农村生活污水分散式处理研究现状及技术探讨

分散式污水处理研究已经成为一种新的理念,其具有投资少、简单实用、管理方便、效率高、运行成本低等诸多优点,适合于中国农村生活污水处理。污水处理工艺技术的选择直接关系到污水处理效果及当地的环境卫生。本文综述了国内外农村分散式生活污水处理研究现状,对人工湿地、稳定塘、生物滤池、生态浮岛、厌氧生物处理工艺等主要分散式污水处理技术进行了探讨,并对常用的几种分散式污水处理技术进行了分类和比较。本文认为分散式生活污水处理组合工艺具有更强的适用性和应用性,是解决分散式生活污水处理难题的重要途径。     

中国冬油菜氮素养分管理策略

油菜是中国重要的油料作物,长江流域是其最主要种植区域,该区域的气候、土壤和种植制度决定了土壤养分供应特征、油菜生长和养分需求特征。作物高产、经济和养分高效是农业生产及其可持续发展的决定因素,油菜氮素吸收和土壤氮素供应在时间和空间上的不协调造成氮的缺乏或过量是油菜产量和收益的重要限制因子,合理的氮肥施用是保证油菜高产和氮肥高效的关键。论文从作物氮素需求、土壤氮素供应、氮肥施用关键技术及其配套措施等方面综述了国内外油菜氮肥管理的进展。在此基础上,结合中国冬油菜种植区域土壤和作物的特点,提出以"前促后稳"为核心,协调作物氮素需求和土壤氮素供应的冬油菜氮素养分综合管理策略。该策略的核心内容是:通过调节氮肥施用时期、比例和配比,满足油菜前期快速生长的氮素需求,后期则主要通过发挥土壤氮素供应,促进油菜氮素转移再利用;综合考虑不同轮作、秸秆还田条件下土壤氮素供应特点及后效,统筹氮肥的施用;配合合理密植、水肥管理、同其他元素肥料配施、机械深施等措施,以协同增效的方式实现油菜的高产和氮肥的高效。     

水泥固化锌污染红粘土强度与微观孔隙特征

污染场地开挖置换后的污染土经过固化处理（S/S法）,可作为浅层地基或护岸等非敏感区域的建筑材料,进行污染土的二次利用。针对该项技术,将一定量硝酸锌溶液与风干后红粘土混合,掺入适量水泥,并搅拌均匀、压实成型,标准养护7 d和28 d后依次进行无侧限抗压实验、压汞实验和含水率、体积等指标的测定,研究不同锌离子浓度、水泥掺量和养护龄期对锌污染红粘土水泥固化产物强度、微观孔隙和含水率等的影响。实验结果表明：水泥掺量在10%以内,锌离子浓度小于5000 mg·kg-1,固化物强度随龄期增长而增加;锌离子浓度大于5000 mg·kg-1,强度随龄期增长而先增加后减小。水泥掺量6%和8%时,固化物强度与锌离子浓度呈负相关;而水泥掺量10%时,锌离子浓度对强度的影响存在阈值,且阈值在1000 mg·kg-1附近。与不含锌离子的28 d固化物相比,锌离子浓度小于1000 mg·kg-1时,固化产物孔径小于10 nm的孔隙增加,孔径大于10μm的孔隙减少,强度提高;锌离子浓度在大于1000 mg·kg-1时,严重阻碍C-S-H凝胶物的生成,10μm以上的孔隙和总孔隙率均显著增加,并且生成大量孔径为0.1~10μm的无定型物,同时使红粘土出现亲水性,养护过程中吸收水分且体积增加,强度则大幅度降低。     

石化废水稳定塘系统下渗对地下水的影响

稳定塘是一种古老而又不断发展的污水生物处理系统,目前在污水资源化方面有着广泛的应用,但是如果稳定塘系统防渗处理不当,会导致地下水污染.在中石化两北某市石化公司稳定塘中试工程一年多运行过程中,研究了3种稳定塘工程不同防渗层的防渗效果,连续对取样井中下渗后污水的水质变化情况进行监测,进而判断稳定塘系统对地下水的影响.结果表明,防渗效果优劣顺序是:红粘土机械压实>灰混土压实.污水下渗后水中TDS明显增大,平均浓度由1.2 g·L-1增大到4.3 g·L-1;包气带对COD、氨氮、石油烃、挥发酚、硫化物均有一定的净化效果,各污染物浓度分别减少了7.8%、24.1%、19.9%、35.3%、37.5%;氰化物浓度几乎不变.由于污水是经过二级生化处理的石化废水出水,其中的有机物大部分是难生物降解的有机物,进入含水层中将更难以去除,所以下渗对地下水污染风险最大的是污水中的有机物.此外,下渗使地下水水位上升从而造成土壤次生盐渍化.     

Modification and Application of Fly Ashfor the Stabilization of Sludge

Under the microwave irradiation, a highly effective adsorptive material zeolitized fly ash (FZ) was made by adding a certain amount of mineralizer in the raw material of the limestone and fly ash. The structure of zeolite and the mechanism of modification were investigated by the analysis of XRD and SEM.The stabilization mechanism was analyzed and the variation of heavy metals and nutrient contents in sewage sludge were investigated through the sludge stabilization experiment by mixing zeolitized fly ash in the municipal sewage sludge. It was indicated that the zeolitized fly ash had obvious stabilization effect to heavy metals (Zn、Cu、Mn) and had apparent retention ability to the nutrients contents of N、P of the municipal sewage sludge. The heavy metals contents of Zn, Cu and Mn were all significant lower than those in the national control standards for pollutants in sludges from Agricultural. After the stabilization treatment of the municipal sewage sludge, the total content of N was lower than that in the national surface water environmental quality standards (10 mg/L), the total content of P was lower than that in Quality Standard of the Sewage discharged into the city sewer system(1 mg/L).     

土壤固化酶在中国的应用及研究进展

土壤固化酶于二十世纪八十年代逐渐应用于筑路、筑堤、筑坝、垃圾填埋处理、基础加固等领域,中国自1995年将土壤固化酶应用于道路建设以来,取得了一些经验和成效,但也存在一些问题。该文概述了土壤固化酶在中国的应用及研究进展;分析了其所具有的环保价值、可产生经济效益,以及土壤固化酶在中国推广应用过程中出现的一些问题;通过土壤固化酶与石灰、水泥等传统固化材料对土的无侧限抗压强度影响的试验研究,说明土壤固化酶有利于土体稳定的特性;为进一步研究和发展该技术提供依据     

Soil bacterial community responses to cadmium and lead stabilization during ecological restoration of an abandoned mine

Ecological restoration refers to the gradual recovery of damaged ecosystems by utilizing their self-recovery capacity and artificial measures. It is considered as an effective technique to alleviate heavy metal pollution in open-pit mining soils. However, little is known about the stability of heavy metals and soil bacterial responses in artificially restored soil-plant systems. In this study, different vegetation restoration strategies were established in the Dabaoshan mining area, China, and the accumulation and transfer of Cd/Pb in the soil-plant system and the responses of the soil bacterial community were investigated. Results showed that ecological restoration with a combination of trees, shrubs and grasses/herbs could increase soil cation-exchange capacity and organic matter content, but not soil pH. The mixture of trees, shrubs and grasses/herbs was most effective for reducing the available Pb content to 33.7% of the content in the control, and the mixture of trees and grasses/herbs was beneficial in reducing Cd to 60.4% of the content in the control. Data showed that ecological restoration could change the quantity, composition and community structure of soil microorganisms. The soils in which a mixture of trees, shrubs and grasses/herbs were grown had the greatest abundance and diversity of bacteria; the abundances of Proteobacteria increased by 12% and Actinobacteria by 5% from those of the control. Plant coverage, soil available Cd content, and organic matter emerged as major determinants of bacterial community composition. This study demonstrates a promising remediation strategy for limiting Cd/Pb mobility in mining areas.     

基于模型法对猪舍最佳清理时间的确定

规模养殖的牲畜排泄物堆积将影响牲畜本身的健康、引起环境污染和清理人员身体健康问题,因此确定最佳清理时间的评估方案显得尤为重要。文章基于模型法对排泄行为进行定态化假设,引入排泄物状态预测模型,对人工清理和水冲机器清理的两种主流清理方式确定最佳清理时间,最终采用种群模型优化定态化假设分析改进。     

土壤重金属固化稳定化材料研发及其应用基础研究进展

固化稳定化是土壤重金属污染治理的主要技术之一，加强对固化稳定化材料的环境功能研发尤为重要。土壤重金属固化稳定化材料作用机理包括沉淀作用、吸附作用、配位作用、有机络合作用和氧化还原作用等。本文重点围绕土壤重金属固化稳定化材料研究的系统化，提出土壤重金属固化稳定化材料的研发方法，如材料筛选对比方法、优化复配方法、表面改性方法、表面负载和桥连复合等，固化稳定化材料应用基础研究框架包括固化稳定化材料-重金属-水体、固化稳定化材料-土壤-重金属、固化稳定化材料-土壤-植物-重金属、固化稳定化材料-田间-作物-重金属，以及重金属治理的环境安全和应用效果评价等5个层次，针对每个层次研究主要内容及其关键环节进行要点说明，旨在为促进土壤重金属固化稳定化材料的规范化和系统化研究、强化土壤重金属固化稳定化的应用基础研究提供科学参考。     

Application of biocementation technique using Bacillus sphaericus for stabilization of soil surface and dust storm control

Dust emission and wind erosion are widespread phenomena in arid and semi-arid regions, which have far-reaching harmful effects to the environment. This study aimed to use microbial induced carbonate precipitation (MICP) method with Bacillus sphaericus to reduce soil losses that occur in a dust-producing area due to wind erosion in the Ilam Province, Iran. Soil samples at the 0-30 cm depth were used and sterilized in an autoclave for 2 h at 121°C and 103 kPa. Approximately 3 kg soils were weighed and poured in the 35 cm×35 cm×3 cm trays. Different treatments included two levels of B. sphaericus (0.0 and 0.5 OD), three levels of suspension volume (123, 264, and 369 mL), two levels of urea-chloride cementation solution (0.0 and 0.5 M), and two levels of bacterial spray (once and twice spray). After 28 d, soil properties such as soil mass loss, penetration resistance, and aggregate stability were measured. The results showed a low soil mass loss (1 g) in F₁₄ formulation (twice bacterial spray+264 mL suspension volume+without cementation solution) and a high soil mass loss (246 g) in F₅ formulation (without bacteria+264 mL suspension volume+0.5 M cementation solution). The highest (42.55%) and the lowest (19.47%) aggregate stabilities were observed in F₁₆ and F₇ formulations, respectively, and the highest penetration resistance (3.328 kg/cm²) was observed in F₁₈ formulation. According to the final results, we recommended the formulation with twice bacterial spray, 0.5 M cementation solution, and 269 mL suspension volume as the best combination for soil surface stabilization. Furthermore, this method is environmentally friendly because it has no adverse effects on soil, water, and plants, thus, it would be an efficient approach to stabilize soil surface.