Evaluation of coagulation-flocculation process as pretreatment option for landfill leachate using alum, ferric chloride and polyacrylamide grafted gum ghatti
Mohini Verma Department of Civil and Environmental Engineering Birla Institute of Technology, Mesra Department of Civil and Environmental Engineering, BIT Mesra Ranchi, Jharkhand, India
[email protected]
Shubhrasekhar Chakraborty Department of Civil and Environmental Engineering Birla Institute of Technology, Mesra Department of Civil and Environmental Engineering, BIT Mesra Ranchi, Jharkhand, India
[email protected]
R. Naresh Kumar a,b, Ph.D. a Department of Civil and Environmental Engineering, Birla Institute of Technology, Mesra b Adjunct Lecturer, School of Natural Sciences, Edith Cowan University, Western Australia, Australia Department of Civil and Environmental Engineering, BIT Mesra Ranchi, Jharkhand, India
[email protected]
Abstract Coagulation-flocculation was studied as pretreatment option for stabilized landfill leachate from a dumpsite in Ranchi, India. Alum, ferric chloride and a novel Polyacrylamide grafted Gum Ghatti (GGI-g-PAM) were used for coagulation-flocculation. Experiments at different coagulant doses and pH were conducted in Jar test apparatus, process evaluation was based on removal of chemical oxygen demand (COD), total suspended solids (TSS), turbidity, ammonia and color. Alum at 9500 mg/L and at pH 6 led to 63% COD removal, 71% TSS removal and 59% turbidity removal. Ferric chloride at 2500 mg/L and at pH 4 led to 80% COD removal, 53% TSS removal and 65% turbidity removal. GGI-g-PAM at 100 mg/L and at pH 7 led to 38% COD removal, 90% TSS removal and 22% turbidity removal. Ferric chloride at 2000 mg/L dose and at pH 4 led to 54% ammonia removal but color removal was insignificant. Alum at 9500 mg/L and at pH 6 removed 79% color but ammonia removal was insignificant. GGI-g-PAM was ineffective for ammonia and color removal. Further studies are needed to test GGI-g-PAM as post-treatment option since as pretreatment option it produced lower removal efficiency for all the parameters evaluated.
1016
Keywords: Landfill leachate, coagulation-flocculation, alum, ferric chloride, Gum Ghatti Introduction Unscientific open dumping of municipal solid wastes (MSW) leads to the generation of landfill leachate (Sharholy et al., 2008). Landfill leachate is generated when precipitation and moisture content of the disposed wastes percolates through the waste layers in open dumps (Ogundiran and Afolabi, 2008). Combination of physical, chemical and biological processes in the waste dump leads to the transformation of pollutants from the wastes into leached water. Leachate is characterized by presence of various organic and inorganic substances (Kjeldsen et al., 2002). There are many factors which influences leachate composition in landfills such as refuse composition, moisture content, biodegradation rate, climatic conditions, hydrogeology and landfill age (El-Fadel et al., 2002). According to the landfill age, leachate can be classified into three categories i.e., young, medium and stabilized. Leachate from a landfill less than five years is termed as young leachate which typically has high BOD:COD ratio with acidic pH. Landfill between five to ten years are often known to produce medium age leachate with BOD:COD ratio in the range of 0.5 to 0.1 and slightly basic pH. Landfill more than ten years old are known to produce stabilized leachate. Stabilized leachate with BOD:COD ratio of
