Physicochemical Behaviour of Polynuclear Aromatic Hydrocarbons in Primary Sedimentation. II. Pilot Scale Studies

Authors:
  • NBN. D. Bedding
    N. D. Bedding
  • PTP. N. Taylor
    P. N. Taylor
  • JLJ. N. Lester
    J. N. Lester
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Abstract
The removal behaviour of polynuclear aromatic hydrocarbons (PAH) during primary sedimentation was evaluated by means of a pilot plant operated at a range of hydraulic (6.10 – 61.0 m3 m−2 d−1) and suspended solids (SS) (300 – 1000 mgl−1) loadings. Mean removals increased with molecular weight (MW) from 21.3% (MW 128) to 63.0% (MW 228), and subsequently decreased to around 52.1% (MW 278) due to preferential association of high molecular weight PAH with small particles (< 53µm) of poorer settleability. PAH removal correlated with SS removal; low molecular weight hydrocarbon removal was dependent on SS loading and high molecular weight removal dependent on hydraulic loading. Regression functions were formulated relating PAH removal to tank performance, enabling prediction of effluent and sludge quality and permitting calculation of discharge limits to sewers to satisfy receiving water and sludge quality criteria.