Effects of temperature on the degradation pathway of domestic sewage in upflow anaerobic sludge blanked reactor

To understand the anaerobic degradation pathway of domestic sewage,three lab-scale upflow anaerobic sludge blanked reactors (UASB) were employed to study the degradation pathway of different particle size and the effect of temperature on this process.Under the operation conditions of the hydraulic retention time of 24 h,the MLVSS of approximate 11200 mg·L-1 and the water temperature at 10,15 and 20℃,the overall degradation pathway of soluble fraction was characterized according to zero-order kinetics.As for the colloidal fraction (between 0.45 and 4.5 μm),the degradation processes followed a first-order kinetic,and should firstly disintegrated into soluble fraction before finally degrading.In contrast,suspended solids (bigger than 4.5 μm) degraded to soluble and colloidal fractions according to first-order kinetics,and the colloidal fraction originating from suspended solids further degraded into soluble fraction which had the same degradation kinetics as the original soluble fraction.There existed the difference of temperature effect on different fraction degradation.Under the temperature at 20,15 and 10 ℃,the first-order rate constant of suspended solids depredating into collide was 4.97,3.01 and 1.01 d-1 respectively.Whereas the degradation of collide to soluble fraction was slightly affected by the temperature change.On the other hand,the zero-order degradation rate constant of soluble fraction was 0.26,0.18 g and 0.12 gCOD·gVSS-1d-1,respectively.     

臭氧对水中摇蚊幼虫氧化灭活效能试验

为确定臭氧对原水中摇蚊幼虫的灭活性能,进行臭氧和液氯灭活蒸馏水中第1龄期摇蚊幼虫的对比试验,在此基础上,考察人工配水和天然原水中臭氧的灭活特征,探讨原水温度和pH对臭氧灭活摇蚊幼虫的影响.结果表明:与液氯相比臭氧对蒸馏水中摇蚊幼虫具有更好的灭活作用,投加量为1.0 mg/L,接触30 min可以达到100%的灭活率;pH在5.5～7.0范围内变化对臭氧的灭活效果不会产生影响;在15～30℃范围内温度升高能够提高臭氧的灭活效果,当原水温度从30℃降低到15℃时摇蚊幼虫的灭活率下降为77.8%.     

Application of multi-stage bio-filtration system for sewage treatment and analysis of the microbial community

The conventional fixed-bed biofilm process has disadvantages of easily blocked,high headloss and short operation cycle.For overcoming these disadvantages,a multi-stage biofilm reactor(MSBFR),in which the lightweight floating filter was dominant,was set up and operated.For detail investigation of the system when treating municipal wastewater,the succession characteristic of microbial community was analyzed by polymerase chain reaction(PCR)-Denaturing Gradient Gel Electrophoresis(DGGE)method.The results showed that the process had high efficiency to removal COD,SS and NH4+-N.The concentration of COD,SS and NH4-N in effluent were maintained lower than 40 mg/L,5 mg/L and 2 mg/L even though the concentration of COD,SS and NH4+-N in influent were 232-663 mg/L,105-245 mg/L and 23.7-62.7 mg/L,respectively,and the empty bed retention time was 3 h.Furthermore,biofilm samples taken from the column 2nd in height were analyzed by PCR-DGGE.The result of PCR-DGGE analysis showed that the microbial community had a little change in height and the dominant groups were Paracoccus sp.,Lactobacillus delbrueckii,Pseudomonas sp.and Bacteroidetes bacterium.     

Power law of particle size distributions in water treatment processes

In this paper,the power law of particle size distributions (PSDs) in conventional water treatment processes is developed. After measuring the particle size distributions of raw-water,settled water and filtered water,a mathematical model between particle diameter and the amount of particles was studied. The value of collision frequency factor β in the PSDs model can be used to represent the collision behavior of particles ,and can be used as foundation exponent to choose suitable coagulation to accelerate particles aggregation. At the same time,the relationship between the value of parameter K and the total particles volume V was deduced. K is defined as particle volume exponent,which can represent the total volume of particles. The degression degree of K shows the removal efficiency of potable water treatment units.     

高校典型建筑供水管网漏损影响因素研究

高校用水大部分集中在宿舍、教学办公楼以及实验楼3类建筑,以这3类建筑作为研究对象,利用灰色关联度分析法基于压力、管龄、管材、给水当量4个因素对建筑管网漏损影响因素进行评价,结果表明:宿舍各因素影响力从大到小为管龄、给水当量、管材、压力;教学办公楼各因素影响力从大到小为压力、管材、给水当量、管龄;实验楼各因素影响力从大到小为管材、管龄、给水当量、压力.     

酒店用水量影响因素与预测模型研究

基于实地走访和问卷调查,收集了全国共计18个酒店的用水量及相关信息数据.采用相关性分析确定了与用水量显著相关的影响因素,并依据数据特点,选择线性回归和稳健回归构建了不同的用水量预测模型.利用各模型预测3栋未包含于样本数据集的酒店的用水量,从中选出预测能力最佳的模型,并评估其是否具有实用价值.结果 表明,稳健回归模型的预测能力最佳,其预测值与真实值的相对误差在25％以内,并且与依据相关标准计算出的用水量相比,稳健回归模型的预测值更接近真实值.     

医院获得性血流感染的流行病学特征研究与分析

目的:考察医院获得性血流感染(NBSI)的流行病学特征,为该类感染的预防提供参考。方法:以我院2009年3月-2013年6月间住院的23500例患者为研究对象,通过临床观察和监测对所有患者NBSI的发生率、分布情况以及病原菌的种类和分布情况等进行统计分析。结果:23500例患者中,共计发生NBSI 173例,总发生率约为0.736%,住院千日感染率约为0.482‰。在NBSI的分布方面,ICU的发生率最高(68.21%)、其次为肾内科(4.04%)和血液科(2.31%)。NBSI的致病菌以革兰氏阳性菌(58.54%)和革兰氏阴性菌为主(31.01%),其次为真菌菌属(11.15%)。结论:NBSI以ICU、肾内科、血液科为高发科室,且致病菌以革兰氏阴性菌和阳性菌为主要代表,应采取针对性的临床预防措施。     

饮用水中摇蚊幼虫的臭氧灭活及其臭氧-活性炭工艺协同去除

进行了臭氧、二氧化氯和液氯灭活低龄期摇蚊幼虫的对比试验,对影响臭氧灭活效果的主要因素进行了考察,在此基础上,探讨了臭氧-活性炭工艺去除水中摇蚊幼虫的可行性.研究表明：与其他两种化学氧化剂相比,臭氧对滤后水中的低龄期摇蚊幼虫具有更显著的灭活作用,臭氧投加量1.0 mg•L^-1,接触25 min可以达到100%的灭活率;增加臭氧反应器水深有利于提高灭活率,在水质中性条件,COD_Mn对灭活效果影响较大.动态试验中,臭氧投加量1.0 mg•L^-1,接触11 min,臭氧对滤后水中的低龄期摇蚊幼虫可以达到100%灭活率;投加量0.8 mg•L^-1,臭氧-活性炭工艺的协同作用可以完全去除水中生物活性减低的摇蚊幼虫.     

机械搅拌混合池三维流场的数值模拟研究

应用Fluent软件对竖轴机械搅拌混合池的三维流场进行了数值模拟。首先通过试验数据进行湍流模型校核,然后计算和分析速度场及湍流强度场。结果表明,RNGκ-ε湍流模型能够对机械搅拌混合池流场进行正确的模拟和预测;混合池内形成了周期性的上下循环流动,桨片区域的速度及湍流强度较大,下层桨片至池底区域具有较大的流动漩涡;挡板的设置消除了流场的"打漩"现象,改善了搅拌效果。研究结果为机械搅拌混合池的设计及运行管理提供了参考依据。     

中国水工业经济政策体系初探

针对市场经济向新兴的水工业提出的挑战，分析现行有关水工业经济政策的状况和存在的问题，提出了社会主义市场经济条件下的水工业政策包括价格，税收，投资信贷，市场刺激，以及经济核算体系等方面的内容。