Effect of draw solution type and operational mode of forward osmosis with laboratory-scale membranes and a spiral wound membrane module

“Forward osmosis (FO) is a concentration driven membrane process which recently gained an
increase in attention due to the development of improved FO membranes. Most of the currently
available data on FO research is obtained on small laboratory-scale set-ups, thereby overlooking the
effects of scaling-up to pilot or full-scale size. In this paper, FO experiments are carried out with a
10.16 cm (4-in) spiral wound FO (SWFO) Hydration Technologies Innovations (HTI) module. The
performance of the SWFO module was investigated during daily experiments and the influence of
two types of draw solutions (NaCl and MgCl2) was evaluated and compared to data from lab-scale FO
research. Furthermore, the difference between fixed draw solution concentration and draw solution
dilution was studied for both draw solutions. Salt flux was determined from the increase in:
(i) conductivity; and (ii) individual ion concentration in the feed vessel. Water and salt flux values from
laboratory-scale membrane FO experiments were similar but slightly lower than that of the SWFO
module in the fixed draw solution concentration experiments (respectively 5 L/m2h and 3 g/m2h for
0.5 M NaCl). Salt flux values obtained from individual ion measurements were lower and more
accurate compared to that determined by conductivity measurements.”

(Citaat: Cornelissen, E.R., Harmsen, D.J.H., etal. – Effect of draw solution type and operational mode of forward osmosis with laboratory-scale membranes and a spiral wound membrane module – Journal of Water Reuse and Desalination 1(2011)3, p.133-140 – Open Access)