Removal of Lead (Pb) from Mining Wastewater by Fabricated Filter from Coconut (Cocos nucifera) Husk and Banana (Musa sp.cv.Cardava) Lignocellulosic Materials

Abstract

INTRODUCTION

Caraga has been a home to a number of mining companies, which produce wastewater. Heavy metal-rich mining effluent pollutes water resources if discharged without treatment. Exposure to heavy metals such as Pb is proven to cause adverse effects on human health. It is therefore imperative to treat wastewater before discharging them back to the environment. However, standard treatment facilities are only affordable to well-off mining firms; small-scale miners usually resort to indiscriminate wastewater discharge. This encouraged the researcher to create inexpensive and sustainable wastewater filter from common agricultural-wastes---coconut husks and banana pseudostem.

METHODS

Forty-five cm2 long, 1.27 cm thick mat-like filters with 0.5 mm pore size were fabricated out of weaved coconut husks and banana pseudostem. Wastewater collected from a Gold-ore Processing Plant in Tambis, Barobo, Surigao del Sur were filtered through---banana filter-single sheet (treatment 1), banana filter-double sheet (treatment 2), coconut filter-single sheet (treatment 3), coconut filter-double sheet (treatment 4), and unfiltered water (control). Water samples were tested for Pb content using Microwave Plasma-Atomic Emission Spectrometer at the Department of Agriculture's Integrated Laboratories in Butuan City.

RESULTS

The results showed that unfiltered mining wastewater contained 12.33 ppm Pb. After filtration, that number decreased to 8 ppm for banana filter-single sheet (35.12% reduction) and 7 ppm (43.23% reduction) for double sheet. For coconut filter, the water filtered through single sheet was found to have 8.33 ppm Pb (32.44% reduction), and 8 ppm Pb (35.12% reduction) for double sheet. Analysis of variance revealed that there is a significant difference in the Pb concentration of water before and after filtration.

DISCUSSIONS

The results demonstrate that the amount of Pb in unfiltered mining wastewater is 62 times higher than DENR's effluent standard for Pb (0.2 ppm). The coconut husk and banana lignocellulose filters have significantly reduced the Pb concentration. The significant reduction of Pb after filtration could be attributed to the lignin-bonded cellulose in the filters. Studies showed that lignocelluloses have high adsorption capacity to metal ions (Ge, Li, Kong, Song, and Wang, 2014; Nair, Panigrahy, and Vinu, 2014). If mass-produced, the filters could not only minimize Pb pollution, it could also provide livelihood to locals.