Mobilities and leachabilities of heavy metals in sludge with humus soil

Chemical forms of Zn, Ni, Cu, and Pb in municipal sewage sludge were investigated by adding humus soil to sludge and by performing sequential extraction procedures. In the final sludge mixtures, Zn and Ni were mainly found in Fe/Mn oxide-bound (F3) and organic matter/sulfide-bound (F4) forms. For Zn, exchangeable (F1), carbonate-bound (F2), and F3 forms were transformed to F4 and residual forms (F5). For Ni, F1 and F2 forms were transformed to F1, F2, and F3 forms. Both Cu and Pb were strongly associated with the stable forms F4 and F5. For Cu, F2 and F3 forms were major contributors, while for Pb, F3 and F4 forms were major contributors to F5. Humus soil dosage and pH conditions in the sludge were strongly correlated with the forms of heavy metals. Five forms were used to evaluate metal mobilities in the initial and final sludge mixtures. The mobilities of the four heavy metals studied decreased after 28 days. The metal mobilities in the final sludge mixtures were ranked in the following order: Ni > Zn > Cu = Pb. Leaching tests showed that the mobilities of Zn and Ni in lower pH conditions (pH 4) were higher than those in higher pH conditions (pH 8).     

Chemical cleaning of fouled PVC membrane during ultrafiltration of algal-rich water

Cleaning of hollow-fibre polyvinyl chloride (PVC) membrane with di erent chemical reagents after ultrafiltration of algal-rich water was investigated. Among the tested cleaning reagents (NaOH, HCl, EDTA, and NaClO), 100 mg/L NaClO exhibited the best performance (88.4% 1.1%) in removing the irreversible fouling resistance. This might be attributed to the fact that NaClO could eliminate almost all the major foulants such as carbohydrate-like and protein-like materials on the membrane surface, as confirmed by Fourier transform infrared spectroscopy analysis. However, negligible irreversible resistance (1.5% 1.0%) was obtained when the membrane was cleaning by 500 mg/L NaOH for 1.0 hr, although the NaOH solution could also desorb a portion of the major foulants from the fouled PVC membrane. Scanning electronic microscopy and atomic force microscopy analyses demonstrated that 500 mg/L NaOH could change the structure of the residual foulants on the membrane, making them more tightly attached to the membrane surface. This phenomenon might be responsible for the negligible membrane permeability restoration after NaOH cleaning. On the other hand, the microscopic analyses reflected that NaClO could e ectively remove the foulants accumulated on the membrane surface.     

Modeling assessment for ammonium nitrogen recovery from wastewater by chemical precipitation

Chemical precipitation to form magnesium ammonium phosphate (MAP) is an effective technology for recovering ammonium nitrogen (NH4 +-N). In the present research, we investigated the thermodynamic modeling of the PHREEQC program for NH4 +-N recovery to evaluate the effect of reaction factors on MAP precipitation. The case study of NH4 +-N recovery from coking wastewater was conducted to provide a comparison. Response surface methodology (RSM) was applied to assist in understanding the relative significance of reaction factors and the interactive effects of solution conditions. Thermodynamic modeling indicated that the saturation index (SI) of MAP followed a polynomial function of pH. The SI of MAP increased logarithmically with the Mg2+/NH4 + molar ratio (Mg/N) and the initial NH4 +-N concentration (CN), respectively, while it decreased with an increase in Ca2+/NH4 + and CO3 2??/NH4 + molar ratios (Ca/N and CO3 2??/N), respectively. The trends for NH4 +-N removal at different pH and Mg/N levels were similar to the thermodynamic modeling predictions. The RSM analysis indicated that the factors including pH, Mg/N, CN, Ca/N, (Mg/N) (CO3 2??/N), (pH)2, (Mg/N)2, and (CN)2 were significant. Response surface plots were useful for understanding the interaction effects on NH4 +-N recovery.     

国外绿色化工持续升温

鉴于新技术的开发和可持续发展的推动,绿色化学品正不断吸引生产商开发。尽管国际金融危机尚未完全褪去,国外绿色化工却开始持续升温。一些化工巨头已开发了新的可持续发展产品,一些技术和产品被推向了市场,如美国嘉吉(Cargill)公司和日本帝人公司的合资企业NatureWorks公司推出的Ingeo聚乳酸(PLA)聚合物,以及美国的生物科学公司Metabolix与组分、饲料和生物燃料公司ADM(Archer     

化学事故应急处置中环保对策的研究

文章分析化学事故中环境污染问题的形成,阐述了化学事故本身对环境的污染和处置不当造成的环境污染,提出我国消防工作在化学事故处置环保方面存在的不足之处,为消防人员处置化学事故做好环保工作提出建议和对策。     

你的健康是否在受重金属的威胁？

矿产资源滥挖滥采造成的农田重金属污染,目前在我国不少省区已到了触目惊心的地步,因此最近国务院正式批复了由环保部制定的《重金属污染综合防治＂十二五＂规划》,给公众带来了更多的期待。据《规划》起草人之一、环保部环境规划院副院长吴舜泽透露,五大重点防控行业是指重有色金属矿采选业、重有色金属冶炼业、铅蓄电池制造业、皮革及其制品业、化学原料及化学制品制造业。     

数字

61.7%截至2010年12月底,这59条河流化学需氧量和氨氮平均浓度分别为23.7毫克/升和1.4毫克/升,比上年同期分别下降40.4%和61.7%。按常见鱼类能够稳定生存     

地表水中有机污染物的化学需氧量的探讨与研究

有机污染物对地表水的危害主要表现在自身氧化过程对水中溶解氧的消耗,化学需氧量（COD）是评定水中耗氧有机物含量的指标之一,本文主要研究讨论了化学需氧量指标并具体阐述了几种检测方法。