In recent years, many mills have reduced their water consumption to increase energy efficiency and conserve water resources. Such changes have affected the quality and quantity of the generated waste, but most mills have continued to use their original, now over-sized effluent treatment systems—a practice that is often neither cost-effective nor environmentally friendly.

FPInnovations has been working with member companies on projects to help meet current and future effluent treatment challenges, at the lowest possible operating costs. This includes one of FPInnovations’ member company mills, which faced the challenge of decreasing the moisture content of the dewatered effluent treatment residues (biosolids). This was specifically the case during winter months when the biological component of the residue stream was elevated.

Through laboratory studies, FPInnovations demonstrated that pretreatment of biosolids with an inexpensive dewatering aid could enhance the dewatering plant efficiency. Subsequently, the mill conducted a 14-day, full-scale trial this past winter, which confirmed the laboratory findings. The mill-scale trial showed a 4% increase in the solids content of the dewatered material (from 29% to 33%) and the potential to save up to one-half of the traditionally used dewatering polymer cost. The increased dewatering efficiency will allow the mill to combust the dewatered material without having to use auxiliary fuel, as compared to the past practice (paying for the moisture penalty due to poor dewatering). As well, the use of this approach will allow the mill to divert all of the biosolids away from landfill sites, through combustion in a power boiler.

For more information, please contact Talat Mahmood, Research Leader in FPInnovations’ Resources Management program, at talat.mahmood@fpinnovations.ca.