Rice hulls are tough to compost - we generally just spread them but now we are taking composting seriously, we will try more seriously from wikipedia
Production
Rice
hulls are the coatings of seeds, or grains, of rice. To protect the seed during the growing season, the hull is formed from hard materials, including opaline
silica and
lignin . The hull is mostly indigestible to humans.
Winnowing , used to separate the rice from hulls, is to put the whole rice into a pan and throw it into the air while the wind blows. The light hulls are blown away while the heavy rice fall back into the pan. Later
pestles and a simple machine called a
rice pounder were developed to remove hulls. In 1885 the modern
rice hulling machine was invented in Brazil. During the
milling processes, the hulls are removed from the raw grain to reveal whole
brown rice , which may then sometimes be milled further to remove the
bran layer, resulting in
white rice .
Use
Rice hull ash[edit ]
Combustion of rice hulls affords rice husk ash (acronym RHA),. This ash is a potential source of amorphous reactive
silica , which has a variety of applications in
materials science . Most of the ash is used in the production of
Portland cement [SUP]
[1] [/SUP] When burnt completely, the ash can have a blaine no. of as much as 3,600 compared to the blaine no. of cement between 2,800 to 3,000, meaning it is finer than cement. Silica is the basic component of sand, which is used with cement for plastering and concreting. This fine silica will provide a very compact concrete. The ash also is a very good thermal insulation material. The fineness of the ash also makes it a very good candidate for sealing fine cracks in civil structures, where it can penetrate deeper than the conventional cement sand mixture.
A number of possible uses for RHA include absorbents for oils and chemicals, soil ameliorants, a source of silicon, insulation powder in steel mills, as repellents in the form of "vinegar-tar" release agent in the ceramics industry, as an insulation material.
More specialized applications include the use of this material as a
catalyst support .[SUP]
[2] [/SUP]
Toothpaste
In Kerala, India- Rice husks (Umikari- in Malayalam)was universally used for over centuries in cleaning teeth - before toothpaste replaced it.
Brewing
Rice hulls can be used in
brewing beer to increase the
lautering ability of a mash.
Fertilizer and substrate
Rice hulls can be
composted , but their high lignin content can make this a slow process. Sometimes
earthworms are used to accelerate the process. Using
vermicomposting techniques, hulls can be converted to fertilizer in about four months.
Rice hulls that are parboiled (PBH) are used as a substrate or medium for gardening, including certain
hydrocultures . The hulls decay over time. Rice hulls allow drainage,[SUP]
[3] [/SUP] and retain less water than
growstones .[SUP]
[4] [/SUP] It has been shown that rice hulls do not affect
plant growth regulation .[SUP]
[3] [/SUP]
Fireworks
Rice hulls are coated with fine-grained
gunpowder and used as the main bursting charge in aerial fireworks shells.
Fuel
With proper techniques, rice hulls can be burned and used to power
steam engines . Some rice mills originally disposed of hulls in this way.[
citation needed ] Unfortunately the direct combustion of rice hulls produces large quantities of smoke. An alternative is to
Gasification . Rice hulls are easily gasified in top-lit updraft gasifiers. The combustion of this rice hull gas produces a blue flame, and rice hull
biochar makes a good soil amendment.[SUP]
[5] [/SUP]
Juice extraction
Rice hulls are used as a "press aid" to improve extraction efficiency of
apple pressing .[SUP]
[6] [/SUP]
Pet food fiber
Rice hulls are the outermost covering of the rice and come as
organic rice hulls and natural rice hulls. Rice hulls are an inexpensive
byproduct of human food processing, serving as a source of
fiber that is considered a
filler ingredient in cheap
pet foods .[SUP]
[7] [/SUP]
Pillow stuffing
Rice hulls are used as
pillow stuffing. The pillows are loosely stuffed and considered therapeutic as they retain the shape of the head.
Insulating material
Rice hulls themselves are a class A
thermal insulating material because they are difficult to burn and less likely to allow moisture to propagate
mold or
fungi .
SiC production
Rice hulls are a low-cost material from which silicon carbide "
whiskers " can be manufactured. The SiC whiskers are then used to reinforce ceramic cutting tools, increasing their strength tenfold.[SUP]
[8] [/SUP]
