Noppadon Suksawad creator Tran, Francis T. Chairperson Chongrak Polprasert Examination Committee Zhuang, Ya-Hui Examination committee Government of Australia Scholarship donor text series technical report th Bangkok Asian Institute of Technology 1992 continuing eng 98 p. A semi-pilot scale study was conducted to find the feasibility of airlift biocontactor which is a modified application of the waste activated sludge process.Gas liquid circulation between riser and downcomer pipe in deep shallow shape:the resulting high hydrostatic pressure to gether with very efficient mixing in the shaft provide extremely high oxygen transfer efficiencies.This performance ' I ' is required for refinery wastewater biodegradation . The airlift biocontactor unit was operated with contin uous feeding, hydraulic retention time at 24 and 10 hours was used for the first and second run(25 and 50 percent volume by volume of petroleum wastewater concentration which diluted with AIT domestic wastewater).For the third run,100 percent petroleum wasetwater concentration was fed at 24 ,10 and 6 hours of hydraulic retention time.In all these runs, the air flow rate for working air in the reactor was kept at 4 cfm. Organic loading was a less controllable factor. For all the runs ,it was found that the removal effi ciency of total chemical oxygen demand (TCOD) was above 85 percent,oil and phenol removal were above 90 percent and for ammonia nitrogen it was found above 97 percent.Performance of airlift biocontactor at 10 hours hydrualic retention time petroleum wastewater removal was the same as 24 hours hy draulic retention time , also petroleum concentration shows less effect on removal efficiency. -ii- The result show that this new technology can be applied effectively for petroleum wastewater treatment. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering Thesis (M.Eng.) - Asian Institute of Technology, 1992 Petroleum waste Biodegradation Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B16842 http://203.159.5.9/ait-thesis/detail.php?q=B16842 170399 20260817171428.0