Effect of nitrate concentration on filamentous bulking under low level of dissolved oxygen in an airlift inner circular anoxic-aerobic incorporate reactor

This laboratory research investigated a possible cause of filamentous bulking under low level of dissolved oxygen conditions (dissolved oxygen value in aerobic zone maintained between 0.6-0.8 mgO2 /L) in an airlift inner-circular anoxic-aerobic reactor. During the operating period, it was observed that low nitrate concentrations affected sludge volume index significantly. Unlike the existing hypothesis, the batch tests indicated that filamentous bacteria (mainly Thiothrix sp.) could store nitrate temporarily under carbon restricted conditions. When nitrate concentration was below 4 mg/L, low levels of carbon substrates and dissolved oxygen in the aerobic zone stimulated the nitrate-storing capacity of filaments. When filamentous bacteria riched in nitrate reached the anoxic zone, where they were exposed to high levels of carbon but limited nitrate, they underwent denitrification. However, when nonfilamentous bacteria were exposed to similar conditions, denitrification was restrained due to their intrinsic nitrate limitation. Hence, in order to avoid filamentous bulking, the nitrate concentration in the return sludge (from aerobic zone to the anoxic zone) should be above 4 mg/L, or alternatively, the nitrate load in the anoxic zone should be kept at levels above 2.7 mg NO-3N/g SS.     

缺氧-好氧连续流亚硝化颗粒污泥反应器的启动及稳定运行

在室温下(17~19℃),通过接种成熟的亚硝化颗粒污泥于缺氧-好氧连续流反应器中,研究连续流亚硝化颗粒污泥的启动及稳定运行.结果表明,在启动阶段,颗粒污泥系统的亚硝态氮积累率(NAR)平均超过95%,成功启动了缺氧-好氧连续流亚硝化颗粒污泥系统.将好氧区溶解氧(DO)由(3±0.2) mg·L~(-1)提高到(4.5±0.2) mg·L~(-1),探究DO对于该连续流系统的影响.结果表明,在较高DO下,缺氧-好氧连续流亚硝化颗粒污泥系统仍能保持良好的亚硝化性能,平均NAR大于95%.另外,通过改变进水的水力停留时间(HRT),探究HRT对于该连续流系统的影响.较短的水力停留时间(8.4 h)会加快污泥颗粒在系统中的循环,使破碎的颗粒污泥不能及时重组,致使污泥颗粒沉淀性变差,造成污泥颗粒的流失.HRT增加到12.2h时,颗粒污泥系统得到了恢复,并且可以稳定运行.在运行末(166 d),氨氮去除率和NAR分别为86.7%和96.2%.     

A/O一体式曝气生物滤池处理生活污水

在原水水力负荷为1．1m/h，回流比为2的条件下，考察了缺氧－好氧一体式生物滤池在气水比为4∶1、5∶1和6∶1工况下对生活污水的处理效果。研究结果表明，对生活污水有着良好的处理效果，处理出水可稳定地达到国家二级排放标准。随着气水比的增加，系统对COD、BOD5和氨氮的去除率有所提高，缺氧－好氧暴气一体式生物滤池具有良好的硝化、反硝化效果。硝化作用主要在好氧区完成，反硝化作用在缺氧区45cm处即可完成。     

石化废水生化处理工艺优化及提标改造

针对已建炼化污水处理装置提质达标的需求，采用旋流强化工艺对缺氧-好氧（A/O）池进行改造，生化出水TN由（32.8±8.9）mg/L降至（25.6±5.7） mg/L，TN平均去除率提高了约10百分点，且出水TN达标率达到100%，出水水质稳定达到GB 31570—2015《石油炼制行业污染物排放标准》的TN排放限值要求。旋流强化工艺技术先进，便于实施，适用于石化行业污水处理装置的改造升级，具有广泛的应用前景。