Chapter 20

Wastewater and Solid Waste Management

Brewery Wastewater Treatment

Wastewater from a brewery may be discharged into either a waterway (rivers, streams, or lakes), directly into a municipal sewer system, or into the municipal sewer system after the wastewater has undergone some treatment.

Physical Treatment

Physical treatment is for removing coarse solids and other large materials, rather than dissolved pollutants. It may be a passive process, such as sedimentation to allow suspended pollutants to settle out or float to the top naturally.

Flow Equalization

Flow equalization is a technique used to consolidate wastewater effluent in holding tanks for "equalizing" before introducing wastewater into downstream brewery treatment processes or for that matter directly into the municipal sewage system.

Screening

Typically, the wastewater is first screened to remove glass, labels, and bottle caps, floating plastic items and spent grains.

Grit Removal

After the wastewater has been screened, it may flow into a grit chamber where sand, grit, and small stones settle to the bottom.

Gravity Sedimentation

With the screening completed and the grit removed, wastewater still contains dissolved organic and inorganic constituents along with suspended solids. The suspended solids consist of minute particles of matter that can be removed from the wastewater with further treatment such as sedimentation or chemical flocculation.

Chemical Treatment

Among the chemical treatment methods, pH adjustment and flocculation are some of the most commonly used at breweries in removing toxic materials and colloidal impurities.

pH Adjustment

The acidity or alkalinity of wastewater affects both wastewater treatment and the environment. Low pH indicates increasing acidity while a high pH indicates increasing alkalinity (a pH of 7 is neutral). The pH of wastewater needs to remain between 6 and 9 to protect organisms. Alkalis and acids can alter pH thus inactivating wastewater treatment processes.

Flocculation

Flocculation is the stirring or agitation of chemically-treated water to induce coagulation. Flocculation enhances sedimentation performance by increasing particle size resulting in increased settling rates.

Biological Treatment

After the brewery wastewater has undergone physical and chemical treatments, the wastewater can then undergo an additional biological treatment. Biological treatment of wastewater can be either aerobic (with air/oxygen supply) or anaerobic (without oxygen), which are discussed in more detail in the following sections. Generally, aerobic treatment has been applied for the treatment of brewery wastewater and recently anaerobic systems have become an attractive option.

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