Effect of Ni and Co as Trace Metals on Digestion Performance and Biogas Produced from The Fermentation of Palm Oil Mill Effluent

Abstract

Macro and micro nutrients are important ingredients for successful anaerobic digestion. The presence or lack of nutrients can enhance or limit the functioning of the fermentation process. Micro-nutrients most often reported as stimulatory are trace metals such as nickel, cobalt, iron, and zinc. The purpose of this research is to study the effect of nickel and cobalt as trace metals on digestion performance and biogas produced from the fermentation of palm oil mill effluent (POME). Anaerobic digestion was performed in a two litres stirred tank reactor and operated at a thermophilic temperature (55 oC). As raw material, a real liquid waste (POME) from palm oil mill was used. Fresh POME was obtained from a fat pit of palm oil mill’s waste water treatment facility belongs to one of the palm oil company in North Sumatera which has VS concentration of 26,300 mg/L and COD value of 42,000 mg/L. To gain precise results, complete recording and reliable equipment of digester were employed. Supporting materials were also needed such as sodium bicarbonate, ammonium bicarbonate, and hydrochloric acid solution. Variables observed were included M-alkalinity, total solid (TS), volatile solid (VS), and biogas production. Hydraulic retention time (HRT) was maintained at 6 days. Experimental results concluded that the reduction of trace metals concentration did not affect the TS and VS concentration and M-alkalinity.