Global Journal of Human-Social Science, B: Geography, Environmental Science and Disaster Management, Volume 22 Issue 3

Abatement of Polluting Effects of Waste Dump Leachates using Different Coagulants Oso, S. α , Taiwo, A.M. σ , Bamgbose, O. ρ , Olayinka, O. Ѡ , Terebo, O. ¥ , & Soyingbe, A.A. § Abstract- This study assessed the effectiveness of different coagulants for treating leachates before their release into the environment. Three inorganic coagulants (ferric chloride, ferrous sulphate and alum) and one organic coagulant [ Moringer Oleifera seed (MOS)] were used in a jar test to determine the optimum pH and dosage for the coagulants. Raw and treated leachates were analysed for physiochemical parameters such as pH, chemical oxygen demand, Total solids, Pb and Cr. The optimum pH for ferric chloride, ferrous sulphate, alum and MOS was 7, 7,6 and 10 respectively. While the optimum dosage for each coagulant was 3g/L, 3g/L, 5g/L and 5g/L respectively. The analysis of the raw leachate sample showed that it was highly polluted (Dry season: COD – 3000mg/L, TSS – 2369mg/L, Cr – 0.075mg/L, Pb – 0.25mg/L and Mn – 0.29mg/L; Wet season: COD – 3000mg/L, TSS – 2369mg/L, Cr – 0.075mg/L, Pb – 0.25mg/L and Mn – 0.29mg/L).Coagulants removal efficiency (RE) for COD ranges from 12% to 41% with ferric chloride having the highest removal efficiency. All the coagulants were efficient in reducing the level of heavy metals in the sample leachate. The RE ranges from 55% to 95.6% with MOS having the highest RE of 95.6% for lead. The coagulants showed significant difference (at P < 0.05) in their RE for some of the parameters treated. The inorganic coagulants (ferric chloride, ferrous sulphate and alum) showed no significant difference (P > 0.05) in the removal of COD, while the organic coagulant (MOS) was significantly different at P < 0.05 from the inorganic coagulants. Over all, Alum showed to be a better coagulant than other coagulants in reducing the physiochemical parameters of leachates while MOS is a suitable substitute for alum. It was also observed that there was no significance (P > 0.05) in the removal efficiency of the coagulants in both dry and wet seasons. Seasonality has no effect on the effectiveness of the coagulants. Keywords: leachates, coagulants, jar test, removal efficiency, seasonality. I. I ntroduction he continuous growth in population and industrialization globally has led to increases in solid waste generation and the problem of its management. Solid waste collection and disposal are among the most serious threats to waste management in most cities in developing countries (Donevska et.al ., 2006). Solid waste is any material, which is not in liquid form, and has no value to the person who is responsible for it (Zurbrugg, 2003). Babatola (2008) described waste as any material lacking direct value to the user and so must be disposed of. The poor management of solid wastes constitutes a disaster for human health and leads to environmental degradation (Achankeng, 2003). One of the most important issues of concern in open dump or landfill waste disposal method is the issue of leachate generation and its potential for downgrading water resources systems (Sartaj et.al ., 2010). Leachates are defined as the aqueous effluent generated as a consequence of rainwater percolation through wastes, biochemical processes in waste’s cells and the inherent water content of wastes themselves (Lee et.al. , 2012). The generated leachate can cause significant environmental damage, becoming a major pollution hazard when it comes into contact with the surrounding soil, ground or surface waters. This leachate often contains a high concentration of organic matter and inorganic ions, including ammoniacal nitrogen and heavy metals; posing great treat to human (Zouboulis et al., 2008). The quality of leachate is affected by factors such as dumpsite age, precipitation, seasonal weather variation, waste type and composition. Treatment methods are highly dependent on leachate characteristics and tolerance of the method against changes in leachate quality such a variable nature along with other factors. The leachate treatments success depends also on the characteristics of the leachate and age of the landfill. Therefore, in order to avoid environmental damage, landfill leachate must be collected and appropriately treated before being discharged into any water body (Oh et.al ., 2007). Coagulation is widely used for wastewater treatment. This treatment is efficient to operate and the operating cost is low (Wang et.al ., 2008). It has many factors that can influence the efficiency, such as the type and dosage of coagulant, pH, mixing speed and time and retention time.The optimization of these factors may influence the efficiency (Wangand Bank, 2007). Coagulation destabilizes the colloidal suspension of the particles with coagulants and then causing the particles to agglomerate with flocculants. After that,it will accelerate separation and thereby makes the effluents clearer (Gnandi et.al ., 2005). T © 2022 Global Journals Volume XXII Issue III Version I 55 ( ) Global Journal of Human Social Science - Year 2022 B Correspondence Author α : Department of Environmental Management and Toxicology, Federal University of Agriculture, Abeokuta. e-mail: kaybam2002@gmail.com Author σ ρ Ѡ : Department of Environmental Management and Toxicology, Federal University of Agriculture, Abeokuta. Author ¥ : Department of Environmental Health, College of Health Technology, Akure, Nigeria. Author § : Department of Environmental Health Sciences, Ogun state College of Health Technology, Ilese.