The composting of solid urban waste generates organic compost for agriculture usage, fulfilling the fundamental principles for sustained development, which are: reducing environmental impacts, such as diminishing waste and increasing recyclability (Inácio; Miller, 2009)
Besides the benefit to the soils for agricultural usage, composting has many positive environmental effects which are the reduction of hydric resource pollution, increasing lifespan of landfills and diminishing emissions of methane from urban residues. Therefore, composting contributes greatly as an environmental service.
By microorganisms’ actions, invertebrates beings and small vertebrates, decomposing of organic residues happens when in ideal conditions. However, when it is accumulated in disorderly way, has a big damaging potential to the environment and to the human health. This is common fact in irregular waste deposits and in urban areas where these residues attracts diseases transmitters. Composting is characterized by the predominance of thermopiles microorganisms that generate average temperature of 60oC. Such high temperatures are a positive towards eliminating human pathologies and mosquito larvae.
The organic residues from domestic waste, corresponds around 45% to 60% of its total weight. When it is thrown away at open waste deposits it generates large quantities of CHORUME (bio fertilizer) and methane, attracting vectors of various diseases (INACIO; MILLER, 2009)
At these open waste deposits the organic waste is suffering from the influence of an anaerobic environment and thus goes through anaerobic fermentation and decomposition, generating different pollutant compounds that come out as a liquid fluent that must be collected and treated before being in contact with environment. The methane gas, generated through anaerobiosis, is 21 times more potent than carbon dioxide for the greenhouse effect (INACIO; MILLER, 2009).
Composting also diminishes heavy metals pollutant potential that are present at organic residues. That happens due to the humic substances that make chelates and therefore absorbs heavier metals, avoiding them from affecting plants and leaching. (INACIO; MILLER, 2009)
The temperatures reached by thermophilic composting (55oC – 85oC), during material decomposition, promotes the absence of pathogenic agents to the final compost to be used as fertilizer (INACIO; MILLER, 2009)
For demanding the community participation in separating and selecting the organic residues at its origin, meaning at homes, schools, restaurants and agro industries, etc. Composting promotes the empowerment of the population regarding the environmental pollution of one’s hometown.
The original goal of “organicity” was to widen the collection of organic residues from public schools and commercial places in Guaxupe-MG so that we could use it for composting (making use of static lines of passive aeration) and we would then promote environmental education where we planned to collect the organic waste from the mentioned places. As the time went by, the project became stronger and by the end of 2017 we made a partnership with the Regional Coffee Cooperative (Cooxupé), where we currently collect about 30ton of monthly waste.
The “Organicity Project” has been in place since March 2016. We make weekly reports about the activities. Based on these reports the project writes its materials and methods.
Organic recycling from this project deals with residues being separated at its origin, not with mixed common residues that are separated at “recycling plants”. Meaning that Cooxupe takes on the responsibility of selecting and separating its own organic waste so that we can then collect it.
For the correct separation and deep understanding of the importance of organic recycling we had various talks about the matter. At Tulha Farm, where the composting occurs, we host meetings with students from local public schools where there is a presentation of a play called “Caipora” as well as practical and theoretical explanation about composting. The play “Caipora” was created by the Mask Group from Guaranesia Town, thinking of the rural environment as a background for the tale being told.
Visiting the farm is available upon any school request.
At Cooxupe, one of the places we get some waste from, we have meetings with local workers/contributors where we talk about the environmental importance of recycling the organic part from solid urban waste and its practice.
Each participating school or commercial place (restaurants and so on) have their own special bin for placing the organic waste they generate. These bins have a sealing system that is adequate for avoiding bad smells and insect attraction. Each bin volume is 60 L and there may be more than one at each collecting place. The picking up of the residues that is generated by the various participants occurs every Friday, when we swap full bins by empty and washed bins.
Examples of residues:
-Left overs from rural production, vegetal leaves or barks of grains, non-tradable fruits, manures, etc.
-Organic agro industrial waste, such as barks and straws.
-Food scrap from restaurants and distribution centers.
The composting method used is known as UFSC method, as it was developed at Federal University of Santa Catarina, This method works by the creation of static lines of passive aeration.
This system is based on the decomposition through aerobic and thermophillic microorganisms, or in other words, microorganisms that need O2 and generate heat through its decomposition process. The generated heat eliminates pathogenic organisms.
Different from other aerobic composting methods, the static lines of passive aeration do not need mechanical movements for its aeration, diminishing the costs involved in the process.
The aeration of USFC method is promoted by the lines structure, made of alternated layers of urban organic waste and porous materials of high Carbon/ Nitrogen ratio, such as sawdust, coffee bark, etc.
The decomposing made by microorganisms uses the oxygen from the atmosphere to decompose the carbon molecules from organic waste, releasing carbon dioxide, water and generating heat, and its final product is a stable material of dark color and pleasant smell (INÁCIO; MILLER, 2009).
Our current production of organic recycled material is at around 4.5T weekly. A Ford/1000 truck year 1989, run on diesel, provided by our farm collects the waste. Its average diesel consumption is 4km/L, in a rout of 30kms, which goes from the Tulha Farm through Guaxupe City and then returns to the farm; the quantity of diesel used is 7.5 L each collecting time. Besides this truck, Cooxupe delivers to us its solid residues through a hired truck service of their own.