Study On The Treatment Of Ammonia Nitrogen In Pesticide Wastewater By Pressurized Air Flotation + Sodium Hypochlorite Oxidation

A Jiangxi pesticide plant’s production wastewater mainly includes Do-win production wastewater, jiatuo workshop production wastewater, isopropyl ester workshop production wastewater.Do-win production wastewater mainly comes from the crystal filter, exhaust gas treatment process, jiatuo workshop production wastewater mainly comes from the products’ washing and drying process,and also comes from waste gas treatment process, isopropyl ester production wastewater mainly comes from the waste gas absorption and treatment process.After pretreatment three wastewater were mixed to be treat as comprehensive wastewater, pesticide wastewater with high concentration mainly contains monomethylamine、chloroform、Do-win oxime,、methyl ester、methyl isothiocyanate,COD of the wastewater is 5000mg/L,pH is 8-9,SS is 150mg/L,ammonia nitrogen is 150mg/L.The original wastewater treatment process is "Fenton oxidation and hydrolysis acidification tank and sedimentation tank +BIOFOR tank ", the quality of treated wastewater were:pH=6-9,CODcr=80mg/L,BOD5=5mg/L, SS=10mg/L,ammonia nitrogen =48mg/L, therefore, in addition to ammonia, other indicators are in line with the " integrated wastewater discharge standard "( GB8978-1996) in a standard.This study was for transformation which was based on the original process, taking into account the continuity of the process, in the end to join the " process of treatment facilities in pressurized dissolved air flotation + sodium hypochlorite oxidation method ".The optimum reaction conditions of pressurized dissolved air flotation are that wastewater’s pH is 11,flow is 20L/h, reflux ratio is 50%,the dissolved gas pressure is 0.4MPa, Hydraulic retention time is 8h,the pesticide wastewater by pressurized dissolved air flotation process, ammonia concentration can be reduced to 60mg/L, the removal rate of ammonia nitrogen can reach 60%.The optimum reaction conditions of sodium hypochlorite oxidation method is: NaClO dosage 7.5mL/L wastewater, pH=8, mechanical stirring method, the reaction time is 30 min, the pressurized dissolved air flotation treatment of pesticide wastewater by sodium hypochlorite oxidation method, ammonia concentration can be reduced to 0.1mg/ L, the removal rate of ammonia nitrogen is 99.8%, the concentration of ammonia nitrogen the effluent meet the " integrated wastewater discharge standard "(GB8978-1996) in a standard. In practical engineering,because mixing causes incomplete, the reaction time is more than 30 minutes.In a word, to join the " process of pressurized dissolved air flotation + sodium hypochlorite oxidation method " at the end of the treatment, the concentration of ammonia nitrogen in wastewater is decreased from 63mg/L to 0.1mg/L, the emission concentration can reach the discharge standard of relevant countries.