Biohydrogen production by Rhodobacter capsulatus Hup− mutant in pilot solar tubular photobioreactor

Passive temperature control of an outdoor photobioreactor by phase change materials

“…The PCM needs to change phase twice during a day; once during the day to absorb the heat, the other during the night to release the stored heat. Typical temperature range of a summer day is 20 to 35°C, and temperature of an uncontrolled photobioreactor is expected to change by between 20 and more than 45°C based on previous publications . A PCM with a melting point of 30–35°C would be ideal for this case.…”

“…Typical temperature range of a summer day is 20 to 35 ∘ C, and temperature of an uncontrolled photobioreactor is expected to change by between 20 and more than 45 ∘ C based on previous publications. 3,4,6,9,10 A PCM with a melting point of 30-35 ∘ C would be ideal for this case. Based on these considerations, both an organic and an inorganic PCM were selected as candidate PCMs to be used in this study.…”

“…For instance, the highest temperaturesat which Rhodobacter species, which are mesophilic purple non‐sulfur bacteria, can grow are reported to be 39°C for wild type R. capsulatus and R. sphaeroides , 42°C for temperature‐resistant mutants of R. Capsulatus , and 45°C for R. centenum which is the most heat tolerant species known . However, it has already been reported that in a solar photobioreactor which lacks temperature control, the temperature increases to lethal levels (45–60°C) during daytime due to the absorbed sunlight by photosynthetic bacteria, thus cooling methods (such as water spraying, external or self shading, circulating chilled water in cooling coils, using a process water cooler) are needed to be adapted to the system . Similarly, the control of temperature is a major problem encountered in photobioreactor systems containing microalgae.…”

“…Rhodobacter species) are reaching pilot scale testing. 3,4 Although lab scale photobioreactors may be illuminated artificially by lamps simulating sunlight, large scale industrial photobioreactors need to be operated under natural sunlight due to economic constraints. Solar photobioreactors can be categorized as either open (i.e.…”

“…7 However, it has already been reported that in a solar photobioreactor which lacks temperature control, the temperature increases to lethal levels (45-60 ∘ C) during daytime due to the absorbed sunlight by photosynthetic bacteria, thus cooling methods (such as water spraying, external or self shading, circulating chilled water in cooling coils, using a process water cooler) are needed to be adapted to the system. 3,4,6,9,10 Similarly, the control of temperature is a major problem encountered in photobioreactor systems containing microalgae. They may generate considerable amounts of heat, which may cause temperature changes of 20 ∘ C within a single day if (costly) temperature control systems are not provided.…”