Primary Treatment Process

Primary treatment is a simple mechanical process that uses bar screens, grit chambers, and settling tanks to remove trash and settleable solids from the wastewater.

Plant Influent
Wastewater from CVSan’s service area – the Treatment Plant’s influent – is collected from homes and businesses and pumped to the Treatment Plant through a network of 160 miles of sewer pipes.

Bar Screens
Bar screens act as coarse filters to remove rocks, sticks, and other large debris from the influent that might clog or damage equipment further downstream.

Grit Chamber
After passing through the bar screens, the wastewater enters the grit chamber, where heavy materials like sand and gravel settle out by gravity, are washed, and then trucked to a landfill.

Influent Pumps
The wastewater then enters the influent pumps and is lifted up to the primary clarifiers. From this point in the process on, the wastewater flows by gravity through the rest of the Treatment Plant, saving energy and helping keep the service rates low.

Primary Clarifiers
The wastewater enters the primary clarifiers, where suspended solids gradually settle to the bottom as raw sludge. The sludge, about 70% of the total solids, is mechanically collected and sent to the digesters – large structures that help break down organic matter into methane gas. Skimming blades remove scum and grease from the surface. The remaining liquid, called primary effluent, flows to the secondary treatment process.

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