Navid Moheimani

Microalgal and macroalgal phytoremediation has been proposed as a practical green solution for the treatment of anaerobically digested piggery effluent (ADPE). This is mainly due to the algae’s inherent ability to strip away and convert inorganic nutrients, especially nitrogen and phosphorous efficiently from various effluents. Our previous Pork-CRC (4A-106 and 4A-108) studies showed the potential of a microalgae consortium that could grow efficiently on undiluted ADPE (up to 1600 mg L-1 of ammonium) and that of a macroalgae consortium (4A-107) which could treat diluted ADPE (below 250 mg L-1 of ammonium). The main advantage of macroalgae over microalgae is their ease of harvest, especially if the aim is to use the generated biomass as a source of animal feed. There is a potential in co-culturing cultures of microalgae and macroalgae to increase the overall efficiency of ADPE treatment and improve the economics related to algal biomass production. In accordance, we evaluated the co-cultivation of both microalgae and macroalgae together in two distinctive studies. For both studies, previously isolated consortium of microalgae consisting of Chlorella and Scendesmus sp. was initially grown on undiluted ADPE until the concentration of ammonium was reduced to desired levels. In order to identify the most suitable and efficient macroalgal species for co-cultivation with microalgae, a preliminary study was conducted to evaluate the growth and nutrient removal of four locally isolated macroalgae on ADPE. In the first co-cultivation study, the ADPE grown microalgae was directly utilized as a cultivation media for the propagation of macroalgae (Cladophora sp.) which was found capable of growing in ADPE up to 150 mg L-1 NH4+. However, despite the different conditions evaluated, the growth and photo-physiology of Cladophora sp. was found to decline and eventually led to its death due to the dominancy of microalgal culture during the co-cultivation period. Subsequently, based on this outcome, an outdoor inclined reactor was customized to evaluate the potential use of attached macroalgal culture as a way of scrubbing available nutrients and microalgae biomass from ADPE post microalgal treatment. Although, the inclined system was very efficient in scrubbing and harvesting microalgae biomass, nevertheless, nutrient removal rates (i.e. ammonium and nitrate) of the co-cultivated system was much lower than the control which was operated using macroalgae only. In this work, despite multiple different approaches and cultivation systems, both algal groups were unable to co-exist for efficient growth in ADPE due to direct competition for available resources and the negative interaction of both algal groups. Nevertheless, through this study, it has been demonstrated that macroalgae could be potentially used for harvesting microalgae grown in ADPE.

Anaerobic digestion piggery effluent (ADPE) has high ammonium content (toxic to most organisms) and is very turbid. The environmental consequences of high productivity piggeries is significant and can result in negative environmental impacts, hence bioremediation techniques (in particular using macroalgae) are therefore of great interest. In this study, we evaluated the growth potential of several locally isolated macroalgae in ADPE under outdoor climatic conditions and investigated their nutrient removal rates and biochemical composition. A consortium of two macroalgae, Rhizoclonium sp. and Ulothrix sp. was isolated and could efficiently grow in the ADPE with concentration of up to 248.4 mg NH3. N L-1. Macroalgal consortium growth could not be maintained at higher ADPE concentration. Maximum ammonium removal rate (30.6 ± 6.50 mg NH4+-NL-1d-1) was achieved at ADPE concentration equivalent to 248.4 mgNH4+-NL-1. Mean biomass productivity of 31.1 ± 1.14 g AFDW m-2d-1 was attained. Total carbohydrate and protein contents ranged from between 42.8-54.8 and 43.4-45.0% (ash-free dry weight), respectively, while total lipid content was very low. Our findings highlight the potential use and promise of Rhizoclonium and Ulothrix sp. consortium for the bioremediation of ADPE and biomass production. To the best of author’s knowledge, this is the first study evaluating the potential of using macroalgae to treat ADPE. While there is a need for further optimisation, successful macro algae growth on ADPE indicates the potential of using these organisms for not only treating ADPE but also as a potential source of animal feed or bioenergy production.

The purpose of this study was to identify the best locations for constructing commercial-scale algae-to-biofuel production facilities in Western Australia (WA). The following document provides an overview of the study identifying a GIS modelling approach to locate optimal locations for production. Chapter one sets the context for the study positing algal biofuel manufacturing within the rubric of global renewable energy production. Chapter two focuses on methods used for site targeting in general, followed by a more specific discussion of site targeting approaches used to identify appropriate locations for algal biofuel production facilities. Chapter three outlines the area under study as well as the specific methods used to develop the GIS based site targeting model. Chapter four provides the results of the analysis followed by general conclusions in Chapter five.