Modern kraft pulp mills produce on average about 100 kg of solid waste per ton of pulp produced. The most significant types of mill waste are sludge from wastewater treatment, ash from biomass combustion and dregs, grits and lime mud from the causticizing plant and lime dust from the lime kiln. Presently about half of the mill waste is disposed of on landfills, which highlights the need and the potential for waste recycling and utilization. A significant portion of the sludge generated in pulp and paper mills is utilized either by incineration in hogfuel boilers to generate steam and power, or by various forms of land application including land spreading, composting, or as additive for landfill or mine waste covers. However, the majority of alkaline wastes, mainly hogfuel boiler ash and causticizing plant residues, are currently landfilled. Alkaline wastes can be suitable for land application in agriculture and forestry, for the manufacture of construction material, as well as for road and earth construction.
展开▼
