Добірка наукової літератури з теми "Green Algae Cultivation"

Rice is a prime food crop for Asian countries. Wet land rice cultivation contributes maximum grain yield than dry land rice. Cauvery delta is a predominant area for rice cultivation in Tamil Nadu. Green algae growth during Kuruvai (June -August) season is a serious problem in wet land rice. These algae growth create anaerobic condition and prevent rice root respiration. The entire rice root was uprooted and floated on the stagnated water during initial stage. There is no preliminary study for green algae control in rice field. Soil and water samples were collected and analyzed for the nature of occurrence. Laboratory and field experiments were conducted to find out the remedial measures. The results of soil and water sample analysis showed that use of bore well water and dumping of phosphatic fertilizers leads to salt accumulation which favours the green algal growth. The results of the laboratory experiment revealed that the CuSO4 londox power, propiconazole and hexaconazole showed moderate inhibition on 5th day after treatment. The findings from field experiment indicated that use of conoweeder, alternate wetting and drying and CuSo4 drenching @ of 2.5 kg/ha when green algae appearance has just noticed or 5.0 kg/ha when severe growth occurred was effective in managing the green algae. Among all measures, alternate wetting and drying is the best management practices. CuSO4 drenching reduces around 70% of the growth. Even though CuSO4 react negatively with algae growth, soil pH changes and salt concentration play a major role on the CuSO4 action towards green algae. In order to maintain soil health condition, biofertilizer application, crop rotation, green manure trampling to be practised to recover the soil from alkaline pH, removal of accumulated salt and to control the algae growth using CuSO4.

The implementation of algal systems as a viable wastewater treatment option has been seriously limited by the availability of cost effective techniques for removing algae from the effluent stream. In this study, the problem of biomass separation was overcome by the selective cultivation of algae species which could be removed effectively by simple screening. The selection of desired species was achieved by a combination of short hydraulic space time and various size micro-screens operating as algae selectors on the effluent stream. A high rate algae growth system, in which the mean cell residence time and hydraulic space time could be manipulated independently, was developed. With humus tank effluent as feedstock, a hydraulic space time of 10 hours and a 200 µm opening size crossflow-microscreen, the filamentous green algae, Stigeoclonium, became the dominant species. This selected culture could be readily maintained at any predetermined concentration in the system with less than 20 mg/ℓ suspended solids in the effluent. The biomass produced was exceptionally easy to harvest.

AbstractThe cyanobacterium Synechocystis aquatilis was observed growing as a monospecies in enriched phytoplankton samples in the laboratory, indicating its allelopathic activity on coexisting phytoplankton species. Therefore, the present study screened the culture medium of an axenic strain of this cyanobacterium for the presence of allelechemicals with algicidal properties by thin-layer chromatography (TLC). The allelopathic effect of S. aquatilis was evaluated by co-cultivation of target species of toxic cyanobacteria and green algae with this cyanobacterium, as well as by evaluation of norharmane (β-carboline 9H-pyrido(3,4-b) indole) crude extract prepared from the culture medium of Synechocystis. The growth of target algal species was measured as a cell density after 6 days incubation. The results showed that S. aquatilis produced the indole alkaloid norharmane with large quantities in the culture medium (86 μg l−1). In co-cultivation experiments, S. aquatilis inhibited the growth of all tested cyanobacteria and green algae. Norharmane crude extract exhibited stronger inhibition of cyanobacteria (EC50 = 4.6–4.8 μg ml−1) than green algae (EC50= 6.3–6.4 μg ml−1) in a concentration-dependent manner, indicating its apparent role in the allelopathic activity of S. aquatilis. The possible applicability of the allelochemical, norharmane, as an algicide to prevent the formation of harmful algal bloom was discussed.

Algal biomass is a prospective feedstock for the eco-sustainable production of many different products with added value, such as meals, feeds, and fuels. The remaining biomass from the algae can be used as raw material and can be transformed into useful secondary products after the important macromolecules have been removed. By optimizing algal biomass hydrolysate utilizing microbial fermentation, several studies demonstrated the generation of bioenergy (bioalcohol, biogas, and biohydrogen) and biochemicals (organic acids and biopolymers). Since the harvest and maintenance of sustainable algal cultivation incur considerable energy and economical prowess, developing products from algae remains a challenge to be countered in commercial applications. This is a typical bottleneck issue when processing algae for fuels or chemicals at the pilot scale. Implementation of integrated algae biorefinery methods can substantially reduce the cost of production and energy consumption. An algae-based green economy can be financially more viable and utilizable, especially for countries with weaker economies. This review’s goal is to examine the implementation of integrated biorefineries for the recovery of bioproducts generated from algae and potential applications. In this context, the life cycle analysis and business elements of a unified algal biorefinery are also addressed.

<p>This study examines CO2 for the growth of green microalgae by cultivating algal strains in a tank type reactor or fermentor. The study included optimization of the productivity of green algae in the capture of CO2 which can be used as a greenhouse gas catcher. Green algae were isolated from several waters in Banda Aceh and Aceh Besar. The microalgae species of this isolation and its identified species were subsequently cultivated in a tank-shaped cultivation (cultivation) container with 4 flourescent lamps (2x8 watts; 4x8 watts) installed on the outside side of the tank. This study evaluated the comparison of the growth of aerated microalgae O2 (1.25 liters / minute) with fixation of CO2 (1 and 2 liters / minute). The capture of CO2 into carbon dioxide is done by looking at the growing biomass, and the yield content of oil in biomass. The results showed that there were significant differences in the growth patterns of microalgae given O2 aeration and CO2 fixation. Modified &amp; CHU 13 Detmer Modified media does not provide a significant difference to algal growth. With a large intensity of light with a medium that is sufficient to increase the growth of microalgae until it reaches the death phase. Component analysis by Chromatography Gas Mass Spectrometry (GC-MS) shows that the largest component in vegetable oils from green microalgae is Palmatic acid (9.36%), Thiogeraniol (24.63%), Cyclopropane Methanol (2.45%), Farnesol ( 2.39%), Trimethyl (2.78%) and Dodencadien (5.06%).</p><p> </p>

The influence of some abiotic factors on the cultivation of biotechnologically significant algae cultures is considered on the example of Chlorococcum sp. with the selection of the optimal nutrient medium, its modification in order to maximize the growth of microalgae biomass and reduce the cost of their cultivation process. During the experiment, the medium for algae cultivation was modified, which had different parameters from the classical Prata medium, giving more intensive growth of algae and economic advantages of growing Chlorococcum sp. Keywords: GREEN ALGAE, PRODUCTIVITY, CHLOROCOCCUM SP., PRATA MEDIUM

Blue green algae play an important role in thefixation of atmospheric nitrogen in the rice fields.Recent researches have shown that blue green algaecan be used as biofertilizers for rice cultivation(Venkataraman, 1977). In this paper we describe theinfluence of algae as manure on the yield andcomposition of Linseed plant.

Wastewater treatment and recycling using Spirulina algae have become increasingly popular in recent years due to its potential to address a range of environmental and nutritional challenges (3). The primary objective of this approach is to use wastewater as a nutrient source for Spirulina algae cultivation and then harvest the algae as a feed for both Plants and animals. In this Research, we will discuss in detail the various objectives of wastewater treatment recycling using Spirulina algae and how it can help promote sustainable development(3). One of the primary objectives of using Spirulina algae to treat wastewater is to promote environmental sustainability(1). Wastewater treatment is crucial to reducing the environmental impact of untreated wastewater, which can harm aquatic life and pollute water bodies. By using Spirulina algae as a means of treating wastewater, we can reduce the level of harmful pollutants in the water and promote a healthier ecosystem(2). Spirulina algae can absorb and metabolize a range of contaminants, including nitrogen and phosphorus, which are often found in wastewater. As a result, using Spirulina algae for wastewater treatment can help reduce the level of pollutants released into the environment, ultimately promoting a more sustainable and healthier ecosystem. Another significant objective of using Spirulina algae to treat wastewater is to promote nutritional benefits. Spirulina is a highly nutritious food source that is rich in protein, vitamins, and minerals.(4) By cultivating Spirulina using wastewater and then using the harvested algae as a food source, we can provide a sustainable and nutritious food source that can benefit both human health and the environment. Spirulina has been shown to have numerous health benefits, including reducing inflammation, boosting the immune system, and improving digestive health. Additionally, Spirulina is an excellent source of protein, making it an ideal food source for vegetarians and vegans. Moreover, the use of Spirulina algae for wastewater treatment and recycling can help promote economic development.(5) Spirulina cultivation can be a profitable business opportunity, particularly in areas where water and other resources are scarce. (6)Additionally, the use of Spirulina algae for wastewater treatment can help reduce the costs associated with traditional wastewater treatment methods. As a result, using Spirulina algae for wastewater treatment and recycling can create new economic opportunities while also promoting sustainable development.

Volatile substances of the green microalga Scenedesmus incrassatulus, cultivated in fresh and salt water, were studied. Cultivation in fresh water diversifies volatile secondary metabolites. Hydrocarbons and derivatives of the acetate pathway predominate when algae are grown in salt water; isoprenoids and aromatics are more abundant after fresh water cultivation.

Abstract The reactive oxygen nitrogen species (RONS) from plasma activation is intensively used in agriculture, particularly in the regulation of seeds germination and plants growth. It shows a promising effect on increasing the germination rate and promoting the growth of plants. This research employed plasma activated water (PAW) in cultivation of green algae (Chlorella spp.). The objective of this research was to introduce a comparison between the use of different fluids for cultivation of green microalgae. The experiment was carried out using cultivation of green microalgae in different fluids which were fertilized water, simulated-fertilized water, tap water, tap water treated with activated plasma for 2.5, 5.0 and 7.5 minutes. Samples of green microalgae were cultivated in these waters for 7 days. A comparative investigation was then conducted. It was found that nitrates remained constant at 10 mg/L on all treatment times, while the concentration of hydrogen peroxide considerably increased with the treatment time. According to the growth of green algae, a better result than simulated-fertilized water and tap water. This indicates an effect of RNS on promoting the growth of green algae. Upon completion of the test, the fertilized water showed the highest growth. However, a well-controlled plasma activation would make PAW possible for industrial uses in the future.

碩士
逢甲大學
環境工程與科學所
99
Many countries have been devoted to study biofuels for the substitution of fossil fuels. Studies were mainly concentrated and focused on studying the biodiesel and the oil-producing algae. The aim of this study is to find the optimal culture conditions of fresh water green algae (Chlorella protothecoides, C. vulgaris, Ourococcus sp., Scenedesmus obliquus, and S. dimorphus) in view of their possible utilization as novel feedstock for biodiesel production. At the same time, the Nile red method is used to quantify the lipid content in the oil-producing algae. The results showed the optimal culture conditions for C. protothecoides, Ourococcus sp. and S. dimorphus were at an air flow rate of 1.0 L/L．min, light intensity of 95 μmol/m2s (7000 Lux) and a continuous light cycle (light: dark, 24:0, h). The optimal culture conditions for S. obliquus and C. vulgaris were similar to what mentioned above, the only difference for S. obliquus was the light intensity of 143 μmol/m2s (10500 Lux); and the air flow rate was 2.0 L/L．min for C. vulgaris. Under the optimal culture conditions, algae growth rate were 1.8 - 3.1 times fast than statically cultured, with 2.2 - 4.4 days of reduction in generation time, and an increase of 1.6 - 8.2 times biomass.After seven day-cultured in optimal condition, the lipid in algae ranged from 28.5% to 42.7% (w/w) by Nile red method and from 14.5% to 36.2% (w/w) by gravimetric method. These results revealed that neutral lipid content determined by Nile red method was higher than that by gravimetric method. Additionally, Nile red method was more efficient to perform than gravimetric method. Therefore, the gravimetric method was used to determine lipid content of five algae and S. dimorphus had the highest lipid yield, which may make it an ideal source of biodiesel.

Research Doctorate - Doctor of Philosophy (PhD)
Algae as a potentially sustainable source of fuel, feed and nutraceuticals has led to interest in the algae biorefinery concept for production of sustainable products. The cultivation of algae has several advantages as algae can grow in non-potable water and in non-arable land and can sequester CO₂ from flue gas. In addition, different components of the algae produce different value-added products such as biodiesel, which is obtained from TAGs, bioethanol from starch and animal feed from functional biomass. However, there is a lack of commercial viability for photosynthetic algae due to limitations in biomass productivity and the capacity to optimise the chemical composition of the algae, both of which are caused by suboptimal nutrient loading and low light conditions. Therefore, this thesis aims to understand how to optimise the production of the individual biochemical algae components, namely, starch, TAGs and functional biomass by modelling batch photosynthetic cultures. Special attention was given to the influence of external nitrogen and light conditions on composition kinetics. The primary species studied in this thesis is Chlorella vulgaris for varying nitrogen load and Scenedesmus obliquus for varying light flux. Biochemical measurements on S. Obliquus for different light conditions were reported and compared with the simulation model. Finally, trial experiments on the effect of glucose relative to a photosynthetic control on algal growth were also performed on Nannochloropsis oculata and Tetraselmis Chuii. A review of algal composition modelling was carried out to assess the current gap in modelling functional biomass, starch and TAGs/lipids as a function of light and extracellular nitrogen. It was found that batch and fed batch studies simulated the algae as being composed of only two fractions, lipids and functional biomass. However, the starch fraction was omitted in most published work, although it is a major component of algae and possesses different kinetic behaviour from lipids and functional biomass. Nevertheless, there were some studies of continuous cultures on starch, TAGs and functional biomass, but to date there are no batch mode studies on photosynthetic cultures that model starch, TAGs and functional biomass simultaneously. A mathematical model of starch, TAGs and functional biomass kinetics of C. vulgaris was developed to elucidate the primary mechanisms of photosynthetic kinetics. This was achieved by explicitly modelling starch, TAGs and functional biomass fractions for a batch photosynthetic reactor. In addition, TAGs production due to starch glycolysis was also considered in the model. This biochemical pathway has not been previously modelled in the literature. The model was composed of six coupled ordinary differential equations and 11 secondary equations and was coded and solved in Matlab. The parameters were tuned by minimising an objective function, which was the overall relative error of the model. There were 15-17 biological fitting parameters in the model depending on the limiting conditions affecting starch glycolysis. Four sets of limiting conditions were identified for modelling starch glycolysis and TAGs synthesis from photosynthesis. The first study carried out was the analysis of the influence of extracellular nitrogen on composition kinetics. The nitrogen quota and light dependant photosynthetic activity were found to be primary regulators for starch-TAG kinetics in C. Vulgaris. In contrast metabolite saturation, C-N uptake ratio and starch concentration did not have a significant impact on composition kinetics. Once the influence of nitrogen concentration was investigated, the following step was to test if starch glycolysis was dictating composition kinetics under the influence of moderate to high light intensities. In order to model the influence of carbon uptake for different light fluxes, an exponential decay function, in contrast to the Poisson’s single hit model used in the previous chapter for C. vulgaris, was utilised. The species that was modelled was S. obliquus and the light intensities tested were 200 µmols/m².s and 1000 µmols/m².s. The selection of these conditions was due to the existence of experimental literature values that allowed the validation of the model. The model predicted the experimental data with an average percentage error of 10 % for 200 µmols/m².s and 17 % for 1000 µmols/m².s. The only discrepancy between the model and experiment was for starch concentration for 1000 µmols/m².s light intensity. The origin of this discrepancy was attributed to not accounting for metabolite catabolism of TAGs. This occurred at high light intensities because the culture may have reached a point in its growth phase, where substrate catabolism began. Experimental work was carried out to investigate the composition of S. obliquus for different nitrogen concentration and light conditions. The starch, TAGs, protein and chlorophyll contents were in good agreement with literature values and batch culture model predictions. This agreement between modelling and experiments was arguably attributed to the fact that nitrogen quota, which dictates starch, TAGs and protein kinetics, is independent of reactor running mode, i.e., batch or continuous. Preliminary experiments for mixotrophic algae were conducted at The Port Stephens Fisheries Institute (PSFI) to assess whether mixotrophic cultivation of green algae could improve yields relative to a photosynthetic control. The species that were investigated included N. oculata and T. Chuii. During the first 7 days of growth, cell densities for mixotrophic and phototrophic algae were similar. After this initial period, cell densities of mixotrophic algae were half the density of the photosynthetic culture. Bacterial contamination was the primary reason for a lack of improvement in cell density. It was hypothesised in this thesis that starch glycolysis linked starch degradation to TAGs accumulation during nitrogen depletion. This hypothesis was tested for two different species, C. vulgaris and S. obliquus for different nitrogen and light levels. It was found that starch glycolysis could explain the kinetic behaviour of algae during nitrogen depletion and light intensities in the light limited and saturated region for batch photosynthetic studies. Currently, this has not been reported in literature models. Future studies may attempt to validate this model for species other than green algae or for different growth modes such as heterotrophy or mixotrophy using acetate as a carbon source due to its ability to inhibit bacterial growth.

碩士
國立臺灣海洋大學
水產養殖學系
102
This study isolated Ulva fasciata Delile filaments for algal "seed stock" and mass culture by using those filaments hanging in the land culture tank. The attached seedlings could be repeated harvesting that was the benefit feature of cotton rope hanging cultivation, which could reduce the seedlings and culture time. During the 192 d of cultivation, had harvested total 3880.0 g wet weight and 540.9 g dry weight of the alga. The average growth rate was 3.82 ± 1.61%, and the average biomass was 3.54 ± 0.81 g•m-1day-1. The average growth per 1 g of wet weight alga absorbed 22.42 ± 2.54 g CO₂, the average growth per 1 g of dry weight alga absorbed 157.77 ± 20.59 g CO₂, the average production per unit area was 1743.77 g•m-2 month-1, and the average amount of CO₂ absorption per unit area was 44820 ± 10330 g•m-2 month-1. U. fasciata filaments when cultured under low light 50-100 μmol photons•m-2•s-1, it did not differentiate, but when cultured under light 160-180 μmol photons•m-2•s-1, it grew to form tubular thalli, and then cultured under light 250 μmol photons•m-2•s-1,the tubular thalli transformed into thallus thalli. The filaments could be a "seed stock" of U. fasciata for mass cultivation, and they could also be immobilized by sodium alginate and with PVA embedment technology for long-term storage.

碩士
國立澎湖科技大學
水產資源與養殖研究所
102
As an island county, algal resources are abundant in Penghu islands. However, the majority of algal productivity is based on wild harvesting seaweeds, Monostroma nitidum and Porphyra dentate in the winter. A small scale of aquaculture of P. dentate only occurs in Jiangmei area, but the productivity is remarkably affected by the weather condition . There are nine species of Caulerpa commonly found in Penghu; however, the studies of Caulerpa were focused on taxonomy, not aquaculture. In addition, epiphytic fauna in association with Caulerpa also increase the difficulties of algal farming and reduces the commercial value of Caulerpa. In this study, a market-valued species, C. lentillifera, was selected for aquaculture experiments under different treatments of temperature, salinity, and lighting resource. Methods of epibiotic fauna removal using fresh water, Gram’s Iodine, and acid solution were examined. The optimal culturing temperature for C. lentillifera was ranged in 30 ~ 32 ℃ (0.58 ± 0.21 % day-1). The optimal culturing salinity ranged in 33 ~ 36 psu (0.69 ± 0.52 % day-1). The optimal culturing light intensity ranged in 25 ~ 30 μ mol photon m-2s-1 (1.26 ± 0.16 % day-1). In Penghu, the most commond epiphytic fauna in association with Caulerpa are sea anemone, Aiptasia pulchella, isopod, Tylos minor, and amphipod, Orchestia platensis. The removal rates of A. pulchella, T. minor, and O. platensis on the algae immersed in fresh water for 60 minutes were 46.6 ± 3.2 %, 100 %, and 100 %, respectively. The removal rates of A. pulchella, T. minor, and O. platensis on the algae immersed in 1.5 % Gram’s Iodine solution for 120 minutes were 30.0 ± 10.0 %, 83.3 ± 15.3 %, and 63.3 ± 5.8 %, respectively. The removal rates of A. pulchella, T. minor, and O. platensis on the algae immersed in 10 % vinegar-seawater for 40 minutes were 77.1 ± 21.3 %, 100 %, and 100 %, respectively. The combination of the treatments applied to the algae is likely to maximize removal rate.

Biomass from algae, which is rich in proteins, carbohydrates, and lipids, could be used for the production of biofuels and chemicals. Because algal cultivation and harvesting require high energy and costs, algae-based fuel production is a challenging commercial application. At the pilot scale, this is a common bottleneck problem in algae processing for fuels or chemicals. By implementing an integrated algae biorefinery concept, the need for energy and costs can be reduced. Biopolymers, biochemicals, biofuels, and biofertilizers can all be recovered with higher economic efficiency than conventional methods. A green economy based on algae will also be more viable by reducing production costs. The purpose of this mini-review is to give information about the development of integrated biorefineries for recovery of algal-based bioproducts and their potential applications. The authors discuss the lifecycle assessment and the economic aspects of an integrated algal biorefinery. A discussion of the challenges and future directions of integrated algal biorefinery is concluded.

This study presents designing and managing a green fuel supply chain based on algae to investigate the development of such fuels in the country. On this basis, a definitive model is first developed to model all the activities of the green fuel supply chain, which includes the supply of raw materials for the growth of algae, the cultivation of algae and their conversion into fuel, and finally, the supply of fuel in the country. This deterministic model is extended to a robust network model to secure supply chain decisions against uncertainty. Using the proposed model for the development of algal fuels in Iran shows that the green fuel production cost is currently 27 cents/liter. The current cost of producing fuel from algae cannot compete with fossil fuels, but this cost can be greatly reduced in the future by slightly increasing the growth rate of algae and their oil content.

The promise of algae to address the renewable energy and green-product production demands of the globe has yet to be realized. Over the past ten years, however, there has been a substantial investment and interest in realizing the potential of algae to meet these needs. Tremendous progress has been achieved. Ten years ago, the price of gasoline produced from algal biomass was 20-fold greater than it is today. Technoeconomic models indicate that algal biocrude produced in an optimized cultivation, harvesting, and biomass conversion facility can achieve economic parity with petroleum while reducing carbon-energy indices substantially relative to petroleum-based fuels. There is also an emerging recognition that algal carbon capture and sequestration as lipids may offer a viable alternative to direct atmospheric CO2 capture and sequestration. We review recent advances in basic and applied algal biomass production from the perspectives of algal biology, cultivation, harvesting, energy conversion, and sustainability. The prognosis is encouraging but will require substantial integration and field testing of a variety of technology platforms to down select the most economical and sustainable systems to address the needs of the circular economy and atmospheric carbon mitigation.

Recently, algae have received considerable interest as one of the most promising feedstocks suitable for animal feed production due to their fast growth, less nutrient requirements and their ability to produce primary and secondary metabolites with high-added value. Different strategies were applied to improve both biomass and metabolites productivities aiming to produce highquality biomass with low cost and high nutritional value. Tetraselmis subcoliformis QUCCCM50, a local marine green alga presenting fast growth, high metabolites content and easy to harvest, was selected as a candidate for feed production. Three different stress conditions were applied to enhance its potential to produce high-value products such as Nitrogen or Phosphorus depletion and high salinity of 100ppt. An assessment of the growth properties and biomass productivity was performed during the growth. After 15 days of cultivation using tubular photobioreactors, the biomass was subjected to metabolites characterization and fatty acids methyl ester profiling. Results showed that the three stress conditions present different impacts on biomass productivity and, lipid quantity and quality. Cultivation under 100 ppt led to the highest increase in lipid content. This culture condition led to 25% increase of the omega-3 fatty acids with the appearance of the docosahexaenoic acid (DHA) and a remarkable increase of the alpha-linolenic acid, comparatively to the control. The enrichment of the Tetraselmis subcoliformis’ biomass in terms of omega-3 fatty acids enhance its nutritional value and make it very suitable for animal feed production. The optimized culture conditions obtained from the current study will be applied at large scale to enhance the quality of the biomass towards omega-3 enriched animal feed supplement production, and hence support achieving food security in the State of Qatar.

A numerical study is presented aiming to maximize the solar to hydrogen energy conversion efficiency of a symbiotic culture containing microorganisms with different absorption characteristics. The green algae Chlamydomonas reinhardtii CC125 and the purple non-sulfur bacteria Rhodobacter sphearoides ATCC 49419 are chosen for illustration purposes. The previously measured radiation characteristics of each microorganism are used as input parameters in the radiative transport equation for calculating the local spectral incident radiation within a flat panel photobioreactor. The specific hydrogen production rate for each microorganism as a function of the available incident radiation is recovered from data reported in the literature. The overall solar to hydrogen energy conversion efficiency of symbiotic cultures of varying microorganism concentrations have been computed for photobioreactor thicknesses from 1 to 10 cm. The results show that for a given photobioreactor thickness a saturation microorganism concentration exists above which the solar energy conversion efficiency does not increase. The maximum solar energy conversion efficiencies of solo cultures of C. reinhardtii and R. spaheroides at their respective saturation concentrations are 0.06 and 0.055%, respectively. Using symbiotic cultures, a total conversion efficiency of about 0.075% is achieved within the parameter range explored. It has been shown that the choice of microorganism concentrations for maximum solar energy conversion efficiency is non-trivial and requires careful radiation transfer analysis coupled with H2 production kinetics taking into account the photobioreactor thickness. The presented numerical tool can be used for simulating any photobiological or photochemical process involving more than one species with different radiation characteristics provided the closure laws for the reaction kinetics are known as a function of spectral incident radiation. Examples include (i) the symbiotic cultivation of more than one microorganism for biomass or lipid production in a photobioreactor and (ii) a photochemical reactor containing a number of absorbing and scattering photocatalysts with different band gaps.