USE OF PLANTAIN (Musa paradisiaca) WASTES FOR THE REMOVAL OF LEAD AND CHROMIUM IN EFFLUENT FROM BATTERY RECYCLING PLANT

Abstract

Industrial effluent often contains heavy metals which bio-accumulate and persist in the environment, thereby constituting health problems. Plantain (Musa paradisiaca) waste, which are easily available, could be used to produce resource materials such as activated carbon that are of public health importance. However, there is a dearth of information on the use of activated carbon from plantain in Nigeria. Therefore, this study assessed the use of plantain wastes for the removal of lead and chromium in effluent from battery recycling plant. Plantain wastes were collected from a plantation, sun-dried and ground. These were then carbonized and activated using industrial oven at 400°C. An Acid-Lead battery recycling plant in Ogunpa, Ibadan North- West local government area was purposively selected. Samples of effluent from the point of discharge into Ogunpa river (100m from the residential area) were subjected to physico-chemical (pH, conductivity, Total Suspended Solid (TSS); (Lead (Pb), and Chromium (Cr)) analyses, using American Public Health Association methods. Adsorption capacity was studied; using Association of Official Analytical Chemist method at varied effects of pH (2 to 12) and adsorbent doses (0.1 to 2.0g) with treatments by activated carbon from plantain peel (A), plantain stalk (B), while commercial activated carbon (C) served as control. Batch experiment was adopted in determining the adsorption isotherms of the adsorbents. Initial and final concentrations of Pb and Cr were determined by Atomic Absorption Spectroscopy. Results were compared with National Environmental Standards and Regulations Enforcement Agency (NESREA) for industrial effluent. Data were analysed using descriptive statistics, paired t-test, Langmuir and Freundlich Models, and ANOVA at 5% level of significance. Means of pH, conductivity, TSS, Ph and Cr of the effluent sample were: 2.0±0.2, 2164.7±0.6µs/cm, 2001.7±25.2mg/I, 31.3±0.0mg/I and 13.5±0.0mg/I respectively. These were above the safe limits of conductivity (1000µs/cm), TSS (28mg/I), Pb (0.05mg/I), Cr (0.05mg/I) and more acidic than pH 6-9 of NESREA, which is toxic to human. The adsorption capacity by A, B, and C increased correspondingly with pH for Pb (1.37 to 1.93): (1.24 to 1.81); (1.22 to 1.82) and Cr (0.22 to 0.64); (0.23 to 0.53); (0.36 to 0.71) respectively. Adsorbent dose decreased for Pb (12.73 to 0.69); (13.5 to 0.73); (9.10 to 0.60) and Cr (1.71 to 0.17); (1.95 to 0.19); (0.97 to 0.18) respectively. The highest quantities of Pb and Cr were removed at pH for Pb (94.97% and 68.02%). However, optimum dosage occurred at 1.5g for Pb (96.61%) and 2.0g for Cr (58.91%). There was significant difference between Pb and Cr removed by A and B compared with C. The level of Pb and Cr post-treatment was below the NESREA's. The adsorbents showed satisfactory fits to Langmuir and Freundlich models. Adsorbents had potentials for removing lead and chromium from effluent generated from battery recycling plant with plantain peel activated carbon having the highest adsorption capacity. Treatment of effluent with plantain wastes should be encouraged in battery recycling plant, to promote public health safety and enhance effective waste management.