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Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright http://www.elsevier.com/copyright Author's personal copy Resources, Conservation and Recycling 55 (2010) 221–231 Contents lists available at ScienceDirect Resources, Conservation and Recycling journa l homepage: www.e lsev ier .com/ locate / resconrec Treated wastewater reuse in South Africa: Overview, potential and challenges J.R. Adewumia,∗, A.A. Ilemobadea, J.E. Van Zylb a School of Civil and Environmental Engineering, University of the Witwatersrand, Johannesburg, Private Bag 3, WITS. 2050, South Africa b Department of Civil Engineering, University of Cape Town, South Africa a r t i c l e i n f o Article history: Received 8 September 2009 Accepted 25 September 2010 Keywords: Wastewater reuse Arid Non-drinking water requirements a b s t r a c t Many communities in South Africa struggle to access reliable and adequate quantities of potable water for diverse water requirements. This is against the backdrop of decreasing freshwater availability and increasing water demands. Currently, interest in the reuse of wastewater for non-drinking water require- ments is increasing. This paper therefore provides an overview of the South African water resources situation and wastewater1 generation in order to put the need for wastewater reuse into perspective. Potential for broader implementation and parameters influencing wastewater reuse based on local atti- tudes and experience were discussed with recommendations to facilitate broader implementation of wastewater reuse. This paper concludes that significant potential exists for implementing wastewater reuse for large non-drinking applications (e.g. landscape irrigation and industrial processes) in arid areas of South Africa especially Western Cape Province. Parameters highlighted from local attitudes and experi- ence to influence broader implementation in addition to aridity include distance from source, retrofitting versus new installations, quantity of reuse, tariffs, source quality, public health, willingness, public trust and knowledge, and regulations and guidelines for reuse. Prior to implementation, it is recommended that these parameters be addressed. © 2010 Elsevier B.V. All rights reserved. 1. Background and motivation South Africa is a semi-arid country with high water stress (40–60%) due to the low volumes of rainfall (average of 500 mm per annum) and high evaporation (average of 1700 mm per annum) (Eberhard and Robinson, 2003). The highly variable and spatial dis- tribution of rainfall across the country adds to the scarcity of fresh water. South Africa depends on surface water for most of its urban, industrial, and agricultural requirements with about 320 dams pro- viding a total capacity of about 32,412 × 106 m3 (DWAF, 2004a). Groundwater plays an important role but mostly in rural water supply schemes, with only a few groundwater aquifers that can be utilised on a large scale due to groundwater salinity in especially the coastal areas of the country (Mukheirbir, 2005). To manage existing water resources therefore, the country’s hydrological basins have been divided into 19 water management areas (Fig. 1) with mean annual runoff of approximately 49,040 × 106 m3/a. This includes water inflows of about 4800 × 106 m3/a and 700 × 106 m3/a origi- nating from Lesotho and Swaziland respectively (DWAF, 2004a). ∗ Corresponding author. Tel.: +27 117177101; fax: +27 865535330. E-mail addresses: James.Adewumi@students.wits.ac.za, jradewumi@gmail.com (J.R. Adewumi). 1 Wastewater refers to domestic, institutional, and industrial liquid waste prod- ucts collected through networks of pipes (sewers) into treatment plant. 1.1. Current water yield and requirements Surface water yield in rivers as shown in Table 1 was computed as 10,240 × 106 m3/a using mass curve analysis of the available reservoirs (dams) at 98% assurance of supply. To satisfy ecologi- cal flow requirements, 20% of the flow is assumed to remain in rivers to maintain a healthy biophysical environment. The Annual groundwater harvest potential is derived from an evaluation of the mean annual recharge of groundwater (adjusted for drought period rainfall). This gives an indication of the maximum vol- ume of groundwater that may be abstracted without depleting the aquifers as 1088 × 106 m3/a. The numerical data given in Table 1 with respect to yield and available water is therefore accepted as being of relatively high reliability. However, the figures are sub- ject to review in future as some of the influencing factors change and as new extreme climatic events are observed over time (DWAF, 2004a). The difference between the mean annual runoff (49,040 × 106 m3/a) and the total freshwater yield from sur- face and groundwater sources (11,328 × 106 m3/a) (Table 1) shows the significant effect that river losses (due to evaporation and seepage) have on freshwater availability in South Africa. The neg- ative yields from surface water in the Middle Vaal, Lower Vaal and Lower Orange water management areas reflect the fact that river losses are greater than the additional yield contributed by local runoff in these areas. Usable return flows (i.e. treated wastewater), 0921-3449/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.resconrec.2010.09.012 Author's personal copy 222 J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 Table 1 Available yield from water management areas in 2000 (DWAF, 2004a). Water management area Freshwater source (million m3/a) Usable return flows (million m3/a) Total local yield (million m3/a) Surface water Ground water Irrigation Urban Mining and bulk industrial Limpopo 160 98 8 15 0 281 Luvuvhu/Letaba 244 43 19 4 0 310 Crocodile West and Marico 203 146 44 282 41 716 Olifants 410 99 44 42 14 609 Inkomati 816 9 53 8 11 897 Usutu to Mhlatuze 1019 39 42 9 1 1110 Thukela 666 15 23 24 9 737 Upper Vaal 598 32 11 343 146 1130 Middle Vaal (67) 54 16 29 18 50 Lower Vaal (54) 126 52 0 2 126 Mvoti to Umzimkulu 433 6 21 57 6 523 Mzimvubu to Keiskamma 777 21 17 39 0 854 Upper Orange 4311 65 34 37 0 4447 Lower Orange (1083) 24 96 1 0 (962) Fish to Tsitsikamma 260 36 103 19 0 418 Gouritz 191 64 8 6 6 275 Olifants/Doring 266 45 22 2 0 335 Breede 687 109 54 16 0 866 Berg 403 57 08 37 0 505 Overall 10,240 1088 675 970 254 13,227 which comprise about 14% of the overall yield and approximately double the groundwater yield, are indirectly reused for potable supply i.e. extracted by drinking water treatment works from surface waters after discharge from wastewater treatment works (WWTWs) a distance upstream. With the aridity of the region and the substantial quantities of usable return flows generated daily, this paper argues for the direct reuse of these return flows for some non-drinking applications. In relation to water use, six broad categories totalling 12,871 × 106 m3/a (Table 2) were published by DWAF (2004a) i.e. rural (domestic and stock watering), urban (domestic, commer- cial and public), mining and industry, power generation, irrigation and afforestation. Irrigation makes up approximately 62% of the total water used and hence, any water savings in this sector will be beneficial to other needy sectors. Total water requirement of 12,871 × 106 m3/a (Table 2) is noticeably close to the estimated overall yield of 13,227 × 106 m3/a (Table 1) with water deficits existing in more than half of the water management areas, whilst a surplus still exists for the country as a whole (Table 3). In several cases, the deficits shown do not imply that present use exceeds available yield, but rather that the ecological reserve is not fully met (DWAF, 2004a). Also, inter basin transfers are often employed to address water supply shortfalls (Mukheirbir, 2005). Fig. 1. Map of South Africa showing water management areas (DWAF, 2004a). Author's personal copy J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 223 Table 2 Water requirement (million m3/a) in the various sectors in 2000 (DWAF, 2004a). Water management area Irrigation Urban Rural Mining and industry Power generation Afforestation Total requirement Limpopo 238 34 28 14 7 1 322 Luvuvhu/Letaba 248 10 31 1 0 432 333 Crocodile West and Marico 445 547 37 127 28 0 1184 Olifants 557 88 44 94 181 3 967 Inkomati 593 63 26 24 0 138 844 Usutu to Mhlatuze 432 50 40 91 0 104 717 Thukela 204 52 31 46 1 0 334 Upper Vaal 114 635 43 173 80 0 1045 Middle Vaal 159 93 32 85 0 0 369 Lower Vaal 525 68 44 6 0 0 643 Mvoti to Umzimkulu 207 408 44 74 0 65 798 Mzimvubu to Keiskamma 190 99 39 0 0 46 374 Upper Orange 780 126 60 2 0 0 968 Lower Orange 977 25 17 9 0 0 1028 Fish to Tsitsikamma 763 112 16 0 0 7 898 Gouritz 254 52 11 6 0 14 337 Olifants/Doring 356 7 6 3 0 1 373 Breede 577 39 11 0 0 6 633 Berg 301 389 14 0 0 0 704 Total for country 7920 2897 574 755 297 428 12,871 62% 23% 4% 6% 2% 3% 100% 1.2. Future water requirements Many factor such as climate, economic growth (i.e. irrigated agriculture and industrialization) and standards of living influence the requirements for water in South Africa. The major changes in national policies since 1994 have influenced migration into urban area and decline in population of rural areas. However, negative impact of HIV/AIDS on the country is a clear indication that future population cannot be a simple extension of the past. Detailed study of the demographic and socio-economic changes in the country shows that there is lower population growth rate than previous years (DWAF, 2004a). Estimation of future water demand was based on the division of the entire country into smaller geographic units with great attention given towards urbanisation and the expected stronger economic growth in the major urban and indus- trial estate. Low and high economic growth scenarios for different geographic regions of the country were developed and analysed. The result (Table 4) shows an upper scenario of average growth in GDP of over 4% per year for the period up to 2025, and a less favourable low growth scenario of 1.5% per year (DWAF, 2004a). Climate variability due to global warming could lead to reduction in stream flow by as much as 10% by 2025 in South Africa (Mukheirbir, 2005). Whilst the effect of climate change has been observed and acknowledged internationally, the effect of likely changes in cli- mate on water resource is yet to be fully established in South Africa, hence, it was not included in the future water requirements estima- tion. However, in anticipation of possible climatic change, special attention has been given to it in catchment monitoring program of DWAF (DWAF, 2004a). With the aridity of the region, water use approaching water yield and the incessant pollution of surface and groundwater resources, municipalities are challenged to explore alternative sources and efficiently manage water use and supply. Few municipalities have been proactive in these initiatives. However, some municipalities, for instance in the Western Cape Province, have implemented sev- eral demand management mechanisms to curb growing demands in the face of declining freshwater availability. These include water restrictions, pressure management, monitoring of water usage, Table 3 Available yield versus water requirement from water management areas in 2000 (DWAF, 2004a). Water management area Total local yield (million m3/a) Total requirement (million m3/a) Differences (million m3/a) Surplus Deficit Limpopo 281 322 41 Luvuvhu/Letaba 310 333 23 Crocodile West and Marico 716 1184 468 Olifants 609 967 358 Inkomati 897 844 53 Usutu to Mhlatuze 1110 717 393 Thukela 737 334 403 Upper Vaal 1130 1045 85 Middle Vaal 50 369 319 Lower Vaal 126 643 517 Mvoti to Umzimkulu 523 798 275 Mzimvubu to Keiskamma 854 374 480 Upper Orange 4447 968 3479 Lower Orange (962) 1028 1990 Fish to Tsitsikamma 418 898 480 Gouritz 275 337 62 Olifants/Doring 335 373 38 Breede 866 633 233 Berg 505 704 199 Overall 13,227 12,871 5126 4770 Author's personal copy 224 J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 Table 4 Future water requirements and available total local yield (including potential for further development) for the year 2025 (DWAF, 2004a). Water management area Total local yield including further development (million m3/a) Low growth scenario (million m3/a) High growth scenario (million m3/a) Limpopo 295 347 379 Luvuvhu/Letaba 405 349 351 Crocodile West and Marico 1084 1438 1898 Olifants 665 1075 1143 Inkomati 1036 914 957 Usutu to Mhlatuze 1124 728 812 Thukela 776 347 420 Upper Vaal 1486 1269 1742 Middle Vaal 67 381 415 Lower Vaal 127 641 703 Mvoti to Umzimkulu 614 1012 1436 Mzimvubu to Keiskamma 886 413 449 Upper Orange 4755 1059 1122 Lower Orange (956) 1079 1102 Fish to Tsitsikamma 452 988 1053 Gouritz 288 353 444 Olifants/Doring 337 370 380 Breede 897 638 704 Berg 602 829 1304 Overall 14,940 14,230 16,814 water meter management, installation of water efficient devices, the planting of water efficient vegetation, promoting retrofitting, communication and education, and the promotion of wastewater reuse (CoCT, 2006). The quality of water needed for some non-drinking applica- tions such as landscape irrigation, toilet and urinal flushing, and a variety of industrial processes, need not be of the same quality required for drinking applications. However in practice in South Africa, drinking water of the highest quality is often used for these non-drinking applications. This practice is unsustainable consid- ering the overview above and hence, wastewater reuse for some non-drinking water requirements presents a promising alternative. In light of the overview of the South African water resources situa- tion presented above and the need for wastewater reuse, this paper is therefore aimed at: (i) providing an overview of wastewater reuse in South Africa and the potential that exists for broader implementation; (ii) highlighting the parameters influencing wastewater reuse based on local attitudes and experiences; and (iii) providing recommendations to facilitate broader implementa- tion of wastewater reuse in South Africa. 2. Wastewater reuse in South Africa Wastewater reuse involves the collection and treatment of wastewater so that it may be used for certain applications. Wastew- ater reuse can form an important component of both wastewater management and water resource management and can offer an environmentally sound option for managing wastewater that dra- matically reduces environmental impacts associated with the discharge of wastewater to surface waters. In addition, reuse can provide an alternative water supply for many activities that do not require drinking water quality and as such, permit the saved drink- ing water to be used elsewhere. Costly projects for drinking water supply may also be delayed due to the reduced demand for drinking as a result of reuse. Lastly, reuse is attractive in many communities because the cost of producing treated wastewater has been found to be lower than the cost of producing drinking water. These reasons form the major drivers for wastewater reuse in many communities across the world. The most significant restraints to reuse include the potential risks to public health, and the potential for reduced sewer or stream flows. If implemented under uncontrolled or unregulated circumstances, treated wastewater can be harmful to living beings (if ingested directly or through irrigated crops) and irrigated soil (due to the chemicals and potential bacteria within the effluent). Reduced sewer flows can result in blocked sewers whilst reduced stream flows can be detrimental to activities extracting certain flow quantities downstream (Ilemobade et al., 2008; IWA, 2008). Wastewater reuse has formed an essential component of water demand management (WDM) in many countries like Jordan, Kuwait, Israel, Spain, Australia, Namibia, Germany, United King- dom, and the United States of America (IWA, 2008). With the broad range of effective wastewater treatment technologies that exist and records of successful wastewater reuse implementation in many of these countries, it has become imperative to evaluate the poten- tial of wastewater reuse as a viable alternative in the drive towards overcoming the challenges of current and future water shortages in South Africa. Although there has been limited uptake of this alterna- tive in many communities within South Africa, a few reuse schemes have been identified. Brief overviews of these schemes are pre- sented below using the categories of reuse published by Dimitriadis (2005) and Mckenzie et al. (2003) i.e. household, district, wide-area urban/agricultural and industrial reuse. 2.1. Household wastewater reuse This category of reuse involves the collection of wastewater which is processed and used for non-drinking requirements within the same building (single- or multiple-dwellings) that generated the wastewater. Examples of this category in South Africa are found in Carnarvon, the Northern Province and Hull Street in Kimberly, the Free State Province: Carnarvon is a village. Before 2005, the management of domestic wastewater (bath, shower and kitchen water) had placed a heavy financial and environmental burden on the municipality and res- idents. At the time, 800 of the households within the community collected and stored their wastewater in containers on a daily basis, as infrastructure for the discarding of wastewater did not exist. Municipal workers then collected this wastewater twice a week using a truck, and dumped the wastewater at the existing WWTWs. Different wastewater recycling systems were then investigated. The preferred system requires residents to convey their household wastewater into a 50 L drum via a filter trap and sump. A sub- mersible pump in the drum kicks in automatically as the sump fills up. The water is then pumped through a hose and sprinkler Author's personal copy J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 225 Guest House Lynedoch primary school The first treatment facility. Max capacity (10 m3/d) The second treatment facility. Max capacity (20 m3/d) Effluent Dam Sustainability Institute offices Control chamber Irrigation (plants, shrubs, trees) Household sewage Sewage Treated effluent for toilet flushing Ultra violet disinfection Storage Boreholes Drinking water supply from municipality Septic tank (1 per 2-3 erven) Treated effluent Residential houses Storage Fig. 2. Schematic of the drinking water and wastewater reuse system within the Lynedoch Eco-village. onto the garden for irrigation. When the sump is almost empty, the pump turns itself off. After the pilot phase, awareness work- shops on operation and maintenance of the wastewater recycling units were conducted with households committing themselves to operating and maintaining the systems (Ilemobade et al., 2008). In Hull Street, Kimberly, each double-storey house is equipped with a dual water reticulation system (a system consisting of sepa- rate pipes that supply drinking and treated wastewater to separate uses). Wastewater from washing machines is channelled using PVC pipes to irrigate lawns above the ground surface whilst wastewater from kitchen sinks is channelled using rock-filled trenches to irri- gate lawns below the surface. Each rock-filled trench contains fat traps, a mulch layer made from gravel, sisal and saw dust, remov- able plastic baskets to catch large particles, and geotextile material (WASE Africa, 2006). The dual systems were implemented in such a manner that each household could easily carry out operation and maintenance tasks. Where regular maintenance was neglected, many of the systems failed. In Carnavon, the indiscriminate use of filtered wastewater poses a threat to especially children and pets that regularly use the irrigated lawns, and may have negative long term environmental consequences due to the accumulation of undesirable chemicals within the irrigated soil. 2.2. District wastewater reuse This category of reuse involves the collection of wastewater at a central location from multiple buildings. The effluent is then pro- cessed and used for non-drinking uses within the same or other buildings. This may include large housing developments. An exam- ple of this category of reuse in South Africa is found in the Lynedoch Eco-village, Western Cape Province. The Lynedoch Eco-village is a pilot sustainability project with ‘zero waste’ as one of its targets. It was founded in 1999 and is managed by a non-profit company, the Lynedoch Development Company (LDC). According to Dowling (2007), the dual water reticulation sys- tem at the Lynedoch Eco-village was designed in response to the following: (i) the scarcity of future water supplies to the Western Cape Province; (ii) the increasing tariffs of drinking water over the next 20 years due to the need to introduce new dams, ground water aquifers or desalination; (iii) the necessity to achieve eco-efficiency through the recy- cling of wastewater. Nutrients present in wastewater are beneficial and can adequately replace chemical fertilizers (Panichsakpatana, 2007). To achieve the objective of wastewater reuse in Lynedoch, two WWTWs were implemented (Fig. 2). The first treatment facility is an engineered micro-ecology con- sisting of a peat filter inoculated with earth worms to deal with the effluent solids within an aerobic environment. This is intended at turning the wastewater into a viable resource (i.e. treated wastew- ater loaded with nitrogen and phosphorus) for irrigation. The second treatment facility (a Vertically Integrated Wetland) pro- duces treated wastewater that is low in nutrients (nitrogen and phosphorus) to be used for household toilet flushing. About 54% savings in drinking water has resulted from wastewater reuse in all the households for the months of April 2006 to January 2007 as is shown in Table 5. Operation and maintenance of the dual system is carried out by employees of the Development Company and this has facili- tated system sustainability. However, overall costs of producing the effluent were about 400% (for the first treatment facility) and 300% (for the second treatment facility) above the drinking water tariff. Hence, although the system may not have been economi- cally viable, it achieved the goals of supplementing drinking water supply (by 54% over 10 months) and promoting eco-efficiency. Author's personal copy 226 J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 Table 5 Drinking water savings due to wastewater reuse in the Lynedoch Eco-village (Dowling, 2007). Month Recycled wastewater (L) Municipal water (L) Total water (L) Drinking water Savings (%) April 2006 42,204 32,361 74,565 57 May 2006 50,445 23,145 73,590 69 June 2006 36,816 97,990 134,806 27 July 2006 76,058 109,619 185,677 41 August 2006 81,655 68,199 149,854 54 September 2006 97,455 63,103 142,558 56 October 2006 54,404 43,996 98,400 55 November 2006–January 2007 376,405 243,114 619,519 61 Total 815,442 681,527 1,496,969 54 Table 6 Formal wastewater reuse within the City of Cape Town (CoCT, 2007). Wastewater treatment works Volume of treated wastewater reused (Ml/d) Reuse activities (%) Sport field/landscape irrigation Industries Agriculture Bellville 4.10 28 71 Kraaifontein 2.10 100 Macassar 2.00 100 Parow 1.50 100 Potsdam 27.60 9 48 43 Scottsdene 0.70 100 Wesfleur (Atlantis) 0.30 100 Total 39.90 Table 7 Informal wastewater reuse within the City of Cape Town (CoCT, 2007). Wastewater treatment works Volume of wastewater reused (Ml/d) Reuse activities (%) Sport field/landscape irrigation Industries Agriculture Athlone 3.00 100 Borcherds Quarry 2.00 100 Cape Flats 4.60 100 Gordonsbay 0.50 100 Kraaifontein 5.50 100 Melkobs Strands 2.00 100 Potsdam 2.40 100 Scottsdene 5.00 100 Total 25.00 2.3. Wide-area urban/agricultural reuse This category of reuse involves the collection of wastewater at a central location from domestic and non-domestic sources within an urban/agricultural area. The effluent is then processed and used for non-drinking requirements at the sources of genera- tion or elsewhere. This category of reuse in South Africa is found in the eThekwini metropolitan authority, the Kwazulu-Natal Province and the CoCT, the Western Cape Province: In the KwaZulu-Natal Province, a Public-Private Partnership exists between the eThekwini Unicity Council and private investors in the production of treated wastewater for industrial applications. The WWTWs is designed to treat 47.5 Ml/d of domestic and indus- trial wastewater with about 74% of the treated wastewater supplied to MONDI Paper.2 The treated wastewater produced meets or exceeds the South African drinking water standards (DWAF, 2004b) in 95% of the parameters measured. Significant benefits of this project have included: • delayed capital investment for increased marine outfall pipeline; 2 Integrated packaging and business paper producing company. • delayed capital investment for future bulk potable water supply infrastructure; • creation of long-term revenue from a levy raised on the produc- tion of recycled water; • reduced cost of water services to Durban’s citizens; and • a 44% reduction in the 2001 water bill for MONDI Paper. In the Western Cape Province, the CoCT stands out as one of the very few local authorities in South Africa that has oper- ated a wastewater reuse system for several decades. Reuse has therefore become a vital component of the city’s integrated water management plan. Treated wastewater is supplied from participat- ing WWTWs to several large scale irrigation and industrial users. Wastewater reuse in the CoCT is grouped as follows: (i) Formal (direct) reusers of wastewater: this group of users are connected to a treated wastewater pipe network of 2527 km from seven WWTWs. The pipe network is funded and operated by the local authority (Table 6). (ii) Private (direct) users of wastewater: these are users who pri- vately fund and operate the treated wastewater pipe networks from the participating WWTWs (e.g. Century City and Steen- berg golf estate from the Cape Flats WWTWs). These schemes withdraw approximately 14.5 Ml/d of treated wastewater. Author's personal copy J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 227 Table 8 Potential for wastewater reuse in the City of Cape Town (CoCT, 2007). Wastewater treatment works Plant capacity (Ml/d) Current reuse (Ml/d) Potential reuse (Ml/d) Total potential reuse (Ml/d) Sport field/landscape irrigation Industry Agriculture Athlone 120.00 3.00 10.68 2.33 0.00 13.00 Bellville 56.00 5.70 9.99 3.99 0.00 13.99 Borcherds Quarry 30.00 2.00 n/a n/a n/a n/a Cape Flats 200.00 4.60 8.62 0.00 0.00 8.62 Gordonsbay 3.50 0.50 1.306 0.00 0.00 1.31 Kraainfontein 18.80 7.60 0.33 0.00 0.00 0.33 Macassar 35.00 2.00 7.56 0.00 0.00 7.56 Melkbos Strands 3.10 2.00 2.00 0.00 0.00 0.00 Mitchells Plain 37.50 0.00 6.06 0.00 0.00 6.06 Parow 1.50 1.50 0.38 0.00 0.00 0.38 Philadelphia 0.08 0.00 0 n/a n/a n/a Potsdam 32.00 30.00 4.35 0.12 15.00 19.47 Scottsdene 7.50 5.70 2.05 0.00 0.00 2.05 Wesfleur (Atlantis) 14.00 0.30 1.56 0.00 0.00 1.56 Wildevoelvlei 14.00 0.00 4.75 0.00 0.00 4.75 Zandvlet 55.00 0.00 4.47 0 0.00 4.47 Total 627.98 64.90 64.12 6.44 15.00 83.55 (iii) Informal (indirect) users of wastewater: a significant number of these users are unregulated and withdraw treated wastewa- ter from downstream points along a surface water source after discharge from the participating WWTWs. These include some golf courses from the Athlone treatment works and agricultural users from Kraaifontein and Scottsdene (Table 7). (iv) Groundwater recharge: in Atlantis, drinking water is supplied primarily from the Atlantis aquifer with extensive recharge occurring using treated domestic wastewater. Two large infil- tration basins, covering an area of approximately 500,000 m2 exist some 500 m upstream of the drinking water extraction point. These basins recharge to the order of about 200 Ml/a (Murray et al., 2007). The CoCT supplies treated wastewater to only large non- domestic consumers. Public safety and costs of retrofitting are the major reasons why domestic consumers are not allowed access to the effluent. Tariffs for treated wastewater in the city are on average, 50% less than drinking water tariffs and hence, financially attractive for large non-drinking water consumers. 2.4. Industrial wastewater reuse This category of reuse involves the on-site collection, process- ing and non-drinking use of wastewater from industrial processes. This category of reuse in South Africa is found in especially mining communities e.g. the Gold Fields gold mine in Driefontein. The Gold Fields gold mine is located at the outskirts of Carletonville, Gauteng province, south west of Johannesburg. It has four WWTWs that pro- duce about 10.36 Ml/d of treated wastewater. 1 Ml/d of this effluent is used for flushing communal toilets at one of the high density res- idences and for landscape irrigation. This practice has existed for a number of years and proven to be successful with no recorded incidents of compromised public health (Ilemobade et al., 2008). 2.5. Potential for wastewater reuse in South Africa The overview of wastewater reuse above shows some valu- able experience of wastewater reuse in South Africa that presents a strong argument for the broader implementation in many arid South African communities. Table 1 also shows that significant quantities of usable return flows from the different water man- agement areas may be exploited for reuse thereby reducing their pollution effects on the existing rivers. For this reason, several studies have been commissioned to investigate the potential for Table 9 Spread of questionnaire respondents. Type of institution Number of questionnaires administered Number of responses Private landscape irrigation (i.e. educational institutions and professional sports clubs) 19 9 Public landscape irrigation 4 2 Crop growing irrigation 1a 1a Petroleum refining 2 1b Pulp and paper manufacturing 3 1 Textile manufacturing 1 0 Construction 2 2 Mining 2 1 Total 34 17 a A group representing about 30 farmers. b The only respondent not located within the CoCT. wastewater reuse in many areas. An extract for a study undertaken for the CoCT is shown in Table 8 (CoCT, 2007). The study concludes that significant opportunities exist within the CoCT for extending current reuse to other large non-domestic consumers of water for non-drinking applications. 3. Parameters influencing the potential for wastewater reuse in the City of Cape Town in Western Cape Province In addition to the survey of existing reuse schemes presented above, a questionnaire was developed and administered to several large users of treated wastewater in order to determine parame- ters which influence the potential for wastewater reuse in South Africa. A significant number of the questionnaires were adminis- tered within the CoCT due to the large number of users located within the City. Sixteen of the seventeen questionnaires returned were from the CoCT (Table 9). Participation in the survey was severely limited by potential respondents who either felt the infor- mation requested was confidential or could be misinterpreted. Twelve of the seventeen respondents reuse wastewater for mainly irrigation. Author's personal copy 228 J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 48% 31% 21% 0% 10% 20% 30% 40% 50% 60% Conserve drinking water and mitigate the effects of water shortages Save money on the water bill Irrigate and improve soil productivity % Fig. 3. Drivers for wastewater reuse amongst respondents. For each of the parameters highlighted below, a brief discussion follows on their influence (positive or negative) on reuse imple- mentation. 3.1. Aridity and growing water demands The South African water resources situation in many areas is characterised by water requirements approaching available yield (Tables 1 and 2). This, as explained earlier, is caused by climatic conditions, which negatively influence freshwater water yields in the face of growing water demands. This situation has therefore stimulated a willingness in many arid areas (e.g. in the Western Cape, Northern Cape and Limpopo provinces) to reuse wastewater. Forty-eight percent of the respondents indicated that the extent of aridity predominantly drove their need to reuse wastewater (Fig. 3). An implication of this is that communities more likely to embrace wastewater reuse are communities in arid areas that typically expe- rience drinking water restrictions, limited access to drinking water, and high drinking water tariffs. 3.2. Distance from source For wide-area urban reuse, the capital costs of laying pipelines to convey treated wastewater from WWTWs to potential users is significant. In the CoCT for instance, as distance from the treated wastewater source increased beyond 500 m, less and less respon- dents were willing to use the resource (Fig. 4)—thus indicating that distance from the WWTWs played a role in large consumers choos- ing to (or not to) reuse wastewater via a wide-area urban reuse system. 3.3. Retrofitting versus new installations In new developments, wide-area urban reuse may be imple- mented from project inception thus lowering installation costs (in comparison to retrofitting)—drinking water pipes would gener- ally be smaller since an integrated design involving drinking and 56% 19% 13% 6% 6% 0% 10% 20% 30% 40% 50% 60% < 500m 500m - 1000m 1000m - 2000m 2000m - 5000m > 5000m % Fig. 4. Distance of wastewater treatment works from respondents. 36% 71% 15% 0% 10% 20% 30% 40% 50% 60% 70% 80% Initial willingness to reuse wastewater Willingness to reuse wastewaterif the tariff is less than drinking water Willingness to reuse wastewater if the tariff is more than drinking water % Fig. 5. Willingness to reuse wastewater based on tariff difference. wastewater pipe networks would be undertaken, costs of installing two pipes in new installations would be cheaper than retrofitting as these costs will be incorporated into the total costs of installing other infrastructure, and the size of the WWTWs would be smaller (Okun, 2007). The high population densities common to many arid South African urban areas is a significant deterrent (due to retrofitting costs) to the implementation of especially wide-area urban reuse schemes. 3.4. Quantity of reuse Primarily supplying large quantity users with treated wastewa- ter can significantly reduce installation and operational costs (due to economies of scale), and to a large extent, guarantee system sus- tainability. Once the large users are supplied, the system may then be extended to smaller quantity users (USEPA and USAID, 1992). This priority scale is similarly adopted by most local authorities involved in wide-area urban reuse with little or no supply of treated wastewater to domestic consumers. Local authorities thus ben- efit from the economies of scale employed in this arrangement and reduce the potential risks to public health (by not supplying domestic consumers). 3.5. Tariffs for drinking water versus treated wastewater Tariffs are generally used as a tool in managing drinking water demand—as tariffs increase, consumers decide whether to use less or pay more, and vice-versa. In the survey, if the tariff for treated wastewater is lower than the tariff for drinking water, 71% of respondents indicated willingness to reuse wastewater (Fig. 5). On the other hand, if the treated wastewater tariff is higher, only 15% of respondents were willing. The difficulty is that often times, the cost of supplying treated wastewater may be within proxim- ity, or substantially higher than the cost for supplying drinking water (such as the Lynedoch Eco-village experience). Reasons for this include expensive wastewater treatment technology and the drinking water tariff excluding one or more items such as (Hassan et al., 1996): (i) the recurrent costs of utilising bulk infrastructure (collection, treatment, storage and distribution); (ii) the marginal costs of new drinking water supplies; Author's personal copy J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 229 (iii) variable tariffs, as opposed to flat rates, to provide for periods of scarcity and peak demands; (iv) the opportunity cost of water; (v) property rights and tradable permit systems in water; and (vi) lifeline tariffs and equity. To be sustainable, tariffs must be inclusive of all costs. Only then will the true differences between drinking water and treated wastewater tariffs be evident. 3.6. Source quality, public health and willingness For treated wastewater to be suitable for the potential reuses without endangering public health (DWAF, 1996), the effluent qual- ity must be as specified in the DWAF (2001) and DWAF (2004b) standards. The quality of treated wastewater is largely deter- mined by the efficiency of the WWTWs and influent qualities. Due to highly toxic influents (especially from industrial sewage) and sub-optimal WWTWs efficiencies, some WWTWs regularly fail to produce wastewater of the prescribed quality. Table 10 depicts the level of compliance to DWAF (2004b) standards in the CoCT (CoCT, 2006). Many inefficient WWTWs in the city have resulted from the historical lack of financial investment due to the high demand on capital throughout the city and this has affected essential maintenance and upgrading (CoCT, 2006). For this rea- son, many respondents undertake further on-site treatment before reuse. Related to the quality of treated wastewater is public health. Protecting public health is achieved by reducing pathogenic micro-organisms, controlling the quantities of different chemi- cal constituents within the treated wastewater, and limiting the public’s exposure (physical contact, inhalation and ingestion) to the treated wastewater. The CoCT only supplies large institutional users with treated wastewater for primarily non-drinking water requirements. This thus reduces the potential risks to public health as domestic consumers are not connected to the treated wastewa- ter pipe networks. Public exposure to the wastewater directly influences willing- ness to reuse (Friedler et al., 2006)—where physical contact is likely, willingness to reuse is generally low. Willingness to reuse wastew- ater has determined the success of many reuse projects with some schemes failing because decision-makers underestimated the need to engage the benefitting community (Okun, 2002; Po et al., 2004). Willingness to reuse is also influenced by political will and the perceptions of risk associated with reuse. In the survey, 88% of Table 10 Wastewater treatment works in the City of Cape Town (CoCT, 2006). Treatment works Level of compliance to standards (DWAF, 2004b) (%) Athlone 83.00 Bellville 76.70 Borcherds Quarry 97.45 Cape Flats 66.67 Gordonsbay 96.70 Kraainfontein 86.75 Llandudno 83.00 Macassar 85.50 Melkbosstrand 99.40 Miller’s Point 77.00 Mitchells Plain 93.00 Oudekraal 87.90 Parow 88.00 Potsdam 52.50 Scottsdene 93.35 Simon’s Town 58.80 Wesfleur (Atlantis) 99.51 Wildevoelvlei 96.50 Zandvliet 97.00 respondents perceived the risks associated with wastewater reuse to be low. This perception thus encouraged reuse amongst respon- dents. 3.7. Public trust in the service provider and knowledge of reuse Service providers of drinking water are continually faced with the challenges pertaining to uninterrupted drinking water supply. Interruptions encourage apathy and negate consumers’ trust in a service provider’s ability to provide reliable service irrespective of whether it is drinking water supply or treated wastewater. Per- ception surveys conducted by Po et al. (2004) showed that trust in the Water Corporation of Western Australia to provide safe and reliable treated wastewater was critical to why residents were will- ing to reuse wastewater. Respondents’ trust in the service provider to supply the appropriate quality of treated wastewater was 48%. This response is poor and likely influenced by the poor qualities of treated wastewater that have been supplied these respondents over time prompting further on-site treatment of the effluent. Closely related to trust is knowledge of reuse. The more knowl- edgeable potential users are, the better empowered they are in deciding to (or not to) embrace reuse. Knowledge involves an awareness of local drinking water supply problems and the poten- tial for treated wastewater to satisfy some water requirements, an understanding of the quality of treated wastewater that can be pro- duced using the available technology, and an assurance that the treated wastewater system will involve minimal risk to the public. When potential consumers are educated about reuse, the decision to (or not to) embrace reuse is usually clearly articulated. 3.8. Regulations and guidelines for reuse National regulations that briefly address reuse can be found in the documents below: (i) the latest revision of the Water Services Act of 1997 relating to greywater and treated wastewater (DWAF, 2001); and (ii) the latest revision of the National Water Act of 1998, 37(1) relat- ing to irrigation of any land with waste or water containing waste generated through any industrial activity or by a water works (DWAF, 2004b). In these documents, there is no objection to the reuse of wastew- ater for different non-drinking water requirements. However, reuse must be permitted and monitored by the relevant Water Services Authority using rigorously developed By-Laws. The CoCT appears to be the only local government authority in South Africa with detailed By-Laws for wastewater reuse within the city (CoCT, 2007). There are no current national guidelines on wastewater reuse in South Africa. The existing guideline—the South African guide for the permissible utilisation and disposal of treated effluent (DNHPD, 1978), is currently 30 years-old and promotes the concept of ‘No potential risk’ to public health when reusing wastewater. For this guideline to be employed, expensive technology and processes are often required. This therefore makes the DNHPD (Ibid) guide- line unaffordable when implementing wastewater reuse in typical South African developing communities. 4. Recommendations To facilitate broader implementation of wastewater reuse, the recommendations below are proffered: (i) there is urgent need for the DWAF to develop a national guide- line document that presents a consistent technical guide for Author's personal copy 230 J.R. Adewumi et al. / Resources, Conservation and Recycling 55 (2010) 221–231 the implementation of wastewater reuse and reuse systems. The DNHPD (1978) guideline is outdated but may, with the CoCT By-Laws (CoCT, 2006), provide some input into the new guideline. The proposed guideline should include wastew- ater quality criteria for different non-drinking applications, uniquely designed and standardised engineering materials (e.g. pipes, meter boxes, valves, taps and tanks) and specifi- cations (e.g. sizes, thickness, colour, labelling) for wastewater reuse systems (unique features of a reuse system would be valuable in preventing cross-connections with drinking net- works); (ii) in order to ensure the economic feasibility of wastewater reuse, a careful life cycle cost-benefit analysis needs to be carried out within the context of other water resource alterna- tives and a full appreciation of the true costs of drinking water supply provision. There are potentially large savings that may be realised in avoiding treating water to drinking standards for non-drinking uses; (iii) tariffs have been shown to significantly influence potential consumers’ willingness to embrace wastewater reuse. Incen- tives to achieve wastewater tariffs lower than drinking water tariffs may include subsidies to consumers for wastewater reuse, utilisation of existing infrastructure (e.g. WWTWs), and/or the installation of a reuse system during the construc- tion of new buildings; (iv) to guarantee a high level of service for wastewater reuse, a program of regular control and monitoring of influent from various sources (especially industries) should be implemented by local authorities. In addition, many local authorities need to be equipped with qualified personnel that will undertake con- trol and monitoring tasks and enforce By-Laws. Wastewater reuse must not be implemented where the qualified institu- tional capacity is deficient; (v) willingness to reuse by potential users is critical prior to implementation. Decision-makers must also understand the conditions under which potential users will be willing to reuse wastewater. From the study, it was clear that non-drinking water requirements that involved minimal human contact (e.g. landscape irrigation) were preferred. Hence, it would be wise for decision-makers to target these uses when reuse is to be implemented; (vi) if wide-area urban systems are to be implemented, local authorities must first consistently perform well in the ser- vices rendered to communities. This will increase consumers’ trust in the local authority’s ability to implement reuse sys- tems and therefore reduce any potential risks to public health and safety. It is fruitless for local authorities to consider imple- menting wastewater reuse when existing service levels are low; and (vii) the general awareness of decision-makers, builders, plumbers, product manufacturers, architects, etc. to the potential of wastewater reuse will be beneficial for a better understand- ing and broader implementation of wastewater reuse. Also, an integrated water reuse education/awareness programme would be beneficial for potential consumers to understand wastewater reuse. This programme can be enhanced using case studies of wastewater reuse in other communities. 5. Conclusion South Africa is a semi-arid country with many communities struggling to access reliable and adequate quantities of water for diverse water requirements. Wastewater reuse for non-drinking water requirements has been, for many years, a promising option for supplementing municipal water supply despite the limited implementation in many parts of the country. With increasing demands on existing freshwater resources and pressures on exist- ing municipal supplies, the need to implement wastewater reuse has increased. This paper therefore presents an overview of the South African water resources situation in order to put the need for wastewater reuse into perspective, an overview of wastewater reuse and the potential for broader implementation, a discus- sion on the parameters influencing wastewater reuse based on local attitudes and experience, and recommendations to facili- tate broader implementation of wastewater reuse in South Africa. Significant potential exists for implementing wastewater reuse for large non-drinking applications (e.g. landscape irrigation and industrial processes) and arid areas of South Africa especially pro- vide ample opportunities for implementation of reuse. Parameters highlighted to influence broader implementation of reuse in addi- tion to aridity include distance from source, retrofitting versus new installations, quantity of reuse, pricing, source quality, pub- lic health, willingness, public trust and knowledge, and regulations and guidelines for reuse. It is therefore recommended that these parameters be considered prior to implementation. Acknowledgement Funding from the South African Water Research Commission (Project K5/1701) is gratefully acknowledged. References CoCT, City of Cape Town. Water services development plan for City of Cape Town 2006/07; May 2006. CoCT, City of Cape Town. Treated effluent re-uses strategy and master plan- ning within the City of Cape Town. BVi Consulting Engineers. BVi Report No. C1500/1.1; April 2007. Dimitriadis S. Issues encountered in advancing Australia’s water recycling schemes. Research Brief, Parliamentary Library, Parliament of Australia, Department of Parliamentary Services. No. 2. 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