皮革废水混凝处理实验研究

采用混凝剂对皮革废水进行混凝处理。对3种无机混凝剂和一种有机混凝剂进行了筛选,研究了pH值和投药量对废水中SS、COD、铬和色度等污染物去除效果的影响。结果表明,当pH值在酸性和中性时,效果不明显;当pH值为碱性时,效果显著。硫酸亚铁、硫酸亚铁+PAM和聚合氯化铝(PAC)+PAM 3种混凝剂组合具有良好的混凝效果,在合适的pH值和投药量下,SS和COD的去除率分别达到80%和30%以上,铬和色度的去除率分别达到95%和50%以上。且硫酸亚铁混凝效果好,成本低,适合小型皮革企业需求。     

微波辅助工艺处理天然气净化废水的应用研究

进行了微波辅助工艺处理天然气净化废水的应用研究,考察了废水色度、COD、SS、含油量和细菌的去除效果以及对废水腐蚀率的降低作用,并进行了同等条件下的常温对照实验。研究结果表明:微波絮凝工艺中絮凝剂PAC和PAM的用量较常温下减少了100 mg/L和5 mg/L,絮凝沉降时间仅为常温絮凝的1/4,最佳微波辐照时间下废水的COD去除率比常温条件下提高4.6%。微波工艺处理后,难降解天然气净化废水的含油量去除率达到了94%、废水中硫酸盐还原菌死亡率达97%以上,废水腐蚀率降为原来的1/7,废水可生化性得到了很大提高,可直接进行好氧生化处理。实验表明,微波辅助工艺对难降解天然气净化废水具有很好的处理应用效果。     

人口红利、结构红利与区域经济增长

现有的研究中忽视了人口红利与结构红利具有的内在联系,结果主观的拆分了劳动力投入增加和劳动力部门间转移对经济的增长效应,并在研究过程中对二者的增长路径和传导机制模糊化处理,也就出现了研究结论大相径庭的情况。本文通过在模型中同时引入人口红利和结构红利增长效应的代理变量,对我国四大经济板块进行误差修正分析。研究结果显示人口红利的产出效应在西部和中部地区对经济增长产生抑制作用,而资本积累效应在各个地区均不显著;结构转型过程中的劳动力(行业,空间)流动带来的增长效应在中部和东北地区效果较明显,其他地区甚至是负作用。资本要素(行业,空间)转移作用不明显,在中部和西部地区甚至出现抑制作用。土地要素的形态(用途)转移对东部沿海地区经济增长产生了负向作用,而在中部、西部和东北地区却呈现巨大的促进作用。     

Removal of low concentrations of ammonium and humic acid from simulated groundwater by Vermiculite/Palygorskite mixture

Contaminants in water are classified into different types based on their physical and chemical properties. Thus, more than one type of sorbents may be needed for their removal. In this article, a combination of vermiculite with palygorskite was studied for their simultaneous removal of ammonium and humic acid from simulated groundwater. Batch results showed that the Langmuir model described ammonium adsorption well with an adsorption capacity of 22 mg/g while the humic acid adsorption data fitted to the linear adsorption better, suggesting different removal mechanisms of these two types of contaminants. Kinetic studies showed an instantaneous removal of ammonium and humic acid. A column packed with mixture of equal volumes of vermiculite and palygorskite could treat 100 pore volumes for ammonium removal at an initial concentration of 10 mg/L and 500 pore volumes for humic acid removal at an initial concentration of 20 mg/L before the effluent concentrations exceeded the standard.     

有机改性剂对水中有机氯农药提取效率的影响研究

通过有机改性剂在液液萃取和固相萃取条件下水中有机氯农药的提取效率比对分析,首次探讨了有机改性剂对水中有机氯农药提取效率的影响。结果表明,(1)液液萃取前处理水样中不加有机改性剂、固相萃取前处理水样中添加一定量有机改性剂时,水中有机氯农药的提取效率较高;(2)采用正交实验优化水中有机氯农药固相萃取的提取效率实验表明,有机改性剂添加量对其影响大于有机改性剂种类对其影响;最佳优化方案为水样中添加1%甲醇时,提取效率最高。     

四川望佳人工湿地系统生活污水净化效果

取样监测分析了望佳人工湿地系统各组成单元对COD、TN、NH3-N、TP和SS的去除效果。在水力负荷为0.18 m3/m·d、温度为8~19℃、p H为6~8的条件下,分析结果表明,各单元COD、TN、NH3-N、TP和SS的系统去除率满足:人工快渗池>厌氧调节池>1号表流湿地>潜流湿地>氧化塘>2号表流湿地>1号水平潜流湿地>2号水平潜流湿地,其中人工快渗池单元的系统去除率平均值分别为21.21%、22.74%、22.49%、25.58%和30.85%。监测期间COD、TN、NH3-N、TP和SS的总去除率平均值分别为89.41%、90.27%、89.89%、89.89%和92.28%,系统出水达《城镇污水处理厂污染物排放标准》GB18918-2002一级标准的B标准。监测表明,该湿地设计偏于保守,还可以优化设计单元以减少建设和运行成本。     

Effects of drought stress on leaf gas exchange and chlorophyll fluorescence of Glycyrrhiza uralensis

Leaf gas exchange and chlorophyll fluorescence of Glycyrrhiza uralensis Fisch at two water supplies (equivalent to 240 mm for present precipitation and to 120 mm for future decreasing precipitation) were compared. There was a midday depression in net photosynthetic rate (P _N) for either treatment, but stomatal limitation was dominant for present precipitation treatment and non-stomatal limitation for the drought treatment. Compared with present precipitation treatment, P _N, stomatal conductance (g _s) and transpiration rate (E) were always lower at drought stress, but stomatal limitation value (L _s) and water use efficiency (WUE) were higher in the morning. The decrease in carboxylation efficiency (CE), apparent quantum yield (AQY), light-saturated photosynthetic rate and maximal photochemical efficiency of photosystem 2 (PS 2) (F _v/F _m) suggested that rubisco activity reduced and PS 2 partially inactivated during the day under drought. However, part of this inactivation of PS 2 might be alleviated due to increased thermal dissipation under drought.     

Effect of initial pH control on biological phosphorus removal induced by the aerobic/extended-idle regime

Recently, it has been reported that biological phosphorus removal (BPR) can be induced by an aerobic/extended-idle (AEI) regime. This study further investigated the effect of initial pH ranging from 6.6 to 8.2 on BPR in the AEI process, and compared the BPR performance between the AEI and the anaerobic/oxic (A/O) regimes under their optimal initial pH value. Experimental results firstly showed that phosphorus removal linearly increased with initial pH increasing from 6.6 to 7.8, but slightly decreased when initial pH increased from 7.8 to 8.2. The optimal initial pH should be controlled at 7.8, and the phosphorus removal at initial pH 7.8 was approximately 1.7-time than that at initial pH 6.6. The mechanism studies showed that the biomass cultured at initial pH 7.8 contained more polyphosphate accumulating organisms (PAOs), lower glycogen accumulating organisms (GAOs), and had higher activities of exopolyphosphatase and polyphosphate kinase than that cultured at initial pH 6.6. Cyclic studies revealed that initial pH control affected the transformations of intracellular polyhydroxyalkanoates and glycogen, which might thereby influence microbial competition between PAOs and GAOs. Then, BPR performance between the AEI and the A/O regimes by adjusting initial pH at 7.8 was also compared. The results showed the AEI regime could drive a better BPR than the generally accepted A/O regime (98% vs 88%). Finally, controlling initial pH at 7.8 to promote BPR in the AEI process was confirmed for a municipal wastewater.     

Immobilization of Cd in landfill-leachate-contaminated soil with cow manure compost as soil conditioners: A laboratory study

Introducing cow manure compost as an amendment in landfill-leachate-contaminated soils is proved to be an effective technique for the immobilization of Cd in this study. Landfill-leachate-contaminated soil was collected from an unlined landfill in China and amended with a different blending quantity of cow manure compost (0, 12, 24, 36, and 48 g per 200 g soil), which was made by mixing cow manure and chaff at a ratio of 1/1 and maturing for 6 months. pH values of five different blending quantity mixtures increased by 0.2–0.4, and the organic matter levels increased by 2.5–7%, during a remediation period of 5 weeks. Four fractions of Cd named exchangeable Cd, reducible Cd, oxidizable Cd, and residual Cd in soil were respectively analyzed by a sequential extraction procedure. Introducing the cow manure compost application resulted in more than 40% lower exchangeable Cd but a higher concentration of oxidizable Cd in soils, and mass balance results showed nearly no Cd absorption by applied material, indicating that transformation of exchangeable Cd into oxidization forms was the main mechanism of Cd immobilization when cow manure compost was used as an amendment. The Pearson correlation showed that increasing of pH values significantly improved the efficiency of Cd immobilization, with a correlation coefficiency of 0.940 (p < 0.05). This is the first attempt at heavy metal immobilization in landfill-leachate-contaminated soil by cow manure compost, and findings of this work can be integrated to guide the application.

Implications: Addition of cow manure compost (CMC) was effective in reducing exchangeable Cd in landfill-leachate-contaminated soils (LLCS). The immobilization effect of Cd was mainly assigned to the redistribution of labile soil Cd. Organic matter (OM) and pH value increased with CMC application. The pH values were more sensitive to Cd immobilization efficiency. It was proved that CMC can be safely and effectively used for the restoration of LLCS.