Average Removal Efficiencies Of NH4 Research Articles

Ammonium nitrogen and phosphorus removal by bacterial-algal symbiotic dynamic sponge bioremediation system in micropolluted water: Operational mechanism and transformation pathways

Construct a bacteria-algae symbiotic dynamic sponge bioremediation system to simultaneously remove multiple pollutants under micro-pollution conditions. The average removal efficiencies of NH4+-N, PO43−-P, total nitrogen (TN), and Ca2+ were 98.35, 78.74, 95.64, and 84.92 %, respectively. Comparative studies with Auxenochlorella sp. sponge and bacterial sponge bioremediation system confirmed that NH4+-N and TN were mainly removed by bacterial heterotrophic nitrification - aerobic denitrification (HN-AD). PO43−-P was removed by algal assimilation and the generation of Ca3(PO4)2 and Ca5(PO4)3OH, and Ca2+ was removed by algal electron transfer formation of precipitates and microbially induced calcium precipitation (MICP) by bacteria. Algae provided an aerobic environment for the bacterial HN-AD process through photosynthesis, while respiration produced CO2 and adsorbed Ca2+ to promote the formation of calcium precipitates. Immobilization of Ca2+ with microalgae via bacterial MICP helped to lift microalgal photoinhibition. The bioremediation system provides theoretical support for research on micropolluted water treatment while increasing phosphorus recovery pathways.

Simultaneous removal of ammonia nitrogen, recovery of phosphate, and immobilization of nickel in a polyester fiber with shell powder and iron carbon spheres bioreactor: Optimization and pathways mechanism

Composite pollutants are prevalent in wastewater, whereas, the simultaneous accomplishment of efficient nitrogen removal and resources recovery remains a challenge. In this study, a bioreactor was constructed to contain Pseudomonas sp. Y1 using polyester fiber wrapped with shell powder and iron carbon spheres, achieving ammonia nitrogen (NH4+-N) removal, phosphate (PO43–-P) recovery, and nickel (Ni2+) immobilization. The optimal performance of bioreactor was average removal efficiencies of NH4+-N, PO43–-P, calcium (Ca2+), and Ni2+ as 82.42, 96.67, 76.13, and 98.29% at a hydraulic retention time (HRT) of 6 h, pH of 7.0, and influent Ca2+ and Ni2+ concentrations of 100.0 and 3.0 mg L−1, respectively. The bioreactor could remove PO43–-P, Ca2+, and Ni2+ by biomineralization, co-precipitation, adsorption, and lattice substitution. Moreover, microbial community analysis suggested that Pseudomonas was the predominant genus and had possessed tolerance to Ni2+ toxicity in wastewater. This study presented an effective method to synchronously remove NH4+-N, recover PO43–-P, and fix heavy metals through microbially induced carbonate precipitation (MICP) and heterotrophic nitrification and aerobic denitrification (HNAD) technology.

Composite biologically active filter (BAF) with zeolite, granular activated carbon, and suspended biological carrier for treating algae-laden raw water

In this study, a composite biologically active filter (BAF) packed with suspended biological carrier (SBC), zeolite, and granular activated carbon (GAC) in order, was set to pretreat the algae-laden synthetic raw water. Over the long-term operation, stable and effective treatment was achieved under the algae concentration as high as 16.64 × 108 cell/L, with average removal efficiencies of NH4+-N, Total Organic Carbon (TOC), and algae cells of 97.7%, 64.0%, and 78.6%, respectively. The pollutant removal of each filter were quantitatively assessed. The results revealed zeolite mainly contributed to the adsorption of NH4+-N (50.1%), GAC enriched the most functional microorganisms and contributed to nitrification (57.1%) and organics biodegradation (TOC: 63.9%, microcystin-LR (MC-LR): 96.8%). The addition of SBC filter enhanced the chemical and microbial removal ability of the BAF system. The structure and distribution of biofilm on each filter were different, GAC biofilm accumulated the most MCs degrading microbes, and the highest microbial community richness and diversity was observed in SBC biofilm. Overall, the composite BAF with zeolite-GAC-SBC is developed for algae-laden raw water pretreatment, enabling the application of BAF in drinking water pretreatment plants.

Acclimation performance of constructed wetland coupled with microbial fuel cell for ammonia treatment of wastewaters at high loading rate

Global challenges on water and energy crisis have pressurized on water treatment industry to put into practice advanced technologies for ensuring a suitable supply of either water or energy services. Compared with other biological treatment technologies, constructed wetland (CW) is widely considered as an efficient eco-technology for wastewater treatment with the advantages of low cost, simple operation and maintenance. Microbial fuel cell (MFC) technology is the recently emerging approach in environmental engineering. The integration of MFCs within vertical up-flow CW systems (VSF-CW) as a sustainable technology, therefore, could provide dual benefits in nitrogen removal of wastewaters and energy recovery simultaneously. This study has preliminarily evaluated the acclimation performance of VSF-CW-MFC systems at the high loading rate (4.2 mg COD/h.L; COD:N = 10:1) of domestic wastewaters containing ammonia. Results demonstrated the potential of VSF-CW-MFC systems in achieving electricity generation and ammonia removal of domestic wastewaters at the high loading rate. The plant presence and influent pH of 7.0 could improve the performance efficiency. Average removal efficiencies of NH4+ and COD in planted microcosms with the influent pH of 7.0 were 43.4% and 79%, respectively.

Growth and nutrient uptake of Myriophyllum spicatum under different nutrient conditions and its potential ecosystem services in an enclosed sea area in the East China Sea

We investigated the growth and nutrient uptake of Myriophyllum spicatum under different nutrient conditions and evaluated its implications for ecosystem services in an enclosed area of Jinshan. The specific growth rate ranged from 1.29%–4.37%/day, and the dissolved inorganic carbon and nitrogen, and phosphorus uptake rates were 1.30–1.62, 0.040–0.453, and 0.003–0.027 mg/(g∙day), respectively, under different nutrient conditions. The O2-production and carbon-sequestration efficiencies in the field were 154.30 and 1.25 mg/(g DW∙h), respectively. The average removal efficiencies of NH4+-N, NO3−-N, NO2−-N, and PO43−-P were 43.05%, 97.03%, 64.26%, and 59.24%, respectively, in M. spicatum-cultivated areas compared with in the open sea. Harvesting of M. spicatum removed 12,936.87, 1289.97 and 114.81 kg of carbon, nitrogen, and phosphorus, respectively, from seawater in Jinshan in Nov, 2018. In conclusion, M. spicatum is a good candidate for integrated macrophyte/animal multi-trophic aquaculture in terms of nutrient extraction and economic diversification in low-salinity environments.

Simultaneous nitrification and denitrification (SND) bioaugmentation with Pseudomonas sp. HJ3 inoculated for enhancing phenol and nitrogen removal in coal gasification wastewater.

A simultaneous nitrification and denitrification (SND) bioaugmention system with Pseudomonas sp. HJ3 inoculated was established to explore the potential of simultaneous phenol and nitrogen removal in coal gasification wastewater (CGW). When the concentration of influent chemical oxygen demand (COD) and total phenols (TPh) was 1,765.94 ± 27.43 mg/L and 289.55 ± 10.32 mg/L, the average removal efficiency of COD and TPh at the stable operating stage reached 64.07% ± 0.76% and 74.91% ± 0.33%, respectively. Meanwhile, the average removal efficiency of NH4 +-N and total nitrogen (TN) reached 67.96% ± 0.17% and 57.95% ± 0.12%, respectively. The maximum SND efficiency reached 83.51%. Furthermore, SND bioaugmentation performed with good nitrification tolerance of phenol shock load and significantly reduced toxic inhibition of organisms. Additionally, the microbial community analysis indicated that Pseudomonas sp. HJ3 was the predominant bacterium in the SND bioaugmentation system. Moreover, the indigenous nitrogen removal bacteria such as Thauera, Acidovorax and Stenotrophomonas were enriched, which further enhanced the nitrogen removal in the SND bioaugmentation system. The results demonstrated the promising application of SND bioaugmentation for enhancing simultaneous phenol and nitrogen removal in CGW treatment.

Long-term effects of environmentally relevant concentration of Ag nanoparticles on the pollutant removal and spatial distribution of silver in constructed wetlands with Cyperus alternifolius and Arundo donax

The widely usage of silver nanoparticles in a range of consumer products inevitably results in its being released to the wastewater. As a result, the potential negative effects associated with AgNPs on wastewater treatment systems need to be assessed to develop the regulatory guidelines. In this paper, the exposure experiment at environmentally relevant concentration (100 μg L−1) were conducted to demonstrate the effects of AgNPs on the pollutant removals in constructed wetlands (CWs) with different plants and the spatial distribution of silver. Before adding AgNPs, the system with Arundo donax (VF2) had the better nitrogen removal than Cyperus alternifolius (VF1). After exposure for about 94 d, the average removal efficiencies of NH4+-N significantly reduced by 32.43% and 23.92%, TN of 15.82% and 17.18% and TP of 22.74% and 20.46% in VF1 and VF2, respectively, while the COD removal had no difference. However, presence of 100 μg L−1 AgNPs for about 450 d showed no inhibition effects on nutrient removals in two experimental CWs. Two wetlands showed high removal efficiencies of about 98% on AgNPs, indicating CWs could play a crucial role to control the AgNPs release to environment. It was found that AgNPs mainly accumulated in the soil layer with the Ag content of 0.45–5.96 μg g−1 dry weight in lower soil and 2.84–11.37 μg g−1 dry weight in upper soil. The roots of Cyperus alternifolius absorbed more AgNPs, with higher bioconcentration factors (1.32–1.44) than that of 0.59 in Arundo donax. The differences of translocation factors on leaves and stems in two test plants showed that AgNPs assimilated by roots in Cyperus alternifolius were more easily transferred to the leaves. The obtained results showed that the macrophyte Cyperus alternifolius could be better choice for immobilization of AgNPs.

Effect of high salinity in wastewater on surface properties of anammox granular sludge

Bacterial surface properties fundamentally affect the stability and aggregation of anammox granular sludge. The variation in the surface properties of the granular sludge at different salinities were investigated to further clarify the effect of salinity on the aggregation of anammox granular sludge in this study. High anammox activity was obtained at a salinity of 30 g/L NaCl, and the average removal efficiency of NH4+N, NO2−-N and TN reached 91.9% ± 1.4%, 97.3% ± 0.4% and 86.3% ± 0.9%, respectively. The sludge particle size in Reactor 1 (with 0 g/L NaCl as control) and Reactor 2 (with 0, 15 and 30 g/L NaCl) increased from 1.62 ± 0.16 mm and 1.59 ± 0.12 mm to 2.71 ± 0.23 mm and 2.44 ± 0.19 mm, respectively, during total operation. PN gradually decreased from 30.58 ± 2.5 mg/g to 18.11 ± 2.1 mg/g, and PS sharply increased from 1.48 ± 0.09 mg/g to 10.52 ± 0.50 mg/g with the increase in salinity. The PS/PN ratio of extracellular polymeric substances (EPS) rapidly increased from 0.05 to 0.58 with an increase of salinity. Fourier transform infra-red spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results showed that salinity inhibited the expression of anammox sludge hydrophobicity by changing surface groups. Binding between multivalent metal ions and EPS was significantly hindered by the high Na+ concentration. The results of this study provided a better understanding of the effect of salinity on the stability and aggregation of anammox granular sludge in saline wastewater treatment.

Performance of the Removal of Nitrogen During Anaerobic Ammonia Oxidation Using Different Operational Strategies

The effects of low substrate ratio, cooling methods, and pH on nitrogen removal performance were studied in a laboratory-scale anaerobic ammonium oxidation reactor (ASBR) while treating simulated domestic waste water. The results illustrated that the average removal efficiencies of NH4+-N and NO2--N increased from 54.4% and 65.3% to 95.8% and 92.5%, respectively, at a temperature of 30℃ and an influent concentration of NO2--N of (30±0.2)mg·L-1. The substrate ratio (NO2--N/NH4+-N) increased from 0.9 to 1.4.However, the removal efficiency of NH4+-N was affected negligibly, and the average removal efficiency of NO2--N decreased to 54.6% when the substrate ratio was increased to 1.6, suggesting that the nitrogen removal performance of anaerobic ammonium oxidation was best when the substrate ratio was close to the theoretical value of 1.32.The average removal efficiencies of NH4+-N and NO2--N decreased from 97.5% and 98.5% to 35.2% and 40.1%, respectively, when the temperature of the reactor dropped from 30℃ to 15℃ at one time. The average removal efficiencies of NH4+-N and NO2--N dropped from 97.7% and 98.6% to 52.7% and 62.4%, respectively, when the ladder cooling method(30℃→25℃→20℃→15℃) was used. The average removal efficiencies of NH4+-N and NO2--N increased initially and then decreased when the pH was increased gradually from 7.7 to 8.5.The highest nitrogen removal efficiency was achieved when the pH was controlled at 8.3 with a substrate ratio of NO2--N/NH4+-N equal to 1.4.

Effect of a strengthened ecological floating bed on the purification of urban landscape water supplied with reclaimed water

A floating bed (FB) system vegetated with calamus, iris, lythrum, and Hydrocotyle vulgaris, and a strengthened FB (SFB) system with zeolite and sponge iron as fillers were simultaneously applied to purify urban landscape water in different zones. The urban landscape water, an artificial lake of approximately 326m2, was supplied with reclaimed water during a six-month experiment. Results indicated that the concentrations of nitrogen (N) and phosphorus (P) in the SFB zone (SFBZ) were significantly lower than those in the control zone (CZ) and the FB zone (FBZ) after six months of operation. The average removal efficiencies (AREs) in the SFBZ, FBZ and CZ were 89.98%, 77.39% and 56.37%, respectively, for ammonia nitrogen (NH4+-N); 92.49%, 79.55% and 47.85%, respectively, for phosphate (PO43−-P). Meanwhile, the average concentration of Chlorophyll a and the algae density in SFBZ during the experiment were 12.54μg/L and 1.31×104cells/mL, which were lower, obviously, than those in the FBZ and CZ. Moreover, the contribution rates analysis of nutrient removal exhibited that the plant absorption in the removal of N and P occupied 27.85% and 26.36%, whereas the filler adsorption occupied 7.93% and 11.93%, respectively, in the SFB. Thus, the water quality of the artificial lake was improved greatly by the SFB which hybridized fillers and FB together. Finally, it was found that the AREs of NH4+-N and PO43−-P in the SFBZ could reach 73.93% and 84.56%, approximately 1.39 and 1.41 times that of the FBZ during the winter. Therefore, the application of an SFB can keep a stable water quality in urban landscape water and avoid the lower removal rate of an FB at low-temperature. In summary, the SFB could effectively improve the water quality of urban landscape water supplied with reclaimed water even in winter.

Nitrogen Removal Performance of Novel HABR Reactor over CANON Process

The startup of novel hybrid anaerobic baffled reactor (HABR) and the feasibility of completely autotrophic nitrogen removal over nitrite (CANON) process were studied. The reactor was operated by gradually decreasing HRT to improve total nitrogen load. After startup, the change of nitrogen concentrations, conductivity, pH and MLSS was measured along the reactor, and then the microbial morphology and spatial structure of bacteria were defined. The test results indicated several points:under the experimental condition of an average NH4+-N of 40 mg·L-1 in influent, the quick start-up process was successfully achieved by continuous operation within 89 days, and stabilized over 187 days. The average NH4+-N and TN concentrations of effluent were below 2 mg·L-1 and 10 mg·L-1 respectively, the average removal efficiencies of NH4+-N and TN reached above 96% and 83% respectively, and a NRR of 0.15 kg·(m3·d)-1 was obtained. During the stable phase, the concentrations of NH4+-N and TN gradually declined along the reactor, while the concentrations of NO2--N and NO3--N remained constant at relatively lower values. The highest nitrogen removal efficiency of ammonia occurred in compartment 1, and the reason was confirmed by SEM and FISH microbiological analysis that enriched functional bacteria of AOB and AnAOB coexisted in compartment 1.

Effect of temperature downshifts on a bench-scale hybrid A/O system: Process performance and microbial community dynamics

Effect of temperature downshifts on process performance and bacterial community dynamics was investigated in a bench-scale hybrid A/O system treating real domestic wastewater. Results showed that the average COD removal in this system reached 90.5%, 89.1% and 90.3% for Run 1 (25 °C), Run 2 (15 °C) and Run 3 (10 °C), respectively, and variations in temperature barely affected the effluent COD concentration. The average removal efficiencies of NH4+-N were 98.4%, 97.8%, 95.7%, and that of TN were 77.1%, 61.8%, 72% at 25 °C, 15 °C and 10 °C, respectively. Although the hybrid system was subjected to low temperature, this process effectively removed NH4+-N and TN even at 10 °C with the average effluent concentrations of 2.4 mg/L and 14.3 mg/L, respectively. Results from high-throughput sequencing analysis revealed that when the operation temperature decreased from 25 °C to 10 °C, the richness and diversity indexes of the system decreased in the sludge samples, while underwent an increase in the biofilm samples. Furthermore, the major heterotrophic bacteria consisted of Lewinella, Lutimonas, Chitinophaga and Fluviicola at 10 °C, which could be central to effective COD removal at low temperature. Additionally, Azospira, one denitrifying-related genus increased from 0.4% to 4.45% in the biofilm samples, with a stable TN removal in response to temperature downshifts. Nitrosomonas and Nitrospira increased significantly in the biofilm samples, implying that the attached biofilm contributed to more nitrification at low temperature.

Characteristics of a novel thermophilic heterotrophic bacterium, Anoxybacillus contaminans HA, for nitrification-aerobic denitrification.

A strain bacterium that is thermophilic, heterotrophic nitrifying, and aerobic denitrifying was isolated and identified as Anoxybacillus contaminans HA for the first time. The identification was based on morphological and physiological characterizations, together with phylogenetic analysis of 16S rDNA sequence. The strain possessed excellent tolerance to high temperatures, with 55°C as its optimum and 60°C as viable. Moreover, NH4 (+)-N and NO3 (-)-N could be efficiently removed under thermophilic and solely aerobic conditions, with little intermediate accumulation. Average removal efficiencies of NH4 (+)-N and NO3 (-)-N at 55°C reached 71.0 and 74.7%, respectively, with removal rates of 5.83 and 32.08mgl(-1)h(-1), respectively. Single-factor experiments suggested that the optimal conditions for both heterotrophic nitrification and aerobic denitrification were glucose as carbon source, NH4 (+)-N range of 50-200mgl(-1), and wide NO3 (-)-N range of 200-1000mgl(-1). These results indicated that strain HA had heterotrophic nitrification and aerobic denitrification abilities, as well as the notable ability to remove ammonium under thermophilic condition. Thus, this strain has potential application in waste-gas treatment.

Characterization of a halophilic heterotrophic nitrification–aerobic denitrification bacterium and its application on treatment of saline wastewater

A novel halophilic bacterium capable of heterotrophic nitrification–aerobic denitrification was isolated from marine sediments and identified as Vibrio diabolicus SF16. It had ability to remove 91.82% of NH4+-N (119.77mg/L) and 99.71% of NO3−-N (136.43mg/L). The nitrogen balance showed that 35.83% of initial NH4+-N (119.77mg/L) was changed to intracellular nitrogen, and 53.98% of the initial NH4+-N was converted to gaseous denitrification products. The existence of napA gene further proved the aerobic denitrification ability of strain SF16. The optimum culture conditions were salinity 1–5%, sodium acetate as carbon source, C/N 10, and pH 7.5–9.5. When an aerated biological filter system inoculated with strain SF16 was employed to treat saline wastewater, the average removal efficiency of NH4+-N and TN reached 97.14% and 73.92%, respectively, indicating great potential of strain SF16 for future full-scale applications.

Nitrogen removal from medium-age landfill leachate via post-denitrification driven by PHAs and glycogen in a single sequencing batch reactor

An anaerobic/aerobic/anoxic (AOA) process in a sequencing batch reactor (SBR) was proposed to treat typical medium-age landfill leachate without extra carbon addition. In a steady-state, the average removal efficiencies of NH4+-N, total nitrogen (TN) and COD were 99.7±0.1%, 98.3±0.3% and 89.8±1.4%, when influent NH4+-N, TN and COD were 1025–1327mg/L, 1346–1854mg/L and 6430–9372mg/L, respectively. In the anaerobic stage, dissolved organic matter was taken up partially and stored as polyhydroxyalkanoates (PHAs) with concomitant consumption of glycogen. In the aerobic stage, PHAs was oxidized and glycogen was replenished in the bacterial cells, when TN of 75.4mg/L was removed via simultaneous nitrification and denitrification (SND). The residual nitrate and nitrite were denitrified completely by utilizing residual PHAs and glycogen as electron donors in the anoxic phase. Denitrifying glycogen accumulating organisms (GAOs) were considered to be playing the major role in the process.

Nitrogen-removal performance and community structure of nitrifying bacteria under different aeration modes in an oxidation ditch

Oxidation-ditch operation modes were simulated using sequencing batch reactors (SBRs) with alternate stirring and aerating. The nitrogen-removal efficiencies and nitrifying characteristics of two aeration modes, point aeration and step aeration, were investigated. Under the same air-supply capacity, oxygen dissolved more efficiently in the system with point aeration, forming a larger aerobic zone. The nitrifying effects were similar in point aeration and step aeration, where the average removal efficiencies of NH4+-N were 98% and 96%, respectively. When the proportion of anoxic and oxic zones was 1, the average removal efficiencies of total nitrogen (TN) were 45% and 66% under point aeration and step aeration, respectively. Step aeration was more beneficial to both anoxic denitrification and simultaneous nitrification and denitrification (SND). The maximum specific ammonia-uptake rates (AUR) of point aeration and step aeration were 4.7 and 4.9 mg NH4+-N/(gMLVSS h), respectively, while the maximum specific nitrite-uptake rates (NUR) of the two systems were 7.4 and 5.3 mg NO2−-N/(gMLVSS h), respectively. The proportions of ammonia-oxidizing bacteria (AOB) to all bacteria were 5.1% under point aeration and 7.0% under step aeration, and the proportions of nitrite-oxidizing bacteria (NOB) reached 6.5% and 9.0% under point and step aeration, respectively. The dominant genera of AOB and NOB were Nitrosococcus and Nitrospira, which accounted for 90% and 91%, respectively, under point aeration, and the diversity of nitrifying bacteria was lower than under step aeration. Point aeration was selective of nitrifying bacteria. The abundance of NOB was greater than that of AOB in both of the operation modes, and complete transformation of NH4+-N to NO3−-N was observed without NO2−-N accumulation.

Enhanced denitrifying phosphorous removal in a novel anaerobic/aerobic/anoxic (AOA) process with the diversion of internal carbon source

A novel anaerobic/aerobic/anoxic (AOA) process is proposed to realize denitrifying phosphorous removal in this study, and the characteristic of the AOA process is transferring part of the anaerobic mixed liquor to the post-anoxic zone for providing the carbon source needed for denitrification. The AOA process was operated for 3months, and the average removal efficiencies of NH4+-N, TN and PO43--P were 93.0±3.1%, 70.3±2.9% and 87.3±11.8%, respectively. A mass balance analysis indicated that 0.49±0.02gVSS−1d−1 of PO43--P and 0.23±0.04gVSS−1d−1 of NO3--N were simultaneously removed in the anoxic zone, and it is speculated that denitrifying phosphorous removal occurred in the AOA process. Furthermore, 0.24±0.06gVSS−1d−1 of TN was removed in the aerobic zone via simultaneous nitrification and denitrification (SND). The results demonstrate that the multi-zone structure of the AOA process favors the enhancement of denitrifying phosphorous removal and SND for municipal wastewater treatment.