Kinetics of piggery wastes treatment in anaerobic lagoons

Abstract

Results of laboratory studies of anaerobic lagoon performance have been analyzed to yield kinetic data applicable for design. None of the models currently used fitted the data. A novel interpretation has been proposed based on the dependence of effluent quality on volumetric organic loading. It is suggested that the removal takes place in consecutive stages at a progressively decreasing rate (expressed in kg m⁻³ day⁻¹). In the case of dilute piggery wastes from large farms the first stage of rapid sedimentation takes only a few hours and achieves some 55% removal of COD. The second stage, biochemical removal, proceeds at 1·7 kg COD m⁻³ day⁻¹ for about 3 days HRT and then the removal rate drops down to 0·2kg COD m⁻³ day⁻¹