The scale up for indoors and outdoors pilot photo-bioreactor algal production is critical step. Transferring lab results to large scale condition will require optimization and testing. For the successful growth of algae cultures, the bioreactor must be adapted to attend as many of the species requirements as possible. Environmental factors like temperature, light intensity, nutrient cycling, water chemical composition, nutritional requirements, among others, are key to the success of commercial application.
The challenge is to scale up the algal culture in a controlled environment as light requirements constrain the design options. Moreover, there is a need to increase both volume and surface area when scaling up. Importantly, the cost of the reactor, as the capital investment has to be minimized.
The primary considerations for large scale production of algae, include:
a) Cost of equipment and infrastructure,
b) Light intensity and cycling,
c) Temperature tolerance and variation,
d) Total salt concentration, carbon and nitrogen economic sources, as well as concentrations of the other major elements such as magnesium, potassium, sulfate, sodium, and phosphate in the media,
e) Trace solutions (manganese, nickel, zinc, boron, vanadium, cobalt, copper and molybdenum) present in the media,
f) Need of adding organic components and growth promoting substances like vitamins and hormones.
We have experimented with tubular photoreactors with tubes made of clear PVC. This is a very useful material, but markedly expensive. Currently, we are working in a better option, vertical flexible plastic bags that are showing very promising results. We have these reactors in use in outdoors conditions without any environmental control, and in an indoors controlled environment.