Worldwide, there are many existing biological and chemical treatment processes for paper and
board mill effluent such as those based on aerobic, anaerobic, algal, fungal biomass, ozonation,
electrochemical, photocatalytsis, coagulation-flocculation treatment, etc. [12-19]. In general, the main
treatment process used at pulp and paper mills plants is primary clarification, succeeded in some cases
by secondary treatment, generally of a biological nature (anaerobic treatment, aerated lagoons and
activated sludge) [20]. These classical treatments have been successful in lowering the chemical and
biological oxygen demands (COD, BOD, respectively), but their applicability is limited by a great
number of problems. These biologically treated effluents still contain significant amounts of coloured
compounds, microorganisms, recalcitrant organics and a minor amount of biodegradable organics, as
well as suspended solids. Biological treatment does not significantly reduce the inorganic content in
the effluent and desalting is sometimes needed before reuse of the effluents in the manufacturing
processes [21]. Given the limitations of the current biological wastewater treatment, there is an
increasing interest to develop a more effective treatment approach to reduce the impacts of pulp mill
effluents on the environment.