风量对高频气力分选机分选效率及金属分布规律的影响——以废弃印刷电路板粉末为例

以金属高富集粒级0.5～0.125 mm的废弃电路板为分选物料,通过ICP-AES测定分选产品,研究了风量对高频气力分选机分选效率及金属分布规律的影响.结果表明,风量变化对分选效率及金属分布规律影响显著,当风量为200m3/h时分选效率达到最大值78.23％,铜品位为86.745％,相比原料中铜品位13.96％,富集约6.2倍.随着风量的变化,金属的分布呈现规律性变化:密度比铜大或与铜相差不多的金属颗粒(铅、铂和锌等),其变化规律与铜相似,回收率在85％左右变化;密度比铜小很多的金属颗粒(铝、镁等),由于其密度与分选物料中的非金属非常接近,在分选过程中会随非金属带人轻产物中去,从而造成重产物中铝和镁品位最低,甚至低于其在原料中的品位.所以若要分离富集铝和镁,须对分选后的物料进行二次分选.     

一株耐铬不动杆菌对十二烷基硫酸钠的降解特性

研究醋酸钙不动杆菌H1的降解广谱性时,发现其能在高浓度十二烷基硫酸钠(SDS)环境中生长。经过对菌株H1降解特性研究,结果表明,该菌利用SDS的最适温度为30℃,最适pH为7.0,最适接种量为2%,并适应低渗透压环境。当SDS浓度低于400 mg/L时,菌株H1对SDS的降解率在85%以上,且在SDS浓度为400 mg/L时,达到最大降解率94%。当K2Cr2O7为500 mg/L时,菌株H1对SDS的降解率仍达到50%左右。添加酵母浸出物可促进SDS的降解。     

温度对SBR单级好氧生物除磷性能的影响

以合成废水为研究对象,以丙酸钠作为单一碳源,分别设置温度为5、15、25、35℃的4组序批式反应器(R1、R2、R3、R4),考察了温度对单级好氧工艺除磷的影响。结果表明,稳定运行阶段,R1、R2、R3、R4出水磷浓度分别为4.05、2.17、1.34和0.11 mg/L,去除效率分别为61.5%、79.3%、87.2%和99.0%,吸磷速率分别为0.501、1.432、2.538和3.700mg P/(g VSS·h),即提高温度有利于磷的去除。此外,各反应器中多聚磷酸盐激酶(PPK)和外切磷酸盐酶(PPX)活性分别为0.093、0.213、0.376、0.549 U和0.010、0.019、0.029、0.025 U,导致吸磷速率和释磷速率随之增大,可知温度影响聚磷菌PPK和PPX的活性,从而影响除磷效果。静置阶段,聚磷菌体内储能物质糖原质和聚羟基脂肪酸酯基本保持不变,但各反应器均出现了释磷现象,聚磷作为主要供能物质,单位释磷量分别为1.95、6.42、9.90和9.56 mg P/(g TSS),提高温度可促进静置段聚磷分解提供能量,从而驱动好氧吸磷达到更好的除磷效果。     

Speciation of Cu and Zn during composting of pig manure amended with rock phosphate

Pig manure usually contains a large amount of metals, especially Cu and Zn, which may limit its land application. Rock phosphate has been shown to be effective for immobilizing toxic metals in toxic metals contaminated soils. The aim of this study work was to investigate the effect of rock phosphate on the speciation of Cu and Zn during co-composting of pig manure with rice straw. The results showed that composting process and rock phosphate addition significantly affected the changes of metal species. During co-composting, the exchangeable and reducible fractions of Cu were transformed to organic and residue fractions, thus the bioavailable Cu fractions were decreased. The rock phosphate addition enhanced the metal transformation depending on the level of rock phosphate amendment. Zinc was found in the exchangeable and reducible fractions in the compost. The bioavailable Zn fraction changed a little during the composting process. The composting process converted the exchangeable Zn fraction into reducible fraction. Addition of an appropriate amount (5.0%) of rock phosphate could advance the conversion. Rock phosphate could reduce metal availability through adsorption and complexation of the metal ions on inorganic components. The increase in pH and organic matter degradation could be responsible for the reduction in exchangeable and bioavailable Cu fractions and exchangeable Zn fraction in rock phosphate amended compost.     

改进气相色谱法测定总烃与非甲烷总烃

采用十通阀、双定量环进样(进样量0.5 m L),专用的甲烷柱和总烃柱分别分离两路气样,单FID检测器检测的方法测定环境空气和固定污染源废气中的总烃和非甲烷总烃(NMHC)。实验结果表明:总烃与甲烷工作曲线的相关系数分别为0.997 7和0.999 0;总烃与甲烷测定结果的相对标准偏差均未超过1.5%;总烃与NMHC的检出限均为0.04 mg/m~3;总烃的加标回收率为90.3%~113.0%,NMHC的加标回收率为91.1%~110.0%。上述指标均满足HJ 604—2011和HJ/T 38—1999中对总烃及NMHC的测定要求。用注射器采样后的气样应尽量避光保存,放置时间宜在8 h之内。该方法无需制备除烃空气,大幅提升了检测效率。     

广东和海南红树林的生物地球化学特征

本文研究了广东和海南红树林的土壤,植物叶子和死地被物的化学成分以及它们之间的相互关系,并与相同地区的一些植物群落进行比较,从而探讨红树林的生物地球化学特征。结果表明,红树林的土壤和植物的某些化学成分含量较高,尤其是Na和Ca的含量较为突出。另外,虽然海岸带海水的pH＞8,土壤都呈酸性。红树林的养分利用率只有N较高,其余大多数元素都较低。红树林的生物吸收率和生物归还率通常也较低,但其大多数元素的生物分解率则较高。     

Pollution characteristics and health risk assessment of benzene homologues in ambient air in the northeastern urban area of Beijing, China

Ambient benzene homologues were measured at a site in the northeastern urban area of Beijing, China, from August 24 to September 4, 2012 by SUMMA canister sampling followed by laboratory determination using cryogenic cold trap pre-concentration-GC-MS/FID, and their health risks were also assessed. Daily total benzene homologues ranged from 0.99 to 49.71 μg/m3with an average of 11.98 μg/m3. Benzene homologues showed higher concentrations in the morning and evening than that at noontime. Comparison with previous studies revealed a trend of decrease for ambient benzene homologues probably due to the efective emission control in Beijing in recent years. Vehicular exhaust was the main source while volatilization of paints and solvents also made substantial contributions. Health risk assessment showed that BTEX(benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) and styrene had no appreciable adverse non-cancer health risks for the exposed population, while benzene has potential cancer risk of 1.34E-05. Available data from cities in China all implied that benzene imposes relatively higher cancer risk on the exposed populations and therefore strict control measures should be taken to further lower ambient benzene levels in China.     

西南环境移民安置地的生态环境状况

以桂西北环江县肯福环境移民安置示范区为例，对我国西南喀斯特地区，环境移民安置区的气候、地貌、土壤与植被等主要生态因子，进行了调查研究与取样分析，研究表明，环境移民安置地由于地处亚热带季风气候区，具有气候温暖，雨量充沛、日照充足，且雨热同季的特点；地貌破碎，土地以坡地为主，但有一定量可开垦利用的土地；土壤主要为红壤，土壤剖面发育良好，有机质和氮含量相对丰富，磷、钾缺乏，土壤酸度大，土壤质地和结构尚可