A review on treatment of disinfection byproduct precursors by biological activated carbon process

Disinfection by-products (DBPs) in water systems have attracted increasing attention due to their toxic effects. Removal of precursors (mainly natural organic matter (NOM)) prior to the disinfection process has been recognized as the ideal strategy to control the DBP levels. Currently, biological activated carbon (BAC) process is a highly recommended and prevalent process for treatment of DBP precursors in advanced water treatment. This paper first introduces the fundamental knowledge of BAC process, including the history, basic principles, typical process flow, and basic operational parameters. Then, the selection of BAC process for treatment of DBP precursors is explained in detail based on the comparative analysis of dominant water treatment technologies from the aspects of mechanisms for NOM removal as well as the treatability of different groups of DBP precursors. Next, a thorough overview is presented to summarize the recent developments and breakthroughs in the removal of DBP precursors using BAC process, and the contents involved include effect of pre-BAC ozonation, removal performance of various DBP precursors, toxicity risk reduction, fractional analysis of NOM, effect of empty bed contact time (EBCT) and engineered biofiltration. Finally, some recommendations are made to strengthen current research and address the knowledge gaps, including the issues of microbial mechanisms, toxicity evaluation, degradation kinetics and microbial products. This paper presents a thorough overview to summarize the recent developments and breakthroughs in the removal of disinfection by-products (DBP) precursors using biological activated carbon (BAC) process, including the fundamental knowledge of BAC process, selection of BAC process for treatment of DBP precursors from the perspective of removal mechanisms, the comprehensive performance of BAC process in applications, and discussion of the current knowledge gaps and further evolution of BAC process for the treatment of DBP precursors.