WASTEWATER TREATMENT PLANT

The Paso Robles Wastewater Treatment Plant was originally built in 1954. It is presently designed to handle a maximum capacity of 4.9 mgd; currently the City uses 2.8 mgd. The wastewater treatment plant treated 1.021 billion gallons of wastewater in 2002.  There are many projects in process, either design or construction, to upgrade the wastewater treatment plant and facilities throughout the City.

Eighteen hundred tons of bio-solids were produced by the treatment plant and used at the City landfill to supplement landscape soil. The term “bio-solids” is only applied to treated municipal sewage sludge. Bio-solids are the treated organic residue or sludge from municipal wastewater treatment. Raw sludge is separated from the wastewater and treated in digesters. Digesters are large enclosed vessels that use a temperature-controlled anaerobic biological process to convert raw sludge into a more stable sludge. This more stable sludge is then pumped to the sludge drying beds for final treatment. Here the water content is removed by evaporation or is pumped back to the headwork’s. This treatment process destroys pathogenic (disease-causing) organisms and produces stabilized, nutrient-rich, organic humus. The resulting bio-solids is collected and transported to the landfill for final disposal where it is used as a soil amendment in the final landfill cover.