Disadvantages of biogas digester

1, environmental temperature problem

Temperature is an important external condition for biogas fermentation. When the temperature is appropriate, bacteria multiply vigorously, their vitality is enhanced, anaerobic decomposition and methane production are faster, and more gas is produced. Generally speaking, biogas bacteria can ferment in the temperature range of 8℃ ~ 60℃. Biogas fermentation is usually divided into three fermentation zones according to temperature, namely, normal temperature fermentation zone:10℃ ~ 20℃; Medium temperature fermentation zone: 28℃ ~ 38℃; High temperature fermentation zone: 46℃ ~ 60℃. Practice has proved that in the temperature range of 15℃ ~ 40℃, the gas production rate increases with the increase of temperature. However, due to the large temperature difference between the four seasons in northern China, the average temperatures in winter and summer are -8℃ and 20℃ respectively, and biogas digesters are basically built underground. With the change of temperature all the year round, the pool temperature changes greatly, and the gas production rate also changes greatly, especially in winter, which even leads to the problem of no gas production or less gas production, resulting in the widespread existence of biogas in northern China for half a year. Therefore, keeping the temperature of biogas digesters appropriate and constant is the key technology, especially in cold winter, how to keep the temperature of biogas digesters is the key problem that affects the popularization and use of biogas in the north.

2. Management issues

The current management mechanism is imperfect and lacks quality awareness. Household biogas digester technology is a complex technology with strong professionalism and wide fields. It is particularly important to strengthen the quality management and daily operation management of biogas digesters. However, the overall scientific and technological quality of farmers is low, the management is scattered, the government's professional and technical team is obviously insufficient, and there is no effective socialized service mechanism and competitive incentive mechanism, so that biogas digesters can be built. However, poor operation and management lead to abandoned ponds, diseased ponds, secondary pollution and poor comprehensive utilization.

3. Technical problems

Technical training needs to be strengthened, as follows: first, the construction of cadres engaged in energy work needs to be strengthened, and the professional level needs to be improved. Most local managers and technicians have low theoretical level and lack of practical experience, and their ability to guide and manage local biogas construction is weak, which makes it difficult for technicians to find and eliminate the quality hidden dangers in pool construction. Secondly, there is a serious shortage of pool construction technicians. There are about 1300 technicians who have obtained the national certificate of "biogas producer" in each county, and they are lost due to various reasons 15-20%. Their technical level is uneven, because of cross-regional construction, it is common for technicians to carry out maintenance after construction. For serious and responsible technicians with good reputation, farmers who build pools compete for it. On the contrary, farmers are unwilling to accept it. The shortage of technicians has become one of the bottlenecks in completing the task of biogas construction. It is necessary to strengthen the training, rotation training and retraining of a large number of qualified technicians, especially the training of local talents. Third, it is necessary to strengthen the training of farmers. Farmers who build biogas generally have little knowledge of scientific management and comprehensive utilization and poor safety awareness, which leads to a considerable number of biogas digesters not achieving the best gas production effect.

4. Farmers' understanding is not in place.

Farmers are not only direct investors and operators of household biogas digesters, but also direct beneficiaries. Therefore, the economic benefits of technology determine farmers' enthusiasm for production, which is consistent with the government representing society. The benefits of household biogas digesters are mainly reflected in the ecological environment and social benefits, which are feasible from the perspective of government and society, but not from the perspective of farmers. In addition, the bad work style of government staff causes the attitude and behavior of farmers and the government to build ponds to be inconsistent, and the enthusiasm of farmers is not as high as that of the government. Therefore, the current development of household biogas digesters must first change the concept, change the starting point and foothold of biogas technology application, pay attention to economic benefits, vigorously develop comprehensive utilization technology of biogas, develop efficient agriculture and improve economic benefits, so that biogas production will have vitality and development potential. From the government's point of view, it will be beneficial to the further development of biogas technology to actively guide and do everything possible to raise funds and give farmers some economic compensation.

5. The problem of insufficient funds.

According to the national debt project biogas construction standard, the total investment of building 10m3 biogas digester 1 household needs more than 3,000 yuan. In addition to national debt subsidies and local matching funds 1 1,000 yuan, users need to raise about 2,000 yuan by themselves. However, most farmers who are suitable for building biogas digesters mainly rely on the income from agriculture and animal husbandry, and their per capita income is low, raising 2,000 yuan by themselves, which is unbearable for farmers. In addition, some farmers have the idea of "waiting, relying and wanting", which causes certain difficulties to the project and directly affects the construction of biogas digesters.

6. The standard of pool construction is low, and the utilization rate of biogas in winter is poor.

I used to build biogas digesters in our province, mainly cement pools. Due to the low temperature in winter in our province and the low temperature in the pool, there are some problems such as little or no gas production. In addition, due to the poor quality of pool construction and daily maintenance, biogas digesters often freeze and crack in winter. It brings difficulties to the use and popularization of rural biogas.

7. The follow-up service system is not perfect, and there are many sick and waste pools.

Due to the imperfect system, insufficient funds, and unfocused clients, the current service system is not perfect, which makes the farmers who have built biogas digesters unable to get effective services, and some of the biogas digesters can not be used normally, which discourages the enthusiasm of farmers to build pools and affects the progress and popularization of biogas digesters. This is mainly due to the large amount of tasks in the initial stage of the project, few skilled workers, backward pond type, low quality of pond body construction, irregular installation, improper use of pond body construction by farmers, disjointed follow-up services, migrant workers, reservoir resettlement, urban construction, highway reconstruction and other reasons.

8. There is little research on the application technology of biogas comprehensive utilization.

At present, the comprehensive utilization of biogas in our province is mainly based on building ponds and promoting energy ecological models. The use of biogas is limited to cooking, boiling water and other cooking purposes; The specific application technology of biogas residue as base fertilizer, biogas slurry soaking and seed dressing, foliar spraying and feed additive is less studied. The utilization rate of biogas residue and biogas slurry is very low, which greatly affects the comprehensive benefit of biogas and wastes resources.