Bioremediation approaches for treatment of pulp and paper industry wastewater: Recent advances and challenges

Abstract

Pulp and papermaking industry is a large consumer of fresh water and also an important source of dark-brown-colored wastewater, generated during various stages of pulping and papermaking activities. The colored wastewater discharged from pulp and paper industry even after secondary treatment remains toxic and complex in nature and retains high amount of lignin, lignin residues, resins, acids, chlorinated phenols, and various persistent organic pollutants (POPs) including the adsorbable organic halides (AOXs; halogenated or organochlorine). The existing various conventional methods along with integrated processes (aerated lagoons and activated sludge plants) cannot efficiently treat pulp and paper industry wastewater due to its complex and recalcitrant nature. Hence, the discharged partially treated/or untreated wastewater are contributing to deteriorating water quality due to increasing biological oxygen deman and chemical oxygen demand and decrease of dissolved oxygen. In a terrestrial ecosystem, the wastewater irrigated soil showed decrease of moisture content and increase of pH and toxic heavy metals content. To tackle this problem associated with hazardous waste disposal, the existing pulp and paper industry wastewater treatment process needs to be improved with better treatment outcomes. Although, several physicochemical methods are available for the treatment of such wastewater, they are more energy intensive and suffer from residual effect. In addition, they are very expensive, inefficient, and produce a huge amount of toxic sludge which is difficult to handle and also produces volatile organic compounds on burning. To combat these challenges, biological treatment using bacteria, fungi, yeasts, and algae has evolved as a preferred means to treat and reduce the toxic organic compounds loaded in generated pulp and paper industry wastewater.