Ammonia Nitrogen Removal Efficiency Research Articles

Nitrogen removal and performance deterioration in digested effluent treatment by partial nitrification-anammox (PNA) process based on aeration sedimentation integrated microaerobic reactor (ASIMR)

The existing microaerobic reactors for PN/A process have the drawbacks of complex structure and hard to scale-up in full scale application. Aiming at these problems, we have designed new aeration sedimentation integrated microaerobic reactor (ASIMR). The feasibility of ASIMR for PN/A processes and the optimal HRT were explored by gradually reducing the hydraulic retention time (HRT). When the HRT was 4.45 h and the NLR was 3.98 kg·(m3·d)-1, ASIMR achieved the highest nitrogen removal performance, with the ammonia nitrogen removal efficiency (ARE) and total nitrogen removal efficiency (NRE) of 90.5 % and 79.2 %, respectively, and the total nitrogen removal rate (NRR) could reach 3.15 kg·(m3·d)-1. When HRT decreased to 3.60 h with the NLR of 4.76 kg·(m3·d)-1, the performance deterioration was observed, with ARE and NRE decreasing to 35.9 % and 12.4 %, and NRR decreasing to 0.59 kg·(m3·d)-1. The main reasons for the decrease in nitrogen removal performance were overhigh hydraulic load in the sedimentation zone which led to the loss of nitrifying sludge. The loss of nitrifying sludge in turn reduced the efficiency of ammonia nitrogen removal resulting in the accumulation of free ammonia (FA) which inhibited the activity of nitrogen removal functional bacteria. Although reactor performance deteriorated at too low HRT, when the HRT was much than 4.45 h, ASIMR could achieve a good performance for nitrogen removal owe to the combined action of reactor design, enriched nitrified and anammox sludge as inoculum, and dissolved oxygen control. Except good nitrogen removal performance, ASIMR has another advantage, such as simple structure, low cost for manufacture, and more suitable for engineering scale-up in full scale application.

Schwarzite-based 3D-printed carriers for enhanced performance of sequencing batch biofilm reactor (SBBR) for wastewater treatment

The energy-efficient, green, and sustainable wastewater treatment using biofilm reactors is gaining a lot of attention. The efficiency of biofilm-based reactors (e.g., sequencing batch biofilm reactor (SBBR) and moving bed biofilm reactor (MBBR), etc.) can be further improved with the help of strong, highly active, and functionally engineered carriers. Here, Schwarzite-based 3D-printed biocarriers were prepared to obtain optimum mechanical properties and enhanced organics and nutrient removal efficiencies. The optimized carrier (L2) possesses the highest porosity (∼75%) and specific modulus of resilience and lowest bulk density among the other prepared structures (i.e., L1, L3, and L4). High porosity and specific surface area of the carriers promote enhanced growth of biomass with a total of 0.3 g biomass/carrier. The optimized biocarrier showed ∼95% chemical oxygen demand and ∼84% ammonium nitrogen removal efficiencies, which were attributed to its high specific surface area and porosity. The performance of SBBR with 3D-printed biofilm carriers having only a 15% fill ratio was compared and found better than the conventional K2 carriers used with a filling ratio of 50%. The high mechanical stability and specific surface area of the L2 biocarrier make it feasible to be used as a biofilm carrier, which may drastically reduce the number of carriers thereby directly reducing the cost.

Copper oxide nanoparticles influence on the performance of sequencing batch reactor and the transfer of antibiotic resistance genes by regulating bacterial quorum sensing system

The environmental pollution caused by copper oxide nanoparticles (CuO NPs) has attracted widespread attention. In this study, microbial community, key metabolic pathways and quorum sensing (QS) were investigated to reveal the impact of copper oxide nanoparticles (CuO NPs) on the performance of sequencing batch reactor (SBR) and the transfer of antibiotic resistance genes (ARGs). Results showed that under CuO NPs impact, the removal efficiency of COD, ammonium nitrogen (NH4+-N) and total nitrogen (TN) was stable at around 90%, 96% and 60%, respectively. However, removal efficiency of total phosphorus (TP) was reduced to below 60% under 0.1 mg/L and 1 mg/L CuO NPs exposure. Microbial community analysis showed CuO NPs was advantageous to the growth of key functional bacterial phyla Bacteroidetes, Proteobacteria and Patescibacteria. The relative abundance of Candidatus Accumulibacter genus and ppX gene were decreased, which then lower the TP removal efficiency. Besides, CuO NPs might trigger QS system, affecting Candidatus Accumulibacter, Aeromonas genus and ppX gene, and then regulated the removal of TP in the SBR system. The co-occurrence network analysis revealed a correlation among core ARGs, signaling molecule, QS-related microbial community and ARGs’ hosts, suggesting that the spread of ARGs might be driven by QS system under selective pressure of CuO NP. These findings could reveal the effect of CuO NPs on the performance of activated sludge system and provides new ideas for ARGs control through regulating the QS system.

Nutrient removal performance from agricultural drainage by strengthening ecological ditches in hilly areas

Agricultural drainage from catchment greatly impacts water quality in the hilly area due to high nitrogen concentrations in the central basin of Sichuan Province, China. The original ecological ditches have proven effective in removing associated nutrient loads, but their nitrogen removal efficiency is limited by the elevated nitrogen levels of overland flow and subsurface flow. Field experiments were conducted to optimize the drainage network to enhance the performance of ecological ditches and enhance nitrogen removal efficiency in hilly regions. The results suggested that ecologically permeable dam ditches exhibited superior total nitrogen (TN) and total phosphorus (TP) removal efficiencies compared to single dams, multiple dams, and ecological intercept dams. Specifically, in single, multiple, and ecological intercept dams, TN removal was 20.2 %, 12.7 %, and 2.5 % higher, respectively, while TP removal was 18.2 %, 10.3 %, and 3.7 % higher, respectively. The TN removal efficiency by the Hydrocotyle verticillate and Iris pseudacorus L. ditch was 15.8 % and 2.3 % higher than that of the Myriophyllum verticillatum L. and Hydrocotyle verticillata and Hydrocotyle verticillata and Thalia dealbata Fraser, respectively. The TP removal efficiency in Hydrocotyle verticillata and Thalia dealbata Fraser ditch was 11.4 % and 3.5 % higher than that in Myriophyllum verticillatum L. and Hydrocotyle verticillata and Hydrocotyle verticillate and Iris pseudacorus L., respectively. The soil bed ditch demonstrated superior TN and TP removal efficiencies, with rates of 15.2 % and 11.3 %, respectively, compared to the pebble bed and mudstone bed (2.9 % and 3.4 %, respectively). Therefore, the original ecological ditch was reinforced through a combination of fine-textured soil substrates, native emergent plants with large biomass and ecologically permeable dams to enhance the removal efficiencies of TN and TP in agricultural drainage. Following reinforcement and evaluation in 2020, the removal efficiencies of TN, TP, ammonia nitrogen (AN) and nitrate nitrogen (NN) in the strengthened ecological ditches increased to 58.1 %, 56.5 %, 56.8 % and 54.2 %, respectively. In this study, a scientific foundation for enhancing the efficacy of ecological ditches in mitigating nonpoint source pollution from agricultural drainage in mountainous and hilly regions of subtropical and developing countries is established.

A pilot-scale SNAD-MBBR process for treating anaerobic digester liquor of swine wastewater: performance and microbial community.

In this pilot-scale study, simultaneous partial nitrification, anammox, and denitrification (SNAD) process was achieved successfully in a moving bed biofilm reactor (MBBR) for treating anaerobic digester liquor of swine wastewater. After 95days of operation, when the total nitrogen loading rate of SNAD-MBBR process was 1.09kg TN/m3/day, the total nitrogen removal rate could reach 0.87kg TN/m3/day, and the removal efficiencies of ammonium and total nitrogen were 92.0% and 79.7%, respectively. The optimum pH and temperature for SNAD-MBBR process were 8.5 and 35°C, respectively, and the optimum dissolved oxygen for SNAD1 and SNAD2 were 0.30 and 0.07mg/L, respectively. The 16S rRNA sequencing suggested that Candidatus Kuenenia, Candidatus Brocadia, Nitrosomonas, and Denitratisoma were the dominant nitrogen removal bacteria. Some of the co-existing bacteria (Truepera, Limnobacter, and Anaerolineaceae uncultured) promoted ammonium oxidation and guaranteed the growth of the anammox bacteria under adverse environmental conditions. Overall, this study demonstrated that the SNAD-MBBR process would be an energy-saving and cost-effective method for the removal of nitrogen from swine wastewater and provided important process parameters for stable operation of the full-scale SNAD process.

Ammonia Nitrogen Removal by Gas–Liquid Discharge Plasma: Investigating the Voltage Effect and Plasma Action Mechanisms

Atmospheric pressure gas–liquid discharge plasma has garnered considerable attention for its efficacy in wastewater contaminant removal. This study utilized atmospheric oxygen gas–liquid discharge plasma for the treatment of ammonia nitrogen wastewater. The effect of applied voltage on the treatment of ammonia nitrogen wastewater by gas–liquid discharge plasma was discussed, and the potential reaction mechanism was elucidated. As the applied voltage increased from 9 kV to 17 kV, the ammonia nitrogen removal efficiency rose from 49.45% to 99.04%, with an N2 selectivity of 87.72%. The mechanism of ammonia nitrogen degradation by gas–liquid discharge plasma under different applied voltages was deduced through electrical characteristic analysis, emission spectrum diagnosis, and further measurement of the concentration of active species in the gas–liquid two-phase system. The degradation of ammonia nitrogen by gas–liquid discharge plasma primarily relies on the generation of active species in the liquid phase after plasma–gas interactions, rather than direct plasma effects. Increasing the applied voltage leads to changes in discharge morphology, higher energy input, elevated electron excitation temperatures, enhanced collisions, a decrease in plasma electron density, and an increase in rotational temperatures. The change in the plasma state enhances the gas–liquid transfer process and increases the concentration of H2O2, O3, and, ⋅OH in the liquid phase. Ultimately, the efficient removal of ammonia nitrogen from wastewater is achieved.

Nitrogen removal and nitrous oxide emission in the partial nitritation/anammox process at different reflux ratios

The partial nitritation/anammox (PN/A) process has been widely used in wastewater treatment owing to its notable advantages, including a low aeration rate and the non-requirement of an additional carbon source. In practical implementation, nitrite accumulation affects the nitrogen-removal efficiency and the amount of N2O released during the PN/A process. By implementing wastewater reflux, the nitrite concentration can be decreased, thereby achieving a balance between the nitrogen-removal efficiency and N2O release. This study conducted the CANON process with varying reflux ratios of 0 to 300 % and ~300 mg/L ammonium in the influent. The highest removal efficiency of ammonium and total nitrogen (98.2 ± 0.8 and 77.8 ± 2.3 %, respectively) could be achieved at a reflux ratio of 200 %. Further, a reflux ratio of 200 % led to the lowest N2O emission factor (2.21 %), with a 31.74 % reduction in N2O emission compared to the process without refluxing. Additionally, the reactor at a reflux ratio of 200 % presented the highest relative abundance of anaerobic ammonium-oxidizing bacteria (30.98 %) and the lowest proportion of ammonium-oxidizing bacteria (9.57 %). This study aimed to elucidate the impact of the reflux ratio on the nitrogen-removal efficiency of the CANON process and to theoretically explain the influence of different reflux ratios on N2O release. These findings provide a theoretical framework for enhancing the nitrogen-removal efficiency and mitigating carbon emissions in practical applications of the CANON process.

The removal of ammonia-nitrogen from aquaculture water based on cavitation effect of ultrasonic vibration

This paper mainly studies the mechanism and efficiency of ammonia-nitrogen removal from circulating sewage in closed fish tank system. According to some factors affecting the removal efficiency (ultrasonic power, ultrasonic time and water oxygen concentration). Simulated circulating sewage mixed with oxygen through a venturi tube and then entered a closed experiment box for ultrasonic experiments. Finally, the removal efficiency was determined by Knott's reagent photometry. In the experiment, the PH value of the simulated sewage was 7.5, the indoor water temperature was 20 °C, and the free ammonia was selected as 0.02 mg/L (total ammonia-nitrogen was 1.6 mg/L) according to the standard. The experiment found that when the ultrasonic power is 400 W, the action time is 2 h, and the oxygen concentration of water is 23.8 mg/L, the efficiency of removing ammonia-nitrogen in water is about 65 %. When applied on fishing vessels, increasing the power can increase the removal efficiency.

A semi-continuous efficient strategy for removing phosphorus and nitrogen from eel aquaculture wastewater using the self-flocculating microalga Desmodesmus sp. PW1

The phosphorus content in eel aquaculture wastewater exceeds the discharge standard, and the amount of wastewater discharged is substantial. Therefore, there is an urgent need to explore an economical and efficient method of treating aquaculture wastewater. This study explored the use of Desmodesmus sp. PW1, a type of microalgae, to treat eel aquaculture wastewater. By optimizing the conditions, Desmodesmus sp. PW1 achieved a total phosphorus (TP) removal efficiency of 92.3%, as well as total nitrogen (TN) and ammonia nitrogen (NH4+-N) removal efficiency of 99%, using a photoperiod of 24:0, a temperature of 25 °C, and an inoculation amount of 15%. Furthermore, Desmodesmus sp. PW1 demonstrated a high self-flocculating efficiency (>90%) within 100 min of settling, which facilitated biomass recovery. Subsequently, a semi-continuous treatment process mode was established with a sewage renewal rate of 90%. The results showed that after four rounds of sewage renewal operations, the microalgae biomass in the sewage treatment system could be maintained between 160.0 and 220.0 mg/L, and the average removal rate of TP was 0.13 mg/(L * h). The lipid content of algae cells collected in the semi-continuous treatment system for eel aquaculture wastewater was as high as 36.5%, and the biodiesel properties met the biodiesel standards authorized by Europe and the United States. Overall, this study provides an economical and effective strategy for converting wastewater into high-value microalgae products.

Responses of the microbial community and the production of extracellular polymeric substances to sulfamethazine shocks in a novel two-stage biological contact oxidation system.

The biological contact oxidation reactor is an effective technology for the treatment of antibiotic wastewater, but there has been little research investigating its performance on the sulfamethazine wastewater treatment. In this study, a novel two-stage biological contact oxidation reactor was used for the first time to explore the impact of sulfamethazine (SMZ) on the performance, microbial community, extracellular polymeric substances (EPS), and antibiotic-resistant genes (ARGs). The chemical oxygen demand (COD) and ammonia nitrogen (-N) removal efficiencies kept stable at 86.93% and 83.97% with 0.1-1 mg/L SMZ addition and were inhibited at 3 mg/L SMZ. The presence of SMZ could affect the production and chemical composition of EPS in the biofilm, especially for the pronounced increase in TB-PN yield in response against the threat of SMZ. Metagenomics sequencing demonstrated that SMZ could impact on the microbial community, a high abundance of Candidatus_Promineofilum, unclassified_c__Anaerolineae, and unclassified_c__Betaproteobacteria were positively correlated to SMZ, especially for Candidatus_Promineofilum. Candidatus_Promineofilum not only had the ability of EPS secretion, but also was significantly associated with the primary SMZ resistance genes of sul1 and sul2, which developed resistance against SMZ pressure through the mechanism of targeted gene changes, further provided a useful and easy-implement technology for sulfamethazine wastewater treatment.

Effects of humic acid on nutrient removal efficiency of aquatic duckweed (Lemna minor) and both growth performance, and hemato-biochemical parameters of Nile tilapia (Oreochromis niloticus) cultured in water recirculating system

This study was carried out to evaluate the effects of humic acid (HA) on the nutrient removal efficiencies of aquatic duckweed plant (Lemna minor) from a water recirculating system used to culture Nile tilapia (Oreochromis niloticus) fish for 30 days. The HA was added to water at three concentrations of 0 (Control), 1.5, and 3 mg/L in triplicate. Water quality parameters, growth performance, and some hemato-biochemical parameters of the fish in variable HA concentrations were compared. The total ammonia nitrogen (TAN) and total phosphorous (TP) removal efficiency of L. minor increased with increasing the HA concentration from 0 mg/L to 3 mg/L (p < 0.05). The concentration of nitrate (NO3 −) in the HA-3 mg/L was higher than that in the other groups on days 20 and 30 of the fish cultivation period (p < 0.05). The growth performance of fish improved in the HA-3 mg/L compared to the other groups. The addition of different concentrations of HA to water had no adverse effect on the hematological properties of the Nile tilapia. The plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) levels in the HA-0 mg/L and HA-1.5 mg/L groups were higher than in the HA-3 mg/L (p < 0.05). No significant differences in the plasma glucose and cholesterol levels were observed between the HA-groups (p > 0.05), while the triglyceride level increased in the HA-3 mg/L compared to the control (p < 0.05). These results indicated that adding HA to water could be an effective method to enhance the bioremediation performance of the aquatic duckweed plants as biofilter and thus improve water quality, subsequently, fish growth performance in RASs.

Exploring the potential of Diplosphaera mucosa VSPA for the treatment of petroleum effluent with simultaneous lipid production.

The discovery of unexplored, robust microalgal strains will assist in treating highly polluted industrial effluent, including petroleum effluent. In the current analysis, a newly isolated microalgal strain, Diplosphaera mucosa VSPA, was used to treat petroleum effluent in a lab-scale raceway bioreactor. Its treatment efficiency was compared with a well-known species, Chlorella pyrenoidosa. The D. mucosa VSPA strain proliferated in petroleum effluent at a high growth rate, with final biomass, and lipid concentrations reaching 6.93 g/L and 2.72 g/L, respectively. Treatment efficiency was calculated based on the final removal efficiency of ammonium nitrogen, phosphate phosphorus, and chemical oxygen demand, which was more than 90%. Control experiments suggested that the maximum removal of pollutants from petroleum effluent was due to microalgae growth. Some growth models, including the Gompertz, Logistic, Stannard, Richard, and Schnute, were used to simulate the experimental data, verifying the results. Good fitting of all models was obtained, with the R2 value reaching more than 0.90. The development of a suitable model can help in decreasing the efforts required for the scale-up of the process.

Hydrogel bioreactor drives Feammox and synergistically removes composite pollutants: Performance optimization, microbial communities and functional genetic differences

Mixed pollutant wastewater has been a difficult problem due to the high toxicity of water bodies and the difficulty of treatment. Rice husk biochar modified with nano-iron tetroxide (RBC-nFe3O4) by polyvinyl alcohol cross-linking internal doping was used to introduce iron-reducing bacteria Klebsiella sp. FC61 to construct a bioreactor. The results of the long-term operation of the bioreactor showed that the removal efficiency of ammonia nitrogen (NH4+-N) and chemical oxygen demand best reached 90.18 and 98.49%, respectively. In addition, in the co-presence of Ni2+, Cd2+, and ciprofloxacin, the bioreactor was still able to remove pollutants efficiently by RBC-nFe3O4 and bio-iron precipitation inside the biocarrier. During the long-term operation, Klebsiella was always the dominant species in the bioreactor. And the sequencing data for functional prediction showed that the biocarrier contained a variety of enzymes and proteins involved in Feammox-related activities to ensure the stable and efficient operation of the bioreactor.

Stress response mechanism of wastewater biological nitrogen removal systems to environmentally realistic concentrations of tire wear particles: Contribution of leachable additives

The study quantified the biological nitrogen removal performance, microbial metabolism, microbial community structure, and antioxidant system in a sequencing batch reactor under long-term exposure to 0.1 and 1 mg/L tire wear particles (TWPs), and determined the contribution of leachable additives to the biotoxicity of TWPs. The results showed that long-term exposure to 0.1 and 1 mg/L TWPs inhibited both the nitrification and denitrification processes, reducing ammonia nitrogen (NH4+-N) and total nitrogen (TN) removal efficiency. The TWP leachate (TWPL) primarily contributed to the denitrification inhibition by TWPs, potentially due to the high concentration of zinc ions in the leachable additive. Furthermore, both TWP and TWPL inhibit nitrogen conversion, with TWP inhibiting the generation and transfer of electrons, while TWPL only negatively affects the electron transfer process. This study presents novel insights into the impact of TWPs on biological nitrogen removal, underscoring its broader implications for the geochemical nitrogen cycle.

Stability of aerobic granular sludge for treating inorganic wastewater with different nitrogen loading rates

ABSTRACT This paper investigated the effect of nitrogen loading rates (NLRs) on the stability of aerobic granular sludge (AGS) for treating simulated ionic rare earth mine wastewater with high ammonia nitrogen and extremely low organic content. Mature AGS from a sequencing batch reactor (SBR) was seeded into five identical SBRs (R1, R2, R3, R4 and R5). The five reactors were operated with different NLRs (0.2, 0.4, 0.8, 1.2 and 1.6 kg/m3·d). After 30 days of operation, R1, R2 and R5 were dominated by broken granules, while most of the granules in R3 and R4 still maintained a complete structure. The properties of granules from R1, R2, R3, R4 and R5 deteriorated to varying degrees, while the granules from R3 and R4 showed better stability than that from R1, R2 and R5. In R1, R2, R3 and R4, the steady-state ammonia nitrogen removal efficiencies were all greater than 90%, and the steady-state removal efficiencies of total inorganic nitrogen (TIN) were approximately 30%. In R5, the removal efficiencies of ammonia nitrogen and TIN were both approximately 70%. The dominant nitrifying and denitrifying bacterial genera of the granules from the five reactors were Nitrosomonas and Thauera, respectively, and their relative abundance was much higher in granules from R3 and R4. The results demonstrated that a relative equilibrium between the growth and metabolism of nitrifying/denitrifying bacteria was achieved when NLR was between 0.8 and 1.2 kg/m3·d, which could provide technical support for the stability maintenance of AGS in the treatment of ionic rare earth mine wastewater.

Growth of Scenedesmus obliquus on anaerobic soybean wastewater using different wasted organics for high biomass production and nutrients recycling

The microalgae culture in mixing sewage with different characteristics may significantly improve biomass production and nutrients recycling efficiency. In this study, three waste organic wastewater including molasses, alcohol and glycerol wastewater were mixed with anaerobic soybean wastewater as mediums for microalgae culture. The optimal mixture of molasses, alcohol and glycerol wastewater was at an initial carbon-nitrogen ratio of 7:1, 5:1 and 10:1, improving biomass production by 60.4%, 31.3% and 68.7%, respectively. The removal efficiencies of organics, ammonia nitrogen and phosphorus at optimal mixture were 54.8–62.4%, 79.5–99.1% and 49.3–61.5%, and the removal rates increased by 340–630%, 27.5–66.3% and 36.3–70.2% compared to the blank culture. In addition, the culture in mixed wastewater increased lipids contrast by 0.7–1.3 times, while achieving higher saturation in fatty acids. The results suggested that microalgae culture using mixed wastewater was a strategy for high biomass production and nutrients recycling efficiency.

Performance evaluation and optimization of simultaneous phosphorus and nitrogen removal from anaerobically digested liquid-dairy-manure using an intermittently-aerated-extended-idle sequencing batch reactor

Wastewater from confined dairy operations requires efficient treatment to reduce its potential to pollute the surrounding environments. In this study, a novel intermittently-aerated-extended-idle sequencing batch reactor (IA-EI SBR) process was developed, evaluated, and optimized for simultaneously removing phosphorus (P) and nitrogen (N) from anaerobically digested liquid-dairy-manure (ADLDM) with lower carbon-to-nutrient-ratios. Four influential operating parameters including cycle-time of 5–9 h, intermittent-aeration strategy of 10–50 min/h, two feed-phases of 6–30 min, and idle-phase of 40–120 min were statistically analyzed using central-composite design coupled with response-surface methodology for optimal removal efficiencies of ortho-phosphorus (%OPremoval), total-phosphorus (%TPremoval), ammonia-nitrogen (%NH3-Nremoval), total-nitrogen (%TNremoval), and chemical oxygen demand (%CODremoval). Results showed that the interactions of cycle time-idle phase, and aeration strategy-feed phases were significant in affecting %TPremoval (p-value ≤ 0.005). The synergistic effect of aeration strategy-idle phase was significant for %TNremoval and %CODremoval (p-value ≤ 0.006), while the cycle time-feed phases interaction had significant effect on %NH3-Nremoval. The maximum simultaneous nitrification-denitrification (SND) efficiency of 85.7% was recorded under influent COD and TN loading of 3,999.2 and 785.7 mg L−1 at 30 min/h aeration time in 7 h. The quadratic regression models based on statistical analysis of the experimental results adequately described the IA-EI SBR performance and showed that the applied levels of operating parameters were highly correlated with all five responses (p-value ≤ 0.030). Operating conditions for optimal IA-EI SBR process efficiency determined by desirability analysis were cycle-time of 8 h, intermittent-aeration strategy of 36 min/h, feed-phases of 24 min, and idle-phase of 100 min. Under these optimal conditions, the corresponding removal efficiencies for OP, TP, NH3-N, TN, and COD of 82.64, 95.82, 92.92, 73.84, and 90.94%, respectively, were achieved in validation experiments.

Ceramic Aggregate Material Formulated with MSWI Fly Ash and Fuel Ash for Use as Filter Media

This study aimed to develop a novel filtering medium ceramic aggregate prepared using municipal solid waste incineration (MSWI) fly ash and the fuel ash from coal power plants, together with small amounts of silicon carbide foaming agent and magnesia flux as additives. For the manufacturing process, the dosage of MSWI fly ash and the sintering temperature were optimized to maximize the performance of the resulting materials. Leaching test results indicated that the heavy metal concentrations in the ceramic aggregate were significantly below the limits proposed by GB5085.3-2007, demonstrating its safety for wastewater treatment. The ammonia nitrogen removal efficiency was assessed, and the removal rate of the developed ceramic aggregate was found to be 16.4% higher than that of zeolite, making it comparable to commercial ceramic aggregate. Scanning electron microscopy and X-ray diffractometer analyses were conducted on the ceramic aggregates. The ammonia-nitrogen-removing mechanism, attributed to adsorption and ion exchange, is discussed based on the microstructural analysis results.

Performance changes in the anammox process under the stress of rare-earth element Ce(III) and the evolution of microbial community and functional genes

The high Ce(III) content in ionic rare-earth tailings wastewater has hindered the application of anammox process in this field. Here, the effect of Ce(III) on the performance of anammox processes was investigated, and the evolution of microbial communities and functional genes was explored using metagenomic sequencing. The results showed that the reactor nitrogen removal rate decreased when the Ce(III) concentration reached 25 mg/L, although ammonia nitrogen removal (92.31%) and nitrogen removal efficiency (81.33%) remained at a high level; however, both showed a significant decreasing trend. The relative abundance of anammox bacteria increased continuously from P1–P5, reaching 48.81%, whereas the relative abundance of Candidatus jettenia reached 33.71% at P5, which surpassed that of Candidatus brocadia as the most abundant anammox bacteria, and further analysis of functional genes and metabolic pathways revealed that Candidatus brocadia was richer in biochemical metabolic genes, whereas Candidatus jettenia had richer efflux genes.

Comparative study on the treatment of swine wastewater by VFCW-MFC and VFCW: Pollutants removal, electricity generation, microorganism community

Swine wastewater, characterized by high organic and nutrient content, poses significant environmental challenges. This study aims to compare the effectiveness of two treatment technologies, namely Vertical Flow Constructed Wetland-Microbial Fuel Cell (VFCW-MFC) and Vertical Flow Constructed Wetland (VFCW), in terms of pollutant removal, electricity generation, and microorganism community dynamics. The results showed that the average removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen, total nitrogen (TN), total phosphorus (TP) and sulfadiazine antibiotics (SDZ) by VFCW-MFC were as high as 94.15%, 95.01%, 42.24%, 97.16% and 82.88%, respectively, which were all higher than that by VFCW. Both VFCW-MFC and VFCW have good tolerance to SDZ. In addition, VFCW-MFC has excellent electrical performance, with output voltage, power density, coulombic efficiency and net energy recovery up to 443.59 mV, 51.2 mW/m3, 52.91% and 2.04 W/(g·s), respectively, during stable operation. Moreover, the microbial community diversity of VFCW-MFC was more abundant, and the species abundance distribution in cathode region was more rich and even than in anode region. At phylum level, the dominant microorganisms in VFCW-MFC included Proteobacteria, Bacteroidota, Firmicutes and Actinobacteriota, which showed good degradation effect on SDZ. Proteobacteria and Firmicutes are also involved in electricity production. Chloroflexi, Proteobacteria and Bacteroidota play a major role in nitrogen reduction.