Biosolids rotary press and truck loading operation Biosolids are the nutrient-rich solid organic matter recovered from the wastewater treatment process. SACWSD produces Class B Biosolids which meet EPA and State regulations for land application.
Biosolids undergo a two-stage biological digestion process that chemically stabilizes the material and reduces pathogens (disease-causing bacteria, viruses and parasites) and odor. The biosolids are then put through a rotary press to squeeze out the water. The pressed biosolids are then transported to agricultural fields and applied. They benefit the soil by providing organic content as well as nitrogen and phosphorus that plants need.