Dairy wastes - waste or asset?

With the world-wide drive in developed countries to further improve treated wastewater quality, removal of the nutrients nitrogen and phosphorus has moved to the forefront. However, many treatment facilities do not have enough carbon (BOD) in the influent wastewater to achieve those goals. Much research and pilot testing has been performed to identify supplemental carbon sources to increase the degradable carbon to achieve nutrient removal goals. Many cities still have industrial pretreatment programs in place to charge industries for discharging excess BOD. Many treatment facilities searching for alternative carbon sources are located in these cities that still have pretreatment surcharge systems in place. To reduce these charges, many industries have implemented their own pretreatment facilities, which was the original purpose of implementing pretreatment surcharges. However, the carbon removed from the industrial wastewater by these pretreatment systems could often be an asset to the treatment works.

To further denitrify for alkalinity recovery to meet effluent pH limits, the J.D. Phillips Wastewater Reclamation Facility, located in Colorado Springs, Colorado required additional carbon. The search for an industry with a high BOD wastewater revealed a nearby dairy discharging whey into a nearby interceptor, on a sporadic basis, paying pretreatment charges ranging from $30,000 to $40,000 monthly. Simultaneously, the dairy approached the Utility to attempt to negotiate a reduced surcharge fee.

The successful use of acid whey, a waste product from the manufacture of cottage cheese, as a supplemental carbon source to increase denitrification, and the win-win solution developed for the Utility and the dairy is discussed. Recent field investigations into planned changes to Watercare Services trade waste regulations are also discussed.