Concentration of retene and resin acids in sedimenting particles collectedfrom a bleached kraft mill effluent receiving lake

The concentration of retene, a di-alkyl substituted PAN derived microbially and thermally from dehydroabietic acid, eight resin acids and their deriva tives were analysed from sedimenting particles collected from five lake sit es receiving pulp and paper mill effluents and from two reference sites. At five of the sites, samples were collected prior and after a conventional a erated lagoon wastewater treatment system of the mill was modernized with a n activated sludge plant, and elemental chlorine free bleaching (ECF) had r eplaced chlorine bleaching. The highest level of retene was 30.0-53.5 mu g/ g dry weight (d.w.), observed 3 km downstream from the mill. Nine kilometer s downstream from the mill the concentration of retene was still 8.7-17.4 m u g/g d.w., distinctly exceeding that of the upstream reference (0.2-4.4 mu g/g d.w). The highest concentration of resin acids was 1474 mu g/g d.w., t he most abundant resin acid bring dehydroabietic acid. The concentrations o f retene and resin acids showed a distance related decrease downstream to a mill. The technology changes at the pulp and paper mill decreased both the sedimentation rate and the concentration of resin acids and retene in sedi menting particles. Presence of other resin derived neutral compounds (dehyd roabietin, tetrahydroretene and fichtelite) in sedimenting particles was al so revealed. (C) 2000 Elsevier Science Ltd. All rights reserved.