Green Projects

Green Projects

The City of Riverside is committed to making our town a greener place to live by supporting renewable energy, responsible purchasing and design, and sustainable practices. The Riverside Water Quality Control Plant (RWQCP) has invested in and established several green projects designed to use byproducts of the sewage treatment process to produce energy.



Wastewater treatment at the RWQCP involves anaerobic digestion where, in the absence of oxygen, bacteria digest residual solids and create methane gas as a byproduct.

This gas is mixed with a small percentage of natural gas to fuel three Caterpillar internal-combustion reciprocating engines that run generators, each of which is rated to produce 1.1 megawatts.

Heat produced by the operation of the engines is used to heat the digesters for optimum performance in the generation of gas. The generated electricity is used in various processes throughout the treatment plant.



The Riverside Water Quality Control Plant (RWQCP) generates about 100 Wet Tons per Day (WTPD) of Class B digester sludge (“biosolids”).

Our biosolids are used in two ways:

  1. Biosolids are safely applied to farmland in Arizona where they act as a beneficial amendment to farmland and an environmentally-friendly alternative to petroleum-based and chemical fertilizers.
  2. Biosolids are sent to Nursery Products, LLC, a composting facility in Helendale, CA where biosolids are combined with green waste to generate Class A compost. The compost is then used by farmers to provide essential nutrients to their crops without chemical fertilizers, while reducing water usage and improving soil quality.