Preliminary assessment of the metal contaminant potential of the leachate produced in a controlled sanitary landfill, Muribeca, Pernambuco, Brazil. * E. S. de Limal, J. F. T. Juca2, P. R. Bastes Leitel, V. L. A. de Melo2, E.J. de Barros Souto3 ldepartamento de Geologia e 2Departamento de Engenharia Civil da Universidade Federal de Pernambuco; 3Bolsista IC-CNPq *Parcialmentejkanciado pelo CNPq (Auxilio - PNEPPG) Abstract The Muribeca Sanitary Landfill is the biggest landfill in the Recife Metropolitan area. It occupies an area of 0.6km2 in the Jaboati%odos Guararapes County and receives a daily load of 2800tons of domestic, industrial and hospital solid wastes. The purpose of this work is a preliminary assessment of the contaminant potential load of the leachate produced in two of the cells of the landfill in relation to the soil, sediments and surface waters. In order to achieve this a systematic sampling was carried out during October of 2000. The leachate was sampled along the leachate drainage until its discharged into the Muribequinha stream and Jaboat50 river. The samples were submitted to chemical analyses by ICP/AES in order to determine Ag, Al, As, Ba, Cd, Cu, Fe, Mn, Ni, Pb and Zn. The results showed that, in the leachate, only Al, Fe and Mn were above the method detection limit (0,05mg din-3) in all analyzed samples. It was observed that the metal concentration decreased away fl-om the source, both in distance and in depth. The metal concentration in the leachate shows a 10-fold decrease for Al and Fe and a 20-fold decrease in Mn when it reaches Jaboatao River. Considering that the leachate flow during the year 2000 varied from 1.1 drn3s-l (January-dry season) to 31.76 dm3 S-l (June-rainy season) the contaminant load that eventually reached the Jaboatao river varied from 0,05-1.58 dm3 S-l (Mn), 3.3-95.28 dm3s-l(al) and 5,5-158.8 dm3s-l(fe).
454 Waste Management and the Ernirownent 1 Introduction The Muribeca Landfill is the biggest landfill site in the Recife Metropolitan area (RMA). Located in Jaboatao dos Guararapes Municipality, it occupies an area of 0.6kmz (Fig. 1), and receives a daily load of 2800tons of solid residues in the active cell. At the beginnig of operation, in 1985, the residues were deposited without any criteria directly on the ground. In 1994 the Empresa de Limpeza Urbana do Ret@ (EMLURB) began the recuperation and transformation process of the open-pit dumping site into a Sanitary Landfill, This process is still going on under the coordination of the Solid Wastes Research Group of the Civil Engineering Department, Federal University of Pemambuco. In 2001 the administration of the Muribeca Landfill changed from a single controlled administration (EMLURB) to a share administration (Recife and Jaboatao dos Guararapes Municipalities and State of Pemambuco), due to the fact that the landfill receives solid wastes tlom different municipalities in the RMA. Several studies and actions were and are still being executed in order to transform the open-pit dumping site in a Sanitary Landfill. As a consequence of these studies the area was divided into 8 cells (200x200m), each cell isolated by clay barriers in order to prevent or minimize the percolation of leachate to the soil and avoid its migration to the surface and groundwater. The lifetime of the landfill area was extended 8 years as a result of its transformation into a Sanitary Landfill. Nowadays the existing cells are basically filled up to their capacity and a new area, next to the existing landfill, is being licensed to receive the solid wastes produced in Recife and Jaboatao dos Guararapes Municipalities. 2 Objectives The main objective of the present study is a preliminary assessment of the metal contaminant potential of the leachate escaping the landfill in relation to surface water and soil. In order to accomplish this, a systematic sampling was done from the effluent point following the leachate course up to the Muribeca stream and the Jaboatao River (Fig. 1). These samples were submitted to analysis through atomic emission spectroscopy technique (ICP/AES) in order to determine the metals present in the leachate and surface water. 3 Material and methods In order to achieve the main objective leachate and water samples were collected according to the sampling scheme shown in figure 1. Samples were collected in October 2000 following the Standard ~ethods for Analyses of Water and Wastewaters [11 Procedures! Samples were Preserved with ~03 and digested following the method 3030 of the Standard Methods for the Analyses of Water and Wastewaters [11, and analyzedas soonas Possible byicp/aes. The solutions then obtained were analyzed for the determination of trace metals (Ag, Al, As, Ba, Cd, Cu, Fe, Mn, Ni, Pb and Zn) using an ICP/AES (TJA,
Waste Management and the En~ irownent 455 model IIUS/AP), with the following operational parameters: Burgener type concentric nebulizer; nebulizer pressure, 32 psi; cooling argon flow, 14dm3min- 1; auxilary argon flow, 1,5 dms rein-l; forward power, 1150kW; optical system, Echelle type. Quantitative analysis calibration curves were obtained using single element solutions containing 1000 mg din-s of Ag, Al, As, Ba, Cd, Cu, Fe, Mn, Ni, Pb and Zn. Method blanks and standards were analyzed in order to verifi contamination, accuracy and precision during analytical procedures. Method detection limit (MDL=0,05 mg din-s) was established as 3 times the standard deviation often blank analysis. 4 Results and discussion All samples were analysed for Ag, Al, As, Ba, Cd, Cu, Fe, Mn, Ni, Pb and Zn. Among them only Al, Fe and Mn were above the method detection limit in all samples (Tab. 1). The flow of the Ieachate produced in the landfill, during the year 2000, varied from 1,1 dms s-l during the dry season (January) to 31 dms s-l during the rainy season (June). Al, Fe and Mn (Fig. 2, 3 and 4) show a similar behavior in the leachate. Samples with higher concentration are located close to the discharge point in the landfill. The concentration of Al, Mn, and Fe decreases sharply at the sampling point number 4, reaching a 5-fold decrease for Fe (Fig. 2c). This decrease in the concentration of Al, Fe and Mn could be a consequence of a dilution effect caused by the flow a newer leachate that enter the main leachate stream at this point. From this point up to the confluence with the Muribequinha stream the concentration of Al, Fe and Mn remains practically constant. At this point the concentrations of Fe and Mn increase (200 /0and 20 /0,respectively) and Al stays at the same concentration level (Fig. 2, 3 and 4). This could be a consequence of the leachate discharge of several landfill cells, upstream the sampling site, into the Muribequinha stream, From this point up to the confluence with the Jaobatao river the concentration of Fe and Mn remains practically constant and Al shows a slight oscillation (Fig. 2). The other metals (Ag, Ba, Cr, Zn) present in the leachate do not show a regular behavior but show a decrease away from the source. Considering the leachate flow and its metal concentration one can estimate the contribution of the metal content from the landfill to the Jaboatao river. During the dry season the contaminant load would be: Mn, 0,05 mg s-l; Al, 3,3 mg s-l; Fe, 5,5 mg s-l. During the rainy season, the flow is much higher, and the metal load reaching the Jabaoatao river would be: Mn, 1,58 mg s-l; Al, mg s-l; Fe, 158,8 mg s-l. These values do not pose an immediate threat to the Jaboatao River. However, considering the cumulative effect and the fact that the metal load will eventually reaches the Jaboatao estuary, a more detailed and long term monitoring program should be undertaken,
456 Waste Management and the En~irownent ~=kqb.., \,/-j L P> -. ---------- Recife --------- b --- L-./ - 1. 2 Samplm* pant ~~1.mcifillarea 10(1 o )0[1 x) 300 400, ($ Figure 1. Location and situation map of the Muribeca Landfill, Recife Metropolitan Area, Brazil. Table 1. Metals present in the Ieachate from the Muribeca Sanitary Landfill Element Ag Al Ba Cr Fe Mn Zn Sample 1 0,09 23,00 n.d. 0,34 57,00 1,22 0,08 Sample 2 0,13 38,90 0,10 0,80 42,24 0,73 0,10 Sample 3 0,15 39,40 0,14 0,87 54,80 1,22 0,12 Sample 4 0,07 18,23 0,05 0,63 11,02 0,45 0,06 Sample 5 n,d. 13,60 0,05 0,86 11,20 0,51 0,98 Sample 6 0,06 17,73 0,06 0,79 11,13 0,49 0,09 Sample 7 0,06 15,74 0,05 1,73 36,50 0,58 0,06 Sample 8 n.d. 7,90 n.d. 0,51 6,68 0,05 0,08 Sample 9 0,05 10,84 n.d. 0,05 5,57 0,05 n.d. Sample 10 n.d. 2,98 n,d. 0,68 5,08 0,06 0,05 Sample 11 0,05 10,20 n.d. n.d. 5,05 0,05 0,06 Samples 1-6: Lechate; 7 9 Muribeca Stream; 10-11 Jaboatao River.
Waste Management and the En~ irownent 457 + g g. 30. 40-35- 25-20- 15-10- 5 I 5 >.-. 0 1 2 3 4 5 6 7 8 9 10 11 12 Sample Figure 2. Al distribution fi-omthe effluent point in Muribeca landfill up to the Jaboat50 River. 1,4 0 1 2 3 4 5 6 7 8 9 10 11 12 Sample Figure 3. Mn distribution from the effluent point in the Muribeca landfill up to the Jaboat50 River.
458 Waste Management and the En~irownent 12 0 1 2 34 5 6 7 8 9 10 11 12 Sample Figure 4. Fe distribution from the effluent point in the Muribeca landfill up to the Jaboat50 River. References [1] APHAIAWWAIWEF., Standard Methods for the Examination of Water and Wastewater. 18thEdition. Washington, DC.1992.