Municipal sewage wastewater treatment by activated sludge process: results of a pilot scale study

Abstract

The objective of the current research was to perform an experimental pilot study of municipal sewage wastewater treatment by activated sludge process. To this end, the biomass growth, system performance, flocs stealliabilityand microbial hygienic parameters were evaluated and assessed. The results highlight an optimal growth of the biomass, which reached 4.83±0.25 g_TSS.l^-1 and 3.68±0.2 g_VSS.l^-1. The activated sludge performances in term of TSS, COD, BOD₅, TKN and TP were 92%, 94%, 97%, 85% and 16%, respectively. This value shows an efficient treatment of the wastewater organic pollution and nutrients by activated sludge pilot system. In addition, the treated effluent measured parameters concentrations were bellow Moroccan regulation for direct discharge into environment. The sludge volume index (SVI) average concentrations were in the range of 80 mL.g^-1 to 150 mL.g^-1, indicating the good folcs settleability during the experimental period. Concerning microbiological analysis, no significant reduction of all measured bacteria (p>0.05) was observed in the treated wastewater. Therefore, the concentrations of all bacteria remained practically stable after the treatment and were above Moroccan regulation guidelines for wastewater reuse in agriculture and WHO guidelines for the safe use of wastewater. The  results  obtained  from  this  pilot scale study  advocate  that  the  activated sludge pilot system has performed adequately under conditions equal to its original design criteria and complained with Moroccan applied discharge standards. On other hand, to reuse treated wastewater in agriculture a disinfection process is recommended to ovoid public health and environmental contamination.