Optimizing Aqueous Dispersion Coatings for Standard Paperboard Repulping Operations
Aqueous dispersion coatings require high carboxyl content and precise Tg control to fragment into screenable flakes rather than tacky micro-stickies during pulping.
White Water COD
Effluent Load
Dissolved organic compounds originating from mechanical pulping and secondary fibre dispersion impose a high chemical oxygen demand in mill white water circuits. Chemical oxygen demand measures the total mass of oxygen consumed during the oxidation of soluble and insoluble organic matter present in aqueous process streams. Unchecked organic accumulation in recycled water loops fouls biological treatment units and disrupts sizing chemistry on the paper machine wet end.
Effluent management protocols track white water COD concentrations to maintain biological stability before discharge into municipal or aquatic receivers.
Oxidation Demand
Soluble carbohydrates, lignin derivatives, and hemicellulose fragments enter process waters from high shear refining zones. Residual pulping agents and sizing additives compound the load during recycled fibre processing. High oxidant concentrations deplete dissolved oxygen in receiving aquatic systems if biological treatment fails to degrade the dissolved burden.
Mill operators monitor oxidant demand continuously to adjust coagulant dosing rates and optimize primary clarification efficiency.
Process Balance
Effective closure of white water loops concentrates organic residues and accelerates scaling risks across piping networks. Elevated chemical oxygen demand accelerates microbial slime growth on forming fabrics and press felts. Closed loop recycling strategies require precise oxidant monitoring to prevent corrosion and deposit formation on stainless steel components.
Balancing organic loading rates protects paper machine runnability while meeting environmental compliance limits.