Dairy Wastewater Treatment Case Study: 81% BOD Reduction in 20 Days
Overview
- 81% reduction in average BOD concentration within 20 days
- Average BOD reduced from approximately 98 mg/L to 19 mg/L
- BOD reduced below the required 25 mg/L discharge limit in all four lagoon cells
- 94% reduction in fecal coliform within 20 days
- Initial Bio React treatment followed by an ongoing Aqua Assist maintenance program
- Dairy processing wastewater lagoon serving a major Canadian cheese producer
The Challenge: Meeting BOD Discharge Requirements
A major cheese producer in Canada was struggling with elevated BOD concentrations in the effluent from its wastewater lagoon system. The treatment system consisted of four lagoon cells with an average BOD concentration of approximately 98 mg/L. To meet discharge requirements, the facility needed to reduce BOD to below 25 mg/L before the treated wastewater could be discharged. With BOD concentrations nearly four times the required discharge limit, the facility needed to rapidly improve biological treatment performance across all four lagoon cells.
The objective was clear: reduce BOD below the required discharge limit and restore the lagoon system to acceptable discharge conditions.
The Initial Bio React Treatment
To address the elevated BOD concentrations, Drylet recommended an initial Bio React treatment across all four wastewater lagoon cells. Each lagoon was treated with Bio React at a rate of 50 pounds per million gallons of lagoon capacity. The objective of the initial treatment was to support biological activity within the lagoon system and accelerate the breakdown of biodegradable organic material contributing to the elevated BOD.
Following application, the facility continued monitoring BOD and fecal coliform concentrations to evaluate the response across the four lagoon cells. This initial treatment was designed to address the immediate wastewater performance challenge before transitioning the facility to an ongoing biological maintenance program.
Results After 20 Days
Within 20 days of the initial Bio React treatment, the cheese producer documented substantial improvements across the wastewater lagoon system. Average BOD concentration declined from approximately 98 mg/L to 19 mg/L, representing an 81% reduction.
More importantly for the facility, BOD concentrations were reduced to below the required 25 mg/L discharge limit in all four lagoon cells. This allowed the facility to meet its BOD discharge requirement. Fecal coliform concentrations also declined by 94% during the same 20 day period.
Key Results
- 81% reduction in average BOD concentration
- Average BOD reduced from approximately 98 mg/L to 19 mg/L
- All four lagoon cells reduced below the 25 mg/L BOD discharge limit
- 94% reduction in fecal coliform concentration
- Results documented within 20 days of the initial treatment
Transition to Ongoing Aqua Assist Treatment
After achieving the required BOD reduction, the facility transitioned from the initial Bio React treatment to an ongoing Aqua Assist treatment program. The cheese producer began adding 1 pound of Aqua Assist to the wastewater influent each day as part of its routine treatment protocol.
The ongoing program was designed to support biological treatment as new dairy processing wastewater continuously entered the lagoon system. Rather than waiting for BOD concentrations to rise again before taking corrective action, the facility incorporated biological treatment into its regular wastewater management strategy. This approach provided a practical transition from addressing an immediate discharge challenge to supporting ongoing lagoon treatment performance.
Why BOD Reduction Matters in Dairy Processing Wastewater
Dairy processing wastewater can contain high concentrations of biodegradable organic material from milk solids, fats, proteins, sugars, and other production residues. These organic compounds contribute to BOD and can place significant demand on biological wastewater treatment systems. High BOD concentrations indicate that microorganisms require more oxygen to break down the organic material present in the wastewater. If the biological treatment process cannot keep pace with the incoming organic load, effluent BOD can remain elevated and create discharge compliance challenges.
For this cheese producer, reducing average BOD from approximately 98 mg/L to 19 mg/L brought the lagoon system below the required discharge limit and demonstrated a substantial improvement in treatment performance. Maintaining effective biological activity is especially important in food and dairy processing wastewater systems because organic loading can vary with production schedules, cleaning cycles, and changes in processing operations.
Understanding the Fecal Coliform Reduction
In addition to the reduction in BOD, the facility reported a 94% decrease in fecal coliform concentration within 20 days. Fecal coliform is commonly monitored as an indicator of microbial water quality. Elevated concentrations can affect discharge requirements depending on the facility's permit and receiving environment.
The fecal coliform reduction occurred during the same period in which BOD concentrations declined across the lagoon system. However, biological treatment should not be characterized as a replacement for required disinfection processes. For this facility, the documented reduction represented an additional improvement in wastewater quality during the 20 day treatment period.
Operational Significance for Dairy Processors
Dairy processing wastewater can place substantial and variable organic loads on biological treatment systems. When treatment performance falls behind those loads, facilities may face elevated effluent BOD and increased compliance pressure. This case demonstrates the value of addressing both immediate treatment performance and ongoing biological stability. The initial Bio React treatment reduced average BOD by 81% within 20 days, bringing all four lagoon cells below the facility's required discharge limit.
The subsequent Aqua Assist program provided an ongoing biological treatment strategy as new wastewater continued entering the system.
For dairy and food processing facilities, the case highlights several important considerations:
- Monitor BOD trends before concentrations create discharge problems
- Evaluate organic loading when biological performance begins to decline
- Support biological treatment as wastewater characteristics and production loads change
- Use measured wastewater data to evaluate treatment response
- Incorporate ongoing biological management rather than relying only on corrective treatment after performance declines
When Food and Dairy Processors Should Evaluate Biological Treatment
Food and dairy processing facilities may benefit from evaluating biological treatment performance when wastewater conditions begin changing or when existing treatment processes struggle to manage organic loading.
Conditions that may warrant further evaluation include:
- Increasing effluent BOD concentrations
- Difficulty consistently meeting discharge requirements
- Changes in wastewater strength or organic loading
- Treatment performance that varies with production schedules
- Increased loading from cleaning or processing operations
- Biological treatment that struggles to recover after high load events
- Recurring wastewater performance problems that require corrective treatment
These conditions can have multiple causes. Wastewater characteristics, dissolved oxygen, temperature, pH, nutrient availability, retention time, microbial activity, and treatment system design can all influence biological performance. Evaluating the complete treatment process can help identify the factors contributing to elevated BOD and determine whether biological treatment adjustments are appropriate.
FAQ: Dairy Processing Wastewater Treatment
Why is BOD often high in dairy processing wastewater?
Dairy processing wastewater can contain milk solids, fats, proteins, sugars, and other biodegradable organic material. These compounds increase the oxygen demand placed on biological wastewater treatment systems and can contribute to elevated effluent BOD when treatment capacity does not keep pace with organic loading.
Can biological treatment reduce BOD in dairy wastewater?
Biological treatment uses microbial activity to break down biodegradable organic material that contributes to BOD. In this case, average BOD declined from approximately 98 mg/L to 19 mg/L within 20 days, an 81% reduction.
Why is ongoing biological treatment important after BOD improves?
Dairy processing facilities continuously generate wastewater, so new organic material continues entering the treatment system. Ongoing biological treatment can help support treatment performance as wastewater strength, production schedules, and organic loading change over time.
Does biological treatment replace wastewater disinfection?
No. Biological treatment should not be considered a replacement for required disinfection. Although this facility reported a 94% reduction in fecal coliform during the 20 day treatment period, disinfection requirements depend on the facility's permit and treatment process.
Evaluate Your Wastewater Treatment Performance
If your food or dairy processing facility is experiencing elevated BOD, changing organic loads, or difficulty maintaining consistent treatment performance, Drylet can evaluate your existing wastewater system and identify opportunities to improve biological treatment.
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