Biogas Production from Ecklonia Maxima using an Anaerobic Digestion Process: Investigation, Analysis and Optimisation

The research presented investigates the use of brown macroalgae, Ecklonia Maxima, which is widely available in South Africa, as a potential feedstock for biogas production. The process utilised is anaerobic digestion (AD), which is able to utilise a wet feedstock, therefore removing the additional drying costs required from other processes. Four inocula were investigated at both mesophilic (C) and thermophilic (C) temperatures. These included two synthetic inocula as well as an organic inoculum and a starter fluid from the wastewater treatment plant.The BioGanic/Ecklonia Maxima system was subjected to a series of pre-treatment processes to investigate if the biomethane yield could be improved upon. Mechanical, chemical and microwave pre-treatment was applied at both mesophilic and thermophilic temperatures.Kinetic modelling indicated that the first order modified Gompertz equation was a good fit for the raw seaweed and pre-treated seaweed data, which allowed for the determination of the maximum methane yield for the batch system. It also allows for the prediction of the performance of the seaweed in biomethane production.A techno-economic study with two case studies proved that seaweed biomaterial could produce biomethane, which could then be converted to electricity using a CHP unit.