Environmental Development with Increased Production. Use of Tertiary Treatement in (DAF) in the Last Stage of the Wastewater Treatment System at Braviken..., 1997 Environmental Conference Proceedings

Holmen Paper AB operates a 700,000 admt/a TMP-Deink Pulp Newsprint Mill at Norrkoping, Sweden. Mill effluent was previously treated in an aerated lagoon following primary treatment. Increased production, from 430,000 admt/a to 700,000 admt/a, (new deinking line and paper machine) and new, more strict regulations based on COD and phosphorus forced the mill to convert the aerated lagoon to an activated sludge treatment system and finally to add a tertiary treatment system before discharge into the Baltic Sea. Holmen Paper elected to install tertiary dissolved air flotation treatment based on laboratory and pilot test results. The tertiary treatment system which treats a flow of 31,500 m 3 /d and 5,000-6,000 kg/day of COD, was installed and commissioned in April of 1996. The tertiary treatment utilizes alum and polymer for coagulation and flocculation. The results of the treatment are a reduction in COD from 150-200 mg/l following secondary treatment to 60-100 mg/l and total phosphorus from 2 mg/l to 0.2 - 0.4 mg/l.