Restructuration du secteur de l’eau Potable en Afrique Central et de l’ouest francophone
Le présent article nous présente les résultats sur la restructuration du secteur de l’eau potable en Afrique Centrale et de l’Ouest Francophone. Il montre l’état des lieux, les défis et propose des solutions sur la restructurations du secteur de l’eau potable en Afrique Centrale et de l’Ouest Francophone
l’article présente les résultats des travaux de recherches dans le secteur du wash de trois jeunes africains à savoir : KOTIE SIDIBE de nationalité Malienne diplômée d’un Master 2 en géomatique, aménagement, gestion des territoires de l’Université des Sciences Sociales et de Gestion de Bamako ; FOUTAMATA MALEBA COULIBALY de nationalité Malienne Etudiante en master Génie Environmental à L’ Eni/ABT de bamako(Mali) et CHARLES TAPALNA de nationalité Nigériane es Master en études stratégiques de l’Université de Maiduguri
L’objectif était d’analyser les différentes solutions et innovations dans le secteur du wash au Mali et au Nigéria. L’approche méthodologique utilisée par les trois chercheurs dans le secteur du wash nous présente les différents modes de collecte des données directe (enquête de terrain, documentation physique) et collecte indirecte (recherche documentaire en ligne). Les résultats de ses travaux se présentent comme suite :
_ s’agissant des travaux de recherche de KOTIE SIDIBE qui sont intitulés :« APPORT DU SIG DANS LA GESTION DES DECHETS D’EQUIPEMENTS ELECTRIQUES ET ELECTRONIQUES DANS LA COMMUNE VI DU DISTRICT DE BAMAKO »
Au total, 274 sites ont été géolocalisés dans les onze (11) quartiers de la commune VI : Banankabougou (36), Dianéguéla (18), Faladié (32), Magnambougou (34), Missabougou (14), Yirimadio (42), Sokorodji (18), Sogoniko (25), Niamakoro (23), Sénou (23), Zone aéroportuaire (9)
Comme solution technologique innovante, elle propose un système d’informations géographique (SIG), un excellent outil pour assurer le suivi de tous les acteurs, les trajets de distributions, la fréquence des grossisses, et d’autre part, une planification du traitement (organisation des acteurs de traitement existante, réalisation de nouveaux emplacements pour les acteurs). Elle propose aussi la mise sur pied, des textes législatifs régulant le domaine de la gestion des déchets électriques au Mali
Les contrats de concession (SOMAPEP-SA) et d’affermage (SOMAGEP-SA) du réseau de distribution de Bamako devrait être 81%, mais il se situe aux environs de 63% soit 18 points d’écart. Ce qui entraine de nombreuses pertes pour la SOMAGEP-SA. Comme solutions, elle propose la modernisation des systèmes de mesures (compteurs plus précis et télé relevables)
Comme solutions innovantes aux défis rencontrées par les femmes dans les pratiques actuelles au Nigéria en matière d’eau et d’assainissement, d’hygiène, et d’assainissement nous avons la fourniture de pompes à eau fonctionnant à l’énergie solaire, d’unités mobiles de purification de l’eau, promotion de l’hygiène au niveau communautaire, fourniture de kits WASH d’urgence et formation/renforcement des capacités
l’article permettra de renforcer les capacités des jeunes chercheurs et innovateurs dans le domaine de l’eau, de l’assainissement et de l’hygiène en Afrique
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The article presents the results of the research work in the wash sector of three young Africans, namely: KOTIE SIDIBE of Malian nationality with a Master 2 in geomatics, planning, land management from the University of Social Sciences and Management of Bamako; FOUTAMATA MALEBA COULIBALY of Malian nationality Student in Environmental Engineering at Eni/ABT of Bamako (Mali) and CHARLES TAPALNA of Nigerian nationality is Master in Strategic Studies from the University of Maiduguri
The objective was to analyze the different solutions and innovations in the wash sector in Mali and Nigeria. The methodological approach used by the three researchers in the wash sector presents the different modes of direct data collection (field survey, physical documentation) and indirect collection (online documentary research). The results of his work are as follows:
_ Regarding the research work of KOTIE SIDIBE which is entitled: “CONTRIBUTION OF GIS IN THE MANAGEMENT OF WASTE ELECTRICAL AND ELECTRONIC EQUIPMENT IN COMMUNE VI OF THE DISTRICT OF BAMAKO”
A total of 274 sites have been geolocated in the eleven (11) districts of Commune VI: Banankabougou (36), Dianéguéla (18), Faladié (32), Magnambougou (34), Missabougou (14), Yirimadio (42), Sokorodji (18), Sogoniko (25), Niamakoro (23), Sénou (23), Airport Zone (9)
As an innovative technological solution, it offers a geographic information system (GIS), an excellent tool to monitor all the actors, distribution routes, the frequency of grow-ups, and on the other hand, a treatment planning (organization of existing treatment actors, creation of new locations for the actors). It also proposes the establishment of legislative texts regulating the field of electrical waste management in Mali
– Regarding the research work of FOUTAMATA MALEBA COULIBALY with the title: “APPROACH TO THE REDUCTION OF NON-REVENUE WATER IN WATER COMPANIES (SOMAPEP/SOMAGEP (Bamako)”
The concession (SOMAPEP-SA) and leasing (SOMAGEP-SA) contracts for the Bamako distribution network should be 81%, but it is around 63%, i.e. 18 points difference. This leads to many losses for SOMAGEP-SA. As solutions, it proposes the modernization of measurement systems (more accurate meters and remotely readable meters)
– Regarding the CHARLES TAPALNA research work, the title is: “ASSESSING THE IMPACT OF WOMEN’S PARTICIPATION IN THE WATER, SANITATION AND HYGIENE COMMITTEE ON SUSTAINABLE WASHING SERVICES AND IMPLEMENTING BEST PRACTICES IN MAIDUGURI, NIGERIA”
As innovative solutions to the challenges faced by women in current practices in Nigeria in terms of water and sanitation, hygiene, and sanitation we have the provision of solar-powered water pumps, mobile water purification units, hygiene promotion at the community level, provision of emergency WASH kits and training/capacity building
This article will build the capacity of young researchers and innovators in the field of water, sanitation and hygiene in Africa.
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Non-judicious and long-term application of chemical fertilizers not only deteriorate soil quality but also contributes to climate change effects due to the emission of greenhouse gases during the production and application of these fertilizers. On the other hand, there is an urgent need to look for alternative nutrient sources for food production to feed the growing population.
It is widely known that human excreta is rich in nutrients, specifically Nitrogen and Phosphorous. With the recent thrust on faecal sludge treatment and safely managed sanitation, there is an opportunity to use human excreta as a nutrient source. However, there are concerns of health risks due to the presence of pathogens in faeces. The main cause of concern is the soil-transmitted helminth infections as these are highly resistant to treatment and viable for several years.
In this context, this study was conducted in 4 locations (FSTPs – Faecal sludge treatment plants) of India – Angul, Dhenkanal, Karunguzhi and Devanahalli with the main objective to evaluate the efficiency of polycarbonate-based greenhouse solar dryers in reducing the Helminths eggs in the final treated sludges. Greenhouse solar dryers (GHSD) use passive drying to help increase the temperature and decrease humidity to ensure pathogen kill as well as faster drying.
Following were the assumptions made for the study,
GHSD is the polycarbonate sheet installed over the drying beds. This has a parabolic shape to resist wind and to induce greenhouse effect inside the drier. This greenhouse effect inside the drying chamber helps removing the moisture laden air and the moisture content from the drying product (Figure 2).
Solar pasteurisation unit (SPU) follows the same working principle and the structure of the GHSD. However, the height of the roof is less compared to the GHSD. The dried sludge from the GHSD is placed in the SPU. Due to reduced height of the chamber and low moisture content of the sludge, SPU can reach to a higher temperature of more than 60 degrees Celsius which will help eliminating the pathogens (Figure 3).
Galvanised (GI) sheet is one of the most used roofing materials over the sludge drying beds. These are galvanized metals made of thin sheets, coated with zinc. The main purpose of these sheets is to protect the drying beds from getting wet during rainy season.
Below mentioned scenarios were studied under the project,
‘Multiple-use services’ (MUS) takes into account the fact that households use water for both domestic and for productive uses. This paper is the first to determine how managed aquifer recharge (MAR) systems are a form of MUS. Two cases were studied in India and in Kenya. In the Kenyan case, sand dams are the form of MAR, and in India check dams and infiltration ponds of various scales are used. Through observations, interviews, and water quality data, it is possible to describe how the communities access the water from these infrastructures in multiple ways for different uses, according to their water needs and the characteristics of the different access points. MAR involves harvesting rainwater and retaining run-off water into the dry season thus increasing the amount of available water and enabling diversification of water uses. It should therefore be considered as an option by water managers aiming to develop water resources meeting both the domestic and productive needs of communities.
The city of Nairobi in Kenya has a population of about 5 million people within the city itself, but the population is estimated to be about 10.8 million within the metropolitan area. The city is grappling with the issue of water, as the current production is about 500 000m3/day, against a demand of 800,000m3/day. Heavy infrastructure and capital are required to be able to bridge this Gap. A strategy that would help in reducing this gap would be most welcome. Sewerage coverage is estimated at about 50%, leaving about 50% to depend on on-site sanitation like septic tank and using exhausters and pit latrines in extreme cases. A method that would enable to bring up a decentralized wastewater treatment plant that do not require heavy infrastructure like sewer networks is most welcome.
The city also has great challenges in the collection of wastewater and fecal sludge because of the fast-growing population due to rural-urban migration, which has accelerated the population growth. Rivers in the city are heavily polluted because of the overflow from the current sewer networks and the discharges from areas like focus settlement that are not connected. The open channel that was visible at Uhuru Park was initially meant to convey storm water but is currently used to conveying storm water melt with sewage from the overflow from diverse areas and institutions.
Currency in Nairobi, the most common wastewater treatment systems are stabilization ponds and aerated lagoon coupled with constructed wetlands as well as conventional treatment systems. But the main problem is that this requires huge infrastructure for collection of sewage and transporting it to a central point. So, the need for decentralized systems is key.
The photo on Page 4 (See attachment) is one of the rivers in Nairobi which is flowing next to an informal settlement; this picture presents the heavy pollution in the river and the environment. This has surely helped the Government to come up with the Nairobi River Rehabilitation Commission to try and clean up these rivers so that the water can be available for other uses. The system being discussed actually falls into that category of helping to clean the rivers. The initiative to have this decentralized system in Uhuru Park was initiated at a very high level, when the President of Estonia visited Kenya, and had discussions with her host President of Kenya on areas of bilateral cooperation. One of the results was that Estonia being fairly advanced in terms of technologies, especially in water and wastewater treatment, could assist Kenya in coming up with very innovative ways of treating wastewater, and that is how the Spacedrip device was booted. The Estonia President nominated the Spacedrip team which was accompanying her to do a pilot in Nairobi, and the Kenyan Government nominated the Nairobi Metropolitan services and the Executive Office of the President to work on the pilot. It was deemed appropriate to pilot this system in a very central place, where it can be accessed by other leaders and institutions from around the country. And that’s how the pilot was positioned in Uhuru Park (See Attachment, Photo in Page 7), one of the main recreation parks located within the Central Business District (CBD) in Nairobi. Anybody coming for recreation within the park can see it. The map (See attachment, Page 6) presents in light green the Uhuru Park, which is a very centrally placed within Nairobi CBD with the major governmental institutions located in close proximity including even the Parliament, the President’s Office, the city hall, major hotels and other business premises.
Uhuru Park was chosen for this pilot because before the installation of this system, potable water was used to irrigate the Park, which is a huge area of over 50ha, with the corresponding pressure on potable water. Indeed, the city is already experiencing a deficit of 300 000, and instead of saving on the water, the same water is used for irrigating the park. So, the idea of putting this system in the Uhuru Park was to make sure that the effluent treated from the system would be used to irrigate the park, and by so doing help in reducing the pressure on demand on the drinking water.
Aqua Consult Baltic designed the technology enabling to connect with the irrigation infrastructure of the Uhuru Park, and there has been a partnership on the consultation during the commissioning and six-months operation of the plant handed over to Nairobi Water Sewage Corporation (NSWC). Ruji Africa was the local partner of Spacedrip helping in the preparation, installation and piloting the automated wastewater treatment and reuse system. We have already obtained an update on environmental impact assessment from a Regulator, which is the National Environment Management Authority.
One of the key benefits of this water reuse system is that it requires a very small space, and the container system can be installed inside a building or smaller areas, unlike the other systems which require huge plots of land (land in a city like Nairobi is very scarce to get). This is therefore a solution to areas that do not have land. The efficiency of the system lies in the total pathogenic removal for key area, because the effluent can then be used for other uses like irrigation. In the future, effluents from this system could also be used in flushing of toilets and cleaning as the case maybe, since most of the water is used for cleaning services. For now, because of the stigma associated with the sewage water, it might be too early to start talking about using it for drinking. It already helps to reduce pressure on drinking water, and it is estimated that adopting this water reuse technology in most of the heavy consumers of water (like tourism, hospitality industries, informal settlements, commercial and residential buildings, food processing…) could help cut the demand for water by about 50%, and then the pressure on potable water could really come down.
One key input of this system is electricity because of both the automation and the pumping within the system. However, this can be addressed in future. Currently, the system also incorporates a partner’s solar system that produces part of the electricity, especially for automation and critical operations of the system. But in future, we think the solar energy should be made the main source of energy by incorporating more solar panels and batteries to store the energy.
Financially, this system gives an advantage, especially saving on heavy cost for the construction of the infrastructure required for centralizing the system. This is the main cost that applies for the sewerage system. With a decentralized technology and no need for heavy infrastructure, specific saving in the cost makes this system a big advantage.
The result of this piloting is supposed to inform and advise the policy makers and help them in the development of by-laws that would be required for some institutions. With the water consumption and discharge of given capacity, it should be of interest to install this water treatment and reuse system in the tourism and the hospitality industry, urban, commercial, building institutions, and the food processing industries. Doing so will also help the private sector participation accelerating the coverage in terms of sewerage and help those involved in the management and control of water demands. So, as an addition to constructing new infrastructure to bring in more water, we can manage the quantity we have better by treating our effluent and reusing it. This is already happening in buildings like the local university of Nairobi, which is harvesting all the water within the building that is then reused in flushing of toilets. This idea is not very far-fetched, and its time has come. Policy-makers need to be advised on that so as to come up with necessary bylaws to help manage the water demand distribution in the country.
Aqua Consult Baltic was established in 1997 in Estonia, and the technology presented herein came into existence in Kenya thanks to a local company. This mother company located in Germany in Hanover, grew up from there. She implements projects around the world and mainly in Baltic States. This is an engineering and consulting company which mostly specializes on wastewater treatment and derivatives, secondary waste handling and municipal waste treatment plant. The company is currently working on a Slovenia and Vienna Project, which is 550 000PE and also in Tallinn, Estonia for 400 000 equivalents. Given that industrial municipal waste is difficult to predict, it is important to know its boundaries and behavior; so, for this type of waste, there is need to do a lot of modeling which includes fractionation of the wastewater and doing the piloting before providing the engineered solution to the customer. The company deals with oil and gas industry, chemical foods, agriculture, industrial plant, and projects linked to water reuse systems. Currently, the Tallinn water treatment of 400,000 equivalents transforms the surface water into potable water, using new technologies that are developed. The company has built good relations with universities, where testing and research are carried out.
Besides, Spacedrip – also an Estonian company – is an innovative and young company that focuses on water treatment systems which reuse water in a small scale of 25 to top 2000 people for water companies, real estate developers and defense sector. The defense sector for example has mobile units in different places that need to be supplied with water. Spacedrip thus provides them with showering or toilet systems that reuse water continuously.
Relationship between Aqua Consult Baltic and Spacedrip Group
A few years ago, Aqua Consult informed Spacedrip of the design of a new model of houses prefabricated in the factory and deployed to the sites. However, there is occasionally no infrastructure on the site, neither a wastewater nor a drinking water system. They needed a machine which was able to transform wastewater into drinking water. Spacedrip made the design, which is now used in Aqua Consult Baltic factory and the latter developed it further to what it has become today. It is now a more reliable product that can be fully put on automation, a very nice product. This device was funded by the Government of Estonia as a technology to be exported in other countries, and whose added value is the environment-friendly feature and saving the greenhouse potential.
During the funding, the Estonia President at that time visited Kenya. He knew about the existence of this company making wastewater into drinking water; indeed, there is less than 1 million people or so in Estonia, and everybody know each other. He told his peer, the President of Kenya of this technology, and the latter showed interested, hence the relationship with partners on site and the launch of this Kenya project.
Problem Statement
As President William Ruto put it: “Kenya Government has resolved to not only reclaim Nairobi’s reputation as Africa’s green city but also live up to its ancestral identity as the river of cool and fresh water”. The Kenya project emerged from findings below:
A pilot plant was thus installed at Uhuru Park, Nairobi for two purposes:
The Solution Implemented
The Spacedrip device (see page 7 in attachment) is a container treatment plant that takes up the wastewater from a channel that flows through the Uhuru Park, Nairobi up to 50 m3/day and cleans it up so it can be reused for irrigation of the park. The system is handled with an automation software so it can be monitored and run up from a far distance and keeps a working order in every cases. This technology is not new per say, but it has a sedimentation tank in front of it. There is a biological part where organics and a bit of nitrogen are removed; then, a filtration unit that micro- filtrates out most of the bacteria; clean water enters a tank in a technical chamber and from there, it is filtrated by UV light and chlorine when necessary. So, water comes into the treatment plant from the stormwater drain channel and goes out the treatment plant through sprinklers in the park. Water arrives through a storm water channel. There are quite no rainy events there, but a lot of water coming from septic tanks and industrial site discharge, which is unknown and difficult to predict. This means that water flowing through is quite dirty, and direct use for the irrigation is not a good idea. However, following treatment, it becomes very clean from organics and bacteria. This technology has been used at the Uhuru Park for two weeks now.
Results Obtained
The commissioning went well a month ago (May 2023), and the system has been running in its full capacity for two weeks now. Currently, up to 25% of the necessary Uhuru Park irrigation water is coming from this treated wastewater device. The implementation of this device aimed to give a proof that this kind of system with sound automated plug and play technology works well. These compact units can be placed anywhere, even in small areas. It can run for a long period of time and is in a testing phase. The input and outputs analyze results are presented in Chart 2 (See Page 9 in attachment), with a 100% bacterial removal thanks to this technology. The influent and output picture shows the water obtained is quite pure. However, it is not safe enough to be consumed and is only for irrigation purposes.
Conclusion
This kind of system is same with Seehausen (Germany) water reuse systems. But this is a smaller unit that is quite compact, and which can be placed in small areas or bigger city centers where the wastewater is reduced. The water obtained can be used for toilet flushing or garden irrigation and there is no need for building new infrastructure to use it. Thanks to the IT Solution enabling the distance monitoring, there is no need to go on site for maintenance.
Therefore, it is possible to predict the maintenance of the system, that will allow it to run for a long time and avoid breakdowns. Pictures of some small three-meters containers are presented in Page 10 (See attachment); these are devices with showering and toilet units that were produced by Spacedrip for military projects, and which can be placed anywhere for continuous reuse of water.
During the 6th edition of Ask The Experts series themed: “Valorising the end-products of domestic and industrial wastewater treatment” organized on April 25th, 2023, by the African Water and Sanitation Association (AfWASA) with the German- African Partnership for Water & Sanitation (GAPWAS), the collaboration between the cities of Windhoek in Namibia and Bremen in Germany was highlighted.
Indeed, Windhoek and Bremen cities began a collaboration in year 2000 from a long historical relationship including the support from Namibia struggle for independence. In 2013, the two partners joined the municipal climate partnership project, continuing the tradition of knowledge sharing. The project mainly prioritized the solid waste management, wastewater management and provision of basic sanitation services for informal settlements in a quest to contribute to the United Nations Sustainable Development Goals. The city of Windhoek and Seehausen started collaborating in 2018. This knowledge- based collaboration focused on issues mainly pertaining to wastewater treatment. The team usually meets on a monthly basis to discuss and analyze different topics, seeking for solutions and improvements.
The collaboration approach over the past couple of years focused on exchangeable visits in Nambia and Bremen on topics of common interest. For example, the two charts on variation in influent flowrate (see Attachment, Page 3) show the hourly influent volumes of Seehausen and Gammams plants, and the hourly organic meta concentrations. For both plants, the factor between the minimum and maximum daily figures is about 0.5. But there are some differences between the trends or the hourly patterns per day, which could be due to the travel time of water to the plant, which can differ. In Bremen, there is also a storage capacity on the pipelines. The patterns could also be different per hour of a day due to industrial and domestic waste. Indeed, Gammams in Whindhoek only takes water of domestic origin, while Bremen takes wastewater from domestic and industrial origin, considering that industrial waste is very hard to predict. Also, in Namibia there is only a separate sewer system, meaning that most of the infiltration is diverted into rivers, while Seehausen in Bremen has both the combined and a separate sewer. These are all important factors, among others that can be used to troubleshoot or rectify faults towards improvement and to plan optimization to ensure process efficiency.
This gives few insights into the actual cooperation which aim to get more knowledge on the whereabout of our carbon and what it can be used for. In one of the Bremen treatment plant balances (see Attachment, Page 4), we can see the quantity of carbon which is transferred to the Bio reactor, and the quantity which is brought to the digestion. Biogas is derived from that, and with a combined heat and the power plant from which energy can be produced. So, every optimization of a treatment plant, can change the future. The results at the end of the treatment process should be the possibility to produce more energy and gas, or the use of carbon for denitrification to get a better affluent quality of treatment plant. Exchanges with laboratories that make the analyzes and other partners of the wastewater sector revolves around similarities in operations and special tasks as well to identify what can learned from each other. For example, Windhoek has a 50 years’ experience in removal of micropollutants and climate change adaptation. Bremen can learn this know-how from Windhoek, especially since Bremen is getting more and more dry; natural water bodies get increasingly smaller, and the city has to think over how to use water and what for. For example, Bremen uses semi-purified water for gardens or public places just like Windhoek. On another realm, Bremen has been preparing for rainfall events for the last 30 years, and this is something Windhoek may learn from Bremen.
Bremen’s biggest wastewater treatment plant is Seehausen, and there is a process to get an energy neutral plant. Bremen is a city in the northern part of Germany, and the responsible for city sanitation is hanseWasser, operating on a public- private partnership model. The Bremen area is very flat; consequently, more than 200 pumping stations are needed to pump every drop of wastewater against gravity to the treatment plant in Bremen Seehausen located in the highest (1012 meters higher than the rest) region of the city.
The treatment plant in Seehausen had about 1 million inhabitants connected, and the wastewater treatment plant in the northern part of Bremen had about 160,000 inhabitants connected. The presentation (see Attachment, Page 8) highlights a very good development of the self-production of energy, with two (2) big steps between 2010, 2011 and in 2013. The first step was the introduction of a new wind turbine, and in 2013, the combined heat and power plant station was renewed; this allowed the generation of more energy from the gas available. In 2022, the self-production stood at 130%, with about 100% from the combined heat and power plants and 28% from wind turbines. It rains very often at Bremen, and the city can only generate around 1 to 2% of energy from self-production. The city didn’t only focus on the production, but also on reduction of the total energy consumption of the plant, with a drop of about 25% over the years with optimization and a new aggregate.
The specific energy consumption per inhabitant is also an indicator for the reduction. Bremen’s way to energy neutrality is based on three pillars:
The presentation (see Attachment, Page 12) showcases parts of set rules, with specific energy consumption of the whole treatment plant. The total energy demand of the plant is known, as well as the number of inhabitants connected to the plant; this allows to calculate the specific energy demand in kw/hours per inhabitant and per year; getting inside the benchmarking system of this set of rules allows to find the frequency of lower deviation and understand the self-monitoring system of energy of a plant. The presentation (see Attachment, Page 13) also highlights the results of energy analyzers from the plant, with the best values that the plant can reach over the year. Bremen-Fargo is a bit far away from this added value and must figure out how to make the treatment plant better in energy consumption.
To sum up, the project started at a good point because of lot of aggregates for energy production, and high demand of energy had to be renewed. A company-wide goal was set to get energy neutral for the whole company; this allowed to reduce the specific demand of aggregates and raised the production efficiency.
As part of the 6th edition of Ask The Experts series themed: “Valorising the end-products of domestic and industrial wastewater treatment” organized on April 25th, 2023, by the African Water and Sanitation Association (AfWASA) in collaboration with the German- African Partnership for Water & Sanitation (GAPWAS), Justina Haihambo, Process Engineer Gammams Wastewater care Works at the City of Windhoek, central area of Namibia gave an insight into Windhoek’s direct potable reclamation.
Windhoek is located in Namibia, the driest country of sub-Saharan Africa, and is also the hub for the country’s economic, industrial, academic, commercial and political activities. The mission of the City of Windhoek is to enhance the quality of life of the population through efficient and effective municipal services and to improve water security. In the last housing and population census, the population of Windhoek was forecasted at 341000 people, but currently at a growth rate of 4.3%, is forecasted at about 441700 people. The annual water consumption of Windhoek is 27 000 000 m3/year, with an annual increase of about 3%. This, coupled with factors below, make the provision of water security of Windhoek uncertain:
The timeline of the potable water supply scheme of Windhoek has to be understood and considered in other to aid in understanding how wastewater is or has become a valuable resource toward water security. So, Windhoek was settled in 1840 partly because of the availability of groundwater from permanent hot springs. Until 1960, the city continued to heavily rely on groundwater from a well field for its water supply security, despite the construction of two small state-owned dams build-in ephemeral rivers in 1993 and 1958 respectively. So, meanwhile the population continued to rapidly increase, the city continued to experience regular drought in parallel. Consequently, all water resources at the time became depleted, which made the future of water security uncertain. Heavily relying on too small construction dams in ephemeral rivers and groundwater for water supply led to the fact that in terms of water, Windhoek became vulnerable; thus cementing the idea of unconditional water sources and supply and the idea of direct potable reclamation as well. This led to the construction of a direct potable reclamation plant in 1968 to argument the groundwater and the surface water supply, which at the time had become uncertain and unreliable. So, from 1970 to 1982, the state-owned supply system got extended in a three-dams systems.
From 1990 to present, Windhoek has been relying on what is known as the central area of Namibia supply scheme for its water supply or its potable supply needs. This supply scheme consists of the following:
This direct potable reclamation was constructed at an initial capacity of about 4.8mega liters a day, which got increased over time. But at the end of its lifespan, in the midst of severe drought in 1997 and with lack of a sustainable water supply option at the time, it was decided to build a bigger plant at a capacity of 21 mega liters a day. Another Windhoek sustainable options to reduce the water demand, was the establishment of a semi- purified and irrigation supply scheme. This was established in 1993, with the construction of a dwell pipeline system to convey water from the old direct potable reclamation plant to sports fields of schools and establishment of businesses. This semi- purified water is also used at municipal wastewater purification plant for irrigation and general cleaning of equipment. This irrigation water supply scheme was established to decrease the Windhoek water demand by about 8%.
In another view, the current potable water supply scheme consists of:
Water reclamation or water reuse is known in theory as one of the main alternatives to reduce water demand. Therefore, Chart 1 in the presentation attached shows the annual consumption of water demand by source for Windhoek for the past 55 years. So, in general, the introduction of the direct potable reclamation means that the volume of water required from other conventional sources is reduced, and especially with introduction of the irrigation supply scheme in 1993. Direct potable reclamation also means that in normal metrological conditions, the groundwater can be preserved for use sustainably when necessary; for example, as was the case during the 2013 to 2019 drought, and more notable in 2019 when Windhoek experienced “the worst drought in 90 years” with the lowest average rainfall recorded.
Over the years or the 55 years, the water demand kept increasing proportionally with the growth rate; however, there were some notable reductions in water demands, and the weight of droughts in 1982-1983, 1996-1997, 2013-2019 were mostly attributed to water demand management.
Importantly, the ongoing success of direct potable reclamation can be attributed to correct practices and efficient operations for wastewater treatment. Therefore, if we don’t have efficient wastewater treatment in place, we don’t have direct potable reclamation. Grammans Water Care Wastewater treatment plant is an important component of the ongoing success of direct potable reclamation.
Grammans Water Care Works is a biological wastewater treatment plant that was built between 1959 and 1961 but commissioned in 1963. It was constructed with the initial capacity of 9 megaliters a day, which increased to 25 megaliters a day, its current capacity. It was designed to treat water from domestic origin. The industrial wastewater is diverted to another plant mainly to protect the direct potable reclamation plant from hazardous waste.
This allows to plan for Windhoek and the country, and Gammans serves as an important link in the water circle because it treats water, which is directly reclaimed for potable use, which serves partially towards meeting the water demand of the Windhoek potable water needs.
Chart 2 (see attachment) shows in- flow water into Gammans and then the supply water to the reclamation plant, and the product works into the reclamation plant. Of the effluent water received at Gammams, 75% is supplied to the direct potable reclamation plant. Of the water that is supplied, 85% is the direct potable reclamation plant intakes. of the intake, 92% is produced and then blended with other conventional sources for distribution.
With water reuse being recognized as the main alternative to reduce water demand or water consumption, Namibia as a water-stressed country must find ways to take advantage of all the drops of wastewater to increase the reuse potential. Therefore, another direct potable reclamation project was identified as one of the medium-term interventions to upgrade or improve water security. But for this project to be feasible, additional upgrades are required for the Gammams wastewater treatment plant and another municipal plant, in order to ensure that there is sufficient water at the right quality.
Sewage sludge disposal has become a costly and environmentally challenging matter that requires an innovative approach. Agriman (Pty) Ltd is a South African based company with an international footprint that provides a complete value chain solution for the handling, processing and beneficiation of wastewater sludge to a commercially marketable fertilizer.
Depending on existing infrastructure and processes employed at a wastewater treatment works (WWTW), Agriman has developed the ability to migrate upstream in the process line to perform and manage critical functions related to the digesters and dewatering of sludge that have a direct effect on sludge quality. By means of accelerated solar drying, sludge is dried and stabilized before disinfection and granulation takes place. Once granulated the product is then blended with conventional fertilizer feedstock to customer requirements for agricultural use, effectively transforming a hazardous waste into a registered organic fertilizer that is safe for agricultural use.
The environmental, economic and socio-economic impact of the traditional disposal methods of wastewater treatment works’ sludge is not a sustainable solution. Authorities are also being pressured by laws and legislations that are phasing out the disposal of sludge at landfill sites. Provided that dewatered sludge can be dried cost effectively at a specific WWTW, Agriman can provide a sustainable long-term alternative that can be implemented on a large scale to safely handle and process sludge to an organic based fertilizer. The trend towards sustainable farming practices creates a high demand for commercially available organic fertilizers to supplement chemical fertilizers. This demand is currently not being met. The potential to commercially beneficiate wastewater sludge to a registered and approved agricultural fertilizer on a global scale has been shown by Agriman as a model that is economically viable for wastewater authorities, the agricultural industry and sustainable development.
AAEA