Radically Increasing Treatment Facility Capacity of Low-Rate Anaerobic Treatment System with Minimal Investment

Dean Foods Company needed to increase the capacity of its pretreatment facility at its Garelick Farms facility in Lynn, Massachusetts. This facility included screening, equalization, and anaerobic contact process with gravity clarification. The initial plan was to replace the poor performing low-rate anaerobic treatment system with activated sludge treatment. Instead, a series of modest improvements to the pretreatment facility enabled it to grow in treatment capacity from the initial 4,000 kg/day Chemical Oxygen Demand (COD) rated capacity to 11,000 kg/day with micronutrient addition and other operational changes. Replacement of the degas tower and gravity clarifier with dissolved air flotation allowed the treatment capacity to increase from 11,000 kg/day to greater than 18,000 kg/day. These capacity increases not only have resulted in significant sewer surcharge savings but also in increased gas generation and energy recovery. The bottom-line of this story is that one can radically increase the treatment capacity of low-rate anaerobic treatment systems with minimal investment.