| With the rapid growth of economy and fast expansion of urban,environmental problems are getting worse,and the content of organic pollutants increases constantly.Eutrophication are widely distributed and algae blooms frequently,which leads to the simultaneous exisistence of algae and various organic micro-pollutants in many drinking source waters.However,the efficiency of conventional drinking water treatment process on algae and organic pollutants removal is low,which is difficult to effectively guarantee the quality of water supply and a serious threat to the safety of drinking water.Thus,it is of great significance to develop technologies that could simultaneously enhance algae and organic micro-pollutants removal.In response to the above questions,the study developed a new technology that could remove algar and organic pollutants simultaneously by coagulation process enhanced by ultraviolet/persulfate(UV/PS)preoxidation process,and Microcystis aeruginosa and trichlorophenol(TCP)were selected as typical representatives to investigate the effects of algae and TCP simultaneous removal on the process.In addition,the safety of the technology was evaluated by investigating the influence on the formation of DBPs during subsequent chlorination.On basis of the works aforementioned,the performance of the pilot plant dynamic experiment using coagulation process enhanced by UV/PS preoxidation to treat surface algae-laden water was also carried out.The main research contents and results are as follows:(1)UV/PS preoxidation could reduce zeta potential of algal cells and change the cell size,which improves the efficiency of coagulation process on the algal removal,and TCP was completely removed after UV/PS preoxidation treatment.The optimum dosage of PS was 100 mg/L and preoxidation time was 9 min,.UV/PS preoxidation could destroy the integrity of algal cells,which resulted in the release of intracellular organic matter(IOM)of algae and leads to an increase in the precursors of carbon-containing disinfection by-products(C-DBPs)and nitrogen-containing disinfection by-products(N-DBPs).(2)UV/PS preoxidation could effectively improve the efficiency of treatment for Hanjiang river(HJ),Liangzihu lake(LZH),and Yezhuhu lake(YZH)actual algae-laden water on coagulation and sedimentation processes.Through spectral analysis,it was found that UV/PS preoxidation could oxidize and remove unsaturated structures in algae-laden water.After coagulation and sedimentation processes enhanced by UV/PS preoxidation,the formation of C-DBPs increased,while the formation of N-DBPs decreased.(3)The pilot plant with UV/PS preoxidation+coagulation+sedimentation+filtration was used to treat the algae-laden water in Liangzi Lake.The results showed that UV/PS preoxidation could improve the efficiency of actual water on coagulation under dynamic experimental conditions,and improve the removal rate of turbidity and Chl-a without influencing the effluent alkalinity,hardness and total aluminum content.The optimum dosage of PS,UV intensity,and preoxidation time were 60 mg/L,340?W/cm~2,and 9 min,respectively.It is concluded that the cumulative cost on the treatment of unit water volume using UV/PS preoxidation process during pilot-scale research was?0.412/m~3,of which the78.6%was pharmaceutical cost through economic calculation,In conclusion,UV/PS preoxidation could not only improve the coagulation efficiency on the removal of algae and TCP simultaneously,but also could dent the impact of compound pollution,which is an effective emergency program for algae removal and could effectively guarantee the quality of water supply.However,UV/PS preoxidation could destroy algae cells and release intracellular substances.And there is a certain risk of increasing the precursors of disinfection by-products,which requires further study. |
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