The Study On The Treatment Of Electroplating Reverse Osmosis Concentrated Wastewater In Electroplating Industrial Park

Electroplating industry in our country has become an indispensably important part in the system of modern industry, and a large number of electroplating wastewater that creates great harm to environment is produced from electroplating industry processes. In recent years, various regions have carried out more strictly emission standards according to need of local receiving water environmental management. And, local government requires that industrial wastewater reuse of electroplate corporations is not less than 60% for developing circular economy, saving the production water, reducing costs and reducing emissions. Thus, membrane treatment is an easy choice after different kinds of electroplating wastewater is treated,and the treatment of 35%-40% reverse osmosis concentrated water became a technical difficult problem.To the problem of electroplating wastewater reverse osmosis concentrated water in electroplating industrial park, this subject was supported by the industrial drainage to risk control technology integration and integrated demonstration of river water type, leading under the major science and technology projects of national water pollution control and management(2012Z-X07206-002), a combined process of ozone followed by biological aerated filter(BAF) was used to treat electroplating reverse osmosis(RO) concentrated wastewater. For treating electroplating reverse osmosis concentrated wastewater from a electroplating industrial park in Foshan Shunde, the wastewater initial p H, ozone concentration and reaction time on the ozone oxidation efficiency in the ozone oxidation unit were investigated, as well as the changes of some indicators in the process of oxidation. And the kinetics and reaction mechanism of ozone oxidation was discussed preliminarily. Then, the influences of hydraulic retention time(HRT) and gas/liquid ratio on the performance of the BAF reactor were evaluated for treating electroplating reverse osmosis concentrated wastewater after oxidized by ozone. Finally, according to disposal efficiency the feasibility of the combined process was discussed under the best operation conditions of the combined process of ozone followed by BAF.The ozone oxidation test showed that the operating conditions for the ozone reactor are optimized as follows: initial p H of 10, ozone concentration of 31.96mg/L, reaction time of 40 min. Under the best conditions of ozone oxidation, while the treating time was prolonged, p H value gradually reduced from10 to 8. At the same time, the TOC concentration also gradually reduced like the law of COD removal. And the biodegradability of wastewater increased from initial 0.08 to 0.32 which created good conditions for biochemical treatment. Through analysis and discussion, ozone oxidation reaction is first order reaction and the apparent kinetic equation is ln C=5.3662-0.0162 t. Ozone oxidation reaction is given priority to with indirect reaction, and active substance of oxidation reaction mainly is hydroxyl radicals(·OH).The BAF test showed that for the BAF rector the optical operating parameters are: HRT of 30 h and gas/liquid ratio of 5. Under the best condition and with influent COD concentration of 180-240mg/L, the COD removal efficiency reached 78.6% and the effluent COD concentration was reduced to 47mg/L which meeting the newly released discharge standard of electroplating wastewater.