Improving the Quality of Biogas Fuels with Natural Zeolites

biogas

Human dependence on fossil fuels causes reserves of energy sources is increasingly diminishing, besides it also impacts on the environment, such as air pollution. Fossil fuels or mineral fuels are natural resources that contain hydrocarbons such as coal, petroleum, and natural gas. 

Fossil fuels are formed because of the natural process of decay from organisms that died hundreds of millions of years ago. Dinosaurs, trees, and almost all living things that died were deposited on the ground and now have become petroleum, natural gas, or coal. Natural gas has the form of gas, liquid petroleum, and solid coal. due to differences in the pressure and heat, they receive in the bowels of the earth over millions of years ago.

Fossil fuels are a kind of non-renewable natural resource. Because this fossil fuel is formed from the process of sedimentation and decomposition of living things and takes millions of years. 

This makes many people aware that dependence on fossil fuels must be reduced immediately. To overcome this problem, alternative fuels that are cheap and easy to obtain are needed. One of the alternative fuels is biogas. 

Biogas is a gas produced by anaerobic activity or fermentation of organic materials including human and animal feces, domestic (household) waste, biodegradable waste, or any biodegradable organic waste in anaerobic conditions. The main material in making biogas are Methane and Carbon Dioxide. Biogas also can be used as vehicle fuel or to turn on electric things.

Biogas is reprocessed into more specific fuel oil. The process of purification (purification) of natural gas or often also called the process of gas purification is carried out with the aim of removing/separating impurities (impurities) that are not desired in the natural gas. Before the purification process is carried out, natural gas obtained from the well must first go through a testing phase in the laboratory to find out the chemical compounds that are dissolved in it. This is needed to determine the purification process, the number of processing units, the type of chemical, and the chemical dose to be used. The addition of activated carbon in raw materials in the form of cow dung serves to increase the C / N ratio, which can improve the anaerobic digestion process and obtain optimum conditions in producing methane gas. The study also used a CO2 scrubber with a solution of Ca (OH) 2 (lime water) and KOH solution.

Biogas is produced through the process of fermentation of organic waste such as garbage, food scraps, animal waste and food industry waste. The elements contained in biogas are methane gas (CH4), carbon dioxide gas (CO2), oxygen gas (O2), hydrogen sulfide gas (H2S), hydrogen gas (H2), and carbon monoxide gas (CO).

Of all these elements that play a role in determining the quality of biogas, namely methane (CH4) and carbon dioxide (CO2) gas. If the CH4 level is high, the biogas will have a high heating value. Conversely, if CO2 levels are high, the biogas calorific value will be low. Therefore to increase the heating value of biogas the CO2 gas content must be low. The content of methane gas (CH4) from biogas can be increased by separating corrosive carbon dioxide (CO2) and hydrogen sulfide (H2S) gas from biogas.

To overcome this problem, many attempts were made to refine biogas. Researchers studied the biogas purification process using zeolite which was activated with a solution of NaOH and the zeolite was modified by mixing several materials such as bentonite, kaolin, limestone, tapioca/starch, and liquid chitosan. In addition, other efforts have also been made to improve the quality and quantity of biogas, namely the addition of activated carbon and the use of CO2 scrubbers.

Read: Zeolite Uses In Agriculture

An interesting method of biogas purification to be studied is by using adsorbents. The adsorbent is a substance that can absorb fluid, both liquid, and gas so that later it will form a thin layer on the surface of the substance. One type of adsorbent that can be used is zeolite.

Zeolite was chosen because besides being easily obtained, the price was also quite cheap. So that the zeolite adsorption process takes place faster than before the activation process should be done first. The activation process can be done in two ways, namely physically with the heat treatment process and chemically using an acid or base solution. One type of chemical that can be used for the chemical activation process is potassium hydroxide (KOH) or its Latin name, Potassium Hydroxide. KOH is a strong base compound that is stable and dissolves easily.

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