Ecological Engineering 44 (2012) 337–343 Contents lists available at SciVerse ScienceDirect Ecological Engineering j ourna l ho me page: www.elsevier.com/locate/ecoleng Short communication A small-size vertical flow constructed wetland for on-site treatment of household wastewater Georgios D. Gikas, Vassilios A. Tsihrintzis ∗ Laboratory of Ecological Engineering and Technology, Department of Environmental Engineering, School of Engineering, Democritus University of Thrace, 67100 Xanthi, Greece a r t i c l e i n f o Article history: Received 11 October 2011 Received in revised form 31 March 2012 Accepted 8 April 2012 Available online 10 May 2012 Keywords: On-site wastewater treatment VF constructed wetlands HSF constructed wetlands Zeolite Organic matter Nitrogen Phosphorus k–C* model a b s t r a c t The design and performance of a small-scale vertical flow constructed wetland (VFCW) system, for on-site treatment of domestic wastewater, are presented. The system serves a two-story, two-family (8 persons) building, and comprises three treatment stages: two settling tanks in series, a VFCW and a zeolite tank. The treatment performance of the system was monitored on a weekly basis for about forty months. Results show a satisfactory performance with the following mean removal efficiencies: 96.4% for BOD, 94.4% for COD, 90.8% for TKN, 92.8% for ammonia, 61.6% for OP and 69.8% for TP. The zeolite was found to offer additional removal of nitrogen, total phosphorus and organic matter. The zeolite saturation time is estimated. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Constructed wetland (CW) technology for wastewater treat- ment is a relatively new technology, characterized by efficiency in pollutant removal, simplicity, and low construction and operation costs (Kadlec and Wallace, 2009; Vymazal et al., 1998). Constructed wetland systems are used in many countries, serving relatively small settlements, i.e., of the order of 1000 person equivalent (p.e.). A small number of full-scale CW systems operate in Greece (Gikas et al., 2007, 2011; Tsihrintzis et al., 2007; Tsihrintzis and Gikas, 2010). Several studies were completed showing the effectiveness of CW systems in wastewater treatment under Mediterranean cli- mate conditions (Akratos and Tsihrintzis, 2007; Akratos et al., 2008, 2009a,b; Kotti et al., 2010; Stefanakis and Tsihrintzis, 2012a). Recent CW applications for domestic wastewater treatment also include the service of isolated houses (4–10 people), mostly located in agricultural and ecologically sensitive regions, or where there is no possibility of house connection to a public wastewater treatment system (Brix et al., 2003; Gikas and Tsihrintzis, 2010; Zakova and Zak, 2003). Such systems are usually of the horizontal subsurface flow (HSF) or vertical flow (VF) CW type, varying in ∗ Corresponding author. Tel.: +30 25410 79393; fax: +30 25410 79393; mobile: +30 6974 993867. E-mail addresses: tsihrin@env.duth.gr, tsihrin@otenet.gr (V.A. Tsihrintzis). surface areas from 3 to 6 m 2 /p.e. and planted with Phragmites aus- tralis (Brix and Arias, 2005). Usually, two or three settling tanks are placed before the CW for pretreatment of influent (Börner et al., 1998; Vymazal, 2001; Zakova and Zak, 2003). This paper describes the design and construction details of the on-site wastewater treatment system for a two-family house in Avdira, Xanthi, Northeast Greece, and presents performance results from its 40-month monitoring under Mediterranean climate con- ditions. 2. Materials and methods 2.1. Facility description The on-site CW was built to treat the sewage from a two-family residence of 8 people in Avdira, a village in Xanthi district, North- east Greece (40 ◦ 58 ′ 49.6 ′′ N, 24 ◦ 56 ′ 52.8 ′′ E; Elevation 74 m). This system consists of two settling tanks in series (ST1 and ST2), a vault with a pump (ST3), a vertical flow CW, a zeolite tank (ZT), and an effluent collection tank (Fig. 1). From the residence, the wastewater inflows to the first settling tank (ST1), which overflows to the sec- ond one (ST2) and then to the pump vault (ST3). The dimensions of ST1 and ST2 are 1.3 m by 1.3 m in plan view. The operation depth is 1.5 m. The dimensions of ST3 are 0.7 m by 0.7 m in plan view. The operation depth is 1.5 m (Fig. 1). In the vault (ST3), a pump is used to discharge approximately every 3 h 150 L of wastewater onto the 0925-8574/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ecoleng.2012.04.016