Synthetic urban wastewater treatment by an activated sludge reactor: Evolution of bacterial biomass and purifying efficiency

The present study aims to assess the evolution of biomass growth and the performances of an activated sludge pilot plant treating a synthetic urban wastewater. The activated sludge pilot plant used in this experiment reproduces the main principles of biological treatment using activated sludge process. The samples were collected every working day from the inlet, the outlet and in the bioreactor. The parameters monitored according to standards methods are: biomass growth, total suspended solids (TSS), volatile suspended solids (VSS), organic load (BOD5 and COD) and nutrients (nitrogen and phosphorus). Results showed a successful growth of the biomass that reached 1.62±0.88 gTSS/L and 1.30±0.77 gVSS/L. The activated sludge pilot plant performances in term of TSS, Turbidity, BOD_5 and CODT average removal efficiencies exceeded the expected performances and reached 90.6%, 91.5%, 83.6% and 90.8%, respectively. Although, the final effluent measured parameters concentrations were bellow and or close to design criteria of the pilot plant and the Moroccan applied discharge standards. Overall, the results obtained from this experimental study suggest that the activated sludge pilot plant has performed adequately under conditions equal to or less than its original design capacity and complained with the Moroccan applied discharge standards.