CATALYTIC WET OXIDATION OF THERMOMECHANICAL PULPING SLUDGE

The use of various metal salts as catalysts in a wet oxidation (WO) fo r the treatment of sludge from a thermomechanical pulping (TMP) mill w as investigated After selecting a suitable catalyst, further experimen ts were performed to study the effect of oxygen pressure, temperature, rime of reaction, non catalyst concentration. Experiments were carrie d out in a stainless steel batch reactor rising pure oxygen and sludge from the primary clarifier of a TMP mill. The screening experiments s howed that tile best catalyst was copper sulphate (CuSO4). When using this catalyst, a 97.6% reduction in the chemical oxygen demand (COD) o ccurred compared to a 76.5% reduction without catalyst under the same conditions of temperature (212 degrees C) and presssure (11.5 Mpa, 167 0 psi). The catalyst increased the degree of oxidation, resulting in d ecreased production of low-molecular weight organic compounds such as acetic acid. The results indicate that the addition of copper sulphate (5 mmol/L) significantly improves the treatment of TMP sludge by wet oxidation.