EVALUATION OF NITROGEN REMOVAL IN CARROUSEL SYSTEMS

A field study was conducted at the 55 MGD Dammam (Saudi Arabia) wastew ater treatment plant employing the carrousel system, to evaluate its o verall performance with particular emphasis on nitrogen removal. The r esults of the study showed that the plant achieved greater than 93% BO D removal, 99% ammonia reduction, and 93% TKN removal. The plant readi ly met the secondary effluent BOD5 requirement with an average BOD5 co ncentration of 8.2 mg l(-1), but barely satisfied the SS standard with effluent SS averaging around 29 mg l(-1). While the average total eff luent nitrogen was 4.4 mg l(-1), nitrification-denitrification account ed for about 45% of the total nitrogen removal. The system kinetics fo r BOD5 and ammonia removal conformed to the plug-flow first-order kine tic model. Kinetic parameters estimated in this study were well within literature values.