Microbial biotechnology as an emerging industrial wastewater treatment process for arsenic mitigation: A critical review

Industrial wastewater pollution has become more grievous in the third world countries, where treatment and administration of industrial effluents are not being properly handled. About 80% of wastewater having arsenic (As) contamination are due to impurities in pesticides, chromated copper arsenate (CCA) wood preservatives, municipal solid waste incineration; leather industry; and consumption in the industry. Arsenic is a toxic metalloid, which is considered as a severe menace to the life of plants, animals and humans. Some As species such as As(III) and As(V) cause harmful effects on plants and animals. In order to treat As in industrial wastewater, various conventional methods are being employed. However, these methods face limitations in form of missing technical expertise and low effectiveness. Recently, microbial As remediation of industrial water has been evolved as a promising technology due to its public acceptance and cost effectiveness. The current review, for the first time, comprehensively summarizes the role of microbial remediation of As in industrial wastewater. In contrast to phytoremediation, the goal of using microbes is that dissolved arsenic species are converted microbially to arsine gas which is released into the atmosphere at non-toxic levels (dilution effect). In contrast to phytoremediation where arsenic is accumulated in plant material (waste production), this will not produce any solid or liquid waste - and this is just a key benefit of the microbial approach as the management of solid/liquid arsenic rich waste is a global concern and economic burden; however, it was so far only tested on laboratory scale with exception of biofilms that have been tested on pilot scale. Our review also indicated the huge undervalued potential and environmental friendly solution of microbial remediation of As contaminated industrial wastewater without solid/liquid waste production as conventional technologies do.