Abstract:
This research aimed to compare biogas production of pretreatment method using electrocoagulation processes for palm oil mill wastewater. The efficiency of anaerobic digestion was conducted by BMP method. The experiments were operated in batch processes using direct current power supply with varying current density at 0.02, 0.05 and 0.1 A/cm² and using the retention time of 5, 10 and 15 minutes, respectively. Iron was used as an electrode material with separating distance of 2.5 cm and surface area of 65 cm². The electrodes were submerged in wastewater 400 ml and contained in 600 ml beaker. The experiments showed that current density at 0.05 A/cm² for 5 minutes could enhance soluble COD the most. The soluble COD produced was 31,157 mg/L and FOG removal was 94.00±0.17%. The current density at 0.1 A/cm² for 5 minutes could produce soluble COD at 22,494.67±105 mg/L and FOG removal 98.42±0.42%. This was because high current density cause high temperature which could breakdown oil into soluble oil and could complete oil removal by through hydrogen gas flotation. This cause reduction in high molecular weight oil that bacteria in anaerobic digestion could not digest in short time and also could enhance cumulative biogas production in 30 days. At current density 0.05A/cm² for 5 minutes, we could get cumulative biogas production in 30 days at 24.02 ml/g VS and had methane gas 74.35%. For 0.1A/cm², we could get cumulative biogas production in 30 days to be 23.31 ml/g VS and had methane gas at 20.10%. In terms of palm oil mill wastewater without electrocoagulation pretreatment, we got the cumulative biogas production and methane gas of less than palm oil mill with pretreatment by electrocoagulation. The biogas obtained was 11.33 ml/g VS and methane gas at 59.59 %