Leah Suchet1 and Robert W. M. Pott1,
1Department of Process Engineering, Stellenbosch University, South Africa
South Africa’s bourgeoning seaweed concentrate industry derives an agricultural stimulant from Ecklonia maxima through an extraction process that produces a significant amount of waste biomass (mostly comprised of the solid cell components), a stream rich in structural biomaterials such as cellulose, fucoidans and alginate. Currently, this waste is discarded into the municipal waste system, costing the company money as well as losing a significant quantity of valuable materials. Hydrolysis of structural carbohydrates within the waste would serve to solubilise the solid into a liquid which might be applied in agriculture, while yielding valuable bioactive oligosaccharide products. The current state of the art has demonstrated alginate hydrolysis typically using aggressive acid treatments at high temperatures, or using expensive (and limited availability) alginate lyase enzymes. These conditions are not often feasible in post-hoc industrial processing – where companies are loath to invest in high-temperature or high-pressure reaction vessels, or expensive reagents. Within the limitations of industrial scale waste valorisation, the current study investigated ambient temperature chemical hydrolysis of both pure alginate and waste biomass. Sulphuric, formic, and acetic acids at various concentrations either alone or in combination with hydrogen peroxide were tested as digesting agents on both pure alginic acid and industrial waste, at ambient temperature. Degradation was quantified using a total solubilised carbohydrate methodology. Results surprisingly indicated improved degradation using organic acids over mineral acids, while the inclusion of hydrogen peroxide significantly improved solubilisation. Future work will focus on identifying and quantifying the oligomers produced as a function of reaction time.