The textile industry produces large volumes of wastewater that requires appropriate treatment before being released into the environment. Research globally has focused on advanced desalination technologies to augment the limited freshwater resources. Forward osmosis (FO) technology has gained substantial interest as a possible lower-energy desalination technology. However, challenges such as the availability of effective draw solutions (DS) have limited its implementation. This study evaluated alternative feed water resources and assessed the potential of dye solutions as DS. The aim is to dilute a concentrated dye DS to a target concentration for direct dye-batch use, thereby reclaiming water resources. The measured osmotic pressure (OP) of the alternative feed solutions (synthetic brackish water; syntethic seawater; seawater from the Atlantic and Indian Oceans; and wastewater from two textile factories) were 414, 2 761, 2 580, 2 614; 1 716 and 7 822 kPa, respectively. Three basic dyes (Maxilon Turquoise, Red and Blue) and three reactive dyes (Carmine, Olive Green and Black) were selected based on common use in the South African textile industry. The dye samples were prepared without and with salt at different concentrations and different dye-to-salt mass ratios ranging from 1:10 to 1:60. The OP trends for the basic dyes followed Blue >> Red > Turquoise and for the reactive dyes Black >> Olive > Carmine. The overall OP trend was Black > Olive > Carmine > Blue > Red > Turquoise. The OP at different dye concentrations and different dye-to-salt ratios was mostly influenced by the dye chemistry and molecular weight (Mw) rather than the type of dye, i.e., reactive vs basic.The OP trend for the dye-to-salt ratios was 1:60 > 1:50 > 1:40 > 1:30 > 1:20 > 1:10. For both the basic and reactive dyes a linear relationship exists between OP and dye concentration; as well as between OP and Mw. The dye DS exhibited larger OP compared to that of the FS evaluated, thus rendering them suitable DS.

The production of extracellular enzymes is gaining momentum as commercial interests seek alternative ways to improve the productivity in the biotechnology and pharmaceutical industries. Early research studies looked at improving batch bioreactor operational challenges; however, the use of continuous cultures was indicated to be favourable. This led to a new approach developed to produce extracellular enzymes continuously using fixed-film bioreactors from biofilms immobilised on polymeric and inorganic membranes. In this review, the performance of P. chrysosporium biomass, evaluated in terms of ligninase production using different bioreactor operation conditions, is highlighted. Furthermore, the limitations related to the implementation of optimised batch culture conditions to continuous fixed-film bioreactors are discussed. DO transportation, trace element toxicity and lipid peroxidation effects on P. chrysosporium biomass in fixed-film bioreactors operated for elongated periods, are also discussed.