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Landfill Leachate Treatment
Published in Eric Senior, Microbiology of Landfill Sites, 2020
Nitrification-denitrification treatment systems exposed to metals capable of precipitating phosphorus should be monitored to ensure sufficient nutrient availability.120 Manoharan et al.120 recommend a minimum soluble phosphorus concentration of 0.5 mg/1. Nitrification of ammonia in leachates is likely to be of increasing importance, as more and more landfill sites are designed to reach a methanogenic state.85 Nitrification should present no problem, provided that an active nitrifying population is present and the environmental conditions for these autotrophic organisms are suitable.118 However, high concentrations of metals could inhibit the process.
Influence of Subsurface Processes
Published in Larry W. Canter, in Groundwater, 2019
Nitrification is defined as the biological oxidation of ammonium-nitrogen to nitrate–nitrogen (Reddy and Patrick, 1981). Nitrification is known to take place in two stages as a result of the activity of chemoautotrophic bacteria of the genera Nitrosomonas (NH4+ → NO2) and Nitrobacter (NO2 → NO3). Both organisms are Gram negative, aerobic, chemoautotrophic rods. These nitrifiers derive energy from the oxidation of ammonium-nitrogen and/or nitrite-nitrogen. These organisms require O2 during ammonium-nitrogen oxidation to nitrite-nitrogen and nitrite-nitrogen oxidation to nitrate-nitrogen. Ammonium oxidation of nitrite can be written as (Reddy and Patrick, 1981): () NH4++112O2→NO2−+2H++H2O
Water quality
Published in David Butler, Christopher Digman, Christos Makropoulos, John W. Davies, Urban Drainage, 2018
David Butler, Christopher Digman, Christos Makropoulos, John W. Davies
In an aerobic environment with low levels of organic material, heterotrophic micro-organisms will no longer be able to thrive. However, another group of organisms known as autotrophs (nitrosomas and nitrobacter) can thrive, provided there is a sufficient source of oxygen. These utilise inorganic nutrients as an energy source (carbon dioxide and oxidised forms of nitrogen, phosphorus, and sulphur). Nitrification is the biological process by which ammonia (an inorganic nutrient) is converted first to nitrite and then to nitrate. This can be summarised as NH4+ + 2O2→NO3− + 2H+ + H2O + newcells + energy
Treatment performance and microbial community under ammonium sulphate wastewater in a sulphate reducing ammonium oxidation process
Published in Environmental Technology, 2021
Dandan Zhang, Li Cui, Hao Zhu, Rayan M A Madani, Jiyan Liang
Elemental sulphur (S0) formation and nitrogen removal were realized by SRAO process. Simultaneous reduction of ammonium and sulphate was achieved in a self-designed reactor; the removal efficiency of NH4+-N was 94.80% and that of SO42–-S was 52.57%. After start-up and acclimatization of this process for 120 days, the average effluent concentrations of NH4+-N and SO42–-S were 6.82 and 76.53 mg·L−1, respectively. Bacteria oxidized ammonium with bicarbonate as the electron acceptor to get energy, it could be a reason which N/S [n(NH4+-N)/n(SO42–-S)] conversion rates had not been unified during the experiment. The mechanism of SRAO reaction ought to be more complex than previously assumed. The sludge acclimated in the reactor had Proteobacteria, Chloroflexi, Acidobacteria and Planctomycetes after the reactor ran for 120 days. Three kinds of nitrification bacteria were found, including Nitrosomonas, Nitrospira, and Denitratisoma. Since the partial nitrifying process and traditional anammox process had also acclimated after the operation of the reactor, the traditional denitrification process was observed as occurring simultaneously with SRAO, which offers a substantial biotechnological potential for the complete removal of ammonium and sulphate.
Simultaneous nitrification and denitrification in the activated sludge systems of continuous flow
Published in Environmental Technology, 2018
Rodrigo F. Bueno, Roque P. Piveli, Fábio Campos, Pedro A. Sobrinho
The activated sludge (AS) process is one of the most commonly used and studied treatment technologies in the wastewater field. Numerous field observations, laboratory studies and models have been used to aid in the understanding and use of this powerful treatment process. This research project examines two specific biological processes, nitrification and denitrification, found to occur in oxidation ditches used for the AS process. Typically, the AS process can provide a high degree of chemical oxygen demand (COD) removal and a high degree of ammonia removal through nitrification, but does not provide a significant amount of denitrification. Nitrification is a process where ammonia is biologically converted to either nitrite or nitrate. The denitrification process biologically converts nitrite and nitrate to nitrogen gas, which is then released into the atmosphere. Nitrification and denitrification require different environments to occur. Nitrification requires the presence of oxygen and a longer solids retention time (SRT). The long SRT has benefit to nitrification, because of the long generation cycles of nitrifying bacteria, rather than grow very quickly.
Effects of metal oxide nanoparticles on nitrification in wastewater treatment systems: A systematic review
Published in Journal of Environmental Science and Health, Part A, 2018
Vikram Kapoor, Duc Phan, A. B. M. Tanvir Pasha
Nitrification is the microbiological process by which ammonia is oxidized to nitrite by AOB and then nitrite is subsequently oxidized to nitrate by NOB. AOB and NOB are collectively known as nitrifying bacteria or nitrifiers. Although activated sludge is a common process for large-scale municipal wastewater treatment, nitrification failure is a too-frequent occurrence, since nitrifiers are inhibited by several environmental and engineering factors, including low temperature, extreme pH, low dissolved oxygen concentration, and a wide variety of chemical inhibitors.[17,18,75,76] Furthermore, nitrifiers grow very slowly; even the fastest growing AOB, Nitrosomonas europaea, has a specific growth rate up to only about 2 d−1.[17] Inhibitory effects from the inclusion of nanoparticles into activated sludge systems can impact the nitrification process, in some cases, reducing nitrification rates, resulting in inefficient overall nitrogen removal.[15,19] Therefore, nitrification inhibition may have important implications for meeting nitrogen discharge limits.