Purification performance of an aerobic biological fixed-culture process: a statistical analysis based on the Khénifra wastewater treatment plant (Morocco)

Abstract

This study evaluates the treatment efficiency of the bacterial bed process at Khenifra city's wastewater treatment plant (WWTP) and investigates the relationships between the physicochemical parameters that govern its performance. Physicochemical characterisation of the raw and treated wastewater was conducted by measuring total suspended solids (TSS), chemical oxygen demand (COD), five-day biochemical oxygen demand (BOD 5 ), pH, temperature and conductivity. Multivariate statistical analysis based on principal component analysis (PCA) was applied to 81 observations and 13 variables to explore parameter interactions. Additionally, a statistical model was developed to evaluate the impact of the temperature of the raw wastewater on the BOD 5 of the treated effluent. The treatment system exhibited high removal efficiencies, with reduction rates exceeding 90% for the main organic pollution indicators. PCA revealed strong correlations among key water quality parameters, providing insights into the bacterial bed process's overall functioning. The statistical model developed explained approximately 75% of the variability in the BOD 5 of treated water, highlighting the significant effect of influent temperature. The bacterial bed process demonstrated robust performance in the removal of organic matter at the Khenifra WWTP. Integrating multivariate and statistical modelling tools proved effective for process diagnosis and performance management, supporting their use in optimising wastewater treatment operations.