Evaluation of Nanofiltration for the Recovery of Brine from Sugar Liquor Decolourising Resin Regeneration Waste

Abstract

The recovery of brine from the regeneration effluent from cane sugar Liquor decolourising ion exchange resin by means of nano filtration has been investigated on a Laboratory and pilot plant scale. This effluent is produced at 80°C and contains up to 110 g/ℓ of sodium chloride and up to 6 g/ℓ (as total carbon) of organic matter. The SelRO MPT-30 membrane was selected for the pilot plant trials, which were carried out at 3 MPa and 45 °C or 60 °C. Point retention values ranged from (-2) to 15 % for sodium chloride and from 71 to 93 % for total carbon. Final water recoveries between 69 and 83 % were investigated. The sodium chloride recovery ranged from 64 to 81 % and the total carbon removal ranged from 79 to 89 %. Based on experiments using the salt-rich fraction of the effluent and a water balance over the regeneration system, it was calculated that a 30 % reduction in effluent volume and a 60 % reduction in salt consumption could be achieved. In the tests carried out so far, the use of the recovered brine in the regeneration of pilot resin columns did not lower the decolourising capacity of the resin.