Efficiency of a Bed Biofilm Reactor Using a LECA Carrier to Treat Hospital Wastewater

Hospital wastewater is of great environmental concern because it contains a variety of hazardous microbial and chemical substances. This study aims to investigate the efficiency of a moving bed biofilm reactor (MBBR) with a light expanded clay aggregate (LECA) carrier for treating hospital wastewater. This pilot study used a Plexiglas reactor that had a volume of ۱۰۰ L, a continuous up- flow hydraulic regime, and a LECA carrier to test removal of chemical oxygen demand (COD) from wastewater in a public hospital. To assess MBBR efficiency, the study used retention times of ۸, ۱۲, and ۲۴ hours, filling percentages of ۳۰% and ۵۰%, and mixed liquor suspended solids (MLSSs) of ۱۰۰۰, ۳۰۰۰, and ۵۰۰۰ mg/L. The results indicated that using a single LECA carrier in an MBBR system was not sufficient to remove organic materials from hospital wastewater, because the carrier could not be completely suspended. After some modifications, consisting mainly of returning activated sludge, the system was ۸۳% efficient at removing COD using a LECA carrier at a retention time of ۲۴ hours, with ۵۰% filling, and ۵۰۰۰ mg/L of MLSS.