Biobed biopurification systems with agroindustrial wastes to remove organic contaminants from water: microbiological and molecular aspects

Abstract

The continuous and uncontrolled release of organic pollutants such as pesticides and pharmaceutical and personal care products (PPCPs) originating from agricultural, industrial and urban activities affects water quality and can have a negative impact on ecosystems and human health. Currently, treatment of these wastewaters is expensive and the elimination of pollutants by conventional activated sludge treatment is insufficient. For this reason, it is necessary to develop affordable systems to prevent the transfer of these pollutants to the environment. Biopurification systems (BPSs) have proven to be a highly efficient technology to retain and degrade pesticides with diverse physicochemical characteristics. The effectiveness of BPSs is closely related to the composition of the biomixtures of which they are composed. Our research group has developed biomixtures based on low-cost agro-industrial wastes abundant in Spain, which are very efficient in the removal of pesticides and PPCPs even at high concentrations. However, despite the high decontamination potential of these systems little is known of the functioning of these BPSs at the microbiological and molecular level and how they could be improved to reduce the degradation time and elimination of even the most recalcitrant pollutants. Thus, the main objective of this thesis is to deepen our understanding of these aspects of BPSs and to improve their efficiency. For this purpose, the thesis has been oriented towards the following specific objectives: Objective 1: To determine the effects of PPCPs on bacterial viability and the microbial community structure of BPSs as well as to identify the main bacterial groups potentially involved in the degradation of these compounds. Objective 2: To develop a novel low-cost bioaugmentation strategy based on aqueous extracts rich in microorganisms to improve the elimination of pesticides and PPCPs as well as their main degradation products from BPSs and contaminated aqueous systems. Objective 3: To increase the dissipation rate of PPCPs and avoid the accumulation of their main metabolites in BPSs and in aqueous systems by bioaugmentation with exogenous degrading bacterial strains isolated from polluted environments.