การเพิ่มประสิทธิภาพการผลิตแก๊สชีวภาพจากน้ำเสียโรงงานสกัดน้ำมันปาล์มดิบที่ผ่านการบำบัดขั้นต้นด้วยอัลตราโซนิค

Abstract

This research aimed to enhance biogas production from crude palm oil mill wastewater. The factor that influenced on color and organic matter removal efficiency was also studied. The pretreatment methods including ultrasonication combined with natural sedimentation were investigated for palm oil mill effluent (POME) treatment, prior to the biological digestion process. The oil removal efficiencies obtained from that pretreatment method was 50.3 percent, which decreased oil content value to be in the range of recommended initial values for palm oil mill biogas operation (less than 10 g/L). The potential of an anaerobic digestion and methane gas production efficiency of pretreated POME were firstly investigated in laboratory-scale with batch digesters operated at 35 °C. The result compared with the non-pretreatment processes showed that these pretreatment processes increased methane production by 29.7 percent. The maximum methane production was 539.1 ml CH4/g COD removal from wastewater pretreated by ultrasonication. In addition, the ultrasonication can increase the reducing sugar content in wastewater 76 percent. The percent of BOD, removal increased 22.2 percent whereas about of COD removal efficiencies were increase 30.5 percent. The increasing of suspended solids and color removal efficiencies (ADMI unit) were also observed by 10.5 and 10.7 percent. For other form of organic compounds, after the anaerobic digestion process, the sonicated wastewater can increase the phenols, flavonoid, anthocyanin, lignin, and humic substances removal efficiencies by 10.5, 10.2, 14.4, 21.1, and 21.5 percent respectively in comparing with non-pretreated wastewater. After that the pretreated wastewater by different methods were studied for their biomethane production potential in semi-continuous experiments which were done in completely stirred tank reactor (CSTR) at 35 °C and 16 days of HRT. The methane yields obtained from wastewater pretreated by ultrasonication were 520.5 ml CH4/g COD removal which increased the methane production by 30.2 percent from non-pretreatment wastewater experiment. These pretreatment processes affected on the color and organics removal by would reduce the color and organics in the effluent from final pond of stabilization pond system which was the following stage after biogas system.