A new approach for local waste water management sanitation case study of rural school (Chorfech 24)

The millennium objectives are reduction by half, before 2015, the rate of the population which has no access to the drinking water and to the basic sanitation. Tunisia will reach these goals at the national level as regards the potable water supply; on the other hand uncertainties persist to reach these goals for the basic sanitation, particularly in rural areas. Forty percent of the Tunisian population lives in rural areas in small villages or isolated habitat with an access to drinking water, but 83% of them still have very poor sanitation services and their wastewater is discharged directly in the nature without treatment. The sanitation network is absent; and 13.5% of them have sanitary pit or septic tank (Sellami et al. 2007). To set up a strategy and to help the government to identify the best sanitation solutions for small settlements, several experiences were conducted by researchers in Tunisia (Sellami et al. 2007; Kouki et al. 2009; Ghrabi et al. 2011, Ben Saad (2012)).

The purpose of this paper is to present case study of wastewater management approach in rural area in Tunisia (primary school), implemented by Centre of Water Research and Technologies (CERTE). The design and the implementation of the solution have been developed in close consultation with the stakeholders and national authorities managing school and sanitation in Tunisia. The objectives of this study is to solve the problems of the uncontrolled wastewater discharged into nature without treatment, and to set up a robust solution to be recommended for application in rural school in Tunisia, devoid of sanitation system and characterized by limited financial resources for water supply and sanitation services.

The sanitation system consists of septic tank followed by horizontal subsurface flow constructed wetland (Figure 2). The treated wastewaters are used for garden irrigation of the school, planted by fruit trees (fig and pomegranate) and flowers. The irrigation is applied by an automatic underground drop-by-drop system. Basing the data collected and experiments conducted, 3 years before and after implementation of the solution, we present the preliminary results of evaluation.

The evaluation is based in water pollution parameters (pH, TSS, COD, BOD, Nitrogen, Phosphate, Fecal coliform and E. Coli). The standard methods are used (APHA/AWWA/WEF 2005).

Since 2005, school has contained seven teachers and a number of students between 65 and 74 students per year. Table 1 shows the different volumes of consumed water of the school before and after the implementation of sanitation system. Before implementation of the system, the average consumption of drinking water in school is more than 21 L/day.pupil. After, this consumption decreases more 50% (10.7 L/day.pupil); see Table 1.

Table 2 presents the performance of the sanitation system implemented in the Chorfech 24 primary school. The average of overall removal rates of sanitation system ‘septic tank – constructed wetland’ have been, respectively, equal to 93% for total suspended solids (TSS), 86,7% for chemical oxygen demand (COD), 96,4% for biochemical oxygen demand (BOD₅), 68% for NH₄⁺, 71% for NTK, 88,5% for PO₄.

The results show the feasibility of the system composed by septic tank and horizontal subsurface constructed wetland. Regarding the high removal rates obtained, the final quality of treated effluent could be sufficient for garden irrigation. Rainwater could provide an alternative as well as the installation of water saving devices. The pilot activity will also build and reinforce the capacity building and expertise related to the implemented techniques under real conditions. This solution can be recommended for wide application in rural school in Tunisia and could be replicated in similar areas and countries in order to save water and to efficiently treat domestic wastewater avoiding direct discharge of untreated wastewater.

The sanitation system of primary school was developed and erected in the project ‘Sustainable Concepts towards a Zero Outflow Municipality (Zer0-M)’ and the monitoring was conducted in the FP4BATIW project (www.fp4batiw.eu), both funded by the European Union in the frame of MEDA Water and FP7, respectively.