Results - Technological Demonstration Centers (TDCs)

The tunisian TDC is located at the Institut National de Recherche Scientifique et Technique, Laboratoire Eau et Environnement (CERTE) in Tunis

The number of student houses is important in Tunisia and they lodge a growing number of students of approximately 69000 for the year 2005, equivalent to the population of a Tunisian city. The student house buildings present a facility of segregation of grey and black water since the showers or toilets are grouped in one space for common use. In addition these buildings have an important roof surface for rainwater harvesting.

The student house selected for the installation of the TDC is a public building of three floors for female engineering students (figure 1) of a capacity of 212 persons. The bath area is equipped with 18 showers and situated in the ground floor. Each floor has 10 wash-hand basins and 5 toilets.

Figure 1: General view of student house building

TDC layout

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The TDC scheme is divided into three lines of treatment relating to grey water, black water and rain water and three objectives of re-use for toilet flushing, landscaping and showering, respectively. Technologies to be established are membrane bioreactor MBR, (BUSSE GmbH, Germany), sequencing batch reactor SBR (PONTOS GMBH, Germany) and Constructed Wetlands. A research studies are conducted by Zer0-M partners to optimize and evaluate the performances of these technologies with respect to grey or black water.

Grey Water: The grey water is first introduced from a manhole to a tank serving as storage and homogenizing unit. Coarse and fine particles are removed by screens placed in the manhole and the holding tank. The designed flow is 1m3/d. Two technologies of treatment are selected, MBR and SBR. The principle of the SBR is a biological treatment in a compact reactor with different sequences (example: aerobic/anoxic/settlement) of which the order, the number and the duration are variable and have to be optimized according to the nature of the effluent. The disinfection of treated water is ensured by UV lamp.

Black water: The black water is introduced to a storage tank and then 1m3/day is treated in three chambers septic tank followed by horizontal subsurface flow (HSSF) and vertical subsurface flow (VSSF) constructed wetland. The treated water is stored in a tank for green area irrigation.

Rain water: The rainwater is collected from the roof of the student house building (approximately 600m2) in a storage tank (14 m3) after screening. The outflow of the storage tank discharges into sand bed for rainwater infiltration. The pumped water is filtered with sand filter and heated using solar energy before to be recycled to supply one shower. Sludge produced by the TDC is treated in a planted composting bed.

Monitoring results

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