The cost of microalgae harvesting constitutes a heavy burden on the commercialization of biofuel production. The present study addressed this problem through economic and parametric comparison of electrochemical harvesting using a sacrificial electrode (aluminum) and nonsacrificial electrode (graphite). The harvesting efficiency, power consumption, and operation cost were collected as objective variables as a function of applied current and initial pH of the solution. The results indicated that high harvesting efficiency obtained by using aluminum anode is achieved in short electrolysis time. That harvesting efficiency can be enhanced by increasing the applied current or the electrolysis time for both electrodes materials, where 98% of harvesting efficiency can be obtained. The results also demonstrated that the power consumption with graphite anode is higher than that of aluminum. However, at 0.2 A the local cost of operation with graphite (0.036US$/m3), which is distinctly lower than that of aluminum (0.08US$/m3). Furthermore, the harvesting efficiency reached its higher value at short electrolysis time at an initial pH of 6 for aluminum, and at an initial pH of 4 for graphite. Consequently, the power consumption of the harvesting process could be reduced at acid- nature conditions to around 0.46KWh/Kg for aluminum and 1.12KWh/Kg for graphite.

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Two modes of electrochemical harvesting for microalgae were investigated in the current work. A sacrificial anode (aluminum) was used to study the electrocoagulation-flotation process, and a nonsacrificial anode (graphite) was used to investigate the electroflotation process. The study inspected the effect of chloride ions concentration and the interelectrode distance on the performance of the electrochemical harvesting processes. The results demonstrated that both electrodes achieved maximum harvesting efficiency with a 2 g/L NaCl concentration. Interestingly, by increasing the NaCl concentration to 5 g/L, the harvesting efficiency reduced dramatically to its lowest value. Generally, the energy consumption decreased with increasing of NaCl concentration. Moreover, the energy consumption achieved with aluminum anodes is lower than that achieved with graphite. However, by increasing the gap between the electrodes from 15 mm to 30 mm, the time required to achieve the maximum efficiency doubled, and energy consumption increased consequently.

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In this study, the development of a new generic feedstock manufacturing technique based on SSF, which was then applied to the succinic acid fermentation process. Separation of the wheat was accomplished using milling and gluten extraction techniques. This waste product from wheat milling, known as bran, was used to manufacture glucoamylase and protease enzymes using Aspergillus oryzae and Aspergillus awamori. A total of 140 g l 1 glucose and more than 3.5 g l 1 free amino nitrogen were produced after hydrolysis of both the gluten-free and gluten-containing solutions. These two sources, when combined, supplied all the nutrients required for succinic acid fermentation mediated by Actinobacillus succinogenes. A fermentation employing just the mixed hydrolysate streams yielded about 22 g l 1 succinic acid. With the addition of MgCO3 to the wheatderived medium, succinic acid production rose to 64 g l 1. Using the SSF-based technology, it was possible to create a generic wheat feedstock that could be utilised to make succinic acid and then demonstrate the effectiveness of the proposed methodology.