Treatment of Waste Water for Irrigation Using Activated Carbon and Biochar from Crop Residue
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Date
2017-07
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University of Ghana
Abstract
Sustainability of urban vegetable farming has engaged many people for its economic benefits. The challenge to improving vegetable yield is water scarcity during dry season. Many farmers have therefore resorted to using waste water for irrigation, with the potential of contaminating crops. Contaminants in waste water are of biologically and physicochemically origin. This research aimed at treating waste water contaminated with heavy metals using activated carbon and biochar.
Cost effective technology was applied to produce biochar and activated carbon from crop residue. Six heavy metals were initially tested in the waste water and the adsorbents. Three of the heavy metals, i.e. Zn, Mn, and Cr were detected in the adsorbents only while the other three, namely Iron Fe, Ni and Pb were detected only in the waste water. Biochar and activated carbon therefore served as adsorbents and was used to decontaminate the Fe, Ni and Pb contained in the waste water. Waste water for vegetable irrigation was sampled from Korle-Bu backyard gardens. Treatments used were 100 g and 200 g each of biochar and activated carbon. One litre of sampled waste water was filtered through each amount of the adsorbents in a Randomized Complete Design. There was significant difference in Fe decontamination between the Control (untreated waste water) and Treated Waste water at P ≤ 0.05 using LSD test but between the different adsorbents, there were no significant differences in Fe decontamination. There was significant difference in Ni decontamination between the control and 100 gram activated carbon. Ni was completely decontaminated by the 100 grams activated carbon. Finally, there was no significant difference in Pb decontamination between the control and all adsorbent treatments. In general, all adsorbents contributed to heavy metal decontamination in the waste water although insignificant in some cases. It was therefore concluded that activated carbon and biochar can be used for heavy metals decontamination in waste water hence recommended for treatment of waste water for irrigation.
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Keywords
metal decontamination, Fe decontamination, treating waste water contaminated, urban vegetable farming, Sustainability, improving vegetable yield, contaminating crops, produce biochar, activated carbon