Improvement of sludge dewaterability with modified cinder via affecting EPS

The relationship between the improvement of sludge dewaterability and variation of organic matters has been studied in the process of sludge pre-conditioning with modified cinder, especially for extracellular polymeric substances (EPS) in the sludge. During the conditioning process, the decreases of total organic carbon (TOC) and soluble chemical oxygen demand (SCOD) were obviously in the supernatant especially for the acid modified cinder (ACMC), which could be attributed to the processes of adsorption and sweeping. The reduction of polysaccharide and protein in supernatant indicated that ACMC might adsorb EPS so that the tightly bound EPS (TB-EPS) decreased in sludge. In the case of ACMC addition with 24 g·L^–1, SRF of the sludge decreased from 7.85 × 10¹² m·kg^–1 to 2.06 × 10¹² m·kg^–1, and the filter cake moisture decreased from 85% to 60%. The reconstruction of “floc mass” was confirmed as the main sludge conditioning mechanism. ACMC promoted the dewatering performance through the charge neutralization and adsorption bridging with the negative EPS, and provided firm and dense structure for sludge floc as skeleton builder. The passages for water quick transmitting were built to avoid collapsing during the high-pressure process.

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乐果对秀丽隐杆线虫生活史特征的影响

采用一种半流体培养基"挂滴法"对线虫进行培养和生命表实验,研究了低剂量暴露下乐果对秀丽隐杆线虫生活史特征的影响。在半致死浓度1/10 LC50、1/100 LC50、1/1000 LC50暴露剂量下(分别为7、0.7、0.07 mmol·L-1)染毒4 h。结果表明,0.7和7 mmol·L-1暴露组线虫的总繁殖率(TFR)分别为260.60、203.80,明显低于对照组(299.23,P0.05);净增殖率(R0)分别为240.29、147.67,明显低于对照组(298.67,P0.05);内禀增长率(rm)分别为1.342 d-1、1.233 d-1,明显低于对照组(1.387 d-1,P0.05);而0.07 mmol·L-1暴露组线虫的总繁殖率为293.84,净增殖率为286.60,与对照组比差异都没有统计学意义(P0.05)。在上述浓度范围,线虫的总繁殖率(TFR)、净增殖率(R0)和内禀增长率(rm)都随乐果浓度的升高而降低,并存在剂量效应关系。研究同时发现0.07 mmol·L-1暴露组线虫的内禀增长率为1.405 d-1,明显高于对照组(P0.05)。研究结论认为一定剂量的乐果使线虫的繁殖力降低;而低剂量暴露则对内禀增长率具有毒物兴奋效应。本文选择的3个指标TFR、R0、rm对低剂量下乐果暴露的响应敏感。     

混凝-超滤处理径流雨水效果——以华南地区为例

采用超滤膜(UF)为核心,以混凝作为预处理措施,对混凝-超滤工艺处理径流雨水的特性和膜通量变化与污染现象进行了研究,并对聚合硫酸铁(PFS)单独混凝、UF、PFS-UF组合工艺进行了对比;在优化混凝基础上,考察了混凝-UF对常规水质指标及总磷、生物可同化有机碳(AOC)、可生物降解溶解性有机碳(BDOC)等生物稳定性指标的去除效果.结果表明,混凝可有效去除TOC、UV254和总磷,混凝剂投加量与污染物去除近似呈线性关系.各混凝剂除浊效能均良好.综合考虑混凝处理效率与经济性,实验采用混凝方案为10 mg·L-1的PFS.PFS、UF、PFS-UF工艺除浊率均在95%以上,PFS和UF对TOC和UV254的去除较为接近,采用PFS-UF可提高去除率13%—15%;PFS-UF处理后雨水的AOC、BDOC分别降低至61.8μg·L-1、0.19 mg·L-1,残余总磷可降至3.8μg·L-1,雨水生物稳定性明显提高.PFS、UF和PFS-UF对颗粒物的去除率分别达80.5%、99.6%和99.9%.膜通量的变化和SEM图分析表明,混凝在一定程度上减轻了UF膜污染;形成的凝胶层具有一定整体强度,水力清洗时易于清除,膜通量恢复较好;但同时凝胶层的产生也增大了透膜阻力,PFS-UF工艺的周期内膜通量衰减有增加的趋势.     

典型环境内分泌干扰物的来源、环境分布和主要环境过程

内分泌干扰物(EDCs)作为一种新兴污染物,具有憎水性、低剂量效应和半衰期长等特征,在全球的土壤/沉积物中已被广泛检测到,并发现已给环境带来了严重的威胁。本文重点综合评述了近10年来土壤/沉积物中EDCs的来源、浓度水平、空间分布及吸附特性的研究。结果发现,EDCs来源涉及农业、工业和生活等多个方面;空间分布上,一般呈近海地区沉积物中EDCs浓度水平较河流底泥及土壤低,而高度工业化、城市化地区土壤/沉积物中EDCs浓度亦较高;EDCs的吸附受土壤/沉积物理化性质、EDCs自身性质和环境条件的共同影响,一般土壤有机质的含量和成熟度、土壤颗粒的比表面积与其吸附能力呈正相关,黏土矿物类型对EDCs的吸附也有重要的影响;EDCs的吸附能力与其自身的疏水性和结构特征有关;温度升高和溶液p H值增加都不利于EDCs的吸附,而溶液离子强度的增加对其吸附起着促进作用。土壤/沉积物对EDCs的吸附是一个复杂的过程,因此对其吸附特性需要进一步的探讨。     

Microprofiles of activated sludge aggregates using microelectrodes in completely autotrophic nitrogen removal over nitrite (CANON) reactor

Microsensor measurements and fluorescence in situ hybridization (FISH) analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor (SBR) for completely autotrophic nitrogen removal over nitrite (CANON). Fed with synthetic wastewater rich in ammonia, the SBR removed 82.5±5.4% of influent nitrogen and a maximum nitrogen-removal rate of 0.52 kgN·m⁻³·d⁻¹ was achieved. The FISH analysis revealed that aerobic ammonium-oxidizing bacteria (AerAOB) Nitrosomonas and anaerobic ammonium-oxidizing bacteria (AnAOB) dominated the community. To quantify the microbial activities inside the sludge aggregates, microprofiles were measured using pH, dissolved oxygen (DO), NH4+, NO2− and NO3− microelectrodes. In the outer layer of sludge aggregates (0–700 μm), nitrite-oxidizing bacteria (NOB) showed high activity with 4.1 μmol·cm⁻³·h⁻¹ of maximum nitrate production rate under the condition of DO concentration higher than 3.3 mg·L⁻¹. Maximum AerAOB activity was detected in the middle layer (depths around 1700 μm) where DO concentration was 1.1 mg·L⁻¹. In the inner layer (2200–3500 μm), where DO concentration was below 0.9 mg·L⁻¹, AnAOB activity was detected. We thus showed that information obtained from microscopic views can be helpful in optimizing the SBR performance.     

Occurrence and dominance of Cylindrospermopsis raciborskii and dissolved cylindrospermopsin in urban reservoirs used for drinking water supply,South China

The tropical cyanobacterium Cylindrospermopsis raciborskii is of particular concern for its invasive characteristics and production of the toxin cylindrospermopsin (CYN). The present study represents the first attempt to determine the distribution of C. raciborskii and CYN in tropical China. The presence of C. raciborskii and CYN, as well as the composition of phytoplankton, was determined from a total of 86 samples from 25 urban reservoirs for drinking water supply in Dongguan City of South China. The presence of C. raciborskii was observed in 21 of the 25 reservoirs and confirmed that this species has been widely distributed in the investigated reservoirs. C. raciborskii accounted for between 0.1 and 90.3 % of the total phytoplankton biomass and contributed to the majority of the phytoplankton in some reservoirs such as Tangkengbian and Xiagongyan. Its biomass was negatively correlated with NO₃ ^?-N concentration and Secchi depth. Dissolved CYN was detected in more than one-half of the reservoirs with concentrations up to 8.25 μg L^?1, and it positively correlated with C. raciborskii biomass. Dissolved microcystins (MCs) were detected in 12 of the 25 reservoirs with a maximum concentration 1.99 μg L^?1. Our data strongly suggest that C. raciborskii and CYN could be important health hazards in urban reservoirs of South China and that more data are needed for further assessment.     

燃煤电厂煤中汞含量对烟气中汞排放水平的影响

对江苏省9家燃煤电厂入炉煤中ω（汞）及烟气中ρ（汞）进行了测试,结果表明,9家燃煤电厂入炉煤中ω（汞）为54．5～297 ng／g,平均值为139 ng／g,低于我国煤中ω（汞）的平均值（220 ng／g）。燃煤电厂排放烟气中ρ（汞）为0．08～16．97μg／m^3,远低于《火电厂大气污染物排放标准》（GB 13223－2011）汞及其化合物标准限值（30μg／m^3）。通过对燃煤电厂入炉煤中ω（汞）与最终排放的烟气中ρ（汞）进行分析,两者之间有一定的相关性。     

Mobilization and plant accumulation of prometryne in soil by two different sources of organic matter

Prometryne is a selective herbicide of the s-triazine chemical family. Due to its weak absorption onto soil, it readily leaches down through the soil and contaminates underground water. Application of organic manure to soil has become a widespread practice as a disposal strategy to improve soil properties. In this study, we demonstrated the effect of pig manure compost (PMC) and lake-bed sludge (SL) on the sorption/desorption, mobility and bioavailability of prometryne in soil using comprehensive analysis approaches. Downward movement of prometryne was monitored in the packed soil column. Addition of PMC or SL decreased considerably the mobility and total concentration of prometryne in the soil leachate. Bioavailability analyses with wheat plants revealed that addition of the organic matter reduced accumulation of prometryne in tissues and increased plant elongation and biomass. These results indicate that the organic amendments are effective in modifying adsorption and mobility of the pesticide in soil.     

基于3G网络平台的环保移动执法系统构建

从当前环保现场执法所面临的手段落后、执法尺度不一等实际问题出发,构建了一套依托于3G无线通信平台的移动执法系统。该系统采用先进的网络通讯技术,借助执法终端PDA手机,可实现在执法现场实时查询环保动、静态信息,录入、打印检查笔录及执法表单等功能,实现环保监察部门统一执法、规范执法流程、提高执法效率的最终目标。     

汉丹江(陕西段)水质变化特征分析

基于2008—2012年陕西省境内汉江、丹江干流14个断面的水质监测数据,采用单因子评价法、平均综合污染指数法和秩相关系数法等对该段水体的水质变化特征进行研究。结果表明,汉丹江(陕西段)断面水质以Ⅱ类、Ⅲ类为主,水质总体为优;水质综合污染状况呈下降趋势,其中汉江下降趋势显著;水质综合污染状况空间差异和区域分布特征明显,城区段污染大于郊区,各行政区段河流下游污染大于上游。流域水质主要受有机污染和营养盐因子影响,水体污染源主要来自城镇生活源和农业面源,工业源占比不大且排放行业较为集中。