While all sectors of the food processing industry, ranging from fruit and vegetables to meat, poultry, seafood and dairy, generate a large amount of wastewater, the beer brewing industry stands out for its high strength and oftentimes high volume of wastewater. The presence of craft breweries continues to climb and breweries must contend with high BOD wastewater in order to comply with a combination of federal, state and local limits. Municipalities can charge the breweries for discharging wastewater that exceeds TSS, Temperature, pH, and/or BOD limits. A wastewater treatment strategy can have a big impact by reducing costs and liability.
The sources of wastewater at breweries range from activities such as washing spent grain wash, which results in very high suspended solids (approximately 30,000 ppm TSS) and rinsing yeast for fermenting, which results in suspended solids of approximately 6,000 ppm and BOD up to 100,000 ppm. The two types of BOD that must be considered are insoluble and soluble. The insoluble type is total suspended solids (TSS), while soluble sugars and alcohols are dissolved in the wastewater. For solids removal, there are physical screening, separation and filtration treatment methods. Solids removal options include settling, screening or filtering with or without chemical addition. However, while solids removal may achieve 30 to 50-% of total BOD, this method does not remove soluble BOD. A growing number of craft brewers have found that aerobic digestion and bioreactors can reliably and cost-effectively minimize total wastewater volume and reduce discharge loads by rapidly treating high BOD wastewater streams. One such craft brewer is Revolver Brewing is located thirty-five minutes southwest of Fort Worth in historic Granbury, Texas. Revolver brews world-class beer in the Texas countryside starting with fresh water from the Trinity Aquifer well.
The screw press application at Revolver Brewing is as follows:
|Feed Stock||Hops tank bottoms sedimentation from beer vats|
|Feed Total Solids||2-3%|
|Solids Capture Rate||98%|
The slurry is aerobically digested material utilizing high speed aerators from cement pond. Solids are decanted to a feed holding tank and then feed to the screw press. The Screw Press discharge water is returned to the city.
The design of the DRYCAKE Screw Press facilitates installations to be either inside buildings or outside without any sheltering, allowing direct disposal of thickened or dewatered sludge to a container or holding tank.