Soil as a wastewater treatment system: historical development V.E. Tzanakakis, N.V. Paranychianaki and A.N. Angelakis Institute of Iraklio, National Agricultural Research Foundation, 71307 Iraklion, Greece (E-mail: vasilisj@mailbox.gr) Abstract “Land treatment” refers to the application of wastewater to the soil to achieve treatment and to meet irrigation needs of the vegetation. Application of wastewater to the land was the first practice used to protect public health and control environmental pollution. This technology has gone through different stages of development with time but it was not until 1840s when the basic principles of this technology started to establish. The use of land treatment for wastewater treatment declined after the development of conventional treatment plants but a renewed interested occurred after the passage of Clean Water Act and especially, during the last two decades. Currently, its application has been expanded in the management of various types of wastewaters including dairy, meat, industrial effluents as well as and polluted water sources. It is recognized as the ideal technology for rural communities, clusters of homes and small industrial units due to low energy demands and low operation and maintenance costs. Furthermore, in conjunction with biomass production can contribute in the control of climate change. A brief historical overview along with an introduction to the fundamental processes the current trends and the future prospects are provided in this section. Keywords History of land treatment; sanitation; wastewater management Introduction Land treatment is defined as “the controlled application of partially treated wastewater onto land to achieve treatment and disposal goals in a cost-effective manner” (Crites et al., 2000). Land application is the oldest practice used to manage wastewater and control environmental pollution. Historical evidence of wastewater spreading to the soil for crop irrigation and sanitation purposes goes back to the ancient cities and palaces of Minoan Civilization (Angelakis and Spyridakis, 1996; Angelakis et al., 2005). With the progress of time land treatment has gone through different stages of development but the basic prin- ciples regarding the planning, operation and management practices were developed after 1850 when the “sewage farms” were expanded in Europe and USA in an effort to control pollution and protect public health (U.S. EPA, 1979). The development of conventional wastewater treatment technologies in the turn of 19th century resulted in a decline of land treatment systems (Reed et al., 1995), but the interest was renewed after the passage of Clean Water Act in 1972 and particularly the last two decades. This is mainly due to the low construction, operation and maintenance costs, making this technology suitable for small communities or decentralized clusters of homes, institutions and isolated industrial units (Crites and Tchobanoglous, 1998; Angelakis, 2001). Different types of land treatment systems were developed through the passage of time depending on the rate of applied hydraulic load, the presence or absence of vegetation, the needs for preapplication treatment and the intended level of treatment. These include: slow rate systems (SR): these systems utilize soil matrix for treatment and the applied load is based on vegetation water requirements; overland flow (OF): they utilize soil surface and vegetation for treatment and the treated wastewater is collected as Water Science & Technology: Water Supply Vol 7 No 1 pp 67–75 Q IWA Publishing 2007 67 doi: 10.2166/ws.2007.008