MANAGEMENT ASPECTS ON CIVIL CONSTRUCTION WASTE IN SÃO PAULO CITY - BRAZIL

Transcription

1 MANAGEMENT ASPECTS ON CIVIL CONSTRUCTION WASTE IN SÃO PAULO CITY - BRAZIL Cássia S. de Assis (1), Márcio J. Estefano de Oliveira (2) and Luiz Roberto Cottas (3) (1) Centro Universitário do Instituto Mauá de Tecnologia (CEUN-IMT), Brazil (2) Universidade Estadual Paulista (UNESP/UNITAU), Brazil (3) Universidade Estadual Paulista (UNESP), Brazil Abstract São Paulo is one of the biggest cities in the world, with a population of people, according to the 2000 Census. The amount of waste generated in construction and demolition of buildings makes their management a very complicated issue. The companies that perform the waste-removing services, the carters, are getting organized around the Selection and Transfer Areas (STA), as a mean to set a destination for the collected material. Recently, due to Resolução CONAMA-307, an specific resolution on construction an demolition residues on a national basis, established by the National Environment Council, which demands a management plan on every Brazilian municipality, with reutilization and recycling goals, STAs are being equipped with crusher and sieve, as a mean to provide the classificated material to be utilized as aggregate in pavement, as much as in non-structural concrete. In this paper, São Paulo city s Municipality requirements for operating of Selection and Transfer Area of Jaçanã (North Side of the city) are presented, showing the process of selection and segregation of the returnable materials in this STA. Lastly, it also presents the newly implanted system to crush concrete, mortar and ceramic material, to obtain aggregate utilized in pavement and non-structural concrete making. Keywords: Management of solid waste, environmental aspects, legislation in Brazil. 1. INTRODUCTION Recent surveys from São Paulo Municipality, Department of Urban Cleaning LIMPURB, indicate that m 3 of discharged material are produced in São Paulo city and collected by stationary carts every month. Non-official statistics, however, suggest that an even larger amount, of about m 3 of disposed material is generated per month [1]. Residue collected in São Paulo, according to Public Works Bureau and Urban Cleaning Department, is composed 37,06% by primary home waste, which comes from households and commercial activity, 4,93% by residue from pruning and sweeping, 2,02% by industrial waste, 0,37% by solid waste from health services, 18,08% by debris, 1,58% by general waste 275

2 (large volumes and dead animals) and 36,36% by secondary waste: leachate, refuse and transferred [2]. The citizens usual procedure, when they carry out a new construction, a reforming or a demolition is, at the end of a certain step or the works, depending on its size, to call a cart and put all the wastes in it. It can be observed, though, that the carts receive all kinds of refuses, from waste of the construction to pruning rejects and undesired objects, such as sofas and broken wardrobes. Composition of the material collected by the carts can differ depending on the region they are stationed and the kind of activity that demanded its use. Carts stationed in the city s central region usually receive the rejects of reforming, demolishing or reconstructing works, presenting large amounts of mortar, concrete, bricks and wall tiles residues. Carts installed in the outskirts area of the city receive big amounts of excavation soil, pruning and terrain cleaning material, besides rejects from new construction sites, including more recently used materials in Brazil s civil construction, such as plaster. Therefore, the great amount of waste generated by civil construction needs to have an adequate destination, since it is solid waste that can range to non-hazardous to hazardous, that contains different chemical substances depending on the construction method employed, on the works loss degree and the characteristics of the studied area s demolition residues. The diversity of the material collected by the carts, and the demands for recycling or disposing in the inert landfill, were the main reasons for the transporters to organize in associations, with the goal of creating Selection and Transfer Areas. The first association to become viable is located in Jaçanã disctrict, gathered 20 firms registered by the municipality and operates with a collected volume of m 3 per month. Other question that remains to be addressed is the ever increasing pressure that the public laws, through the CONAMA National Environment Council resolutions, have been making on the municipalities, with the goal of establishing responsible procedures in the managing and final disposing of urban solid residues. After July 2004, compliance to Resolução 307 will be demanded. In its 4 th article, it appoints that Civil construction waste shall not be disposed in sanitary landfills, non-controlled dumping areas, in slopes, water bodies, empty allotments and other inadequate destinations. Introducing these Environment Ministry new demands is a great challenge to municipal administrations and requires adequate models for the managing of urban solid waste. 2. THE SELECTION AND TRANSFER AREA Irregular disposal in São Paulo city is generating many problems, including the occupation of irregular dumping areas by shacks. Picture 1 shows one of these areas, located in the public way that coasts Tietê river. Picture 1 Shacks overseeing an irregular disposal area 276

3 When stationary carts are hired, many kinds of waste are collected, that need to be sorted out as to allow its reuse and eventual recycling. Picture 2 shows a stationary cart in a São Paulo street. Picture 2 Stationary carts seen in São Paulo streets Although it can vary, according to collectors reports, waste received in the carts collected by the debris transportation firms consist by the following materials: Table 1 Collected materials composition Inertes 65% Madeira 13% Plástico 8% Outros 14% Source: FERRAZ et al. [3] Residues from construction materials, such as mortars, concrete, bricks, tiles and soil fraction from excavations are considered as components of the inert fraction of the composition. Material comes in carts to the Selection and Transfer Area, and initially discharged in piles, as shown in Picture 3 Picture 3 Material discharged by the charts After the sorting process, some materials can be commercialized, as is the case with glass, which is presented in Picture 4, the case with the scrap shown in Picture 5, papers and 277

4 cardboards laid out in containers as Picture 6 shows, and plastics that are shown sorted out and packed in Picture 7 Picture 4 Glass Picture 5 Metal Scraps Picture 6 Papers and Cardboards Picture 7 Plastics These reusable materials are forwarded for reusing or recycling outside of the Selection and Transfer Area. Plastic is sold massively to recycling firms and already sums up 10 tons/month. Metal scraps are sold to companies that later forward them to metallurgical industries and represent 18 tons/month. Papers and cardboards sorted out in the Selection and Transfer Area are sold to scrap sellers, who resell them to the paper and cellulose industry and represent 4 tons/month. Glass sold to recycling companies appears with 1 ton/month. Picture 8 Inert Material Picture 9 - Garbage 278

5 Inside the area, the manual sorting of the material considered inert that stands in the pile is made as shown in Picture 8 and the non-reusable material, regarded as garbage, shown in Picture 9, must follow to the urban sanitary landfill. The fraction of inert material already sorted out in the deposit pile, at the early stages of the establishing of the Selection and Transfer Area was placed in tilting trucks with capacity to transport up to 15 m 3 of material. The truck left the STA to cross São Paulo city using the Tietê river coast road to reach its final destination, which was the inert landfill in Itaquera [4]. Recently, after the STA s official licensing, a system of crushing machines for aggregate production using recycled material was installed. Pictures 10 and 11 show the system that is already in operation. Picture 10 Crushing Machine Picture 11 Catterpilar and sieves system Material processed in this system has been presenting regular granulometry, as Pictures 12 and 13 show, which allows its use as coarse and fine aggregate in the production of nonstructural concrete and mortars. Picture 12 Coarse Aggregate Picture 13 Fine Aggregate Residue from the crushing process, shown in Picture 14, is being employed as subbase material used in the paving of streets and roads. 279

6 3. CONCLUSIONS Picture 14 Residue from the crushing process Correct final destination of the many components of debris implies in the minimization of environmental aggressions and collaborates in increasing the life quality of the community in an urban region so densely populated. Because of the distance and demands of the only official inerts landfill in São Paulo city, it was necessary to establish Selection and Transfer Areas to improve the working conditions of the collecting companies. The goals initially proposed by the debris transporters association, of organizing and giving assistance to the co-operating firms with the intention of giving a correct destination to the collected material, is getting good results and has helped to establish a debris recycler inside the STA itself. Each cart transported by a multi crane truck has a 4 m 3 capacity. The transfer to the bigger tilting trucks, with 15 m 3 capacity, has helped to diminish in more than 70% the amount of trucks transporting inert materials transiting in the Tietê river coast road going to the Itaquera landfill, lessening the pollution and improving the traffic conditions. With the installation of the debris crushing system inside the STA itself, there was another, and even greater, benefit with the recycling of the material and all of the advantages of its reuse. Another benefit that comes with the implantation of the Selection and Transfer Areas is the creation of new working posts for the poor communities around them, which supplies workers for the material s segregation and classification processes. The Resolução CONAMA 307 states that the adequate destination for construction and demolition residues procedures must take effect already in 2004 and, in the São Paulo City case, this goal is beginning to be reached from private enterprise and becoming a new business mode. REFERENCES [1] Assis, C.S. Modelo de Gerenciamento Integrado de Resíduos Sólidos Urbanos PhD Thesis IGCE/UNESP Rio Claro, Brazil, 120p., [2] São Paulo em Números Website acessado em 04/04/2002. [3] Ferraz, G.R.; Massuda, O.; Assis, C.S.; Oliveira, M.J.E.; Zamataro, R.S.I.; Pires,M.A.F.; Oliveira, M.C.B. & Amorim, A.S. Estações de classificação e transbordo na cidade de São Paulo. IV Seminário Desenvolvimento Sustentável e a Reciclagem na Construção Civil: Materiais Reciclados e suas Aplicações - IBRACON- CT 206. pp.75-86, São Paulo, Brazil, [4] De Baptisti, E. ; Hachen, F. Pedreira Itaquera : Metamorfose da Mineração. Uma breve história sobre a Pedreira de Itaquera. In: Anais do III Seminário Desenvolvimento Sustentável e a Reciclagem na Construção Civil: Práticas Recomendadas IBRACON São Paulo, Brazil,