Introducing a new GHG emission calculation approach for alternative methane reduction measures in the wastewater treatment of a palm oil mill

Palm oil mill wastewater treatment is a significant source of greenhouse gas (GHG) emissions. The wastewater, palm oil mill effluent (POME), carries substantial amounts of organic matter: If left in ponds, most of this organic matter would decompose relatively quickly into methane (CH4) and carbon dioxide. A belt filter press has been introduced as a means to separate organic matter from the wastewater. Solidified organic matter, the belt press cake recovered with a belt filter press, can be further used as organic fertilizer in the plantation. The aim of this study was to confirm that there is a reduction of CH4 emissions associated with the belt filter press and to find a simple method for determining the reduction at the palm oil mills. CH4 measurements and total organic carbon (TOC) analysis were conducted in a palm oil mill in Malaysia. The emissions were measured both in ponds with solid separation and in baseline open ponds without any CH4 reduction measures. TOC was measured in POME and in belt press cake. By removing organic matter, the measured palm oil mill CH4 emissions of the POME ponds were reduced by 11%. The reduction was as high as 54% in the single pond where the belt filter press was installed. A calculative 13% reduction in methane formation potential was confirmed with TOC measurement. TOC measurement was found to be a simple method worth considering for determining GHG reduction.