Material Flow Analysis and Resource Recovery Potential Analysis of Selected Fruit, Vegetable and Nut Waste in Kenya

Abstract

In Kenya, agriculture is an important economic activity, which implies that a significant amount of bio-waste is generated. This is on one hand a waste management problem, but on the other hand, it is an opportunity for creating a sustainable bioeconomy. Therefore, this study investigates the potential recovery of bioresources from Kenyan bio-waste. The study first quantifies occurrence, current usage and disposal of three selected biomass types, being banana, Irish potato and coconut waste. Next, material flow analysis is used to systematically track the mass flow of these wastes. Finally, the potential of biomolecules, biomaterials and bioenergy from the waste streams is evaluated. The study revealed that about 6007, 426 and 50 kt of banana, Irish potato and coconut biomass is wasted. All these wastes can be biorefined, offering potential towards recovery of; flavonoids (74 kt), starch (377 kt), cellulose (2001 kt) and biogas (1757 GWh), being the total potential of the main bioresources from the three waste streams. The study therefore, concluded that, with proper waste collection, sorting and valorisation, there is a huge potential for bioeconomy in Kenya, at the same time reducing waste management problems. Graphical Abstract

Kinetic modeling of phenolic compounds extraction from nutshells: influence of particle size, temperature and solvent ratio

“…To this end, phenolic compounds have been obtained from agricultural residues and by-products such as peels [6], leaves [7], seeds [8], pomace [9], woody bark [10], nutshells [11], among others. The extraction of phenolic compounds from nutshells is particularly noteworthy due to their abundance and ease of handling due to the lower moisture content of this type of biomass [12], as residual biomasses with high moisture content might be prone to fast degradation of the bioactive molecules. Furthermore, nutshells have the potential to have a high phenolic content [11,12].…”

“…The extraction of phenolic compounds from nutshells is particularly noteworthy due to their abundance and ease of handling due to the lower moisture content of this type of biomass [12], as residual biomasses with high moisture content might be prone to fast degradation of the bioactive molecules. Furthermore, nutshells have the potential to have a high phenolic content [11,12].…”

“…Thus, the nut value chains in Kenya can produce potential bio-waste quantities of about 52 kt from coconut (at 47% waste [16]), 4 kt from groundnut (at 25% waste [18]), 8 kt from cashew nut (at 60% waste [16]), and 8 kt from macadamia (at 47% waste [19]). Despite the fact that these nutshells are abundant and stable, approximately 95% of this waste is disposed of in open landfills and 4% is burned to generate energy [12]. Yet, the shells contain potentially high quantities of phenolic compounds, up to 4046 mg GAE/100 g dw [20] measured by the total phenolic content (TPC) approach.…”

“…This study, therefore, aims to understand and optimize the process parameters of TPC extraction from the shells of peanuts, coconuts and macadamia nuts by conventional solid-liquid extraction and to determine the kinetic model that can best describe the process. The nutshells studied were chosen due to their abundance and lower moisture content [12]. For the optimization, the optimal particle size, temperature, and ethanol-water solvent ratio were examined based on an I-optimal design, in combination with response surface methodology (RSM) modeling.…”