Upgrading Lagoon Effluents with Rock Filters

by Gregory R. Swanson, (A.M.ASCE), Grad. Student; Oregon State Univ., Corvallis, Oreg.,
Kenneth J. Williamson, (A.M.ASCE), Assoc. Prof.; Oregon State Univ., Corvallis, Oreg.,

Serial Information: Journal of the Environmental Engineering Division, 1980, Vol. 106, Issue 6, Pg. 1111-1129

Document Type: Journal Paper


Rock filtration is an effective, low-cost unit process for removing algae from effluents and correspondingly upgrading lagoon treatment. Sedimentation is the primary mechanism of algal removal within rock filter. A mathematical model of the sedimentation mechanism indicated that total suspendedsolids (TSS) removal efficiency is a function of the distribution of algal settling velocities, the hydraulic retention time, and the effective settling distance in the rock filter. Weekly average effluent biochemical oxygendemand (BOD5) and TSS from the Veneta, Ore, lagoon-rock filter treatment facility did not exceed 20 mg/L over a 1-yr study period. Settling rates of algae from the Veneta lagoon averaged about 0.05 my. A linear relationship between TSS removal efficiency and hydraulic loading rate was demonstrated.

Subject Headings: Lagoons | Effluents | Rocks | Filters | Vegetation | Hydraulic models | Velocity distribution | Hydraulic loads

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