Replication Potential of the Uhuru Park Pilot Project from Kenyan Perspective

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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.

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Pilot Project for Wastewater Treatment and Reuse at Uhuru Park Nairobi

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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:

  • The river that flows in Nairobi is polluted enough and needs to be cleaned to get the same quality as before the settlements. So, there are a lot of projects ongoing to make this river cleaner and for a better environment.
  • Secondly, Nairobi City water production is around 500 000 m3/day, but the amount needed to meet existing demand is 800 000m3; there is a lack of green water to use.
  • Furthermore, there is lot of drinking water used for some needs that technically safe recycled water could have met (flushing toilets, irrigation, etc.) Indeed, water reuse systems can reduce the water demand by 50% (800 000m3/day is necessary. If 50% of water are saved, then only 400 000m3 will be needed). To implement this project, infrastructure upgrade is not necessary.

A pilot plant was thus installed at Uhuru Park, Nairobi for two purposes:

  1. clean up the Nairobi river a little bit, and
  2. help reuse water.

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.

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The Way of Bremen-Seehausen to an Energy Neutral Plant

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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 first one is the repowering. Three (03) combined heat and power units were renewed. Every unit is around 1.4 megawatts electric per unit, and a wind turbine (see Attachment, Page 9). What comes from the combined heat and power plant can be used to improve the gas production.
  • Some projects are also ongoing to have a higher gas production, including a demand reduction in a technical way by specific reinvestment. It was also economically viable to get new aggregates with the lower specific demand. For example, in this case a compressor hall with seven (7) Compressors for the appropriation of in-house processes.
  • The third pillar is optimization. There is a digital twin of Bremen’s treatment plan for all biological processes. This allows for optimized process, and especially the aeration, the quantity of oxygen needed for the microbiology part. Some set of DWA A- 216 rules described in the presentation (see Attachment, Page 11) can also be used to view how much energy is needed, and if there may be a possibility to reduce it a little bit more (how to do an energy check, an energy analysis for wastewater treatment plant in Germany, with guidelines through the whole calculation process). An energy analyzes enables to see the best value that can be reached for specific energy demand for the treatment plant, with a highlight on the quantity of energy that can possibly be reduced in future projects.

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.

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Wastewater: A valuable Resource

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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:

  • Windhoek has the highest population growth rate that increases the water demand proportionally;
  • Windhoek is also synonymous for irregular or erratic rainfall patterns, which result in the lowest average rainfall, for annual rainfall of about 300 to 400mm. A low annual rainfall with the high annual evaporation of about 3000 to 3500mm;
  • Windhoek experiences regular drought and the ephemeral rivers that are closed to this city are fully exploited;
  • The perennial waters sources that are located closed to Windhoek are too far away. The Okavango River for example is 700km away, and the Atlantic ocean is about 3500km away.
  • The main perennial rivers are national borders originating in the neighboring countries, which means that the long- term agreement on water exploitation cannot always be guaranteed;
  • The portable water sources closed to Windhoek in close proximity have been fully harnessed.

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:

  • First, the groundwater supply and the three-dams system, owned by a state- owned enterprise called NamWater, which is the country national water utility and bulk supplier;
  • Second, the reclaimed water or direct potable reclamation, with reclamation of potable water directly from sewage effluent that is produced and provided by a wastewater treatment plant called Gammams water care works wastewater treatment plant.

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:

  • Windhoek is indicated in the green square, central Namibia (See centre of Map 1 in attachment). So, the three- dams system that belongs to the state has the largest capacity; it consists of the Omatako dam (212 km from Windhoek) which is built in the Swakop river. Besides the rainfall, it gets supplemented by a scheme further up north and a state-owned scheme called Von Bach supply scheme from underground water; then the water is pumped into a canal called the eastern national water carrier located 430km away from Omatako dam, and which transports water to Omatako dam.
  • Then, the Von Bach dam is about 70km from Windhoek. So, water is pumped from Von Bach dam and is treated in the Von Bach purification plant; the water is then piped to Windhoek for supply. This water is finally blended with the direct potable reclaimed water and or the underground water for distribution.
  • The Swakoppoort dam (125km from Windhoek) is the largest one, which is built just downstream of the Swakop river.

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.

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Commercialization of Wastewater Sludge Beneficiation

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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.

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Bisol Systems for Waste Water Management

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Bisol is a company started by a team of young civil engineers, and environmental enthusiasts, who are passionate about solving sewer problems and improving water sustainability. Their products are engineered and custom made to manage sewage and also recycle the sewage back to water for sanitary needs in short non-portable water that will be used for flushing toilets, cleaning the compounds, irrigation of the lawns, and farm irrigation.

The company works with institutions, private owners, and commercial businesses to promote wastewater recycling. The prospects is to be able to reach a large magnitude so that the company can improve sanitation in the region and water security.

Some of its products such as bio-toilets improve sanitation in schools and promote stability. There are also ultra-modern biodigesters that reduce and completely stop pollution, and a compact sewage recycling system that recycles sewage, treats and recycles water from the septic or biodigester and turns it into clean clear water.

Some of the systems presented in the attachment are Bisol’s own innovations and modifications. The company thus proposes custom- made solutions for different setups, through wastewater management consultancy team.

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Underground Sewerage Schemes: Last Mile Connectivity

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To keep up with the demands of rapid urbanisation, the Government of Tamil Nadu (GoTN) has accorded priority to implement Under Ground Sewerage Schemes (UGSS) in all the needy Urban Local Bodies (ULBs) through different financial schemes in a phased manner. The GoTN has made efforts to reach the ‘last mile’ with adequate and equitable sanitation and hygiene in ULBs of Tamil Nadu.  This paper aims to draw insights into the underlying factors and initiatives taken by the GoTN for the UGSS last-mile connectivity in the state.

Indeed, in a state like Tamil Nadu (TN), sanitation is essential for enhancing the quality of life and health and improving productivity. In this regard, GoTN has taken initiatives in UGSS implementation and also in Fecal Sludge Management (FSM) in a phased manner to reach last mile, which are broken down into three stages detailed in the full article attached herein: i) from 2000 to 2008; ii) from 2008 to 2017; iii) from 2018 to present.

Apart from the financial support initiatives to the households, dedicated Information, education and communication (IEC) programmes were also conducted in different parts of the state to educate the households on taking the service connections to avoid direct disposal of wastewater to the stormwater drains or the neighbouring lands.

For the ULBs which are not covered under the UGSS implementation scheme, a separate plan had been prepared on FSM for safely managed sanitation in the state. The timeline of legal and regulatory framework associated with FSM initiatives are given in the full article attached herein.

The use of water supply and sewerage connection deposits, interest-free loans, and taxes in Tamil Nadu suggests that long-term sustainability of sewerage systems can be achieved with policy commitment, effective project appraisals and citizen involvement. The efforts by GoTN on UGSS last-mile connectivity can be taken as a reference by other states to improve the last mile with inclusive sanitation. The major lesson learned from the UGSS implementation is that the selection of towns for the implementation has to be based more on public demand, their capacity to pay back the loan amount, and the financial capability of the ULB than on the readiness of the DPR for the project.

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Share Water No. 13

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The thirteenth issue of the African Water Association (AfWA) technical and bilingual magazine, Share Water, is now available. It provides solutions in terms of guidelines and tools likely to help manage the WASH businesses efficiently and mitigate the shortage of water supply, for improved access to sustainable water and sanitation services for all in Africa.

Among these solutions, the water safety plan (WSP) approach is widely recognized as the most reliable and effective way to consistently manage drinking-water supplies to safeguard public health. Since the introduction of WSPs in the third edition of the WHO Guidelines for Drinking water Quality (GDWQ) and the International Water Association (IWA) Bonn Charter for Safe Drinking Water in 2004, a significant number of water suppliers have implemented WSPs, and many governments are actively promoting their implementation and/or inclusion in national legislation.

Some benefits of WSP implementation include the promotion of public health by continuously assuring safer drinking-water for consumers, the setting up of a proactive (rather than reactive) framework for managing drinking water quality, the early identification of new/increased risks-incidents, the in-depth systematic evaluation of water systems, and much more…

 

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Zoom : des équipements pour l’approvisionnement en eau et le traitement des eaux usées

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Les solutions du groupe AVK interviennent à ce jour dans tout le processus de l’eau ou cycle de l’eau, du pompage au traitement, en passant par le réseau de transfert, de distribution et de traitement des eaux usées. Les équipements fabriqués et commercialisés rentrent dans la gamme des vannes à opercule (jusqu’à 2500 de diamètre), vannes à papillons (jusqu’à 3600 de diamètre) et vannes de régulation ou intelligentes, qui permettent de stabiliser une pression ou un débit en fonction de la consommation des abonnés. Ces vannes permettent de suivre le débit journalier et le débit nocturne, pour ne pas rester sur une pression en aval de 4 à 5 barres sur toute l’année alors que le tirage est à forte consommation. Des vannes de branchement avec système de clapet sont également disponibles, et l’entreprise dispose à ce jour d’une des gammes les plus larges de robinetterie et accessoires de canalisations pour l’eau potable ; toutefois, elle ne fabrique pas les pompes.

La vanne papillon est adaptée aux gros diamètres, pour une meilleure gestion de l’encombrement et du regard. Il existe une gamme dont les matériaux sont adaptés aux liquides agressifs ou eaux usées. Les vannes murales et guillotines sont quant à elles utilisées pour les stations d’épuration. La gamme de protection incendie pour sa part, devra être placée sur des poteaux incendie dans les villes afin d’assurer la sécurité des habitants.

La vanne opercule est la plus utilisée dans les réseaux d’eau en Afrique ; bien qu’assez banalisée car enterrée (l’appareil est souvent invisible), elle sert à sectoriser un réseau dans le cadre de la procédure pour déterminer l’Eau Non Facturée (ENF). Si la vanne n’est pas étanche, toute la logique de calcul est fausse. D’où la problématique de la qualité des produits installé sur les réseaux, car très souvent les vannes ne fonctionnent pas et ne sont pas étanches.

Le logiciel AVK Assist peut être installé sur I-pod ou Android pour lire les données des vannes connectées qui disposent d’un code-barres ; par ce moyen, il est possible de géolocaliser l’emplacement de la vanne. Il existe également des fiches techniques et des petits logiciels pour calculer les débits. La vanne intelligente comprend un système de capteurs qui donne à l’exploitant des informations sur la manipulation de la vanne de façon instantanée, et celle-ci ne peut plus être manipulée à l’insu de l’exploitant. Pareillement, cette technologie permet de signaler la manipulation du poteau incendie par une personne non autorisée. Cette technique innovante s’avère très utile pour lutter contre le phénomène de l’Eau Non Facturée, i.e. l’eau produite mais non facturée à l’abonné.

AVK impose sur le cycle de l’eau les exigences qu’elle s’est fixée pour la gestion du gaz. Il y’a un écrou de manœuvres complètement serti englobant dans l’opercule en fonte et entièrement vulcanisé. Il n’y a aucun mouvement, ni vibration entre l’écrou et l’opercule, donc aucune corrosion. Il existe un concept où l’écrou est simplement positionné et un mouvement continuel peut être noté. Aussi, après quelques mois ou quelques années, il y’a un phénomène de vibration et donc de corrosion.

AVK est l’une des seules sociétés qui fabrique le caoutchouc (polymère) utilisé pour ses équipements. Une vanne opercule c’est de l’EPDM compatible à l’eau potable. C’est dire que AVK possède la maîtrise qualitative du processus de fabrication, qui tient compte de la norme européenne EN 681, relative à l’élasticité du caoutchouc et la rémanence (capacité à pouvoir s’écraser quand on ferme la vanne et à retrouver sa forme initiale quand on ouvre la vanne). La certification allemande GSK permet à AVK de garantir la qualité du revêtement époxy sur la vanne. Il existe plusieurs critères de contrôles non destructifs qui permettent de garantir la longévité du revêtement époxy sur les équipements, ce qui empêche toute corrosion de la vanne, même après dix (10) ans d’utilisation. En tant que garantes de la qualité de leurs réseaux, les sociétés d’eau gagneraient à tenir compte de ces certifications.

Le concept de vannes à brides peut être multiplié en différents types de connexion. Même si la vanne opercule est le nouveau produit lancé, il existe plusieurs pipes en PEHD dans la sous-région. Il s’agit d’un équipement dont les 02 embouts sont très manchonnés, sans aucun boulon à serrer et sans couples de serrage à respecter ; il suffit de souder les tubes PEHD sur les embouts qui sont déjà sertis et testés en usine. L’avantage du PEHD est la garantie d’un niveau zéro de fuites, car le polymère peut être soudé.

Les bouches à clé vont de pair avec les vannes, car elles constituent le point d’accès de la vanne par lequel il est possible de faire de la recherche de fuites grâce aux logeurs, entre autres systèmes de qualité, qui permettent d’écouter le retour du réseau. À la suite des vols de fonte et à la demande des clients, AVK s’est orientée vers des matériaux composites qui sont recyclables, économiques, non corrosifs, ne peuvent pas être volés et consomment moins d’énergie afin de répondre aux exigences énergétiques actuelles. Une nouvelle bouche à clé en tête fonte, tout en composite (tête ronde, marquage hexagonal, couleur dédiée, numérotation, etc.), qui peut être réhaussée pour s’ajuster sous la chaussée au passage des véhicules a été lancée. En effet, l’un des problèmes récurrents est l’écrasement de la chaussée par les gros porteurs (véhicules à fort poids), qui laisse en saillance la bouche à clé ; elle reste donc en hauteur par rapport à la chaussée. La solution proposée va suivre le mouvement de la chaussée, et assurer une continuité constante entre la tête de la bouche à clé et la route, qui facilitera la manipulation de la vanne au cours des années à venir dans un souci de durabilité. À la demande des clients, elle est en cours de développement et de vente en Afrique.

L’origine de l’ENF peut être les fuites dans les vannes. Aussi, des équipements de réparation de conduite revêtent une importance majeure. Il s’agit des solutions ou manchons toute pression, tout matériau (pipe en PVC, PHP, acier, etc.) et tout type de pression (jusqu’à PN=40) qui permettent de réparer les canalisations ou conduites en charge sans couper l’eau. Les informations sur le type de conduite, le diamètre extérieur et la pression permettent de fabriquer des manchons dédiés pour résoudre rapidement et à faibles coûts les problèmes de fuites, évitant ainsi les coupures d’eau intempestives.

L’emboiture de deux (02) canalisations en PVC ou en fonte qui ont des fuites peut également être réparée. Les avantages comprennent la simplicité de la réparation qui est définitive et garantit l’étanchéité sur le long terme, sans coupure de tube, sans déterrer la canalisation et sans coupure d’eau afin de ne pas perturber les utilisateurs finaux lors du processus.

 

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A Non-Intrusive Technology for Network Performance Control

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The ultrasonic flowmeter is a tool for network performance control and preventive maintenance in handheld and fixed station. The principle of operation is the set of two (02) sensors on the same side of the pipe with sending of a wave on the side, which is reflected on the pipe that arrives on the second sensor. The 2nd sensor does the same thing and sends a signal which will be recovered by the other sensor. Depending on the direction of the flow rate and the speed, a difference in travelling time will be noted, which allows to measure the speed. As it applies to any measuring tool, the external diameter of the pipe or the wall thickness and the nature of the material should be set up.

The advantage of the ultrasonic flowmeter lies in its non-intrusive technology. It adapts itself to the environment and places itself on the pipe, without the need to take over the pipe or cut it. Moreover, it is not necessary to carry out important works for the setting up of the flowmeter. Its sensors allow it to adapt to different types of pipes, as they adjust to the pipe and can be installed on all types of networks, mainly in metal, non-metal network, PVC, PE, concrete, cement, asbestos, etc., ranging from 25 to 4700 in diameter.

The measurement is bi-directional and without loss of load because there is no contact with water. Sensors can be placed in different locations and require little space depending on the diameter and the nature of the material. The spacing between the sensors does not have to be very large.

The handheld tool is a small object that can be held in the hand, depending on the manufacturer and the pair of sensors, with a system that allows sensors to be tied to the pipe.

The fields of application are quite diverse. The ultrasonic flowmeter allows to control the performance of networks, in addition to or as an alternative to fixed sectorization, which is quite developed in the world. The performance of a drinking water network is controlled by measuring its flow rate, especially the night flow rate. The sectorization allows to identify the leaking sectors and to prioritize the research areas on which to carry out priority actions of leakage research, frauds, and network renewal, etc.

The watertight valves allow further reduction of the sectors through valve operations, changes in hydraulic sectors during the night, over several days or instantaneously depending on the research zones. They also allow to quantify the losses on the night flows rate, and then to carry out a ratio of the losses to check the performance of the network in the concerned areas to initiate or not corrective actions. They are further used to check the sectorization in place, especially the large meters and flowmeters that are already in fixed stations, which is a strategic focus for operators of water networks. The control is performed upon insertion, thanks to the presence of a fixed sensor that needs to be handled using an ultrasonic flowmeter, which can be an electromagnetic flowmeter, a mechanical meter, etc.

Some customers use it to check the large meters of big consumers before they validate the metering, given the financial impact of under-metering on large consumers. Data from the checking of fixed sectorization meters is used for the analysis of good or bad operation of a network. Failure to measure from the fixed meter has an impact on the operation and performance of networks. To check the pump flow rates, it is necessary to set the sensors on the pipes at the pump outlet and validate the nominal flow rate of the pump, i.e., identify if the pump is operating properly or if there is a need for maintenance.

It can be used upstream of works when defining the profiles of consumption, of distribution, of a suppressor, or the profile for the renewal of pipes. It is possible to set the device over several days to record the minimum, maximum and average flow rates, which will allow the correct dimensioning of works, i.e., avoiding having pipes or conduits that are too large or too small and using a suppressor adapted to the area.

Some images in the presentation below show the successive launch of four pumps to reach the desired flow rate in the drawdown to make the controls, and different examples of implementation. In the first example, the fixed insertion probe sends its data through a remote transmission system to the customer’s supervision software. The customer’s leak detection team had performed three unsuccessful researches for 20m3 of leaks in a specific area. Back to the starting point, there was a 20m3 difference between the handheld ultrasonic flowmeter that was set up and the insertion probe. The drift of insertion probe that occurred, resulted in a miscalculation of a measurement point and consequently a loss of operation due to the time spent to look for leaks where there were none.

Regarding the comparison with electromagnetic flowmeters, the connection with the flowmeter in place can sometimes run smoothly, but we can also observe electromagnetic interference defects on the electromagnetic meter that lead to a metering defect and a corrective action by the customer. In one of the cases encountered, one of the electromagnetic meters had got a large leakage rate, and the doubt of leakage was persisting. In fact, there was a 4 to 5 cubic meter difference that made it impossible to find the location of the leak, as the customer could not find their way around. The laying of an ultrasonic flowmeter allowed to detect the problem quickly. Example 2 (see presentation) is a DN300 stainless steel pipe on site where a pump flow rate had to be checked. The more the pipe will be larger, the greater will be the spacing between sensors. In case of no fixed flowmeter, it is possible to use the handheld ultrasonic flowmeter as a starting point to carry out checking for leaks, fraud and validate the proper functioning of a network. As a reminder, the minimum flowmeter is connected to the existing network.

That handheld measurement tool can be used by different departments: the distribution, performance and network department can be interested in leakage research feature, flow rate measurement feature and linear loss index ratio; production and maintenance department can use it to validate pump flows rate amongst other items that leaves the factory; metrology and metering department for the checking of fixed station meters; engineering offices and works department for the realization of hydraulic profit before works (e.g. modification of pipes, suppressors…) and quality department to validate performance of the network, etc.

Framework for the use of fixed ultrasonic flowmeter may varied. The handheld tool is multi-service and adapts itself to the environment. The use of fixed station is more restrictive, given the need to be tied to a point. Sensors are the same for handholding and fixed station. The difference lies in the unit, which will be fixed and close to the pair of sensors for the recovery of data from sensors and communication link with the remote transmission system for retransmission to a supervision software. The interest is obvious when it comes to large diameters of minimum DM400. Under that size, it is possible to use a fixed station to handle a fragile pipe, that one does not want to touch (the interest here lies in the non-intrusive side and the absence of important works for laying the equipment). However, it is suitable to be rigorous on the straight lengths to be respected for a better long-term precision.

The ultrasonic flowmeter is used for both drinking water and wastewater because the flow rates of condensate pumps are also checked by sanitation departments. The checking of flow rate pressure pumps with fixed station is also carried out for wastewater. To achieve the accuracy of wastewater measurement with the ultrasonic flowmeter, the pipe must be full. Sensors can be buried and immersed for a long time at fixed points. Pumps with inverters allow flow rate measurements to be tested even when water is loaded.

SEWERIN is a German manufacturer of equipment for improving the performance of water systems, mainly water leakage detection and Non-Revenue Water (NRW) improvement.

 

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