Sequential nitrification–denitrification process for nitrogenous, sulfurous and phenolic compounds removal in the same bioreactor (original) (raw)
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Chemosphere, 2011
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Nitrate and Nitrite Removal Using a Continuous Heterotrophic Denitrifying Granular Sludge Bioreactor
Chemical Engineering & Technology, 2013
The denitrification potential of a continuous denitrifying granular-sludge bioreactor for concentrated nitrate/nitrite wastes was investigated. Granules were cultivated using nitrite as sole electron acceptor. Complete denitrification could be achieved at nitrite, nitrate, and nitrate-nitrite mixture (50:50) loading rates up to 2.7, 3 and 3 g N L-1 d-1 , respectively. The maximum nitrite and nitrate reduction capacities were limited by the biomass concentration. Removal of nitrate and nitrite was studied with constant biomass concentration at different pH values. A lower pH value resulted in a considerable increase of inhibitory effects of both nitrite and nitrate whereby nitrate exhibited the more significant impact.
Applied Microbiology and Biotechnology, 2009
Efficient nitrification and denitrification of wastewater containing 1,700 mgl−1 of ammonium-nitrogen was achieved using aerobic granular sludge cultivated at medium-to-high organic loading rates. The cultivated granules were tested in a sequencing batch reactor (SBR) fed with 6.4 or 10.2 kg NH 4+-N m−3 day−1, a loading significantly higher than that reported in literature. With alternating 2 h oxic and 2 h anoxic operation (OA) modes, removal rate was 45.5 mg NH 4+-N g−1 volatile suspended solids−1 h−1 at 6.4 kg NH 4+-N m−3 day−1 loading and 41.3 ± 2.0 at 10.2 kg NH 4+-N m−3 day−1 loading. Following the 60 days SBR test, granules were intact. The fluorescence in situ hybridization and confocal laser scanning microscopy results indicate that the SBR-OA granules have a distribution with nitrifers outside and heterotrophs outside that can effectively expose functional strains to surrounding substrates at high concentrations with minimal mass transfer limit. This microbial alignment combined with the smooth granule surface achieved nitrification–denitrification of wastewaters containing high-strength ammonium using aerobic granules. Conversely, the SBR continuous aeration mode yielded a distribution with nitrifers outside and heterotrophs inside with an unsatisfactory denitrification rate and floating granules as gas likely accumulated deep in the granules.
Simultaneous biological removal of nitrogen, carbon and sulfur by denitrification
Water Research, 2004
Refinery wastewaters may contain aromatic compounds and high concentrations of sulfide and ammonium which must be removed before discharging into water bodies. In this work, biological denitrification was used to eliminate carbon, nitrogen and sulfur in an anaerobic continuous stirred tank reactor of 1.3 L and a hydraulic retention time of 2 d. Acetate and nitrate at a C/N ratio of 1.45 were fed at loading rates of 0.29 kg C/m 3 d and 0.2 kg N/m 3 d, respectively. Under steady-state denitrifying conditions, the carbon and nitrogen removal efficiencies were higher than 90%. Also, under these conditions, sulfide (S 2À ) was fed to the reactor at several sulfide loading rates (0.042-0.294 kg S 2À /m 3 d). The high nitrate removal efficiency of the denitrification process was maintained along the whole process, whereas the carbon removal was 65% even at sulfide loading rates of 0.294 kg S 2À /m 3 d. The sulfide removal increased up to B99% via partial oxidation to insoluble elemental sulfur (S 0 ) that accumulated inside the reactor. These results indicated that denitrification is a feasible process for the simultaneous removal of nitrogen, carbon and sulfur from effluents of the petroleum industry. r
CLEAN – Soil, Air, Water, 2017
Biosorption is a common phenomenon, in that organics in wastewater are trapped by sludge flocs. To achieve high nitrogen removal efficiency from the treatment of low chemical oxygen demand (COD) content wastewater, a two‐sludge denitrification/nitrification batch reactor (TDNBR) is successfully established based on the sorption of organic matter by anoxic activated sludge. During 123 days of operation, the TDNBR achieved high ammonia (>99%) and total nitrogen (TN) (80%) removal efficiency. A higher C/N ratio and exchange frequency have no obvious effect on nitrification but effectively enhanced denitrification. The sorption assays indicated that anoxic sludge could take up a large amount of organic matter (23.79–55.62 mg COD g−1 TSS) but has a low sorption capacity of NH4+‐N. Nitrate utilization rate tests reveal that both the soluble and colloidal organics pre‐sorbed on the sludge can be utilized in denitrification with few organics stored as PHA in bacterial cells. Through cycl...
Water Research, 2006
This paper reports about the successful laboratory testing of a new nitrogen removal process called DEAMOX (DEnitrifying AMmonium OXidation) for treatment of typical strong nitrogenous wastewater such as baker's yeast effluent. The concept of this process combines the recently discovered anammox (anaerobic ammonium oxidation) reaction with autotrophic denitrifying conditions using sulphide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. To generate sulphide and ammonia, a Upflow Anaerobic Sludge Bed (UASB) reactor was used as a pre-treatment step. The UASB effluent was split and partially fed to a nitrifying reactor (to generate nitrate) and the remaining part was directly fed to the DEAMOX reactor where this stream was mixed with the nitrified effluent. Stable process performance and volumetric nitrogen loading rates of the DEAMOX reactor well above 1000 mg N/l/d with total nitrogen removal efficiencies of around 90% were obtained after long-term (410 days) optimisation of the process. Important prerequisites for this performance are appropriate influent ratios of the key species fed to the DEAMOX reactor, namely influent N-NO x /N-NH 4 ratios 41.2 (stoichiometry of the anammox reaction) and influent S-H 2 S/N-NO 3 ratios 40.57 mg S/mg N (stoichiometry of the sulphide-driven denitrification of nitrate to nitrite). The paper further describes some characteristics of the DEAMOX sludge as well as the preliminary results of its microbiological characterisation.
Biological denitrification of high strength nitrate waste using preadapted denitrifying sludge
Chemosphere, 2007
Denitrification of synthetic high nitrate waste containing 9032 ppm NO 3-N (40 000 ppm NO 3) in a time period of only 6 h has been achieved in our previous study using activated sludge. The activated sludge culture was acclimatized by a stepwise increase in the nitrate concentration of synthetic waste. In the present work, studies were carried out on the changing microbial population of the sludge and the physiology of nitrate metabolism during the various stages of adaptation process to high strength synthetic nitrate waste. During the course of adaptation, with an increase in the nitrate concentration, a sharp increase in the number of denitrifiers was found with an equally rapid decrease in the nitrifying community. Two key enzymes involved in the first two steps of the denitrification process were also studied during this period. The results of the study suggest that specific enzyme levels increase as the activated sludge adapts itself to higher nitrate concentrations. Biological denitrification of high nitrate waste is a slow process and to increase the rate of denitrification, parameters such as pH, temperature, C:N and biomass concentration of the process were optimized using orthogonal array method. Optimized conditions increased the specific nitrate reduction rate by 54% and specific nitrite reduction rate by 45%.
Biological nitrogen removal over nitritation/denitritation using phenol as carbon source
Brazilian Journal of Chemical Engineering, 2011
A laboratory scale activated sludge sequencing batch reactor was operated in order to obtain total removal of influent ammonia (200; 300 and 500 mg NH 3-N.L-1) with sustained nitrite accumulation at the end of the aerobic stages with phenol (1,000 mg C 6 H 5 OH.L-1) as the carbon source for denitrifying microorganisms during the anoxic stages. Ammonia removal above 95% and ratios of (NO 2-N / (NO 2-N + NO 3-N)) ranging from 89 to 99% were obtained by controlling the dissolved oxygen concentration (1.0 mg O 2 .L-1) and the pH value of 8.3 during the aerobic stages. Phenol proved to be an adequate source of carbon for nitrogen removal via nitrite with continuous feeding throughout part of the anoxic stage. Nitrite concentrations greater than 70.0 mg NO 2-N.L-1 inhibited the biological denitritation process.
Water Research, 2016
Fish processing industries produce wastewater containing high amounts of salt, organic matter and nitrogen. Biological treatment of such wastewaters could be problematic due to inhibitory effects exerted by high salinity levels. In detail, high salt concentrations lead to the accumulation of nitrite due to the inhibition of nitrite-oxidizing bacteria. The feasibility of performing simultaneous nitritation and denitritation in the treatment of fish canning wastewater by aerobic granular sludge was evaluated, and simultaneous nitritationedenitritation was successfully sustained at salinities up to 50 gNaCl L À1 , with a yield of over 90%. The total nitrogen concentration in the effluent was less than 10 mg L À1 at salinities up to 50 gNaCl L À1. Nitritation collapsed above 50 gNaCl L À1 , and then, the only nitrogen removal mechanism was represented by heterotrophic synthesis. In contrast, organic matter removal was not affected by salinity but was instead affected by the organic loading rate (OLR). Both COD and BOD removal efficiencies were over 90%. The COD fractionation analysis indicated that aerobic granules were able to remove more than 95% of the particulate organic matter. Finally, results obtained in this work noted that aerobic granular sludge had an excellent ability to adapt under adverse environmental conditions.