No abstract

Photosynthetic activity and temperature regulation of microalgal cultures (Chlorella vulgaris and Scenedesmus obliquus) under different irradiances controlled by a solar tracker and different cell densities were studied in outdoor flat panel photobioreactors. An automated process control unit regulated light and temperature as well as pH value and nutrient concentration in the culture medium. CO2 was supplied using flue gas from an attached combined block heat and power station. Photosynthetic activity was determined by pulse amplitude modulation fluorometry. Compared to the horizontal irradiance of 55 mol photons m(-2) d(-1) on a clear day, the solar tracked photobioreactors enabled a decrease and increase in the overall light absorption from 19 mol photons m(-2) d(-1) (by rotation out of direct irradiance) to 79 mol photons m(-2) d(-1) (following the position of the sun). At biomass concentrations below 1.1 g cell dry weight (CDW) L(-1), photoinhibition of about 35 % occurred at irradiances of ≥1,000 μmol photons m(-2) s(-1) photosynthetic active radiation (PAR). Using solar tracked photobioreactors, photoinhibition can be reduced and at optimum biomass concentration (≥2.3 g CDW L(-1)), the culture was irradiated up to 2,000 μmol photons m(-2) s(-1) to overcome light limitation with biomass yields of 0.7 g CDW mol photons(-1) and high photosynthetic activities indicated by an effective quantum yield of 0.68 and a maximum quantum yield of 0.80 (F v/F m). Overheating due to high irradiance was avoided by turning the PBR out of the sun or using a cooling system, which maintained the temperature close to the species-specific temperature optima.

No abstract

No abstract

A membrane unit in pilot scale is operated to provide a CO2‐enriched product stream from flue gas of a natural‐gas‐fuelled heating system. The CO2 stream is fed to a cultivation medium of photobioreactors that are integrated in the façade of the building project ‘BIQ – The Algae House’ (International Building Exhibition 2013/Hamburg), where CO2 is required as the carbon source for the growth of algae, which are cultivated in the bioreactors. This work presents a long‐term field test. Furthermore, a possibility for the usage of CO2 separated de‐centrally is given. The operational conditions for the membrane module cause additional mechanical stress on the membrane material since the pilot plant is operated with periodic start‐ups and shut‐downs. The occurrence of acidic water on the membrane generates additional potential damage of the material. The field test is planned to be carried out for several years to prove the reliability of this membrane technology in flue gas treatment. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd