Effects of Ca(OH)2 assisted aluminum sulfate coagulation on the removal of humic acid and the formation potentials of tri-halomethanes and haloacetic acids in chlorination

The effects of addition of calcium hydroxide on aluminum sulphate(or alum) coagulation for removal of natural organic matter(NOM) and its subsequent effect on the formation potentials of two major types of regulated disinfection byproducts(DBPs),haloacetic acids(HAAs) and trihalomethanes(THMs),have been examined.The results revealed several noteworthy phenomena.At the optimal coagulation pH(i.e.6),the coagulation behavior of NOM water solutions versus alum dose,showed large variation and a consequent great change in the formation potentials of the DBPs at certain coagulant doses.However,with addition of a relatively small amount of Ca(OH) 2,although the zeta potential of coagulated flocs remained almost the same,NOM removal became more consistent with alum dose.Importantly,also the detrimental effect of charge reversal on NOM removal at the low coagulant dose disappeared.This resulted in a steady decrease in the formation potentials of DBPs as a function of the coagulant dose.Moreover,the addition of Ca(OH) 2 broadened the pH range of alum coagulation and promoted further reduction of the formation potentials of the DBPs.The enhancement effects of Ca(OH) 2 assisted alum coagulation are especially pronounced at pH 7 and 8.Finally,synchronous fluorescence spectra showed that the reduction in DBPs formation potential by Ca(OH) 2-assisted alum coagulation was connected to an enhanced removal of small hydrophobic and hydrophilic HA molecules.Ca(OH) 2-assistance of alum coagulation appeared to increase substantially the removal of the hydrophilic HA fraction responsible for HAAs formation,prompting further reduction of HAA formation potentials.     

An evaluation on the environmental consequences of residual CFCs from obsolete household refrigerators in China

Chlorofluorocarbons (CFCs) contained in household refrigerators consist mainly of CFC-11 and CFC-12, which will be eventually released into the environment. Consequentially, environmental releases of these refrigerants will lead to ozone depletion and contribute significantly to the greenhouse effect, if waste refrigerators are not disposed of properly. In the present paper, the potential release of residual CFCs and their substitutes from obsolete household refrigerators in China is examined, and their contributions to ozone depletion and greenhouse effect are compared with those of other recognized ozone-depleting substances (ODS) and greenhouse gases (GHGs). The results imply that annual potential amounts of released residual CFC-11 and CFC-12 will reach their maximums at 4600 and 2300 tons, respectively in 2011, and then decrease gradually to zero until 2020. Meanwhile, the amounts of their most widely used substitutes HCFC-141b and HFC-134a will keep increasing. Subsequently, the contribution ratio of these CFCs and their substitutes to ozone depletion will remain at 25% through 2011, and reach its peak value of 34% by 2018. The contribution to greenhouse effect will reach its peak value of 0.57% by 2010. Moreover, the contribution ratio of these CFCs to the total global release of CFCs will steadily increase, reaching its peak of 15% by 2018. Thus, this period from 2010 to 2018 is a crucial time during which residual CFCs and their substitutes from obsolete household refrigerators in China will contribute significantly to ozone depletion.     

水对公路工程的危害及公路建设对水环境的影响

水对公路的路基、路面、隧道等结构都会产生危害，而公路建设也会对沿线的地下水环境产生影响。进行公路排水对提高使用道路的寿命和服务质量有积极的作用，但也应考虑公路建设对地下水和地表水环境的影响。     

小型燃油锅炉NOx的排放特征与管理控制

以68台燃油锅炉（≤10.5 MW）NO_x排放实测数据为基础，通过统计分析方法，研究了NO_x的排放特征；通过对比分析，探讨了我国燃油锅炉NO_x排放控制与管理现状，讨论了进一步加强我国燃油锅炉NO_x排放管理控制的可能性与可行性，并提出了相应的管理控制建议。结果表明，NO_x平均排放浓度为318.2 mg/m³，     

热处理对脱水污泥溶解特性及厌氧消化性能的影响

分别对脱水污泥在100、130和170℃条件下进行热处理,研究热处理对脱水污泥溶解特性的影响。此外,在半连续式完全混合反应器中进行厌氧消化实验研究不同热处理污泥的厌氧消化性能。实验结果表明,在100、130和170℃条件下,污泥COD溶解率由处理前的5.23%分别提高至20.08%、22.50%和27.20%,脱水污泥热处理规律和效果与高含水率污泥(总固体含量<5%)基本一致。经130℃2 h和170℃30 min高温热处理后污泥甲烷产率显著提高,较原泥分别提高24.64%和38.61%,沼气中甲烷含量稍有降低。     

气候变化和人类活动对天津海岸带影响综述

21世纪全球海平面上升和区域地面沉降叠加所致的相对海平面上升速率存在加快趋势,将加剧天津沿海地区风暴潮、洪涝灾害和土地淹没的危害,影响沿海地区的城市抗灾功能、建筑物安全及生态资源。为此,本文综合讨论了气候变化导致的海平面上升和地面沉降对天津沿海风暴潮、海岸侵蚀以及港口码头的影响。建议滨海新区建设要高度重视海洋灾害的监测预警,提高沿海地区防潮和防汛工程的设计标准和城市抗灾能力,以有效实现滨海新区经济和社会可持续发展。     

强化活性炭处理工艺去除焦化厂生化出水中的氰化物

以某焦化厂生化出水为研究对象,考寨了金属负载活性炭(简称负载炭)和Fenton氧化预处理等强化活性炭工艺对总氰化物(TCN)的去除效果.在TCN批式实验中,对负载炭的金属离子种类和固定方式进行了考察,同时研究了接触时间、DO对游离氰(KCN配水)、络合氰(K3Fe(CN)6配水)及焦化厂生化出水中TCN的去除效果.结果表明,负载金属离子可以有效提高活性炭对TCN的去除量,KI固定后的载铜活性炭对TCN的去除更有效.吸附作用在活性炭去除TCN过程中起着主要作用,同时TCN在活性炭表面也发生缓慢的催化氧化反应.在穿透实验中,采用了小型炭柱穿透和微型快速穿透实验方法,得到的TCN穿透曲线基本相同.含不同比例原煤炭和负载炭的小型炭柱处理经Fenton氧化预处理的焦化厂生化出水时,在18 d的启动阶段后形成生物活性炭柱,其出水能长期达到<城镇污水处理厂污染物排放标准>(GB 18918-2002)规定的要求.载铜话性炭可以提高活性炭工艺对TCN的去除能力,确保处理全程(57 d)出水的TCN达标.     

Measurement of semivolatile carbonaceous aerosols and its implications: A review

Measurement of carbonaceous aerosols is complicated by positive and negative artifacts. An organic denuder with high efficiency for removing gaseous organics is an effective approach to eliminate the positive artifact, and it is a precondition for the accurate determination of SVOC by an adsorbent backup filter. Evaluations of different configurations of the organic denuder, and SVOC determined by different denuder-based samplers, both integrated and semi-continuous, are reviewed. A new equation for determination of the denuder efficiency is estimated, considering the efficiency of removing both the gaseous organics that could be adsorbed by the quartz and the gaseous passing through the quartz that could be subsequently adsorbed by the backup adsorbent filter. The origin of OC on the backup quartz filter, behind either quartz or Teflon filter, is quantitatively evaluated by the denuder-based method based on the data published. The backup-OC is shown to be dominated by either gaseous organics passing through the front filter or the evaporated particulate organic carbon depending on the sampling environment.     

用废弃印刷线路板制备粒状活性炭

以废旧印刷线路板非金属分离物为前躯体,经热解、成型、炭化和水蒸汽活化制备粒状活性炭.研究了热解温度对残碳收率的影响,煤焦油配比对成型碳强度的影响,活化反应条件对活性炭烧蚀率、比表面积和碘吸附值的影响.结果表明,随着热解温度的提高残碳收率下降;随着煤焦油配比增大,成型碳的强度呈现先增大后减少的趋势,成型碳机械强度最大时的...     

中子辐射防护服的设计、结构与效果

系统地阐述了中子辐射防护服的设计依据、结构、式样及使用效果。表明这是一种能有效地屏蔽热中子和中能中子的防护器具,可用于许多场所。