Biological wastewater treatment systems offer an economical means for removal of organic constituents, making them a popular choice within the food and beverage industry. Still, some aspects of food and beverage production present challenges for biological treatment, which can lead to unpredictability, inefficiency, and even damage to wastewater treatment systems if left unresolved.
So, “what are some common problems with biological wastewater treatment systems in the food and beverage industry and how do you avoid them?”
In this article, we’ll look at biological wastewater treatment challenges specific to the food and beverage industry and explore some preventative and corrective measures to mitigate their risk and impact.
What are the main challenges for treating wastewater in the food and beverage industry?
Wastewater resulting from food and beverage production is distinct for a few reasons. It is exceptional in terms of volume, as the food and beverage industry is among the top consumers of water across all industrial sectors. Additionally, food and beverage production generate wastewater with significant organic content, as opposed to the toxic chemical contaminants commonly found in other industrial wastewater streams. But the most significant distinguishing factor for food and beverage wastewater is its variability. Seasonal changes, production increases/decreases, modifications to products and production lines, kettle wash-outs, cleaning operations, and other sporadic variations are common to food and beverage manufacturing operations, and all can cause sudden and significant changes to the volume or character of a waste stream.
Both anaerobic and aerobic biological treatment systems leverage living microorganisms to break down and remove contaminants. Since these microorganisms (collectively “biomass” or “biofilm”) require a suitable and stable environment, variability in process conditions and waste stream characteristics presents a threat to the health of the biomass. Therefore, food and beverage producers’ most common problems with biological wastewater treatment are rooted in variability, as reflected in the examples provided below. This list is not exhaustive, so for a more general review of biological wastewater treatment system issues experienced across all industries, please take a look at our article Common Problems with Biological Wastewater Treatment Systems and How to Avoid Them.
BOD and COD overloads
Biological treatment systems are designed to handle specific (or maximum) amounts of biodegradable contaminants, generally measured as biochemical oxygen demand (BOD) and/or chemical oxygen demand (COD). For the food and beverage industry, excess BOD/COD overloads typically occur with seasonal fluctuations in waste stream content, changes to production lines, or a sustained increase in overall processing volumes. Routinely exceeding BOD/COD capacity can damage the biomass, which can be time-consuming and costly to reestablish. Symptoms of BOD/COD overloads include:
- Excess sludge
- Excess odors
- Changes to dissolved oxygen (DO), ammonia, and/or pH levels
- Elevated effluent BOD/COD/TSS levels
Taking preventative steps to avoid potential BOD/COD overloads is the best strategy. If your facility experiences seasonal production variability, or is considering adding or modifying its production lines, it is worthwhile to consult with a water treatment professional to ensure that increased waste stream volumes or pollutant concentrations can be accommodated by your existing wastewater treatment system. If not, you will likely need to consider strategies to increase your treatment capacity, such as through implementing recovery and reuse technologies to reduce wastewater volumes, augmenting your existing aerobic treatment systems with additional aeration equipment, or adding an equalization step (e.g., an EQ tank, a holding pond or lagoon) to normalize your waste stream ahead of biological treatment.
Alkalinity and pH
As we’ve said, it is critical to maintain suitable and stable chemical environment for the biomass colony to perform at peak capacity. Most biological treatment systems should be sustained at a neutral to slightly alkaline pH range (e.g., pH 6.5-8.5) in order to promote optimal function. 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.
Biological wastewater treatment systems, therefore, require careful monitoring and management of pH levels. Often in the course of treatment, the biomass can produce acids, and plant operators will generally need to ensure that sufficient alkalinity is present in the waste stream in order to maintain proper pH. This balance can be upset by sudden increases in levels of organic materials in the waste stream, which can cause excess activity in the biomass, resulting in drops in pH levels and eventual damage to the biomass. In these cases, excess acidity can often be managed by controlled addition of alkaline solutions, such as magnesium hydroxide, potash, or caustic soda.
Excess alkalinity, on the other hand, can arise in wastewater streams with ammonia constituents, such as those with significant animal waste content generated by meat and poultry production. High pH levels greater than 8.5 can be toxic to the microorganisms used in biological treatment systems, and can quickly kill off the biomass. This is a particular risk for anaerobic wastewater treatment systems, whose biomass can take weeks or months to reestablish. Reduction of high pH levels can be accomplished by adding phosphoric acid, hydrochloric acid, or carbon dioxide. Another approach consists of diluting the waste stream, which can sometimes be done economically by combining recycled treated effluent with the raw waste stream.
Biological wastewater treatment systems are sensitive to temperature and must be operated within the recommended temperature range, typically 59oF to 104oF for mesophilic populations. The ideal operating temperature will differ depending upon the specific microorganisms that comprise the biomass, but in general, the rate of digestion increases as temperature increases. When temperatures rise too high (e.g., above 104oF), however, the biomass can quickly deteriorate. Inappropriate temperature conditions are typically observed as elevated effluent containing BOD/COD, and/or high or low dissolved oxygen content.
Regulating temperature can be a particular problem for food & beverage producers, since many operate plants located in climates with significant seasonal temperature changes. It is sometimes necessary to invest in heating systems to ensure that biological treatment units are always operating within the optimal temperature range of approximately 70oF to 90oF. In some cases, facilities are able to economically meet their heating needs by recycling biogas produced by their anaerobic treatment process to a cogen engine or steam boiler.
Can SAMCO Help?
SAMCO has over 40 years’ experience custom-designing and manufacturing biological wastewater treatment systems, so please feel free to reach out to us with your questions.
Our biological treatment solutions—including FBBR, MBR, MBBR, and biological trickling filter solutions, among others—can help your facility:
- decrease its footprint, chemical use, and energy consumption
- produce high-quality effluent
- recycle organically contaminated water
- manage high levels of BOD and difficult-to-treat wastewaters
- control or eliminate odors
For more information or to get in touch, contact us here. You can also visit our website to set up a call with an engineer or request a quote. We can walk you through the steps for developing the proper solution and realistic cost for your biological wastewater treatment system needs.
For more information on biological wastewater treatment, see these other articles that might interest you:
- What Are the Best Biological Wastewater Treatment Equipment Supply and Technology Companies?
- How Much Do Biological Wastewater Treatment Systems Cost?
- Biological vs. Chemical Wastewater Treatment Which Is Better for Your Industrial Facility?
- What Is a Biological Wastewater Treatment System and How Does It Work?