ABATEMENT OF POLLUTING EFFECTS OF WASTE DUMP LEACHATE USING ORGANIC AND INORGANIC COAGULANTS

Abstract

Pollution is one of the major challenges associated with the release of leachates from a landfill either naturally or through designated wells. Effectiveness of some organic substances that can act as coagulants (powder prepared from mature dried Moringa oleifera seeds (MOS) and maize cobs (MC)] and an inorganic coagulant (Alum) were investigated for the abatement of pollution in the leachate collected from Igbatoro dumpsite, Akure, Ondo State during wet and dry seasons of 2018. The leachates were analyzed for different physico-chemical parameters such as pH, Alkalinity, Chemical oxygen (COD), Hardness, electrical conductivity (EC), total dissolve solid(TDS), total suspended solid (TSS), Chloride, Nitrate, Phosphate, and Sulphate by standard methods. Heavy metals (Cr, Pb, Mn) concentration in the leachates was determined by Atomic Absorption Spectrophotometer (AAS). Leachate samples had pH, alkalinity, TDS, and Sulphate within permissible levels of Federal ministry of environmental guidelines for both dry and wet seasons (7.8±0.2, 65.2±3.2 mg/L, 127±11 mg/L, 210±11 mg/L and 8.1±0.1, 69±1mg/L, 110±13 mg/L, 180±16 mg/L) respectively, while values of COD (3120±102 mg/L for dry season and 3150±78 mg/L for wet season were higher than FMENV limit. The mean values of Hardness, EC, TSS, chloride, nitrate, phosphate observed for dry season were 1214±112 mg/L, 5650±110 mg/L 522±15 mg/L, 910±55 mg/L, 123±13 mg/L, 210±11 mg/L, respectively while for wet season, the respective values were 1265±72 mg/L 7430±124 mg/L, 610±13 mg/L, 970±32 mg/L, 87±10 mg/L, and 301±25 mg/L. The results of the coagulation experiments showed that organic and inorganic coagulants were most efficient under alkaline and neutral media. The optimum pH and coagulant dosages were as follows; for MOS (pH 10, 5 g/L), MC (pH 7, 3 g/L) and Alum (pH 8, 5 g/L). The results obtained after the treatment of the leachates showed that alum had better reduction levels for pH, alkalinity, COD, TSS, Nitrate, and phosphate for dry season with mean values of 5.43±0.1, 7.18±0.88 mg/L, 2162.78±109 mg/L, 160.5±6.2 mg/L, 6.76±0.74 mg/L, 10.91±0.85 mg/L respectively, while maize cob (MC) reduced EC, TDS and Chloride with better abatement (4972 ± 301 mg/L,110.49±6.81 mg/L, 565.11±32.12 mg/L and MOS showed high reduction for Acidity, hardness and sulphate with mean values of 1.81±0.35mg/L, 513.88±22mg/L, and 92.40±12.5mg/L. Alum had better removal percentages for heavy metals in comparison to other coagulants. There were seasonal variations with significant difference among the three (3) coagulants used for treatment. Treatments with the coagulants have showed higher removal efficiency for heavy metal concentration and some physico- chemical parameters except for chloride, EC, and sulphate for both seasons. Conclusively, experimental data showed that Moringa oleifera and maize cobs demonstrated coagulation potentials that compared alum in the favourably with abatement of pollution parameters of leachates. Keywords – Waste dumpsite, organic and inorganic coagulants, coagulation.