A universal right: have access to safe drinking water


n 2015, the United Nations General Assembly set up 17 Sustainable Development Goals (SDG) to “achieve a better and more sustainable future for all” by 2030. The SDGs are globally interlinked and include, among others, the end of poverty in all its forms, reduction of inequalities, climate actions, and a turn into more affordable and sustainable energy. In particular, SDG 6 focuses on ensuring availability and sustainable management of water and sanitation for all. Figure 1 shows the six key targets and the two additional targets for resource mobilisation and policy to be achieved within SDG 6 [1]. Access to safe drinking water and sanitation is essential for the realisation of all human rights and the development of life. However, despite the growing involvement of all countries, there is still a long way to go. In 2020, billions of people still lacked access to safe drinking water, sanitation, and hygiene [2].

Figure 1. Key targets for SDG 6, modified from [1].

Water and sanitation are at the core of sustainable development since they would help at the same time poverty reduction, economic growth, and environmental sustainability [3]. Nevertheless, overexploitation, pollution, and climate change have led to severe water stress in places across the world, worsening the situation with increasing disasters such as floods and droughts. 80% of wastewater in the world flows back into the ecosystem without being treated or reused, and 70% of the world’s natural wetland extent has been lost due to anthropogenic causes, including a significant loss of freshwater species. The consequences of lack of safe water are lethal: according to the UN’s 2018 annual report on the SDGs, around a thousand children die every day due to diseases related to poor hygiene and quality water [4].

Moreover, COVID-19 pandemic posed an additional impediment in accessing safe water and other sanitation and hygiene services, which on the other hand, were needed to prevent the spreading of the virus [5].

Household water treatments and safe storage (HWTS)

Most of the population without access to safe water is in developing countries where lack infrastructure and financial resources. Providing access through centralised systems would indeed be very challenging. Large distribution systems involve a lot of operation and maintenance, and water can get contaminated during the distribution or handling in the household [6]. Low-cost, easy-to-use and sustainable domestic treatments are needed in these locations. Household-level Water Treatment and Safe Storage (HWTS) is the most cost-effective intervention that vulnerable populations can rapidly implement in developing countries to improve microbial water quality and reduce waterborne diseases [7]. HWTS is a multi-barrier approach with 5 steps that equally contribute to reducing the risk of unsafe water (shown in Figure 2). The multi-barrier approach is the best way to minimise the threats coming from drinking unsafe water. Waterborne pathogens can be eliminated by household water treatment like boiling, chlorination, separation with specific ceramic filters (filtration) or adding chemical coagulants to agglomerate the pathogens, settle them and separate them (flocculation). Relying on more than one technology to improve water quality is key to ensuring high decontamination from protozoa, bacteria, and viruses and reducing the health risks associated with them.

Figure 2. Household water treatment and safe storage multi-barrier approach

Source protection

Actions should be taken to improve the water sources or points of collection. This can include regular cleaning of the area around, moving latrines away or downstream, and building fences to prevent animals from contaminating open water sources.


Gravity settling is the simplest household water treatment and safe storage (HWTS) method. It removes some turbidity and improves the visual appearance, although it is limited in pathogen removal and can be affected by secondary contamination. Coagulation enhances settling making the particles stick to each other. However, coagulation is affected by several factors such as temperature, pH, and coagulant dose. Sedimentation alone is not a complete treatment but allows subsequent treatment steps to be more effective.


Membrane filtration is a rapidly growing field in water treatment. There are different kinds of membranes based on size exclusion mechanism, electrostatic effect and biological activity. The main configurations include dead-end, cross-flow, flat sheet, and hollow fibres, and they provide a good barrier to particles, protozoa, bacteria, and viruses. It has a simple operation without affecting the taste and reduces turbidity. However, the main drawback is the membrane fouling, which results from particle retention, and increases the operating pressure. Fouling can be reversible or irreversible but can be limited by regular backwashing and periodic cleaning. Also, filtration does not protect against recontamination.

Ceramic filtration consists of ceramic pot filters and candle filters. It has a simple operation and can be produced locally without electricity. It is also socially accepted and highly used in developing countries. However, it has moderate effectiveness, variable water quality, and no residual protection.

Biological filtration mainly includes biosand or slow sand filtration. The biological layer takes time to develop, but it does not need backwashing, although other cleanings may be needed. It’s possible a long-term use, but there is a high risk of recontamination.


Heat is the oldest HWTS, and it is widely accepted, understood, and promoted. Boiling water is effective against all viruses, bacteria, and protozoa, and turbidity is not a problem. However, it takes a long time if we include cooling, and there is a high possibility of recontamination.

Ultraviolet radiation is effective with most bacteria, protozoa, and viruses and can be artificial or natural. The dose is calculated as intensity*time, and typical doses consist of 400 J/m2. UV-C lamps can act directly on the DNA while using natural sunlight through the Solar Disinfection process (SODIS) we can exploit the UV-A and UV-B spectra of the sun. SODIS consists of exposing PET bottles for 6 hours in good weather conditions. UV treatment is highly effective and, in the case of SODIS, is also simple and inexpensive. However, it takes time and depends on turbidity. Furthermore, when using sunlight is highly dependent on climate conditions.

Chlorine is a chemical disinfection and the second most reported HWTS. Chlorine is a strong oxidant and acts on the cell wall, DNA, and enzymes. It is highly effective, other than simple to use and low cost. Furthermore, it gives residual protection when the water is stored. The main drawbacks are the change in the taste and odour, the ineffectiveness against protozoa at small concentrations, and the formation of by-products.

Safe Storage

Even if household drinking water is treated, it may still become re-contaminated through storage in dirty or uncovered containers or through contact with dirty hands and utensils. Appropriate containers are designed to minimise recontamination. Hygienic location is also important as environmental contamination can easily affect the final water quality. The containers should have a lid or be narrow-necked to limit recontamination.

ESCAPE ROOM: Save the population from water scarcity

In the following link you have access to my escape room about water treatment. Learn more about it, challenge yourself to solve the riddles, and find the key to saving the population from water scarcity.

https://docs.google.com/presentation/d/1Bc6ZaYtM_e_o8kQ3DOKal53YA2nkU0IUqI_kIAJQbG4/preview#slide=id.gf90f95fc23_0_2 (in English)

https://docs.google.com/presentation/d/1a88X7-rcjRJbMdSVzlThhoMJRbf0NeIudHxO3d2cMVo/preview#slide=id.gf90f95fc23_0_2 (in Spanish)


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[6]        Household Water Treatment and Safe Storage (HWTS). SSWM – Find tools for sustainable sanitation and water management! Available at: https://sswm.info/sswm-solutions-bop-markets/affordable-wash-services-and-products/affordable-water-supply/household-water-treatment-and-safe-storage-%28hwts%29 (accessed December 16, 2021).

[7]        The International Network to Promote Household Water Treatment and Safe Storage. Available at: https://www.who.int/household_water/advocacy/combating_disease.pdf (accessed December 13, 2021).

Towards Smart and Resilient Cities


he World’s inhabitants moving from rural areas to cities are in continuous increase. Cities with high inefficient transportation systems and poorly designed buildings, and with high consumption of quantities of fossil fuels and high levels of greenhouse gases emission, are headed to an inevitable collapse. In response, smart cities can replace today’s carbon-consuming urbanism with a new sustainable one. Thanks to the integration of information and communication technology (ICT) and various physical devices connected to the IoT (Internet of things) network, transportation systems, and buildings can be developed towards greater sustainability and resilience [1].

Smart cities aim to improve efficiency, equity, and quality of life by using collected data from different types of electronic methods and sensor with the purpose of improving and optimizing the operations and the management across the city, such as traffic congestion, energy usage, water supply networks, waste, and air quality. In the smart city concept, the community interacts directly with the city infrastructures and services, giving a contribution to the data collected and develop a real-time response which also prepares the city to respond quickly to challenges. Thanks to the use of ICT, the empowerment of citizens is largely emphasized to create a widespread sense of social cohesion, awareness of the relevant issues, and active support of the citizens.

Climate change, water scarcity, and growing waste are three of the main environmental issues challenging in contemporary cities. The resilient city concept aims to increase the quality of life by absorbing and adapting any heterogeneous stress factor and guaranteeing citizens’ safety. Consequently, the integration of the two concepts, as shown in Figure 1, improves simultaneously and synergically the whole city concept. Mitigation strategies combined with adaptation strategies are key to counterbalance possible catastrophic impacts and to absorb the effects of hazards through adaptation and transformation.

Figure 1. Smart and resilient city value chain [2].

To achieve the goals of smart and resilient cities, electrical infrastructures, called smart grid, have a key role in the energy transition. Important objectives of smart grids are the implementation of renewable energy technologies to power entire urban areas, achieving net-zero carbon dioxide emissions, decentralizing power, water, and waste in small-scale systems, endorsing green infrastructure, moving from liner to circular systems, increasing communication among cities and regions in a bidirectional way, and finally achieving “electrification” which refers to transportation supplemented by electric vehicles. Figure 2 shows the expected structural changes from a traditional to a smart system in energy management, made possible by the increased use of digital tools.

Figure 2. Characteristics of a traditional system versus a smart system [3].

To promote the smart and resilient concept, the European Commission has launched the European Innovation Partnership for Smart Cities and Communities (EIP-SCC), with the aim to support the energy production, distribution, transportation, and digital technologies and to improve services while reducing energy, as well as greenhouse gas emissions and resource waste [4,5].

In smart cities, circular economy is a key concept. Our global consumption is exceeding the capacity of the planet to regenerate, and because of this, it is important to shift from a linear to a closed-loop system. The main idea is to minimise the use of resource inputs and the creation of waste by reusing, repairing, and recycling. Waste materials and energy are input for other processes. The circular model has to be employed in every industrial sector, in the economic, social, and environmental production and consumption. An example of the circular economy application is the recovery of nutrients and the production of bioplastics from daily processed wastewater streams. Also, the scarcity of water is already a serious problem and many territories have been affected by water shortages, which are destined to worsen as a result of climate change [6]. Therefore, the need to encourage the use of alternative sources of water and the reuse of wastewater. Furthermore, the need to focus on the sustainable use of natural resources, the fostering of environmental remediation, the improvement and enhancement of ecosystems, the management and protection of water and air quality, the monitoring of the response to environmental threats for human health.

In the face of climate change, it is important to develop solutions, technologies, and financial response to possible impacts. A key asset of smart and resilient cities is the dynamic interplay of learning capacity, persistence, adaptability, and transformability across multiple scales, as shown in Figure 3 [7,8]. The model is structured as a cyclical process characterized by three different stages connected through a feedback loop: strategies’ definition, implementation, and management. Along the process, there are different periods: short, medium, and long term. In the short term, strategies are orientated to improve cities’ capacities to climate-related impacts by increasing systems’ persistence. In the medium term, cities enhance their capacity to deal with unexpected impacts by improving systems’ adaptability. In the long term, strategies should drive the urban transition towards the prevention of future climate-related impacts by improving cities’ transformability.

Figure 3. The conceptual model for building up smart and resilient cities in the face of climate-related challenges [9].

The capacity of continuous and dynamic learning is crucial for the smart and resilient city concept. Learning capacity can be improved using several approaches such as networking, the ability to connect people and devices for exchanging data and information, monitoring, to detect conditions of urban system, knowledge, to elaborate the information, memory, to learn from past events and predict possible future scenarios, and collaboration and participation, to involve people in the decision-making process [9].

To conclude, it is important to move towards smart and resilient cities for both our safety and the one of our Planet. The aim is to live in a city capable to optimize and interconnect the components that characterize the urban systems by taking advantages of the modern technologies and the big data available. A creative city able to reinvent a new equilibrium against destabilizing external stresses and to adapt to new circumstances.


[1]        R. Chapman, Resilient Cities: Responding to Peak Oil and Climate Change, Journal of Urban Design. 17 (2012) 301–303. https://doi.org/10.1080/13574809.2012.666179.

[2]        A. Visvizi, C. Mazzucelli, M. Lytras, Towards an ICTs’ enabled integrated framework for resilient urban systems, Journal of Science and Technology Policy Management. 8 (2017) 227–242. https://doi.org/10.1108/JSTPM-05-2017-0020.

[3]        Bartz/Stockmar, Smart Grid – Staying big or getting smaller, (2018). https://commons.wikimedia.org/wiki/File:Staying_big_or_getting_smaller.jpg (accessed April 2, 2021).

[4]        European Commission, Energy and smart cities, (2020). https://ec.europa.eu/energy/topics/technology-and-innovation/energy-and-smart-cities_en?redir=1 (accessed April 2, 2021).

[5]        European Commission, Analysing the potential for wide scale roll out of integrated Smart Cities and Communities solutions, (2016). https://smart-cities-marketplace.ec.europa.eu/sites/default/files/SCC Solution 80 Best Practice Examples.pdf (accessed April 5, 2021).

[6]        ENEA, Circular management of water resources, (2021). https://www.fondazionesvilupposostenibile.org/gruppo-di-lavoro-per-la-gestione-circolare-delle-risorse-idriche/ (accessed April 3, 2021).

[7]        C. Folke, S.R. Carpenter, B. Walker, M. Scheffer, T. Chapin, J. Rockström, Resilience thinking: Integrating resilience, adaptability and transformability, Ecology and Society. 15 (2010). https://doi.org/10.5751/ES-03610-150420.

[8]        S. Davoudi, E. Brooks, A. Mehmood, Evolutionary Resilience and Strategies for Climate Adaptation, Planning Practice and Research. 28 (2013) 307–322. https://doi.org/10.1080/02697459.2013.787695.

[9]        R. Papa, A. Galderisi, M.C.. Vigo Majello, E. Saretta, Smart and Resilient Cities. A Systemic Approach for Developing cross-sectoral strategies in the face of climate change, TeMA Journal of Land Use, Mobility and Environment. 1 (2015) 1–49. https://doi.org/10.6092/1970-9870/2883.

Learning from the Ozone layer recovery to save the…


he recovery of the Ozone layer is an incredible history that interlaces scientific discovery with citizen action, diplomatic leadership, and technical innovation.

A visualization of the ozone hole over Antartica at its maximum extent in 2015. (NASA Goddard Space Flight Center) [1]

The early 20th century was a very profitable time for inventions. In history, inventions have often helped humans to survive, made tasks easier and led to a jump into the future. Although, there are inventions that at first seem to make tasks easier and solve problems, then they are found to be very unhealthy for humans and corrosive for the environment. [2]

Thomas Midgley in his life won multiple prestigious awards thanks to his inventions, leaded gasoline and chlorofluorocarbons (CFCs), which solved big problems of the early 20th century. It was only after his death, that his fortune declined. Now, Midgley has a different reputation and is considered one of history’s most dangerous inventors. In those days leaded gasoline was sold from the Ethyl Corporation as tetraethyl lead, only mentioned as TEL when marketing, as the dangers of lead poisoning were already well known. Leaded gasoline was invented to eliminate the “knock”, a common engine problem at that time, and it was found to also enhance the engine performance and speed. After many cases of lead poisoning and a string of health maladies, it was only at the beginning of the 70s that TEL was banned and almost completely phased out. The other problematic innovation was chlorofluorocarbons. Back in the 20s, there was a long-standing problem with refrigerators; they were extremely unsafe. In the beginning, ether and ammonia, both very flammable, were employed. Then, they were replaced by sulphur dioxide, not flammable but very toxic. In the first case, fires and eventually explosions were common, in the second case a tiny release of the gas killed families. In 1930, Midgley with a team of scientists found a solution: the world’s first CFC. With the knowledge of those days, CFCs were the perfect safe solution, they became ubiquitous in refrigerators and cooling units, and they were used extensively as a propellant in aerosol spray cans. [3]

In the late 60s, James Lovelock, an independent environmentalist and scientist, was the first to detect the widespread presence of CFCs in the atmosphere, finding it in all the air samples collected in the Antarctic.  Years later, two chemists, Rowland Sherwood and Mario Molina, interested in Lovelock’s results, found out that CFCs were able to rise into the stratosphere, kilometres above our heads. The sun’s harsh rays were able to split the CFCs apart, which were releasing chlorine and posing a threat to our ozone layer. The ozone layer absorbs most of the sun’s ultraviolet radiation. A lack of the ozone shield would have condemned millions of people worldwide to suffer from an immune system disease, go blind with cataracts, and die from skin cancer. [4,5]

Rowland Sherwood (left) and Mario Molina (right) in the lab at the University of California, January 1975. [2]

For more than a decade, the companies involved in producing CFCs reacted by denying the science and attacking the scientists, as it meant economic ruin for them. It was quite easy for them to negate these discoveries, Rowland and Molina were saying that an invisible gas was destroying an invisible layer, kilometres above our heads

It was the first time in history that the public got involved in the problem, and in the late 70s, the people demanded action and so the government responded

In the mid-80s, the discovery of the Antarctic ozone hole added new urgency, and in 1986, Susan Solomons, NASA scientist, proposed the idea of a 10-year global phaseout through market incentives to rapidly block CFCs commercialisations. In September of 1987, 46 states agreed to cut the use of CFCs and signed the Montreal Protocol. By 1990, this agreement had further support and became the first global phaseout agreement to completely phase out CFCs. Literally a disaster was avoided. Millions of lives saved from skin cancers, and agricultural disaster was avoided. Today the ozone hole is showing signs of recovery. 

An important change in political behaviour also occurred. Now, the environment is a constant political issue. In 2015, the General Assembly of the United Nations drew a plan for peace and prosperity for people and the planet. To achieve a better and more sustainable future for all, they designed 17 Sustainable Development Goals to be achieved by 2030. [6,7]

The Sustainable Development Goals address global challenges including poverty, inequality, climate change, environmental degradation, peace and justice. [8]

It takes time to see the effects of the chemicals. The ozone treaty is our lesson. It showed us what it is possible when citizens are involved in scientific discoveries and have the power to influence diplomatic decisions, and finally when the nations of the World come together with a shared goal. We need to learn from history. We cannot repeat the mistake of ignoring invisible threats because they are the most dangerous ones. All together we need to fight against climate change and worldwide pollution, starting from our everyday life habits.


[1]            When we saved the ozone layer, we saved ourselves from even worse climate change. https://www.cbc.ca/radio/quirks/dec-14-saving-the-ozone-helped-climate-change-extra-solar-comet-great-auk-extinction-and-more-1.5391393/when-we-saved-the-ozone-layer-we-saved-ourselves-from-even-worse-climate-change-1.5391408 (accessed January 7, 2021).

[2]            We Saved the Ozone Layer. We Can Save the Climate. https://www.nrdc.org/experts/david-doniger/we-saved-ozone-layer-we-can-save-climate (accessed January 7, 2021).

[3]            This 1920s Inventor Sped Up Climate Change With His Chemical Creations. https://www.history.com/news/cfcs-leaded-gasoline-inventions-thomas-midgley (accessed January 7, 2021).

[4]            M.J. Molina, F.S. Rowland, Stratospheric sink of chlorofluoromrthanes: Chlorine atom-catalyzed destruction of ozone, Nature. 249 (1974) 810. https://www.nature.com/articles/249810a0.pdf

[5]            F.S. Rowland, M.J. Molina, Chlorofluoromethanes in the environment, Reviews of Geophysics. 13 (1975) 1–35. https://doi.org/10.1029/RG013i001p00001

[6]            Transforming our world: the 2030 Agenda for Sustainable Development. https://sdgs.un.org/2030agenda (accessed January 7, 2021).

[7]            Achieving the Sustainable Development Goals – General Assembly of the United Nations. https://www.un.org/pga/70/events/sdgs/ (accessed January 7, 2021).

[8]            Take Action for the Sustainable Development Goals. https://www.un.org/sustainabledevelopment/sustainable-development-goals/ (accessed January 7, 2021).