Waste Water Treatment for Irrigation using Charred Biomass Residue

Abstract

Urban vegetable production in Ghana has engaged the exuberant youth in agriculture for its economic benefits. The impact of climate change coupled with erratic seasonal rainfalls has exacerbated crop failure due to water scarcity. Consequently, most urban farmers have resorted to the use of untreated wastewater for irrigation, especially in the dry season. Our study therefore aimed at treating municipal wastewater contaminated with heavy metals for vegetable irrigation. Two different charred biomass residues, biochar (BC) and activated carbon (AC), were used as adsorbents to remove heavy metals from wastewater. The two treatments consisted of 100 and 200 g of BC, and 100 and 200 g of AC, with one liter of untreated wastewater (WW) serving as the control. Heavy metals removed from the wastewater were Iron (Fe), Nickel (Ni), and Lead (Pb). Compared to the control, there were significant differences (p ≤ 0.05) in Fe decontamination by the biochar and activated carbon in their respective rates, but comparing AC treatments to that of BC, there was no significant reduction of Fe concentrations after wastewater treatment. The adsorbents had no significant impact in reducing Ni in WW except for the 100 g AC that completely decontaminated Ni. Both BC and the AC had no impact on Pb decontamination from the wastewater. In general, activated carbon was desirable in decontaminating heavy metals from wastewater. However, the suitability of an adsorbent in decontaminating a given heavy metal from wastewater depends on the kind of heavy metal and the characteristic of the adsorbent used.