Pollution control in livestock farming is urgent, and method and cost are key
Recently, Yan Junfang, chairman of Yangling Benxiang Agricultural Industry Group, has been deeply troubled. Due to issues left over from the past, a farm under the group that can hold 200,000 pigs at full capacity has run into a thorny environmental protection problem. It is reported that the farm is only 170 meters away from the nearest surrounding village at its closest point. In the hot summer, the stench from the pig farm directly affects the daily lives of the villagers.
“No matter what the cost, I must handle the farm's environmental problems well.” Yan Junfang made a firm resolution.
Livestock and poultry farming pollution control brooks no delay
In recent years, with the rapid improvement of China's livestock and poultry farming level, the scale of farming has continued to expand, and the problem of livestock and poultry pollution has become increasingly prominent. To effectively solve this problem, the State Council also specifically issued the Regulations on the Prevention and Control of Pollution from Large-scale Livestock and Poultry Farming, giving legal basis to livestock and poultry pollution control.
The farming enterprises troubled by environmental pollution are by no means limited to the above-mentioned group. It is understood that many farms across the country are in the same predicament and anxiety, and there are quite a lot of them.
“If many enterprises still do not pay attention to farming environmental problems, then it will not merely be a matter of slowing down development speed, but they will face the danger of being shut down.” He Cheng, professor and doctoral supervisor at the College of Veterinary Medicine, China Agricultural University, who has long focused on and conducted considerable research on livestock and poultry farming environmental problems, told the reporter, “Livestock and poultry farming pollution control brooks no delay.”
Common pollution control methods abroad
In order to seek good strategies for solving the problem of livestock and poultry farming manure pollution, He Cheng made special visits to many countries to learn from other countries' advanced experience in treating livestock and poultry environmental pollution. During the interview, He Cheng introduced in detail the common methods abroad.
The first is the microbial fermentation method. Put the solid and liquid waste from the farm into a biogas tank, add anaerobic fermentation bacteria, and after 4 days of fermentation, biogas is formed, which is ultimately transported in the form of gas through pipelines to residents' homes or enterprises. In summer, the excess fermentation gas can also drive power generation for residents' lighting. The remaining solids after fermentation can be made into organic fertilizer after microbial fermentation, used for flower cultivation.
The second is the composting method. Mix livestock and poultry manure with straw, sawdust, etc. in a certain proportion, add suitable bacterial strains, stir thoroughly, and after 7 days to 8 days of fermentation, make it into organic fertilizer. To ensure the treatment effect, a shed can be built over the compost, which can both shelter it from rain and play a role in heating to promote fermentation.
The third is the coal chemical method. That is, extract humic acid and fulvic acid from lignite and add them to livestock and poultry feed to achieve the purpose of reducing the emission of odor from livestock and poultry manure. Or spray humic acid and fulvic acid on the surface of the manure. On the one hand, it can play an adsorption role; on the other hand, it is equivalent to wrapping the manure in a thin film to prevent the release of odor.
The fourth is to add microecological preparations to the feed, which can inhibit harmful bacteria in the intestinal tract of livestock and poultry, produce beneficial bacteria, and reduce harmful gas emissions during the formation of manure.
Pollution control cost is a factor that cannot but be considered
Which method has the best pollution control effect and is most suitable for widespread promotion in China? He Cheng believes that each method has advantages and disadvantages. “For example, the microbial fermentation method has the advantage of high comprehensive efficiency, but it has relatively strict temperature requirements. In cold seasons, it is relatively difficult to operate. The composting method has very low construction cost and is simple to operate, but after all, it is carried out in an open environment, and there will still be some odor during the process.” He Cheng introduced, “The coal chemical method is simple and easy to implement and is not limited by season, but its treatment efficiency is about 60% to 80%, and for waste with high liquid content, the treatment efficiency is relatively low. Although adding microecological preparations to feed can promote animal growth, improve animal immunity, and increase animal disease resistance, from the perspective of the effect of livestock and poultry manure pollution control, it is still low-efficiency operation.”
With such a dialectical analysis result, how should farms choose?
“Cost is an important criterion for measurement.” He Cheng said that if the cost of pollution control is too high, the enthusiasm of enterprises will be dampened. “For microbial fermentation, a biogas tank is indispensable. Although the treatment efficiency is very good, the repair and maintenance cost is relatively high. In China, the composting treatment model can currently be considered. For example, a dairy enterprise in Tianjin uses the composting method, transporting cow manure in a centralized way to a treatment plant and covering it with a shed outside. This cost is the lowest.”
He Cheng also pointed out that the transportation cost of waste such as manure is also an issue to consider. “We have discussed with German experts that wastewater can be discharged through pipelines at low cost. But chicken manure, pig manure, etc. must be transported by vehicle, and this expense is even more than the money subsidized by the state. This is the biggest problem we currently face, and there is still no good alternative.” He Cheng said frankly.