How to build biogas digesters in rural areas?

Rural biogas is a popular project with green environmental protection, energy saving and high efficiency. using biogas engineering technology to treat human and animal manure can not only effectively solve the energy problem of rural life, but also obtain organic fertilizers needed for agricultural production and improve the living environment in rural areas. with good economic, ecological and social benefits, let's take a look at how to build biogas digesters in rural areas.

Basic requirements

Rural household biogas digester is a device for producing and storing biogas. The quality, structure and layout of biogas are directly related to the production, use and management of biogas. Therefore, the construction of biogas digester should be reasonable in design, simple in structure, convenient in construction, strong and durable, and low in cost. In some places, due to the lack of experience, they do not pay enough attention to the quality of the pool, so that after the pool is completed, it leaks air and water, which can not be used normally and becomes a "sick pool". Some biogas digesters are too large and deep, the effective utilization rate is low, and it is not convenient to discharge. Years of practical experience has proved that the structure of biogas digester should be "round" (round pool), "small" (small volume) and "shallow" (shallow depth of the pool). The layout of biogas digesters is mostly "three-in-one" (toilet, pigsty, biogas digester) in the south, and "four-in-one" in the north (toilet, pigsty, biogas digester, solar greenhouse).

Material preparation

The construction of an 8 cubic meter biogas digester requires 1 ton of cement, 2 cubic meters of sand, 0.6 cubic meters of gravel (1 cm), 600 red bricks, 2 ceramic pipes (20 cm in diameter) and 1.2 meters of steel bar (14 mm in diameter). If 10 cubic meters of biogas digester is built, the cement, brick and sand will be increased by 10%. If 6 cubic meters of biogas digester is built, the amount of cement, brick and sand will be 10% less than that of 8 cubic meter biogas digester.

Put out the line to dig the hole

Laying off the line and digging the pit is the first step to ensure the quality of the pool, and it must be constructed according to the prescribed size. The key point of laying out: ① draws the overall plane. ② delineates the area of greenhouse and pigsty, which is on the east or west side. ③ draws the centerline of the "mode" width. ④ takes O as the starting point, finds out the center point O of the pool on the inside of the piggery, takes O as the center, and draws a circle with the radius of the pool plus 6 cm as the radius to determine the location of the pool. ⑤ determines the position of feed inlet and outlet. To determine the center point of the feed inlet and the center point of the discharge port located in the solar greenhouse on the width centerline of the "mode", mark it with white ash.

Pit excavation

1. The biogas digester built in the "mode" adopts underground buried type, and the earthwork of biogas digester adopts the construction technology of large-scale excavation. First of all, the height of plus or minus zero should be determined. The depth of the pit is determined according to the design drawing, that is, the top of the biogas digester and the discharge outlet are kept on a horizontal plane and 10 cm higher than the pig house floor. If the feed inlet is super high and the ground is 2 cm, if the biogas digester is dug too deep to make the biogas digester below the ground level, it will affect the matching use, dig too shallow to make the biogas digester protrude from the ground, and it is difficult to feed pigs and fertilize in the solar greenhouse.

2. In order to facilitate the placement of the pool mold or the use of brick mold to build the pool body to reduce material loss, the pool pit should be round and vertical. For areas with good soil, the pit wall can be dug straight, dig from the middle to all sides when the soil is taken, and leave some leeway when excavating to the pit wall, then find out the central point according to the positioning pile and nail a fixed wooden stake, fix one end of a rope to the wooden pile at the central point, and tie a small hoe to the other end of the rope, so that the length of the hoe to the central point is equal to the radius of the pool and the thickness of the wall is 6 cm, scraping off the sand that hinders the passage. Dig and trim the pool pit until the design depth.

3. Immediately after the pit is dug, the bottom of the pool will be modified into the shape of the bottom of the pot, and a U-shaped shallow groove will be dug from the center of the bottom of the pot to the bottom of the water pressure room, with a downward slope of 5%. For places with loose soil, 80 cm below the ground should be sloped to take soil, and the slope depends on the degree of looseness of the soil, based on the principle that the pit wall does not collapse, and dig the pit at the same time. If there is groundwater, a collecting pit should be dug at the bottom of the pool for drainage.

4. When the groundwater is encountered during the construction of the pool, the method of "avoiding, diverting and blocking" can be adopted.

① avoidance: "avoidance" is to avoid groundwater, try not to construct in rainy seasons, choose places with lower groundwater level and higher terrain to build ponds, and water network areas can build spherical ponds or raise the body of the ponds to build semi-underground ponds.

② introduction: "diversion" is to divert groundwater and dig drainage ditches before construction to divert water away as far as possible. Pool wall seepage, bamboo pipe can be inserted into the seepage place or in the pool wall star ("Y")-shaped trench, so that the water is concentrated from the ditch to the bottom of the pool. For the water seepage at the bottom of the pool, a cross ditch or annular ditch can be used to collect water, and a small deep well can be dug in the middle of the pool bottom to make the water flow into the well and be swabbed away, and the well can be filled when there is no seepage discharge at the end of the project.

③ plugging: "plugging" is to block the groundwater. For individual springs in the pool, bricks and small stones can be used to plug tightly.

Note: if there is water seepage in a large area, the water glass liquid impervious agent can be mixed with cement for painting, rapid solidification and effective blockage. At the same time, when a pool is built in the place where the soil quality is poor and the groundwater level is high, a sand pebble cushion must be set up under the pool bottom. the construction of the cushion can first be paved with pebbles, and then the sand can be filled with pebbles by water sedimentation method to ensure the quality of the pool construction. If there is no groundwater in the pool construction site, cushion and drainage measures may not be added below the bottom of the pool.