AWWA JAW24262

Biological processes have the potential to remove pollutants that may be ineffectively removed by conventional treatment, such as biodegradable organics, synthetic organic compounds, ammonia, nitrate, iron, and manganese. Biooxidation of organic matter and ammonia decreases available substrates for microbial regrowth in distribution systems, reduces tastes and odors, and decreases the amount of precursor available to form disinfection by-products. Biological removal of certain contaminants could extend the service time or capacity of subsequent physicochemical processes. In US water treatment, the practice is often to impair or preclude development of biological activity by prechlorination, rigorous scouring of filter media, and frequent backwashing of granular activated carbon. Practical experience in Europe with media containing microbial activity has been favorable. Includes 116 references, tables.