Concentration of Metals In Recycled Papers, 1998 Recycling Symposium Proceedings

In pulping and papermaking, metal ions can cause deposit problems, brightness reversion, bleach decomposition,and environmental problems. The purpose of this research was to investigate the concentrations of metals entering and leaving a deinking mill.

Aluminum, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, nickel, and zinc were measured in five recycled paper grades and broke from a 100% recycled fiber mill. Metal concentrations were also measured in process water, mill effluents, wastewater effluent, and sludge. A metal mass balance over the

entire mill process suggested that all major sources and sinks of metals were accounted for.

Only l-12% of the metal entering the deinking mill went out with the product Most metals (75-100% of totals)entered the mill in the wastepaper and left in the wastewater sludge. Two-thirds to threequarters of the magnesium entered with process water and about half left with the wastewater discharge. Metal concentrations in wastewater effluent and sludge were well below regulatory limits. Differences between paper grades were the largest source of variation.