Concerns about the problem of solid waste in Brazil is increasing over time, public policies for disposal are moving slowly and some attitudes have already been taken, such as the creation of the National Policy for Solid Waste in 2012, and its determination for the termination of dumps throughout the country by 2021 (deadline has already been extended twice). Dumps are an inadequate form of final disposal of solid waste, because they do not have any environmental control to reduce odors, the attract of disease vectors which threaten public health, to prevent contamination of soil and water bodies, as well as avoid greenhouse gas emissions. The most appropriate destination today is the landfills, which must be regularized and appropriate to reduce all these impacts mentioned above. However, even though landfills are a solution with minor impact, they also have certain limits, and their useful life is decreasing each day due to a large amount of waste generated every day.
According to the Brazilian Association of Public Cleaning Companies and Special Waste (ABRELPE), in 2018 the country has produced around 216,629 tons of solid urban waste per day. It includes the recyclables, organic material, and refuse, and according to the National Policy for Solid Waste, the recyclables should be sorted and sent for recycling, the organic materials sent for composting, and only the refuse sent to landfills. In order for such segregation to take place, a joint effort of the public power, private sector, and the population itself, which is responsible for the first segregation, at the beginning of the generation of domestic waste, is necessary.
Looking from a global perspective, according to the United Nations Environmental Program and the International Solid Waste Association, 2015 solid waste generation was between 7 and 10 billion tons, with approximately 2 billion tons being urban solid waste (24%). According to the same report, despite advances in the area, about 2 to 3 billion people in the world, usually in developing countries, do not have access to a regular service of collection and/or controlled disposal of solid waste. This reflects the scale of the problem, which is no longer just an environmental issue but becomes a priority public health issue, requiring multiple efforts and coordinated actions in order to solve it.
Besides, companies and industries have the obligation to collect the waste generated with the consumption of their products, such as glass, plastic and etc., and return them to their production chain to be reused, thus implementing reverse logistics. However, what few people know is that the organic material destined for the landfill next to the refuse (material that cannot be used in any way) is actually a type of waste that can be used to generate fertilizer and organic compost through composting.
Organic waste consists basically of animal or plant remains discarded from human activities. They can have several origins, such as domestic or urban, agricultural or industrial, basic sanitation (sludge from wastewater treatment plants), among others. They are materials that, in balanced natural environments, spontaneously degrade and recycle the nutrients in natural processes. Therefore, it is necessary to adopt adequate methods for the management and treatment of these large volumes of waste, so that the organic matter present is stabilized and can fulfill its natural role of fertilizing the soil.
According to the national waste characterization published in the preliminary version of the National Solid Waste Plan, organic waste corresponds to more than 50% of the total urban solid waste generated in Brazil. Added to the organic waste from agroforestry and industrial activities, the data from the National Solid Waste Plan indicates that there is an annual generation of 800 million tons of organic waste.
Although, currently, less than 2% of urban solid waste is destined for composting. Taking advantage of this enormous potential of nutrients to return fertility to Brazilian soils is among the greatest challenges for the implementation of the National Policy on Solid Waste.
Organic correction of soils with animal waste and plant residues has been practiced since soils began to be mobilized for plantation production, and has traditionally been the main means of restoring the balance of nutrients in the soil. It is likely that the practice of composting, which emerged with the first agricultural crops made by man, there are some records that indicate that in China there were compost heaps more than two thousand years ago.
Over the following decades, composting was studied and improved in a scientific way, becoming a technology capable of solving agricultural problems, such as the recovery of degraded soils, disease control as well as solving environmental issues related to the treatment of urban solid waste. Until the end of the 1960’s, composting was considered an attractive process for urban solid waste management. The interest in composting resulted in the hope of selling the finished product as an agricultural input and making some profit. However, in the 1970s and 1980s, composting in developed countries lost its popularity as a method of managing municipal waste, mainly because the quality of the waste became increasingly inadequate for the composting process and also because there was no market for the finished product.
Composting, then, is a way of recycling organic waste, anaerobic, and totally controlled process of biodegradation of organic matter, i.e. the decomposition of organic waste by Californian microorganisms or earthworms, and as a result, there is the organic fertilizer, or organic compound, rich in nutrients.
The Ministry of Environment defines composting as:
“Composting is a way to recover nutrients from organic waste and bring them back into the natural cycle, enriching the soil for agriculture or gardening. Furthermore, it is a way to reduce the volume of garbage produced by society, destining correctly a waste that would accumulate in dumps and landfills generating bad smell and the release of methane gas and slurry (a liquid that contaminates soil and water)”. “
According to Eclo, organic compost, image 1, is the product of composting that grants good fertility to soils since it enriches soils lacking in nutrients; it helps in soil aeration, water retention and helps in the containment of erosion caused by rains; also, organic compost increases the capacity of plants to absorb nutrients.
Composting can be aerobic or anaerobic, depending on the presence or not of oxygen in the process. Anaerobic composting is performed by microorganisms that can live in environments without the presence of oxygen; it occurs at low temperatures, with strong odor exhalation and it takes longer for organic matter to stabilize. In aerobic composting, decomposition is performed by microorganisms that live only in the presence of oxygen or by worms. In the first case, the temperature can reach up to 70°C, the odors emitted are not aggressive and the decomposition is faster.
Besides the organic compound, when the composting is anaerobic, we have the formation of the biofertilizer (image 2). The biofertilizer is a liquid organic fertilizer, a by-product of composting. When diluted in water in the most usual proportion of 1/10 (one-part biofertilizer to 10 parts water) it is excellent for improving soil fertility since it has many nutrients; produces healthier food with less impact on the environment; improves soil structure, avoiding erosion; has a lower cost when compared to chemical fertilizers; serves as a natural repellent, ensuring resistance to plants to attack by pests. It can be used both on the soil and on plant leaves.
Operation and Benefits of the System
It is the composting method performed by Californian worms of European origin, known for its efficiency in the composting process. The result of this composting is the earthworm humus, which acts to improve the physical, chemical, and biological characteristics of the soil. In addition, a liquid is also generated that is an excellent biofertilizer, but it must be diluted in water in a proportion of 1 to 10 so that it is in adequate concentration to be placed in the soil, otherwise it may actually become a soil contaminant, as mentioned above.
The worm cell (or compost), illustration 3, must be aerated, i.e. have an entrance for oxygen. It should line the base of the board with what is called a “bed”. A suitable bed for your vermicompostor should consist of one or more of the following: newspaper strips, paper, cardboard, dry leaves, and earth. Avoid paper with inks because heavy metals are harmful to worms and contaminate the compound. You should tear, cut, and moisten the different materials well to create a suitable environment for the worms.
Place the worms over the vermicompostor bed. You can tear a few more sheets of newspaper into strips 1 to 2 cm wide. Dip the strips in water to moisten them slightly and then wrap them without compressing too much. Place the food, preferably cut into small pieces, to facilitate decomposition. Leave the box of worms to rest, without adding food for 1 week, so that the worms can get used to the new environment and start decomposing the food remains.
After the first week, add food to the box 3 or 4 times a month: move the bed a little away and spread the leftovers; cover again with the bed. Carefully invert the material with a rake.
The place of the composter needs to be airy, cool, and not sunny, or the worms run away due to the heat. To collect the humus, put the earthworm in the sun for a few minutes, for the worms to go down, and remove the top of the humus. The composting process lasts about 90 days.
Although the feeding of different species of worms may vary, Table 1 and Table 2 in sequence shown in more detail, respectively, the most and least suitable foods for compost supply:
Some points to be stressed are that the control of this type of composting is more complicated, since it requires optimal conditions for the degradation of residues by Californians.
Some downsides of this process are not being able to put citrus or cooked food, bones, cheese and processed. You cannot put the compost in a sunny and warm environment. If done in the wrong way, it can generate flies and larvae.
Domestic compost heap
Compostagem com microrganismos
In the composting by microorganisms, there is no presence of worms. The whole process is carried out by them and an organic compost capable of improving soil quality is also obtained. As there are no worms to open paths for oxygen this type and composting requires greater care in aeration.
The first step is to add a layer of dry leaves to the bottom and sides of the compost, then a layer of fertilizer is placed and then the organic waste (next to the dry leaves and/or sawdust) and finally a layer of just dry leaves to cover the waste. The dry leaves on the bottom and cover are to prevent access by animals, insects, and vectors.
The compost heap must then be turned over weekly for three months to ensure oxygenation and aerobic process, otherwise, odor-causing substances will be generated during the process. In the last month when composting is in its final stage of ripening the compost heap must only be turned over once. After this period of four months, the compost is ready, just sieved, and can already be used. The sieved material can also be reused and used as compost for the next compost heap, starting a new composting cycle.
Engineers Without Borders’ work
Engineers Without Borders – Brazil has several network centers that use the composting process to bring gains to the community. The projects are mainly carried out in schools and neighborhoods together with the community’s vegetable garden project, thus bringing quality organic food to the beneficiaries, in addition to raising awareness of the population in favor of the environment and more sustainable habits.
The Engineers Without Borders network believes that composting is a way to align with the UN’s Sustainable Development Goals (SDGs). Through composting it is possible to achieve targets set for Goals 11 and 12 that are, respectively, to make cities and human settlements inclusive, safe, resilient, and sustainable and to ensure sustainable production and consumption patterns. Furthermore, when composting is done together with the organic garden project it is still possible to achieve some targets of Goal 2: ending hunger, achieving food security and improving nutrition, and promoting sustainable agriculture.
Due to the fact that the compost heap is a simple project with great returns for the community, and even for individual use, several ESF-Brazil chapters have already executed this project, including the chapters in Florianópolis (SC), Ilha Solteira (SP), João Monlevade (MG), Joinville (SC), Tupã (SP), Juiz de Fora (MG) and Lorena (SP).
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Each chapter sought to address the issue of composting in the most appropriate way for the place where it would be inserted. Some of them carried out projects in schools with limited spaces, so they prioritized composting with Californian worms made with buckets and plastic containers in order to compact the experience and bring the compost to these schools. Projects in communities or schools with greater space availability were able to make the compost with compost heap and delimited with wooden boxes, some used the vermicomposting method and others preferred the use of microorganisms.
It is important to think that when choosing the type of compost heap, one should also think about whether the community will be engaged in turning it, adding dry leaves/sawdust, and always feeding the compost bowl with the correct organic material. That is why when implementing this kind of continuous and long-lasting project having contact with the beneficiaries in the initial moments is essential, so it is possible to follow the development of composting if people are adhering to the separation of the organic material and are favoring the aeration of the compost. Once this becomes a habit of the local community or school then one can let the project start walking with its own legs from the initiative of the residents, students, or teachers.
Be yourself the change you want to see in the world: Eclo – Urban Composting
Eclo is an urban composting company that operates in the city of Juiz de Fora, it arose in the scene of the need for two women to want to be a part of change in the world. Unhappy with the situation of garbage, especially organic garbage that there was no proper treatment, Eclo was created.
The company serves, through individual and corporate plans, with weekly or biweekly collections. Besides these fronts, there is the voluntary front, which is in the process of formation, with the objective of bringing composting to people and places that want or need it.
Image 8 shows the process of composting done by them, it is done with microorganisms in static heaps with convectional aeration.
Victória Abrahão Fonseca e Silva
Co-founder of Eclo
Technical Vice-President – ESF-BR 2019 Board
Anna Beatriz Bergo