Desalination by pulsed electrodialysis reversal: Approaching fully closed-loop water systems in wood pulp mills

Alvaro Gonzalez-Vogel,Juan J Moltedo,Orlando J Rojas

doi:10.1016/j.jenvman.2021.113518

Alvaro Gonzalez-Vogel, Juan J Moltedo + Show 1 more

Open Access

https://doi.org/10.1016/j.jenvman.2021.113518

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Abstract

A pulsed electrodialysis reversal (pEDR) process is proposed to desalinate spent water after particle removal, biological and chemical coagulation, which are commonly used as a sequence in Kraft pulp mills. pEDR affords closed-loop processing, reducing the need for freshwater intake while maintaining the quality of recirculating process streams. Compared with conventional electrodialysis, pEDR minimizes production losses (from 5 % to 0.6 %), extending the time for hydraulic reversal (from 15 min to at least 2 h). Simultaneously, the conductivity of the effluent is significantly reduced, from 2100 to 200 μS/cm, reaching a quality similar to the feed water. The operation cost (0.38 US$/m3) is factored in the techno-economic viability of the process water recirculation, which is also demonstrated for its scalability. Additionally, WinGEMS simulation highlights the benefits of installing a pEDR unit, positively impacting mill water under different recirculation rates. Overall, we show remarkable gains in water economy, operation (maintenance and fouling), and quality, which are critical factors in achieving resource sufficiency.

Highlights

Water is a key resource for life and human activities, including those associated to processing and manufacturing
Given that Kraft pulping effluents are rich in organic matter and recalcitrant material, we considered ED as a more suitable alternative to reverse osmosis (RO) for desalination
Conclusions pulsed electrodialysis reversal (pEDR) is identified as a suitable technology for the desalination of wastewater in a Kraft pulp mill

Summary

Introduction

Water is a key resource for life and human activities, including those associated to processing and manufacturing. Concerns about pollution and scarcity are continuously increasing, especially considering the added effects of climate change. As most industries, those in the forest products sector require large volumes of water; ensuring the viability of such natural resource and limiting any environmental impact is a mandate. Those in the forest products sector require large volumes of water; ensuring the viability of such natural resource and limiting any environmental impact is a mandate Such factors highlight the important consideration of closed-loop systems for industrial operations (Gavrilescu and Puitel, 2007). Recirculation is restricted by the accumulation of organics and non-process elements (NPEs) such as K, Si, Ca, Ba, Fe, Cu, Mn, Al, Cl, among others (de Almeida Batista et al, 2020). Non-process elements promote corrosion and scaling of processing units, including boilers and piping systems

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