Characteristics of molecular weight distribution of dissolved organic matter in bromide-containing water and disinfection by-product formation properties during treatment processes

The characteristics of dissolved organic matter (DOM) and bromide ion concentration have a significant influence on the formation of disinfection by-products (DBPs). In order to identify the main DBP precursors, DOM was divided into five fractions based on molecular weight (MW), trihalomethane formation potential and haloacetic acid formation potential were determined for fractions, and the change in contents of different fractions and total DBPs during treatment processes (pre-chlorination, coagulation, sand filtration, disinfection) were studied. Moreover, the relationship between bromide concentration and DBP generation characteristics in processes was also analyzed. The results showed that the main DBP precursors were the fraction with MW < 1 kDa and fraction with MW 3−10 kDa, and the DBP''s generation ability of lower molecular weight DOM (< 10 kDa) was higher than that of higher molecular weight DOM. During different processes, pre-chlorination and disinfection had limited effect on removing organics but could alter the MW distribution, and coagulation and filtration could effectively remove organics with higher MW. For DBPs, trihalomethanes (THMs) were mainly generated in pre-chlorination and disinfection, while haloacetic acids (HAAs) were mostly generated during pre-chlorination; coagulation and sand filtration had little effect on THMs but resulted in a slight removal of HAAs. In addition, the results of ANOVA tests suggested that molecular sizes and treatment processes have significant influence on DBP formation. With increasing bromide concentration, the brominated DBPs significantly increased, but the bromine incorporation factor in the processes was basically consistent at each concentration.     

煤质粉末活性炭自燃和热稳定性分析

针对煤质粉末活性炭最显著的热危险特性——自燃危险性进行试验。采用粉尘层最低着火温度测定系统对煤质粉末活性炭进行自燃试验,测定煤质粉末活性炭的最低着火温度;采用SDT Q600热重分析仪测定煤质粉末活性炭在氮气和空气气氛中以20℃/min的速率升温至700℃时的热解和燃烧特性,通过TG/DTG曲线计算其着火温度,并进行热稳定性评价。粉尘层自燃试验结果表明,煤质粉末活性炭最低着火温度为400℃,具有自燃危险性,易形成阴燃;氮气气氛中热解试验表明,热解过程经历了室温~120.0℃和280.0~700.0℃两次轻缓失重阶段,646.44℃时挥发分热失重速率最大,对应热失重速率峰值为0.082 6%/℃,自燃危险性较低;空气气氛中燃烧试验表明,燃烧过程经历了室温~95.5℃和300.0~600.0℃两次剧烈失重阶段,分别为吸附水分受热蒸发和氧化生成的有机官能团分解脱附导致,565.35℃时挥发分热失重速率最大,对应热失重速率峰值为13.20%/min,粉末较强的氧气吸附效应和较低的导热系数导致其自燃倾向较高,火灾危险性较大。     

区域污染源排污总量分配方案初探

文章以实现区域可持续发展为目标,对区域污染物排污总量的分配进行了初步探索,通过分析对其有影响的各种因素,最终为特定区域发展规划的制定,可持续发展的实现,提供了一种较好的污染物排污总量分配方案。     

池塘悬浮物COD值与灼烧减重燃烧热值的定量关系

为了快速监测水体悬浮有机物的数量,文章采用密封法测定COD,研究了池塘水体悬浮物及固体干物质样品的COD值与燃烧热值及灼烧减重之间的定量关系。结果表明:池塘水体悬浮物及固体干物质样品的COD值与燃烧热值及灼烧减重之间存在显著的相关关系。而且池塘水体悬浮物的COD值与燃烧热值之间的线性回归关系极显著,回归方程为,燃烧热值(J/L)=12.34COD(mg/L)+329.9。给定燃烧热值与有机碳的量以及与有机物量之间的换算系数,就可以推算出池塘悬浮有机物的数量。研究提出了一种池塘水体悬浮有机物的间接定量方法。     

未确知测度模型在污水处理厂评价中的应用

污水处理厂的运行管理效果涉及到污水处理厂的处理水量、水质和能耗等诸多项指标,是多指标综合评价问题。文中将未确知测度综合评价模型应用于污水处理厂运行效果评价中。鉴于在多指标识别问题中,专家难以凭借个人经验确定客观型指标权重,文中采用了信息论中熵的概念来确定评价指标权重,使评价结果更加客观合理。未确知测度模型对评价空间实现了有序分割,提高了分辨率,评价效果可靠,是一种实用模型。     

熵权多目标决策模型在水环境质量综合评价中的应用

介绍了熵和熵权的概念与性质,在此基础上结合多目标决策模型建立熵权多目标决策评价方法,并对水环境质量进行综合评价,评价结果与物元分析模型、属性识别理论方法、模糊隶属函数法进行对比,结果表明,利用熵权多目标决策评价法进行水环境质量综合评价是可行的。     

滨海石化项目环境综合风险评估方法研究

研究针对国内目前的研究现状,运用环境风险评价指数法建立滨海石化项目环境风险评估体系,采用层次分析法和熵权法结合的组合赋权法,结合专家咨询法进行指标的修改与完善,运用线性加权组合法对评估体系中指标权重的赋值,并计算滨海石化项目的环境风险等级,确定项目的风险强弱.实例分析表明环境风险管理在环境风险的产生和预防占有十分重要的地位,通过加强和完善环境风险的管理体系,结合环境因素的敏感程度及风险源的产生和影响,能降低环境风险及事故的影响程度.     

Improving biodegradation potential of domestic wastewater by manipulating the size distribution of organic matter

Carbon source is a critical constraint on nutrient removal in domestic wastewater treatment. However, the functions of particulate organic matter (POM) and some organics with high molecular weight (HMW) are overlooked in the conventional process, as they cannot be directly assimilated into cells during microbial metabolism. This further aggravates the problem of carbon source shortage and thus affects the effluent quality. Therefore, to better characterize organic matter (OM) based MW distribution, microfiltration/ultrafiltration/nanofiltration (MF/UF/NF) membranes were used in parallel to fractionate OM, which obtained seven fractions. Hydrolysis acidification (HA) was adopted to manipulate the MW distribution of dissolved organic matter (DOM) and further explore the correlation between molecular size and biodegradability. Results showed that HA pretreatment of wastewater not only promoted transformation from POM to DOM, but also boosted biodegradability. After 8 hr of HA, the concentration of dissolved organic carbon (DOC) increased by 65%, from the initial value of 20.25 to 33.48 mg/L, and the biodegradability index (BOD5 (biochemical oxygen demand)/SCOD (soluble chemical oxygen demand)) increased from 0.52 to 0.74. Using MW distribution analysis and composition optimization, a new understanding on the characteristics of organics in wastewater was obtained, which is of importance to solving low C/N wastewater treatment in engineering practice.     

环保PPP的八维变量分析及在重金属污染治理中的应用

对PPP应用的主要领域做了分析,并对市政环保领域利用"八维变量分析法"进行了研究,分别从资产条件、项目条件、经营条件3个方向对投资强度、资产沉淀性、资产变现、供应预期、边界清晰度、付费模式、经营增值空间和公益偏见八个变量展开研究,对重金属治理的PPP应用进行了分析,提出重金属治理PPP领域主要存在于环境监测与检测、末端治理和环境修复市场。     

人口统计学变量对环境保护公众参与意识的影响实证研究

采用问卷调查和数理统计等研究方法,研究了人口统计学变量在环境保护公众参与意识上的差异,以及与环境保护公众参与各个变量之间的相关性。结果表明:居民的年龄在公众环保行为和环保政策满意度上呈现显著性差异,居民的职业在环境保护认知、公众环保行为环保政策满意度上呈现显著性差异,居民的受教育程度在环境保护认知、个人环保习惯、公众环保行为、环保政策满意度上呈现显著性差异。婚姻状况与公众环保行为、环保政策满意度之间存在显著性负相关,年龄与环境保护认知之间存在显著性正相关,与环境政策满意度、环境表现满意度之间出现显著性的负相关性,职业与环境保护认知、个人环保习惯、公众环保行为之间存在显著性正相关性,与环保政策满意度、环保表现满意度之间存在显著性负相关。