Micro-algae harvesting is the second step in the bio-energy production
chain. Due to the size of micro-algae and the low concentration
of algae in growth medium during cultivation, the energy
consumption is substantial [19,44,46]. A number of harvesting
and dewatering options are described by [44], most of which are
too expensive or hardly applicable for large-scale bio-energy purposes.
Harvesting options should be able to process large flows, enable
recycling of separated water, energy extensive, have a low
residence time and low costs. The micro-algae growth model is
used to determine the harvesting capacity desired per location
and cultivation system. The capacity is based on the maximum
8 h average productivity and the micro-algae concentration in slurry
before harvesting. Pre-harvesting algae concentration is 0.4 g/l
and 2 g/l for raceway ponds and horizontal tubular systems.
Three main harvesting methods were selected as harvesting options:
settling ponds, centrifuge, AVS harvesting and combinations
of those methods. Settling ponds are unmixed ponds. Algae biomass
is concentrated by gravity sedimentation, and surplus water