A struvite reactor was installed in 2012, which recovers phosphorous from the wastewater. The reactor reduces the amount of phosphorus in the plants’ effluent to meet permit nutrient requirements, and is converted to fertilizer for beneficial re-use.
Methane biogas is recovered and used to sustainably operate wastewater treatment plant (WWTP) systems, including boilers, digesters and building heat. The biosolids dryer to be constructed in 2014/2015 will operate using methane biogas.
New boilers were installed in 2013. Water heat from the boilers is utilized to heat the digesters and WWTP buildings, using existing plumbing infrastructure. It is also used to heat new processes including the Industrial Waste Bioreactor.
The Industrial Waste Bioreactor was commissioned in 2013 to separately treat high strength food processing wastewater. The bioreactor increases WWTP capacity, reduces electrical costs, enables economic expansion, helps the environment, and keeps ratepayer costs down. By separately treating food processing waste, capacity for domestic treatment is significantly improved. Reductions in power consumption may save up to $10,000 per month when using this process compared to treating these industrial wastes through the domestic treatment process. Facilities like breweries, wineries, cider presses and other food processing industries are encouraged to locate in Yakima and benefit from the bioreactor. Phosphorous is being removed by the process, which improves the quality of the Yakima River. All these benefits will serve to stabilize rates for ratepayers over the long term.
A Biosolids Dryer will be installed in 2014/2015 to convert 8,500 tons of class B biosolids to approximately 1,800 tons of Class A fertilizer. The dryer will sustainably operate on methane biogas recovered from the WWTP processes. The dryer will reduce biosolids volume by at least 80%. The Class A Exceptional fertilizer resource will be recovered for beneficial use.