Utilization of agrowaste for arsenic biosorption: enhancing efficacy and assessing the suitability of plant and animal growth in post-adsorbed solution.

Abstract

Arsenic is known to have detrimental effects on living bodies when exposed to contaminated groundwater. Therefore, a cost-effective way to eliminate arsenic from aquatic sources is essential. Our study evaluated the efficacy of eight different types of easily accessible agricultural wastes for arsenic removal. The safety assessment of the post-adsorbed solution in plant and animal test models such as Allium cepa and Daphnia magna was also evaluated. The results showed that the efficiency of the adsorbents depends on the type of agricultural waste utilized. In the case of citrus agrowastes, maximum biosorption (94-95%) was attained at the lowest 15min contact time, indicating very rapid saturation of adsorption sites for other adsorbents; with an increase of contact time, there was a gradual increase in biosorption of arsenic. Allium cepa toxicity test showed that arsenic exposure caused a significant decrease in root length (2.80 ± 0.89cm) and a reduction in mitotic index (6.31 ± 1.79%) that can be reverted to normal after the roots were grown in a post-adsorbed medium. Similarly, solutions treated with different agricultural wastes except citrus biosorbents showed significantly higher survival rates and litter sizes of Daphnia magna post biosorption. Agricultural waste with citric characteristics removed arsenic more effectively than other chosen agricultural wastes, but the solution generated by biosorption with citric agrowaste does not support plant and animal growth. Among the other chosen adsorbents, rice husk has been found to be highly suitable for plant and animal growth by reducing the toxic effects of arsenic.