Recycled vertical flow constructed wetland (RVFCW)-a novel method of recycling greywater for irrigation in small communities and householdsIntroductionMaterials and methodsRecycled vertical flow constructed wetlandRecycled vertical flow constructed wetland performanceShort-term study ldquo Batch rdquo greenhouse studyLong-term case studyFeasibility analysisResults and discussionRVFCW design criteriaRVFCW performanceShort-term study ldquo Batch rdquo greenhouse studyLong-term case studyFeasibility analysisConclusionsAcknowledgementsReferencesRecycled vertical flow constructed wetland (RVFCW)—a novelmethod of recycling greywater for irrigation in small communitiesand householdsA. Grossa,*, O. Shmuelia, Z. Ronena, E. RavehbaDepartment of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Jacob Blaustein Institutes for Desert Research,Ben-Gurion University of the Negev, Sede Boqer Campus, 84990 Midreshet Ben-Gurion, IsraelbDepartment of Plant Science, Gilat Research Center, Mobile Post Negev 85280, IsraelReceived 19 February 2006; received in revised form 4 June 2006; accepted 6 June 2006Available online 17 July 2006AbstractThe use of greywater for irrigation is becoming increasingly common. However, raw greywater is often contaminated and can causeenvironmental harm and pose health risks. Nevertheless, it is often used without any significant pretreatment, a practice mistakenly con-sidered safe. The aim of this study was to develop an economically sound, low-tech and easily maintainable treatment system that wouldallow safe and sustainable use of greywater for landscape irrigation in small communities and households. The system is based on a com-bination of vertical flow constructed wetland with water recycling and trickling filter, and is termed recycled vertical flow constructedwetland (RVFCW). The RVFCW’s properties, removal efficiency, hydraulic parameters and feasibility were studied, as well as the envi-ronmental effects of the treated greywater, as reflected by soil and plant parameters over time. The RVFCW was efficient at removingvirtually all of the suspended solids and biological oxygen demand, and about 80% of the chemical oxygen demand after 8 h. Fecal col-iforms dropped by three to four orders of magnitude from their initial concentration after 8 h, but this was not always enough to meetcurrent regulations for unlimited irrigation. The treated greywater had no significant negative impact on plants or soil during the studyperiod. The feasibility analysis indicated a return over investment after approximately three years. We concluded that the RVFCW is asustainable and promising treatment system for greywater use that can be run and maintained by unskilled operators. 2006 Elsevier Ltd. All rights reserved.Keywords: Vertical flow constructed wetland; Wastewater reuse; Greywater treatment; Environmental pollution1. IntroductionThe quantity of freshwater available worldwide isdeclining, raising the pressing need for its more efficientuse. One method of conserving water is by recycling grey-water (GW) for irrigation. GW is dom estic wastewater thatincludes only wash water (i.e., bath, dish, and laundrywater), whereas blackwater consists of toilet water. Dueto the substantial difference in their qualities, separatingGW and blackwater would provide for more effectivewastewater treatment, allowing a large volume of waterto be efficiently recycled (Lindstrom, 2000). This is partic-ularly important in arid zones, were water is scarce andrecycling GW for private and public landscape irrigationcould reduce potable water use by up to 50% (DHWA,2002). The use of GW for private garden irrigation isbecoming increasingly common. In most countries, regula-tions or specific guidelines for GW reuse are not available,and it is therefore often used without any significant pre-treatment, a practice mistakenly considered safe. In coun-tries such as the USA and Australia, where regulationsfor the use of GW have been established, they concentrateon issues associated with public health but do not considerpotential harmful environmental impacts (Dixon et al.,1999; DHWA, 2002; ADEQ, 2003). The separation of the0045-6535/$ - see front matter 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.chemosphere.2006.06.006*Corresponding author. Tel.: +972 8 6596896; fax: +972 8 6596909.E-mail address: [email protected] (A. Gross).www.elsevier.com/locate/chemosphereChemosphere 66 (2007) 916–923toilet stream from domestic wastewater generates effluentswhich have reduced levels of nitrogen, solids, and organicmatter (especially the barely degradable fraction), but oftencontain elevated levels of surfactants, oils, boron and salt.The components in GW may alter soil properties, damageplants and contaminate groundwater (Garland et al., 2000;Gross et al., 2005; W iel-Shafran et al., 2006). A studyaimed at applying commercial systems to GW reuse inhouseholds demonstrated, in five different commercial sys-tems, failure to treat the GW sufficiently for unlimited use(Gross et al., 2003). That study also suggested that this wasso, either because the treatment was too superficial (as thewater is considered safe by many), or because it was adownscaled wastewater treatment system rather than aGW treat ment system aimed at treating small volumes inprivate houses.The aim of the current study was to develop aneconomically sound, low-tech and easy-maintenancetreatment system that would allow safe and sustainableuse of GW for landscape irrigation in small communitiesand households.2. Materials and methods2.1. Recycled vertical flow constructed wetlandThe proposed treatment method is a modification of thevertical flow constructed wetland (VFCW) describedby IWA (2000), with a novel set-up. Initially, the systemwas composed of two containers (0.95 m W · 0.95 ml ·0.55 mH; about 500 l each) placed one above the other:(1) the upper one was a VFCW composed of a three-layerbed consisting of 15 cm planted organic soil over a 30 cmlayer of tuff or plastic media and a 5-cm lower layer oflimestone pebbles. The bottom of the bed’s compartmentwas perforated; (2) the lower container was used as a waterreservoir, located directly beneath the VFCW (Fig. 1).The raw GW flowed through a sedimentation tankwhich accounted for about 10% of the total system volumeand where only coarse material settled. From this tank itwas pumped or overflowed into the root zone of
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