Successful trial on dewatering effluent treatment residues
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, Pointe Claire, QC, through its resources management program, has been working with member companies to help meet current and future effluent treatment challenges, at the lowest possible operating costs.
One such member company mills faced the challenge of decreasing the moisture content of its dewatered effluent treatment residues (biosolids). This was specifically the case in the winter when the biological component of the residue stream was elevated.
Laboratory studies at 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 winter trial 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 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 approach will allow the mill to divert all of the biosolids away from landfill sites through combustion in a power boiler.