Urban stream temperature patterns: Spatial and temporal heterogeneity in the Philadelphia region,Pennsylvania, USA

Stream temperature is a critical water quality parameter that is not fully understood, particularly in urban areas. This study explores drivers contributing to stream temperature variability within an urban system, at 21 sites within the Philadelphia region, Pennsylvania, USA. A comprehensive set of temperature metrics were evaluated, including temperature sensitivity, daily maximum temperatures, time >20°C, and temperature surges during storms. Wastewater treatment plants (WWTPs) were the strongest driver of downstream temperature variability along 32 km in Wissahickon Creek. WWTP effluent temperature controlled local (1–3 km downstream) temperatures year-round, but the impacts varied seasonally: during winter, local warming of 2–7°C was consistently observed, while local cooling up to 1°C occurred during summer. Summer cooling and winter warming were detected up to 12 km downstream of a WWTP. Comparing effects from different WWTPs provided guidelines for mitigating their thermal impact; WWTPs that discharged into larger streams, had cooler effluent, or had lower discharge had less effect on stream temperatures. Comparing thermal regimes in four urban headwater streams, sites with more local riparian canopy had cooler maximum temperatures by up to 1.5°C, had lower temperature sensitivity, and spent less time at high temperatures, although mean temperatures were unaffected. Watershed-scale impervious area was associated with increased surge frequency and magnitude at headwater sites, but most storms did not result in a surge and most surges had a low magnitude. These results suggest that maintaining or restoring riparian canopy in urban settings will have a larger impact on stream temperatures than stormwater management that treats impervious area. Mitigation efforts may be most impactful at urban headwater sites, which are particularly vulnerable to stream temperature disruptions. It is vital that stream temperature impacts are considered when planning stormwater management or stream restoration projects, and the appropriate metrics need to be considered when assessing impacts.     

Electrocoagulation/Electroflotation Process for Removal of Organics and Microplastics in Laundry Wastewater

In the present research, laundry wastewater treatment is studied using the electrocoagulation/electroflotation process. For the optimization of treatment conditions such as electrode type (Al–Al, Al–Fe, Fe–Fe, and Fe–Al), initial pH (5–9), current (0.54–2.16 A), and application time (15–60 min), response surface methodology is used. Removal efficiencies of chemical oxygen demand (COD), color, anionic surfactant, microplastic, and phosphate are studied. It is determined that the most effective removal is obtained with 2.16 A current, pH 9, and 60 min reaction time using Fe–Al electrode. Here, 91%, 94%, 100%, and 98% removal efficiencies are achieved for COD, surfactant, color, and microplastic, respectively. The operating cost of the combined process is calculated as $1.32 m^?3 for the optimum removal parameters. The adsorption kinetics study shows that the removal follows second‐order kinetics. The laboratory‐scale test results indicate that the electrocoagulation/electroflotation process is feasible for the treatment of laundry wastewater.     

盐度对废水生物处理的影响

研究了废水中不同含盐量对生化处理效果以及生物学变化规律的影响。在废水含盐量低于22g／L时,废水生化处理系统对COD的去除率可稳定在70％左右,污泥活性良好;随着进水盐浓度的增加,含盐量达到22g／L时,污泥活性开始受到抑制,COD去除率急剧下降到50％左右;当废水含盐量达到31g／L时,污泥活性明显受到抑制,污泥絮体开始部分解体,COD去除率下降到40％左右。     

纤维滤池在石化废水深度处理中的应用

针对华锦集团废水处理及回用工程采用纤维滤池深度处理化工混合废水技术,使其出水达到《城镇污水处理厂污染物排放标准》(GB18918—2002)一级A排放标准,研究主要对纤维滤池的原理、设计参数、运行效果等进行实践探讨。运行结果表明:在稳定运行阶段,可实现进水量2 100 m3/h。进水化学需氧量(CODCr)平均浓度为50 mg/L,悬浮物(SS)浓度为15 mg/L,浊度平均浓度为15 mg/L,处理出水CODCr≤30 mg/L、SS≤10 mg/L、浊度≤10 mg/L。该工艺处理效果稳定,对SS和浊度处理效果显著。     

波阻抗遗传算法反演方法的研究及应用

作者介绍的遗传算法是在自然界生物遗传过程优选和进化原理的基础上，针对波阻抗反演的实际问题，对标准的遗传算法进行了改进，引入了模拟退火算法中的热槽法控制初始群体的产生，用逐位迭代的交换方式代替传统的杂交方式即随机选择杂交点进行交换。使用改进的遗传算法对地震波阻抗进行反演，可很好地提高反演的精度。在文中最后，作者通过理论模型和实例验证了上述的思想。     

人工湿地污水处理技术及其在东平湖水质净化中的运用

人工湿地具有独特的净污机理和功能，日益受到全球的重视。通过综合国内外研究现状，分析了人工湿地污水处理技术的发展现状和趋势，认为人工湿地在我国具有广阔发展前景，尤其在重大调水工程及湖泊、河流水体污染防治等方面的应用。同时，探讨了如何利用人工湿地来解决南水北调东线工程关键枢纽——东平湖的水质问题，对东平湖人工湿地的建设地点、处理系统和净污植物类型进行了初步研究，提出了运用过程中需要注意的问题。     

南充市人工湿地的规划研究

通过对传统污水处理的生化二级处理系统与人工湿地污水处理系统分析和比较，可以看出污水处理厂具有投资大、运行成本费高、并难以解决水质“富营养化”的缺点，而人工湿地污水处理系统具有投资少、运行成本低、出水质量好的优点。根据南充城市化进程的具体形势，提出在规划和建设生态城市方案中，建设人工湿地污水处理系统的设想，并就人工湿地的规模、区位选择、活水公园设计、预期效益分析等问题进行了详细的论证和阐述。     

金属矿物材料在废水处理中的应用

从环境矿物学角度，对金属矿物材料(铁氧化物与氢氧化物、锰氧化物和氢氧化物、铁硫化物)在废水处理中的应用现状进行了综述，分析金属矿物材料在水环境保护方面存在的问题，并对其应用前景进行展望。     

人工湿地中植物的作用

近20 a来,人工湿地系统由于具有独特的净化机理和功能而越来越多地被用于处理生活污水、工业废水和农业污水。人工湿地系统之所以受到国际上广泛的关注,这是由于它具有低能耗,低成本,运行费用少和操作简便等优势。湿地植物在人工湿地中起着非常重要的作用,不但可以直接摄取和利用污水中的营养物质、吸收富集污水中的重金属等有毒有害物质;而且还能输送氧气到根区,提供根区微生物生长、繁殖和降解过程中对氧的需求。通过详细阐述植物对水中营养元素的吸收作用,说明了植物在人工湿地处理污水中的重要性,并提出了一些改进人工湿地处理污水能力的设想以及人工湿地系统水生植物有待进一步研究的问题,研究结果可以为进一步优化人工湿地系统的设计提供参考。     

Impacts of wastewater irrigation on soils and crops in suburban area of Shiraz, Iran

This preliminary work reported here dealt with potential impacts of wastewater irrigation on soils and crops sampled along the Koshk River canal in the suburban area of Shiraz City, Iran. It also attempts to assess the extent of heavy metal contamination in soils and crops and human exposure risk. For this purpose, samples including soils and plants were collected from two wastewater irrigated sites and a tubewell-irrigated site （marked by A, B and C）. Concentrations of the six heavy metals Ni, Pb, Cd, Zn, Cr and Cu were determined by AAS. Physical and chemical properties of soil samples were also determined. The PLIs and CF for soils and HQ （Hazard quotient） for some vegetables were calculated. The results showed that organic matter content increased from 22% to 30 % in wastewater-irrigated soils as compared to tubewell water irrigated and admixture water irrigated ones. The soil pH was raised by 2 units as a result of wastewater irrigation at site A compared to sites B and C. Wastewater irrigation also result in relatively high concentrations of Ni, Pb and Zn （275.5, 441.3 and 177 mg/kg, respectively） in wastewater irrigated soils over tubewell water irrigated soils. These levels are higher than the maximum permissible limits in unpolluted soils, indicating that a degree of contamination has occurred. This was confirmed by calculated PLIs and contamination factors in soil samples, The results also showed some crops cultivated at sites A and B contained high levels of Ni and Cd beyond the maximum permissible concentrations and those cultivated at site C. The concentrations of these heavy metals are within or very close to the critical levels. HQ indices and daily intake calculated in respect of metal contents in some vegetables （spinach, lettuce and celery） showed that toxic risk due to Cd in these vegetables and crops was greater than one. This study generally concludes that although the content of heavy metals did not reach toxic level, extensive use of untreated wastewater drawn from the Koshk River has obviously increased the contamination of Ni and Pb in soils and Cd in some vegetables cultivated along the canal, causing potential health risk in the long-term scense for consumers or local residents.