Landfill leachate treatment by MBR： Performance and molecular weight distribution of organic contaminant

A membrane bioreactor (MBR) with an air-lift bioreactor and gravity flow is applied to treating landfill leachate. More than 99% of BOD5 (biochemical oxygen demand for five days) removal effi-ciency is achieved with less than 35 mg/L of BOD_5 in the effluent at less than 1.71 kg BOD5/m~3·d of BOD_5 loading rate. When DO (dissolved oxygen) is maintained at the range of 2.3―2.8 mg/L and the loading rate of NH_4~ -N (ammonium nitrogen) is kept at 0.16― 0.24 kg NH_4~ -N/m~3·d, the NH_4~ -N in the effluent is less than 15 mg/L. However, compared with high removal rates of BOD_5 and NH_4~ -N, the removal effi-ciency of soluble chemical oxygen demand (SCOD) varies between 70% and 96%. The investigation of molecular weight (MW) distribution has been carried out by the gel permeation chromatography (GPC) so as to understand the fate of organic matters in the MBR treating of landfill leachate. Results indicate that organic matters of the landfill leachate are composed of a high MW fraction (MW of the peak, MWp = 11480―13182 Da) and a low MW fraction (MWp = 158―275 Da). The high MW fraction is not biode-gradable, but can be decreased with microfiltration membrane. The most of the low MW fraction is bio-degradable, but the residue of the low MW fraction is able to permeate through the membrane, thus re-sulting in high SCOD in the effluent of the MBR.     

现代垃圾填埋场场底防渗衬垫的设计

本文全面介绍了现代垃圾填埋场场底防渗衬垫的种类、设计要求、使用性能和适用范围，并结合工程方案进行了对比、评价，推荐适宜的可行性方案。     

氟系替代工质R407C和R410A与R22在复合冷凝系统中的热力学特性对比研究

目前复合冷凝技术已经形成了行业标准,替代制冷剂在复合冷凝系统中的应用特性研究是一种趋势。有限时间热力学方法和分析方法和SIMULINK软件被引入建立氟系替代制冷剂R407C和R410A在复合冷凝系统的仿真模型,其对象为风冷热泵复合冷凝过程。氟系替代制冷剂R407C和R410A在复合冷凝系统中的热力学特性被模拟,并与原R22系统的性能做了对比。结果表明:R410A复合冷凝系统卫生热水水温上升速度比R22系统快,20 min时上升到约60℃,而R407C复合冷凝系统卫生热水上升速度比R22复合冷凝系统慢,约需50 min水温达到47℃左右。系统效率随用户要求的卫生热水水温温度升高而降低。R410A复合冷凝系统比R22复合冷凝系统略高3%～5%,而R407C复合冷凝系统比R22复合冷凝系统略低。     

煤矿矸石排放对环境的影响

分析了煤矿矸石排放对环境的影响,归纳了目前采用的处理技术,并对国内一些工程实例进行了比较,针对存在的问题,探讨了可能的解决途径。     

并行电法在垃圾渗滤液污染动态监测中的应用

为了查明垃圾渗滤液浸染土壤的污染范围、程度及扩散实时动态情况,利用并行电法系统对室内渗滤液浸染模型开展测试工作。根据垂向和面上两种扩散形式,采用不同布置方式,分别得到三维反演立体电阻率值和电极电流变化曲线图。实验结果显示,三维立体成像和不同时刻电极电流变化趋势两者结合使用,可圈定渗滤液浸润垂向和面上扩散特征,具有时空控制的全面性。此项技术可为实地污染区的探测提供技术支撑。     

城市化对岩溶地下河水质的影Ⅱ向及其环境效应①②-以重庆市南山老龙洞地下河流域为例

目前我国已经进入快速城市化阶段,城市化的同时产生的生活污水及废弃物不断增加,对环境的污染加剧。为了了解人类活动尤其是城市化对岩溶地下河水质的影响,对重庆市南山老龙洞地下河流域上游的污水和老龙洞地下河出口处的河水的温度,pH．电导率、溶解氧和阴阳离子等水化学指标进行了一年的连续性观测。结果表明,老龙洞地下河的主要污染源是上游城镇产生的生活污水,各顷指标都超过了国家地下水质量标准,急需治理。     

垃圾渗滤液中有机物对其厌氧氨氧化的影响

为了考察垃圾渗滤液中有机物对其厌氧氨氧化反应的影响,保证晚期垃圾渗滤液的深度脱氮,采用短程硝化SBR联合厌氧氨氧化SBR(ASBR)两级系统处理氨氮为(2 000±100)mg/L、COD为(2 200±200)mg/L的实际晚期垃圾渗滤液进行试验研究.短程硝化SBR运行了100d,亚硝酸盐积累率达到了95%以上.ASBR采用进水逐步加大渗滤液掺入比例的方式进行驯化.实验结果表明,随着掺入比例的增大,进水可降解COD增加到150 mg/L左右时,ASBR的氮负荷速率从1.20 kg/(m3·d)降到了0.28 kg/(m3·d),氮去除速率从1.10 kg/(m3·d)下降到了0.19 kg/(m3·d),表明系统趋于崩溃.当ASBR进水可降解COD再次降低到50 mg/L左右时,系统的厌氧氨氧化菌活性得到了恢复,最大的氮负荷速率和氮去除速率分别达到了1.55和1.20 kg/(m3·d).定量PCR试验表明,当系统的厌氧氨氧化菌活性得到恢复后,厌氧氨氧化菌占全细菌的比例达到了试验期间的最大值1.94%.     

考虑渗沥液作用的垃圾填埋体组合破坏稳定分析

现代垃圾填埋场基本采用复合衬里结构,破坏面背坡沿垃圾填埋体内部、底坡沿衬里界面的平移滑动破坏形式成为垃圾填埋体可能的组合破坏形式之一。为了在目前该破坏形式稳定性计算方法的基础上考虑渗沥液的影响,假设穿过垃圾填埋体内部的破坏面为主动破坏面,利用刚体极限平衡分析方法,同时分类讨论渗沥液水位相对于特定界面的不同位置关系,得出每种情况下的计算方法。计算分析结果表明：渗沥液水位升高时,垃圾填埋体的破坏由沿衬里界面的平移滑动破坏演变为穿过垃圾填埋体内部和底部衬里的组合破坏;实际工程算例中,发生破坏失稳正是由于渗沥液水位过高引起的。     

生物活性炭去除垃圾渗滤液中难降解有机物

对比SBR和生物活性炭(biological activated carbon,BAC)处理垃圾渗滤液效果,COD去除率分别稳定在10%和25%左右,表明BAC可以去除部分难降解有机物.原位测定SBR和BAC反应器1个运行周期生物降解有机物二氧化碳(CO2)产生量分别为109和306mg,BAC比SBR生物分解有机物量多,表明BAC可以生物分解部分难降解有机物.采用Freundlich方程拟合新活性炭,生物再生活性炭和吸附饱和活性炭的吸附等温线,1/n值分别为2.56,2.94和19.05,表明新活性炭吸附能力最强,生物再生活性炭次之,吸附饱和活性炭最差,生物再生使活性炭的吸附能力得到较好的恢复,证明了生物再生现象的存在.进一步分析认为吸附延长了有机物在反应器内的停留时间,提高了生物分解量.生物再生是BAC去除难降解有机物的本质原因.     

Technique for advanced electrochemical oxidation treatment of nanofiltration concentrate of landfill leachate

Landfill leachate treated with combined process of ＂pretreatment ＋biological treatment ＋advanced treatment （NF）＂ to produce nanofiltration concentrate, which bio-chemical ratio （B/C） is less than 0.1 and CODer concentration is 2 000-2 500 mg/L, high salt content. Which cannot be discharged under existing environ- mental standards. According to analysis based on electrochemical advanced oxidation mechanism, a two-step electrochemical tech- nique was recommended. In the first step, a pulse electrochemical technique was adopted. With Fe as consumption electrode and current density of 10 mA/cm2, the pollutants were removed by means of Fenton reaction, electroflotation and electrocoagulation. In the second step, a double function electrode was used to per- form electrocatalytic oxidation by means of titanium metallic oxi- dates. In the condition that current density being 12.5 mA/cm2, the pollutants were further removed by oxidation and electrolytic deposition. Result shows that the removing rate of CODer, NH3-N and CI were 70%-85%, 90% and 25%, respectively; average value of B/C ratio increased from 0.09 to 0.38 and conductivity reduced by 10%.