The Client's Needs
Valley Pride Pack wanted to reduce the operational costs associated with their wastewater treatment system. A search for a cost-effective and reliable process was conducted by the plant’s head treatment operator. In addition to reducing operating costs, the new treatment system had to be capable of treating an average hydraulic flow of 643 m³/d with surges up to 1,060 m³/d.
The existing plant consisted of a chemical pretreatment system ahead of an anaerobic selector and an aerobic activated sludge process. The pretreatment system was costly with high chemical and sludge disposal costs. The entire wastewater treatment plant was not capable of meeting the effluent permit limits imposed on the facility when it treated 100% of the plant wastewater, therefore a portion of the wastewater flow had to be hauled to publicly owned treatment works. In fact only about 20,000 gal/d (75 m3/d) was able to be discharged with typically more than 800,000 gal/month being hauled to the POTW’s. With 100% of it’s land application space being used and treatment and hauling costs mounting, the industry needed a good solution.
Valley Pride Pack opted for a two-stage AnoxKaldnes™ Moving Bed biofilm process to replace both the chemical pretreatment system and the anaerobic system. This two stage MBBR was followed by Dissolved Air Flotation (DAF) for solids removal prior to treatment by the existing activated sludge process.
The two moving bed biofilm reactors were installed between the existing equalization (EQ) tank and the activated sludge process while utilizing the existing dissolved air flotation (DAF) unit from the old chemical pretreatment system. The MBBR reactors provided removal of the heavy COD concentrations while the DAF reduced solids ahead of the conventional AS system which could not focus on the job of nitrification.
The figure below shows the dramatic increase in flow discharged from the facility to the local creek and the decrease in flow shipped to local POTWs for treatment. Other operational advantages seen since the incorporation of the AnoxKaldnesTM moving bed biofilm system is a more stable activated sludge system. Sludge Volume Index (SVI) values prior to the biofilm reactors coming online were in the 200 range and after 2-3 months of having the MBBR™ biofilm reactors in operation, the SVI values dropped dramatically to less than 75.