Nitrogen Removal Efficiency Research Articles

Porous ceramsite from construction muck and wheat straw for wastewater treatment

Construction muck (CM) from an excavation project was used to prepare sintered porous ceramsite with wheat straw (WS) as a pore-forming agent. The effect of sintering parameters and the pore-forming agent on the properties and removal efficiency of chemical oxygen demand (COD) and ammonium nitrogen (NH4+–N) (here called AmN) of the porous ceramsite were investigated. It was found that an increase in sintering temperature and time increased the compressive strength but decreased the water absorption. Porous ceramsite of diameter 5–10 mm, sintered at 1155°C for 20 min, with WS of length 5 mm and CM/WS ratio of 12.5%, was found to have the highest connected porosity, accompanied by satisfactory strength, voidage and hydrochloric acid solubility. This porous ceramsite had better removal efficiency for COD than for AmN. The removal efficiency of COD reached 72.3% when the ratio of porous ceramsite to wastewater was 150 g/l, with a COD concentration of 104.97 mg/l. Even after regeneration twice, the porous still had a removal efficiency of 60.2% COD. Physical adsorption was found to play a major role during the adsorption processes of COD and AmN by the pseudo-first-order model.

Response of VFAs Produced by Kitchen Waste Fermentation to Intermittent pH Regulation and Enhanced Denitrification Efficiency

To investigate the effects of intermittent pH regulation on volatile fatty acid (VFA) production during kitchen waste fermentation and its impact on nitrogen removal efficiency in the anaerobic/anoxic/oxic (A2O) process, five experimental groups were set up (pH = 3, 5, 7, 9, and control). The study examined the promotion of soluble chemical oxygen demand (SCOD) and VFA release under different pH conditions and their contribution to total nitrogen (TN) release. Additionally, methanol was used as a control carbon source to explore the enhancement of denitrification efficiency when kitchen waste fermentation broth was used as a carbon source in the A2O process. The results indicated that neutral and alkaline conditions could enhance the release of SCOD and the conversion of VFAs, with a more pronounced effect under alkaline conditions. The maximum concentrations of SCOD and VFAs reached 36,412 and 5947 mg/L, respectively. Furthermore, TN release was most significant under alkaline conditions, being 2.39 times that of the control group. When kitchen waste fermentation broth was used as a carbon source, Proteobacteria and Bacteroidota were significantly enriched. Additionally, the relative abundance of key functional genes (napA, norB, and nosZ) involved in nitrogen cycling and key enzymes ([EC: 1.7.1.15], [EC: 1.7.2.1], and [EC: 1.7.2.5]) were enhanced, which strengthened the denitrification performance.

Removal of Nitrogen and Phosphorus from Municipal Wastewater Through Cultivation of Microalgae Chlorella sp. in Consortium

Demographic growth in developing countries has increased domestic wastewater generation, posing environmental and health risks due to nitrogen and phosphorus accumulation, the main contributors to eutrophication. This study explores microalgae–bacteria consortia for nutrient removal, using Chlorella sp. for its high pollutant assimilation efficiency and biomass production. A lab-scale experiment was designed using response surface methodology to optimize key variables, revealing that lighting and the culture medium significantly influenced biomass production and nutrient removal, with lighting having the strongest statistical impact (p = 0.0002). The optimal conditions (18 μmolm⁻2 s−1 light, municipal wastewater) achieved nitrogen and phosphorus removal efficiencies of 87.16% and 94.43%, respectively. A mathematical model was developed with two independent systems: (1) the first describes biomass generation via photosynthesis, considering CO2 as a limiting substrate, while (2) the second models nitrogen and phosphorus consumption, assuming nitrogen as limiting substrate and introducing an intermediate (I) that couples phosphorus and nitrogen removal. This coupling is regulated by factor k, which represents a percentage of the total consortium consumption rate. Model predictions showed high accuracy for biomass (SE = 0.07186) and phosphorus (SE = 0.63065), but nitrogen exhibited greater deviation (SE = 3.40285). These findings highlight the system’s potential as a sustainable and cost-effective wastewater treatment alternative.

Effects of norfloxacin on the interaction between duckweed and its growth-promoting bacterial assemblages.

Effects of norfloxacin on the interaction between duckweed and its growth-promoting bacterial assemblages.

Biochar-Enhanced Nitrogen Removal in SBBR Under PFOA Stress: The Role of Quorum Sensing

Perfluorooctanoic acid (PFOA), an emerging organic contaminant frequently detected in wastewater, inhibits biological nitrogen removal processes, posing challenges to sustainable wastewater treatment. Mitigating the adverse effects of PFOA while enhancing total nitrogen (TN) removal efficiency remains a critical concern. In this study, three sequencing batch biofilm reactors (SBBRs) were operated under low-oxygen conditions with a C/N ratio of 4.0 to investigate enhanced nitrogen removal under PFOA stress using biochar. Compared to the 78.1% TN removal efficiency in the control reactor (SBBR-0) with an initial TN concentration of 50 mg/L, the addition of PFOA decreased TN removal by 2.3% in SBBR-1, while the combined addition of PFOA and biochar increased it by 3.2% in SBBR-2. Biochar, acting through its electron-donating surface functional groups, mitigated PFOA-induced reactive oxygen species accumulation and increased adenosine triphosphate production. These effects promoted the generation of quorum sensing (QS) signaling molecules, facilitating microbial communication and cooperation. Consequently, the relative abundance of key nitrogen-removing bacteria, such as Thauera (from 7.90% to 9.92%) and Nitrosomonas (from 1.42% to 5.75%), increased, leading to enhanced nitrogen removal efficiency. A metagenomic analysis revealed that biochar significantly reduced the production of antibiotic resistance genes without promoting their dissemination. These findings provide new insights into mitigating the negative effects of PFOA and improving TN removal through QS promotion, offering a potential approach for enhancing the sustainability of wastewater treatment systems.

Effects of High Salinity on Nitrogen Removal Efficiency and Microbial Community Structure in a Three-Stage AO System

This study investigated the nitrogen removal performance of a three-stage AO reactor for refractory TN and the changes in microbial community structure within the activated sludge system under varying sodium chloride concentration conditions. Under an influent sodium chloride concentration of 0 g/L with sufficient carbon source, the removal rates of Total Nitrogen (TN), Chemical Oxygen Demand (CODcr), and Ammonium (NH4+-N) remained stable at 98%, 99.7%, and 99.9%, respectively. When the sodium chloride concentration increased to 20 g/L, the activity of AOB was significantly inhibited, with removal efficiency rates dropping to 83%, 89%, and 70%, respectively, and the NAR increasing to 91.97%. Analytical results demonstrated that both ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) exhibited inhibited metabolic activities, with NOB experiencing earlier functional impairment. Under NaCl concentrations ≤ 10 g/L, conventional nitrogen removal via nitrification–denitrification (ND) remained dominant. When NaCl concentrations exceeded 10 g/L, due to the accumulation of NO2−-N, the phyla Planctomycetota and Proteobacteria maintained dominance in the microbial community, while partial nitrification (PN) and denitrification pathways gradually replaced ND. Extracellular polymeric substance (EPS) secretion emerged as the primary microbial defense mechanism against salinity stress. Experimental findings informed proposed strategies including phased acclimatization for salt-tolerance enhancement, EPS production regulation, and targeted enrichment of functional consortia, which collectively improved the denitrification efficiency by 18.7–22.3% under salinity levels ≤ 20 g/L. This study provides theoretical foundations and technical references for process optimization in hypersaline industrial wastewater treatment systems.

Effect of hydraulic residence time on nitrogen removal from a synthetic mariculture wastewater using a bench-scale recirculating bioreactor embedded with aerobic denitrifying bacteria Marinobacter alkaliphilus strain JY28.

Effect of hydraulic residence time on nitrogen removal from a synthetic mariculture wastewater using a bench-scale recirculating bioreactor embedded with aerobic denitrifying bacteria Marinobacter alkaliphilus strain JY28.

Metagenomic insights into the response of microbial metabolic function and extracellular polymeric substances from microalgae-bacteria consortia to fluoroquinolone antibiotics.

Metagenomic insights into the response of microbial metabolic function and extracellular polymeric substances from microalgae-bacteria consortia to fluoroquinolone antibiotics.

Comparison of the start-up of rotating biofilm contactor reactor with HN-AD bacteria inoculation under high and low influent ammonia conditions.

Comparison of the start-up of rotating biofilm contactor reactor with HN-AD bacteria inoculation under high and low influent ammonia conditions.

Investigations on the Money Plant's Nutrient Removal Efficiency in Nutrient Film Technique Hydroponic System Employing Synthetic Wastewater

ABSTRACTThis study examines money plant (Epipremnum aureum) nitrate nitrogen removal efficiency in a nutrient film technique (NFT) hydroponic system using synthetic wastewater. The aim of the research is to evaluate the plant's capacity for phytoremediation in highly controlled hydroponic environments. The NFT system was maintained at its ideal flow rate of 2 L/h and a hydraulic loading rate of 0.12 m3/d. The parameters of the wastewater were TDS 950–1750 ppm, EC 1–1.6 mS/cm, pH 4.9–5.9, and temperature 25°C–26°C. At the end of 90 days of growth, the plant had an average root length of 19 cm, a shoot height of 129 cm, 97 roots, and 90 leaves. The plants showed varied removal efficacy of BOD5, ranging from 62.8% to 90.1%, and removal efficiency of nitrate nitrogen, ranging from 13% to 83%. These findings suggest that Epipremnum aureum can effectively grow in NFT systems and have potential for use in phytoremediation processes, especially when it comes to eliminating nitrate nitrogen and lowering BOD5 in wastewater.

Intensified performance and mechanism of nitrogen removal in constructed wetland incorporating algal pond for treating low carbon nitrogen ratio wastewater.

Intensified performance and mechanism of nitrogen removal in constructed wetland incorporating algal pond for treating low carbon nitrogen ratio wastewater.

Pyrite and PHBV combined as substrates for groundwater denitrification

ABSTRACT Nitrate pollution in groundwater has steadily increased globally, posing a potential threat to human health. Introduction of exogenous electron donors can significantly enhance nitrogen removal from nitrate-contaminated groundwater. Yet, conventional individual autotrophic or heterotrophic denitrification approaches have the disadvantage of low efficiency or high cost. This study investigated the performance of a laboratory-scale solid-phase denitrification (SPD) permeable reactive barrier (PRB) using a polyhydroxybutyrate-co-valerate (PHBV)/pyrite mixture as an electron donor for groundwater denitrification. Two different mass ratios (1:1 and 1:2) were established for the experimental setup. The results showed that under influent levels between 20 and 37 mg·L-1, the PHBV/pyrite system at a ratio of 1:1 achieved a maximum nitrate removal efficiency of 97.03%, with a nitrate removal rate of 99.13 mg NO 3 − - N NO 3 − - N ·L−1·d−1. Moreover, the PHBV/pyrite system at 1:2 reached 97.65% and 111.04 mg NO 3 − - N ·L−1·d−1 in terms of the optimum nitrate removal efficiency and rate. Dissolved organic carbon was undetectable in the effluent in both systems. The nitrate removal performance of the PHBV/pyrite system at 1:2 was superior to the one at 1:1, implying appropriate addition of pyrite in mixtrophic systems could enhance denitrification in groundwater. Additionally, the dominant genera identified were respectively Cloacibacterium and Acinetobacter in two systems, indicating that varying PHBV/pyrite ratios can modulate the succession of dominant nitrogenremoving microorganisms. Specifically, the system at 1:2 favoured aerobic microbial growth, thereby enhancing the efficiency of biological nitrogen removal. The findings have provided a valuable alternative for mixtrophic denitrification in in-situ remediation of nitrate-polluted groundwater.

Cultivation of anammox bacteria from a tropical lake in Indonesia using a novel filter bioreactor to enhance nitrogen removal efficiency.

This study presents a novel strategy for cultivating anammox bacteria from tropical environments using a filter bioreactor (FtBR). Two bioreactors were inoculated with sediment sludge from an Indonesian lake and operated at different temperatures: tropical ambient (22-28 °C) in Reactor 1 and 35 °C in Reactor 2. After 106 days, Reactor 1 developed a red carmine anammox biofilm, while Reactor 2 remained similar to its initial state. Reactor 1 achieved a higher and more stable nitrogen removal rate (0.27 kg-N/m3·d) compared with Reactor 2 (0.21 kg-N/m3·d), indicating a 28.6% greater efficiency. The operational temperature significantly influenced the diversity and abundance of anammox bacteria. Candidatus Brocadia caroliensis (6.20%) was detected in Reactor 1, whereas Candidatus Anammoxoglobus propionicus (7.64%) and Candidatus Brocadia sinica (1.77%) were found only in Reactor 2. Additionally, Candidatus Brocadia fulgida was more abundant in Reactor 1 (20.04%) than in Reactor 2 (6.84%). These findings demonstrate that temperature plays a crucial role in starting the anammox process in FtBRs with a resident inoculum from tropical environments, significantly affecting bacterial growth and nitrogen removal efficiency.

Integration of steel slag and zeolite enhances simultaneous nitrification and autotrophic denitrification in ultra-low carbon/nitrogen ratio wastewater: Remodeling microbiota and iron metabolism.

Integration of steel slag and zeolite enhances simultaneous nitrification and autotrophic denitrification in ultra-low carbon/nitrogen ratio wastewater: Remodeling microbiota and iron metabolism.

Impact of ibuprofen on nitrogen removal performance and its biotransformation in a coupled sulfur autotrophic denitrification and anammox system.

Impact of ibuprofen on nitrogen removal performance and its biotransformation in a coupled sulfur autotrophic denitrification and anammox system.

Carbon source driven microbial ecological behaviors achieving efficient synchronous elimination of nitrogen and sulfamethoxazole within MABR.

Carbon source driven microbial ecological behaviors achieving efficient synchronous elimination of nitrogen and sulfamethoxazole within MABR.

Current intensity and hydraulic retention time play differential roles in functional gene expression or electron transfer pathways in a pyrite-filled three-dimensional biofilm electrode reactor (P3DBER).

Current intensity and hydraulic retention time play differential roles in functional gene expression or electron transfer pathways in a pyrite-filled three-dimensional biofilm electrode reactor (P3DBER).

Next-generation continuous-flow SBR technology for municipal wastewater treatment: Design and optimisation.

Next-generation continuous-flow SBR technology for municipal wastewater treatment: Design and optimisation.

Revealing real impact of microalgae on seasonal dynamics of bacterial community in a pilot-scale microalgal-bacterial consortium system.

Revealing real impact of microalgae on seasonal dynamics of bacterial community in a pilot-scale microalgal-bacterial consortium system.

Inorganic bioelectric system for nitrate removal with low N2O production at cold temperatures of 4 and 10 °C.

Inorganic bioelectric system for nitrate removal with low N2O production at cold temperatures of 4 and 10 °C.