Rice hulls (also called rice hulls, English: rice hulls) is the hard shell covering the grain. In addition to protecting rice grain during the growing season, rice husks can also be used as construction materials, fertilizers, insulation in construction or fuel. Husk husk is used to line the barn very effectively for the farming farmers, with high water absorption 7-14 liters / kg coco peat always keep the pen clean and dry.
Moreover, after the period of lining the barn, animal wastes along with rice husk create a very good fertilizer for plants, especially leafy vegetables, pepper, cashew, coffee….
Help improve soil to make the soil porous and open, increase soil fertility, stimulate deep root development.
In addition, people also use rice husk to produce organic fertilizer to fertilize rice husk charcoal, used as fuel. Rice husks in the North will be mixed with manure, soil and NPK to form a common soil for vegetables.
Currently, rice husk is used as a medium for hydroponic quite well when combined with coconut fiber, pearl stone.
Advantages of Rice husk:
-Improve the situation of fallow - fibrous soil.
-Maintain moisture and increase soil nutrition.
-Increase aeration of the soil.
-Promote root development and help plant growth.
- Contains natural organic substances that are good for soil and plants.
-No harm to the environment.
There are 2 types of rice husk
1. Processed is burned in an anaerobic environment called husks.
2. Untreated fresh rice husks are often mixed with soil and used as a breeding environment.
Now available in 80dm3 packaging (weighing about 10 - 15kg / bag) convenient for everyone to grow vegetables on the terrace.
The origin of rice husk Rice (Oryza spp.) Is one of the five major food crops of the world, along with corn (Zea Mays L.), wheat (Triticum sp. Other names: microcircuits), cassava (Manihot esculenta Crantz, another name for tapioca) and potato (Solanum tuberosum L.). The product obtained from rice is paddy. After removing the outer shell, the main product is rice and the by-products of bran and rice husk. Rice husk is the outer layer of rice grains and is separated during milling. In the husk contains about 75% substance
Situation of rice husk in Vietnam
Rice husks are abundant in the Mekong Delta and the Red River Delta, the two largest rice growing regions in the country. They are often not used up, so they must be burned or poured into rivers and streams to destroy. According to the survey, the amount of rice husk discharged in the Mekong Delta is more than 3 million tons / year, but only about 10% of it is used.
In winter-spring and summer-autumn crop, rice husk price is only around 150,000 dong / ton, in this autumn-winter crop, rice husk price has doubled. Currently, prices range from 450,000 to 500,000 VND / ton, an increase of around 300,000 VND / ton, due to the fall-winter crop of rice output decreased compared to the winter-spring and summer-autumn crop so the source of rice husk is scarce, insufficient supply for many rice husk processing facilities for export inside and outside the province.
Common names: Rice husks, rice husks planted
Price per bag: 150 dm3
Bag size: 80 cm high; Horizontal 60 cm; 30 cm wide.
The application of current rice husks
Use rice husk as fuel
For a long time, buffalo shells have been a very familiar fuel for farmers, especially farmers in the Mekong Delta. Fuel from rice husks is used a lot in both domestic activities (cooking, cooking animal feed) and production (brick making, rice drying). Rice husk is a very abundant and cheap source of raw materials: The country's rice output in 2007 reached 37 million tons, of which, winter-spring rice was 17.7 million tons, summer-autumn rice was 10.6 million tons, rice in season 8, 7 million tons. Thus, the amount of rice husk obtained after milling is equivalent to 7.4 million tons.
The composition is high molecular fiber, which is difficult for microorganisms to use, so storage and storage are simple and cost little.
Use rice husk to filter water
In Hai Duong city, there was a person who invented a way to make a device to filter water from rice husks, which can filter straight water from ponds and lakes into clean drinking water. At the core of the device is a white, cylindrical porcelain cluster in the filter. The special thing is that this porcelain is created by separating silicon oxide from rice husks, has extremely good filtration properties, with micro filtration holes, which are 10 times smaller than American ones, 4 times larger than Japanese ones. It is also highly durable (can be used for 10 to 20 years).
The device is also capable of eliminating odors in polluted water, eliminating dioxins when being connected in series with a filter tube with activated carbon filter.
To test the effectiveness and safety of the water filter, Hai Duong Preventive Medical Center took a sample of water from Bach Dang Lake, a heavily polluted area in Hai Duong city, which was treated by a magnetic filter. rice husk. The results showed that: after treatment, lake water met hygiene standards of drinking water about microbiological criteria.
On the other hand, the maintenance of the filter element is quite simple, just use a cleaning cloth or washcloth to clean the white filter element, the original filtering speed.
Use rice husk to form firewood
The rice husk firewood press is produced in Go Cong (Tien Giang) with a capacity of 70 - 80 kg of firewood / hour, consuming electricity at 6 - 7 KW / h. For every 1.05 kg of rice husk, 1 kg of rice husk firewood is produced. Just put rice husks into the machine throat, through the presses, the machine produces rice husks. Husk firewood has a diameter of 73 mm, length from 0.5 - 1 m. 1 kg of rice husk fire can cook meals for 4 people.
Gia Vien district, Ninh Binh people have created interior handicraft products from rice husks. The husk of the grain (rice husks) is finely ground to form a fine powder and fiber powder. After combining with glue, rice husks are put into molding machine to shape products and dry, perfect ... Application of rice husks for biogas production (rice husk gasification).
In recent years, renewable energy technology in general, especially biomass energy technology (Biomass: firewood, rice husks, corn pulp, peanut shells, sawdust, shavings ...) has been developing very strongly.
Biomass energy technology not only substitutes partly for fossil energy but also contributes significantly to waste treatment. Sources of waste - agricultural by-products (both after harvest and after processing) such as straw, rice husk, coffee husk, coconut fiber, bagasse ... in the country are estimated at over 30 million tons / year.
Therefore, exploiting the potential of renewable energy from agricultural by-products (including rice husks) is a strategic direction and employment that has significant socio-economic development and environmental protection.
Rice husks in the Mekong Delta as well as the whole country are being used for cooking and burning furnaces for burning bricks, ceramics, drying agricultural products, etc. mainly by direct burning on a grate. This type of combustion is accompanied by smog, causing heavy pollution to the environment. This is really a problem for most localities and industrial parks. Changing the combustion process is the solution to tackle the source of pollution. Consistent with the trend of industrialization and modernization of our country and in line with the trend of the world in general.
One of the solutions to change the combustion process is rice husk gasification (or other Biomas products). Use that generated gas to burn like normal LPG.
Gasification is the conversion of a solid or liquid material into a useful and convenient gas fuel for burning to release energy.
During the gasification process, the material is heated to a high temperature → resulting in a change in physical and chemical properties → creating volatile flammable products (Co, H2 and CH4) and wastes such as ash, tar
Rice husks can also be used as clean construction materials
Torftech Group of England said, after burning every ton of husk will produce 180 kg of ash, valued at USD 100, can be used as an additive for cement and can directly replace SiO2 in cement. .
Naturally, scientists have long discovered that rice husks are valuable when used as building materials. In rice husk contains a lot of SiO2, which is the main ingredient in cement, but people want to take advantage of the ash after burning rice husk as a substitute for cement, this method will create Carbon content in rice husk ash is very high, can not replace cement components.
Recently, according to Discovery, with the support of social science funds, US scientists have discovered a new method of processing rice husks, which can simultaneously use rice husk ash as an ingredient in cement, promoting the development of clean construction materials.
Texas State Corporation CHK said they now have teamed up with a research team and found a method of almost no carbon in rice husk ash component. This new method is to husk husk into the incinerator, burn at a temperature of 8000C, only the remaining SiO2 particles of high purity. At the conference on clean chemicals and structures held at the University of Maryland Park campus, the school's team introduced their research results. Even though burning will produce CO2, it is generally Neutral Carbon, because the amount of Carbon will be eliminated by new rice products every year will absorb them.
In fact, the use of concrete and consumption pose a difficult problem when causing climate change. For every ton of cement used to produce concrete, one ton of CO2 is emitted from the air. But worldwide, the production of cement accounts for 5% of carbon emissions in all human activities.
The reason for husk ash can not be used as a main component in cement is because the carbon content is too high. If this problem can be solved, rice husk ash will become a good raw material for concrete, thereby reducing the amount of carbon released from the concrete industry. Research results show that, in concrete, more rice husk ash will be stronger and more resistant to erosion. The team predicts that repairing high-rise buildings, piers or any structures near the sea or on water, if husk ash is used to replace 20% of cement, it will be very effective. high for concrete.
If the production of rice husk ash is stable, utilizing all sources of rice husk ash in the United States, the amount of rice husk ash can be obtained 2.1 million tons / year. In fact, for developing countries with huge consumption of rice and concrete, such as China and India ... the potential of rice husk ash is very high.
In addition, researchers at the University of Bath and Dundee, along with their colleagues in India, are also developing environmentally friendly cement from the use of waste materials such as rice husks.
Portland cement, the main component of concrete is produced by calcining limestone with clay at high temperature, each ton of cement produced emits about 1 ton of CO2.
Researchers are working on ways to reduce carbon emissions by replacing part of portland cement with waste materials such as fly ash from coal combustion, slag in steelmaking and even rice husks. Concrete is the second most used material in the world after water, so CO2 emissions from concrete can have a major impact on climate change. Currently, infrastructure in India is growing rapidly and India is the 2nd largest cement producer in the world after China. Therefore, this project in cooperation with research institutes in India is deploying new technologies in countries with the highest cement demand.
To replace part of Portland cement, some "green" cement needs to be researched using various locally available waste materials. For example, in India, silicon dioxide can be produced from burning rice husks to mix into cement; In the UK, fly ash generated by coal burning can be used.
Therefore, if we know how to overcome to reduce the amount of carbon in the husk, there can be a large amount of SiO2 particles in our country because our country is the 2nd largest rice exporter in the world and from there can be studied. Application on cement replacement to reduce environmental pollution.
Activated carbon from rice husk
Biomass is made from carbon rich materials such as peat, coal, plants (wood, sawdust, bagasse ...), animal bones.
Other applications of rice husks
Some other applications of rice husks: Not stopping at the above applications, rice husks can also be used as insulation, fillers and media in the production of spawn for growing mushrooms, polishing objects. In metal form, rice husk ash can be used as fertilizer.
Rice husk can be applied very differently in the life of Vietnamese people. Rice husk has a great advantage in terms of raw materials and price, so the research to use rice husks in production always brings high economic efficiency and cost savings. In fact, in some provinces, especially in the Mekong Delta, rice husk is still very abundant, so it is important to pay attention to the research and application of this material to expand the ability to use rice husks while saving costs. production, medium beneficial to the environment.