Optimization of surface area loading rate in moving bed biofilm reactor systems for wastewater treatment

Abstract

This thesis reviews Moving Bed Biofilm Reactor (MBBR) systems for wastewater treatment, focusing on Chemical Oxygen Demand (COD) and ammonia nitrogen (NH4-N) surface area removal rates. The study uses Partial Least Squares (PLS) Regression, and Fitted Regression, to identify key operational parameters and their impacts on system performance. It was found that Surface Area Loading Rate (SALR), and Organic Loading Rate (OLR) are significant predictors for COD and NH4-N removal rates. Specifically, optimizing NH4-N SALR, alongside, OLR, specific surface area (SSA) and hydraulic retention time (HRT), was shown to significantly enhances biofilm nitrification activity. Findings from this study highlighted media selection as a critical factor, with effective surface area proving essential for promoting removal activity and preventing pore clogging. Evaluations of different media characteristics demonstrated how media choice can impact overall system performance. Maintaining an optimal OLR proved crucial for maximizing COD and NH4-N removal rates in MBBRs. This study determined optimal conditions for achieving high COD and NH4-N surface area removal rates: for COD removal, an effective SALR of 19.96 g COD/m2.d, a COD concentration of 1.60 kg COD/m3, an SSA of 500 m2/m3, a media fill ratio (MFR) of 30%, and a 10-hour HRT were ideal. Optimal NH4-N removal was achieved with a SALR of 1.38 gNH4-N/m2.d, NH4-N concentration of 0.10 kgNH4-N/m3, an SSA of 500 m2/m3, an MFR of 45%, and a 10- hour HRT. For simultaneous COD and NH4-N removal, optimal conditions included an NH4-N SALR 1.60 gNH4-N/m2.d, an OLR of 3.2 kg COD/m3.d, NH4-N concentration of 0.1 kg NH4-N/m3, MFR of 50%, SSA of 500 m2/m3, and HRT of 10 hours. The work demonstrates that balancing operational parameters to prevent issues like clogging and substrate overloading is essential for maximizing organic removal and NH4-N transformation. The findings provide a framework for optimizing MBBR systems, making them more adaptable and efficient for diverse wastewater treatment applications. Future research should focus on developing innovative materials, technologies, and strategies to further optimize MBBR performance, thereby advancing sustainable wastewater management practices.