Cost-Effective Solution for Reducing O&M Costs

The Sacramento Area Sewer District, or SacSewer, was required to upgrade its 181-million-gallon-per-day Sacramento Regional Wastewater Treatment Plant by 2021 to comply with a new permit that included nitrogen removal and California Title 22 filtration and disinfection. A new nitrifying sidestream treatment facility was included as one of many projects in Regional San’s EchoWater Program to reduce ammonia loads in the sidestream and thereby reduce effluent ammonia in the discharge. 

The nitrifying sidestream treatment facility is a cost-effective solution that drastically reduces plant operations and maintenance costs for a quick return on investment. Having a nitrifying sidestream treatment facility at the plant meant that the new biological nutrient removal facility could be designed smaller at a lower construction cost and carbon footprint, because the “loading rate” is much lower and peak ammonia loading events from sidestreams are avoided. Nitrifying sidestream treatment operations reduced the required aerobic capacity of biological nutrient removal by approximately 10%, resulting in savings of about $20 million on the biological nutrient removal project. 

Implementation of the nitrifying sidestream treatment facility allows nitrates produced in the facility to be sustainability applied to the influent, reducing the purchase of other inorganic nitrate chemicals, and significantly reducing the purchase of chlorine and the chemical Bioxoide®. The sustainable use of nutrients for odor control has reduced the sodium hypochlorite demand by about 8,500 gallons per day and is now saving Regional San about $2.4 million a year in chemical costs because the nitrifying sidestream treatment’s nitrate-rich effluent is successfully mitigating odors. This sustainable use reduces greenhouse gas emissions by reducing the trucking of chemicals into the Sacramento region, and eliminates the energy used by chemical manufacturers for producing the avoided liquid chlorine and nitrate chemicals.