Domestic waste management and recovery in Hong Kong

This article presents a review of the current municipal solid waste (MSW) and domestic waste generation and recovery situation in Hong Kong and identifies the factors affecting the waste generation rates. The results show that before 1997, MSW and domestic waste generation rates were driven by population growth and growth in the gross domestic product, with the latter having the larger effect. But recent waste generation data show poor correlation between waste generation rates and economic and population figures due to the increase in recycling efforts in the community. The results are also reported of a small-scale survey to explore the public attitude to waste recovery. The results show that most domestic householders have developed habits to carry out separation of waste at source for recycling, but the amount of recyclables recovered was low.     

Applicability of grid-net detection system for landfill leachate and diesel fuel release in the subsurface

The grid-net system estimating the electrical conductivity changes was evaluated as a potential detection system for the leakage of diesel fuel and landfill leachate. Aspects of electrical conductivity changes were varied upon the type of contaminant. The electrical conductivity in the homogeneous mixtures of soil and landfill leachate linearly increased with the ionic concentration of pore fluid, which became more significant at higher volumetric water contents. However, the electrical conductivity in soil/diesel fuel mixture decreased with diesel fuel content and it was more significant at lower water contents. The electrode spacing should be determined by considering the type of contaminant to enhance the electrode sensitivity especially when two-electrode sensors are to be used. The electrode sensitivity for landfill leachate was constantly maintained regardless of the electrode spacings while that for the diesel fuel significantly increased at smaller electrode spacings. This is possibly due to the fact that the insulating barrier effect of the diesel fuel in non-aqueous phase was less predominant at large electrode spacing because electrical current can form the round-about paths over the volume with relatively small diesel fuel content. The model test results showed that the grid-net detection system can be used to monitor the leakage from waste landfill and underground storage tank sites. However, for a successful application of the detection system in the field, data under various field conditions should be accumulated.     

Life cycle assessments of municipal solid waste management systems: A comparative analysis of selected peer-reviewed literature

Life cycle assessment (LCA) is a popular tool used to evaluate the environmental performance of municipal solid waste (MSW) management systems. Although reviews of LCAs of MSW have been undertaken to assess the validity of the ‘waste hierarchy,’ a recent review of the goal, scope and results of LCAs of mixed-material MSW management systems has yet to be performed. This paper is a comparative analysis of 20 process-based LCAs of MSW published between 2002 and 2008 in a total of 11 English-language peer-reviewed journals. It quantifies the methodological transparency of the studies and the frequency of use of particular system boundaries, types of data sources, environmental impact categories, impact weightings, economic valuations, sensitivity analyses, and LCA computer models. Net energy use (NEU), global warming potential (GWP), and acidification potential (AP) values for various types of MSW management systems are also compared using statistical indicators.The reviewed LCAs differ substantially in their system boundaries. Half or more of the LCAs either do not mention or are unclear in whether or not life cycle emissions from energy inputs or capital equipment are included in the calculation of results. Only four impact categories are common to more than half of the reviewed LCAs. The human and ecological toxicity impact categories are much less common than global warming potential, acidification, and eutrophication.A financial life cycle costing is present in eight of the reviewed LCAs, while an economic valuation of the environmental impacts is observed in five. Explicit sensitivity analyses are present in 4/20 of the studies, although many more LCAs evaluate the effects of varying model parameters by increasing the number of waste management scenarios. There is no consensus on whether or not to use the marginal or average source of electricity in calculating environmental impacts. Eight out of the 20 do not mention this source while the remaining LCAs are evenly split between the marginal and average electricity source. One quarter of the reviewed LCAs supply weighted results for the overall environmental performance of MSW management scenarios. All but one of these concurred with the ‘hierarchy of waste’ that the environmental performance of landfilling is lower than that of all the other treatment methods, and that thermal treatments are inferior to recycling.The comparative analyses of the NEU, GWP and AP results are based on 37, 45, and 42 MSW management scenarios, respectively. As measures of statistical dispersion, the interquartile ranges of the NEU, GWP and AP values are lowest for the landfilling (AP, NEU) and thermal treatment (GWP) scenarios. The results of the statistical analysis of the NEU, AP and GWP values appear to indicate that thermal treatment scenarios have a better environmental performance than landfilling, while the results for mixed treatment scenarios are less obvious. A comparison of the relative environmental performances of MSW treatment scenario types within each study did not provide a clear confirmation or repudiation of the waste hierarchy.This paper concludes that many recently published LCAs do not ensure that the methodological assumptions are made clear to the reader. Lack of transparency makes the results difficult to interpret, and hampers meaningful comparisons between the LCA results. A convergence in the adoption of particular assumptions that are more representative of MSW management systems would facilitate the comparison of the results.     

线路板生产废气的治理

通过实际工程设计参数的选择和运行条件的控制及试验研究 ,结果表明 :采用填料吸收塔处理线路板生产废气是经济和有效的 ,以 Na OH水溶液作吸收剂 ,经一级吸收处理废气中污染物去除 90 %以上 ,排气浓度小于无组织排放限值 ,再加上以醋酸和表面活性剂的水溶液作为吸收剂作二级吸收 ,废气中有机成分苯、甲苯、二甲苯、甲醛及铅的去除率可达 99.7%以上 ,总运行费小于 5 5元 /万 m3/h废气     

上海市郊大棚蔬菜的农药使用调查

通过对上海市郊大棚生产中农药使用情况的调查，揭示了上海市郊大棚蔬菜生产中存在的主要农药污染问题，主要表现在：所使用农药的结构不够合理，一些危险级农药仍在使用，而高效杀菌剂和除草剂的品种很少；大棚蔬菜的农药残留量较高，超标率可达１０％；食用受农药污染蔬菜的急性中毒事件时有发生，主要为绿叶蔬菜，农药主要是甲胺膦。     

白色污染的危害与防治

本文在综述白色污染形成原因、污染状况的基础上,介绍了我国目前解决白色污染的方法以及国外塑料废弃物的治理现状,同时探讨了白色污染防治中的问题,并提出了解决白色污染的对策。     

关于我国废干电池再生利用技术研究的几点思考

对我国废干电池再生利用技术研究提出了几点看法，认为我国废干电池再生利用技术既要注意环境无害化、资源化，还要考虑产业化和适应性问题，使我们的技术既有高的技术含量又符合我国国情。     

危险废物焚烧处置设施性能测试技术研究

危险废物集中焚烧处置是我国危险废物处置的最主要和最直接的方式之一。性能测试是检验危险废物焚烧处置设施能否达到正式运行要求的第一步,是保障焚烧处置设施安全稳定运行的必要手段,是颁发危险废物经营许可证的技术支撑。本文从标准废物选择及配置、性能测试指标体系建立、性能测试条件确定、性能测试监测技术研究、性能测试报告编制等方面开展适合我国国情的性能测试技术研究。     

庆大霉素-金霉素混合制药废水处理中试研究

运用厌氧-好氧-复配混凝技术进行了庆大霉素、金霉素混合制药废水处理中试研究,中试规模为日处理废水10~12t。在中试稳定运行时,进水的COD平均浓度为14218mg/L,出水的COD平均浓度低于制药行业排放标准(300mg/L)。