Phosphorus Removal Technology Research Articles

Reutilization of post-adsorption lanthanum-loaded straw alleviates phosphorus pollution in rice-wheat system: Subsequent performance and underlying mechanisms

Adsorption technology for phosphorus (P) removal is considered promising and reutilization of post-adsorbent can contribute to promoting sustainable agricultural production. However, the long-lasting impact of the post-adsorbent on crop growth and P remains unclear. This study assessed the effects of P-adsorbed lanthanum-modified straw (La@straw-P) on the rice yield, P fractionation and associated water quality parameters. The findings indicated that, compared with traditional fertilizer regimes, La@straw-P expedited the P reduction in the flooding water achieving a rate of decline to the tertiary standard for surface water (0.20 mg/L) 3.8 times faster and enhanced increased the P harvest index by 17.00 %. Economic estimation proved the positive benefits of La@straw-P in planting-breeding combination system. Redundancy analysis (RDA) and co-occurrence network analysis (CONA) revealed that electrical conductivity (EC) and dissolved Fe played primary roles in regulating total P. Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and soil P fractions collectively demonstrated that the abundant adsorption sites on La@straw-P could facilitate the transformation of active P into moderately Ca-bound P. This study proposes a strategy for recycling P-adsorbed materials to mitigate agricultural non-point P pollution.

Modified rare earth waste composite material for simultaneous denitrification and recovery of phosphate in water

Nitrogen and phosphorus discharged into water bodies with sewage are the main causes of water eutrophication.Currently,the adsorption method is a cost-effective and efficient denitrification and phosphorus removal technology. In this study, waste polishing powder, manganese dioxide and sepiolite are used as raw materials, and a novel adsorbent of Sep-pp-MnO2 is prepared through co-precipitation and redox methods for simultaneous removal of ammonia nitrogen and recovery of phosphate in water.The physicochemical properties of the adsorbent are characterised, and the adsorption performances and denitrification and phosphorus removal mechanisms are determined. Results showed that,at a temperature of 25°C and pH of 8, the maximum removal of ammonia nitrogen reaches 11.47 mg/g, while the adsorption capacity for phosphates is 14.93 mg/g. Adsorption mechanisms indicated that the removal mechanism of phosphate is ligand exchange, while the removal mechanism of ammonia nitrogen involves electrostatic attraction and oxidation to nitrogen. Recycling experiments showed that after five desorption cycles, the material could achieve a removal of 4.7 mg/g for ammonia nitrogen, an adsorption capacity of 8.25 mg/g for phosphate and a phosphate recovery rate of 55 % after desorption with 0.1 M NaOH solution. Municipal wastewater validation experiments demonstrated that when the dosage of Sep-pp-MnO2 was 4 g/L,Treated water met the Class B requirements of the comprehensive emission standard for pollutants from urban sewage treatment plants in China (GB18918–2002). This study explores a new method for efficient simultaneous nitrogen and phosphorus removal in water and provides a feasible idea for alleviating the shortage of phosphate rock resources.

Advanced nitrogen and phosphorus removal from groundwater by a composite functional particle-ceramic membrane bioreactor

Nutrients are the main environment pollution issue in groundwater, while the efficient and sustainable membrane technology is the key to solving this problem. In this work, a composite functional particle-ceramic membrane bioreactor (CFP-CMR) was developed for advanced nitrogen and phosphorus removal from groundwater. Under the condition of moderate flux (5–15 L·m−2·h−1), CFP-CMR is able to sustain the preferable water purification performance (effluent: TP < 0.1 mg/L, NH3-N < 0.5 mg/L) for long-term stable operation (>100 days) via the synergy of membrane, adsorption, and microorganism. Composite functional particle could enrich and provide the carbon source for microorganism, as well as combine with the P in the water to form the crystals. The adsorption effect of composite functional particles in the early stage and the biological phosphorus removal in the later stage could synergistically improve the TP removal. Similarly, the CFP-CMR could ensure that the NH3-N in effluent reached the Chinese drinking water standard through the synergy of adsorption and microbial. However, the excessive gel layer with high C/N (i.e. Rhodobacter) on the ceramic membrane surface brought about the dissimilation reduction of nitrate to ammonium and affected the ammonia nitrogen removal. Besides, as the main membrane fouling, the biological gel layer could be effectively removed by hydraulic backwashing, so as to reduce the TMP and restore the permeability. Whereas, the re-startup after membrane cleaning clearly reduced the microbial and organics in the system, then weakened the nitrogen and phosphorus removal efficiency. In general, the findings of this work verify the reliability of CFP-CMR for the effective and sustainable operation of groundwater purification. The CFP-CMR combines the advantages of adsorption and biological processes, and is expected to become an effective technology for nitrogen and phosphorus removal.

Integrated control strategy for dual sludge ages in the high-concentration powder carrier bio-fluidized bed (HPB) technology: Enhancing municipal wastewater treatment efficiency

The high-concentration powder carrier bio-fluidized bed (HPB) technology is an emerging approach that enables on-site upgrading of wastewater treatment plants (WWTPs). HPB technology promotes the formation of biofilm sludge with micron-scale composite powder carriers as the core and suspended sludge mainly composed of flocs surrounding the biofilm sludge. This study proposed a novel integrated strategy for assessing and controlling the sludge ages in suspended/bio-film activated sludge supported by micron-scale composite powder carrier. Utilizing the cyclone unit and the corresponding theoretical model, the proposed strategy effectively addresses the sludge ages contradiction between denitrifying bacteria and polyphosphate-accumulating organisms (PAOs), thereby enhancing the efficiency of municipal wastewater treatment. The sludge age of the suspended (25 d) and bio-film (99 d) sludge, calculated using the model, contribute to the simultaneous removal of nitrogen and phosphorus. Meanwhile, the model further estimates distinct contributions of suspended and bio-film sludge to chemical oxygen demand (COD) and total nitrogen (TN), which are 55% and 42% for COD, 20% and 57% for TN of suspended sludge and bio-film sludge, respectively. This suggests that the contribution of suspended sludge and bio-film sludge to COD and TN removal efficiency can be determined and controlled by the operational conditions of the cyclone unit. Additionally, the simulation values for COD, ammonia nitrogen (NH4+-N), TN and total phosphorus (TP) closely align with the actual values of WWTPs over 70 days (p < 0.001) with the correlation coefficients (R2) of 0.9809, 0.9932, 0.9825, and 0.837, respectively. These results support the theoretical foundation of HPB technology for simultaneous nitrogen and phosphorus removal in sewage treatment plants. Therefore, this model serves as a valuable tool to guide the operation, design, and carrier addition in HPB technology implementation.

Sustainable phosphorus recycling: A review of advanced recovery methods with a focus on hydrothermal humification technology and potential phosphorus resources in China for this method

AbstractThe management of phosphorus (P) resources is facing dual challenges mediated by human activities: the scarcity of bioavailable P in soil and the disposal of massive undeveloped P resources in waste streams. In China, large amounts of P resources remain unexploited, including crop straw (0.9 Tg/year), pig manure (1.1 Tg/year), sludges (0.2 Tg/year), faeces (0.5 Tg/year) and outbreaking algae (0.48 Tg/year). Traditional P recovery technologies, including precipitation, acidulation and thermochemistry technology (PAT) and enhanced biological phosphorus removal technology (EBPR), have shown limitations in P recovery from these biomass waste streams. Hydrothermal humification technology (HTH) is a promising new technology, capable of converting typical waste streams into phosphate fertilizer for green and sustainable development. We estimate that the amount of available P that HTH could potentially extract from straw, macroalgae waste and sludge totals 0.46 Tg/year. Accordingly, the consistent development of HTH for the recycling of waste P in biomass will effectively improve China's P cycle and relieve the absence of phosphate rock sources and environment pollution.

Molecular transformation pathway and bioavailability of organic phosphorus in sewage sludge under vermicomposting

Phosphorus reclamation from sewage sludge is essential for sustainable phosphorus management, as large quantities of phosphorus afflux into wastewater treatment plants and are finally enriched in sewage sludge via phosphorus removal technologies. Meanwhile, vermicomposting is a cost-effective biotechnique for sludge stabilization. This work unveiled the molecular transformation pathway and bioavailability of organic phosphorus (OP) in sludge under vermicomposting with solution 31P NMR, FT-ICR MS and enzymatic hydrolysis assay. In conclusion, vermicomposting transformed OP in two stages. In stage I (day 0 to 14), macromolecule CHONP such as phospholipids, phosphoproteins and nucleic acid were decomposed into orthophosphate and high bioavailability OP including flavin mononucleotide, flavin mononucleotide hydrate and N6-isopentenyladenosine 5′-monophosphate under the action of earthworm intestinal flora. This resulted in the bioavailability of OP reaching a maximum of 13.58 mg/L on day 14. In stage II (day 14 to 28), the enzyme in vermicompost began to dominate the transformation of OP. Under the catalysis of phosphate, high bioavailability orthophosphate monoester was decomposed into orthophosphate. Nitrogen-containing aromatic OP polymerization produced humic acid-like OP under the catalysis of ligase. And phytic acid-like OP were produced under the catalysis of transferase. These led to the OP bioavailability decreasing to 5.60 mg/L on day 28. This work provides a new perspective on sludge phosphorus recovery and use.

Numerical simulation of a mechanical flocculation process with multi-chambers in series.

A mechanical flocculation system with multi-chambers in series is commonly used as the advanced phosphorus removal technology for wastewater treatment. This work aims to numerically investigate the inner states and overall performance of industrial-scale mechanical flocculators in series. This is based on our previously developed computational fluid dynamics (CFD) flocculation model which is extended to consider the key chemical reactions of phosphorus removal. The effects of the number of flocculation chambers, locations, and sizes of the flocculation chamber connection as well as operational combinations of impeller speeds are investigated. With a decreasing number of flocculation chambers, the main vortexes and chemical reactions are weakened, while the small flocs form. Both the phosphorus removal efficiency η and the average floc size dp reduce as the number of flocculation chambers decreases. The connection location of flocculation chambers directly determines the turbulent flow, thus influencing the key performance indicators. However, the phosphorus removal efficiency η and average particle size dp are little affected by the size of the flocculation chamber connection. As the impeller speeds in series gradually increase, the gradient of floc size distribution in each chamber is enlarged and the chemical reaction is enhanced over the working volume.

Redox environment inducing strategy for enhancing biological phosphorus removal in a full-scale municipal wastewater treatment plant

Phosphorus removal from wastewater is crucial for limiting water eutrophication. However, due to improper operating conditions, tremendous phosphorus removal chemicals addition or low C/N ratio in the influent, biological phosphorus removal (BPR) has been regarded as a difficult issue in real full-scale municipal wastewater treatment plants (WWTPs), especially in the membrane bioreactor (MBR) plants with long sludge retention time. Therefore, application of effective enhanced biological phosphorus removal (EBPR) technologies in WWTPs is of great significance to improve the BPR efficiency, reduce chemicals consumption and operating cost. Favorable redox environment, characterized by ORP is important for the growth and enrichment of phosphate-accumulating organisms (PAO), which is mainly responsible for BPR. In this study, a redox environment inducing strategy for EBPR was taken in a real full-scale MBR-WWTP (treatment capacity of 2 × 106 m3/d). The results indicated that the phosphorus release and uptake rate were rather low in the biochemical tank, which reflected the low phosphate-accumulating organisms (PAO) activity and poor BPR efficiency. This problem may be due to inappropriate redox environment, inhibition by phosphorus removal chemicals or low C/N in the influent. After EBPR, the contribution percentage of BPR increased by up to 18% and chemicals dosage reduced by up to 60%. Furthermore, the relative abundance of PAO (Dechloromonas, Thauera and OLB12) was significantly increased in anaerobic tank (4.62, 1.33 and 1.18%), in anoxic tank (4.85, 1.93 and 0.88%) and in oxic tank (5.17, 1.71 and 0.84%) for appropriate redox environment and relieved inhibition by less dosage of phosphorus removal chemicals. In addition, bacteria related to COD degradation and nitrogen removal were also enriched. The simultaneous enhancement of biological phosphorus removal, carbon removal and nitrogen removal was successfully realized in this research, which indicated that the strategy was effective in real large-scale WWTPs.

Performance enhancement and population structure of denitrifying phosphorus removal system over redox mediator at low temperature

The development of denitrifying polyphosphate accumulating organisms (DPAOs) presents a strategy to carbon competition between denitrifying bacteria and phosphorus removing bacteria. However, low temperature inhibits the rate of enzyme-catalyzed and substrate diffusion during denitrifying phosphorus removal (DPR). Therefore, the present study assessed the addition of NQS (100 μmol/L) for enhancing the removal of TP and TN in DPR reactors operated at alternating anaerobic and anoxic phases and different influent phosphate concentrations. The results showed that the removal efficiency of TP and TN in NQS-DPR system at 10 °C were 99.9% and 42.0%, respectively, which were 2.1 and 2.0 times higher than that of DPR system. Adding NQS significantly alleviated the increase of pH under anoxic condition and decreased the ORP value of the reactor, which in turn enhanced the PHAs accumulation process. The determination of functional genes (nirK, narG and phoD) showed that Dechloromonas, Lentimicrobium, and Terrimonas were the dominant functional bacteria in NQS-DPR system at 10 °C with the relative abundance of 3.09%, 2.99% and 2.28%, respectively. This study can provide valuable information for the effects of the addition of the redox mediator on denitrifying phosphorus removal technology.

Effect of granular matrix on functional flora in EBPR system

Enhanced biological phosphorus removal (EBPR) is a very mature phosphorus removal technology, but there is still a problem of unstable treatment effect in the operation of actual wastewater treatment plants, so the study on the effect of phosphorus removal performance still needs to be further studied. Because there are a lot of granular matrix in municipal wastewater, it occupies an important proportion in the total Chemical Oxygen Demand (COD) of municipal wastewater, and the fluctuation of granular matrix concentration is also related to the instability of phosphorus removal effect. Therefore, it is of practical guiding significance to further explore the influence of granular matrix on the functional bacteria community of phosphorus removal in the enhanced biological phosphorus removal system. The acetic acid was used as a carbon source to enrich and cultivate phosphorus accumulating bacteria. After the enrichment and the system was stable, soluble starch was added into the water to study the effects of granular matrix on phosphorus removal performance and functional bacteria community in EBPR system. The results showed that acetic acid was beneficial to the proliferation of phosphorus-accumulating bacteria in the enrichment stage, and the phosphate removal rate of the system could reach more than 99%. After the system is stabilized, granular matrix with different concentrations is added to the system in three stages, and the phosphate removal rate of the system gradually decreases. With the increasing of granular matrix concentration in the influent, the phosphorus removal performance of sludge decreased gradually, the maximum phosphorus release rate and maximum phosphorus uptake rate of sludge decreased, and the acetic acid utilization rate ΔP/ΔHAc value also decreased. Fluorescence in situ hybridization was used to measure the changes of functional bacteria in activated sludge under different conditions. With the increase of the concentration of soluble starch, the proportion of PAOs gradually decreased, and the proportion of GAOs gradually increased. Granular matrix exists in the internal of floc sludge and cannot be utilized by PAOs, which results in inhibition of the growth of PAOs and weakened activity. This indicates that the higher concentration of granular matrix will lead to a decrease in the proportion of PAOs in EBPR system, and then lead to a decrease in the phosphorus removal activity of activated sludge, and ultimately reduce the phosphorus removal effect of EBPR system.

A composite Fe–C/layered double oxides (Fe–C/LDO) carrier fabrication and application for enhanced removal of nitrate and phosphate from polluted water with a low carbon/nitrogen ratio

In this study, a multifunctional biofilm carrier (Fe–C/LDO) integrating Fe–C micro-electrolysis with Mg–Al layered double oxides (LDO) was developed and applied in a biofilter aimed to remove nitrogen and phosphorus simultaneously from slightly polluted water with a low carbon/nitrogen (C/N) ratio. Four types of carriers were prepared under different conditions and their performance in nitrate reduction and phosphorus removal were compared. Results showed that the composite Fe–C/LDO carrier prepared with polyethylene glycol as the pore-forming agent demonstrated the highest nitrate reduction rate and phosphorate adsorption capacity (2.09 mg PO43--P·g−1). A biofilter packed with the Fe–C/LDO carrier was investigated under heterotrophic conditions (C/N = 4.13) and complete autotrophic conditions (C/N = 0) during a long-term operation. Good removal of NH4+-N (96–98%), TN (92–96%) and PO43--P (50–58%) were achieved in the biofilter under both heterotrophic and autotrophic conditions. High throughput pyrosequencing analysis revealed that a large population of autotrophic denitrifying bacteria Thiobacillus and Thioalkalispira were enriched in the biofilm. Metagenomic analysis was performed to analyze functional genes related to nitrogen metabolism and carbon cycle, and it confirmed the presence of a whole denitrification and Calvin-Benson-Bassham carbon fixation pathway in biofilm. Finally, the possible mechanisms for nitrogen and phosphorus removal in the biofilter were proposed. The Fe–C/LDO carrier not only enriched abundant autotrophic denitrifying bacteria, but also provided numerous Fe–C galvanic cells for nitrate reduction through micro-electrolysis. In addition, the Mg–Al LDO in combination with iron hydroxides generated during micro-electrolysis may contribute greatly to phosphorus removal. Biofilter packed with the multifunctional Fe–C/LDO carrier could be a promising technology for simultaneous nitrogen and phosphorus removal from slightly polluted water.

Recovery of Phosphorus in Wastewater in the Form of Polyphosphates: A Review

As non-renewable resource, the recovery and utilization of phosphorus from wastewater is an enduring topic. Stimulated by the advances in research on polyphosphates (polyP) as well as the development of Enhanced Biological Phosphorus Removal (EBPR) technology to achieve the efficient accumulation of polyP via polyphosphate accumulating organisms (PAOs), a novel phosphorus removal strategy is considered with promising potential for application in real wastewater treatment processes. This review mainly focuses on the mechanism of phosphorus aggregation in the form of polyP during the phosphate removal process. Further discussion about the reuse of polyP with different chain lengths is provided herein so as to suggest possible application pathways for this biosynthetic product.

Correlation between phosphorus removal technologies and phosphorus speciation in sewage sludge: focus on iron-based P removal technologies

ABSTRACT Phosphorus recovery from sewage sludge as secondary raw materials or as a direct P-rich fertiliser is one of the top frontrunner solutions to tackle Phosphorus (P) scarcity and depletion. However, the efficiency of this P recovery process greatly depends on its phosphorus dissolution potential, which in return relies on the phosphorus speciation in the sewage sludge. This article investigates the potential correlation between P speciation in sewage sludge and the iron-based P removal technologies used in sewage treatment plants (STP) through an innovative sequential extraction method based on the SEDEX method that distinguishes quantitatively between ferrous bound phosphate and ferric bound phosphate. XRD and SEM-EDX were also used to characterise P and Fe species in the studied sludge qualitatively. Principal component analysis showed that the sludge characterised by P bound to ferric iron (as the dominant P fraction) are mostly correlated with sludge produced from the CPR process (chemical phosphorus removal) and primary sludge. Moreover, sludge with a non-negligible amount of P bound to ferrous iron were correlated with sludge from the mixed EBPR-CPR process (Enhanced Biological P Removal assisted with CPR). However, Vivianite was only found in CPR sludge with Fe/P molar ratio higher than 0.6.

Effects of coagulant morphology and chemical properties on soluble reactive phosphate removal in corn ethanol wastewater

As ethanol production continues to rise around the world, and wastewater discharge requirements for phosphorus become more stringent, it is important that phosphorus removal technologies are evaluated on ethanol wastewater streams. In this study, five coagulating agents with distinct characteristics were evaluated for their soluble reactive phosphate (SRP) removal performance on both a synthetic wastewater sample and a wastewater sample collected from a corn ethanol manufacturer. All coagulants demonstrated a positive correlation between coagulant dose and percent removal of SRP on both samples. Alum and ferric chloride produced the highest SRP removal efficiencies on both the ethanol and synthetic wastewater, indicating that prepolymerized, high-basicity coagulants (e.g., aluminum chlorohydrate, poly-aluminum ferric chloride) are less effective for SRP removal than nonpolymerized coagulants. The background matrix analysis combined with the pH studies revealed that the high alkalinity in the ethanol wastewater has a substantial inhibitory effect on SRP removal capacity that supersedes pH effects. These experimental results suggest that the Al-Al and Al-OH bonds in the heavily hydroxylated and polymerized structure of high-basicity coagulants are very rigid, which could prevent inner-sphere complexation and drive a less effective outer-sphere interaction, thus hindering SRP removal efficiency. PRACTITIONER POINTS: Five different coagulants are evaluated for reactive phosphate removal from wastewater. Alum and ferric chloride show higher removal efficiency than prepolymerized and high-basicity coagulants. Optimal removal pH increases with increasing coagulant basicity.

Nutrients removal by interactions between functional microorganisms in a continuous-flow two-sludge system (AAO-BCO): Effect of influent COD/N ratio

Denitrifying phosphorus removal (DPR) technology is one of the most effective approach to simultaneously realize nitrogen (N) and phosphorus (P) removal from low COD/N ratio wastewater. Identifying the interaction of denitrifying phosphate-accumulating organisms (DPAOs), denitrifying glycogen organisms (DGAOs) and denitrifying ordinary heterotrophic organisms (DOHOs) is critical for optimizing denitrification and anoxic P uptake efficiency in DPR processes. In this study, a novel DPR system of anaerobic anoxic oxic - biological contact oxidation (AAO-BCO) was employed to dispose actual sewage with various influent COD/N ratios (3.5–6.7). High efficiency of TIN (76.5%) and PO43−-P (94.4%) removal was observed when COD/N ratio was between 4.4 and 5.9. At the COD/N ratio of 5.7 ± 0.2, prominent DPR performance was verified by the superior DPR efficiency (88.7%) and anoxic phosphorus uptake capacity (PUADPAOs/ΔTIN = 1.84 mg/mg), which was further proved by the preponderance of DPAOs in C, N and P removal pathways. GAOs have a competitive advantage over PAOs for COD utilization at low COD/N ratio of 3.7 ± 0.2, which further limited the N removal efficiency. High proportion of N removal via DOHOs (21.2%) at the COD/N ratio of 6.5 ± 0.2 restrained the DPR performance, which should be attributed to the outcompete of DOHOs for NO3−. The nutrient removal mechanisms were explicated by stoichiometric calculation methodology to quantify the contribution of diverse functional microorganisms, contributing to improving the robustness of AAO-BCO system when facing the fluctuation of influent carbon source concentration.

Application of Iron and Sulfate-Modified Biochar in Phosphorus Removal from Water

The excessive discharge of phosphate into natural water has caused serious environmental problems. Adsorption is an efficient technology for phosphorus removal from water. In this study, a novel biochar modified by chitosan, ferrous sulfate, and sodium sulfide was synthesized and performed well in phosphorus adsorption. The results of batch experiments showed that the optimum synthesized composite could adsorb 49.32 mg·g-1 of phosphate at 298 K. Meanwhile, the simulation results showed better fitting with the pseudo-second-order model and Langmuir model. The adsorption rate was dominated by three-dimensional diffusion within the inner pores. The adsorption process was defined as physic/chemisorption, while the adsorption mechanism was concluded to be electrostatic adsorption, porous filling, surface chemical precipitation, hydrogen binding, and the ligand effect. This study showed that the composite is effective in phosphorus removal from water, and we anticipate that our research will offer guidelines for adsorbent design and reveal the adsorption mechanism.

Demonstration of ion exchange technology for phosphorus removal and recovery from municipal wastewater

• HAIX removed 90% of the PO 4 -P for 430 BV at 5 min EBCT. • HAIX removed 26% of the COD but it resulted in progressive fouling of the resin. • A regeneration with NaCl 5% is needed to maintain high adsorption capacity. • NaOH 2% can be used as regenerant solution for eight consecutive times. • Around 95% of the P was recovered from saturated NaOH as hydroxyapatite. Orthophosphate (PO 4 -P) removal and recovery from municipal wastewater were investigated in a 10 m 3 /day hybrid anion exchanger (HAIX) demonstration plant. To date, HAIX resins have been investigated for PO 4 -P removal at laboratory scale with promising results but there is a need to investigate the application of the technology at larger scale, over extended operation whilst establishing an efficient regenerant management solution. The HAIX removed an average of 6 mg PO 4 -P /L to > 0.3 mg PO 4 -P/L, within 430 bed volumes, with a capacity of 4.1 mg PO 4 -P/g resin. To manage the regenerant (NaOH 2%) efficiently, this was reused up to 8 times, reaching 785 mg PO 4 -P/L, but the adsorption capacity was compromised, and it decreased to 1.5 mg PO 4 -P/g resin. By adding calcium hydroxide to the saturated NaOH, 95% of the PO 4 -P was recovered as hydroxyapatite, and at the same time the regeneration effectiveness was re-established, as < 0.3 mg PO 4 -P/L was reached again in the effluent. The treated NaOH was reused as regenerant solution, ensuring high effluent quality of < 0.2 mg PO 4 -P/L. This study confirmed the capability of HAIX technology to remove and recover PO 4 -P from wastewater offering a solution which ensures both a high effluent quality and a circular economy approach.

The vertical recycled concrete aggregate filter for removal of phosphorus in wastewater

The irresponsible disposal of untreated wastewater into waters, soil and groundwater results in polluted water resources. Moreover, nutrients such as phosphorus have become culprits of concern in accelerating eutrophication. Besides, this issue could cause water poisoning and the degradation of recreational opportunities. Therefore, for justifying this problem, it is important to understand the quantity of phosphorus (P) flows by using recycled concrete aggregate (RCA) as filter materials. RCA used as a filter system has emerged as an alternative technology for phosphorus removal. This can overcome the problem of construction site waste by converting the waste into valuable products. Thus, this study aims to investigate the physical and chemical characteristics of RCA that influenced adsorption of P and the percentage of phosphorus removal from synthetic wastewater by using two different sizes of RCA. A total of five vertical recycled concrete aggregate filter was designed. The samples taken from influent and effluent were tested once a week and analyzed to determine pH and percentage removal phosphorus. RCA was analyzed using Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) testing to determine chemical composition. The results show that RCA primarily contained aluminium, calcium, and magnesium that could enhanced the phosphorus adsorption. The RCA with size 5 to 10 mm is shown to have high potential to remove phosphorus up to 99.57%. The higher the size of RCA, the higher percentage of phosphorus removal. In conclusion, RCA has the potential to remove phosphorus from wastewater.

Design, operation and technology configurations for enhanced biological phosphorus removal (EBPR) process: a review

Phosphorus as a fundamental element for growth and metabolism of living organisms, yet problematic to water quality, is an irreplaceable component. Application of enhanced biological phosphorus removal (EBPR) technology in wastewater treatment plants offers phosphorus removal and recovery in addition to potential eutrophication prevention. This process is dependable on enrichment of phosphorus accumulating organisms in activated sludge to accumulate great amount of poly-phosphate inside their cell interior for enhancement of phosphorus removal. Yet, inadequate removal performance in pilot and full-scale systems, rises the need for optimization in operation and design of applicable configuration. In addition to applying advancement strategies to minimize the growth of undesirable microorganisms through cost effective phosphorus removal along with potential P-recovery and sustainability. Preceding research has certainly advanced the insight on this area of investigation. Notwithstanding, there are still numerous unresolved issues to be undertaken. This comprehensive review paper aims to revisit the current knowledge and fundamental understanding on microbiology and biochemical transformations in EBPR process. In view of application and structure, EBPR design and operation considerations along with process configurations is critically reviewed. This comprehensive review hopes to touch on the critical points of operation to help in understanding the overall EBPR process and to farther provide insights on future work onto EBPR process developments.

Enhancement of anoxic phosphorus uptake of denitrifying phosphorus removal process by biomass adaption

Economical and efficient phosphorus (PO4-P) removal technologies with low oxygen and organic carbon demand are needed to avoid eutrophication and reduce wastewater treatment costs. A sequencing batch reactor (SBR) treating synthetic wastewater with similar characteristics to real domestic wastewater using peptone and meat extract as carbon sources and nitrate as terminal electron acceptor was set up to enhance anoxic PO4-P uptake of denitrifying phosphorus removal process. In the anaerobic/anoxic/oxic SBR, activated sludge inoculum was gradually adapted to prolonged anoxic and shortened aerobic phase durations of 3.5 h and 1 h, respectively. During biomass adaption, anoxic PO4-P uptake fraction from total PO4-P (anoxic + aerobic) uptake was enhanced from 70.5 to 90.4%. SBR long-term operation results showed that dosed nitrate loading and aeration phase duration affected PO4-P and total nitrogen (TN) removal. The highest PO4-P removal of 22.4 mg PO4-P g−1 mixed liquor suspended solids (MLSS) and average TN removal efficiency of 74.2% were achieved with 1-h aeration duration. The best dosed nitrate loading ranges for effective PO4-P and TN removal were 11.3–13.7 and 11.1–19.4 mg N g−1 MLSS d−1, respectively. Chemical oxygen demand and dissolved organic carbon removal efficiencies remained unaffected by changes in operating conditions with average values up to 96.3% and 98.0%, respectively. Pyrosequencing results demonstrated that during biomass adaption microbial community changed and adapted sludge probably contained some novel denitrifying phosphorus accumulating organisms. Therefore, this research shows that biomass adaption enabled to achieve efficient denitrifying phosphorus removal without acetate/propionate addition in the conditions similar to real domestic wastewater.