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Item Increasing liquid fuel self-sufficiency in Indonesia through utilization of marginal land and appropriate technology for biofuel production : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Energy Management, Massey University, New Zealand(Massey University, 2019) Lamria, MaslanThis study proposed a strategy for increasing self-sufficiency of liquid fuel in Indonesia. The novel approach not previously undertaken was to integrate the utilization of marginal land with innovative technology for drop-in biofuel (DBF) production. The strategy involves interdependent relationships, so a systems dynamics modelling approach was applied. The assessments generally cover the national scope, but also specifically used Sumba Island as a case study around the marginal land issue. From a number of potential energy crops considered for growing on Sumba Island, Pongamia pinnata was selected. Metal soap decarboxylation was chosen as the preferable conversion technology for this oil crop, even though it has not yet reached full commersialisation. A simulation framework was developed to explain the intrinsic interrelationship between elements. These comprised the preparation of feedstock from marginal land, preparation of more appropriate conversion technology, a liquid biofuel supply system, and liquid fuel import demands. A delay in any of the elements causes a delay in DBF uptake, and thus time becomes a crucial factor. Considering the time factor, this study assessed the political dimension of sustainability, which is lacking in other bioenergy studies. A model, Assessment Tool of Biofuel Strategy through Utilization of Marginal Land and Innovation in Conversion Technology (ABMIC) was developed to test the strategy outcomes in some priority sustainability indicators. The model consists of ten sub-models containing two feedback loops invented in this study: a) between the “sense of urgency for action by the President” (SU) and liquid biofuel supply and demand; and b) between the conventional biofuel production from palm oil and the DBF production. The ABMIC model was tested and validated for structural validity, behaviour validity, and model usefulness. The results from scenario-based simulations confirmed that a systems dynamics approach was suitable for assessing the strategy. It supported the hypothesis that a political element, namely SU level, critically affects the success in implementing a liquid biofuel strategy through marginal land use and conversion technology innovation to increase liquid fuel self-sufficiency, which in turn influences the political element itself. An increase in SU level leads to a significant increase in liquid fuel self-sufficiency, foreign exchange saving, gross regional domestic product, and CO2 emissions reduction. SU should be sustained by maximizing future vision intervention. With modifications, the SU structure could be applied in non-biofuel sectors. Finally, this study outlines opportunities for further research to improve the model including through disaggregation, endogenizing variables, building functions of effects between variables, improving the variable quantifications, and further exploration of the variables.Item Enhancing harvestable algal biomass production in wastewater treatment high rate algal ponds by recycling : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Environmental Engineering at Massey University, Palmerston North, New Zealand(Massey University, 2013) Park, Byung KwanHigh Rate Algal Ponds (HRAPs) are an efficient and cost-effective system for wastewater treatment and produce algal biomass which could be converted to biofuels. However, little research has been conducted to improve harvestable biomass production from these ponds. Laboratory and small-scale outdoor research reported in the literature indicates that selective biomass recycling is partially effective at controlling algal species in HRAP. This, therefore, offers the potential to select and maintain a rapidly settleable algal species. To date, algal species control of similarly sized, co-occurring algae has not been demonstrated in wastewater treatment HRAPs. Furthermore, the influence of algal recycling on biomass harvest efficiency, harvestable biomass productivity, net biomass energy yield and the growth of the dominant algal species in the HRAPs have never previously been investigated. The main hypothesis of this Ph.D. was: ‘Recycling a portion of gravity harvested biomass (‘recycling’) back into the HRAP improves harvestable biomass production’. To test this, a series of experiments was conducted using pilot-scale wastewater treatment HRAPs, outdoor mesocosms and laboratory microcosms. Firstly, the influence of recycling on species dominance and biomass harvest efficiency was investigated using two identical pilot-scale HRAPs over two years. This pilot-scale study showed that recycling promoted the dominance of a rapidly settling colonial alga, Pediastrum boryanum, and maintained its dominance over the two year experimental period. Moreover, P. boryanum dominance was relatively fast to establish and was then stable and sustainable between seasons. The higher dominance of P. boryanum in the HRAP with recycling improved biomass harvest efficiency by gravity sedimentation from ~60% in the control HRAP without recycling to 85%. Unexpectedly, recycling also improved the ‘in-pond’ biomass productivity by 20%. The combination of the increased biomass productivity of the HRAP and the increased biomass harvestability with recycling improved the ‘harvestable biomass productivity’ by 58%. Overall, recycling increased the net biomass energy yield by 66% through the combined improvements in biomass productivity, harvest efficiency and a small increase in algal biomass energy content. To determine the reproducibility of these findings and investigate the mechanisms responsible, twelve outdoor mesocosms were studied. This mesocosm research repeatedly confirmed that recycling can establish P. boryanum dominance, and improve biomass productivity and settleability. Settleability was not only found to be improved by recycling the ‘solid’ fraction of the harvested biomass but also by recycling of the ‘liquid’ fraction, potentially indicating the presence of extracellular polymeric substances. Several possible mechanisms to explain the increase in biomass productivity were identified. However, after review all but two were discounted: (i) the mean cell residence time (MCRT) was extended thereby increasing the algal concentration and thus allowing better utilization of incident sunlight; and (ii) the relative proportion of algal growth stages (which may have different net growth rates) was shifted, resulting in an increase in the net growth rate of the algal culture. To investigate these mechanisms further, the life-cycle of P. boryanum was studied in detail and showed, for the first time in the literature, that its net growth rate does indeed vary between the three life-cycle stages (‘growth’ > ‘juvenile’ > ‘reproductive’). Given that the mesocosm studies in Chapter 4 showed that recycling increased the number of growth colonies by ~2-fold and juvenile colonies by ~4-fold then it is proposed that mechanism (ii) does appear to be viable. This Ph.D. work has demonstrated that recycling a portion of gravity harvested biomass could be a simple and practical method to enhance biomass productivity, harvest efficiency and energy content, which contribute to achieve higher ‘harvestable biomass productivity’ and ‘energy yield’ in wastewater treatment high rate algal ponds.Item Photobioreactor production of microalgae for potential fuel oils : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biotechnology at Massey University, Palmerston North, New Zealand(Massey University, 2013) Luangpipat, TiyapornThis work focussed on a detailed characterization of the freshwater microalga Chlorella vulgaris as a producer of potential fuel oils. Uniquely, growth and oil production of C. vulgaris were characterized in full strength seawater-based media, something that has not been previously reported. C. vulgaris was selected for a detailed study after a screening of six potential oil producing microalgae. For photoautotrophic growth, always under carbon sufficiency and at normal growth temperature, the characterization study covered: the biomass growth rate; lipid content in the biomass; productivities of the lipids and the biomass; the biomass loss in the dark; the lipid/biomass yields on macronutrients; and the energy content of the biomass. The above key production parameters were characterized in a purpose-built tubular photobioreactor (~80 L) and in stirred tank photobioreactors (~7.5 L) under conditions of nitrogen sufficiency and at various levels of nitrogen limitation. Production was evaluated in both batch and continuous cultures at various dilution rates using indoor light to mimic sunlight. The production temperature mimicked the relatively warm conditions that would be encountered in a potential production system located outdoors in a tropical climate. In seawater media at 25–27 °C, C. vulgaris was shown to have a crude oil productivity of >37 mg L⁻¹ d⁻¹ and the energy content of the biomass could exceed 25 kJ g⁻¹, depending on the culture conditions. Both these values were high compared with the reported data for this alga in freshwater media. Compared with continuously illuminated culture, day–night cycling of irradiance reduced oil productivity by ~31%, but the energy content of the biomass were reduced by only about 8%. In seawater, the alga could be grown as rapidly and stably as in freshwater. The lipid content of the biomass commonly exceeded 30% by dry weight and in exceptional cases a lipid content of more than 50% (by weight) was achieved. Biomass calorific values of ≥27 kJ g⁻¹ could be attained in some cases. Nitrogen starvation enhanced the lipid contents of the biomass by >3-fold relative to the lipid contents for the nonstarved case. Steady-state continuous cultures were shown to be possible. Both batch and continuous operations were feasible, especially in stirred tanks, but the culture was more failure prone, or relatively less productive, in the tubular photobioreactor.Item Improving soluble chemical oxygen demand yields for anaerobic digester feedstock using leaching : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Environmental Engineering, School of Advanced Technology and Engineering, College of Sciences, Massey University, Palmerston North, New Zealand(Massey University, 2012) Ralphs, John LeonardWaste biomass is often a liability to many municipalities. Technologies exist that can turn this biomass into energy which can then be sold. Anaerobic digestion is one of the important technologies that utilises this biomass to turn it into biogas. One of the factors that affects the rate that biogas can be produced is the speed that suitable organic compounds can be delivered to methanogenic microorganisms. These organic compounds such as sugars and amino acids are released from plant material at different rates depending on their availability. A portion of the compounds are readily soluble in water and are immediately available, some of the compounds are locked up inside the plant cells and some of the compounds such as cellulose are not soluble and need to be hydrolysed into sugars before they can be converted into methane. Hydrolysis is usually the rate limiting step in anaerobic digestion. Leaching of green waste was investigated as a form of pre-treatment to externalise the initial stages in anaerobic digestion that makes soluble organic compounds available for the consecutive mthanogenic stages of anaerobic digestion. The added benefit of leaching is it removes the complexity of solids handling from inside anaerobic digester. Many various forms of leaching technologies that are coupled to anaerobic digesters have been trialled with grass and silage, little research was found on leaching green waste and few trials had used the simplified unheated flooded tank system as tested here. Pilot and laboratory leaching trials were conducted on shredded green waste as well as grass clippings to establish the efficiency of leaching by measuring the COD yields in the leachate. Additionally, rumen contents from cattle rumen were added to grass clippings in order to investigate if the leaching efficiency from the grass could be improved. Leaching was tested at a pilot scale in an open to the air reactor tank in ambient temperature in a temperate climate. Hydraulic retention times ranging from 4 hours to 7 days were tested to establish the most effective leaching strategy. The laboratory trials were conducted with the temperature controlled at 25°C to simulate ambient environmental conditions in a temperate climate. The effect of storing feedstock was tested to see how changes in handling times affected the process. Gas production from the leachate was tested using 2 L CSTR (Continuously Stirred Tank Reactor) anaerobic digesters to confirm the usability of the leachate as a feedstock in an anaerobic digester. Pilot scale trials of shredded green waste and grass clippings gave maximum COD concentrations of 5.4 ± 0.5 and 47±4 g COD / L of leachate respectively. Pilot trials of shredded green waste and grass leachate reached a maximum total COD yields of 53 ± 2 and 410 ± 20 kg COD / tonne VS respectively. Laboratory scale trials of shredded green waste and grass clippings gave maximum COD concentrations of 7.0 ± 0.1 and 49 ± 2 g COD / L of leachate respectively. Laboratory trials of shredded green waste and grass leachate reached a maximum total COD yields of 132 ± 8 and 410 ± 20 kg COD / tonne VS respectively. Laboratory trials are indicative of how pilot trials will behave and differences are likely to be due to an increased bulk density in solids in pilot trials. Shredded green waste and grass leachate gave maximum 3.7 and 7.8 g BOD / L respectively. Nutrients in the leachate were tested: nitrogen levels in shredded green waste and grass leachate reached maximum levels of 51 and 460 mg / L respectively; DRP (Dissolved Reactive Phosphorus) levels in the shredded green waste and grass leachate reached maximum levels of 6 and 85 mg / L respectively. The leaching tanks produced gas while leaching was taking place; a sample of this gas was captured and the levels of CH4, CO2 and H2 were measured as 0%, 25.5% and 5.0% respectively. Gas production from anaerobic digestion of shredded green waste and grass in a CSTR at 35°C produced 0.23 ± 0.01 and 0.534 ± 0.005 m3 biogas / kg COD respectively. Use of grass that is fresh gives much higher yields of dissolved organic compounds in the leachate than when the grass is stored in covered area for 30 days. Leaching grass with an HRT (Hydraulic Retention Time) of 1 day gave optimal results in terms of concentration and yields of dissolved organic compounds in the leachate compared to leaching trials with an HRT of 4 hours or 7 days. Green waste gave much lower concentration and yields of COD than grass and an HRT of 7 days was the most suitable for gaining the best concentration and yield of dissolved organic compounds compared to a 4 hour or 1 day HRT. The overall mass transfer of organic compounds when leaching freshly shredded green waste is most likely limited by a combination of hydrolysis and the rate that soluble compounds are released from within plant cells as the cell membranes degrade. In trials of fresh and stored grass and stored shredded green waste, shortening the HRT increases the total yield of dissolved organic compounds leached into the leachate; however, this is at the expense of increased concentrations of dissolved organic compounds within the leachate. The lower leachate concentrations with the shorter HRTs means that the leachate is less suitable to uses as a feedstock for an anaerobic digester. Anaerobic digestion of grass leachate produced much more biogas / kg COD than anaerobic digestion of shredded green waste leachate, this may be a result of an inhibiting compounds such as tannins, additionally to this the material that the shredded green waste is composed of will have higher levels of lignocellulose materials that are not readily soluble. The leachate was found not to degrade when stored at 25°C in an open top container, this maybe a result of low pH inhibiting degrading micro-organisms, this has significant benefit as the leaching process can be separated from the anaerobic digestion process without degrading the quality of the leachate while it is being stored.