Partitioning and sources of PAHs in wastewater receiving streams of Tianjin,China

Polycyclic aromatic hydrocarbons (PAHs) partitioning among dissolved phase, suspended particulate matter, pore water, and sediment was studied in one moderately contaminated river (Yongding New River) and two highly contaminated drainage canals (South Drainage Canal and North Drainage Canal) of Tianjin, China. PAHs concentrations in sediment (ranged from 0.2 to 195 μg/g) showed positive relations with both total organic carbon contents (ranged from 0.7% to 31.1%, dw) and black carbon contents (ranged from 0.1% to 2.1%, dw) in the sediments. Moreover, most of the measured organic carbon normalized partition coefficients of PAHs in the three streams were 0.76 to 1.54 log units higher than the predicted values. These indicated that strong and nonlinear sorption of PAHs by carbonaceous geosorbents such as black carbon (BC) existed in the streams, and BC was an important part of the carbonaceous particles controlling the partitioning of PAHs in the sediments of this study. PAH component ratio analyses suggested that PAHs in the three streams, effluent samples from wastewater treatment plants, and soil samples by the riverbank had similar main sources, which is coal/petroleum combustion. We suggested the transportation and transformation of both carbonaceous particles and PAHs during wastewater treatment process, surface runoff, etc, should be studied further in order to make decisions on PAHs controlling measures.     

用稳健统计法处理方法标准验证实验中方法检出限数据

方法检出限是分析方法基本性能参数之一。根据《环境监测分析方法标准制修订技术导则》(HJ 168—2010)的要求,此参数需要6家以上实验室基于特定样品测试数据的标准偏差得到。目前,标准文本大多采用各家实验室方法检出限中最大值。研究提出用稳健统计法处理方法验证数据,无需识别和删去离群值,可将离群值的影响降到最小。基于4组公开发表数据和2组实测数据,比较了不同方法计算结果。结果表明:参与统计的3组数据29个检测项目中,常规方法确认的方法检出限被判为离群值占27.6%。取最大值存在数值偏高的风险。提出了用曼德尔k检验法识别1组方法检出限数据中的离群值,该方法同样可以用于实验室数据与标准文本中方法检出限符合性判断。     

Heavy metal speciation in various types of fly ash from municipal solid waste incinerator

Fly ash (FA) from municipal solid waste incinerators has been known as hazardous waste, which is mostly because of the high content of heavy metal and dioxins. Besides the content, the form of the heavy metals in fly ash is also very important, because it is tightly related with the leaching behavior of fly ash in diverse circumstances. To evaluate the environment potential risk of fly ash, the Tessier chemical extraction method was adopted. In this study, four kinds of fly ash were examined, one sample from China (CFA) and the other three from Japan (RFA, CaFA and NaFA). Five metal elements were detected and they were Ni, Cr, Cd, Pb, and Cu. The result of total heavy metals’ concentration showed CFA has the lowest content. As to the Tessier chemical extraction experiments, the results show that Cd, Pb, and Cu have higher leaching risk in the environment than other heavy metals. The result of leaching test experiment showed that the more exchangeable speciation of Cd, Cr and Pb in FA, the more it could leach out in natural environment.     

Evaluation of removal efficiency for acute toxicity and genotoxicity on zebrafish in anoxic–oxic process from selected municipal wastewater treatment plants

The anoxic–oxic (A/O) process has been extensively applied for simultaneous removal of organic contaminants and nitrogen in wastewater treatment. However, very little is known about its ability to remove toxic materials. Municipal wastewater contains various kinds of pollutants, some of which have recalcitrant genotoxicity and may cause potential threat to environment, and even can lead to extinction of many species. In this study, we have selected three municipal wastewater treatment plants (WWTPs) employing anoxic–oxic (A/O) process to evaluate their ability to remove acute toxicity and genotoxicity of wastewater. Mortality rate of zebrafish (Danio rerio) was used to evaluate acute toxicity, while micronucleus (MN) and comet assays were used to detect genotoxicity. Results showed that in this process the acute toxicity was completely removed as the treatment proceeded along with decrease in chemical oxygen demand (COD) (<50 mg L^?1) in the effluent. However, in these treatment processes the genotoxicity was not significantly reduced, but an increase in genotoxicity was observed. Both MN and comet assays showed similar results. The eliminated effluent may pose genotoxic threaten although its COD level has met the Chinese Sewage Discharge Standard. This study suggests that further treatment of the wastewater is required after the A/O process to remove the genotoxicity and minimize the ecotoxicological risk.     

FeⅡ(EDTA)协同生物转鼓过滤器去除NO的实验研究

采用自行研制的生物转鼓反应器(RDB)处理难溶于水的NO废气,为提高NO的传质系数和去除效率,实验考察了营养液中添加FeⅡ(EDTA)络合剂协同RDB以提高NO去除效率的过程.结果表明,当空床停留时间(EBRT)为0.96 min时,在营养液中添加FeⅡ(EDTA)至100mg/L后,NO的去除效率从70.78%升至7...     

催化裂化钠碱脱硫液中钙镁离子的去除

研究了化学沉淀法和氨基膦酸型螯合树脂吸附法对催化裂化钠碱脱硫液中Ca~(2+)和Mg~(2+)的去除效果。实验结果表明:NaOH沉淀法可有效去除钠碱脱硫液中的Mg~(2+),当溶液pH为12、反应时间为15 min时,Mg~(2+)去除率达91.6%;NaOH-Na_2CO_3联合沉淀法无法去除钠碱脱硫液中的Ca~(2+);经过NaOH溶液有效除Mg~(2+)后的脱硫液再采用氨基膦酸型螯合树脂吸附柱去除其中的Ca~(2+)和Mg~(2+),可使出水硬度小于2 mg/L。提高进水pH、降低进水流量、降低进水硬度均可提高单位体积树脂的处理水量。     

市场分割对长江经济带能源环境效率影响研究

基于要素资源配置效应、技术创新效应和竞争效应,本文梳理了市场分割对长江经济带能源环境效率的影响机制,基于省际面板数据实证检验,发现:长江经济带能源环境效率随着市场分割程度存在显著倒"U"形关系;在规模报酬递减作用下,市场分割对长江经济带能源环境效率的影响从提升转变为抑制。未来破除长江经济带能源环境效率提升瓶颈的关键在于研发投入、对外开放水平以及市场融合。另外,分样本回归表明市场分割导致长江经济带中游地区能源环境效率存在"中部塌陷"的风险。由此,加强研发资金的精准投入、提升对外开放度和中游地区支撑力,以及增强长江经济带生态协同是长江经济带提升能源环境效率的重要突破口。     

气相分子吸收光谱法测定水中氨氮干扰因素的研究

气相分子吸收光谱法测定成分复杂氨氮实际样品时,干扰因素造成测定结果不准确,而现有的标准方法和文献对干扰物质的研究不全面,制约了仪器的应用。该文系统地开展干扰因素的研究,提出干扰因素的消除方法,用加标回收率验证消除的有效性。结果表明,亚硫酸盐、硫化物等还原性物质对测定产生负干扰;石油烃、N,N-二甲基甲酰胺(DMF)等挥发性有机物、有机胺类以及亚硝酸盐对测定产生正干扰。根据不同干扰类型,通过加入适量酸性重铬酸钾溶液、在酸性条件下加热煮沸、预蒸馏等方法可消除干扰,消除干扰后加标回收率为84%~120%。生活污水、石化企业废水等6种典型水样消除干扰后,气相分子吸收光谱法和纳氏试剂分光光度法测定氨氮有较好的可比性,干扰消除方式有效。