Browsing by Author "Wan Nur Asiah Wan Mohd Shukri"

Microbial fuel cell (MFC) suffers from low energy gain yield (output/cost) and is unsuitable for most practical implementations. Microbial zinc/air cell employing freely suspended white rot fungal Phanerochaete chrysosporium fed with empty fruit bunch (EFB) has demonstrated promising prospects as a sustainable MFC. This work aimed to increase the energy gain yield of the system by minimizing external control features, implementing low-cost design, and increasing the energy output. To fulfil the power output for most low-power applications, multiple MFCs need to be connected in a stacking configuration. However, the variation in individual MFC’s electromotive force (e.m.f) due to living microbes activities induces parasitic currents in parallel configuration. This work introduced a novel open-parallel unit-cell configuration for MFC stacking. All unit cells were connected in parallel configuration but hydrodynamically connected i.e. they shared a common electrolyte. Using this configuration, the discharge capacity of the MFC stack was extended 3.4 times, the total power output was increased by 2.6 times compared to the common parallel configuration, and the parasitic current was effectively eliminated. The microbial zinc/air cell is an air-cathode MFC. The air cathode is the most expensive component in an air-cathode MFC and, in most cases, requires an air aeration system. Therefore, this work designed and fabricated a low-cost and easy-to-fabricate air cathode. It is low cost because it is non-catalytic and the fabrication did not require special processes, only mere mechanical press of the cell holders. Further, the air cathode components of carbon felt, carbon fibre sheet and nickel mesh, were designed for operating under submerged conditions and depending only on dissolved oxygen. Therefore, air aeration is not required. The proposed air cathode was capable of sustaining a discharge current of 1 mA for 42 days (1008 mAh) under submerged conditions thus supporting its viability. Aside from the low-cost design, the cylindrical air cathode configuration also offers the advantage of compact multipolar design. Since the microbial zinc/air cell was fed with lignin rich EFB as a substrate for Phanerochaete chrysosporium, this work assessed its efficacy as a lignin rich agrowaste degradation cell. The rates of lignin degradation were evaluated under self-generated current and externally supplied current. It was found that electric current stimulus enhances the lignin degradation. Externally supplied current induced higher lignin degradation. However, when the current supplied was 5 mA or higher, it disrupted the lignin degradation rates.