Analysis of the Effect and Influencing Factors of Rural Domestic Sewage Treatment Based on A^(2)O-MBBR Integrated Process

[Objectives] This study was conducted to solve the prominent problems in the treatment of domestic sewage in southern rural areas of China. [Methods] An integrated process treatment mode of anaerobic/anoxic/aerobic moving bed biofilm reactor (A 2O-MBBR) was proposed to analyze and study its operating effect and influencing factors. [Results] The A^(2)O-MBBR mode had good COD removal efficiency and nitrogen and phosphorus removal performance, and the water quality index of the effluent met the Class A standard of GB181918-2002. This mode is suitable for treating rural domestic sewage, and has high treatment effects in different operating periods. In spring, the average removal rates of COD, NH_(4)^(+)-N, TN, TP and SS reached (83.53 ± 2.15)%, (89.44 ± 4.97)%, (67.36±18.53)%, (88.22±11.21)% and (91.73±2.25)%, respectively;In the autumn period, the average removal rates of COD, NH_(4)^(+)-N, TN, TP and SS were (83.49±2.64)%, (89.26±9.19)%, (66.05±17.00)%, (87.48±9.68)%, and (91.13±2.35)%. [Conclusions] This study provides theoretical reference and technical support for the popularization and application of A^(2)O-MBBR integrated process.

Removal of nitrogen and phosphorus in a combined A^2/O-BAF system with a short aerobic SRT

A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter （A^2/O-BAF） combined system was carded out to treat wastewater with lower C/N and C/P ratios. The A^2/O process was operated in a short aerobic sludge retention time （SRT） for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A^2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitdfying phosphate-accumulating organisms （DPAOs）. The ratio of DPAOs to phosphorus accumulating organisms （PAOs） could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A^2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A^2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A^2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1--4 mg/L nitrate nitrogen in the anoxic zone effluent of A^2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies.

Anoxic Biological Phosphorus Uptake in A^2O Process

A lab-scale anaerobic-anoxic-oxic (A2O) process used to treat a synthetic brewage wastewater was investigated. The objectives of the study were to identify the existence of denitrifying phosphorus removing bacteria (DPB), evaluate the contribution of DPB to biological nutrient removal and enhance the denitrifying phosphorus removal in A2O bioreactors. Sludge analysis confirmed that the average anoxic P uptake accounted for approximately 70% the total amount of P uptake, and the ratio of anoxic P uptake rate to aerobic P uptake rate was 69%. In addition, nitrate concentration in the anoxic phase and different organic substrate introduced into the anaerobic phase had significant effect on the anoxic P uptake. Compared with conventional A2O processes, good removal efficiencies of COD, phosphorus, ammonia and total nitrogen (92.3%, 95.5%, 96% and 79.5%, respectively) could be achieved in the anoxic P uptake system, and aeration energy consumption was saved 25%. By controlling the nitrate recirculation flow in the anoxic zone, anoxic P uptake could be enhanced, which solved the competition for organic substrates among poly-P organisms and denitrifiers successfully under the COD limiting conditions. Therefore, in wastewater treatment plants the control system should be applied according to the practical situation to optimize the operation.

生物膜A^(2)/O工艺处理度假型乡村生活污水的实际运行效果

基于农村生活污水具有体量小、水质水量波动大的特点,区别于市政污水,因此研发了适用于农村生活污水的处理工艺。采用生物膜A^(2)/O工艺处理度假型乡村生活污水,该工程设计最大处理能力150 m^(3)·d^(-1),总水力停留时间40.9 h。为探究该工艺实际运行效果历时10个月,对CODcr、氨氮(NH_(3)-N)和总磷(TP)3个重要指标进行跟踪监测,分析其去除效率及季节气温对去除效果的影响。数据显示,在进水水质水量剧烈波动以及存在冬季低温情况下,CODcr、氨氮和总磷的平均去除率分别为64.32%,51.00%和46.06%,出水平均浓度均达到《城镇污水处理厂污染物排放标准》(GB18918-2002)一级B。冬季进水的3个污染物指标浓度低于夏季,同时季节对COD和氨氮去除率的影响大于对总磷去除率的影响。系统具有较强抗冲击能力,工艺增强了氮的硝化效果。

A^2/O法处理10000m^3/d生活污水工艺设计

近年来,随着经济的不断发展,荆门市水污染问题越来越严重,人们对污水处理的要求也越来越严格。本次设计选用A^2/O工艺处理生活污水,设计规模为10000m^3/d。设计需去除BOD、SS、N、P等,出水要达到《城镇污水处理厂污染物排放标准》(GB18918-2002)中的一级A标准。污水首先经过粗细两道格栅、沉砂池去除大部分的悬浮物及漂浮物,再进入A^2/O池进行生物处理去除BOD、氮、磷等,之后污水进入沉淀池进行泥水分离,随后污水经过消毒后出水。