Nitrate Dynamics in Two Streams Impacted by Wastewater Treatment Plant Discharge: Point Sources or Sinks?

We examined nitrate processing in headwater stream reaches downstream of two wastewater treatment plant outfalls during low streamflow. Our objectives were to quantify nitrate mass flux before and after effluent discharge and to use field and laboratory techniques to assess the mechanism of nitrate uptake. Microcosm experiments were utilized to determine the location of nitrate processing, and molecular biomarkers were used to detect and quantify microbial denitrification. At one site, downstream nitrate mass flux was significantly (p = 0.01) lower than sum of upstream and wastewater effluent fluxes, indicating rapid stream assimilation of incoming nitrate in the vicinity of the point source. Microcosm experiments supported the theory that nitrate processing occurs in sediments. Molecular assays for denitrifcation‐associated functional genes nosZ, nirS, and nirK, provided evidence that effluent contained enriched denitrifying communities relative to ambient stream water. Nitrate loss at the site with greater uptake was correlated with sulfate loss (p < 0.01; r² = 0.86), suggesting a possible link between sulfate reducing bacteria and denitrifying bacterial communities. Results suggest there is an opportunity to better understand nitrate dynamics in cases where point sources may act as point sinks under specific sets of conditions.     

大型养猪场生物发酵舍污水零排放工程的管理

针对生物发酵零排放猪舍技术在实际应用中存在的主要问题,指出科学管理是零排放生物发酵舍技术应用的关键因素,同时要注重室外发酵床的建设和管理,注重循环利用以延长产业链,加强新技术新产品的研发。     

生物酶催化技术应用于卡拉胶废水处理工程

卡拉胶废水成分复杂,含有难生化降解的有机污染物种类多,且浓度高,碱性大,含盐量高,按现有的处理工艺,很难达到排放标准。本文以福建省石狮市中科海藻制品发展有限公司卡拉胶废水处理工程为例,阐述了生物酶催化技术在卡拉胶废水处理中的应用。通过在生化系统建立酶体系,利用生物酶催化作用,提高废水中难降解有机物的可生化性与可处理性,从而使出水达到《污水综合排放标准》(GB8978—1996)规定的一级排放标准。     

Crop Discharge Permits for Reduction of Nitrogen Loads to the Baltic Sea1

Collentine, Dennis and Holger Johnsson, 2011. Crop Discharge Permits for Reduction of Nitrogen Loads to the Baltic Sea. Journal of the American Water Resources Association (JAWRA) 48(1): 24‐31. DOI: 10.1111/j.1752‐1688.2011.00596.x Abstract: Current international agreements call for a significant reduction of nutrient loads to the Baltic Sea. In one of the signatory countries, Sweden, regulatory authorities have concluded that new measures will be needed to meet national reduction targets. This article evaluates the effect of one possible new measure for reducing nitrogen loads, introducing mandatory discharge permits for crop cultivation as one component of a proposed discharge permit system. Using the framework of the proposed system, expected net load reductions and permit prices are calculated for three crop permit scenarios in a catchment in Southern Sweden. In addition, gross leaching is calculated for a larger region to study the potential for reducing net loads. The article concludes that while permitting reduces loading, achieving reduction targets will require additional measures beyond the scenarios studied.     

Optimizing Bankfull Discharge and Hydraulic Geometry Relations for Streams in New York State1

Mulvihill, Christiane I. and Barry P. Baldigo, 2012. Optimizing Bankfull Discharge and Hydraulic Geometry Relations for Streams in New York State. Journal of the American Water Resources Association (JAWRA) 48(3): 449-463. DOI: 10.1111/j.1752-1688.2011.00623.x Abstract: This study analyzes how various data stratification schemes can be used to optimize the accuracy and utility of regional hydraulic geometry (HG) models of bankfull discharge, width, depth, and cross-sectional area for streams in New York. Topographic surveys and discharge records from 281 cross sections at 82 gaging stations with drainage areas of 0.52-396 square miles were used to create log-log regressions of region-based relations between bankfull HG metrics and drainage area. The success with which regional models distinguished unique bankfull discharge and HG patterns was assessed by comparing each regional model to those for all other regions and a pooled statewide model. Gages were also stratified (grouped) by mean annual runoff (MAR), Rosgen stream type, and water-surface slope to test if these models were better predictors of HG to drainage area relations. Bankfull discharge models for Regions 4 and 7 were outside the 95% confidence interval bands of the statewide model, and bankfull width, depth, and cross-sectional area models for Region 3 differed significantly (p < 0.05) from those of other regions. This study found that statewide relations between drainage area and HG were strongest when data were stratified by hydrologic region, but that co-variable models could yield more accurate HG estimates in some local regional curve applications.     

气相沿面放电—活性炭纤维吸附联合降解双酚A废水研究

利用气相沿面放电—活性炭纤维(ACF)吸附(简称放电—吸附)联合处理含双酚A(BPA)废水,探讨了联合处理对BPA的降解效果,并通过处理过程中O3利用率变化以及处理前后ACF的表观状态变化分析了反应的作用机制。结果表明,放电—吸附联合处理相比单独放电和单独ACF吸附能显著提高BPA的降解率;在一定范围内,加大放电电压能提高放电—吸附联合处理的BPA降解效果,但放电电压超过一定值后,放电产生的O3量进一步增多,对ACF表面的结构破坏作用增加,反而导致BPA的降解效果降低,本研究较佳的放电电压为8.5kV;扫描电镜分析结果表明,经放电—吸附联合处理后,ACF表面出现大量的孔道,提高了表面的BPA富集浓度,同时也增加反应的活性位点;傅里叶变换红外光谱分析结果表明,联合处理后ACF表面的C—O、C=C、O—H等官能团都有所减少,可能是联合处理过程中O3等活性物质与ACF表面的这些还原性官能团发生了反应,诱导O3分解出了更多的自由基,从而促进了BPA的降解。     

加药量和水力搅拌速度对雨水混凝效果的影响

为降低分流制雨水中悬浮颗粒物及其他污染物浓度,减轻城市景观河道的水体富营养化程度,对取自泵站的雨水进行混凝沉淀工艺优化实验。以PAC为混凝剂,采用Zeta电位仪、激光粒度仪和iPDA在线监测技术对混凝过程进行监测,考察了混凝剂投加量和水力搅拌速度对絮体形成和分流制雨水处理效果的影响,结果表明,混凝剂投加量和混合水力搅拌速度直接影响絮体Zeta电位和聚沉特性;混合搅拌速度控制混凝反应速率,絮凝速度梯度影响絮体形成粒径。FI曲线特征参数对控制混凝工艺具有指导意义。PAC投加量为35 mg/L,混合阶段搅拌速度800 r/min,搅拌30 s,絮凝阶段采用150、108和60 r/min的转速各自搅拌5 min,沉后水中剩余颗粒总数最少,浊度、COD和总磷去除效果最佳。     

高频脉冲介质阻挡放电去除水中17β-雌二醇

实验采用高频脉冲介质阻挡放电工艺处理水体中的17β-雌二醇（E2）。结果表明,该工艺可以有效地降解水中的E2,E2的降解过程符合一级反应动力学模型。当体系脉冲峰-峰电压为24kV,初始浓度为100μg／L的E2在超纯水中的降解一级反应速率常数为0．1314min^-1。E2的降解速率常数随脉冲峰-峰电压的增大而升高,随E2初始浓度和溶液初始pH增加而降低,溶液初始电导率对E2的降解影响不大。     

国内外造纸行业水污染排放标准比较研究

中国是造纸大国,制浆造纸在中国属于重污染行业。2008年国家发布的《制浆造纸工业水污染物排放标准》对整个行业可能排放的污染物提出了要求。本文通过将该标准与国外造纸行业相关的水污染物排放标准进行比较研究,找出我国标准与国外的差别,并为完善我国造纸行业水污染物排放标准提出建议。     

修复铬污染地下水的可渗透反应墙介质筛选

通过实验研究筛选出一种经济、高效的用于修复铬污染地下水的可渗透反应墙(PRB)介质。实验以铬污染地下水为研究对象,分别对Fe0、Fe0+石英砂和包覆型零价铁填料进行了筛选实验,选取处理效果好且经济可行的包覆型零价铁材料作为PRB反应介质。结果表明,以包覆型零价铁材料作为PRB反应介质,大大提高了铁粉的利用效率,且缓解了系统堵塞严重的问题。以包覆型零价铁材料作为PRB反应介质修复Cr(VI)污染地下水是可行的。