Overcoming wastewater treatment plant limitations by ballasting the microbial floc

Steven Woodard (1), BRANDON M. MAYES (2), William J. Yawney (2)
(1) Cambridge Water Technology, Portland, ME; (2) Long Trail Brewing Company, Bridgewater Corners, VT

The Long Trail Brewing Company’s wastewater treatment plant was designed to treat high-strength wastewater with a BOD5 concentration of approx. 10,000 mg/L. The original treatment capacity was 500 lb/day of BOD5, and the plant was limited by the performance of the secondary clarifier. As Long Trail’s future plans called for increases in production volume that would soon outgrow the brewery’s wastewater treatment capacity, a cost-effective solution that could handle the anticipated increase in high-strength brewery waste without overloading the secondary clarifier was needed. A secondary objective was to enhance nitrification and denitrification, to help protect the environment by providing a higher level of nitrogen removal and overall treatment plant stability. Long Trail considered upgrading its existing activated sludge system using membrane bioreactors (MBRs) or high-rate anaerobic treatment technology. The BioMag process was ultimately selected for its cost-effective capability to increase the capacity of the wastewater treatment facility without adding any tankage or expanding the plant’s physical footprint. BioMag is a relatively new process that enhances biological treatment systems by using magnetite to ballast, or weigh down, the biological floc. With a specific gravity of 5.2 and a strong affinity for biological solids, magnetite substantially increases the settling rate of the biomass, thereby overcoming the bottleneck in the secondary clarifier. Increasing settling rates of the biological floc provides the opportunity to increase mixed liquor suspended solids (MLSS) concentrations and treat increased hydraulic flows and loadings. The paper discusses the design, implementation, and results of the treatment plant upgrade, including adding the BioMag process and upgrading the nitrogen removal processes.

Brandon M. Mayes received a B.S. degree in biological sciences from York College of Pennsylvania. He began working for Long Trail Brewing Company in Bridgewater Corners, VT, in 2006 as the assistant quality assurance manager. Brandon is a licensed wastewater and public water systems operator with the state of Vermont. Long Trail Brewing Company is a regional brewery producing approx. 80,000 bbl of beer annually and operates an activated sludge wastewater treatment facility to treat its high-strength brewery waste.

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