污水处理工艺生命周期环境影响分析与比较

发布时间：2018-09-10 21:32

【摘要】：近年各省市陆续颁布地方污水排放标准,标准规定污水处理厂出水排放需达到一级A标准,污水处理厂普遍采取改进污水处理工艺或增加投药量的措施使出水水质达标,此做法会在降低末端环境影响的同时增加前端的能源生产所产生的环境影响,造成环境问题的转移。因此在出水水质达到一级A标准的基础上,不同污水处理工艺产生的环境影响如何,同一污水处理厂处理工艺改进前后环境影响变化如何,是政策实施背景下污水处理厂面临的问题。基于以上问题,本文运用基于输入-输出理论的生命周期评价(LifeCycle Assessment, LCA)方法,对不同污水处理工艺进行环境影响评价,为管理者提供决策支持,以利于区域环境的可持续发展。本文的主要内容有如下几方面：(1)运用Gabi 5.0软件建立污水处理厂A和B污水处理工艺运行阶段的生命周期评价模型,两个污水处理厂的处理工艺分别为曝气生物滤池工艺(Biological Aerated Filter,BAF)和恒水位序批式反应器处理工艺(Constant Waterlevel Sequencing Batch Reactors, CWSBR),将水回用因素考虑入评价中。研究结果表明,CWSBR工艺产生的环境影响小于曝气生物滤池工艺,其中酸化(AP)、温室效应(GWP)、人体潜在毒性(HTP)、海洋水生毒性(MAETP)差异明显,两种工艺的海洋生态毒性(MAE TP)结果值均为最大,臭氧层破坏(ODP)结果值较小,与其他类型相比可以忽略。(2)以污水处理厂A为研究对象,比较污水排放政策实施前后原工艺和新工艺环境影响变化,结果表明新工艺产生的环境影响高于原工艺,若要改善环境需采取资源回收措施。(3)本文提出净变量(Net Variable Quantity, NVQ)概念用以计算污水处理厂整体的环境影响变化,判断最优水回用率。以曝气生物滤池工艺为例,计算40%-100%之间不同水回用率情景下的净变量。结果表明,当水回用率在60%-70%之间时,净变量值由正值变为负值,即水回用率在此范围内时产生的正环境影响刚好补偿由于前端能源生产所产生的环境影响。
[Abstract]:In recent years, various provinces and cities have successively promulgated local sewage discharge standards, which stipulate that the effluent discharge of sewage treatment plants should meet the first class A standard. The sewage treatment plants generally adopt measures to improve the sewage treatment process or increase the dosage of drugs to make the effluent quality up to the standard. This approach can reduce the environmental impact at the end of the end while increasing the environmental impact of the front end energy production, resulting in the transfer of environmental problems. Therefore, on the basis of the effluent quality up to the first class A standard, what is the environmental impact of different wastewater treatment processes, and how does the environmental impact change before and after the process improvement of the same sewage treatment plant? Is the policy implementation background sewage treatment plant faces the question. Based on the above problems, this paper uses the life-cycle evaluation (LifeCycle Assessment, LCA) method based on the input-output theory to carry out the environmental impact assessment of different wastewater treatment processes, which provides decision support for the managers and is conducive to the sustainable development of the regional environment. The main contents of this paper are as follows: (1) the life cycle evaluation model of sewage treatment plant A and B wastewater treatment process is established by using Gabi 5.0 software. The treatment processes of two wastewater treatment plants are biological aerated filter process (Biological Aerated Filter,BAF) and constant water level sequencing batch reactor (Constant Waterlevel Sequencing Batch Reactors, CWSBR),). The factors of water reuse are taken into account in the evaluation. The results showed that the environmental impact of the CWSBR process was smaller than that of the biological aerated filter process, in which there was a significant difference in the potential toxicity of (AP), Greenhouse Effect (GWP), in marine and aquatic (MAETP), and the (MAE TP) value of the two processes was the largest. The result of ozone layer destruction (ODP) is small and can be ignored compared with other types. (2) taking sewage treatment plant A as the research object, the effects of the original process and the new process environment before and after the implementation of the sewage discharge policy are compared. The results show that the environmental impact of the new process is higher than that of the original process. In order to improve the environment, the measures of resource recovery should be taken. (3) the concept of net variable (Net Variable Quantity, NVQ) is proposed to calculate the environmental impact of the wastewater treatment plant as a whole and to judge the optimal rate of water reuse. Taking biological aerated filter as an example, the net variables under different water reuse rates between 40% and 100% were calculated. The results show that when the water reuse rate is between 60% and 70%, the net variable value changes from positive value to negative value, that is, the positive environmental impact of water reuse rate in this range compensates precisely for the environmental impact caused by front-end energy production.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;X820.3

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