Abstract
Sanitary landfill leachate (LL) composition varies according to climate variables variation, solid waste characteristics and composition, and landfill age. Leachate treatment is essentially carried out trough biological and physicochemical processes, which have showed variability in efficiency and appear a costly solution for the management authorities. Electrocoagulation (EC) seems a suitable solution for leachate treatment taking into account the characteristics of the liquor. One of the problems of EC is the electrode passivation, which affects the longevity of the process. One solution to this problem could be the replacement of the electrode by one made of recyclable material, which would make it possible to change it frequently and at a lower cost. The objective of the present work was to evaluate the removal of heavy metals (As, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Se and Zn) and coliforms from a LL by EC using electrodes made from steel swarf (SfE) up to 8 h. Removal efficiencies of detected heavy metals were 51%(Cr), 59%(As), 71%(Cd), 72%(Zn), 92%(Ba), 95%(Ni) and >99%(Pb). The microbial load of coliforms in leachate was reduced from 10.76 × 104 CFU/mL (raw leachate) to less than 1 CFU/mL (after treatment with SfE) (i.e., approximately 100% reduction). The use of SfE in EC of LL is very effective in removing heavy metals and coliforms and can be used as alternative treatment solution for such effluents.
Highlights
Sanitary landfill leachate (LL) is a type of wastewater with high loads of organic and inorganic compounds, namely natural and synthetic organics, xenobiotics, ammonia, nitrate, pathogenic microorganisms, and heavy metals
The LL is composed of four different fractions: the natural humidity of the garbage, which increases in the rainy events; the aqueous constitution of organic matter, which is released during the decomposition processes; the bacteria in the trash, which secrete enzymes that dissolve organic matter with liquid formation; and from existing water sources in the area [1]
The most used biological and physicochemical processes have showed variation in efficiency and high operation costs due to the use of UF and RO, and, the filtered material is returned to the landfill which will become a problem in the future [1,9]
Summary
Sanitary landfill leachate (LL) is a type of wastewater with high loads of organic and inorganic compounds, namely natural and synthetic organics, xenobiotics, ammonia, nitrate, pathogenic microorganisms, and heavy metals. The leachate composition is very varied and heterogeneous, but generally contains [1,2,3]: High concentration of dissolved organic matter (as chemical oxygen demand (COD)), ammoniacal nitrogen (N-NH4+ ), nitrate nitrogen (N-N03− ), chloride (Cl− ), potassium (K+ ), sodium (Na+ ), calcium (Ca2+ ), iron (Fe2+ ), magnesium (Mg2+ ), manganese (Mn2+ ), sulfate (SO4 2− ), hydrogen carbonate (HCO3 − ), heavy metals (lead (Pb2+ ), chromium (Cr3+ ). The most used biological and physicochemical processes have showed variation in efficiency and high operation costs due to the use of UF and RO, and, the filtered material is returned to the landfill which will become a problem in the future [1,9] The treatment of LL involves the use of biological processes (e.g., activated sludge, stabilization ponds and constructed wetlands) and physicochemical processes (e.g., coagulation, AOPs, ultrafiltration (UF) and reverse osmosis (RO)) [1,2,3,5,7].
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