used to increase the dry material from 56% up to
30-40%. The addition ofproteolytic enzymes to the
stickwater enables the solids content to increase
up to approximately 50% [6]. Reverse osmosis is
a suitable technique for the pre-concentration of
the solids from 56% up to approximately 20%
[7-81. By enzyme treatment the preliminary
removal of water by RO may also eventually be
improved. Billiet and Fenyo [9] investigated the
separation of proteins and salts from fish-press
waste generated in the fish meal manufacturing
process, which contains high levels of organic
matter (BOD, = 75 g 0,/l, COD = 130 g 0,/l).
Anaerobic treatment was inefficient due to the
high salt contents (50-130 g/l), whereas UF with
Millipore cartridges (10 kDa) proved to be efficient.