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By Translated and summarized by Bioagro
Every year, agricultural effluents, industrial wastes, and industrial accidents pollute surface waters, soils, air, streams, and reservoirs. A new composting technique, known as Bioremediation compost, is currently being used to restore contaminated soils, manage stormwater, control odors, and degrade volatile organic compounds.
Compost Bioremediation refers to the use of a biological system of microorganisms, in mature compost, to sequester or destroy contaminants in water or soil. Microorganisms consume pollutants from the soil, surface and groundwater, and from the air.
The pollutants are digested, metabolized and transformed into humus and inert products, such as carbon dioxide, water and salts. It has proven effective in degrading or altering many types of contaminants, such as chlorinated and non-chlorinated hydrocarbons, wood preservative chemicals, solvents, heavy metals, pesticides, petroleum products, and explosives. Composts used in Bioremediation are referred to as custom-made or drawn, in the sense that they are made especially to treat specific contaminants at specific sites.
The ultimate goal in any remediation project is to return the site to its precontamination condition, which often includes reforestation or revegetation to stabilize the treated soil. In addition to reducing contamination levels, compost advances its goal by facilitating plant growth. In this role, compost provides soil conditioning, and also provides nutrients to a wide variety of vegetation.
Heavy metal contamination
Dr. Rufus Chaney, a Sr. Agronomic Researcher from the US Department of Agriculture, is an expert in using compost methods to correct metal contaminated sites. In Bowie, Maryland, for example, he found a high percentage of lead in the soils adjacent to houses painted with lead-based paint. To determine the effectiveness of compost in reducing lead bio-uptake in these soils, Chaney fed rats with contaminated soil and with contaminated soil mixed with compost. Both compost and soil trap lead, thereby reducing its bioavailability. Composted soil was more effective than untreated soil. In fact, rats exhibited no toxic effects from lead-contaminated soil mixed with compost, whereas they did exhibit toxic effects from soil alone.
In another study, Dr. Lee Daniels and P. D. Schroeder of the Virginia Polytechnic Institute, Blacksburg, Virginia, remediated a sterile site contaminated with sand and mud from a heavy metal mine.
The compost application revitalized the soil for agricultural use. 20 tons per acre were applied for Dr. Grano production and 120 tons / acre for peanuts.
Dr. Michael Cole, an expert in soil pollutant degradation, remediated a soil containing 3,000 parts per million (ppm) kl of dicamba herbicide to undetectable levels within 50 days. Cole mixed wood chips and mature compost into the soil to make the combined substrate, 10% (by volume) compost and wood chips, and 90% contaminated soil. According to Dr. Cole, dicamba eventually breaks down in the soil, but the process takes years instead of days. In addition to speeding up the Bioremediation process, using compost can also save money. The traditional method of remediation through landfilling and incineration can cost five times or more than composting technology. According to Dr. Cole, bioremediation by compost, more than any other soil cleaning technique, results in an enriched soil and leaves it in better condition than before it was contaminated.
Petroleum hydrocarbon contamination
At Seymour Johnson Air Force Base near Goldsboro, NC, the soil is contaminated as a result of frequent jet fuel spills and the excavation of underground fuel storage tanks. The base deals with a variety of petroleum contaminants, including gasoline, kerosene, fuel oil, jet fuel, hydraulic fluid, and motor oil.
In 1994, the base implemented a Bioremediation system using compost made from wood waste and turkey droppings. Previous remediation systems included lifting the contaminated soil and taking it to a brick maker, where it was incinerated at high temperatures. Compared to the cost of raising, incinerating and purchasing clean soil, Bioremediation with compost saved the base US $ 133,000 the first year. Using compost also resulted in quicker cleanup, since projects are completed in weeks rather than months.
The fungi in compost produce a substance that breaks down the hydrocarbons in oil, allowing the bacteria in the compost to metabolize it. A typical ratio consists of 75% contaminated soil, 20% compost, and 5% turkey manure. A power shovel mixes and churns the piles to keep them airy. After mixing, a vinyl nylon covers the batteries to protect them from wind and rain, and to maintain proper humidity and temperature for optimal microbial growth.
Storm water management
It is the excessive water not absorbed by the soil after heavy rains. Core on surfaces such as roads, parking lots, building roofs, fields and gardens. On their journey to larger bodies of water (lakes, streams, rivers) these waters can carry a wide range of potentially environmental pollutants, such as metals, oils and fats, pesticides and fertilizers. These types of pollutants pollute rural waters, damage recreational and commercial fishmongers, and degrade the beauty of waterways. This water, according to the environmental protection agency of the USA, must be treated before it is dumped into natural currents. To complete this, many municipalities and industries are turning to solutions that involve compost technologies instead of other traditional, much more expensive treatments. There is, for example, a filter system that uses compost and that retains more than 90% solids, 85% fats and oils and around 85% oils and fats.
Biofiltration vs. Bioremediation
Biofiltration involves physically separating particles based on their size.
Bioremediation, by contrast, implies a biochemical change, as the pollutants or pollutants are metabolized by microorganisms, and converted into harmless, stable constituents, such as carbon dioxide, water and salts.
* Translated and summarized by bioagro.
Source: EPA 530-f-97-042 (United States Environmental Protection Agency)