Application of Biogas with Fermenting Bacteria from Manure Raw Material on Stoves and Generators

. The raw biogas from the digester is a gas produced by bacterial fermentation which has a composition of methane (CH4), carbon dioxide (CO2), hydrogen sulfide (H2S), water vapor, and various other gases. Gases other than methane in raw biogas can damage the combustion system if used directly. The digester that produces biogas is used to move the generator engine using raw materials, such as cow feces, goat feces, fowl feces, straw, husks, and clean water. In the mixing process, all the raw materials are stirred or mixed evenly in the digester. Next is the process with five stages, namely (1). In the first stage: on the 11th day, adding clean water and fermentation carried out for 21 days, (2). The second stage: adding starter, hormones, charcoal flour, cow feces, fowl fees, goat feces, straw, and husks, then fermented for 7 days. (3). The third stage: adding a starter and fermenting it for 7 days. (4). Fourth stage: ready-to-use compost or solid fertilizer is ready to produce. (5). Fifth stage: liquid fertilizer is ready for production. In the gathering stage: all raw materials are stirred or mixed evenly in the digester and fermented for 1.5 months to become biogas. The last stage is the distribution of biogas: for household needs, and generators. From this research, it can conclude that the water column height (h) is 10.42 cm, and the maximum water column height is 9 cm so that the reactor is safe and the maximum pressure that can be attained is 879.1918 kg.m -1 .s -2 . The heating rate for ratio A is 0.0600 o C.s-1 and the heating rate for ratio B is 0.0640 oC.s-1. The calorific value produced from heating 1 liter of clean water using biogas from ratio A is 297.99315 kJ, and the calorific value of ratio B is 288.9174 kJ. With a compressor pressure of 8 psi, biogas can be inserted in this using a freon tube for a maximum of 6000 seconds with a mass of 6163 grams. In filling biogas, the biogas manometer should show the maximum number (between 16.50 – 25.50).


INTRODUCTION
The results of biogas from animal dung, straw, and husks that are currently of biogas are alternative because there is no gas cylinder as a biogas storage that can be used by others as a substitute for LPG (Liquified Petroleum Gas), I hope for the biogas results Can be stored in a gas cylinder instead of LPG, due to the importance of the use of gas in the household.The object of research is to get the gas results obtained from biogas of animal dung, straw, and husk stored in used tubes that can be stressed so that animal dung, straw, and husk produced every day is not wasted.So that biogas energy is in waste, the biogas tube can store biogases of an animal, as husk utilized as needed.
Cow feces is one of raw materials's sources for biogas production.Furthermore, the content of methane gas (CH4) in cow dung is 65.7% (Wulandari & Labiba, 2017).The high content of this gas from cow feces can be used as raw material for making biogas (Wulandari and Labiba, 2017).The composition of the gas produced from cow dung is shown in this table.
In addition to the high cellulose content in cow feces, the thing that must be considered for the raw material for making biogas is the content of the C/N ratio.The following contains the C/N ratio of animal feces: Cow feces as livestock waste is used as a source of C and N in methane gas formation.Cow feces as the primary stuffing item has a C/N ratio of 22.12 to 25 (M.Quraish Shihab, 2020).Every 1 kg rice straw can produce 0.20 -0.38 m 3 of biogas.The energy produced by biogas can be used for cooking, lighting, and cooling the motor drive.The energy from 1 m3 of biogas can be used to run a 1 HP engine for 2 hours; provide 1.25 kWh of electricity; provide energy to cook three meals for five people per day; provides the equivalent of 60 watts of illumination for 6 hours; Turn on the refrigerator for 1 hour.The process of making biogas with rice straw through inserting rice straw and cow feces into the digester tank with as much as 8 kg of dry materials with a ratio between rice straw and cow feces is 2: 1.Next is adding water so that the water content's substrate becomes 90%.The fermentation process was carried out for 35 days.Every five days, before using it, stirring is carried out so that all substrates are perfectly mixed, and the formation of scale will be avoided.Stirring is moving the iron pendulum in the digester through a connecting rope made of steel wire.The substantial component of rice straw is cellulose (35 -50%), hemicellulose (20 -35%), lignin (10 -25%), and other substances.The two polysaccharide materials (cellulose and hemicellulose) can be hydrolyzed into simpler compounds.The results of the hydrolysis can be fermented into methane (CH4), which is the main component of biogas.One of the factors that influence the formation of biogas from biomass is the C/N ratio.The higher the C/N, the slower the decay time, while the lower the ratio increases the production of ammonia which is toxic to bacteria, caused by excess nitrogen residue.A good C/N ratio is 30, this is because bacteria consume carbon (C) 30 times faster than nitrogen (N).

Biogas for Stove and Generators
Biogas is a fuel from an anaerobic process using a digester often used for cooking and can be used as fuel for generator sets ((Ningrum, et. al., 2017).Methane gas has a very high calorific value of 4800 kcal/ m3 to 6700 kcal/m3, while pure methane gas has an energy of 8900 kcal/m3 so that biogas can be used for lighting, cooking, and driving machines Equivalence between biogas and other energy sources, that is, for every 1 m3 biogas is equivalent to liquefied petroleum gas ( LPG) 0.46 kg, 0.62 liter diesel, 0.52 liter gasoline, 0.80 liter kerosene, 3.5 kg firewood (Irawan & Ridhuan, 2017).
Today the use of biogas is not only used as fuel for stoves but can also be used to generate electricity using a generator.However, in its development, the application of power plants using biogas fuel is still limited (Aisyah & Herdiansyah, 2015).Household-scale biogas power generators are a promising technology for supplying electricity to remote and isolated areas in Indonesia.The components of a small-scale biogas power plant system consist of a digester anaerobic to produce biogas, generator engines that have been modified to be able to use biogas fuel, desulfurized units to reduce H2S levels which are corrosive to generators, and water trap units to reduce biogas water content (Haryanto, et.al., 2020).

METHODS
The research method and flowchart that describes the stages of the activity are as follows: a. Flow diagram of the biogas production process until household needs and generator distribution; b.Digester installation components until household stoves and generator distribution; c.
Functional testing of design and construction results; d.Testing the drying system and drying characteristics of rice.

• Tools
The tools used in this study are as follows: a.A digester equipped with a stirrer is used to make biogas from mixing, and fermentation until storing the biogas; b.Manometer used to measure biogas pressure in the fermentation process of the sample; c.Thermocouple is used to measure sample temperature in the digester; d.Litmus paper or pH paper is used to measure the pH of the sample before starting the fermentation process; e. Stopwatch used to measure the time of sample stirring and biogas flame testing time; f.Scales are used to weigh the mass of the sample; g.Measuring cup is used to determine the volume of water; h.Second-hand Freon tubes are used to store biogas before using it to fill the stove and generator; i. Biogas stove used for testing the biogas flame; j.Genset is used for household lighting backup if the lighting from PLN goes out.

Materials
The raw materials used are cow feces, goat feces, fowl feces, straw, husks, clean water, charcoal flour, starter, and hormones, and they will be mixed until evenly distributed in the digester.

Standard Operating Procedures
The research will be carried out as follows: a. Prepare all the necessary raw materials, such as cow feces, goat feces, fowl feces, straw, husks, and clean water; b.Freshly harvested rice straw with 65% moisture content and cut it into 10 -15 cm long.Then, stack them in a place with a height of 20 cm.Sprinkle urea and probiotics evenly with a dose of 5 kg of rice straw; c.Second-hand rice husks from milling rice are weighed around 5 kg; d.Cow feces, goat feces, and fowl feces are weighed around 5 kg; e. 10 liters of clean is measured using a measuring cup; f.Mix the raw materials, such as straw, husks, cow feces, goat feces, and goat feces, and mix them thoroughly until evenly for 10 minutes with a rotating speed of 340 rpm, and repeat it one more time in 2 days for 10 minutes with speed 340 rpm; g.Store the mixture in a fermentation reactor (anaerobic process) for 45 days.

RESULTS AND DISCUSSION
The results of biogas from two types of reactors are as follows.Based on the table above, it is seen that the addition of a larger ratio of rice husks does not directly increase the productivity of methane gas, because the addition of 0.10% volume of slurry in the digester shows a decrease in the methane gas productivity and an effect on a decrease in biogas temperature at ratio A. with the slurry temperature, and will be the same with the decrease in methane gas productivity and affect the decrease in biogas temperature in the ratio B to the slurry temperature.7 above from the first day to the 45th day of the biogas pressure data for ratio B increase from 3.14 to 3.47 Pa from the pressure in ratio A. In Table 8 above regarding data on the accumulation of gas volume from the first day to the 45th day, the gas volume has an increase from the A ratio from 0.0000 to 0.2711 m 3 , and the gas volume accumulation data from the first day to the 45th day the gas volume has an increase from the ratio B ranges from 0.0000 to 0.3865 m 3 .

 Pressure safety valve
The data obtained from the two biogas reactors is the maximum pressure (P) from the difference between reactor B minus reactor A on the 45th day, which is (102343.19-101325) = 1018.19Pa = 1018.19kg/m.dt2, with polyethylene plastic density (ρ), is 995.8 kg/m3 (Indartono, 2005).By using the equation below, the height of the water column used to maintain the pressure in the reactor so as not to exceed the strength of the polyethylene plastic is: P=ρ.g.h ….. ( 2 For the maximum height of water column to be made is 9 cm, so that the reactor is safe and the maximum pressure that can be achieved is (995.8kg/m 3 x 9.81 m/s 2 x 0.09 m) = 879.1918kg/m.s 2 = 879.1918Pa.

 Fire safety valve
The fire safety valve has a function to prevent fire from returning to the biogas installation by placing the fire safety valve in the line after the reservoir before the stove and the generator.The valve is made with plastic tape wear for the water reservoir and 0.5" = 1.27 cm PVC pipe for the line.

 Biogas Combustion
Test of data retrieval for the calculation of the heating rate using 1 liter of clean water heated with a fire produced by the reactor from the slurry.The composition is with a ratio of 1:1 (for cow feces, goat feces, and goat feces with clean water) without rice husks and the addition of straw with a 0.20 ratio and the slurry volume with a 0.25 ratio.The calorific value produced by heating 1 liter of clean water using biogas from each ratio is: Q = V water × ρ × C p × ∆T ….. (4) Q = 0.001m 3 × 995.8 kg m 3 × 4.2 kJ kg.K ⁄ ⁄ × (371.75 − 300.5)KQ = 297.99315kJ Furthermore, the calculation of the other ratio is shown in Table 11.

Figure 1 .
Figure 1.Flow chart of the biogas production process until distribution to household stoves and generators.
All material are mixed evenly into the digester and fermented for 1.5 months untul become biogas.

Figure 2 .
Figure 2. Digester installation components until distribution to household stove and generator

Table 6 .
Data of environment temperature, biogas temperature, and slurry temperature from the research Slurry contains a ratio of liters of cow feces, fowl feces, and 10 liters of clean water • Ratio A: volume of slurry without husk and straw • Ratio B: slurry + husk + straw with 0.1 volume from slurry's volume divided by slurry

Table 7 .
Data of pressure on the gas

Table 8 .
Data of gas volume accumulation from to day

Table 9 .
Data of water temperature test from both biogas ratio

Table 11 .
The calorific value for ratio A and B

Table 12 .
Data of gas filling test