Start-up of anaerobic filters containing different support materials using pig slurry supernatant

Summary

Start-up of four laboratory-scale anaerobic filters, containing clay, coral, mussel shell and plastic pall ring support materials, was achieved at a hydraulic retention time of 6 days and a constant COD loading, ab initio, of 5 kg COD.m⁻³.d⁻¹ using a pig slurry supernatant feed. Start-up was most rapid with the clay filter (c. 20 days) and was slowest with the filter containing the mussel shell support. Irrespective of the time taken for start-up, the performance of all four filters at steady-state was similar, with COD removal efficiencies of 69–73% being attained. Start-up and steady-state performance did not correlate directly with either the unit surface area or the porosity of the support materials utilised.