Hybrid suspended growth bioreactor system for the nitrification, denitrification, and ammonia removal from beverage industry wastewater: Biokinetic modelling and optimization by response surface methodology

Abstract

To assess the feasibility of beverage industry wastewater (BIW) reuse, this study attempts to examine the effectiveness of a Hybrid Suspended Growth Bioreactor System (H-SGBS) for the treatment of BIW. The bioreactor comprises of an anoxic, aerobic, aerobic digester chamber, and a clarifier to settle sludge. Response surface methodology (RSM) was utilised to design the experiment and examine the impact of different operating variables. Hydraulic retention periods (HRT) of 1–3 days were adopted for H-SGBS with BIW concentrations of 20–100%. The results revealed that maximum NH4+-N removal of 94.26% was attained at 60% BIW and 2 d HRT. Therefore, further testing is not required. The ultimate effluent quality increased with the addition of an aerobic chamber to the bioreactor, meeting most environmental and economic requirements. Treating BIW using the first two chambers of H-SGBS was possible with an overall energy usage of 0.15 kWh/m3 and an operational cost of roughly 6.48 USD/m3. Consequently, using aerobic digester chamber, and a clarifier to settle sludge to remove NH4+-N from H-SGBS was a promising and cost-efficient strategy. It could also be termed as a useful and sustainable treatment process for BIW. The First order, Grau Second order, and Modified Stover-Kincannon models were utilised to assess substrate removal rates. The models that best fit the experimental data turned out to be the modified Stover-Kincannon (R2 = 0.97309) and Grau second order (R2 = 0.95838). Thus, it could be said that the H-SGBS has successfully removed contaminants while also degrading BIW in sludge. The findings of this study indicate that the recently developed H-SGBS with native mixed microorganisms can remediate contaminants released from the beverage industry. To further reduce the NH4+-N concentration, a tertiary treatment step might be necessary.