Assessing biomass diversity and performance of an activated sludge process treating saline table olive processing wastewater

Abstract

This study aimed to determine the effects of salinity on the biomass behavior and its diversity in activated sludge process (ASP) treating the table olive processing wastewater (TOPW), and to evaluate ASP performances under increased TOPW concentration feeding, the numerical abundance, diversity and activity of the biomass, removal efficiencies of chemical oxygen demand (COD), phenolic compounds, nitrogen and phosphorus were evaluated. Results showed that biomass growth is very high and became faster according to an increase in the percentage of TOPW feeding and reached 5.2 g_MLVSS l^-1. The specific oxygen uptake rate (SOUR) analysis revealed that salinity up to 10 g l^-1 provides an increase in biomass activity. SOUR reached a maximum of 20.3 g_O2 g_MLVSS^-1 h^-1. The increasing percentages of TOPW induce actually an evolution of microorganism's biodiversity; the microorganism communities were characterized by the abundance of halotolerant, Pseudomonas and Yeast genus that became the most abundant in the bioreactor as adaptation response against salinity. Furthermore, COD, phenolic compounds, nitrogen and phosphorus removal efficiencies attained 92.3%, 84.5%, 80% and 60%, respectively. A satisfactory release of extracellular polymeric substances is found to occur in the reactor with regard to increased saline TOPW, providing significant removal efficiencies and best settling of sludge.

Keywords: Activated sludge process; biomass diversity; extracellular polymeric substances; salinity; table olive processing wastewater.