What does suspended growth processes in secondary treatment primarily target?

Suspended growth processes in secondary treatment primarily target biodegradable organic materials and ammonia nitrogen because these components are significant indicators of the organic pollution load in wastewater. During secondary treatment, microorganisms, particularly bacteria, are used to break down these organic substances.

The suspended growth process typically involves aeration tanks where a mixed liquor of wastewater and microorganisms is maintained in suspension and aerated to promote the growth of these bacteria. As the microorganisms consume the biodegradable organic materials, they convert them into biomass, carbon dioxide, and water. This biological activity is crucial for reducing the organic matter and nitrogen levels in the effluent, leading to cleaner water being discharged or further treated.

In addition to organic materials, ammonia nitrogen is also a target because it can be harmful to aquatic life if released into water bodies. The microbial processes facilitate its conversion into less harmful substances, thus aiding in the overall goal of secondary treatment to achieve significant reductions in pollutants prior to further treatment or discharge.