Process-integrated, continuous, separation of lignin from kraft pulp mills which results in a ligninwith low ash content (0.05-1 %) is relatively new technology compared to traditional kraft pulping subprocesses,like recovery boilers, lime kilns, white liquor preparation etc. The LignoBoost technology wasdemonstrated in 2007 and the first commercial full-scale process started in 2013, delivered to Domtarby Valmet. This means that this concept now has been in commercial scale operation for almost 10years. There is also an alternative commercialized concept available today from another supplier,NORAM International. The idea to integrate lignin separation into a kraft pulp mill is today quite provencommercial technology.This paper will discuss different learnings, experiences, from the early development of theLignoBoost process, which includes handling of the separated lignin followed by drying. The dustexplosion risk is relatively high for dry kraft lignin due to a high kst value – so the paper will also discussif there are opportunities to reduce this risk. The paper will also briefly discuss promising productsegments for kraft lignin.

The market for kraft lignin is growing. Existing markets for lignin-based products are growing andseveral new applications are close to commercialization. To enable this growth and facilitate the newlignin-based products under development, it is important to understand the requirements in differentapplications and which lignin properties can be changed. It is thus important to use the type of ligninsuitable for the targeted end application.

Lignin´s properties are dependent on raw material and process for separation. Several parameterslike purity, oxygen content, and content of volatiles can be tuned. Different end- products have verydifferent demands on the feedstock for the process. One lignin quality is therefore not sufficient tounlock the vast potential that lignin has in the transition to a more sustainable society with morebiobased materials.

LignoCity offers knowledge, experience, and a flexible process for the production of tailormadelignin qualities. With the knowledge of the demand on the feedstock for different applications, we cansupport different stakeholders in the development of various lignin value chains.

Kraft lignin is an underutilized resource from the pulp and paper industry with the potential of being a key raw material for renewable fuels and chemicals. The separation of high-molecular-weight lignin from black liquor by ultrafiltration has been widely investigated, while the permeate containing low-molecular-weight lignin has received little attention. Nanofiltration can concentrate the low-molecular-weight lignin. This work, therefore, evaluates nanofiltration for the separation and concentration of low-molecular-weight lignin from the ultrafiltration permeate. For this study, eight flat polymeric sheet membranes and one polymeric hollow fiber membrane, with molecular weight cut-offs ranging from 100 to 2000 Da, were tested. A parametric study was conducted at 50 °C, 2.5–35 bar, and crossflow velocity of 0.3–0.5 m/s. At a transmembrane pressure of 35 bar, the best performing membranes were NF090801, with 90% lignin retention and 37 L/m2·h, and SelRO MPF-36, with 84% lignin retention and 72 L/m2·h. The other membranes showed either very high lignin retention with a very low flux or a high flux with retention lower than 80%. Concentration studies were performed with the two selected membranes at conditions (A) 50 °C and 35 bar and (B) 70 °C and 15 bar. The NF090801 membrane had the highest flux and lignin retention during the concentration studies. Overall, it was shown that the nanofiltration process is able to produce a concentrated lignin fraction, which can be either used to produce valuable chemicals or used to make lignin oil.

Kraft lignin is an aromatic polymer found in black liquor, a side stream of the kraft pulping industry.Usually, lignin is burned in the recovery boiler of the pulp mill as a fuel for energy generation. However,lignin has great potential as a raw material for the production of fossil-free fuels, chemicals, andmaterials. Membrane filtration has been studied in the last decades as a key separation method torecover lignin from black liquor. Further studies to concentrate lignin using membrane filtration arerequired, as well as characterization of the resulting lignin fractions for the development of moleculartailored lignin-based applications.

In the present work, nanofiltration (NF) was used to concentrate and recover the low-molecularweightlignin obtained from the permeate of ultrafiltration of kraft black liquor. The concentration wasperformed using a NF090801 polymeric NF membrane (SolSep) with a molecular weight cut-off of 350Da. A transmembrane pressure of 25 bar and 50 °C during the filtration increased the lignin contentfrom 27 to 52 g/l, whereas a transmembrane pressure of 15 bar and 70 °C gave an increase from 18 to45 g/l in lignin content. The lignin fraction recovered in the retentate of the NF step was analyzed bysize-exclusion chromatography to ascertain the molecular weight of the lignin. Moreover, Fouriertransform infrared spectroscopy and thermogravimetric analysis were carried out to evaluate thethermal properties and functionalities of the obtained fractions.

Through our innovation, the product from a process that converts biowaste into a biofuel/biochar (HTC carbon) can be further refined into a bio-based high-value activated carbon and thus give the market an alternative to today's fossil activated carbon. When the bio-based activated carbon reaches the end of its life cycle, it is burned as a biofuel. This creates a carbon sink, which grows the more cycles the activated carbon is regenerated. When bio-based activated carbon gains market share from fossil activated carbon, the CO2 footprint decreases by about 10 tonnes of CO2/tonne of activated carbon. If all market shares worldwide are taken from fossil activated carbon, the CO2 footprint can be reduced by about 28 million tons/year. Different production methods to produce activated carbon from HTC carbon have been investigated within this project. One suitable method for producing activated carbon for gas applications and one for activated carbons for liquid applications have been developed. The properties of the produced qualities of activated carbon are not as good as the ones on the market today. However, there is potential for optimization so that an activated carbon with competitive quality can be produced from this renewable resource.