| dc.description.abstract | The capacity of Black soldier fly (BSF) larvae to feed on organic matter and yield a protein rich biomass which can naturally be consumed by animals, offers an innovative opportunity of using waste rapidly generated in cities to produce tons of BSF for livestock feed. Efforts to recycle such waste using this insect has gained popularity but there is a public health concerns on the quality of larvae raised from such substrate to be used in the food system as feed ingredients. Contrary to microbial contaminants which are inactivated by BSF larvae, chemical contaminants like heavy metals are a threat to this industry as they are reported to accumulate in the BSFL posing a threat to consumers along the food chain. Heavy metals naturally occur in the earth crust and are released via natural disasters but a greater percentage of their release to the environment is largely attributed to anthropogenic factors. A study was conducted to investigate the effect of biochar introduction to BSF feed as a feed additive on heavy metal accumulation in BSF larvae. Biochar is a carbonaceous
product of pyrolysis which is nontoxic and previous studies have reported its efficiency in binding toxins and general animal health when ingested as supplements. The objective of this study was to establish the adsorptive capacity of locally produced biochar in managing heavy metal accumulation associated with BSF reared on contaminated municipal organic wastes. This being so, optimization
studies on rice husks biochar (RHB) and coconut shells biochar (CSB) capacity to adsorbed Cadmium metal were conducted. Adsorption behavior of Cadmium (Cd) onto the RHB and CSB with respect to the various parameters of influence was studied. The equilibrium data from the batch adsorption experiments was used to design kinetic and isotherms models. The isotherms showed a best fit of Freundlich model for RHB and CSB which informs heterogeneity kind of adsorption and exponential distribution of adsorption sites and their energies. Kinetic data indicated a chemisorption process of adsorption for both biochar types and this was best described by the PSO model. Furthermore, the remediation studies for Cd accumulation in BSFL using biochar feed additive was done in a CRD experiment. BSF larvae were fed on Irish potato peels spiked at varied Cd concentration levels and an equal amount of biochar with respect to type was mixed to the feed as treatment. Thereafter, the harvested BSF larvae were acid digested and analyzed for Cd using an
AAS which detected only a small fraction of Cd2+ in the BSF larvae as well as in the food remains. This showed that the substantial amount of Cd2+ which was unaccounted for were retained in the biochar. These results indicate that RHB and CSB are suitable adsorbent which can effectively manage heavy metals. Findings from this study can therefore provide a basis for using biochar as a low-cost adsorbent to effectively remediate the heavy metal accumulation threat in BSF reared on contaminated organic waste. | en_US |
