During the processing of whey for the production of WPC, high
volumes of a lactose-rich stream, the permeate, are also obtained. The
permeate remains a major pollutant since it retains the lactose, which
represents more than 70% of total whey solids and is largely responsible
for the whey polluting load. Therefore, the permeate creates disposal
problems, in terms of volumes produced and polluting load, almost
equal to the disposal of raw whey (Zall, 1984).