Upflow anaerobic sludge blanket and aerated constructed wetlands for swine wastewater treatment : a pilot study

Swine wastewater management is often affected by two main issues: a too high volume for optimal reuse as a fertilizer and a too high strength for an economically sustainable treatment by classical solutions. Hence, an innovative scheme has been tested to treat swine wastewater, combining a low cost anaerobic reactor, upflow anaerobic sludge blanket (UASB), with intensified constructed wetlands (aerated CWs) in a pilot scale experimental study. The swine wastewater described in this paper is produced by a swine production facility situated in North Italy. The scheme of the pilot plant consisted of: (i) canvas-based thickener; (ii) UASB; (iii) two intensified aerated vertical subsurface flow CWs in series; (iv) a horizontal flow subsurface CW. The influent wastewater quality has been defined for total suspended solids (TSS 25,025 +/- 9,323 mg/l), organic carbon (chemical oxygen demand (COD) 29,350 +/- 16,983 mg/l), total reduced nitrogen and ammonium (total Kjeldahl nitrogen (TKN) 1,783 +/- 498 mg/l and N-NH4+ 735 +/- 251 mg/l) and total phosphorus (1,285 +/- 270mg/l), with nitrates almost absent. The overall system has shown excellent performances in terms of TSS, COD, N-NH4+ and TKN removal efficiencies (99.9%, 99.6%, 99.5%, and 99.0%, respectively). Denitrification (N-NO3- effluent concentration equal to 614 +/- 268 mg/l) did not meet the Italian quality standards for discharging in water bodies, mainly because the organic carbon was almost completely removed in the intensified CW beds