Treatment Process Slideshow

  • Various communities on the Monterey Peninsula send their wastewater to the M1W treatment and recycling facilities in Marina where much of it is turned into safe water and used to irrigate farmland in Castroville.

  • Headworks: Large items such as rags and sticks are removed and sand and grit are screened out of wastewater.

  • Primary Clarifiers: Small particles that settle to the bottom or float to the top are skimmed and removed.

  • Anaerobic Digesters: Bacteria are used to convert the thickened solids to carbon dioxide, water, methane gas and a fertilizer material called biosolids.

  • Cogeneration Plant: Methane gas, a digester biproduct, is used to generate enough electricity to power the entire secondary treatment plant saving $10,000 per month in power costs.

  • Trickling Filters: Wastewater is sprayed onto plastic sheets covered with helpful bacteria that clean the water as they feed.

  • Bioflocculation Basins: Wastewater and large amounts of air are mixed with small microscopic organisms that remove dissolved material as they feed.

  • Secondary Clarifiers: Bioflocculation organisms settle to the bottom and are removed, leaving clean water at the top. This water is piped to the recycling facility or is discharged into the Bay.

  • Flocculation Basins: Chemicals are added that cause any remaining organic contaminants to clump together.

  • Filters: Solids that were formed in the flocculation basins are trapped in beds of pea gravel, sand, and anthracite coal.

  • Chlorine Contact Tanks: The wastewater is disinfected for at least 2 hours so it is safe for crop irrigation. Sulfur dioxide can be added to remove excess chlorine.



Changing Wastewater into Safe Water

Our facility is very similar to a River-in-a-Box, using natural processes, but in a large way and a lot faster. The RTP can recycle all the water it gets in only 12 hours!

Wastewater entering the Regional Treatment Plant (RTP) from homes and businesses passes through primary, secondary, and tertiary treatment processes that clarify and extract sediment.

Browse the slideshow for a general description of the treatment processes. Then visit the following pages for further information.

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