Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD) and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively.

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Membrane reactors offer a promising configuration for enzymatic delignification processes (lignin modification, removal and utilization). However, membrane fouling reduces the efficiency of filtration and of the entire bioprocess. The flux and retention characteristics of protein-ligninsulfonate model mixtures were investigated. A 5-kDa tubular ceramic membrane achieved a sufficient and constant ligninsulphonate retention of 80â90%. The retention of phenolic monomers (e.g. guaiacol) increased with the ligninsulphonate concentration. Mass transfer-controlled regions were observed in which permeate fluxes could be predicted by the limiting flux model. Finally, the underlying fouling mechanisms were evaluated, revealing a predominance of complete pore blocking and cake filtration

Photocatalysis, belonging to the advanced oxidation processes (AOPs), is a potential new transformation technology for lignin derivatives to value added products (e.g., phenol, benzene, toluene, and xylene). Moreover, lignin represents the only viable source to produce aromatic compounds as fossil fuel alternative. This review covers recent advancement made in the photochemical transformation of industrial lignins. It starts with the photochemical reaction principle followed by results obtained by varying process parameters. In this context, influences of photocatalysts, metal ions, additives, lignin concentration, and illumination intensity and the influence of pH are presented and discussed. Furthermore, an overview is given on several used process analytical methods describing the results obtained from the degradation of lignin derivatives. Finally, a promising concept by coupling photocatalysis with a consecutive biocatalytic process was briefly reviewed.

Enzyme membrane reactor systems (EMRS) offer a promising configuration for an enzymatic lignin modification/valorization by newly versatile peroxidases. This work continues in the same direction as our previous investigations using a 5-kDa tubular ceramic membrane for the fractionation of protein-ligninsulfonate model mixtures. Based on these preliminary studies, an in silico investigation is carried out for approximating the maximum product yield of an EMRS per operation cycle and membrane area. As a result, a permeate flux of 4 L mâ2 hâ1 was optimal for the 5-kDa membrane. In this context, a first assessment is given regarding fluid flow-related losses in versatile peroxidase activity