Insight on pollution and energy recovery potential of leachate from landfill sites of Northern India

Abstract

Abstract Leachate is a highly digested by-product of waste degradation originating from municipal landfills. It has high pollution potential and needs to be treated before disposal. Environmentally sustainable technology like microbial fuel cells (MFCs) is becoming a novel choice as it treats and also produces energy from leachate. Nevertheless, the suitability of energy (biogas) recovery depends upon the leachate characteristics. The leachate from three landfill sites of Ghazipur, Okhla and Bhalswa in Delhi was characterized. The findings revealed that the organic strength of leachate in terms of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) do not support biogas production. Further, high concentrations of NH3-N and chloride may exert inhibitory effects on biomethanation. Heavy metals such as Fe, Cr and Ni show a positive effect, whereas Zn and Cu inhibit the leachate to biogas conversion. Leachate Pollution Index (LPI) values for Ghazipur, Okhla and Bhalswa were 24.77, 26.28 and 24.64, respectively. Since the LPI is greater than 15, leachates need to be treated. When pollution potential was assessed using sub-indices, the comparative leachate pollution for organics is Okhla > Bhalsawa > Ghazipur, for inorganic pollutants Ghazipur > Okhla > Bhalwsa, and for heavy metals, the order follows Okhla > Bhalswa > Ghazipur. Further, PCA analysis of the three landfills shows that the leachate from Ghazipur and Bhalswa are organics rich. For Okhla, the leachate characteristics are mostly determined by inert waste contributed largely by construction and demolition (C and D) waste. Thus, Gahzipur and Bhalswa landfills may better support leachate-gas production over the Okhla landfill.