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Zhang M.,Beijing University of Technology | Peng Y.-Z.,Beijing University of Technology | Wang C.,Beijing University of Technology | Wang C.-X.,Beijing University of Technology | And 2 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2015

The start-up and characterization of a three-stage nitrification biological contact oxidation reactor were studied using actual sewage. The experimental results showed that by using the intermediate sedimentation tank effluent as influent for the biofilm incubation in biological contact oxidation reactor, the biofilm matured within 20 day without additional inoculation sludge, and the NH4+-N removal efficiency reached above 98%. The biomass and biofilm thickness of three stages gradually decreased in the flow direction, and the highest biomass and biofilm thickness were 1271.25 mg/L and 119.45 μm respectively. By analyzing the nitrifying characteristics, the results revealed that the three stages had higher specific nitrification uptake rate (SNUR) even at low temperature of 15℃, and the second and third stages were both higher than the first stage at the same temperature (15, 23, 32℃). In view of the above phenomenon, the ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) ratio in each stage were roughly estimated according to the specific oxygen uptake rate (SOUR). The AOB of three stages were (25.64±4.89)%, (34.59±5.02)% and (42.50±1.57)% while the NOB were (23.52±3.35)%, (39.65±4.26)%, (40.69±2.19)% respectively. In addition, the fluorescence in situ hybridization (FISH) results derived on day 125after initial operation showed that the bacterial distribution of three stages do exist differences. The AOB and NOB were more dominant in the second and third stages, compared to the first stage. ©, 2015, Chinese Society for Environmental Sciences. All right reserved.


Zhang M.,Beijing University of Technology | Peng Y.,Beijing University of Technology | Wang C.,Beijing University of Technology | Xue X.,Beijing Enterprises Water Group China Investment Ltd | And 2 more authors.
Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) | Year: 2015

A novel two-sludge process of A2/O-biological contact oxidation (A2/O-BCO) is proposed. Stable and efficient denitrifying phosphorus removal can be realized by high-efficiency utilization of influent carbon sources in the A2/O reactor with the electron acceptors of NOx--N in the BCO reactor. The denitrifying phosphorus removal characteristics of the A2/O reactor under different volume ratios (anaerobic zone/ anoxic zone/ aerobic zone) with real domestic wastewater were investigated. The results show that the system exhibits good stability for organic matter removal, and the variation of the volume ratios has little effect on COD (chemical oxygen demand) removal. When the volume ratio is 2∶4∶1, the effect of nitrogen and phosphorus removal is high, the effluent TN and PO43--P concentrations being 13.41 and 0.28 mg/L respectively. The nitrogen balance analysis results show that the phenomenon of simultaneous nitrification denitrification (SND) exhibits in the BCO reactor, and the occurrence of anaerobic ammonia oxidation (Annamox) contributes to the nitrogen loss. Additionally, the aerobic zone of the A2/O reactor plays an important role in keeping stable effluent PO43--P concentration. In order to prevent secondary phosphorus release, the NOx--N concentration in the middle settler should be controlled to 1.95 to 2.75 mg/L. ©, 2015, Southeast University. All right reserved.


Wang C.,Beijing University of Technology | Wang S.-Y.,Beijing University of Technology | Zhang M.,Beijing University of Technology | Wang C.-X.,Beijing University of Technology | And 3 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014

The characteristics of biological nitrogen (N) and phosphorus (P) removal under different nitrate recycling ratios were investigated in a Anaerobic/Anoxic/Oxic (A2O)-Biological Contact Oxidation (BCO) system when treating low C/N in municipal wastewater. The results indicated that the removal of N and P was achieved simultaneously, and denitrifying phosphorus removal (DPR) process was realized with the total hydraulic retention time (HRT) of A2O at 8h, sludge reflux ratio of 100%, and nitrate recycling ratios set as 100%, 200%, 300% and 400% respectively. The effluent concentration of COD was less than 50mg/L. The removal efficiencies of total nitrogen (TN) were 48.8%, 66.5%, 75.6% and 62.5%, and the removal efficiencies of total phosphorus (TP) were 86.0%, 90.3%, 91.0% and 95.0% under various nitrate recycling ratios. When the nitrate recycling ratio was set at 300%, average concentration of TN and TP in effluent were 14.96mg/L and 0.49mg/L. The amount of denitrifying phosphorus removed was increased slightly as the nitrate recycling ratio improved. When the nitrate recycling ratio was set at 400%, the amount of P removed by DPR accounted for 98% of the total phosphorus removed. ©, 2014, Chinese Society for Environmental Sciences. All right reserved.


Zhang W.,Beijing University of Technology | Xue X.,Beijing University of Technology | Xue X.,Beijing Enterprises Water Group China Investment Ltd | Pang H.,Beijing Enterprises Water Group China Investment Ltd | And 3 more authors.
Huagong Xuebao/CIESC Journal | Year: 2015

Combining anaerobic-anoxic-oxic reactor with an external nitrification biological aerated filter, the AAO-BAF process was used to treat domestic wastewater. Adjusting the influent COD concentration from 211 to 675 mg·L-1, the effect of carbon-nitrogen ratio (C/N) on the performance of the AAO-BAF process was investigated. A low or high influent organic concentration had significant effect on the nutrients removal efficiency due to the deficient phosphorus release or nitrate competition in the anoxic zones of the AAO reactor between DPAOs and ordinary heterotrophic organisms. When C/N was between 4 and 7,the average removal efficiencies of COD, TN and PO43- could reach more than 86%, 78% and 90% respectively. Large quantity of residual volatile fatty acid (VFA)would be transferred into the anoxic zones when C/N was very high (such as 9.5), which would cause rapid consumption of NO-3 by ordinary heterotrophic organisms rather than denitrifying phosphorus accumulating organisms (DPAOs). © All rights reserved.


Zhang W.,Beijing University of Technology | Hou F.,Beijing Beihuaqingchuang Environmental Science and Technology Company | Hou F.,Beijing Enterprises Water Group China Investment Ltd | Liu Q.,Beijing University of Technology | And 5 more authors.
Huagong Xuebao/CIESC Journal | Year: 2014

Integrated anaerobic/anoxic/oxic process with biological aerated filter, AAO-BAF system was used to treat domestic wastewater with low C/N ratio of about 4. By adjusting influent flow rate of the AAO reactor and aeration rate of BAF, the effect of hydraulic retention time (HRT) and aeration rate on the performance of the AAO-BAF system was investigated. The results showed that air/liquid ratio and hydraulic load rate (HLR) of BAF had great influence on NH4 + removal. At air/liquid ratio 3:1, NH4 + removal rate decreased to 72%. Further, when HRT=4 h and HLR of BAF was 3 m3 · m-2 · h-1, NH4 + could not be removed completely even with a high air/liquid ratio of 8:1. This work confirmed that there was an obvious relationship between PO4 - and NH4 + removal efficiencies in the AAO-BAF system. The NH4 + removal should reach 98% for over 90% of the PO4 3- removal. When HRT of the AAO reactor was greater than 6 h, and air/liquid ratio of BAF was greater than 4:1, the average removal efficiencies of COD, NH4 +, TN and PO4 3- could reach 87%, 99%, 80% and 95% respectively. © All Rights Reserved.

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