| Wastewater reuse as a sustained and stable resource is an effective way to alleviatethe water shortage. Chlorination disinfection is present widely used in the wastewatertreatment and reuse process as disinfection is a necessary step to guarantee safe water.But disinfection byproducts will be harm to water environment which generated fromthe reaction between chlorine and dissolved organic matter (DOM) in wastewater in therecycling process. The generation and transformation of disinfection by-products(DBPs) and DBPs precursors were studied and the best chlorination disinfectionconditions were obtained in wastewater treatment chlorine disinfection process. Theresults aimed to provide a theoretical basis to reduce the formation of DBPs inwastewater treatment process.The purposes of this research were to gain the distribution law of dissolved organicmatter of the different effluent in municipal wastewater treatment process and thegeneration of haloacetic acids (HAAs) and trihalomethanes (THMs) during the chlorinedisinfection, meanwhile to find the impact on disinfection byproducts precursorsthrough the measurement and analysis of sludge quality items such as DOC, UV254,THMs, HAAs, disinfection byproducts formation potential and3DEEM; To get the bestchlorination conditions and achieve optimization of wastewater reclamation disinfectionprocess, the field test was carried out with coagulation-sedimentation-filtration reactor.The results were as follows:1. The chlorine dosage had a significant effect on the formation of disinfectionbyproducts in municipal wastewater reclamation process during chlorine disinfection.The generation of THMs and HAAs increased along reaction process. In the total production, chloroform is mainly from trihalomethanes and haloacetic is mainly frombromine acid. The reason was caused by the hypobromous which has a strongerreplaced capacity generated from the presence of bromide ions in sewage.2. The data of wastewater quality items such as DOC, UV254, haloacetic acidsformation potential (HAAFP), trihalomethanes formation potential (THMFP) andfluorescence intensity of disinfection byproducts precursors had different degree ofreduction along reaction process. These results showed that a certain amount ofdissolved organic matter that might generate disinfection byproducts was reduced in thewastewater reclamation process. HAAFP is mainly composed of chlorinated acidformation potential, including mono-, dichloro-and trichloroacetic acid (MCAA, DCAA,TCAA), and THMFP is mainly composed of chloroform generation potential.Meanwhile, HAAFP and THMFP have decreased with the fluorescence intensitydecreases of humic acid and fulvic acid as humic acid and fulvic acid were the maindisinfection byproducts precursors. Further, there is a weak correlation between SUVAvalue and HAAFP when reclaimed water has a lower value of SUVA.3. The chlorine dosing points and the ratio of chlorine dosage of before and afterwere optimized with the targe of HAAs and THMs contents during the simulatedmunicipal wastewater chlorine disinfection treatment process. The results showed thatthe best chlorine dosing points are after precipitation and after filter, respectively. in thissituation the best ratio of the before and after chlorine dosage is1:1. Experimentscarried with sequential chlorination (i.e. short-term chlorine disinfection andchloramines disinfection) showed that it could effectively reduce DBPs formation.4. During the simulated reactor running the water quality indicators (includingchlorine and the total coliforms) meet the "standards of recycled water for landscapewater"(CJ/T95-2000). Under the best chlorination conditions of each group, theformation of trihalomethanes and haloacetic acids could be effectively controlled. |
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