【作者】 孙迎雪；

【导师】 顾平；

【作者基本信息】 天津大学 ， 环境工程， 2007， 博士

【摘要】 膜生物反应器（MBR）应用于医院污水处理工艺不但具有出水有机物和悬浮物浓度低、剩余污泥少等优点,且具有物理消毒作用。课题研究了在工程应用中采用MBR处理医院污水的消毒特征,MBR处理前后污水的氯消毒动力学、氯消毒副产物及其生物毒性。实验结果表明,由于膜和膜面沉积层的截留作用实现了MBR对指示微生物的有效去除,在工程应用中MBR对细菌总数和粪大肠杆菌的平均去除率分别达到2.0～3.9 log和2.8～4.0 log。MBR在连续运行22个月以后,由于膜丝的破损和老化,消毒效果有明显的下降趋势。采用次氯酸钠（NaClO）进行消毒试验,原污水出现明显的“拖尾现象”,其细菌总数和粪大肠菌群的变化符合对滞后和拖尾均有体现的Collins-Selleck模型。MBR出水具有极高的消毒效率,当有效氯浓度为3.0 mg/L,接触时间为2 min时,细菌总数和粪大肠菌群均不被检出,考虑消毒剂瞬时衰减的Chick-Waston模型对NaClO灭活MBR出水中细菌的灭活曲线有最佳拟合效果。为检测消毒前后医院污水中的卤代乙酸（HAAs）,建立了离子色谱与固相萃取结合的分析方法。经过25倍预浓缩后,一溴乙酸的检出限为2.61μg/L,二溴乙酸的检出限为1.30μg/L,其余三种HAAs的检测限为0.48～0.82μg/L,准确度和精密度等测定结果符合一般分析要求。将该方法用于测定三个不同处理工艺的医院污水消毒前后水样中的HAAs,发现A、B和C三个污水处理站氯化消毒前后水样中HAAs的增长率分别为91.28%、63.61%和79.50%。对于医院原污水和MBR出水,要获得相同的CRT值,原污水投氯量显著高于MBR出水,相应耗氯量为MBR出水的5¹0倍;且为了获得更高的CRT,原污水需要的投氯量的增量明显高于MBR出水。当CRT约为0.0075 mg·h/L时,MBR出水中粪大肠菌群即可不被检出,且放置6 h未见再生长现象,此时三卤甲烷、卤代乙酸和可吸附有机卤化物浓度分别为8.01μg/L、19.05μg/L和102.5μg/L,相应的生物毒性为8.96μg/L（以K₂Cr₂O₇计）。要达到同样的消毒效果,原污水产生的生物毒性为MBR出水的4.5倍。更多还原

【Abstract】 Membrane bioreactor （MBR） used in hospital sewage treatment may serve as a pre-disinfection unit, in addition to its solid/liquid separation and biological degradation of pollutants functions, to produce the effluent with high quality. The aim of this study was to evaluate the pre-disinfection characteristics of MBR, chlorination disinfection by-products and the bio-toxicity for the effluent from a MBR treating hospital wastewater.The experimental results show that the removal rates of total bacteria and fecal coliform by this MBR are 2.0³.9 log and 2.8⁴.0 log, respectively, due to the rejection by membrane and the visible cake layer developed on the membrane surface. The disinfection efficiency decreases after the MBR having been operated 22-month continuously, for the membrane fibers’ageing and leakage.In this time-course study, sodium hypochlorite （NaClO） was used as a disinfectant to inactivate the residual indicator microorganisms in the raw wastewater and the effluent from MBR. The total bacteria and fecal coliform in the raw wastewater behaved“trailing effect”obviously, and their kinetic fitting accords with the Collins-Selleck Model, which can express both“lag and trailing”. The results indicated that the total bacteria and fecal coliform in the MBR effluent were completely inactivated when the concentrations of available chlorine were 3.0 mg/L and the contact time was 2 min, meanwhile the concentrations of chlorine residual were less than 1.58 mg/L. With the nonlinear fitting for the experimental data, the Chick-Waston model incorporating a first-order disappearance term for chlorine residual was found to best describe the observed inactivation of total bacteria in the MBR effluent.The ion chromatography combined with solid phase extraction （SPE） method was developed for the analysis of sub-μg/L haloacetic acids （HAAs） concentrations, a class of disinfection by-products formed as a result of chlorination of wastewater. Linearity, repeatability and detection limits of the method were evaluated. The detection limits of monobromoacetic acid and dibromoacetic acid are 2.61μg/L and 1.30μg/L respectively, and the other three rang from 0.48 to 0.82μg/L under 25-folds preconcentration. When the above optimization procedure is applied to three hospital wastewater samples with different treatment processes in Tianjin, and the results indicate that the dichloroacetic acid is the major compound, and the growth ratios of the HAAs after disinfection by sodium hypochlorite are 91.28%, 63.61% and 79.50%, respectively.The chlorine-demands of the raw wastewater are 5¹0 times higher than that of the MBR effluent under the same value of CRT. Also the increasing rate of chlorine-demands in the raw wastwater is quicker along with the increasing of CRT value.To meet the requirement for indicative microorganism （fecal coliform） in the Discharge Standard of Water Pollutants for Medical Organization （GB18466-2005）, the CRT value required for the MBR effluent is about 0.0075 mg·h/L, meanwhile, the concentration of trihalomethanes （THMs）, haloacetic acids （HAAs） and adsorbable organic halogen compounds （AOX） are 8.01μg/L, 19.05μg/L and 102.5μg/L, respectively. And correspondingly the bio-toxity by acute toxicity test with Daphnia magna is 8.96μg/L （K₂Cr₂O₇）, which is much lower than the raw wastewater.更多还原