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The inhibitory effect and biodegradation of benzalkonium chloride (BAC), a mixture of alkyl benzyl dimethyl ammonium chlorides with different alkyl chain lengths, was investigated at a concentration range from 5 to 20 mg/L and different biomass concentrations in an activated sludge system. A solution containing glucose and mineral salts was used as the wastewater in all the assays performed. The inhibition of respiratory enzymes was identified as the mode of action of BAC as a result of oxygen uptake rate analysis performed at BAC concentrations ranging between 5 and 70 mg/L. The glucose degradation in the activated sludge at different BAC and biomass concentrations was well-described with Monod kinetics with competitive inhibition. The half-saturation inhibition constant (KI) which is equivalent to EC50 of BAC for the activated sludge tested ranged between 0.12 and 3.60 mg/L. The high KI values were recorded at low BAC-to-biomass ratios, i.e. less than 10 mg BAC/g VSS, at which BAC was almost totally adsorbed to biomass and not bioavailable. BAC degradation started as soon as glucose was totally consumed. Although BAC was almost totally adsorbed on the biomass, it was degraded completely. Therefore, BAC degradation was modeled using two-phase biodegradation kinetics developed in this study. This model involves rapid partitioning of BAC to biomass and consecutive degradation in both aqueous and solid phases. The aqueous phase BAC degradation rate was twenty times, on average, higher than the solid phase degradation rate. The specific aqueous (kI1) and solid (kI2) phase BAC utilization rate constants were 1.25 and 0.31 mg BAC/g VSS h, respectively. The findings of this study would help to understand the reason of extensive distribution of quaternary ammonium compounds in wastewater treatment plant effluents and in natural water systems although QACs are biodegradable, and develop strategies to avoid their release and accumulation in the environment. 相似文献
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复合膜生物反应器处理生活污水的特性 总被引:1,自引:0,他引:1
通过对投加填料的膜生物反应器处理生活污水的特性进行了系统的研究 ,研究结果表明投加填料的膜生物反应器的上清液及系统出水COD浓度低于不加填料的 ;反应器稳定运行后膜的通透性随运行时间的延长而缓慢下降 ,且较投加填料前明显增大 ;反应器中 ,附着相和悬浮相污泥共存 ,并以附着生长的微生物为主 ,悬浮污泥浓度低可以有效的减缓膜过滤阻力的上升和膜的堵塞 .维持反应器内总污泥浓度较高的条件下 ,使随混合液进入膜分离的悬浮污泥量保持很低 ,减少了其对膜的通透能力的影响 . 相似文献
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本文对风干的红砂岩粗粒土及饱水红砂岩粗粒土路堤填料进行了CBR试验、耐崩解试验、压缩试验和剪切试验.试验结果说明水对红砂岩粗粒土的CBR值影响明显,但是其加州承载比均大于规范要求.红砂岩粗粒土适合作为高等级公路的路基填料,但是在实际工程应用时要注意水对红砂岩粗粒土软化的影响. 相似文献
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城市污水处理过程中壬基酚的迁移转化途径研究 总被引:3,自引:0,他引:3
采用GC—Ms法对北京市某污水处理厂各处理单元的壬基酚(NP)分布状况进行了检测,探讨了城市污水处理过程中壬基酚的迁移转化途径。结果表明,城市污水处理厂进水NP平均浓度为19.26μg/L,出水NP平均浓度为4.57μg/L。由于泥区回流液中NP浓度较高,导致NP浓度随水处理流程有先升高后降低的趋势,沉砂池出水NP浓度最高,为进水浓度的1.5倍。在污水处理流程中,除原水外,泥区回流液是NP的一个重要来源;NP的迁出与去除途径包括:初沉池生污泥和二沉池活性污泥的吸附作用,曝气池内的生物降解作用以及随处理出水的排放。 相似文献
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Biodegradation potential of bulking agents used in sludge bio-drying and their contribution to bio-generated heat 总被引:1,自引:0,他引:1
Straw and sawdust are commonly used bulking agents in sludge composting or bio-drying. It is important to determine if they contribute to the biodegradable volatile solids pool. A sludge bio-drying process was performed in this study using straw, sawdust and their combination as the bulking agents. The results revealed that straw has substantial biodegradation potential in the aerobic process and sawdust has poor capacity to be degraded. The temperature profile and bio-drying efficiency were highest in the trial that straw was added, as indicated by a moisture removal ratio and VS loss ratio of 62.3 and 31.0%, respectively. In separate aerobic incubation tests, straw obtained the highest oxygen uptake rate (OUR) of 2.14 and 4.75 mg O2 g−1VS h−1 at 35 °C and 50 °C, respectively, while the highest OUR values of sludge were 12.1 and 5.68 mg O2 g−1VS h−1 at 35 °C and 50 °C and those of sawdust were 0.286 and 0.332 mg O2 g−1VS h−1, respectively. The distribution of biochemical fractions revealed that soluble fractions in hot water and hot neutral detergent were the main substrates directly attacked by microorganisms, which accounted for the initial OUR peak. The cellulose-like fraction in straw was transformed to soluble fractions, resulting in an increased duration of aerobic respiration. Based on the potential VS degradation rate, no bio-generated heat was contributed by sawdust, while that contribution by straw was about 41.7% and the ratio of sludge/straw was 5:1 (w/w, wet basis). 相似文献
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