Intrinsic kinetics for fixed bed bioreactor in hospital wastewater treatment

Variation in hospital wastewater (HWW) pollutants and differences with municipal wastewater (MWW), make the use of biokinetic coefficients obtained from activated sludge in the MWW treatment unprofitable for designing, modeling and evaluation of biological processes for HWW treatment. Since this study was conducted to evaluate the performance and biokinetic coefficients of a fixed bed bioreactor (FBBR) using rice husks as fixed media in HWW treatment, a new modified method was also proposed for biokinetic estimation in FBBR processes. For these purposes, five hydraulic retention times along with five sludge retention times were introduced to a pilot setup and the required data were attained. The performance process for chemical oxygen demand (COD) removal was significant (87.8–97.5%) in different conditions. The values of biokinetic coefficients k, K_s, Y and K_d were obtained as 2.42 (day⁻¹), 55.5 (mgCOD/L), 0.2929 (mgBiomass/mgCOD) and 0.0164 (day⁻¹), respectively. The rice husks with high surface area and high affinity for biomass accumulation on its surface are promising media for a green and environmentally friendly FBBR process. The kinetics parameters values are utilizable for modeling of FBBR using rice husks as fixed media in HWW treatment.