TREATMENT OF MEAT-PROCESSING WASTEWATER WITH A FULL-SCALE, LOW-COST SAND/GRAVEL BIOREACTOR SYSTEM

A full-scale sand/gravel bioreactor system was constructed to treat turkey processing wastewater. The system was designed to treat 757,000 L day(-1) at a surface application rate of 6 cm day(-1). Twelve 25 x 55 m sand bioreactors cover 1.6 ha on the plant property site. Construction cost was $1,426,000 (2011-2012) and operating costs were $57,600 per year. Normalized to volume of wastewater treatment, the estimated (2013) capital and operation cost is $1.03 m(-3). The plant began discharging effluent in 2013. Throughout 30 months, the plant has met all effluent requirements for CBOD5, TSS, and fat, oil, and grease (FOG). FOG was always below the detection level of 5 mg L-1 in the treated effluent. Ammonia is removed by the sand/gravel bioreactors through the summer months. During the winter/spring months, supplemental ammonia removal with an ion-exchange system is used to meet effluent standards. The low cost of the sand bioreactor system makes it suitable for small-scale meat processors.