生物过程有可能去除常规处理可能无法有效去除的污染物，如可生物降解有机物、合成有机化合物、氨、硝酸盐、铁和锰。有机物和氨的生物氧化会减少分配系统中微生物再生的可用基质，减少味道和气味，并减少可形成消毒副产品的前体数量。生物去除某些污染物可以延长后续物理化学过程的使用时间或能力。在美国的水处理中，通常通过预氯化、严格清洗过滤介质和频繁反洗颗粒活性炭来削弱或阻止生物活性的发展。在欧洲使用含有微生物活性的培养基的实践经验是有利的。包括116个参考文献和表格。

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.