Mill operators need to monitor and manage the environmental impacts of their operations in order to meet the standards required for certification.
- Sources of greenhouse gas (GHG) emissions include the transportation of staff and fresh fruit bunches (FFBs) to the mill and the diesel generators used to power the mill.
- Milling processes also require large amounts of water, and surrounding communities and ecosystems can be negatively impacted by overuse and contamination of water resources.
- The most environmentally damaging by-product of the milling process is palm oil mill effluent (POME), which is a hot, acidic effluent that contains oil, plant debris, and nutrients. Large palm oil mills typically produce an average of 0.65 tonnes of raw POME for every tonne of FFBs processed.
What are the environmental impacts of POME?
- POME has high acidity, temperature, biological oxygen demand (BOD), and chemical oxygen demand (COD). When it is discharged into waterways it can contaminate drinking water for human and animal communities. It can be particularly harmful to aquatic communities by creating highly acidic environments or causing eutrophication (where excessive algal growth occurs on the surface of the water).
- POME is typically released into open-air holding ponds for remediation, thereby releasing carbon dioxide, methane, and hydrogen sulphide, all of which contribute to global climate change.
What are the opportunities for reform?
Many new technologies are being developed to generate energy from POME and reduce associated greenhouse gas emissions and other pollution. These include biological sequencing batch reactors, biofiltration systems, high aeration rate systems, decanters, activated sludge plants with aerobic reactors, bioflow polishing plants, and membrane bioreactors. The case study developed by Musim Mas outlines how POME can be processed through an anaerobic generator to capture biogases for electricity generation. In addition to savings on electricity, methane capture enables mills to generate revenue from verified GHG reductions via the Clean Development Mechanism or other environmental financial mechanisms.
The processed POME anaerobic sludge can be added to enrich compost (sometimes made with empty FFBs) with high amounts of plant nutrients and microbes, as is alluded to in the study Oil palm composted biomass: A review of the preparation, utilization, handling and storage.