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Optimization Of Drinking Water Advanced Treatment Process

Posted on:2006-07-09Degree:DoctorType:Dissertation
Country:ChinaCandidate:C H ZhangFull Text:PDF
GTID:1102360212482507Subject:Environmental Engineering
Abstract/Summary:PDF Full Text Request
The process of ozone-biological activated carbon which is one of advanced treatment technologies will be applied on a large scale in our country in the future, but there is still no enough experience in using it according to Chinese water characters. Systematical research was done acording to the raw water quality of Huangpu River from the mechanism and performance to remove polutant in this article, and draw the following conclusions:The analytical methods of trihalomethane formation potential(THMFP) and different kinds of DOC was improved, and a new method was established: respiration potential method.The research on ozonation technology showed that ozonation can decrease effectively organic pollutant burden and improve biodegradability of water. It was the first time to analyze the effect of ozone on dssovled organic matter and the biodegradability of water by determining different sorts of DOC. The experiment results indicated that for effluent of sand filter there were above 80% of NOM is belong to NB&ADOC, B&ADOCis about 10~13%, the amout of NA&BDOC and NRDOC were both below 5%. After ozonation the content of NB&ADOC, NA&BDOC and NRDOC all decrease but the amount of A&BDOC increase,moreover,the extent of increase for A&BDOC went up with the ozone dosage and contaction time. Under the optimal ozone conditions, the absolute content of B&ADOC increased by 49% and BDOC increased by 22% after ozonation, but proportion of BDOC to the total DOC (BDOC/DOC) increased 3-4%. It was also the first time to combine the molecular weight distribution of organic matter with water advanced treatment research, the molecular weight distribution for different effluent was analyzed and concluded that pretreatment process can effectively remove those organic pollutant whose molecular weight were above 3kD, and those pollutant whose molecular weight were above 10kD would be decomposed and those whose molecular weight were 3kD~1kD and below 0.5kD would increase after ozonation. BAC filter has a good removal ability for those organic matter whose molecular weight were 10kD~3kD, 3kD~1kD and <0.5kD, but the content would increase for those pollutant whose molecular weight was 100kD~10kD after BAC filter.The reduction of trihalomethane formation potential(THMFP) was discussed, which indicated that ozonation has a good removal for chlorofom and bromodichloromethane formation potential, but for dibromochloromethane formation potential the removal efficiency was undesirable and there was almost no removal for bromoform forming potential, Furthermore, when there was enough bromide in water, ozonation would have a promotion effect for bromoform formation potential. For the first time the removal mechanism of THMFP for ozone was demonstrated Combining differential UV spectroscopy and chemical reaction principle of ozone and chlorine. Under the optimal conditions for ozonation,change of water quality before and after ozonation and air was discussed from the following aspects: reducing pollutant burden and improving biodegradablity.The study on operational performance of BAC filter showed that there was no evident diference on biofilm forming time of BAC filters which following ozonation and air stage. BAC filter following ozone contacting column has a better performance than that following air contacting column. For the first time combining the analytical method of DOC composing and molecular weight distribution to study the removal mechanism and rule of organic matter for BAC filter in different runing phase. In addition, the removal mechanism and rule of THMFP for both of BAC filters in for seasons were discussed and found that BAC filter could reduce chloroform formation potential effectively, but couldn't effectivly remove bromizing trihalomethane, and the removal efficiency decline with further bromizing. the ralationship of main parameters of BAC filter (EBCT and filtration rate) and the removal ability were discussed , according to the correlative analysis for lots of data, it was concluded that EBCT was the key parameterand the relationship between EBCT and removal ability of filter was founded. Based on the study for backwashing technology, the most optimal backwashing strategy was established, on the base of which to compare the effective rule of backwashing on both of BAC filters.Effluent water quality of three treatment process which include"pretreatment process","pretreatment process + ozonation + BAC"and"pretreatment process + air+BAC"was dicussed, experimental results showed both of two advanced treatment process could improve water quality of pretreatment process. The process of"ozone + BAC"could averagely reduce about 31% of CODMn annually, and about 21% for the process of"air + BAC". For CODMn the former has a higher removal than the latter by about 10% and for UV254 by about 20%. The security of effluent water quality for both two advanced treatment process was assessed and results showed that the process of"ozone+BAC"has a better performance no matter the biostability or bacteria population for effluent. GC/MS test showed that total organic species number was reduced 59.7% and total spectrum aera was reduced 33% after treatment by"pretreatment+ozone+BAC+chlorination", on the other hand, total organic species number was reduced 44% and total spectrum aera was reduced 13% after treatment by"pretreatment+air+BAC+chlorination". All these demonstrated that the process"ozone + BAC"could produce higher quality of water than that of"air + BAC".It is first time in our country to analyze the generating mechanics and rules of trihalomethane by utlizing differential UV spectroscopy and founded a predictive model of forming trihalomethane. On the base of lots of data, the correlative analysis for TOC, CODMn and UV254 were done, and a model is established that can rapidly calculate TOC on the base of UV254.
Keywords/Search Tags:ozone, biological activated carbon, backwashing, THMFP, drinking water, micropollution, advanced treatment, the Huangpu River
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