Impacts of sodium hydroxide and sodium hypochlorite aging on polyvinylidene fluoride membranes fabricated with different methods

This study compared the effects of chemical aging on the polyvinylidene fluoride(PVDF)membranes fabricated with the methods of non-solvent induced phase separation(NIPS)(named NIPS-PVDF) and thermally induced phase separation(TIPS)(named TIPS-PVDF). The chemical solutions of sodium hypochlorite(NaClO) and sodium hydroxide(NaOH) were chosen at the concentration of 5000 mg/L. The equivalence of 5 and 10 years was respectively selected as the time of aging. The physicochemical evolutions of membrane aging are characterized on the base of morphology analysis, chemical components, permeation ability and mechanical properties. The aging of NIPS-PVDF membrane led to the elimination of surface hydrophilic additives, while NaO H focused on the dehydrofluorination process resulting in the formation of conjugated chains of polyene on the skeleton structure. The chemical components of the surface of TIPS-PVDF membrane were removed continuously during the aging processes of both NaClO and NaOH, which was caused by the saponification of surface additives and the chain scissions of skeleton structure, but without producing any obvious conjugated chains of polyene. All the aging processes led to the increase of contact angle and the decrease of mechanical properties, and the permeability was reduced first and increased later due to the enlargement of surface membrane pores and membrane block. With the influence of membrane aging, selectivity of membrane was decreased(except coliform bacteria). At the beginning of filtration, the turbidity and particle count were at relatively high levels and declined with the filtration process.     

Effects of humic acid on recoverability and fractal structure of alum-kaolin flocs

Particle surface characteristics, floc recoverability and fractal structure of alum-kaolin flocs were investigated using in situ particle image velocimetry (PIV) and microbalance with or without humic acid. Experimental results indicated that the zeta potential of kaolin particle surface after adsorption of humic acid was related with humic acid concentration and its acid-base bu ering capacity. Adsorption of humic acid resulted in more negative electrophoresis on the particle surface. Coagulant dosages for particles to form flocs would increase with increasing humic concentration. PIV was used to evaluate floc structural fragmentation, floc surface erosion as well as recoverability after high shear. It was found that the floc size during the steady phase of growth was small, while the regrowing capability decreased in the presence of humic acid. The recoverability was closely related with floc breakage modes including floc structural fragmentation and floc surface erosion. The fractal dimensions of alum-kaolin flocs by mass-size method based on microbalance would decrease with increasing humic concentration. This study proved that humic acid had adverse influences on the performance of coagulation process.     

氯代有机溶剂共降解研究进展

本文综述了有机氯溶剂的微生物共降解过程。多种多样的微生物能够通过共代谢途径降解有机氯溶剂。共降解是由微生物细胞内的关键酶进行的。影响共降解的主要因素包括关键酶的诱导 ,毒性抑制和自我恢复以及能量供应等。本文对共降解过程的机理和相关的数学模型进行了综合分析。在此基础上 ,提出了一个能够揭示共降解过程各种因素之间内在逻辑关系的结构模型 ,对于从细胞和酶两个层次上认识共降解过程具有重要的指导意义。     

渤海环流对近岸海域无机氮分布特征的影响

基于2017年渤海近岸海域无机氮监测数据和HYCOM数值模拟结果,分析了渤海环流对无机氮污染分布特征的影响,结果表明渤海无机氮的空间分布特征与其环流结构密切相关:受渤海环流的影响,在春、夏、秋季,无机氮含量高值区呈现不同的强度和范围;在辽东湾,与春季相比,夏季环流结构与春季相反、速度大于春季,盘锦、营口近岸海域夏季无机氮污染范围缩小、含量降低,在锦州近岸海域亦出现高值;在渤海湾、莱州湾,与春季相比,夏季和秋季无机氮含量高值区范围缩小,无机氮含量等值线均随环流向高值中心扩展。     

Evolving remanufacturing strategies in China: an evolutionary game theory perspective

Environment, Development and Sustainability - Rapid pace of natural resource depletion and environment deterioration is a cause of concern worldwide. Remanufacturing offers a promising option for...     

关于近岸海域生态环境监测技术体系的探讨

在近岸海域环境管理从污染控制管理发展为生态环境综合管理的情况下,厘清近岸海域生态环境监测技术体系并加以完善十分必要。通过对中国环境监测和管理发展的梳理得出,中国近岸海域生态环境监测技术体系在生态环境、污染和损害等方面已有一定的基础;研究国内外环境监测和管理的发展趋势发现,中国近岸海域生态环境监测技术体系在河口区域、生态恢复力、风险源、灾害、海域使用影响、湿地损害、生物入侵、环境风险源方面需要不断完善,质量保证和质量控制方面也需要加强。     

废弃电器电子产品绿色回收工艺及集中处理案例研究

从废弃电器电子产品资源化的潜在价值、产业政策、环保政策等方面,分析了废弃电器电子产品回收及资源化基地建设的必要性。重点论述了大宗废弃电器电子产品的资源化方法及工艺,同时说明了这些技术及工艺应用的优缺点、产污环节及其控制方式。以佛山市废弃电器电子产品绿色回收拆解及资源循环利用示范基地为例,分析了废旧家电集中处理的可行性和优越性,同时介绍了该基地的建设情况、经济效益和环境效益。该基地的实施为其他城市同类废物回收提供了一个借鉴模板。     

深圳河典型内分泌干扰物分布和季节变化规律研究

2011年6月至2012年5月在深圳河沿程采集水样,采用固相萃取一氮吹一衍生化的预处理方法和气相色谱/质谱联用法,对壬基酚(NP)、辛基酚(OP)、双酚A(BPA)、雌酮(E1)、雌二醇(E2)、17α-雌二醇(17α-E2)、雌三醇(E3)、雌炔醇(EE2)等8种内分泌干扰物(EDCs)在深圳河的浓度分布和时空变化规律进行了研究.同时通过主成分分析考察了EDCs与常规水质污染物的关系.结果表明,NP、BPA、E1、E3、EE2在深圳河各河段均有检出,而OP、17α-E2、E2的检出率均低于20％,EDCs主要来源是NP和BPA;深圳河旱季和雨季EDCs的浓度变化大,其中NP浓度表现出旱季高雨季低的规律,旱季浓度是雨季的1.74～5.63倍,但BPA和3种甾醇类雌激素的浓度呈现出了雨季高旱季低的相反变化规律,这应该与污水处理厂雨季污水溢流有关;通过主成分分析发现,BPA与DO存在明显的负相关关系,生物作用可能在BPA去除和甾醇类雌激素转化中起到了重要作用,具体机制还有待进一步研究.     

Mechanisms of photosynthetic inactivation on growth suppression of Microcystis aeruginosa under UV-C stress

This study aims to investigate the effects of UV-C irradiation on photosynthetic processes of Microcystis aeruginosa to unravel the mechanism(s) involved in how and in what ways UV-C mediates growth suppression and cellular recovery. Changes in the concentration of photosynthetic pigments, photochemical efficiency, PS II core protein (D1) content, and the coding genes expressions were measured. The results indicate that UV-C doses at 20–200 mJ cm⁻² lead to rapid reduction in gene expression of both psbA (for D1) and cpc (for phycocyanin), but the suppression was short term and recoverable within 3 d of post-UV incubation. Conversely, UV-C doses at ?50 mJ cm⁻² could induce marked decline in photochemical efficiency (represented by the optimal PS II quantum yield, F_V/F_M, and the effective PS II quantum yield, Y) as well as decreases in D1 content and water soluble pigments (phycoerythrins, phycocyanins, allophycocyanins) in M. aeruginosa during the post UV-C incubation period. The results suggest that interruption of both the light energy harvesting apparatus (especially the water soluble pigments) and the photochemical process mainly accounted for the growth suppression effect in UV-C irradiated M. aeruginosa.     

电动力学技术强化原位生物修复研究进展

介绍了利用电动力学技术强化土壤及地下水原位生物修复的原理和最新进展。电动力学强化的基本原理是利用电渗析、电迁移和电泳等电动力学效应加速污染环境中有机污染物和微生物运动,注入营养物、电子受体或活性微生物,或者利用电极反应和电流热效应为地下生物降解创造有利条件。研究表明．电动力学技术能有效地强化原位生物修复,而且该技术不破环生态环境．安装和操作简单,成本低廉．有广泛的应用前景。