| With the past of time, our country in the development of economy was with high speed, at the same time, we aware more and more the serious environment pollution and must take measures at once. Although a various environment problems had been solved in different degrees, the problem is still outstanding. One of the most noticeable is the problem of water environment. In order to solve the problem of water environmental capacity reducing, and at the same time to better protect the health of the human beings, our state formulates a series of increasingly stringent environmental standards, especially for the secondary effluent before which discharge into receiving waters. And the microorganisms such as E. coli and Fecal escherichia coli emissions targets are added to the standers. Most urban sewage treatment plants in order to achieve the target that the Ministry of environmental protection and the Total bureau of national quality and quarantine inspection issued "the urban sewage treatment plant pollutant discharge standard"(GB18918-2002), and at the same time to solve the problem that the disinfection effect is not good, so it is necessary to know the most fitful adding quantity.This paper combined with the actual, and compared the several different disinfection processes in different ways. I have chosen the bleach disinfection process to explore on the actual situation of a urban sewage treatment plant of Zhengzhou. The main purpose is to master the actual situation of industrial bleaching powder, and find the optimal volume to reduce the cost of disinfection, and realize its functional target. This paper studied the main contents include:(1)Firstly, the paper analysed the fact from different angles to compare the several kinds of disinfection process, such as the disinfection of the principle, advantages and defects, disinfection of persistence, whether can cause secondary pollution, operability, maintenance equipment, the application of sewage treatment plant and so on.(2)Secondly, in industry, the disinfection ability of bleaching powder could be valued by active chlorine content, and which is the key to play a role in the composition, namely hypochlorite is equal to chlorine oxidation ability. The experiment used the iodine quantity method to measure the available chlorine content in industrial bleaching powder.(3)The experiment take the secondary effluent of sewage treatment plant as the research object,and through the monitoring data of the fecal escherichia coli in different time and different doses to explore the optimal dosing quantity of bleaching powder. In addition, the factors of pH and temperature were studied to check whether which could affect sterilization effect.The main results of the research showed as followed:(1)The advantages and disadvantages of different disinfection processes have their own different, in actual, we should according to the specific conditions to choose the size of the sewage treatment plant and other disinfection process.(2)Active chlorine is one of the important indicators, so we should master the bleach disinfection situation so that to measure active chlorine of bleaching powder.(3)As the growth of the disinfection contact time and the supernatant fluid volume increases, the fecal escherichia coli on the number of remaining less and less, and disinfection effect is more and more obvious. So when the cleaning liquid product is greater than 5 ml, contact time is more than 15 min, it can satisfy the urban sewage treatment plant pollutant discharge standard "(GB18918-2002) of 2002,and it can attain the level of a national emission standards.(4)Compared with normal temperature, the lower temperature condition should reduce the disinfection rate and make contact time be longer.(5)Supernatant of bleach disinfection effect associated with the pH value, disinfection effect of pH at 5.0 ~ 6.0 is better than 7.0 ~ 8.0, the higher the pH disinfection effect is bad. |
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