CHAPTER 13 – Biological Processes: Biological processes represent a group of unit processes in which organisms transform or remove pollutants, known as biotic processes. Biological systems serve one or more functions in various stormwater treatment technologies such as protector of the treatment surface from erosion, enhancer of infiltration rates, and remover of pollutants.

Some of the questions considered in Chapter 13

• Can vegetated swales be expected to remove dissolved pollutants?
• Under what circumstances may emergent vegetation degrade rather than improve performance?
• Will wet ponds and constructed wetlands continue to remove pollutants over the long-term?
• Does vegetation harvesting enhance performance?
• What are the limitations of most studies conducted of constructed wetlands?
• How are wet ponds and wetlands sized to remove dissolved pollutants?
• What are the limitations and design criteria for cold and semi-arid climates?
• Why base flows may degrade the performance of wet ponds and wetlands?
• Does the drying of a wet pool adversely affect performance?
• Do wet ponds and wetlands perform more poorly in cold climate regions?

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