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Faculty of Applied Sciences

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Author: search.filters.author.Ranjith Kumar, R.

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    Physico-chemical and biotic factors influencing microalgal seed culture propagation for inoculation of a large scale raceway pond
    (African Journals Online, 2014) Mutanda, Taurai; Ranjith Kumar, R.; Bux, Faizal
    The growth of Chlorella vulgaris in open pond aquatic conditions poses serious challenges due to the interplay of both physico-chemical and biotic factors. We report here the monitoring of physico-chemical and biotic parameters affecting the propagation of C. vulgaris seed culture for inoculation of a large scale raceway pond (300 000 L capacity) in South Africa. The C. vulgarisstrain used for this purpose was isolated from a wastewater maturation pond and characterized for its potential for biomass and lipid production. The isolate was grown aseptically in 4 × 25 L aspirator bottles in BG-11 medium under ambient laboratory conditions and the culture was supplied with filtered air and exposed to 200 µmol photons per m2 per second using Gro-Lux agricultural fluorescent lights. The culture was transferred to a 500 L capacity portable pool under open conditions. This pond was used to further inoculate 3 more portable ponds. Physico-chemical and biotic growth parameters were monitored on a daily basis in the three ponds. The over reliance on fossil fuels will have a major impact on power supply in the near future if renewable sources of energy are not developed at a fast pace. The developed inoculum was subsequently used to inoculate an open raceway pond for large scale biomass production for biodiesel production.
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    Biodiesel from microalgae: A critical evaluation from laboratory to large scale production
    (Elsevier, 2013) Rawat, Ismail; Ranjith Kumar, R.; Mutanda, Taurai; Bux, Faizal
    The economically significant production of carbon-neutral biodiesel from microalgae has been hailed as the ultimate alternative to depleting resources of petro-diesel due to its high cellular concentration of lip-ids, resources and economic sustainability and overall potential advantages over other sources of biofu-els. Pertinent questions however need to be answered on the commercial viability of large scale production of biodiesel from microalgae. Vital steps need to be critically analysed at each stage. Isolation of microalgae should be based on the question of whether marine or freshwater microalgae, cultures from collections or indigenous wild types are best suited for large scale production. Furthermore, the determination of initial sampling points play a pivotal role in the determination of strain selection as well as strain viability. The screening process should identify, purify and select lipid producing strains. Are natural strains or stressed strains higher in lipid productivity? The synergistic interactions that occur nat-urally between algae and other microorganisms cannot be ignored. A lot of literature is available on the downstream processing of microalgae but a few reports are available on the upstream processing of mic-roalgae for biomass and lipid production for biodiesel production. We present in this review an empirical and critical analysis on the potential of translating research findings from laboratory scale trials to full scale application. The move from laboratory to large scale microalgal cultivation requires careful plan-ning. It is imperative to do extensive pre-pilot demonstration trials and formulate a suitable trajectory for possible data extrapolation for large scale experimental designs. The pros and cons of the two widely used methods for growing microalgae by photobioreactors or open raceway ponds are discussed in detail. In addition, current methods for biomass harvesting and lipid extraction are critically evaluated. This would be novel approach to economical biodiesel production from microalgae in the near future. Glob-ally, microalgae are largest biomass producers having higher neutral lipid content outcompeting terres-trial plants for biofuel production. However, the viscosities of microalgal oils are usually higher than that of petroleum diesel.
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    Improving the feasibility of producing biofuels from microalgae using wastewater
    (Taylor and Francis, 2013-10-08) Rawat, Ismail; Bhola, Virthie; Ranjith Kumar, R.
    Biofuels have received much attention recently owing to energy consumption and environmental concerns. Despite many of the technologies being technically feasible, the processes are often too costly to be commercially viable. The major stumbling block to full-scale production of algal biofuels is the cost of upstream and downstream processes and environmental impacts such as water footprint and indirect greenhouse gas emissions from chemical nutrient production. The technoeconomics of biofuels production from microalgae is currently unfeasible due to the cost of inputs and productivities achieved. The use of a biorefinery approach sees the production costs reduced greatly due to utilization of waste streams for cultivation and the generation of several potential energy sources and value-added products while offering environmental protection. The use of wastewater as a production media, coupled with CO2 sequestration from flue gas greatly reduces the microalgal cultivation costs. Conversion of residual biomass and by-products, such as glycerol, for fuel production using an integrated approach potentially holds the key to near future commercial implementation of biofuels production.