Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.


Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 649-661 in On-Site Wastewater Treatment, Proc. Ninth Natl. Symp. on Individual and Small Community Sewage Systems (11-14 March 2001, Fort Worth, Texas, USA), ed. K. Mancl., St. Joseph, Mich. ASAE  701P0009.(doi:10.13031/2013.6070)
Authors:   J. Henneck, R. Axler, B. McCarthy, S. Monson Geerts, S. Heger Christopherson, J. Anderson, J. Crosby
Keywords:   Constructed wetlands, wastewater, alternative technologies, cold-climate

About 30 % of Minnesotans use on-site systems for wastewater treatment (~500,000 residences). Unfortunately, 55-70 % are failing or out of compliance with state standards. Homeowners and small businesses require cost-effective options in locations with restrictive soil and site conditions. In particular, many sites occur near lakes and streams creating a health hazard and deteriorating water quality. Constructed wetlands (CWs) are one option being evaluated and this paper addresses CWs as a viable wastewater treatment option in Minnesota based on experiences at three research sites, encompassing 5 subsurface flow wetlands from 1995-2000. These are small flow (<1000 gpd) subsurface flow gravel beds located at the Northeast Regional Correction Center (NERCC), Grand Lake, and Lake Washington, MN. Performance monitoring shows that CWs are a viable, year-round onsite treatment option. The systems were generally able to achieve design criteria of 30 mgBOD5/L, 25 mgTSS/L and 200 fecal cfu/100mL, although the NERCC CWs required 30 cm. of unsaturated soil to achieve consistent disinfection. High strength (~300mgBOD/L and 100mgTN/L) influent at NERCC probably limited system performance, particularly N-removal which was ~40% in summer and ~20% in winter (mass-based). Declining P-removal at the oldest sites suggest substrate saturation. Although CWs remain a viable option for homeowners in terms of performance, ease of operation, and cost, other issues relate to inconsistent vegetation growth (affecting performance and freezing), and meeting concentration-based regulatory standards since they may exhibit substantial variability due to rain events, partial freezing, spring snowmelt, and summer evapotranspiration.

(Download PDF)    (Export to EndNotes)