Effluent Concentrations Of NH4 Research Articles

S0-driven partial denitrification coupled with anammox (S0PDA) enables highly efficient autotrophic nitrogen removal from wastewater

This study proposed a novel strategy that integrates S0 particles (diameter: 2–3 mm) and granular sludge to establish S0-driven partial denitrification coupled with anammox (S0PDA) process for autotrophic nitrogen removal from NH4+- and NO3−-containing wastewaters. This process was evaluated using an up-flow anoxic sludge bed bioreactor, operating continuously for 240 days. The influent concentrations of NH4+ and NO3− were 29.9 ± 2.7 and 50.2 ± 2.7 mg-N/L, respectively. Throughout the operation, the hydraulic retention time was shortened from 4.0 h to 2.0 h, while the effluent concentrations of NH4+ and NO3− were maintained at a desirable level of 1.45–1.51 mg-N/L and 4.46–6.52 mg-N/L, respectively. Despite an autotrophic process, the nitrogen removal efficiency and rate reached up to 88.5 ± 2.0 % and 1.75 ± 0.07 kg-N/(m3·d), respectively, indicating the remarkable robustness of the S0PDA process. Autotrophic anammox and sulfur-oxidizing bacteria (Candidatus Brocadia and Thiobacillus) were the predominant bacterial genera involved in the S0PDA process. Candidatus Brocadia was primarily enriched in the granular sludge, with a relative abundance of 6.70 %. Thiobacillus occupied a unique niche on the S0 particles, with a relative abundance as high as 57.6 %, of which Thiobacillus thioparus with partial denitrification function (reducing NO3− to NO2− without further reduction to N2) accounted for 78.0 %. These findings challenge the stereotype of low efficiency in autotrophic nitrogen removal from wastewater, shedding fresh light on the applications of autotrophic processes.

A novel partial denitrification, anammox-biological phosphorus removal, fermentation and partial nitrification (PDA-PFPN) process for real domestic wastewater and waste activated sludge treatment

A novel process was developed for real domestic wastewater and waste activated sludge (WAS) treatment based on partial denitrification, anammox-biological phosphorus removal, fermentation and partial nitrification (PDA-PFPN). After 246 days of operation, the effluent concentrations of NH4+-N, NO2−-N and NO3−-N were below detection limits (0.1 mg/L), and the effluent concentration of PO43−-P was 0.1 mg/L without the addition of external carbon source in PDA-PFPN system. Moreover, the sludge reduction efficiency reached 48.1% due to fermentation. The nitrite accumulation ratios by ammonia oxidation and nitrate reduction pathway were 60.6% and 87%, respectively. Intracellular metabolites measured by liquid chromatography mass spectrometer (LC-MS/MS) suggested that different intracellular amino acids were stored and consumed at different duration, and intracellular Valine, Glycine and Lysine were not utilized in oxic stage. Results of flow cytometry showed that the proportion of intact cells decreased from 94.7% to 82.9%, and necrotic cells increased from 5.3% to 17.1% with the increase of DNA content in sludge supernatant and cell decay rate, indicating the occurrence of cell death and lysis and leading to WAS reduction. Analysis of transcriptional community composition revealed that partial denitrification bacteria (Thauera), anammox bacteria (Candidatus Brocadia and Candidatus Kuenenia), simultaneous phosphorus removal and fermentation bacteria (Tetrasphaera) and partial nitrification bacteria (Nitrosomonas) coexisted and actually worked in PDA-PFPN system. The novel PDA-PFPN process simultaneously achieved highly efficient nitrogen and phosphorus removal and WAS reduction without the addition of external carbon source, which greatly reduced the operation cost of carbon source dosing and WAS treatment in wastewater treatment.

Partial Nitritation and Anaerobic Ammonia Oxidation Synergistic Denitrification to Remove Nitrogen and Carbon from Domestic Sewage

A sequencing batch reactor-anaerobic sequencing batch reactor(SBR-ASBR) process was used to treat domestic sewage. In the SBR, the effects of the anoxic/aerobic time ratio and temperature on the realization of partial nitritation(PN) were investigated. In the ASBR, the effects of different COD/NO2--N(C/N) ratios on the removal of nitrogen and carbon using anaerobic ammonia oxidation(ANAMMOX) and denitrification were studied. The results illustrated that:① After three single cycles and on the 22nd day, the NO2--N accumulation rate(NiAR) was 98.06%, and the nitrate nitrogen generation rate(SNiPR, calculated as N/VSS) was 0.28g·(g·d)-1, and simultaneous nitrification and denitrification removal the TN and COD were 12.29 and 110.36mg·L-1, respectively(temperature=25℃, anoxic/aerobic time ratio=30 min:30 min). ② At an anoxic/aerobic time ratio of 30 min:30 min, the filamentous sludge bulked, the sludge activity decreased, and sludge settleability was poor at 15℃. Furthermore, the conversion rate of NH4+-N to NO2--N was 86.83%, indicating that the effluent NH4+-N concentration was too low to provide suitable matrix concentrations for ANAMMOX at 30℃. The effluent concentrations of NH4+-N and NO2--N were 31.58 mg·L-1 and 35.04mg·L-1, respectively, matching the ratio of the ANAMMOX substrate at 25℃. ③ The SBR-ASBR combined process showed good denitrification performance; the effluent TN, NH4+-N, and COD concentrations were stable at 13.13, 4.83, and 69.96mg·L-1, respectively, and the removal rates were 83.10%, 93.64%, and 75.11%, respectively. When the influent C/N of the ASBR was 2.5, 2.0, and 1.5, respectively, anaerobic ammonia oxidation and denitrification showed the best performance with respect to nitrogen and carbon removal with a C/N of 2.0. The effluent NH4+-N, NO2--N, NO3--N, and COD were 0.09, 0.25, 1.04, and 32.73 mg·L-1, respectively.

Treatment of wastewater with high carbon-to-nitrogen ratio using a waterfall aeration biofilm reactor combined with sequencing batch reactor: Microbial community structure and metabolism analysis

A low-cost and high-efficiency waterfall aeration biofilm reactor (WABR) combined with a sequencing batch reactor (SBR) was established to treat wastewater with a C/N ratio of 50. Three WABR-SBR systems with different fillers were used. In the stable operation phase, the removal efficiency of chemical oxygen demand was R1 (approximately 99%), R2 (97–99%), and R3 (96–99%); the effluent concentration of NH4+-N was 0.5 mg/L without nitrite or nitrate accumulation. High-throughput 16S rRNA sequencing revealed that the dominant phyla in the microbial community structure were Proteobacteria, Bacteroidetes, and Planctomycetes. Quantitative PCR was used to quantify the nitrification and denitrification gene expressions (Nitrobacter, nirS, and nirK) to evaluate the simultaneous nitrification and denitrification processes. Both anammox and denitrifying bacteria were abundant. Metagenomic annotation of genes that revealed the metabolic pathways of carbohydrates, amino acids, and the two dominant enzymes (GH and GT) provide valuable information for microbial ecology analysis.

Dynamic nutrient removal potential of a novel submerged macrophyte Rotala rotundifolia, and its growth and physiological response to reduced light available

Rotala rotundifolia is a novel submerged macrophyte able to survive across the winter under temperature as low as 4 °C. Dynamic nutrient removal potential of R. rotundifolia was estimated using the Eco-tank system simulating natural eutrophic waters. The growth and physiological response of R. rotundifolia by cutting and division propagation to light (100%, 60%, and 20% natural light) were investigated. The results showed that R. rotundifolia was superior in removing N and P from eutrophic waters. As influent concentrations of NH4+-N and total phosphorus (TP) were 4.81–5.87 and 0.61–0.78 mg L−1, effluent concentrations of NH4+-N, total nitrogen (TN), and TP were separately 0.06–1.10, 0.40–1.59, and 0.05–0.17 mg L−1, with removal efficiencies of 93.6%, 84.6%, and 82.5% at a flow rate of 200 L d−1. The growth and morphology of the plant under two propagation patterns were influenced by light and the responses were quite different. The biomass of the plant by cutting was higher at low light conditions, and the plant allocated more biomass on above ground. However, there was no significant difference in the height. By division, the plant preferred to high light. The biomass and height were significantly higher at 100% natural light. The peroxidase (POD), superoxide dismutase (SOD) and root activities of plant by cutting showed a trend of decrease and followed by an increase with light reduction, while by division, they increased with reduced light available. Variations of chlorophyll and soluble protein of the plant by cutting and division were contrary to the changes of POD activity. These results suggest that R. rotundifolia can be used to effectively remove nitrogen and phosphorus in eutrophic waters, and high light promotes the growth of the plant by division, while suitable shade is needed for the plant by cutting.

Experimental study on the intensive treatment of coal mine domestic sewage by biofilm A/O

In recent years, China attached much significance to the reuse and high standard discharge of domestic sewage. Coal mines in China are mainly distributed in north and northwest t areas with shortage of water. To improve the treatment effects and reuse standard of coal mine domestic sewage, the biofilm A/O reactor with one anoxic zone and two aerobic zones was used to carry out an experiment. The pollutants removal effects and influencing factors were analyzed. The results indicate: Under the conditions of HRT=5.92 h, ρ(DO)A=0.5±0.2 mg/L, ρ(DO)O1=2±0.2 mg/L, ρ(DO)O2=2.5±0.2 mg/L, and R (reflux ration)=100%, the maximal concentration of NH4 +-N, COD, TN and TP in the last effluent were respectively 0.52mg/L, 15.3 mg/L, 13.1 mg/L and 0.78mg/L. Under the conditions of HRT=4.74 h and R=50%, the reactor achieved optimal performance. Moreover, the effluent concentration of NH4 +-N, COD, TN, TP met The reuse of urban recycling water - Water quality standard for industrial uses (GB/T 19923-2005).

Effect of Darcy flux on the release of dissolved organic matter and nitrogen from coal gangue in a coal mine underground reservoir: Column experiments

Underground reservoirs packed with coal gangue have been widely used to store and purify mine water in the coal mine areas of China; however, minimal information is available about the effects of pollutants released from the packed matrix on the quality of stored water. Column experiments were performed at 25 °C and Darcy fluxes of 0.39, 0.73, and 1.56 cm/h to investigate the effect of Darcy flux on the dynamic changes of dissolved organic matter (DOM) and nitrogen released from the packed coal gangue. Results showed that the values of dissolved organic carbon (DOC), UV254, organic nitrogen (ORG-N), nitrate, and total dissolved solids (TDS) in the effluent decreased rapidly within 3.7 pore volumes (PV) at the three Darcy fluxes and then decreased slowly and tended to become stable during the column experiments. However, the effluent concentrations of NH4+–N, which is the major nitrogen released from the packed matrix, and total nitrogen (TN) decreased and increased alternately, which can be relative to the lithology, mineral, and chemical composition of the studied matrix. The quantities of DOC, NH4+–N, ORG-N, and TN released from the studied matrix decreased with Darcy flux, suggesting a positive effect of hydraulic retention time (HRT) on the resolution of pollutants from the studied matrix. Moreover, the microbial environment got weakened with an increase in Darcy flux, as confirmed by the variation trends of the biological/autochthonous index (BIX) and the fluorescence index (FI). Thus, the evident accumulation of NO2− –N and the highest content of NO3−−N were observed due to incomplete nitrate reduction with a low efficiency at 1.56 cm/h. The findings will be helpful in estimating the variation of water quality during the storage of mine water in a coal mine underground reservoir in China.

Construction and Denitrification Performance of A2/O Based on Partial Nitrification Coupled with an ANAMMOX System

To resolve the issue of existing municipal wastewater treatment plants (WWTPs) in China with an insufficient influent carbon source, a bench-scale A2/O process based on partial nitrification coupled with ANAMMOX was constructed by controlling aeration partition ratio, dissolved oxygen (DO) concentration, and sludge retention time (SRT). In this study, the nitrogen removal performance, nitrogen removal pathway, and microbial community structure of the system under different conditions were investigated. The results showed that the system had excellent nitrogen removal efficiency at low-C/N influent (C/N=5). The A2/O reactor had experienced the co-culture stage (Phase 1), screening stage (Phase 2-3), and enrichment stage (Phase 4) successively during the 140-day experiment, and the nitrogen removal pathway changed from nitrification and denitrification to partial nitrification coupled ANAMMOX in the end. The optimal removal efficiencies of 97.69% for NH4+-N and 87.83% for TN were obtained in the enrichment stage (Phase 4), and the effluent concentration of NH4+-N and TN were 1.20 mg·L-1 and 7.03 mg·L-1, respectively. Illumina MiSeq sequencing results showed that the enrichment of AOB including Nitrosomonas and Nitrosospira and the elimination of NOB including Nitrospira, Nitrococcus, and Nitrobacter were the main causes of achieving partial nitrification in the system. The enrichment of AnAOB including Candidatus Kuenenia and Candidatus Jettenia was the key point for the occurrence of ANAMMOX in the system, and thus, played an important role in the achievement of advanced nitrogen removal.

Effect of Step Aeration on a Municipal Sewage Aerobic Granular Sludge System

In order to achieve simultaneous nitrogen and phosphorus removal in low-C/N urban sewage, a sequencing batch reactor (SBR) was operated in anaerobic/aerobic (A/O) mode. Keeping the total aeration volume at 900 L, the aeration strategy was adjusted. The uniform aeration of 2.81 L·(h·L)-1 was changed to "high/low aeration" with high strength 4.22 L·(h·L)-1before low strength 1.88 L·(h·L)-1, and "low/high aeration" with low strength 1.88 L·(h·L)-1 before high strength 4.22 L·(h·L)-1. The experiment investigated the nitrogen and phosphorus removal performance and sludge characteristics of the system under different aeration strategies. The results showed that the nitrogen and phosphorus removal performances of the system under high/low aeration were the best. The effluent concentrations of NH4+-N, NO2--N, NO3--N, and TP were 0, 0.15, 8.12, and 0.04 mg·L-1, respectively. The removal rates of total nitrogen (TN) and total phosphorus (TP) were as high as 78.33% and 99.19%, respectively. Simultaneous nitrification endogenous denitrification (SNED) was clear, with the SNED ratio at 77.08%. Compared with uniform aeration, the system nitrification rate and denitrification rate increased, and the denitrification rate reached 14.33 mg·(g·h)-1, which was the maximum value during the whole operation; the solidity, sedimentation performance, and stability of granular sludge were improved, and the sludge volume index (SVI) was 23.49 mL·g-1. After adjusting the aeration strategy to low/high aeration, the nitrogen and phosphorus removal performance of the system deteriorated, and the removal rates of TN and TP were reduced to 51.26% and 58.32%, respectively. However, the system had the best nitrification performance with ammonia oxidation rate and nitrate production rate at 14.92 mg·(g·h)-1and 7.50 mg·(g·h)-1, respectively, which were their maximum values during the whole operation. Simultaneously, the filamentous bacteria in the granular sludge multiplied, the granular structure became loose, the sedimentation and stability all worsened, and the SVI rose to 40.76 mL·g-1.

Effect of dissolved oxygen on simultaneous removal of ammonia, nitrate and phosphorus via biological aerated filter with sulfur and pyrite as composite fillers

A biological aerated filter (BAF) with sulfur and pyrite as fillers were structured to simultaneously remove NH4+-N, NO3–-N and PO43−-P from secondary effluent. When dissolved oxygen (DO) was 1.2–1.5 mg/L, effluent concentration of NH4+-N, NO3–-N and PO43−-P were below 0.65, 0.47 and 0.18 mg/L, respectively. Meanwhile, Fe2+ production via decomposing pyrite could improve autotrophic denitrification performance. Besides, sulfur and pyrite autotrophic denitrification process (PAD and SAD) aligned with the Zero-order and First-order kinetics models, respectively, indicating that the sulfur had excellent capability of providing electron. Moreover, there was a positive correlation between the nitrogen removal performance and protein-like substances in extracellular polymeric substances. Bacterial community analysis suggested the nitrifiers and autotrophic denitrifiers were simultaneously enriched. Principal component analysis indicated that the DO concentration and type of electron donors impacted bacterial community. Consequently, BAF combined with PAD and SAD processes provides an alternative method to remove nutrients.

Impact of substrate type, depth and retention time on organic matter removal in vertical subsurface flow constructed wetland mesocosms for treating slaughterhouse wastewater

Population growth and the associated demand for meat products is creating an increasing concern on water over slaughterhouse associated pollution of aquatic environments in Sub-Saharan Africa. In Kenya, increasing volumes of strong slaughterhouse wastewater being discharged either untreated or partially treated has necessitated ardent research into sustainable technologies. Vertical sub-surface flow constructed wetlands offer a promising solution. A study investigating the effect of depth, time and substrate variation on organic matter removal from slaughterhouse wastewater was conducted using vertical sub-surface flow constructed wetlands. Experimental out-door mesocosms designed as cylindrical metal tanks of variable depth and substrate were set up at Egerton University, Kenya. Results showed that organic matter removal was highest at 5 day retention time, with removals of about 50%, 55% and 82% for BOD5, COD and TSS respectively. Deeper (0.8 m depth) mesocosms were noted to have significant differences in treatment for TSS and NH4–N compared to shallow (0.65 m) mesocosms. Sand substrate was observed to perform better in BOD5 and TSS reduction compared to quarry dust and gravel. Increase in substrate size was observed to increase removal efficiency of NH4–N at longer retention time. However, effluent concentration of NH4–N fluctuated with removal efficiency averaging at 26.5%. The study demonstrated that vertical sub-surface flow constructed wetlands operated at a longer retention time of 5 days; with intermittent wastewater feeding, facilitated over 50% removal of organic matter in slaughterhouse wastewater.

Characteristics of Denitrifying Phosphorus Removal by A2/O-BAF at Low Temperatures

Low C/N domestic sewage was treated by an A2/O-biological aerated filter (BAF) system at low temperatures (11-14℃). The characteristics of pollutant removal, the ratio of denitrifying phosphorus to nitrogen (ΔPO43-/ΔNO3-N) and effects of aeration flow and effective packing height on nitrification in BAF were studied. The results showed that when the average influent concentrations of COD, NH4+-N, TN and PO43- were 193.1, 58.6, 60.3 and 5.1 mg·L-1 respectively, their effluent concentrations were 46.3, 2.5, 13.4 and 0.3 mg·L-1 respectively, which met the first level A criteria specified in the discharge standard of pollutants for municipal wastewater treatment plant (GB 18918-2002). The linear fitting of ΔPO43-/ΔNO3--N was between 0.47 and 1.75. The normal distribution of mathematical statistics was applied-and the average standard deviation for ΔPO43-/ΔNO3--N were 1.20 and 0.29 respectively. When the aeration flows were 60 L·h-1 and 100 L·h-1, the effluent concentration of NH4+-N was less than 5.0 mg·L-1, corresponding to the effective packing heights in the BAF of 1.8 m and 1.0 m respectively. However, when the aeration flow was increased to 120 L·h-1, the air-water flow led to biofilm detachment, which caused the effluent concentration of NH4+-N to increase beyond 5.0 mg·L-1.

Enhanced Nitrogen and Carbon Removal Performance of Simultaneous ANAMMOX and Denitrification (SAD) with Trehalose Addition Treating Saline Wastewater

Enhanced nitrogen and carbon removal performance of simultaneous ANAMMOX and denitrification (SAD) process with trehalose addition treating saline wastewater was investigated in a sequencing batch reactor (SBR). The optimal nitrogen removal was achieved at 0.25 mmol·L-1 trehalose, during which NH4+-N, NO2--N, NO3--N, and COD could be completely removed. Compared to no addition of trehalose, ammonium removal efficiency (ARE), nitrite removal efficiency (NRE) and total nitrogen removal efficiency (TNRE) increased by 50%, 43% and 46%. Ammonium removal rate (ARR) and nitrite removal rate (NRR) increased by 81.25% and 75%, respectively. With increasing concentration of trehalose to 0.5 mmol·L-1, ARE was only 58.82% and the effluent concentration of NH4+-N was 33.25 mg·L-1. Compared to the Haldane model and the Aiba model, the Luong model was the most suitable to simulate the nitrogen removal performance of SAD with trehalose addition treating saline wastewater. The NRRmax, KS, Sm, and n fitted from Luong model were 0.954 kg·(m3·d)-1, 0 mg·L-1, 184.785 mg·L-1, and 0.718, respectively. Compared to the modified Logistic model and the modified Boltzman model, the modified Gompertz model was the most suitable to describe the degradation of a substrate in a single cycle.

CANON process for nitrogen removal from effluents of municipal sewage treatment plants

The feasibility and performance of nitrogen removal from municipal sewage were investigated through the completely autotrophic nitrogen removal over nitrite (CANON) process in a continuous reactor. CANON process was successfully started up with the transformation of nitrogen into gas by mass-balance analysis. For the synthetic wastewater (up to 480 mg NH4+-N/(L · d)), removal rates of the ammonia nitrogen and total nitrogen (TN) were about 80% and 55%, respectively, at 1.25 h hydraulic retention time (HRT). For the secondary effluent of municipal sewage, the effluent concentrations of NH4+-N and TN were below 5 mg/L and 9 mg/L, respectively. It is in accordance with the water quality standard for scenic environment with the reuse of urban recycling water (GB/T 18921-2002).

Study on Shortcut and Simultaneous Nitrification and Denitrification under Low Temperatures

This paper studies the impact of cooling and warming on shortcut and simultaneous nitrification and denitrification under low temperature. The results show that the effluent concentration of NH4+-N and TN gradually increased, the nitrite accumulation rate decreased when DO was 0.3~0.5 mg•L-1, sludge return ratio was 300%, PH was 7.5~8.5, temperature dropped from 15 °Cto 8°C. From 10°C to 8°C in cooling, the average nitrite accumulation rate was 58.17% in A (HRT=24h) reactor. During the system heating process, treatment effect of the system gradually changed for the better. From 12°C to 15°Cin heating process, the average nitrite accumulation rate was 74.39% in B (HRT=48h) reactor. The system treatment effect in B reactor was better by contrasting A and B reactors, therefore, we can increase HRT to reduce the adverse effects on the system due to the temperature decreases to enhance TN removal effect of system.

Feasibility of a Membrane-Aerated Biofilm Reactor for Wastewater on a Single-Stage Type

The membrane-aerated biofilm reactor(MABR) was specially designed to evaluate its suitability for the treatment of an artificial sewage in laboratory. The paper presented the configuration of the MABR, the performance of MABR on treatment efficiencies(COD, NH4+-N, NO3--N), and the theoretical analysis on treatment efficiencies. After 60 days of operation, the effluent concentration of COD was below 50 mg/L, and the removal efficiency was above 85%; the effluent concentration of NH4+-N was below 20 mg/L, and the removal efficiency fluctuated at the range of 90%; what’s more, the MABR reach the goal of simultaneous nitrification and denitrification(SND). Based on these experiments, the MABR was shown to be a very suitable experimental set-up for wastewater on a single-stage type.