Treatment Technology And Mechanism Of Arsenic Compound Polluted Wastewater

As a commonly used fungicide in the breeding industry,arsanic acid（ASA）is often mixed in livestock and poultry feed.Although the parent compound of ASA is non-toxic and does not remain in the body of livestock and poultry,ASA is easily soluble in water.Or livestock and poultry manure migrates widely and is degraded during the migration and transformation process to produce extremely toxic inorganic arsenic-As（Ⅲ/Ⅴ）,which seriously endangers human health.Therefore,searching for suitable oxidants to simultaneously treat composite polluted wastewater containing organic arsenic and inorganic arsenic is one of the important issues in current environmental governance.Ferrate has attracted much attention because of its multiple functions such as oxidative degradation,flocculation and adsorption.Based on this,this article uses K₂Fe O₄as a multifunctional treatment agent,and uses ASA and As（Ⅲ）as typical representatives of organic and inorganic arsenic to discuss arsenic-containing composite polluted wastewater（100 mg/LASA+10 mg/LAs（Ⅲ））Technology and mechanism.The specific research results are as follows:1.Using K₂Fe O₄as the treatment agent,the effects of treatment time,K₂Fe O₄dosage,temperature,pH,alkaline substances and interfering substances on the removal of ASA and As（Ⅲ）under experimental conditions were explored,and the experiment obtained The best removal conditions are as follows:temperature is 20℃,iron-arsenic mass ratio is 2.5:1,pH=4,alkaline substance to adjust pH is Ca（OH）₂,reaction time is6 h,the highest removal rate of ASA is 77%,The highest removal rate of As（Ⅲ）is94%;2.The effect of interfering ions on arsenic composite polluted wastewater（100mg/LASA+10 mg/LAs（Ⅲ））:C₆H₈O₇,NH₃·H₂O,Na₂SO₄with a concentration of 1200mg/L were added for interference experiments,and the results showed that,The SO₄^2-in Na₂SO₄can promote the removal of ASA and As（Ⅲ）,and the removal rate can reach 96%and 94%.NH₃·H₂O and C₆H₈O₇have a large interference on the removal rate of ASA,and the removal rate has dropped by 10%and 13%,respectively.,It has relatively little influence on the removal rate of As（Ⅲ）,dropping by 3%and 10%respectively;3.Explained the mechanism of K₂Fe O₄to remove compound polluted wastewater,and fitted it through oxidation kinetics,which was in line with the secondary reaction kinetic model.The solid samples obtained after the reaction were characterized by scanning electron microscopy and infrared spectroscopy.The results showed that new precipitates were formed in the reaction,and ASA was degraded by K₂Fe O₄without being adsorbed;that is,ASA was oxidized and degraded by K₂Fe O₄to form secondary small particles.Molecular organic products and As（Ⅲ）,As（Ⅲ）continue to be oxidized to As（Ⅴ）.The hydrolyzate of K₂Fe O₄can adsorb As（Ⅲ）and As（Ⅴ）,so as to achieve the co-removal of organic arsenic and inorganic arsenic.purpose;4.Taking the COD（Chemical Oxygen Demand）and TOC（Total Organic Carbon）of the simulated composite organic arsenic and inorganic arsenic composite polluted wastewater in the laboratory as the research object,analyze the changes of COD and TOC of the effluent under different experimental conditions:inhibition by alkaline conditions Mineralization;a decrease in temperature will promote mineralization.