Scientists have found a way to remove cyanide in cassava mill effluents (CMEs) that contaminate the soil. The study, published in the American Journal of Environmental Sciences, indicated that using organic wastes from certain fruits can also improve soil enzymes and enhance soil nutrients while eliminating cyanide in contaminated soil samples.

• The scope of the study included the bio-stimulation of organic wastes using microorganisms found in food waste to degrade cyanide. In particular, the design of the study called for applying the wastes as a substrate to identify the process behind the removal of cyanide.
• To test their theories, the team selected banana, pineapple, and watermelon wastes. These were then bio-stimulated in cyanide-contaminated soil.
• Each sample contained 100 g of CME, and differing amounts of organic food wastes were added to it. By percentage, soil samples were amended with either one, five, and 10 percent of banana, pineapple, and watermelon waste, and set-ups were monitored for cyanide reduction for 28 days. During this time, samples were collected every four days to test for total cyanide concentration, total heterotrophic bacteria, and enzyme activity.
• After the trials, researchers discovered that food waste with 10 percent watermelon provided better cyanide reduction over other types of food waste. In addition, the shortest disintegration rate was noted in the one phase-decay equation of one percent banana, five percent pineapple, and 10 percent watermelon waste treatment.
• Other physicochemical properties of the soil were also identified. This revealed a positive correlation between soil organic carbon content and microbial biomass and its population.

Based on their findings, researchers concluded that organic food waste from banana, pineapple, and watermelon is effective in improving soil nutrients and degrading cyanide from CME-contaminated soil.