiO2 to 27.05%, 7.21%, and 14.77%, respectively, upon exposure to 0.3 g/L Fe3O4@SiO2. At the genus level, 0.3 g/L Fe3O4@SiO2 NPs enriched norank_f_Nitrosomonadaceae, norank_f_Xanthomonadaceae, Amaricoccus, and Shinella. Real-time quantitative polymerase chain reaction results suggested that the gene copy number of ammonium-oxidizing, nitrite-oxidizing, and denitrifying bacteria population remarkably increased, whereas the number of phosphorus-accumulating organisms slightly increased under long-term exposure to 0.3 g/L Fe3O4@SiO2 NPs. Energy-dispersive spectrum analysis showed that the phosphorus content was higher at 0.3 g/L Fe3O4@SiO2 than at 0 g/L Fe3O4@SiO2. Nitrogen removal primarily occurred through a biological mechanism, while most phosphorus in wastewater may be removed by the combination of physicochemical and biological methods.

It was necessary to research an efficient treatment process suitable for township domestic wastewater. In this paper, the performance of the cyclic activated sludge system (CASS) system for simultaneous carbon (C), nitrogen (N) and phosphorus (P) removal was investigated by changing the operation cycle of the CASS reactor. Four operating conditions were set up, T1, T2, T3 and T4, with cycle times of 6, 8, 12 and 8 h (with carbon source), respectively. The results showed that the CASS system had good simultaneous removal of C, N and P. The highest removal rates of COD, TN, NH4+ -N and TP were 87.69, 72.99, 98.60 and 98.38%, respectively, at a cycle time of 8 h. The TN removal rate could be increased to 82.51% after the addition of carbon source. Microbial community analysis showed that Proteobacteria, Bacteroidetes and Candidatus Saccharibacteria were the main phylum-level bacteria. Their presence facilitated the effectiveness of the CASS process for nitrogen removal and phosphorus removal. Functional analysis of genes revealed that the abundance values of genes associated with C, N and P metabolism were higher when the treatment was effective.

Pollution caused by N and P is a significant contributor to water eutrophication. While traditional biological treatment processes can remove some N and P elements from water, the effluent quality often fails to meet the stringent requirements of sensitive areas. The autotrophic denitrification’s simultaneous nitrogen and phosphorus removal pro-cess, known for its low operating cost and minimal sludge production, has garnered considerable attention from researchers. In this study, natural pyrite was used for the removal of nitrogen and phosphorus in a denitrification system, and the underlying mechanisms were elucidated. The results indicate that the N and P removal efficiency was influenced by empty bed contact time (EBCT) and the pH value. The highest NO3−-N removal rate of 90.24% was achieved at an EBCT of 8 h, while the PO43−-P removal rate reached 81.58% at an EBCT of 12 h. The addition of a carbon source enhanced the synergistic autotrophic/heterotrophic denitrification, significantly improving phosphorus removal with an increasing C/N ratio. Microbial characteristics analysis revealed that, at the phylum level, Chlorobiota, Bacteroidota, and Chloroflexota played a crucial role in heterotrophic autotrophic denitrification. At the genus level, Thauera, Aridibacter, and Gemmatimonas were key players in heterotrophic denitrification, while Thiobacillus, Rhodoplanes, and Geobacter were associated with autotrophic denitrification.

Controlling dissolved phosphorus (P) losses to surface waters is challenging as most conservation practices are only effective at preventing particulate P losses. As a result, P removal structures were developed to filter dissolved P from drainage water before reaching a water body. While many P removal structures with different P sorption materials (PSMs) have been constructed over the past two decades, there remains a need to evaluate their performances and compare on a normalized basis. The purpose of this review was to compile performance data of pilot and field-scale P removal structures and present techniques for normalization and comparison. Over 40 studies were normalized by expressing cumulative P removal as a function of cumulative P loading to the contained PSM. Results were further analyzed as a function of retention time (RT), inflow P concentration, and type of PSM. Structures treating wastewater were generally more efficient than non-point drainage water due to higher RT and inflow P concentrations. For Ca-rich PSMs, including slag, increased RT allowed for greater P removal. Among structures with low RT and inflow P concentrations common to non-point drainage, Fe-based materials had an overall higher cumulative removal efficiency compared to non-slag and slag materials.

Excess phosphorus in water supplies causes eutrophication, which degrades water quality. Hence, the efficient removal of phosphorus from wastewater represents a highly desirable process. Here, we evaluated the effect of sulfate concentration on enhanced biological phosphorus removal (EBPR), in which phosphorus is typically removed under anaerobic-oxic cycles, with sulfate reduction the predominant process in the anaerobic phase. Two sequencing batch EBPR reactors operated under high- (SBR-H) vs. low-sulfate (SBR-L) concentrations for 189 days and under three periods, i.e., start-up, sufficient acetate, and limited acetate. Under acetate-rich conditions, phosphorus removal efficiency was > 90% for both reactors; however, under acetate-limited conditions, only 34% and 91.3% of the phosphorus were removed for the SBR-L and the SBR-H, respectively. Metagenomic sequencing of the reactors showed that the relative abundance of the polyphosphate-accumulating and sulfur-reducing bacteria (SRB) was higher in the SBR-H, consistent with its higher phosphorus removal activity. Ten high-quality metagenome-assembled genomes, including one closely related to the genus Thiothrix disciformis (99.81% average amino acid identity), were recovered and predicted to simultaneously metabolize phosphorus and sulfur by the presence of phosphorus (ppk, ppx, pst, and pit) and sulfur (sul, sox, dsr, sqr, apr, cys, and sat) metabolism marker genes. The omics-based analysis provided a holistic view of the microbial ecosystem in the EBPR process and revealed that SRB and Thiothrix play key roles in the presence of high sulfate.Key points• We observed high phosphorus-removal efficiency in high-sulfate EBPR.• Metagenome-based analysis revealed sulfate-related metabolic mechanisms in EBPR.• SRB and PAOs showed interrelationships in the EBPR–sulfur systems.