Selection of diazotrophic bacterial communities in biological sand filter mesocosms used for the treatment of phenolic-laden wastewater

Abstract

Agri effluents such as winery or olive mill wastewaters are characterized by high phenolic concentrations. These compounds are highly toxic and generally refractory to biodegradation. Biological sand filters (BSFs) represent inexpensive, environmentally friendly and sustainable wastewater treatment systems which rely vastly on microbial catabolic processes. This study aimed to assess the impact of increasing concentrations of synthetic phenolic-rich wastewater, ranging from 96 mg.L-1 gallic acid and 138 mg.L-1 vanillin (i.e. a total chemical oxygen demand (COD) of 234 mg.L-1) to 2400 mg.L-1 gallic acid and 3442 mg.L-1 vanillin (5842 mg COD.L-1), on bacterial communities from BSF mesocosms. This amendment procedure instigated adaptation of the bacterial communities, notably leading to the selection of a resistant diazotrophic community. This suggests that functional alterations in the bacterial communities in BSFs ensure provision of sufficient bioavailable nitrogen for the degradation of wastewater with a high C:N ratio.