Fractionation of polyphenols from thermomechanical pulp mill process water by flotation and membrane integrated process

Abstract

Fractionation of phenolic compounds in thermomechanical pulp mills was performed with a coupling of a prior treatment realized by flotation and a ceramic membrane process. Two lines of membranes filtration were tested. After a common 150 kDa clarification, 1 kDa filtration was performed with or without previous 5 kDa filtration. Flotation was shown to be inevitable to retain lipophilic compounds which cause severe membrane fouling. 150 kDa permeate flux was 20% higher when process water was firstly floated and was around 260 L h m. 1 kDa membrane was fouled with 31% of irreversible fouling without previous 5 kDa filtration and phenolic compounds purity reached only 26% in this 1 kDa permeate. Phenolic compounds as lignin-like substances which might be attached to hemicelluloses were recovered in 5 kDa retentate. Retentate of 1 kDa might contain a major fraction of lignin derivatives with molecular weights around 1 kDa free or linked with phenolic acids. Permeate of 1 kDa contained 14% of phenolic compounds such as lignans and free phenolic acids purified at 50%.

Recovery of lignin and lignans enriched fractions from thermomechanical pulp mill process water through membrane separation technology: Pilot-plant study and techno-economic assessment

“…This latter advantage leads to end products of high quality, and makes it easier to comply with the many stringent requirements from both consumers and public authorities (Steinmetz et al, 2019). Many studies report the use of membrane technology for TMP waters fractionation for galactoglucomannans (GGM) valorisation as biopolymer for example (Persson and Jönsson, 2010a;Thuvander and Jönsson, 2016) whereas only two studies had the objective of lignin and extractives valorisation (Persson et al, 2010b;Courbalay et al, 2018b). They are usually performed with discontinuous mode (i.e.…”