Bioelectrochemical acidolysis of magnesia to induce struvite crystallization for recovering phosphorus from aqueous solution

A novel struvite crystallization method induced by bioelectrochemical acidolysis of magnesia(MgO) was investigated to recover phosphorus(P) from aqueous solution using a dual-chamber microbial electrolysis cell(DMEC). Magnesium ion(Mg~(2+)) in the anolyte was firstly confirmed to automatically migrate from the anode chamber to the cathode chamber, and then react with ammonium(NH+4) and phosphate(PO_4~(3-)) in the catholyte to form struvite. Recovery efficiency of 17.8%–60.2% was obtained with the various N/P ratios in the catholyte. When MgO(low solubility under alkali conditions) was added into the anolyte, the bioelectrochemical acidolysis of MgO naturally took place and the released Mg~(2+)induced struvite crystallization in the cathode chamber for P recovery likewise.Besides, there was a strong linear positive correlation between the recovery efficiency and the MgO dosage(R~2= 0.935), applied voltage(R~2= 0.969) and N/P ratio(R~2= 0.905). Increasing the applied voltage was found to enhance the P recovery via promoting the MgO acidolysis and the released Mg~(2+)migration, while increasing the N/P ratio in the catholyte enhanced the P recovery via promoting the struvite crystallization. Moreover, the electrochemical performance of the system was promoted due to more stable anolyte pH and lower pH gradient between the two chambers. Current density was promoted by 10%, while the COD removal efficiency was improved from 78.2% to 91.8% in the anode chamber.     

PAHs in surface sediments from coastal and estuarine areas of the northern Bohai and Yellow Seas, China

Polycyclic aromatic hydrocarbon (PAH) concentrations and their risks in surface sediments (n = 35) collected from coastal and estuarine areas of the northern Bohai and Yellow Seas, China, were investigated in 2008. Total concentrations of PAHs ranged from 52.3 to 1,870.6 ng/g dry weight. The greatest concentrations were observed in the Dou River of Tangshan where waste water from small factories is discharged into the river without treatment. At other locations, municipal sewage was the primary contributor of PAHs. Regional differences in concentrations of PAHs in sediments are related to human activities. Concentrations of PAHs were significantly correlated with concentrations of organic carbon in sediments. The patterns of relative concentrations and types of PAHs observed and knowledge of the potential sources, as well as the results of a principal component analysis, are consistent with the primary sources of PAHs in sediments of the northern Bohai Sea and Yellow Sea, being derived from the high-temperature pyrolytic processes such as combustion of fossil fuel. While concentrations of PAHs at most locations did not exceed the effects range median stated by the numerical effect-based sediment quality guidelines of the United States, concentrations of PAHs at some locations were similar to or greater than the effects range low.     

固化污泥中Cu、Zn形态的转化及对浸出毒性的影响

污泥经过固化处理后,能稳定其中的重金属,降低其浸出毒性,减少对环境的二次污染。但固化污泥中重金属的潜在毒性与其形态有着紧密的联系,仅仅通过浸出毒性指标不能全面反映固化污泥中重金属的潜在污染。通过Tessier五步浸提法分析污泥固化前后、不同固化材料掺入量对重金属形态的影响,并对其形态与浸出毒性进行对比分析。研究结果表明,污泥固化后Cu、Zn的有机结合态变化最大,一般情况下Cu、Zn的浸出毒性指标均不能全面反映其潜在毒性。     

电脱盐废水处理技术现状

近几年,随着原料油的劣质化、重质化、乳化严重,造成电脱盐装置在运行过程中乳化困难,从而导致原油电脱盐脱水合格率低。文章介绍了石油炼制企业电脱盐废水的概况和水质特点,针对原油性质恶化、原油预沉降处理时间不够和石油炼制工艺差异三个因素,分析了其对电脱盐废水的盐含量、金属离子含量、酸值、胶质沥青质含量、乳化程度等水质水量特征的影响。介绍了目前电脱盐废水处理技术的进展,结合几个典型炼化企业电脱盐废水处理工艺应用现状,展望了电脱盐废水处理技术的发展趋势。     

磷酸二氢钾-磷酸氢二钠缓冲溶液调控下白菜对钼矿区重金属污染土壤的修复

取同质钼矿区土壤放于通风处自然风干,平行A、B两组盆栽实验。A组直接投放不同浓度的磷酸二氢钾-磷酸氢二钠缓冲溶液50 ml,B组做对照,种植白菜,待白菜生长50 d后再投加一次缓冲溶液50 ml,60 d后收割其地上部分及对应土壤进行消解。采用ICP-AES分析土壤及植物体中各种重金属元素的含量,研究了在磷酸二氢钾-磷酸氢二钠缓冲溶液在其不同浓度梯度下投加,白菜地上部分对钼矿区重金属污染土壤的修复潜力。结果表明：在投加磷酸二氢钾-磷酸氢二钠缓冲溶液的条件下均能显著提高白菜的地上部分富集土壤中重金属元素的能力（Cd除外）,但缓冲溶液对白菜积累重金属能力的促进作用也存在重金属元素种类及浓度梯度之间的差异;投加pH=7.3磷酸二氢钾-磷酸氢二钠缓冲溶液可以较好地去除钼矿区污染土壤中的Cr、Mo、Ni、Pb;投加pH=7.7磷酸二氢钾-磷酸氢二钠缓冲溶液可以较好地去除钼矿区污染土壤中的As、Cu、Hg、Zn。     

河口有机物在固-液界面迁移转化研究进展

河口复杂的水动力条件和丰富的泥沙含量,使得河口水体中固-液界面过程成为控制河口有机物迁移转化的关键环节.本文总结了有机物固-液界面吸附机理以及河口区有机物在悬浮物-水界面、沉积物-水界面的迁移转化,并对今后研究工作提出几点看法.     

福建东山湾养殖贝类重金属污染状况及健康风险评价

为了解东山湾海水养殖贝类重金属污染状况及健康风险水平,2016年11月采集了华贵栉孔扇贝(Chlamys nobills)、菲律宾蛤仔(Ruditapes philippinarum)、鲍(Haliotis sp.)、巴非蛤(Paphia sp.)、牡蛎(Saccostrea sp.)和翡翠贻贝(Perna viridis)等6种常见贝类,对其污染指数、膳食暴露量和健康风险等进行评价。结果表明,东山湾贝类体内Cu、Zn、Pb、Cd、Cr、As和Hg含量(均值)分别为9.69、0.19、43.5、0.65、0.21、0.010和1.69μg·g~(-1),与第一类海洋生物质量标准限值相比,Cu、Pb、Zn、Cd、Cr和As的超标率分别为16.7%、83.3%、33.3%、33.3%、16.7%和100%;但除华贵栉孔扇贝Cd含量超标外,Pb、Cr、Hg和As含量均能满足食品中污染物限量标准要求。尽管东山湾贝类总致癌风险R_c=1.65×10~(-4),存在一定的健康风险,但5种贝类体内重金属含量略低于我国东部-南部沿海贝类的平均水平,且2010—2017年期间东山湾牡蛎体内重金属污染状况没有明显变化(养殖生物质量指数<5%),加上重金属膳食暴露风险较低,总非致癌风险R_n=0.94(<1),总体而言贝类质量状况尚可。     

细颗粒物的免疫毒性研究进展

近年来,我国机动车数目迅猛增加及以煤炭为主的能源消耗大幅攀升,区域灰霾现象频发,细颗粒物的环境空气污染问题日益凸显.细颗粒物由于其成分、粒径与来源等的多样性,对健康的影响更为严重和复杂.细颗粒物可通过破坏组织屏障、损伤免疫细胞、调节细胞因子的分泌等方式影响免疫系统的功能,与多种慢性炎症性疾病的发生发展密切相关,但其致病机制尚未阐明.本文对细颗粒物致人体的免疫毒性效应及其可能机制进行综述,并提出今后开展此类研究的建议.     

好氧颗粒污泥和活性污泥细菌种群结构对五氯酚污染的响应研究

应用一种新的微生物分子生态学方法--末端限制性片段长度多态性(T-RFLP)法研究了好氧颗粒污泥和活性污泥在毒性化合物五氯酚(PCP)影响下的废水处理性能及其微生物种群结构的响应.结果表明,PCP浓度为30 mg·L-1时,颗粒污泥和活性污泥的COD去除率为38%、77%,与10～20 mg·L-1 PCP相比,分别下降了56%和15%.另外,PCP浓度为20 mg·L-1时,去除率为13%和58%,与10～20 mg·L-1 PCP相比,分别下降了86%和40%,说明PCP对氨氮去除率的影响大于对COD去除率的影响,对颗粒污泥的影响大于对活性污泥的影响.PCP对好氧颗粒污泥和活性污泥的细菌种群结构都产生了明显的影响,而且好氧颗粒污泥的变化程度大于活性污泥;PCP浓度为30 mg·L-1时,好氧颗粒污泥中的细菌种群数量明显下降,TRFs片段数从26下降到14,但活性污泥中的细菌种群数量基本不变,污泥中细菌种群结构的变化趋势与污泥的水处理性能的变化趋势相一致.     

杭州市区蔬菜基地蔬菜重金属含量研究

通过对杭州市区主要蔬菜基地蔬菜中8种重金属含量监测分析与评价，结果表明，江干区蔬菜基地除茄果类蔬菜外，其他种类蔬菜中部分重金属指标均存在超标现象。下沙经济开发区蔬菜基地蔬菜中重金属含量均未超标。