Food Factory Wastewater Malaysia: Common Causes of High COD, BOD and Oil & Grease

Why Is Food Factory Wastewater in Malaysia Difficult to Treat?

Food factory wastewater typically contains high concentrations of organic matter, suspended solids, fats, oils, and grease (FOG). Ingredients such as sugars, starches, proteins, dairy products, edible oils, and food residues contribute to elevated Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD), making biological treatment more challenging if the wastewater is not properly equalised and pre-treated.



Maintaining stable wastewater treatment requires understanding the source of these pollutants rather than simply increasing chemical dosage or aeration.

Why Food Processing Wastewater Is Different

Three Important Food Factory Wastewater Parameters

Chemical Oxygen Demand (COD)

What Is COD?

COD measures the total amount of oxygen required to chemically oxidise organic pollutants.

High COD usually indicates a large amount of dissolved organic matter entering the treatment system.

Common Sources of High COD

Operational Impact

High COD increases oxygen demand within the biological treatment process.

If the loading exceeds the design capacity, operators may observe:

• Low dissolved oxygen
• Reduced treatment efficiency
• Rising sludge production
• Higher operating costs 

Biochemical Oxygen Demand (BOD)

What Is BOD?

BOD measures biodegradable organic pollutants that microorganisms consume during biological treatment.

Common Sources

Operational Impact

High BOD increases biological activity but may also:

• Overload aeration systems
• Cause sludge bulking
• Increase foam formation
• Reduce nitrification performance
  

Oil & Grease

Why Oil & Grease Matter

Oil and grease are among the most common wastewater treatment challenges in food processing.

Typical sources include:

Operational Impact

Excessive FOG can:

• Coat biological flocs
• Reduce oxygen transfer
• Block pipelines
• Increase sludge production
• Cause odour problems
• Reduce clarifier performance

Many food factories therefore install Dissolved Air Flotation (DAF) systems to remove oil and grease before biological treatment.

Common Wastewater Characteristics by Food Industry

Why Food Factory Wastewater Changes Every Day

Many factories assume wastewater quality remains relatively constant.

In reality, wastewater characteristics vary due to:

• Different production batches
• Seasonal demand
• Product changeovers
• Cleaning schedules
• Raw material changes
• Production downtime
• Maintenance activities

These fluctuations are one of the main reasons equalisation tanks (EQ Tanks) are critical in food industry wastewater treatment.

How Food Factories Can Reduce High COD and BOD

Instead of relying solely on wastewater treatment, many factories first reduce pollution at the source.

Examples include:

• Recovering product spills before washing
• Improving housekeeping
• Segregating high-strength waste streams
• Optimising CIP procedures
• Reducing water consumption
• Installing effective equalisation
• Optimising DAF performance
• Maintaining healthy biological treatment

Reducing pollutant loading before treatment often lowers chemical consumption and improves overall treatment stability.

Recommended Treatment Technologies

The best treatment process depends on wastewater characteristics rather than industry alone.

Engineering Insight

One observation across food manufacturing facilities is that wastewater treatment performance is often limited by influent variability rather than treatment technology.

Plants with effective equalisation, proper DAF operation, and stable biological treatment generally experience fewer compliance issues than facilities that attempt to compensate for poor influent control by increasing chemical dosage.

This reinforces an important principle:

Stable influent produces stable effluent.

Final Thoughts on Food Factory Wastewater in Malaysia

Food factory wastewater presents unique treatment challenges because pollutant concentrations and hydraulic loading can vary significantly throughout the day.

Understanding where COD, BOD, and oil & grease originate allows manufacturers to improve process control, reduce treatment costs, and achieve more stable environmental compliance.



Rather than relying on corrective actions after problems occur, successful facilities focus on source reduction, proper pre-treatment, biological stability, and continuous optimisation.

Looking to Optimise Your Food Factory Wastewater Treatment System?

Frequently Asked Questions

Why is COD so high in food factory wastewater?

COD is primarily caused by dissolved organic materials such as sugars, starches, proteins, fats, and food residues generated during manufacturing and cleaning operations.

Is high BOD always a problem?

Not necessarily. BOD represents biodegradable organic matter that biological treatment can remove. Problems occur when loading exceeds the treatment plant's design capacity or operational control is poor.

Why is oil and grease difficult to treat?

Oil and grease reduce oxygen transfer, interfere with biological treatment, and can cause blockages and sludge settling problems. Effective pre-treatment, such as Dissolved Air Flotation (DAF), is often required.

Which wastewater treatment system is best for food factories?

There is no universal solution. Technology selection depends on wastewater characteristics, discharge requirements, available space, operating costs, and long-term operational objectives.

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