Abstract:
The objective of this study is to construct a data base of industrial wastewaters which contaminatedwith refractory wastes. Classification was done based on BOD to COD ratio of the influent andeffluent COD compared to official Effluent Standard. Wastewater analysis data of 11,652 type 3factorieswhich discharging into 4 major rivers, including Chao Praya, Ta Jean, Mae Klong, andBang Pa Kong rivers, obtained from the Department ofIndustrial Works, were used in this study.From preliminary reviews, only 931 factories have the BOD and COD of both influent and effluentwhich required for classification; however, they cover all 33 industrial types as specified by theDepartment of Industrial Works. Hence, these factories were used for data base construction.Wastewaters generated by these factories have the BOD to COD ratio in between 0.09 and 1.23.According to the information obtained, the most widely used biological process is aerobic processsuch as activated sludge and aerated lagoons, followed by the anaerobic process such as anaerobicponds and UASB. Combined treatment process was also found at some particular sites. Ifassuming that all wastewater treatment plants achieving their best performance, i.e., effluent BODcould comply with the Standard, there were still some in metal plating, dye and ink, chemicalreagent, and fertilizer and pesticide manufacturing industries which accounted for 20 percent of thetotal factories could not meet the COD Standard. As a result, special treatments beyond thebiological process are needed for these industrial types.