Almost80% of energy consumed across the world comes from fossil fuels [1]. Biofuels are a promising solution to ween the world off its addiction to petrochemicals. Where do biofuels come from? Municipal wastewater containas an array of organic pollutants which must be removed before being discharged into the aquatic environment. The use of microalgae culture is an attractive solution to remove these pollutants. They undergo photosynthesis to produce oxygen used by aerobic bacteria to biodegrade pollutants, while simultaneously consuming carbon dioxide released from bacterial respiration [2]. As they grow, the algal biomass can be utilized for energy recovery (biofuel production), and for producing valuable substances for feed, food, nutraceutical, and pharmaceutical industries [3]. Interest in the production of biofuels has gained momentum in recent years as they provide a `green' alternative to exhaustible and environmentally unsafe fossil fuels.
We investigate the optimal level of algae to be harvested such that the yield is maximised whilst simultaneously maximising the removal of nutrients from the wastewater. We use steady-state analysis to study the standard wastewater treatment model [4] while including a `light term' for self-shading of algae. There has been very limited research integrating a `light term' into pre-existing algae growth models [5]. Harvesting of algae must be conducted at a sustainable rate. If too much algae are harvested, the level of organics in the effluent will exceed the allowable limits imposed by legislation and we risk driving them to extinction. If too little algae are harvested, there is no product to be converted into biofuels.