Palm oil is a cornerstone of the global edible oil industry, supplying over 77 million metric tons annually to food, cosmetic, and biofuel markets. While palm oil milling is an efficient process in terms of oil yield per hectare, it inevitably generates substantial amounts of waste. If these waste streams are not properly managed, they can pollute the air, contaminate the water, and consume too much land. However, a large portion of this garbage may be cleaned up, recycled, or turned into useful byproducts thanks to contemporary technologies and environmentally friendly methods.

Waste Generation in Palm Oil Milling

Palm oil is extracted from the mesocarp (flesh) of fresh fruit bunches (FFBs). After sterilization, threshing, digestion, pressing, and clarification, crude palm oil (CPO) is separated from the solids and liquids. The remaining residues are considered waste but can be processed or repurposed.

Main Waste Types:

Waste Type	Source	Physical Form
Empty Fruit Bunches (EFB)	After threshing	Solid biomass
Palm Press Fiber	After pressing	Moist fiber
Palm Kernel Shells (PKS)	Kernel processing	Hard shell
Palm Oil Mill Effluent (POME)	Oil clarification	Liquid/slurry
Boiler Ash & Fly Ash	Biomass combustion	Fine solid waste
Sterilizer Condensate	From steam sterilization	Liquid

A 60-ton-per-hour (TPH) palm oil mill can generate more than 200 tons of solid waste and 600–800 m³ of POME daily.

Solid Waste: Types and Management Strategies

Empty Fruit Bunches (EFB)

Generation Rate:

• ~22% of FFB weight
• For 60 TPH mill: ~300 tons/day

Environmental Issue:

If left untreated, EFB can decay, release methane, and attract pests.

Management Solutions:

Mulching and Composting:

• EFB is shredded and applied back to plantations to retain moisture and reduce erosion.
• Composting with POME can enhance nutrient value.

Boiler Fuel (After Drying):

• • Some mills dry EFB to <40% moisture and co-fire it with shells/fibers in boilers.
  • Heat value: ~7.2 MJ/kg (lower than shells)

Biochar and Pelletization:

• EFB can be carbonized to biochar for soil conditioning.
• Pelletized EFB is used in biomass power plants.

Palm Press Fiber

Generation Rate:

• ~13–15% of FFB weight
• Contains residual oil and moisture

Management Solutions:

Boiler Fuel:

• Commonly used as biomass fuel in mill boilers.
• Heat value: ~14–17 MJ/kg

Composting:

Mixed with EFB and POME to produce organic fertilizer.

Oil Recovery:

Fiber-oil recovery presses or solvent extraction systems can recover up to 1.5–2% of residual oil.

Palm Kernel Shells (PKS)

Generation Rate:

~5–7% of FFB weight

Management Solutions:

Boiler Fuel:

High calorific value (~18–20 MJ/kg), commonly used in steam generation.

Commercial Sale:

Exported for biomass energy and activated carbon production.

Carbonization:

Used to make biochar and charcoal briquettes.

Boiler Ash and Fly Ash

Generation Rate:

~1–3 tons/day for 60 TPH mill

Management Solutions:

Soil Amendment:

Rich in potassium and calcium, applied in controlled amounts to palm fields.

Cement Manufacturing (Experimental):

Potential use as a pozzolanic material in blended cement.

Liquid Waste: Palm Oil Mill Effluent (POME)

What is POME?

Palm Oil Mill Effluent (POME) is a brownish slurry composed of sterilizer condensate, decanter effluent, and clarifier sludge. It contains high levels of:

• Biological Oxygen Demand (BOD): ~25,000 mg/L
• Chemical Oxygen Demand (COD): ~50,000 mg/L
• Suspended Solids: ~18,000 mg/L
• Oil & Grease: ~4,000 mg/L

For comparison, untreated municipal sewage has a BOD of 300–400 mg/L, making POME over 60x more polluting.

How Is POME Managed?

Anaerobic Ponding System

• Most widely used system
• Involves 4–6 open ponds where microbes break down organic matter without oxygen
• Retention time: 60–90 days
• Methane gas (CH₄) is produced and can be flared or captured

Pros: Low-cost, easy to operate

Cons: Large land requirement, odor, potential for overflow in the rainy season

Biogas Recovery Systems

Modern mills use covered anaerobic digesters to capture methane from POME.

• Gas Yield: ~28 m³ of methane per ton of FFB
• Energy Potential: 5–6 MWh/day for a 60 TPH mill

Usage:

• Power for mill operations
• Grid export (in some countries)
• Carbon credit generation (under CDM/VER schemes)

Advanced Wastewater Treatment

For discharge into waterways or irrigation, POME must be polished to meet discharge standards:

Parameter	Standard Limit (Malaysia DOE)
BOD	<100 mg/L
COD	<500 mg/L
Suspended Solids	<400 mg/L
pH	5–9

Technologies used:

• Aerobic treatment
• Membrane bioreactors
• Sludge dewatering and drying beds

Air Emissions: Smoke, Steam, and Odors

Smoke from Biomass Boilers

Inefficient biomass combustion releases particulate matter, CO, and NOx into the air. Some mills still use old-style chimneys or open burning (which is discouraged or banned).

Control Methods:

• Cyclone and Wet Scrubbers
• Electrostatic Precipitators (ESP)
• Upgraded combustion systems

Steam and Odor from Sterilizers

Open sterilizer exhaust vents to release steam and odor from decaying fruit. This can affect local air quality.

Mitigation:

• Closed sterilization systems
• Condensate capture
• Odor filters or activated carbon traps

By-Product Utilization and Circular Economy

Mills’ practice of zero waste strategies aims to convert all waste streams into usable products.

Examples:

Waste Stream	Converted Product	Market Use
EFB + POME	Compost / Organic Fertilizer	Plantation nutrient cycling
POME	Biogas	Energy, carbon credits
Fiber	Oil recovery + Boiler Fuel	Energy and revenue
Ash	Soil conditioner	Plantation management
PK Shells	Export biomass, activated carbon	Industrial fuel, filtration

Regulatory Requirements and Certifications

National Regulations

Countries like Malaysia, Indonesia, Nigeria, and Colombia enforce effluent discharge and air pollution standards for palm oil mills.

Non-compliance can lead to:

• Fines
• Shutdown orders
• Denial of export licenses

Sustainability Certifications

Organizations like RSPO (Roundtable on Sustainable Palm Oil) and ISCC (International Sustainability & Carbon Certification) require documented waste management systems.

Certification Requirements:

• Documented waste tracking and reuse
• No discharge into rivers or protected areas
• Safe handling and storage of all residues

Future Trends in Palm Oil Waste Management

With rising environmental concerns and global sustainability goals, palm oil mills are evolving from waste-generating operations to eco-industrial hubs.

Key Innovations:

• Closed-loop water systems (zero liquid discharge)
• Integrated biomass gasification
• Black soldier fly composting of sludge
• Palm oil mill–refinery integration

Palm oil mills produce significant waste, but with proper infrastructure and technology, much of it can be reused or monetized. EFBs, POME, fibers, and shells offer opportunities for renewable energy, fertilizers, and biomass products. As sustainability standards tighten, effective waste management becomes essential for cost savings, new revenue, and long-term competitiveness.