UPGRADING OF SUSPENDED GROWTH PROCESS USING SUBMERGED MEDIA

Combined suspended / attached growth (CSAG) systems have been emerging recently to increase the efficiency of the existing systems. It takes its importance from high biomass concentrations that can be achieved within the system. The present study investigates the enhancement (if any) of convention al activated sludge (AS) process performance using attached media submerged in the aeration tank. The main purpose of this work is to find out the optimum combination of attached growth and suspended growth systems that achieve the best removal ratios (RR) of BOD and COD. Two models have been set up and run treating primary tr eated domestic wastewater. One of these two models has been run as an aeration tank w ithout any submerged media. This model has been utilized as a reference for the othe r model that runs as a combined suspended attached growth process. These two models worked parallel with the same influent wastewater and the same experimental conditions to investigate the effect of the added media volume in the aeration tank, the hy draulic retention time (HRT), and the sludge retention time (SRT), on the removing BOD 5, and COD. Ratios of submerged media volume to reactor volume ranges from 10 % to 60% have been tested. It was found that 30 % was the optimum rati o of media submerged in the reactor. The obtained results indicated that old an d over loaded plants can be improved using attached media to carry the extra hydraulic a nd organic loading rates.