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There is an acknowledged need for an environmentally friendly method of green waste disposal on the Isle of Man. Figures from D.O.L.G.E. (W.O.M.U.) indicate that the local community generates approximately 260 000 tonnes of waste that is presently disposed of at the landfill or to the incinerator. Approximately 20% of this is green waste and is suitable for disposal by composting.
We understand that the current landfill site at Wrights Pit is nearing the end of its ability to accept shredded green waste for topping off purposes. After this the green waste is to be incinerated at a cost of £100.00 per tonne. We are also led to believe that the Southern Amenity sites facility for accepting green waste is approaching an end as the area where the composted waste was spread has now been fully landscaped.
Our intended method of green waste disposal is the 'windrow' composting system.
The product of the composting process will be used, as a soil enhancer on site and any surplus will be sold for agricultural or local authority use and would also be suitable for use in organic farming.
The proposed location for this application is on agricultural land well away from residential areas. It is centrally located and is convenient for the main arterial routes.
We anticipate 5 HGV movements to the site per week as well as a number of light goods vehicles.
Surface water runoff is to be collected on site and re-used in the composting process.
We envisage that a portacabin would be needed on site so that accurate records of vehicles attending the site and waste movements can be accurately recorded. We would ask that permission be granted for a period of five years for the location of this temporary building.
There is existing vehicular access to the site. However we wish to move the existing gateway in an easterly direction by some 4 metres. This is to comply with visibility requirements and to ensure safe access and egress from the site for our own agricultural machinery and visiting vehicles.
The chosen site has been provisionally passed subject to obtaining planning permission as suitable by Environmental Protection Section of D.O.L.G.E.
Composting is the transformation of organic material (plant matter) through decomposition into a soil-like material called compost. Invertebrates (insects and earthworms), and micro organisms (bacteria and fungi) help in transforming the material into compost. Composting is a natural form of recycling, which continually occurs in nature.
An ancient practice, composting is mentioned in the Bible several times and can be traced to Marcus Cato, a farmer and scientist who lived in Rome 2,000 years ago. Cato viewed compost as the fundamental soil enhancer, essential for maintaining fertile and productive agricultural land. He stated that all food and animal wastes should be composted before being added to the soil. By the 19th century in America, most farmers and agricultural writers knew about composting.
Today there are several different reasons why composting remains an invaluable practice. Yard and food wastes make up approximately 30% of the waste stream in the United States. Composting most of these waste streams would reduce the amount of Municipal Solid Waste (MSW) requiring disposal by almost one fourth, while at the same time provide a nutrient-rich soil amendment. Compost added to gardens improves soil structure, texture, aeration, and water retention. When mixed with compost, clay soils are lightened, and sandy soils retain water better. Mixing compost with soil also contributes to erosion control, soil fertility, proper pH balance, and healthy root development in plants.
The standard means of disposal for most yard and food waste include land filling and incineration. These practices are not as environmentally or economically sound as composting. Yard waste which is land filled breaks down very slowly due to the lack of oxygen. As it decomposes, it produces methane gas and acidic leachate, which both cause environmental problems.
Land filling organic wastes, also takes up landfill space needed for other wastes. Incinerating moist organic waste is inefficient and results in poor combustion, which disrupts the energy generation of the facility and increases the pollutants that need to be removed by the pollution-control devices. Composting these wastes is a more effective and usually less expensive means of managing organic wastes. It can be done successfully on either a large or small scale, but the technique and equipment used differ.
Decomposition occurs naturally anywhere plants grow. When a plant dies, its remains are attacked by micro organisms and invertebrates in the soil, and it is decomposed to humus. This is how nutrients are recycled in an ecosystem. This natural decomposition can be encouraged by creating ideal conditions. The micro organisms and invertebrates fundamental to the composting process require oxygen and water to successfully decompose the material. The end products of the process are soil-enriching compost, carbon dioxide, water, and heat.
Composting is a dynamic process which will occur quickly or slowly, depending on the process used and the skill with which it is executed. A neglected pile of organic waste will inevitably decompose, but slowly. This has been referred to as "passive composting," because little maintenance is performed. Fast or "active" composting can be completed in two to six weeks. This method requires three key activities; 1) "aeration," by turning the compost pile, 2) moisture, and 3) the proper carbon to nitrogen (C: N) ratio. Attention to these elements will raise the temperature to around $130 = -140 =$, and ensure rapid decomposition.
The success with which the organic substances are composted depends on the organic material and the decomposer organisms involved. Some organic materials are broken down more easily than others. Different decomposers thrive on different materials as well as at different temperature ranges. Some microbes
require oxygen, and others do not; those that require oxygen are preferable for composting.
A more diverse microbial community makes for a more efficient composting process. If the environment in the compost pile becomes inhospitable to a particular type of decomposer, it will die, become dormant, or move to a different part of the compost pile. The transforming conditions of the compost pile create a continually evolving ecosystem inside the pile.
All organic material will eventually decompose. The speed at which it decomposes depends on these factors:
Carbon and nitrogen are the two fundamental elements in composting, and their ratio (C: N) is significant. The bacteria and fungi in compost digest or "oxidize" carbon as an energy source and ingest nitrogen for protein synthesis. Carbon can be considered the "food" and nitrogen the digestive enzymes.
The bulk of the organic matter should be carbon with just enough nitrogen to aid the decomposition process. The ratio should be roughly 30 parts carbon to 1 part nitrogen (30:1) by weight. Adding 3-4 pounds of nitrogen material for every 100 pounds of carbon should be satisfactory for efficient and rapid composting. The composting process slows if there is not enough nitrogen, and too much nitrogen may cause the generation of ammonia gas which can create unpleasant odours. Leaves are a good source of carbon; fresh grass, manures and blood meal are sources of nitrogen.
Decomposition by micro organisms in the compost pile takes place when the particle surfaces are in contact with air. Increasing the surface area of the material to be composted can be done by chopping, shredding, mowing, or breaking up the material. The increased surface area means that the micro organisms are able to digest more material, multiply more quickly, and generate more heat. It is not necessary to increase the surface area when composting, but doing so speeds up the process. Insects and earthworms also break down materials into smaller particles that bacteria and fungi can digest.
The decomposition occurring in the compost pile takes up all the available oxygen. Aeration is the replacement of oxygen to the centre of the compost pile where it is lacking. Efficient decomposition can only occur if sufficient oxygen is present. This is called aerobic decomposition. It can happen naturally by wind, or when air warmed by the compost process rises through the pile and causes fresh air to be drawn in from the surroundings. Composting systems or structures should incorporate adequate ventilation.
Turning the compost pile is an effective means of adding oxygen and brings newly added material into contact with microbes. It can be done with a pitchfork or a shovel, or a special tool called an "aerator," designed specifically for that purpose. If the compost pile is not aerated, it may produce an odour symptomatic of anaerobic decomposition.
Micro organisms can only use organic molecules if they are dissolved in water, so the compost pile should have a moisture content of 40-60 percent. If the moisture content falls below 40 percent the microbial activity will slow down or become dormant. If the moisture content exceeds 60 percent, aeration is hindered, nutrients are leached out, decomposition slows, and the odour from anaerobic decomposition is emitted. The "squeeze test" is a good way to determine the moisture content of the composting materials. Squeezing a handful of material should have the moisture content of a well wrung sponge. A pile that is too wet can be turned or can be corrected by adding dry materials.
Micro organisms generate heat as they decompose organic material. A compost pile with temperatures between 90° and 140°F (32°-60°C) is composting efficiently. Temperatures higher than 140°F (60°C) inhibit the activity of many of the most important and active organisms in the pile. Given the high temperatures required for rapid composting, the process will inevitably slow during the winter months in cold climates. Compost piles often steam in cold weather. Some micro organisms like cool temperatures and will continue the decomposition process, though at a slower pace.
Some municipalities collect yard waste at the kerbside similar to the way recyclables are collected. It is taken to a central location and formed into windrows, triangular-shaped rows from 5 to 8 feet high and as long as necessary. Turning for aeration is done about once a month using a front-end loader or other type of heavy equipment made specifically for that purpose. The temperature and moisture are checked twice a week. The finished compost may be sold, given away, or used by the municipality in public works projects. Backyard composting eliminates the environmental and economic costs of the heavy equipment used to bring yard waste to a composting site and turn the windrows.
J Gilbert
The UK composting industry has come a long way from its humble origins a decade or so ago, with The Composting Association's annual surveys indicating that the overall picture is one of continued expansion. The latest survey (carried out last year by the Open University on behalf of the Association) suggested that composting increased by approximately 23% between 1998 and '99. Based upon respondents' returns and trends over recent years, it is anticipated that the UK was on course to compost one million tonnes of material during 2000 (see Figure 1).
Figure 1 - Mass of materials composted in the UK {{image:368370}} Source: Slater & Frederickson (2001)
As you can clearly see the Isle of Man has fallen a long way behind the U.K in its handling of green waste. This needs to be addressed now and not in the future.
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