Frosty Goodness

March 5, 2013
Microbrewery receives enhanced secondary treatment for substantially greater capacity

About the author: Steve Woodard is senior technology manager for Siemens Water Technologies. Woodard can be reached at [email protected] or 207.221.8223.

Founded in 1989, the Long Trail Brewing Co., one of the top 25 craft breweries in the nation and a local attraction, quickly outgrew the capacity of its basement location at a woolen mill in the town of Bridgewater, situated in Vermont’s Green Mountains. In 1995, the brewery relocated to a larger facility nearby with a wastewater treatment plant designed to treat high-strength wastewater with a BOD5 concentration of approximately 10,000 mg/L. 

Continued success resulted in increased production volume and the need for a solution that could handle a significant spike in high-strength brewery waste. It also had to be cost-effective and meet the confines of the brewery’s limited footprint. In addition, the Long Trail Brewing Co. wanted to find a way to enhance nitrification and denitrification to protect the environment by providing a higher level of nitrogen removal and overall treatment plant stability.  

A Cost-Effective & Sustainable Process

An upgrade to the existing activated sludge system using membrane bioreactors or high-rate anaerobic treatment technology initially was considered. Ultimately, the BioMag system from Siemens was chosen.  

The brewery selected the system because it would be able to cost-effectively increase the wastewater treatment facility’s capacity, without the need to increase tankage or physical footprint.

System Overview

Simple to integrate, operate and maintain, the BioMag system uses magnetite to ballast biological floc, enhance treatment capacity and improve performance without adding capital-intensive new tankage or energy-intensive operating costs. With a specific gravity of 5.2 and a strong affinity for biological solids, magnetite substantially increases the settling rate of biological floc, providing reliable control over the depth of secondary sludge blankets, as well as increases in mixed-liquor suspended solids (MLSS) concentration. Higher MLSS concentration enables the treatment of increased hydraulic flows or surges and loadings, all within existing tankage.

The system uses the following process:

  • Magnetite is added to the biological reactor and enmeshed into the floc.
  • The aeration system keeps the ballasted floc suspended, with MLSS increasing to 10,000 mg/L.
  • Effluent from the reactor is sent to the secondary clarifier, with the biological floc quickly settling and separated from the secondary effluent.
  • The magnetite is separated from the waste-activated sludge (WAS) and recycled to the biological process, with the remaining WAS sent to sludge processing. 
  • The magnetite is recovered and recycled.
  • The system can be applied to both new and existing treatment plants and reduces footprint and tankage while improving treatment.

Advantages of the system include:

  • Enhanced solids separation within the existing facility, thereby increasing treatment capacity;
  • Low capital and O&M costs;
  • Ability to meet regulatory requirements in the long term;
  • Reliable and proven components;
  • Simplicity of operation; and
  • Environmentally sound investment.

One Compact System 

With the new system, the Long Trail Brewing Co. generated additional savings by enabling the company to process heavy yeast concentrations produced by brewing on site instead of transporting them off site for disposal.

Although the average daily effluent discharge has increased steadily since 2006, the monthly average BOD5 and total suspended solids in the effluent have decreased.

The installation team also helped facilitate full nitrification/denitrification, including upgrading their existing anoxic zones, adding a post-anoxic zone and adding more aeration capacity. 

“The BioMag system produced results that enabled the brewery to produce a higher volume of product with an increased treatment capacity, while not increasing its physical or ecological footprint,” said Brandon Mayes, assistant quality assurance manager for Long Trail Brewing Co.

The brewery experienced the following results with the new treatment system:

  • It doubled existing flow and organic loading capacity.
  • The clarifier solids loading rate more than doubled capacity.
  • Water treatment capacity increased from 500 lb per day to 1,300 lb per day BOD. 
  • Full nitrification and denitrification were achieved.
  • The footprint of the plant was not increased.
  • Significant capital savings were achieved compared with alternatives considered.

As a winner of the Vermont Governor’s Award for Environmental Excellence, the Long Trail Brewing Co. ranks eco-friendly and sustainable practices as a high priority. The BioMag system exceeded the company’s expectations as an efficient solution for enhanced capacity and superior nutrient removal, as well as a sustainable process for lower operational expenses.

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About the Author

Steve Woodard

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