High frequency pulsed electrodialysis of acidic filtrate in kraft pulping

We introduce high frequency pulsed electrodialysis (hf-pED) to process the acidic filtrate of a Kraft pulp bleaching stage, tested in a pilot trial. Compared with conventional electmdialysis, hf-pED at 2,000 Hz allows a reduction in operational cost by 12%, estimated as 0.54 USD/m(3) of acidic filtrate, while simultaneously preventing membrane fouling. The proposed sectorial stream treatment is demonstrated to significantly improve the quality of the final effluent, according to mass balances, making it more suitable for irrigation applications, considering requirements of irrigation norms. Thus, we estimate a reduction of 59, 21, and 20% in the concentration of chloride, sodium, and sulfate, respectively, in the final effluent of a conventional Kraft pulping mill. This strategy is presented as a sustainable and economic solution compared with the desalinization of the whole final effluent.

Automated summary

The high frequency pulsed electrodialysis (hf-pED) technology reduces operational costs and prevents membrane fouling when processing the acidic filtrate of a Kraft pulp bleaching stage, leading to a significant improvement in the quality of the final effluent for irrigation applications. This sustainable and economic solution also results in a reduction in chloride, sodium, and sulfate concentrations in the final effluent compared to conventional desalination methods.