The aim of the present study was to assess the technological reliability of a domestic hybrid wastewater treatment installation consisting of a classic three-chambered (volume 6 m3) septic tank, a vertical flow trickling bed filled with granules of a calcinated clay material (KERAMZYT), a special wetland bed constructed on a slope, and a permeable pond used as a receiver. The test treatment plant was located at a mountain eco-tourist farm on the periphery of the spa municipality of Krynica-Zdrój, Poland. The plant's operational reliability in reducing the concentration of organic matter measured as BOD5 and COD, was 100% when modelled by both the Weibull and the lognormal distributions. The respective reliability values for total nitrogen removal were 76.8% and 77.0%, total suspended solids – 99.5% and 92.6%, and PO4-P – 98.2% and 95.2%, with the differences being negligible. The installation was characterized by a very high level of technological reliability when compared to other solutions of this type. The Weibull method employed for statistical evaluation of technological reliability can also be used for comparison purposes. From the ecological perspective, the facility presented in the study has proven to be an effective tool for protecting local aquifer areas.
- cold climate
- hybrid constructed wetland
- mountain aquifers
- rural areas
- technological reliability
- First received 11 November 2016.
- Accepted in revised form 21 February 2017.
- © IWA Publishing 2017