A case study on the treatment and recycling of the effluent generated from a thermo-mechanical pulp mill in Brazil after the installation of a new bleaching process

Daiane Cristina Diniz Caldeira; Cláudio Mudadu Silva; Jorge Luiz Colodette; Fábio de Ávila Rodrigues; Rafles Anselmo Da Mata; Karyna da Silva Menezes; Jhennifer Cristina Vieira; Antonio José Vinha Zanuncio

doi:10.1016/j.scitotenv.2020.142996

A case study on the treatment and recycling of the effluent generated from a thermo-mechanical pulp mill in Brazil after the installation of a new bleaching process

Sci Total Environ. 2021 Apr 1:763:142996. doi: 10.1016/j.scitotenv.2020.142996. Epub 2020 Oct 15.

Authors

Daiane Cristina Diniz Caldeira¹, Cláudio Mudadu Silva², Jorge Luiz Colodette³, Fábio de Ávila Rodrigues⁴, Rafles Anselmo Da Mata⁵, Karyna da Silva Menezes⁶, Jhennifer Cristina Vieira⁶, Antonio José Vinha Zanuncio⁷

Affiliations

¹ Department of Civil Engineering, Universidade Federal de Viçosa, 36,570-900 Viçosa, Minas Gerais, Brazil. Electronic address: daianediniz7l@gmail.com.
² Department of Forest Engineering, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil. Electronic address: mudado@ufv.br.
³ Department of Forest Engineering, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil.
⁴ Department of Chemical Engineering, Universidade Federal de Viçosa, 36,570-900 Viçosa, Minas Gerais, Brazil.
⁵ Department of Civil Engineering, Universidade Federal de Viçosa, 36,570-900 Viçosa, Minas Gerais, Brazil.
⁶ Department of Environmental Engineering, Universidade Federal de Viçosa, 36,570-900 Viçosa, Minas Gerais, Brazil.
⁷ Institute of Agricultural Sciences, Universidade Federal de Uberlândia, 38500-000, Minas Gerais, Brazil.

PMID: 33498121
DOI: 10.1016/j.scitotenv.2020.142996

Abstract

A Brazilian thermo-mechanical pulp mill (TMP) was evaluating the installation of a proposed bleaching process, with changes in the qualitative and quantitative characteristics of the wastewaters and the Effluent Treatment Plant (ETP). The objectives of this research were to evaluate the treatment plant configuration for the future industrial effluent, consisting of a flotation unit followed by an upflow anaerobic sludge blanket reactor (UASB), an activated sludge process and nanofiltration (NF) using polymeric membranes, and to study the technical feasibility of recycling the treated effluents in the industrial process. The possible options for recycling the treated effluent were determined through a water balance of the mill. The pulp quality was evaluated in laboratory bleaching assays, based on brightness and brightness reversion tests after the recycling of 50%, 75% and 100% of the treated effluent. The buildup of the non-process elements (NPE) in the industrial water cycle after each effluent recycling proportion was evaluated through computer simulation, using the Aspen Plus® simulator software. The future mill effluent, considering the implementation of a proposed bleaching stage with hydrogen peroxide, was generated in the laboratory and treated in a bench-scale effluent plant, simulating the future configuration. The treatment plant removed 99.8%, 99.2% and 61.6% of soluble COD, BOD₅ and color, respectively. The water consumption was highest in the bleaching plant and, therefore, the recycling of 50%, 75% and 100% of the treated effluent for washing the pulp was simulated. The brightness and brightness reversion of the pulp, with 100% of the treated effluent used in the bleaching process, were similar to those provided by fresh water. The recycling of 100% of the treated effluent in the proposed treatment plant was possible in the TMP pulp mill without decreasing the pulp quality.

Keywords: Closing the water circuit; Computational simulation; Pulp bleaching; Thermo-mechanical pulp mill; Wastewater recycling; Zero effluent.