Lignite clean up of magnesium bisulphite pulp mill effluent as a proxy for aqueous discharge from a ligno-cellulosic biorefinery

Pulp and paper mill effluent derived from an acidic magnesium bisulphite process was chosen to model industrial biorefinery process water effluents that are potentially rejected into the environment. This effluent consisted of high colour, organics and phosphorus load. Some treatments that have been reported to deal with organics and colour removal are photocatalysis, oxidation, electrocoagulation, biological treatments and adsorption. Among these, adsorption is still considered to be one of the simplest and economical methods. Activated carbon is probably the most prominent adsorbent applied in wastewater treatment. However, the high costs associated with its activation, regeneration and maintenance have significant drawbacks restricting its use. Lignite, a low rank coal, is a cheap and readily available material that has well known adsorption properties. Here we report on the use of Loy Yang (LY) lignite as an adsorbent and investigate its selectivity for colour, organics and total phosphorus removals from pulp and paper mill effluents. These results suggest the potential of lignite, as a cheap and readily available adsorbent, to be utilized in industrial biorefinery wastewater treatment.

► The process water of a bisulfite pulp mill was selected to model the effluent of an industrial biorefinery.
► We report the use of lignite as a low cost adsorbent and quantify its selectivity for colour, organics and phosphorus removal.
► The lignite has a higher capacity for phosphorus than activated carbon.