Determination of the suitable size of tire chips for landfill leachate treatment

Md. Akbar Hossain, Mostafa Warith, Jinyuan Liu, Bibek Mondal

Dans les comptes rendus d’articles de la conférence: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Geoenvironmental Engineering

ABSTRACT: Five bio-filters were built in the laboratory. Four of which were packed with different sizes (mixed, large, medium and small) of tire chips and the remaining one was packed with tire crumbs to determine the suitable size of tire chips for landfill leachate treatment. The overall results demonstrated that highest removal of BOD (55-56%), COD (93-100%), NH3-N (78-80%), TS (42-45%) and TSS (98-100%) were attained in small (10-20 mm) and medium (20-40 mm) size tire chips. The bio-film, 25 g/kg or 1.1 kg/m2 surface area of tire chips, was equally attached onto both the medium and small sizes tire chips. Indeed, minimal clogging effect, which was observed in these two media did not considerably affect the hydraulic conductivity. Based on the findings, 10-40 mm size (defined as small and medium) tire chips can be used as packing media in bio-filter for secondary treatment of landfill leachate.

RÉSUMÉ: Cinq bio-filtres ont été construits dans des états de laboratoire. Quatre dont ont été emballés avec différentes tailles morceaux (mélangés, grands, moyens et petits) de pneu et autres ont été emballés avec des miettes de pneu pour déterminer les tailles appropriées des morceaux de pneu pour le traitement de lixiviat de remblai. Les résultats globaux ont démontré que le déplacement le plus élevé de la DBO (55-56%), la MORUE (93-100%), NH3-N (78-80%), les SOLIDES TOTAUX (42-45%) et les SOLIDES SOLUBLES TOTAUX (98-100%) ont été atteints dans petit (10-20 millimètres) et les tailles du milieu (20-40 millimètres) fatiguent des morceaux. Le bio-film, la superficie 25 g/kg ou 1.1 kg/m2 du pneu ébrèche, a été joint également à l'un ou l'autre milieu et les petites tailles fatiguent des morceaux. En outre, l'effet obstruant minimal était dans ces deux médias, qui n'ont pas affecté de manière significative la conductivité hydraulique. On le conclut que des morceaux de pneu de tailles de 15-40 millimètres (définies comme petites et moyennes) peuvent être employés comme médias d'emballage dans le bio-filtre pour le traitement secondaire du lixiviat de remblai. 1 INTRODCTION In Canada, huge generation of undesirable scrap tires is a growing issue of health risk and harm to the environment because tire materials are not biodegradable. The scrap tire stockpiles provide the congenial breeding ground for mosquitoes, rodents, snakes, and west Nile viruses thereby become a potential source for health hazards (Mondal, 2006). Not only have that, incineration of scrap tires caused the hazardous pollution in air (BP-431E, 2002; Rowe et al., 2002; Robert and Christian, 2003; Warith et al, 2002). Furthermore, disposing of scrap tires in landfills takes much more space due to their uneven settlement and tendency to rise to the surface that will damage landfill covers. The toxic substances liberated from the predisposed tire materials can also cause serious environmental impacts (Rowe et al., 2005). The extended producer responsibility policy for tire stewardship program in Ontario supports the goa approach philosophy through 3Rs-reduce, reuse and recycling programs (EPR, 2008). -approach desperately advocates the reuse of discarded tires. As a result, finding more options than available for scrap tire reuse is more important than disposing these tires to landfills and incinerating them. An alternative use of scrap tires, Mondal and Warith (2008) and Rowe et al. (2005) tried to use the mixed tire chips of size 10-100 mm for landfill leachate treatment but the performance of mixed tire chips was not conducive to the landfill leachate treatment compared to crushed stones and sands. However, on the basis of their investigations, it may be concluded that relatively more homogeneous tire chips than existing tire chips may provide a better performance in the field. In addition to the problems of using scrap tires, landfill leachate treatment becomes another challenging issue embedded with high cost technology and water pollution through leaching. To protect the groundwater environment from contamination, there is an urgent need for treating landfill leachate before final discharge to lagoon or wastewater treatment plants to reduce the cost burden. Recent studies have suggested that aerobic bio-filtration can be a proven low-cost technology for landfill leachate treatment through the use of suitable size of tire chips (Mondal and Warith, 2008). However, rapid clogging in the existing leachate treatment system is a major issue considering particularly its cost to be addressed to resolve in an economical way. Hence, the removal rate of contaminants and study of hydraulic conductivity of the tire chips pertaining to the pore-size distribution could provide the information for optimal sizes of tire chips. Keeping the above views in mind, the purpose of this study is to design a cost effective bio-filter for secondary treatment of landfill leachate through the trials of different sizes of tire chips within acceptable remediation limits. The specific objectives of this research work are to (1) find out the suitable size of tire chips for effective filtration bed of a secondary bio-filter, and (2) assess the clogging effect of tire chips through measuring the reduction of hydraulic conductivity.

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