Brazil: Controlled Composting In Developing Countries
For more than six years, pilot and large-scale composting experiments have been done at the University of Vicosa in Vicosa, Brazil. We focused on low cost technologies, forced aeration techniques, vector and leachate control, process monitoring, staff training, and technical assistance to farms and city councils. It seems that an unwritten law for solid waste management for developing countries consists of collection and landfilling. But objections to dumping practices have increased strongly and have caused a movement to new, environmentally safe solutions.
Our basic strategy has focused on building support and communications with four target groups: Local community; Federal government and institutions; Local council and authorities; and Local associations and nongovernmental organizations. Audits of the solid waste produced in developing countries have shown that 50 to 70 percent of the refuse mass is organic; 5 to 15 percent is recyclable material (glass, metal, etc.); and 30 to 40 percent is inert rejects. The composting research was significantly assisted by our agreement with the University of Leeds, which was supported by the United Kingdom Overseas Development Administration.
The first facility to implement our recycling/composting concept (with minimum landfilling of rejects) was in the Olinda/Peixinhos region of northeast Brazil. The plant had the following modules: Refuse reception (using a small sloping concrete apron); Concrete table for manual sorting (which can be made from wood); Compost pads — one for the active phase, and the other for maturation and storage; and A building for storing recycled material, tools and equipment, administration offices and toilets.
This type of plant has a typical capacity of 15 metric tons/day. Construction materials can consist of bricks, cement blocks, soil cement and other locally made products. Ease of construction allows the plant to be completed in only 50 to 60 days using local labor.
Case Study In Coimbra, Brazil
This case study describes a low cost, composting/recycling plant built in the Brazilian city of Coimbra, Minas Gerais State — 7,300 inhabitants in which commerce and agriculture are the main economic activities. The city is governed by a mayor, deputy mayor and eight town councilors.
The solid waste produced consists of residential and commercial waste, road sweepings, yard trimmings, residuals produced by pharmacies and one health center. There are no industries, and construction debris is generally recycled. Prior to the plant being built, refuse was collected by handcart and animal cart and was disposed of in an open dump where pigs fed on the garbage. The pigs’ meat was sold in the local market. On average, eight people lived as scavengers on this dump — recycling cans, paper, glass, plastics, etc. Their living conditions were extremely poor.
The dump contaminated a small river as a result of constant leachate percolation. This stream was used by animals for drinking and to irrigate crops. It was assumed that the groundwater was also contaminated since this site had been used as an open dump for the previous six years. The city produces an average of three metric tons of refuse/day.
The strategy used to bring the council and the community together to build the plant was managed by the University of Vicosa and was similar to that used in five previous projects. It consisted principally of the following steps: Convince the mayor of the importance of the project and all the problems associated with the current practices; Start a program of meetings in the city talking about the problems and identifying the local leaders, community associations, NGOs, etc.; and Sign an agreement between the University and the city council that details the responsibility of each participant and includes the timetable.
In this document, the city council provides the work force, the land and the materials. The University provides all the technical assistance for project, plans, studies, surveys, etc., and the general coordination. The local community organization was also involved in the coordination, together with the University, specifically relating to community mobilization and purchasing of materials. The council applied to the state government for funds to support the project.
Operations At Composting Facility
The plant in Coimbra employs eight people — five of whom used to be scavengers on the open dump (thus fulfilling an important aspect of the project’s philosophy). It was built with a maximum capacity of 15 metric tpd and is working now with an average of 3 metric tpd. From this amount of refuse, the council is selling 4 metric tons of recycled materials, producing 12.3 metric tons of matured compost, and burying 4.6 metric tons of rejects per month.
Rejects are buried in an appropriate area using a trench system. The pharmacy waste and the waste produced in the health center are disposed of in the same place. Waste is now collected using 12 handcarts (150kg each) and three animal carts with a capacity of 450kg each.
Collection service has been made on a door-to-door basis once a day. Experience from the other projects shows that the implementation of a selective collection system is important to enhance the flexibility and quality of the composting plant. This will be implemented in the next phase of the project, after the community and the work team get used to the new system. The city is now clean, and the local community can see benefits gained in terms of environmental quality and public heath.
Why Compost In Developing Regions?
In the Minas Gerais state, as in other states in Brazil, we find the following picture: More than 600 municipalities have a population less than 20,000; Typical organic content in residential solid waste is around 68 percent; agricultural output is reduced due to low soil fertility; health problems from solid waste contamination; and unemployment leading to various social crises. However, the practical field work done by the University of Vicosa has proved that the integrated solid waste management program is able to minimize and, in the near future, to overcome many of these problems.