Evaluation of rural wastewater treatment processes in a county of eastern China

With the rapid urbanization and industrialization in China, wastewater treatment in rural areas has become an increasing national concern. The selection of appropriate treatment processes closely based on the actual local status is crucial for the prevention of water quality deterioration in rural areas of China. This study presents a full year survey on the performances of various rural wastewater treatment processes at a county level in eastern China including seven three-chamber septic tanks (ST), five micro-power biological facilities (MP), seven constructed wetlands (CW), three stabilization ponds (SP) and five centralized activated sludge treatment plants (AS). It was found that although ST could remove a notable portion of total suspended solids (TSS) and chemical oxygen demand (COD(Cr)), it was ineffective in reducing nutrients and pathogens. Reliability and stability analyses showed that the centralized AS and decentralized CW processes outperformed the SP and MP processes. There were obvious discrepancies between the mean design concentrations, which ensure that 95% of the effluents meet the discharge standards, and the actual effluent concentrations determined for each process. The expected compliance with the tentatively adopted second-grade discharge standards (GB 18918-2002) was unsatisfactory for most of the water quality parameters examined, indicating an urgent need to design more practical discharge standards for decentralized treatment processes. Based on an overall assessment of reliability, stability and cost-effectiveness, the centralized AS was suitable for densely populated towns while the decentralized CW was suitable for sparsely populated villages.     

珠三角地区造纸行业排水中二 NFDA1 英(PCDD/Fs)特征分析

研究采用¹³C同位素内标稀释定量法,高分辨气相色谱质谱法(HRGC-HRMS)对珠三角地区造纸行业排水中PCDD/Fs特征进行了分析。结果表明,该地区造纸行业PCDD/Fs含量为:4.75~80.05 pg/L,且以OCDD占主导地位;同时该类行业PCDD/Fs的TEQ为:0.21~2.02 pg TEQ/L。最后通过对该类行业排水中PCDD/Fs的TEQ年排放量进行讨论,其结果为0.30~12.97 mg TEQ,且年平均排放量(4.42 mgTEQ)只占我国造纸行业TEQ总排放量的很小一部分。     

构建覆盖国家环境监测网的质量控制体系

"十二五"期间,中国将全面完成国家环境监测网的布局与建设,环境管理将开始由以环境污染控制为目标导向,向以环境质量改善为目标导向转变,以全面考核空气、水环境和土壤等环境质量的新环境管理时代即将来临。从现有环境监测质控体系所发挥的作用、存在的问题以及环境管理的需求出发,提出构建覆盖国家环境监测网的质量控制体系,论述各级环境监测站的质控职责,尤其是省级监测站作为地区质量控制中心,应该和国家站一起加大自身质控能力建设,为提高环境监测数据的可信度做好质控工作。     

Factor analysis of H2S emission at a wastewater lift station: a case study

Odor and corrosion are common problems in domestic wastewater collection, transportation, pumping, and treatment processes. Based on the comparison among odorous compounds and onsite observations at a wastewater lift station, H₂S is more likely to have caused the odor and corrosion problems than methanethiol and other organic sulfides. The field data from both air and wastewater quality monitoring demonstrated that more H₂S (1 ppmv) was formed at a more negative redox potential, lower pH, and a higher temperature of wastewater. Since the lower detection level of most current analytical techniques is much greater than human’s smell and the reference concentration for adverse health effects, automatic monitoring on the threshold of H₂S formation provides a mechanism to trigger control techniques only when necessary for cost saving purposes. Based on Gibbs free energy, a more negative redox potential is required to form H₂S with an increase in pH and a decrease in temperature and SO ₄ ^2? concentration. However, pH effect is more significant than both temperature and SO ₄ ^2? concentration for H₂S formation. It is recommended that H₂S control techniques be started when the redox potential is below ?44 mV, the pH is lower than 5.6, and the temperature is higher than 11.5 °C to control H₂S below the reference concentration. Corroded concrete particles were examined by X-ray diffraction, which showed that the dominant crystal form was quartz.     

Sensitivity of isolated eggs of pond snails: a new method for toxicity assays and risk assessment

The concentration of heavy metals in the environment is normally low. We here address whether using the development of isolated pond snail Radix auricularia eggs would provide a more sensitive endpoint and whether the gelatinous matrix of the egg mass surrounding the eggs indeed protects the snail embryos. In the present study, artificial removal of the gelatinous matrix of egg masses greatly increased the sensitivity of developing eggs to a heavy metal (cadmium). The sensitivity of isolated eggs to cadmium was determined using several convenient endpoints, including mortality, hatching rate, and heart rate, with an acute toxicity test and a subchronic test. In the acute toxicity test, a 96-h LC₅₀ value of 58.26 μg/L cadmium was determined. In the subchronic toxicity test, sublethal effects in terms of a significant reduction in hatching rate could be found in the 25-μg/L treatment, and a significant decrease of heart rate was observed in both treatments (5 and 25 μg/L). The high sensitivity of isolated eggs indicates that such tests can be efficient for toxicity assays and risk assessment, although one needs to keep in mind that the ecologically relevant measure of toxicity will be how eggs are affected when they are still inside the egg mass.     

集合数值预报系统在上海市空气质量预测预报中的应用研究

介绍了上海市世博环境空气质量集合数值预报系统的框架,分析了各模式在上海市空气质量预报及排放源污染贡献测算中的应用情况,提出开发多种预报手段、实施集合预报是提高城市空气质量预报准确率的发展方向。     

重庆市住宅楼环境电磁辐射的初步测量与分析

初步探测重庆市住宅楼环境电磁辐射的现状及其影响因素,为建立人居环境电磁场特征数据库提供依据。按照国家标准的要求和方法,在重庆市选择4个典型居住小区,分别测量各小区住宅楼不同楼层电梯门口或楼梯间以及各住宅楼楼顶的电磁辐射水平,结果表明,本次横断面调查中,在1MHz～40GHz频段,各栋楼的综合场强为17.13～17.18V/m,已接近GB 8702-88《电磁辐射防护规定》的公众照射导出限值,各楼层间差异无统计学意义(P>0.05)。在5～1000Hz频段,各栋楼楼内综合场强分布差异无统计学意义(P>0.05),而临近高压线的住宅楼楼顶综合场强明显高于其他小区楼顶以及同一栋楼其他楼层的综合场强(P<0.05),并且该楼各楼层的磁场强度明显高于其他住宅楼(P<0.05)。所测住宅楼的环境电磁辐射水平未超出国家相应标准限制,不同楼层电磁辐射水平与极低频辐射源的分布有关。     

Characterization of the monthly variation in (1 → 3)-β-d-glucan concentrations in university laboratories

We characterize the monthly variation in (1 → 3)-β-d-glucan concentration measured over the course of 1 year, and we evaluate the characteristics of size selection using a two-stage cyclone sampler. The (1 → 3)-β-d-glucan concentrations were measured in four bio-related laboratories. A total of 156 samples were collected using a new two-stage cyclone sampler. Analysis of (1 → 3)-β-d-glucan was performed using the kinetic Limulus amebocyte lysate assay. The study showed that airborne (1 → 3)-β-d-glucan concentrations were significantly higher in laboratory D (mean ± SD 1,105?±?1,893 pg/m³) and in the spring (5,458 pg/m³). The highest concentration of (1 → 3)-β-d-glucan occurred in the spring, particularly in May.     

电解铝企业阳极残渣、阳极残极浸出毒性鉴别及管理建议

对电解铝企业产生的阳极残渣、阳极残极浸出毒性进行了鉴别。鉴别结果表明：电解铝企业产生阳极残渣浸出液中氟化物（不含氟化钙）平均质量浓度为140 mg／L,最高达244 mg／L,且超标试样数达到《危险废物鉴别标准浸出毒性鉴别》中相应规定,鉴别该废物属于危险废物,应按照危险废物进行管理;阳极残极浸出液中氟化物（不含氟化钙）平均质量浓度为74 mg／L,无超标试样数,该废物不属于具有氟化物浸出毒性的固体废物,建议仍按一般固体废物进行管理。