Control Of Algae And Its Products By Chlorine Dioxide Preoxidation For Algae Pollutioied Raw Water

Eutrophication has become one of the most important global environmental problems,water bloom is extreme eutrophication,growth of lake and reservoir water are often subject to bloom problems,algae outbreak problems sometimes appear.The high concentration algae in raw water will affect the removal effect of coagulation process,and cause a series of problems,such as clogging of filter,excessive filtration period and excessive content of algal toxins.Therefore,this paper aims at the problem of large algae density of raw water in some of water purification plant.The conditions of simulation ClO2 pre-oxidation,changes of ClO2 pre-oxidation on Microcystis aeruginosa killing effect,rules of the transformation of intracellular&extracellular organic matter were investigated.The removal efficiency of microcystins and disinfection by-products by ClO2 was studied to ensure the safety of the effluent from the water plant with eutrophic water as raw water.The reservoir water is used as the raw water in a water purification plant in Fuzhou.This experiment is based on the influent water quality,simulating the pre-oxidation condition of the water plant,and analyzing the control of algae and its products by ClO2 pre-oxidation under the condition of algae pollution.Microcystis aeruginosa was selected as the main algae for pre-oxidation experiment.By studying the cell process of ClO2 Pre-oxidation of algae and analyzing the change rule of organic matter content inside and outside the cell,it was concluded that cell disruption would release organic matter.The extracellular organic matter transformation study found that the intracellular mater such as amino acids,protein and fulvic acid as the representative of the region ?,? and ? was oxidized immediately after being released outside the cells by free ClO2.The humic substances represented by region V in extracellular organic matter will also be oxidized and degraded with the increase of dosage of ClO2.The content of MC-LR was mainly related to the amount of intracellular MC-LR release and the amount of extracellular MC-LR degradation.Under the influence of dosage,extracellular MC-LR content first increased and then decreased,but the intracellular MC-LR continued to decrease.Under the pre-oxidation time influence of extracellular MC-LR content increased first,then decreased slightly and tended to a stable trend,intracellular MC-LR content decreased to a certain extent basically unchanged;the intracellular MC-LR removal rate and removal rate of chlorophyll a has certain correlation.The Response Surface Methodology was used to optimize the operating parameter of pre-oxidation experiment.The optimized dosage of ClO2 pre-oxidation,pre-oxidation time and pH were 0.44 mg/L,12 min and 7.13 respectively.In these condition,the removal rate of algae can reach up to 90.98%,the concentration of chlorate in effluent can be as low as 0.41 mg/L,but the concentration of MC-LR was still high.Through the"UV-LED?precipitation?ClO2 pre-oxidation"process as the pre-oxidantion,the MC-LR and algae disinfection by-products can be controlled simultaneously.