UTILIZATION OF PALM OIL MILL EFFLUENT AS A SUBSTRATE FOR ETHANOL AND HYDROGEN PRODUCTION BY ANAEROBIC PROCESSES

• Main Author: Gumilar, Andri
• Format: Dissertations
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/75158
• Institution: Institut Teknologi Bandung

Ethanol and hydrogen are promising alternatives to be used as energy sources in thefuture. Several studies related to theformation ofethanol and hydrogen through the process ofconverting organic liquid waste anaerobically have been carried out with a variety of different reactor conditions. However, ethanol and hydrogen are not the main products produced in this process, in fact ethanol and hydrogen are produced in relatively smaller quantities compared to other acidogenetic products such as volatile acids. This study aims to determine the optimum conditions for the formation of ethanol and hydrogen by controlling the initial pH of the reactor running and the addition oftrace elements Fe, Ni and MO as co-factorsfor enzymes that work in the process. The initial pH of the reactor was set at pH 4.5; 5.5; 6.5 and 7.5. The concentration oftrace elements used is 10 mg/L and 15 mg/Lfor Fe; 0.5 mg/L and 1 mg/L for M; and 0.25 mg/L and 0.5 mg/L for Mo. The study was carried out using palm oil industrial wastewater as a substrate, mixed culture bacteria originating from sludge in the palm oil industrial wastewater treatment plant combined with cow rumen in a ratio as biomass and carried out in the laboratory using a circulating bed reactor (CBR). operated at room temperature for 72 hours. Sampling is carried out every 6 hours to then analyze the resulting acidogenetic product. At the initialpH conditions ofthe reactors, the ethanol producedfrom each reactor increased until the 48th hour, and then tended to decrease. Reactor with an initial pH setting of5.5 can produce the highest ethanol compared to other reactors, which is equal to 369.53 mg/L. For reactors with an initial pH setting of 4.5; 6.5 and 7.5 respectively produced ethanol of 274.64; 256.50 and 253.71 mg/L. Setting the initial pH of the reactor also affects the hydrogen partial pressure (pH2) in each reactor. The highest hydrogen partial pressure (pH2) occurred in the reactor with an initial pH setting of5.5, which reached 15.43 kPa at the 60th hour. Trace elements Fe, Ni and MO are added as an effort to increase the production of ethanol and the resulting hydrogen. Based on the results ofresearch that has been done, it wasfound that the optimum timefor theformation ofhydrogen and ethanol occurredfor 48 hours in a reactor with a pH of5.5 and the addition of 15 mg/L-Fe of trace elements; 1 mg/L-Ni and 0.5 mg/L-Mo where the ethanol produced was 589.40 mg/L and hydrogen was 7.57% v/v. The addition of micronutrients Fe, Ni and MO can increase the formation of ethanol and hydrogen from the anaerobic waste treatment process. The Gompertz kinetic model is used to see the closeness between laboratory test results and the maximum product concentration that can be produced theoretically. The percentage comparison of laboratory test results with the Gompertz kinetic model shows the closeness between the results and the model, the higher the percentage, the closer the agreement between the laboratory test results and the kinetic model. The kinetic parameters used include Pm or the maximum concentration of the resulting product obtainedfrom stoichiometric calculations; Rm or product formation rate obtained from the experimental results; or the phase lag obtained from the experimental results. Based on the results of a comparison between the test results in the laboratory and the Gompertz kinetics model, it wasfound that the percentage ofhydrogen produced was 0.86% to 3.69% which occurred in the reactor with the addition of 15 mg/L-Fe; 1 mg/L-Ni and 0.5 mg/L-Mo, while the percentage ofethanol produced was 21.64% to 49.97% which occurred in the same reactor. This shows that the addition of these trace elements can produce ethanol, which is close to the kinetic model, but is not the optimum condition for hydrogen formation. Calculation of the energy balance which includes the energy of the products produced, the net energy balance (NEB) and the net energy ratio (NER) is carried out to evaluate the technical aspects of the bioenergy production process. Based on the calculation results, the energy value produced in each reactor with the addition of TE is greater than the reactor without the addition of TE, which only produces an energy output of 62.84 k.J. The reactor with the addition of TE can produce an output energy of112.27-189.88 k.J. The highest energy output occurs in the reactor with the addition of 15 mg/L-Fe, I mg/L-Ni and 0.5 mg/L-Mo. The NER value in the reactor with the addition of TE reached 0.650-1.099, while in the control reactor the NER value was 0.364. Thus, the addition of TE can be done as an effort to increase bioenergv production in the anaerobic processing ofpalm oil industry wastewater.