Modeling HAA biodegradation in biofilters and distribution systems

A computer simulation which has been used to predict the working of three haloacetic acids (HAAs) (MCAA, DCAA, and TCAA) along a water distribution system and within a biologically active filter is discussed. The loss of HAAs in distribution systems and in biologically active filters was modeled using the integrated form of the one-dimensional plug- flow reactor equation. Spreadsheet calculations were performed using a one-dimensional plug-flow reactor model and experimentally determined (and estimated) kinetic parameters to investigate the potential for HAA biodegradation in distribution systems and biologically active filters. Removals of MCAA and TCAA were consistently less than that of DCAA because of slower biodegradation kinetics. Overall, the model calculations suggested that biodegradation is likely to be an important loss process for HAAs in biologically active filters and not likely to play a major role in most water distribution systems.