Evaluating factors that influence microbial phenanthrene biodegradation rates by regression with categorical variables

To advance the accuracy of bioremediation measurements, it is useful before specific experiments to attribute or estimate the influence of both experimental as well as field conditions on the expected magnitudes of microbial degradation rate coefficients. This paper analyzes the numerical contribution, or influence, of categories of conditions, such as bacterial adaptive state, electron acceptor type, mixing, generalized sorption conditions, and biodegradation temperature, on published phenanthrene biodegradation rates as an example of our regression approach. A fundamental microbial degradation rate equation is transformed to an additive model, then using multiple linear regression on published data, coefficients (of categorical variables) and a linear model are presented that estimate first-order biodegradation rate coefficients to within a factor of 3. Numerical estimates of how much bacterial adaptive state and presence of a sorption phase, the two most statistically significant factors, alter the phenanthrene biodegradation rate are presented. The influence of some measurement or field conditions, for example, the influence of oxygen reduction versus optimal nitrate reduction, cannot be distinguished statistically given the available data and range. The regression model is tested using conditions from newly published papers to estimate a priori the expected rate, which compares very favorably to measurements reported in the papers. Due to limited published data and range for extreme cases, the current coefficients do not apply to degradation of very aged phenanthrene nor very low concentrations of electron acceptors. As estimating tools, however, the coefficients themselves and the regression approach have very beneficial roles in design of experiments for both laboratory and field settings. Our method can be applied to other PAHs as sufficient data become available.     

改进改良式序列间歇反应器脱氮除磷试验研究

针对6池MSBR工艺除磷效果不佳和污泥上浮问题,试验通过对流程的巧妙安排以及浓缩池的设置,较好地解决了脱氮和除磷之间的矛盾.根据污泥龄(SRT)选择实验,确定温度为25 ℃、pH为7～8、 SRT为15 d、厌氧池HRT为60 min、缺/厌氧池HRT为30 min的条件下进行脱氮除磷试验.试验结果表明,改进的MSBR工艺的脱氮和除磷效果都比较好,对COD、氮、TP的去除率分别为94.2%、81.4%、88.5%.     

Destruction of phenol aqueous solution by photocatalysis or direct photolysis

The photodegradation of phenol has been investigated under a high-pressure mercury lamp with a kind of jacket (glass or quartz) depending on used UV light range and a variety of experimental conditions: UV (lambda > 200 nm) with oxygen or with TiO2 and oxygen or with N2; UV (lambda > 330 nm) with oxygen or with TiO2 and oxygen or with N2. Photocatalysis and direct photolysis of phenol have different reaction pathways. Direct photolysis of phenol yielded a brown-yellow complex organic polymer in both aerobic and anaerobic environments. The polymer cannot be mineralized in an anaerobic environment. The effects of catalyst amount and oxygen concentration in the reaction atmosphere on the destruction of phenol were studied. The results prove that an appropriate catalyst amount can avoid direct photolysis and increase the mineralization rate of phenol.     

洗车废水处理技术现状与展望

洗车废水中含有泥砂、油乳化液、有机物及洗涤剂类污染物质。在分析中 ,对洗车废水的水质进行了分类 ,并针对不同的水质 ,对国内的大型洗车场的处理工艺和小型洗车行的洗车废水回用工艺进行了介绍和分析 ,对国外采用膜工艺处理洗车废水的相关研究也进行了简要的介绍 ,同时提出了洗车废水的污泥处理问题。从社会、经济效益来看 ,洗车废水回用是必然趋势。现行的洗车废水回用处理工艺回用率低、处理效果不理想 ,采用高效、简单、实用、经济的原则进行设计 ,满足社会对洗车水回用的需求是未来洗车废水处理技术发展的要求     

上海郊区稻田氮素流失研究

通过测坑和大田小区试验，研究了上海郊区稻田氮素排水流失和渗漏流失的特征、相关因素和流失负荷。结果表明，稻田综合排水TN为6.55mg／L，流失负荷为16．68kg／hm^2，以铵态氮为主，稻田氮素的排水流失负荷为16．68kg／hm^2。稻田渗漏水氮浓度与前茬作物有关，草莓和蔬菜高，麦茬低，TN为5．73mg／L，渗漏负荷为22．92kg／hm^2，其中硝态氮占50％左右。稻田氮素总流失负荷占稻季化肥用量的13．23％。测坑和大田试验都证明，施用有机肥可较多地减少稻田氮素流失量。     

一体式膜生物反应器回用处理生活污水

将循环活性污泥系统(Cyclic Activated Sludge System,CASS)与膜过滤技术组合为一体式膜生物反应器(Submerged Membrane Bioreactor,SMBR),研究其用于生活污水回用处理的可行性,对该工艺的适宜运行条件进行了研究.结果表明,水力停留时间(HRT)为4 h、DO在2.0～3.5 mg/L、温度控制在常温、pH在6.5～8.0的运行条件是比较经济高效的.并考察了装置对实际生活污水的处理效果,结果表明出水水质优异,优于中水回用标准(CJ 25.1-89).     

臭氧化对垃圾填埋场后期渗滤液的预处理研究

应用自制微孔扩散式接触反应器,考察了不同pH条件下垃圾填埋场后期渗滤液的臭氧化预处理效果.结果表明,渗滤液初始pH值升高,臭氧利用率增大,垃圾渗滤液中COD、腐殖酸的去除速率加快;当初始pH为10时,经臭氧化处理120 min后,模拟废水的BOD5/COD可从初始的0.17提高到0.36,改善了废水的可生化性,同时渗滤液的色度、浊度、腐殖酸和SS也有较高的去除率.     

热带海水养殖清洁生产技术模式探讨

采用太阳光化学修复原理对典型热带地区--海南省某养殖场废水进行清洁闭环生态养殖技术初步探讨.采用现场定位观测实验研究方法,探讨高位池光化学循环净化装置对养殖废水中COD、SS等污染物的去除效应、脱氮解毒效应以及增氧效应等.结果表明,本实验装置能有效地实现热带地区高位池循环水养殖及养殖污水的"零排放",是满足环保要求的一种多功能、低成本、效果好的水体净化方法.     

危险废物的处理处置措施研究

危险废物因具有毒性、易燃性、腐蚀性、反应性和感染性等多种危害特性,如果暴露于环境中将会对生态环境和人类健康造成很大威胁;所以及时而有效地处理处置危险废物意义极为重大.文章简要地介绍了危险废物的定义及其来源,并指出其对环境和人类造成的危害,总结了我国目前的危险废物处理处置技术的现状,根据我国危险废物污染防治的技术路线和技术政策,分析了危险废物的处置措施,系统地论述了常规危险废物的常用处置方法,从而揭示了我国在危险废物处理处置方面及管理方面的问题,并提出针对危险废物处理处置的对策与建议.     

Functional soil organic matter fraction in response to short-term tillage management under the double-cropping rice paddy field in southern of China

Environmental Science and Pollution Research - Soil organic matter (SOM) and its fraction play an important role in maintaining and improving soil fertility of paddy field. However, there is still...