Study On Operation Characteristics And Pollutant Removal Efficiency Of Dissolve Ozone Flotation Process

The traditional water treatment technology is facing severe challenges with the pollution of drinking water sources.How to guarantee the safety of urban water supply has been the goal pursued by all of us.The flotation separation technology is widely used especially for low temperature and low turbidity and high algae laden water.The paper put forward dissolve ozone flotation system which is using ozone as the source of air.Based on the analysis of four kinds of source water in Ji’nan,the operation parameters,operation characteristics and removal mechanism of the technology were discussed.The main contents and results are as follows:Analysis the conventional chemical index,volatile and semi volatile organic matter index,odour index,algae pollution index of the main drinking water source in Ji’nan.The results showed that four kinds of water are subject to different levels of organic pollution and algae pollution.According to four different types of water sources,the optimum conditions of dissolve ozone flotation are determined by the test.At the same time,the response surface method(RSM)analysis was selected to optimize the operating parameters.The results show that the Queshan reservoir water coagulant 4mg/L,floatation reflux ratio is 18%,the dosage of ozone 1.4mg/L;Yuqing lake reservoir water coagulant 4mg/L,floatation reflux ratio is 18%,the dosage of ozone 2.2mg/L;crouching tiger mountain reservoir water in the coagulant dosage 4mg/L,floatation reflux ratio 18%,the ozone dosage 1.8mg/L;Jiping canal in coagulant dosage 5mg/L,floatation reflux ratio is 17%,the dosage of ozone 2.0mg/L,air pressure value is 0.4~0.5MPa,has a good effect on the removal of pollutants.The removal efficiency of turbidity,organic pollutants and algae in 4 kinds of source water in Ji’nan was tested by ozone flotation combined system.Meanwhile,the removal efficiency of traditional dissolved air flotation process was compared.The test results show that the removal rate of turbidity,DOC,UV254,CODMn4 index,Queshan reservoir were 52.1%,21.4%,19.7%,15.4%;Yuqing lake reservoir is 47%,18.8%,26.6%,23.7%,57.2%;Wohushan reservoir 26.6%,23.2%,29.6%;70.4%,20.8% Ji Ping channel 31.5%,30.5%.The total removal rate of algae and chlorophyll a was 88.8% and 89.26%.The number of residual algae in the water decreased significantly after the treatment with ozone and air flotation.The mechanism of ozone removal by air flotation process is analyzed.Ozone mainly enhances the efficiency of flotation by two ways: oxidizing and decomposing organic matters and enhancing coagulation.Ozone-flotation has a good effect on the removal of macromolecular organic matter,and ozone can decompose macromolecule organic matter into small molecule organic matter.The results of fluorescence analysis show that ozone air flotation has a better removal effect on protein substances.The influence of ozone on coagulation effect shows that the particle size of air floatation is measured by Malvern 3000 E.The particle size of ozone air floatation is easier to float than that of traditional flotation particle size.