BERGEN COUNTY UTILITIES AUTHORITY DIGESTS CHEESE WHEY – GETS GAS AN ENERGY-COMMUNITY WIN-WIN

摘要

Bergen County Utilities Authority (BCUA) operates a 413 ML/d (109 MGD) wastewater treatment facility in Little Ferry, New Jersey. Digester gas produced in the anaerobic digesters is fed to a Combined Heat and Power (CHP) facility. Increasing digester gas production has the immediate benefit to BCUA of reducing purchased natural gas used to operate the Internal Combustion (IC) engines. Two major producers of cheese products are located just 5 km (3 miles) away. BCUA engaged a study team to perform bench scale testing to experimentally determine the potential for increased gas production from whey co-digestion as well as potential deleterious effects on digester operation. Bench testing consisted of Biochemical Methane Potential (BMP) and nutrient deficiency testing. Based on the encouraging bench testing findings, BCUA commenced a full-scale demonstration of CW co-digestion in October, 2010. Primary objectives were to confirm gas production potential and assess the impact on solids generation, which represents an off-setting cost to the savings from reduced natural gas purchases. Preliminary results, while qualitative, were quite favorable, and extended full scale testing has continued through June 2011. No significant adverse effects have been noted during extended testing. Drawing firm conclusions with respect to additional gas produced and net solids generated has proved challenging for reasons discussed below. The most demonstrable benefits are a “win-win” for the community. The cheese producers are no longer faced with intolerable costs for disposing of the whey. One has abandoned plans to relocate, and the other is now expanding production.