LEDSOL
Enabling Clean and Sustainable Water through Smart UV/LED Disinfection and Solar Energy Utilization
Enabling Clean and Sustainable Water through Smart UV/LED Disinfection and Solar Energy Utilization
Access to clean drinking water is both a human right and part of the Sustainable Development Goals of the United Nations. Safe and clean drinking water is vital to human life but access to drinkable water is not a standard in many countries around the world. Especially in remote areas like rural zones in Africa, people often only have access to water sources such as self-constructed wells or boreholes which are contaminated by bacteria and germs. In Africa, one in three citizens are affected by water scarcity and about 400 million people do not have access to drinking water.
The LEDSOL project is funded under the LEAP-RE programme (The Long-term Europe-Africa Partnership on Renewable Energy), which aims to increase the use of renewable energy via a well-balanced set of research, demonstration, and technology transfer projects in both continents.
The LEDSOL project is fostering renewable energy to provide clean and safe drinking water based on UV/LED disinfection augmented with classical decontamination and powered by lightweight flexible solar cells. The LEDSOL system is designed to be packed in a self-powered wearable backpack with a positioning engine, which offers an easy to use and affordable technology to local population who is off the grid.
A multidisciplinary consortium comprising partners from Algeria, Togo, Romania, Germany and Finland is gathering the needed expertise for the project implementation and for reaching the objectives set up in the proposal.
We have explored the experiments performed and described in litarture for a wide variety of germs in order to establish the functional requirements of the UV/LED module of the LEDSOL system. Based on our findings, we have identified various issues that may arise in the design or operation of the system. We have designed solutions to the identified problems and have compiled a list of components for the future LEDSOL prototype which were then designed in Activity 1.3.
We have analysed in this activity the existing solutions on the market which we can use for the develop of the UV/LED disinfection module. Specifications for both individual LEDs from various manufacturers and integrated LED modules were analysed. These were divided into 3 categories: UV-A, UV-B and UV-C. Based on the performance and price analysis, we have defined the components for the development of the UV disinfection module.
Based on the results obtained as part of the Activities 1.1 and 1.2, we have developed a first model of the LEDSOL, namely the UV/LED disinfection module. We have designed the components using VariCAD, a computer program for 3D/2D CAD and mechanical engineering. We are presenting here several views of the components such as the main body of the module, the caps with quartz windows, the water circulation pipes, the PCBs for the electronics, etc.
We have analysed several water disinfection, filtration and purification systems availableon the market. Their most important specifications are presented, focusing on size and capacity, flow rate, price, water disinfection and filtration methods and power supply (solar/vehicle/plug-in). Finally, a brief comparison with the LEDSOL system is made in order to identify the advantages of the LEDSOL solution for the particular application area targeted in the project.
The project and the results achieved during the first implementation phase were presented as follows: a conference paper accompanied by a presentation at the ICERI 2022 conference; the project website; Linkedin and Twitter pages; the project presentation at the LEAP-RE 2022 Stakeholder Forum held in Preotria; the annual seminar of the Finnish Academy's DEVELOP programme held on 27 October in Helsinki.
Different types of solar panels have been identified that can be considered for powering the LEDSOL system. The main characteristics are that they should be light and flexible. Solar panels were chosen because of their: high efficiency (for those made of monocrystalline material), reliability, reduction of shading effect by parallel arrangement of the constituent sub-panels, weather resistance. Portability is enhanced by their simple packaging and reasonable weight. When travelling, they can be easily and efficiently placed on a backpack. In order to optimise solar panels for the LEDSOL system, we should take into account that their performance depends on several factors, including geographical location and weather conditions. Furthermore, the LEDSOL system is not static and is conditioned by constantly changing environmental variables. Also, because the system has to be portable, the overall weight and size of the components (battery, charge controller and photovoltaic module) are important parameters to consider, along with user safety.
In order to perform the UV disinfection treatment, initially the water must be filtered from impurities so that its turbidity is as low as possible. For this purpose, mechanical filters will be used to remove solid particles and impurities. The choice for these filters depends on the quality of the filtration and the weight of the filters. Two pumps are needed to pump the water: one will pump water from the surface source into the backpack and the second will pump water through the backpack circuit. The operating parameters of the two pumps are dictated by the performance we want the system to achieve. In addition, for the laboratory prototype, it is necessary to use pumps that allow repeated disinfection of its components using aggressive chemical reagents. For this purpose, peristaltic pumps were selected that avoid contamination of the pumped liquids by contact with the mechanical parts of the pump. These are self-priming positive displacement pumps, which can safely run dry.
In order to elaborate the economic documentation, the methods that can be used have been identified and analyzed. SWOT analysis is a method used to project an overview of the company that wants to exploit the results of the project. It works as an X-ray of the company or business idea and assesses at the same time the internal and external influencing factors of an organization, as well as its position on the market or in relation to other competitors with the aim of highlighting the strengths and weaknesses of a company in relation to the opportunities and threats existing at a given time on the market. Alternatively, the initial analysis can be based on canvas models. The Business Model Canvas (BMC) is one of the main tools used to assess the viability of an idea. It is a quick and effective way of summarizing the main ideas of a business case and visualizing the assumptions and hypotheses made. The Lean Canvas Model (MLC) is derived from the BMC and uses a 9-block concept. The Agile methodology can be used to describe to the target users how the final product will be used and what problem it will solve. Agile has a high level of user involvement and includes frequent reviews.
Three types of experiments were carried out: (i) experiments to measure the power distribution of the UV-C and UV-A emitting LEDs as a function of the current injected into each; (ii) experiments to measure the radiation dose as a function of the current through the UV-C LEDs; (iii) experiments to measure the flow rate of water pumped by the peristaltic pump. (i) The power emitted by the UV-A and UV-C LEDs was measured using a Thorlabs S405C power meter with thermal sensor. Measurements showed that the quartz window positioned above the LEDs did not significantly attenuate either the 275 nm or 365 nm radiation. Measurements made with a Teflon tube of different thicknesses (10 mm and 2 mm) did not show a dramatic increase in intensity. (ii) Measurements of the dose obtained at different points along the height of the Teflon tube were made. UVC-LED cards were used for this purpose. These provide a simple and reliable way to validate the UV-C doses delivered by devices producing germicidal radiation in the 260-280 nm range. Small pieces cut from the UVC-LED cards were placed along the Teflon tube at three distances from the UV-C LEDs (1, 10 and 24 cm, respectively) and irradiation was carried out for time durations of 2, 10 and 100 s The current through the UV-C LEDs was kept constant at a value of 350 mA. (iii) The time required to transfer 2 l of water through the peristaltic pump was measured. The flow rate thus determined was 1 l/min for a supply voltage of 24 V and 1.2 l/min for 25 V. The pump head speed under load was determined both visually and by analysis with a Rohde & Schwarz RTE 1054, 500 MHz oscilloscope. The signal on the oscilloscope was obtained using a 1 Ω resistor placed in series with the peristaltic pump. The speed was estimated at 120 rpm.
Dissemination of the project was done by engaging in various activities that contribute to increasing the visibility of the project, the results of the option and their impact. These include events organised by related authorities in the consortium countries, synergies with relevant projects, presentations to students and pupils, publications in conferences and journals (2 ISI and BDI conferences, 2 ISI journals), social media (Linkedin and Twitter), project webpage.
The main components of the LEDSOL platform have been selected and presented as part of this activity. These were selected in by extending the studies and tests from the preliminary stages that determined the required characteristics of the LEDs (e.g., power and spectral distribution), the pumps for the laboratory prototype (e.g., solvent resistance), the pumps for the final device (flow, mass, size, price), the solar panels (efficiency, price, mass) and the filters (filtration properties, size, mass, price).
The LEDSOL prototype for UV treatment consists of a cylindrical treatment chamber made of Teflon which houses the UV-A and UV-C LEDs at the base of the vertical cylinder. A quartz window covers the LEDs. In the LEDSOL UV system, the UV radiation emitted by the UV-A and UV-C LEDs passes into the untreated water through the quartz window at the base of the treatment chamber. The water is pumped into the treatment chamber via the peristaltic pump. The peristaltic pump works through a unique mechanism inspired by peristalsis, the rhythmic muscle contractions seen in biological systems. The peristaltic pump consists of a flexible tube in a circular housing. UV light is a very effective disinfectant, but disinfection can only take place inside the treatment chamber. The percentage of microorganisms destroyed depends on the UV intensity of the LEDs, the contact time of the water with the radiation, the quality of the raw water and the proper maintenance of the equipment.
The average UV-A LED power was measured over a period of two months. The applied current was in the range of 50 and 500 mA, with the voltage varying according to the injected current, and the power output was measured using the powermeter. The variation of the three parameters was plotted in 3D. The average power of the UV-C LEDs was measured over a period of two months. The applied current was in the range of 100 and 350 mA, the voltage varying with the injected current, and the power output was measured with the powermeter. The variation of the three parameters was plotted in 3D. Measurements showed that the quartz window positioned above the LEDs did not induce significant attenuation at either 275 nm (UV-C) or 365 nm (UV-A). The time required to transfer 2 l of water between two graduated containers was measured using a peristaltic pump. The flow rate thus determined varied as a function of the voltage applied to the pump, and the linear variation in flow rate was plotted. Repeated measurements were made, one set of five measurements for each value of applied voltage.
A protocol for the use of the UV LEDSOL system and methodology for maintenance of the system was established. The treatment chamber should be kept clean. For this purpose, commercial products are available for rinsing the treatment chamber to remove any film on the UV source.
For testing the LEDSOL system, the flow rate to the treatment chamber and the intensity of the UV-A LED was varied, with the UV-C intensity kept constant at maximum. The total colony count, also called total viable count, is a quantitatively estimated measure of the concentration of microorganisms such as bacteria, moulds and yeasts in a sample. Their presence is measured in samples incubated at both 22°C and 37°C. The results of the total colony count should be seen as an increasing or decreasing trend relative to each other. After application of UV radiation a significant decrease of two to three orders of magnitude in the total colony count is observed. It should be noted that the total number of colony-forming units only indicates the quality of drinking water and cannot confirm whether it is safe to drink or not. Test conditions are set to isolate the range of organisms that can colonise and cause infection. Due to the diverse number of organisms that can be found in water, testing for the total number of colony-forming units is non-selective. This is different from testing for certain bacteria, such as Pseudomonas aeruginosa, which requires the use of selective media.
The development of the business plan requires both design and validation as well as adaptation throughout the project. A business plan specifies all the elements needed to demonstrate the feasibility of a business, while a business model identifies the elements that make a business work successfully. The areas of applicability have been established, a market analysis has been described and carried out, and trends in the water filtration and purification systems market have been analysed.
Every day, millions of people in rural Africa suffer from lack of access to clean and safe water. This situation is recognised as one of the biggest causes of poverty in Africa, and addressing this challenge promises to achieve socio-economic development goals. The global water purifiers market size was $30.62 billion in 2022 and is projected to grow from $33.65 billion in 2023 to $54.48 billion by 2030, at a CAGR of 7.6% over the forecast period. The global water purifier/filter market is expected to grow at a CAGR of over 7.5% during the forecast period. Various factors, such as increasing awareness about waterborne diseases and technological advances in water purifiers, are mainly driving the water purifier market. High equipment and maintenance costs may restrain the growth of the water purifier market. UV water purifiers and AI-based water purification systems are the latest trends in the market.
An analysis of existing patents worldwide for equipment using UV sterilisation was carried out. For this purpose, the Espacenet database of the European Patent Office (EPO) was consulted. The results of the search are presented below by UV wavelength categories, namely: UV-A, UV-B, UV-C.
Wide dissemination was achieved through participation in events of national and local interest, two scientific publications, webpage and social media pages dedicated to the project.
In this phase, experiments were continued to test the LEDSOL system. The flow rate of the water supply to the treatment chamber was varied and the efficiency of UV-A and UV-C LEDs was checked, separately, by alternately powering them. The efficiency of both types of LEDs was also tested by powering them simultaneously but varying the flow rate of water through the treatment chamber. A significant decrease of three to four orders of magnitude in the total number of colonies was observed after UV irradiation. It should be noted that the efficiency of the LEDSOL system increases when both UV-A and UV-C LEDs are used. However, a decrease in the efficiency of microbial inactivation was found due to the clogging of the UV-LEDs with scale deposits present in the water. The observed clogging was attributed to water infiltration past the quartz window and rubber gasket. The deposits decrease LED efficiency by decreasing the radiation flux. The effect is similar to the LED's power drop to 70% of its original operating power, also known as L70, but this effect occurs after 40,000 hours of operation.
The main goal of the localization model experimentation was to test and collect data to contribute to the development of new positioning algorithms that are robust and usable with low-cost Android devices. Measurements were performed in five countries with multiple mobile devices. CITST contributed with measurements using Samsung A52 and A12 performed in Romania, Rwanda, and Finland. Raw data collected with Android devices were acquired by using the GNSSlogger application. Our results evidenced several aspects. First, we observed that the raw measurements acquired from commercially available GNSS devices acquire quite a lot of noise (with residual errors e.g. multipath, multipath, interference) leading to errors of several tens to several hundreds of meters. Second, we found that we can significantly improve the positioning error by well-chosen algorithms.
In this phase, the UV disinfection module was redesigned because the one developed and tested in the previous phases suffered a significant degradation in performance over time. The reason identified was clogging of the UV LEDs due to water infiltration. These infiltrations are caused by imperfections in the turning of the Teflon tube. Therefore, a new tube was made in which the walls are designed to be printed on a 3D printer from a solvent resistant plastic. To provide the required reflectivity on the walls of the tube these were lined with a Teflon film which has recently been put on the market and which is specially produced for good UV reflectivity. In addition, one side of the foil has a layer of adhesive which has been proven in multiple tests by CITST to be resistant to the disinfection treatment steps.
Widespread dissemination was achieved through participation in events of national and local interest, a scientific publication, and maintenance of the project webpage and social media pages.
In this activity we designed and developed the control module for the LED disinfection unit. It allows individual control of each of the 3 UVC LEDs as well as the UVA LED. It is possible to realize water irradiation with any combination of LEDs. We have designed both the electronics and the unit as well as a dedicated enclosure. The enclosure was 3D printed at CITST.
In the current phase, an improved version of the disinfection unit was realized, which allows water exposure to UV radiation and does not suffer from water loss and subsequent clogging of the LEDs. In addition, the new disinfection unit is equipped with more UVC LEDs than the previous prototype as a result of a redesigned electronics. The laboratory model has been optimized in terms of the number of disinfection units based on tests with 1, 2 and 3 UV tubes. The peristaltic pump has also been equipped with a new motor to allow higher flow rates. Several in house adaptations have been implemented to fit the new motor to the pump head. A diaphragm pump has also been added to the system allowing experiments with flow rates up to 4 l/min.
The LEDSOL platform for the pilot studies, designed as a mobile device (placed in a backpack or carried on the head in a basket), is conceived as a system consisting of three subclasses: the water circuit, the sterilization elements and the electrical circuit.
The water circuit consists of a diaphragm pump, sediment filter (Naturewater 5µ Sediment Filter Cartridge PP-10A), activated carbon filter (Naturewater Activated Carbon Filter Cartridge Gourmet T33) and connecting hoses.
The sterilization elements consist of three UV sterilization tubes, both in the water circuit and between them in the electrical circuit, served by a single source. Importantly, they can operate automatically, independently, to keep the microbiome under control.
The electrical circuit is composed of two electrical supplies, one of which is for the pump and the second for the PCBs in the sterilization tubes, together with connecting cables, a main switch and a control box. The housing was made of extruded PVC and aluminum, while the fasteners were made of stainless steel and plastic. The role of the latter is to protect the components from vibrations caused by the pump and during transportation. To ensure a flow rate of ~ 2.1 L/min, the water circuit was equipped with two flow limiting units.
In this phase, field experiments were carried out using the LEDSOL system developed for the pilot studies and presented in Activity 5.3. Water treatment of three lakes in Bucharest and Ilfov (Snagov, IOR, Teilor) was performed. The treatment consisted of both water pre-filtration through particle and carbon filters, both integrated in the system, and UV treatment. Using the control system developed in Activity 5.1, the UV treatment was varied using several combinations of LEDs. Also, the water supply flow rate was varied and thereby the UV exposure time was varied. The results obtained revealed the following aspects. A significant decrease of three to four orders of magnitude in the total number of colonies incubated at 37 Celsius was observed after the application of UV radiation. Unexpectedly, the efficiency does not increase with the number of disinfection units nor with the exposure time. The water from Lake IOR and Lake Tei contains, unlike Lake Snagov, Faecal Streptococci and Pseudomonas aerugionsa. These are mostly inactivated by treatment at maximum flow rate with three UV disinfection units and almost completely inactivated by using a lower flow rate and thus a longer irradiation time.
In the framework of this activity, the elaboration of the economic analysis documentation was continued by carrying out the PEST analysis in Algeria and Togo. This is important to understand the socio-political-economic context that will influence the commercialization of the LEDSOL platform in these countries. The production costs of the LEDSOL platform as well as those associated with its commercialization were also evaluated. Financial forecasts for five years of commercial operation have been developed. The estimates show that the investment becomes profitable in the third year of operation. The documentation developed in the previous phases has been refined to reflect the developments in the current phase and, by combining all the results from the project, the business plan uploaded into the reporting platform has been constructed.
During this stage, a patent application was filed under the title "Intelligently actuated device for inactivation of microorganisms by UVA, UVB, UVC irradiation" and the number A00744/26.11.2024. The invention relates to a water disinfection unit based on ultraviolet (UV) radiation emitted by a combination of LEDs in the wavelength ranges UVA, UVB, UVC whose operation is controlled by artificial intelligence (AI) based software that determines the sequence and duration of irradiation with certain wavelengths so as to optimize consumption and increase the efficiency of inactivation of microorganisms in water.
The project was widely disseminated through:
Access to safe drinking water is a basic human need and right. Unfortunately, access to safe drinking water is a challenge in many parts of the world, affected by climatic issues or exacerbated by factors such as water pollution or contamination, poor management of water resources and poor infrastructure. With the United Nations estimating that in the near future there will be two billion people without routine access to safe drinking water, research and innovation efforts are focused on finding solutions to this problem.
In this context, the objective of the LEDSOL project was to develop a mobile system that can be carried in a backpack and that can produce 2 liters per minute of drinking water using clean and renewable energy sources. This objective was expanded following visits by the LEDSOL team to Algeria and Togo which revealed the need for a versatile system adaptable to local customs. These include the use of the system in apartment conditions to disinfect water from traditional springs. The system was also intended to be transportable on the head, as Togolese women are accustomed to carrying water. These issues were addressed by a design based on a lightweight, aluminum skeleton that incorporates the water circuit, sterilization elements and electrical circuit. It can be placed in a kitchen as well as in a backpack or carrying basket. The most important innovative aspect of the system is the UV sterilization elements, based on LEDs emitting in three wavelength ranges. The combination of LEDs was optimized during the project to result in low energy consumption but high disinfection efficiency. This particularly important aspect was demonstrated both in the laboratory and in pilot studies. It is the subject of the patent application filed under the project.
The participation in events organized by the LEAP-RE program for the funded projects revealed the huge potential of the LEDSOL project results. The proposed technology will fill a critical need in many parts of Africa by providing access to affordable clean water to a large number of beneficiaries. It will maximize the socio-economic impact by being able to be used in remote areas where the daily effort to provide water takes away, even at young ages, from the time dedicated to education and rest. Other benefits include the promotion of LEDSOL results among involved researchers and their students, both in Europe and Africa, increased employment and gender equality. The sustainable marketing strategy developed as part of the project considers job creation for RE-SAS marketing, maintenance and training. It will promote revenue generation in both Europe and Africa.
IT Centre for Science and Technology
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