Challenge

The Clearwater Cogeneration Wastewater Treatment Plant (CWWTP) in Corona, Calif., needed help processing 110 wet tons per calendar day (9167 pounds per hour) of municipal biosolids with a dry solids content of 16 percent.

Solution

Siemens Water Technologies supplied a convective thermal dryer.  Using a duel fuel source – natural gas and digester gas – the energy efficient biosolids dryer produces an end product that complies with USEPA 503 Part 40 rule for heat dried Class A biosolids.

Also, the drying facility is integrated with the city’s first power plant, and the existing wastewater treatment plant, allowing the City to generate enough electricity to operate the facility, and to provide 500° F waste heat to the biosolids dryer to preheat the dryer’s combustion air.  In addition, the system supplies the low-grade heat necessary to promote biological growth in the CWWTP’s digesters.

Results

Today, Corona’s electric utility satisfies its obligation to provide electric service from a portfolio of electric power purchases from the market as well as from the operation of its new Clearwater power plant.  The utility currently serves loads with about 25 MW of peak demand and is looking forward to providing reliable and competitive service to its continuously growing base of customers for years to come.

With the biosolids dryer working in harmony with the cogen facility, Corona is now reducing the volume of biosolids leaving Plant #1 by 80 percent, and is producing a Class A beneficial reuse product that can be applied to land for agricultural purposes as well as using it for an organic fuel.