Primary Treatment - Settling and screening that separates sewage solids from liquid waste. Secondary Treatment - Introduction of bacteria which bind to the remaining solids and aid in their removal. The liquid wastewater is also partially disinfected. Tertiary Treatment - Full disinfection of liquid waste. Methods include chlorination and ozonation.
Tertiary treatment produces drinkable water and is required for discharge into fresh water bodies.
Sludge - The solid matter removed during the sewage treatment process. Also known as biosolids. Storm drains can carry a variety of substances such as sediments, fecal waste, metals, bacteria, oil, and antifreeze which enter the system through runoff, deliberate dumping, or spills. In Los Angeles County, this water picks up large amounts of pollutants in the storm drain system before reaching the beach. Suspended Solids - The small particles of solid matter in any water sample which are suspended.