Biotreatment of drinking water

Conventional biofiltration refers to filtration processes where the filter comprises porous material that is colonized by indigenous microbial communities and where these microorganisms perform at least one of the essential functions of the filtration process. Biofilters such as granular active carbon (GAC) filters, rapid sand filters (RSFs), and slow sand filters (SSFs) are key processes in the biotreatment of drinking water in both industrialized and developing countries. The main purpose of biofiltration is the removal of biodegradable organic carbon, but a wide variety of possible filter configurations, together with a broad range of different water types and pretreatment methods, contribute to extremely diverse biofiltration performance results reported in literature. The biological component of all biofilters comprises indigenous bacteria that proliferate in biofilms at low nutrient concentrations. This chapter specifically focuses on the state of the art of engineered biofiltration systems (e.g., GAC, RSF, SSF) and investigates the key differences between these filter types from a microbiological perspective. Different methodologies for the analysis of organic carbon, particularly the bioavailable fractions, as well as for the analysis of biomass on granulated materials are discussed and compared. The final section highlights open questions and future research opportunities of this field.