Challenge
The client makes several types of confectionery products at its facility. Its wastewater was being treated in a dissolved air flotation (DAF) system, followed by a dual-tank sequencing batch reactor (SBR) activated sludge system. Waste sludge produced in the SBR system was dewatered in a belt filter press and hauled away, along with the waste sludge (float) generated in the DAF. The activated sludge system was at full capacity, and combined with the high operating costs associated with the DAF and aerobic treatment, the confectionery company hastened its decision to begin pretreating its raw wastewater anaerobically.
Solution
ADI Systems was selected for the pretreatment project and constructed a 1.2 MG (~4540 m3) ADI-BVF® reactor. This Type S reactor treats wastewater having design chemical oxygen demand (COD), total suspended solids (TSS), and fat, oil, grease (FOG) concentrations of 9,920 mg/l, 1,650 mg/l, and 600 mg/l, respectively.
The pretreated effluent flows from the reactor to the existing SBR system for polishing. The BVF® reactor is constructed in an above-ground bolted-steel tank that is insulated and covered with a floating membrane cover system. The biogas produced is collected and flared.
Results
Due to the BVF reactor’s ability to remove the bulk of the organic loading, SBR capacity was reduced to a single reactor. As a result, a significant portion of the electrical energy usage was eliminated and the volume of waste aerobic sludge was greatly reduced, producing an attractive savings for the manufacturer.
The BVF reactor is very adept at handling high inputs of TSS and FOG and produces a high-quality effluent without the need for preliminary pretreatment. The reactor consistently achieves greater than 90% biochemical oxygen demand (BOD) removal and over 85% COD removal.
