Turn waste, agricultural by-products into money

Date added: 24/12/15  |  Viewed: 2851

LTS: In response to the interest of the farmers in LCASP, Dr. Nguyen The Hinh (pictured), Director of the LCASP Project Management Board (Project Management Unit for Agriculture Projects, Ministry of Agriculture and Rural Development) NN-PTNT) has shared with NNVN Newspaper many good ideas to thoroughly treat waste of livestock and by-products in agricultural production and at the same time "turn" things ... to a valuable material. .

Biogas is not the only choice

According to the Department of Animal Husbandry, the livestock sector releases about 80 million tons of solid waste every year, but most of it is untreated or underutilized before being discharged into the environment. The Ministry of Agriculture and Rural Development sets the target that by 2015, 75% of rural households will have hygienic livestock cages and 18,000 animal farms with waste management systems. However, up to now, we have built and installed about 500,000 biogas plants.

Through surveys in 10 provinces participating in the LCASP project, we estimate that about 263,000 households have more than 10 heads of pigs or livestock but no biogas. Therefore, the demand in the people is very large. The LCASP project aims to build and install 36,000 small-scale biogas plants. Up to now, localities have achieved about 70% of the plan for the whole period of 2013-2018. Therefore, the leaders of MARD proposed to the Asian Development Bank (ADB) to increase the number of biogas tunnels to 50,000.

The ADB side has no idea what. As such, an additional 14,000 households will receive support from the LCASP project when constructing biogas reactors. Through inspection and evaluation, the project found that small-scale biogas plant works very well for the people. Because of the small size of Vietnamese livestock (10-15 individuals / household) and often mixed with residential areas. They installed a biogas plant of about 9 m3 is reasonable. In addition to addressing the environmental problem, the gas generated is used for cooking for the whole family.
One household in Ha Tinh told me: "The day before, when the price of high pigs, I raise. And when prices are low I do not raise them anymore. But since the biogas reactor, even when the price of pork hit the bottom, we still fed 4-5 pigs to take advantage of the family's leftovers and get cooking gas. That would cost you more gas, firewood. " So pig manure has become the main product in livestock, not by-products anymore. However, for medium and large farms, the farmer builds biogas plants with the capacity of several tens, hundreds, or even thousands of m3, the amount of gas produced is very large. It is worrying that we have not taken measures to use up this huge gas.

Recently I visited a farm in Ha Tinh, first they built a 49 m 3 tunnel, then made two HDPE covered trenches (250 m 3 and 300 m 3). Gas appliances generated were just two small stoves for 15 workers (theoretically, just one 49 m³ tunnel was enough), the rest of them said to burn off. The overall outlook is that this model is very polluting: 600 m3 of tunnels have insufficient fecal handling capacity of 4,500 pigs. At the same time gas from these tunnels does not use wasted organic resources, leaving methane out of the environment will produce greenhouse gases, 23 times more than the CO2 produced when aerobic fermentation. Thus, the biogas plant of the farm, though, reduces odors but increases the pollution of water and air.

In developed countries, when constructing large and medium-scale biogas plants, they take measures to treat excess gas by running generators and connecting them to the national grid system. Joint. However, in Vietnam this option is unworkable because most people use electricity from hydropower and thermal power plants due to their low price (subsidized by the state). Recently, the mission of the project management board came to China to refer to some models of biogas.

They invest in gas-powered systems to run generators, squeeze gas into cylinders for easy transportation to households, or squeeze into jars to run cars. However, those technologies require H2S purifiers. Because if not filtered, H2S gas will become very corrosive sulfuric acid in the machine very quickly. Typically, the price of a full-scale gas-based system includes H2S gas purification up to $ 1-2 million. Thus, the investment cost is too large so it is not feasible at present for Vietnamese farms.

From the above data it can be seen that biogas measures can not be the main solution to the livestock environment, especially medium and large scale farms. Because we have not formed the gas market to be able to use up all the gas produced. Therefore, people should not be recommended to biogas digester corresponding to the scale of livestock and should only be recommended to the people to biogas reactors to meet the demand for gas.

Dr. NGUYEN THE HINH

Director of the Central Low Carbon Project Management Board.

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