This study was carried out the city of Outapi in North Namibia (Figure 18). In 2011, Outapi had a total population of 6,437 persons (NSA 2011). The population density is approximately 21.5 persons/ha (based on the approximate town area of 3 km², estimated using Google Earth (Version 7.1.2.2041) (2013)).
Figure 18 Overview on the study area of the CuveWaters project, the locations of the sub-projects and types of imple-mented facilities (ISOE (2013), Price and Hegnauer (2016), modified)
Together with local stakeholders, Outapi has been chosen as the location for a project on san-itation and water reuse (Deffner and Kluge 2013; Deffner and Mazambani 2010). This initia-tive is part of the interdisciplinary project “CuveWaters”. Its overall objecinitia-tive is the develop-ment and impledevelop-mentation of an integrated water resources managedevelop-ment for the Cuvelai-Etosha Basin in the north of Namibia (Kluge et al. 2008). The CuveWaters project is a joint research project funded by the German Federal Ministry of Education and Research (BMBF). Facilities for rainwater harvesting, groundwater desalination, subsurface water storage, and sanitation and water reuse were implemented at five locations in several sub-projects (Figure 18).
Project partners of the sub-project on sanitation and water reuse are the Institute for Social-Ecological Research (ISOE, Frankfurt, Germany), the Technische Universität Darmstadt (TUDa, Darmstadt, Germany), Bilfinger Water Technologies (BWT, Hanau, Germany), the Outapi Town Council (OTC, Outapi, Namibia), the Desert Research Foundation of Namibia
(DRFN, Windhoek, Namibia) and the Ministry of Agriculture, Water and Forestry (MAWF, Windhoek, Namibia).
Planning of the overall concept for sanitation and water reuse started in 2009 as a close coop-eration between the OTC, DRFN, TUDa, BWT and ISOE. To adjust the overall concept, and especially, the layout of the sanitation facilities to the needs of future users, several commu-
Figure 19 Schematic drawing of the concept for sanitation and water reuse in Outapi; elements in grey represent compo-nents that were not implemented as intended, UASB = upflow anaerobic sludge blanket, RBC = rotating bio-logical contactor
Figure 20 Location of the components of the sanitation system: cluster units (1), individually connected households (2), communal washhouse (3), water reuse plant with storage pond (4) and irrigation sites (5 and 6) (Google Earth (Version 7.1.2.2041) 2013)
nity workshops were organized and run by DRFN and ISOE (Deffner and Mazambani 2010).
A Namibian civil consultant was responsible for the detailed planning. Construction was car-ried out from 2011 to 2013 by a Namibian construction company. More details on the planning process, choice and dimensioning of wastewater treatment are provided in the results and dis-cussion section (Chapter 4.1, page 53ff.). This section focuses on the description of what was finally implemented by the project partners.
Figure 21 Layout of the communal washhouse (top, drawing provided by Lund Consulting Engineers, Windhoek), after start of construction in December 2011 (bottom, left) and after completion in May 2013 (bottom, right)
The infrastructure includes various types of sanitation facilities, a vacuum sewer system (RoeVac, BWT, see Section 2.7, page 28), a wastewater treatment plant with sedimentation and anaerobic pretreatment (ROEDIGER UASB reactors – upflow anaerobic sludge blanket, BWT), aerobic treatment and secondary clarification (RBC – rotating biological contactors and lamella clarifiers, System S&P, Dr. Scholz & Partner), microscreening (a drum-type mi-croscreen, 15 µm mesh width, PASSAVANTMicro Giant (MTSM) 1000 × 1000, PAN4-4711, BWT) and UV disinfection (low pressure UV lamps, LBX 50, WEDECO). The treated water is stored in a pond and applied to the agricultural fields via surface drip lines (Figure 19). The
Figure 22 Layout of one cluster unit (top, left, drawing provided by Lund Consulting Engineers, Windhoek), construction phase in December 2011 (top, right and bottom, left) and after completion in November 2013 (bottom, right)
reclaimed water is used for the production of vegetables for human consumption. An evapora-tion pond collects the drainage water from the fields, where it is dried by solar radiaevapora-tion. The sewage sludge is dried on sludge beds. After stabilization, the biosolids and nutrients are used on the agricultural fields.
Outapi is a fast-growing urban area with a very heterogeneous structure reflected in differently developed areas. It was clear from the beginning that one single type of sanitation facility could not serve the needs of all residents and suit all developmental stages. Thus, three different types of sanitation facilities were implemented in three areas at varying stages of development (Fig-ure 20). Up to 1,500 residents can benefit from this infrastruct(Fig-ure.
A larger, shared sanitation facility offers flush toilets, showers, hand wash basins and sinks for laundry washing on a pay-per-use basis to the community as well as to people from a nearby market place (Figure 21). It includes separate sections for male and female users and is located in a very recent, informal area of corrugated iron huts completely lacking any kind of water infrastructure at the time the project started. The communal washhouse was intended to serve up to 250 inhabitants. Operation started in April 2013 and security and maintenance staff was provided by the OTC. According to the definitions given in Norman (2011) (Figure 2), this facility can be characterized as a public facility because it is open to everybody on a
pay-per-use basis. However, since it is targeted towards servicing the community, it is referred to as
“communal washhouse” in this work.
Thirty smaller sanitation facilities (“cluster units”) are shared by three to five families each since November 2013. The area has a pre-formal layout. It is a neighborhood with provisional streets and buildings. The cluster units are equipped with an indoor shower, toilet and hand wash basin and an outdoor laundry sink (Figure 22). They are managed by the allocated house-holds. Showers and laundry sinks are equipped with prepaid water meters. Free access is given to toilets and the small hand wash basins. The costs for the water not billed for (toilets and hand washing) are cross-subsidized by the paid uses (showering and laundry washing).
Up to 66 households in a self-built neighborhood (a ‘pre-formalized’ area with brick houses) can be individually connected to water pipes and sewers (Figure 23). During the project dura-tion, 42 households were included in the sanitation system.
Figure 23 Buildings with individual connections to tap water supply and vacuum sewers