Biological vs. Chemical Wastewater Treatment in the Food and Beverage Industry

Biological vs. chemical wastewater treatment: are both used in the food and beverage industry? And if so, how are you supposed to know which is best for your facility’s wastewater treatment needs?

In the article below, we’ll explore the different ways these two technologies are used, and discuss how, in certain instances, you might need one, the other, or even both. Although it’s difficult to say which is definitely best for your business, this article can serve as a general outline of some things you might be seeing in your food and beverage industry facility and what is typically recommended so you can have a sense of what your facility might benefit from.

As always, if you’re unsure if your facility is using the correct treatment methods for your waste, it’s always best to consult your water treatment specialists to be sure.

Chemical wastewater treatment in the food and beverage industry

There is a place for using chemicals in the food and beverage industry to clean wastewater, and this is typically when biological solutions are not applicable:

Coagulants and flocculants

For example, if your facility needed to remove particulates from its waste, biological treatment isn’t useful. In these cases, your facility will typically turn to treatment options that include chemical coagulants and flocculants that will help remove all the finer particles from the waste stream. After all the large objects are removed from the wastewater, various chemicals are added to a reaction tank to remove the bulk suspended solids and other various contaminants. This process starts off with an assortment of mixing reactors, typically one or two reactors that add specific chemicals to take out all the finer particles in the water by combining them into heavier particles that settle out. The most widely used coagulates are aluminum-based such as alum and polyaluminum chloride.

Sometimes a slight pH adjustment will help coagulate the particles, as well.

When coagulation is complete, the water enters a flocculation chamber where the coagulated particles are slowly stirred together with long-chain polymers (charged molecules that grab all the colloidal and coagulated particles and pull them together), creating visible, settleable particles that resemble snowflakes.

Controlling pH

Fluctuations in pH and alkalinity are particularly common in dairy, meat and poultry subsectors, as food and beverage producers often experience extreme pH variations in their waste streams due to seasonal or weather-related fluctuations in production, batch processing methods, changeovers, or other events. If not controlled, extreme pH levels below pH 6 or above pH 9 can quickly cause significant damage and loss of the biomass.

In the event your facility is trying to control pH, it is usually appropriate use caustic or acids. Controlling acid feed, softening, and pH/alkalinity is critical and should be closely monitored. Failure to do so can lead to rapid scale formation and/or corrosion to equipment.

Breaking down emulsions

Oils and greases are “hydrophobic,” which means they tend to repel from water and cling to surfaces free from water. High amounts of oil and grease in wastewater can clog sewer and drainage pipes in addition to harming human health and killing aquatic life, depending on the concentration and type of oil/grease. Often introduced into wastewaters as byproducts of food production, these contaminants are strictly regulated from being released with your effluent.

When these contaminants result in emulsions, chemicals can be used to break those emulsions down, in addition to other methods such as dissolved air flotation, but biological solutions aren’t typically a good fit.

Biological wastewater treatment 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). In these cases, the use of chemicals to remove contaminants doesn’t make sense. You can use them, but they’re not economically viable.

For example, in some instances you can use chemicals like hydrogen peroxide or ozone, combinations of peroxide and ultraviolet light, or hydrogen peroxide and chemical catalysts like ferrous iron to oxidize compounds in the wastewater, but you want to use biological treatment in these cases because bacteria are so much cheaper and more effective at doing it than using chemical oxidation. You might see a higher capital cost for the system, but you’ll experience much lower operating costs. We see this often when we do a lifecycle economic comparison between chemical treatment versus biological treatment. We typically see the biological option pay for itself after about 9 to 18 months. These systems also use less energy and require less manpower and resources.

Biological vs. chemical wastewater treatment systems in the food and beverage industry

There is a time when the two technologies might complement one another. Keep in mind this doesn’t happen often, but if your facility is experiencing refractile chemistry where you have soluble organics in the wastewater that are not easily biodegradable, you might be able to use chemical oxidation up front followed by a partial oxidation using hydrogen peroxide and ferrous iron or UV light. This helps break down harder-to-degrade contaminants to a point where they are biologically degradable. Then you can use a biological wastewater treatment system to treat it the bulk of the stream. You wouldn’t want to use advanced chemical oxidation to treat all of it, though. You will find this to be far too expensive. You’ll just want to use enough to convert the refractile organics to biodegradable organics, and then implement the biological treatment for the rest of the stream.

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