Dealing as it does with products ultimately destined for human consumption, it’s tempting to assume that the food and beverage industry has little need for biological wastewater treatment compared to other industries. Still, food and beverage waste streams frequently contain excess biological material that can pose risks to the environment and to publicly owned treatment works if they are not responsibly discharged.

One of the ways that food and beverage producers stay in compliance with discharge limits is to employ on-site biological wastewater treatment. But “what is a biological wastewater treatment system?” and “how does biological wastewater treatment work in the food and beverage industry?”

In this article, we’ll provide a simple overview of biological wastewater treatment processes and technologies and take a closer look at how they’re commonly used by food and beverage producers.

What is a biological wastewater treatment system?

The primary goal of any wastewater treatment system is to reduce the concentration of undesirable components—or contaminants—present in a liquid waste stream. Biological treatment systems achieve this objective by harnessing microbes to break down and remove contaminants from wastewater. These microorganisms work by digesting organic materials present in the waste stream. As they do so, they form new microbial biomass, either as large clumps (or “flocs”) that eventually settle out, or as fixed-surface biofilms which need no further settling.

Biological treatment systems are typically characterized by a subset of system types, which include:

• Aerobic: Aerobic treatment systems utilize microorganisms that require oxygen to function. While they are effective for streams with low to moderate contaminant levels, aerobic systems require proper management to avoid problems stemming from BOD/COD overload, improper aeration, and excess sludge buildup.
• Anaerobic: Anaerobic wastewater treatment systems utilize microorganisms that do not require oxygen. They are excellent for handling concentrated waste streams, but because they are sensitive to oxygen exposure, pH, temperature, and variations in the waste stream, anaerobic systems also require careful planning and management to avoid problems.
• Anoxic: Anoxic treatment systems are specialized for removal of nitrogen and other materials from wastewater, leveraging microbes that can use oxidized inorganic compounds in place of oxygen during respiration.

Depending on the needs of a particular facility, one or more types of biological treatment may be deployed in sequence to treat a waste stream. Also, because of weekly and seasonal variability, many biological treatment configurations in the food and beverage industry will include some form of primary treatment and/or equalization tanks to prevent damage to the biological treatment system, or to optimize efficiency.

How is biological wastewater treatment used in the food and beverage industry?

Waste streams resulting from food and beverage production often have moderate to high levels of organic material, as indicated by high measures of biochemical oxygen demand (BOD) and/or chemical oxygen demand (COD). Food and beverage wastewater may also contain suspended and dissolved solids, nutrients, and residues from cleaning, pesticides, solvents, and other materials. All of these can be disruptive to aquatic environments and to municipal treatment facilities and are therefore subject to National Pollutant Discharge Elimination System (NPDES) permit limitations, as well as regulatory restrictions.

The good news is that biological wastewater treatment can be quite efficient for helping food and beverage producers stay in compliance with discharge standards—and avoid costly fines. While some concerns, such as discharge compliance and space restrictions, are broadly shared, the food and beverage industry represents a diverse set of subsectors, each of which with distinct operations and waste treatment needs. To better understand how biological wastewater treatment technologies are used by food and beverage producers, we’ve outlined some key examples by subsector:

Dairy biological wastewater treatment

Dairy wastewater may result from packaging of milk and production of dairy products, including butter, cheese, and yogurt, among other examples. Dairy production is a water-intensive process that creates large volumes of wastewater, generally with significant organic content in the form of protein, fats, and carbohydrates. Dairy producers generate some of the highest BOD/COD levels comparative to other food and beverage subsectors and are therefore among the most common adopters of anaerobic wastewater treatment systems. Aerobic treatment systems are also commonly used.

While biological treatment presents benefits for many dairy production facilities, care must be taken in planning and maintaining systems to manage challenges particular to the dairy industry. Among these are variability in the waste stream’s organic loads and pH values, as well as the presence of non-dairy ingredients such as flavors, sugars and fruits used in processing, and residual solvents and cleaners.

Fruit and vegetable processing biological wastewater treatment

Fruit and vegetable processing creates wastewater through washing, sorting, peeling, pureeing, juicing, cooking, and cleaning, among other operational activities. The resulting wastewater is typically high in BOD from fruit and vegetable matter (e.g. skin, pulp, fibers), and may also contain soil particles, salts, and pesticide residues. Given the complexity of the stream, most wastewater treatment installations in place at fruit and vegetable processing plants include some form of pretreatment, such as dissolved air flotation or gravity separation, followed by a secondary biological treatment step. Exactly which technology is used will depend heavily upon stream contents, location, space constraints and other factors, however, commonly used technologies include aerobic and anaerobic lagoons, biological trickling filters, and activated sludge units.

Beverage biological wastewater treatment

Beverage producers generate wastewater through various aspects of operation, including cleaning and rinsing of bottles and equipment. Wastewater most typically includes sugars and other carbohydrates from beverage production, as well as residual cleaners and solvents. Increasingly, beverage producers are adopting anaerobic wastewater treatment technologies, as they not only require less energy comparative to aerobic technologies but can also produce biogas for sale or use within the facility. These cost benefits are appealing for beverage producers, who often face significant competition, and rising costs for freshwater consumption. In many cases, limited space constraints also require beverage producers to opt for compact biological treatment systems.

Meat, poultry, and seafood biological wastewater treatment

Meat, poultry, and seafood processing activities can include slaughter, butchering, trimming, washing, disinfection, freezing, transport, cooking, and packing, all of which produce wastewater. Resulting waste streams typically have high BOD/COD due to organic constituents in the form of proteins, fats, oils and greases, and are typically too concentrated and complex to be discharged to local sewers. To ensure compliance with discharge requirements, many slaughterhouses and meat packaging facilities rely on anaerobic wastewater treatment, while also seizing on the cost benefits of capturing resulting biogases.