Co-composting of palm oil mill waste and waste water - a powerful process to reduce green house gas emissions

In palm oil mills the residues from the production process, dumped Empty Fruit Bunches (EFB) and stored Palm Oil Mill Effluent (POME) in anaerobic ponds, are responsible for emissions of green house gases (methane and laughing gas). Co-composting of EFB and POME in open windrows is the only alternative to treat both in a sustainable way. In a life cycle assessment (LCA) the Global Warming Potential (GWP) of conventional EFB and POME treatment and of co-composting, with and without biogas production from POME, was determined. The GWP of palm oil mill waste treatment can be reduced from 245 kg CO2eq per t FFB (worst case: POME in anaerobic ponds, dumping of EFB) up to 6 kg CO2eq per t FFB (co-composting of EFB and POME, biogas from POME at CH4 losses<2%) due to reduced methane emissions and nutrient recycling. Co-composting of EFB and POME is a profitable way to use the nutrients from both POME and EFB.