Oxic Bioreactor Research Articles

Double anammox process in the AOAO process of treating real low C/N sewage: Validation, enhancement, and quantification of the contribution of anammox in the oxic zone

Enhancement of anaerobic ammonium oxidation (anammox) process and enrichment of anammox bacteria in the oxic zone of mainstream sewage treatments are complex. Also, quantification of the anammox contribution for nitrogen removal in the oxic zone is hindered owing to the simultaneous occurrence of anammox and nitrification. An alternating anaerobic/oxic/anoxic/oxic bioreactor whose oxic zone boosted partial nitrification coupling anammox (PN/A) and anoxic zone boosted partial denitrification coupling anammox (PD/A), respectively, was operated to treat real sewage for >380 days. Desirable nitrogen removal (effluent total inorganic nitrogen (TIN) of 4.7 ± 1.9 mg N/L) was obtained from low carbon/nitrogen (3.6 ± 0.5) sewage with ammonium concentration of 52.5 ± 2.2 mg N/L in the influent. Under the condition of dissolved oxygen (DO) of 1.5–3 mg/L, anammox bacteria was still enriched within the aerobic biofilms, with the relative abundance increasing to 8.2 % (day 345) from 0 % (no biomass on day 1), which was higher than the value in the flocculent sludge (0.03 %) (P < 0.001). PN driven by flocculent sludge with high activity of ammonium oxidized bacteria (AOB) ensured sufficient nitrite supply for the anammox process with the existence of continuous DO. During the steady operation period, the maximum anammox contribution in the oxic zone was quantified to be 10.6 % by withdrawing aerobic biofilms from the system.

Effect of aniline and antimony on anaerobic-anoxic-oxic system with novel amidoxime-modified polyacrylonitrile adsorbent for wastewater treatment

There has been increasing concern over the mixed discharge of municipal-textile composite wastewater, which remains challenging for typical wastewater treatment plant (WWTP) using anaerobic-anoxic–oxic process (AAO). Highly-toxic aniline and antimony, typical co-contaminants in textile wastewater, usually lead to increased chemical oxygen demand (COD) in influent and deteriorated effluent quality. Amidoxime-modified polyacrylonitrile (amPAN) adsorbent was prepared and added to adsorb antimony and facilitate substrate removal. With amPAN dosage at 6.0 g L−1 in oxic bioreactor, 64.2 ± 5.6% of antimony was removed from influent. Extracellular polymeric substance release was simultaneously changed with residual antimony concentration. Meanwhile, amPAN promoted the proliferation of Proteobacteria, Bacteroidetes and Epsilonbacteraeota serving as microorganism carrier. As a result, removal efficiencies of COD (94.4 ± 0.6%), ammonium (NH4+-N, 92.6 ± 3.3%), total nitrogen (TN, 76.4 ± 6.3%) and total phosphorus (TP, 93.4 ± 2.1%) were enhanced to meet Class 1A discharge standard in China. These results indicate that AAO with amPAN is promising for municipal-textile composite wastewater treatment.

Life cycle assessment of A2O bioreactor for meat processing wastewater treatment: An endeavor toward the achievement of environmental sustainable development

Due to the limited available water resources and their increasing pollution, the estimation of life cycle assessment thanks to the application of wastewater treatment plants has been brought to close attention by researchers in the last years. Therefore, in the present study to evaluate the life cycle assessment of the applied up-flow anaerobic, anoxic, oxic bioreactor, the direct-practical data were collected and utilized with the aim to promote knowledge in respect of the possible damages of meat processing wastewater treatment plants for the environment. Accordingly, the CML-IA baseline 2000 and ReCiPe Midpoint (H) methods were chosen because of more reliable and comprehensive information which those presented. Generally, the results demonstrated that the bioreactor was an environmentally friendly system to treat meat processing wastewater. The evaluation of eutrophication potential manifested that phosphate contribution was more than 60% for ReCiPe Midpoint (H) and 99.8% for CML-IA baseline 2000, respectively. In addition, the estimation of cumulative energy demand revealed 70 MJ energy consumption belongs to the electricity generation which can be saved by controlling temperature, aeration, and the system leak. Conclusively, the obtained findings illustrate an integrated wastewater management policy to assist managers for investment decisions.

Bacterial Detoxification of Copper and Its Impacts on Germination Indices of Barley and Mung Bean

N ACCOUNT of incessant human activities, copper is ……...accumulated in the environment at elevated concentrations that induce harmful influences on all kinds of living organisms. An oxic bioreactor was employed to transform copper ions into copper particles using volatile metabolites of

Influence of important operational parameters on performance of a membrane biological reactor

In order to elucidate optimum operational parameters, five series of experiments with bench scale “A/O and MBR (membrane biological reactor)” devices were carried out. The HRTs of each anoxic and oxic bioreactor were maintained for 2˜6 h and for 3˜6 h, respectively. The internal recycle ratios were also changed from 100% to 300% of the influent feeding rate by peristaltic pump. There were no recognizable differences in the values of BOD removal efficiency, being around 99%, in the series of experiments. The same was true for T–N removal efficiency, which ranged about 60%. The similarity of the serial experiments for each parameter indicates that the extraordinarily high concentration of microorganisms in the bioreactor, i.e. 10,000–15,000 mg/l, strongly controls the entire process regardless of any moderate changes of the operational parameters.