Minimization of Environmental Impact of Kraft Pulp Mill Effluents: Current Practices and Future Perspectives towards Sustainability

Gladys Vidal,Yenifer González,Mayra Jarpa,Gloria Gómez,Benjamín Piña

doi:10.3390/su13169288

Abstract

Kraft mill effluents are characterized by their content of suspended solids, organic matter and color due to the presence of lignin, lignin derivatives and tannins. Additionally, Kraft mill effluents contain adsorbable organic halogens and wood extractive compounds (resin acids, fatty acids, phytosterol) and show high conductivity due to the chemical compounds used in the digestion process of pulp. Currently, Kraft mills are operating under the concept of a linear economy and, therefore, their effluents are generating serious toxicity effects, detected in daphnia, fish and biosensors. These effluents are treated by activated sludge and moving bed biofilm systems that are unable to remove recalcitrant organic matter, color and biological activity (toxicity) from effluents. Moreover, under climate change, these environmental effects are being exacerbated and some mills have had to stop their operation when the flows of aquatic ecosystems are lower. The aim of this review is to discuss the treatment of Kraft pulp mill effluents and their impact regarding the current practices and future perspectives towards sustainability under climate change. Kraft pulp mill sustainability involves the closure of water circuits in order to recirculate water and reduce the environmental impact, as well as the implementation of advanced technology for these purposes.

Highlights

Latin America is leading the installed capacity of Kraft pulp mills, surpassing the installed capacity in North America
Potential biological effects of Kraft mill effluents have been studied in experimental exposure experiments in fish [29,31] or Daphnia magna [6,32,33]
In this case, the research group has detected estrogenic activity of Kraft mill treated effluent by a recombinant Saccharomyces cerevisiae yeast

Summary

Introduction

Latin America is leading the installed capacity of Kraft pulp mills, surpassing the installed capacity in North America. The developing countries that install this type of Kraft pulp mill generate processes with the best available technology (BAT) in the market, that is, with continuous pulp digestion systems and elemental chlorine-free (ECF) bleaching pulp. Developed countries face growing conservationist pressures that limit or make it more difficult to obtain raw materials for industry. In these countries, there are still very competitive locations for the development of plantations; the requirements for forest management certifications and sustainability codes are universal for all countries that produce and export pulp. Europe is no longer the most important regional market, being displaced by China, and pulp based on eucalyptus continues to lead the market growth, adding 3.1 million tons of annual growth

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Results

Conclusion