Treatment of a pulp and paper mill wastewater to achieve effluent re-use: a case study

摘要

This paper describes a study undertaken at the Shotton Paper Mill to tertiary treat effluent from an existing activated sludge plant to achieve a quality compatible with the existing mill fresh water quality, with a current use of around 18,000 m~3d~(-1) of fresh water. The study comprised of: optimisation of the existing activated sludge plant to increase COD removal; investigation of anaerobic treatment as pre-treatment to remove the high sulphate concentration in the wastewater; tertiary treatment using chemical coagulation to remove colour and residual COD; and finally, electrodialysis reversal for desalination. The final treatment train was trialled at a pilot scale plant and was able to produce a product with a TOC <10 mg l~(-1) and conductivity < 500 μSi cm~(-1); this was of a quality similar to that of the fresh water source.