Credit System Claims against the Fibre Actually inside the Box
Paperboard credit systems balance financial ledgers rather than physical fibers, requiring buyers to separate administrative certificates from batch fiber testing.
White Water Carryover
Definitional Water
Process water containing dissolved solids and fine fibres is transferred from one part of the papermaking system to another. Managing white water carryover is necessary for maintaining the chemical balance and efficiency of the mill’s water circuits. It occurs when the liquid that drains through the forming wire is reused in earlier stages of the process.
Contaminant Accumulation
If the water is not properly clarified, the concentration of fines and chemicals can increase over time. This white water carryover can lead to the buildup of slime and deposits that eventually cause holes or breaks in the paper sheet.
Environmental Impact
Reducing the amount of fresh water used requires the extensive recycling of process water, but this increases the risk of carryover issues. Effective filtration and the use of retention aids help to keep the valuable fibres in the sheet to prevent them from entering the water system. When white water carryover is not controlled, it can interfere with the effectiveness of wet end chemicals and increase the cost of wastewater treatment.
Balancing the water loop is a complex task that requires constant monitoring of the conductivity and pH levels. This stability is necessary for producing a consistent grade of paper while minimizing the environmental footprint of the mill.