Using the sun for water disinfection in Africa

1)Identify a sustainability problem

Contaminated water transmit water borne diseases such as diarrhoea, cholera, typhoid, and dysentery. Approximately, 502,000 people pass away from diarrhoeal death each year. 

SODIS stands for Solar disinfection, and this technological approach is critical for developing countries that suffer from waterborne diseases. 


The initial idea of using sunlight to disinfect water was already used in India a long time ago by putting water into trays under the sun. The fundamental concept of this approach is putting water in a transparent container and placing it under sunlight for 6 hours. When water is exposed to the solar UV light, it damages microbes and repairs endogenous microbial mechanisms. 

The EU funds the technological development of SODIS technologies, and it aims to reduce childhood diarrhoea and dysentery in rural communities. The advanced technology harvest rainwater to meet water demand in deprived areas. In order to avoid contamination, the technology uses reactors that produce energy through solar panels. However, this simple water technology can be implemented at household level by reaching water temperature more than 45 celsius with the solar infrared light. The setback of the technology is that it takes a long time for disinfecting water to a satisfactory level. It also takes a lot more time under cloudy conditions. In order to overcome this setback, low-cost and simple water treatment techniques like solar concentrators/reflectors are implemented to increase radiation exposure.


  • People live in rural areas without access to treated water mostly in developing countries
  • Multilateral organizations, many African organization that seek to solve water contamination
  • Sub-Saharan African Countries such as Angola, Burkina Faso, Ethiopia, Ghana, and Kenya

4)Deploying the technology (household level)

  1. Provide sustainable containers such as polyethylene terephthalate (PET) bottles or clear plastic bags 
  2. Place water and expose them to direct sunlight for 6 hours 
  3. Individuals, households, small communities, and refugee camps use clean water by removing bacteria and virus

*While this simple technology is more applicable to many african countries, community level utilize the enhanced CPC photoreactor to dispense treated water into a collection tank.


Edible water blob

1. Identify the problem

Humans are highly addicted to plastic products, and we are producing over 380 million tons of plastic every year. Plastic products are not biodegradable, and remain in the environment for a long time. 

In the case of bottled water, people drink bottled water everyday due to its convenience and portability. Those are made from crude oil, and pollutants such as nickel, ethylene oxide, and benzene are released during the production process. It pollutes air in the production process as well as the transportation process. 

2. Sustainable technology: Edible water blob

The edible water blob is a possible solution to replace plastic bottles, and it carries any liquid types such as fresh juices, sauce and beer. The material is cheaper than plastic and the biodegrade process takes only six weeks on average while plastic bottles require 450 and 1,000 years. Skipping Rocks Lab uses a technique called ‘spherification” to produce edible water bottles. This simple process mixes sodium alginate and calcium chloride until they get a gelatinous membrane that encapsulates water or any other liquid. Due to the relatively simple process, the lab manufacturing process is able to produce several thousands of edible water blobs in a single day. Seaweed grows rapidly and naturally degrades quickly while it does not compete with food crops. Therefore, using seaweed for materials to produce edible water blob makes their products highly sustainable. Edible water blobs do not impact the taste or color of the liquid inside as well. They are working on developing a machine to produce edible water blobs to expand their product worldwide. 

Article Source:,a%20group%20of%20design%20students


  • Shifting requires a box, and their concept of packageless and zero waste products does not match with the core concept of the idea. 
  • Difficult to communicate with consumers without using a printed paper-based label. 
  • Warning, ingredient information is obligated to be on the product’s packaging, and it really destroys the idea of this product. 
  • Transporting long distances may impact the product.

3. Identifying Stakeholders

  • All citizens of the planet
  • City officials looking to reduce plastic waste
  • Consumers who seeks sustainable products
  • Industry such as hotel or sports events that seeks to reduce plastic waste

4. Implementation 

  1. Secure a factory that can transform biodegradable seaweed and calcium chloride based edible membrane. 
  2. Produce edible water blob through a process called “spherification” (mix sodium alginate and calcium chloride and transform into a gelatinous membrane)
  3. Tie-up with various industries to create new products that can expand worldwide.

Bio-Latrine technology from Uganda

1) Many African countries like Uganda experience soil degradation, inadequate sanitation, and lack of access to clean energy. African farmers and rural area residents are one of the most vulnerable populations that do not have access to adequate sanitation facilities and are exposed to disease like diarrhea. 

2) A project engineer at Uganda acknowledged the challenges of soil degradation, inadequate sanitation and clean energy, and she came up with a bio-latrine. This environmentally friendly toilet utilizes biogas digester to convert human excrement into a quality agricultural fertilizer. While combustible gas is produced in the middle of the process, it is also used for cooking, heating and lighting. This technology addresses energy, sanitation, agricultural production all at once, which greatly enhance living standards in rural areas. This technology is placed in community centers, schools, churches, and hospitals. 

“African entrepreneurs lead the way in climate change adaptation” Dec/2016 

“Practical_action_bio_latrine” 09/2013

3) Stakeholders

  • People in rural areas mostly in Africa where adequate sanitation facilities do not exist. 
  • Cities officials who wants to solve energy, sanitation, agricultural production all at once

4) Three implementation steps

  1. The bio-latrine is low maintenance system that only need toilet and a bio-digester units 
  2. Construction can be done by using local materials only. 
  3. The minimum required materials are biogas digesters, biogas lamps and pressure gauges and stoves. It does not need machinery. The collected biogas will be transferred through underground pipes into stoves that households use. 

Problem and Challenges

It does not require water unlike sewage systems and flush toilets, so bio-latrine is great technology for places where water is scarce. However, there is a potential threat of leakaging of the pressured gas if the unit is not constructed well. Moreover, the high capital cost is a great burden for low income areas. Considering only the low-income areas are the potential customer for the technology at this moment, it is not sustainable in financial perspective. While human waste and biogas are converted into fertiliser and fuel for cooking, some populations might be reluctant to accept use of it. It is a critical issue whether there is a market for the fertiliser exist. 


Salt Water Desalination

1) While water covers the majority of our planet, freshwater scarcity is already a huge issue in many regions of the world. Arid areas particularly suffer for the most, and they have a lack of freshwater resources in the form of surface water. Underground water resources are turning into more brackish due to relentless extraction from the aquifers. We use freshwater to drink, bathe in, irrigate our farm fields, but only 3% of the total water is qualified as freshwater. Within 3% of the water, two-thirds of it is stored in frozen glaciers, so we only use the remaining one percent as freshwater. 

Approximately 1.1 billion people in the world lack access to water, and inadequate sanitation causes diseases such as cholera, typhoid fever, and other water-borne illnesses. Each year, two million people die from diarrheal diseases alone. Climate change alters patterns of weathers and water in the world, which led to shortage and droughts. Under the current trajectory, two-thirds of the world’s population is expected to face water shortage problems. 

2)  Desalination is considered as one of the possible solutions to provide sufficient water quantity and quality against population growth and climate change. Desalination refers to the water treatment process that converts sea or brackish water into potable water. Among various methods, Reverse Osmosis is the most advanced desalination system in the world that accounts for 60% of the world’s facilities. This technology uses a high pressure pump to dissolve salts up to 99%+ including colloids, organics, bacteria, and pyrogens. When high concentration salt water receives pressure, the water flows in a reverse direction through the semipermeable membrane and leaves the salt behind. In sume, it starts with a pre-treatment system and uses high-pressure pumps. Afterwards, it utilizes membrane systems and completes the process with post-treatment. 

Sustainability issues

The desalination process demands a huge amount of energy, and is very expensive. Depending on the location, labor and energy costs, monetizing the value of the process varies. Under the currency technology, it is more economical to purchase local freshwater. Moreover, sea life sometimes gets sucked into desalination plants. When the separated salt water is returned into the ocean, it also gives a negative impact on aquatic life. Minimizing the negative impact is possible, but it costs even more.

“Desalination of Water”, Manish Thimmaraju et al, 3/5/2018

“Why don’t we get our drinking water from the ocean by taking the salt out of seawater?”, Peter Gleick,7/23/2008,that%20separates%20salt%20from%20water.

3) Stakeholders

  • All citizens of the planet particularly in arid regions. 
  • Vulnerable population who are exposed to water related diseases
  • Energy companies like ACWA power that wants to combine renewable energy and desalination technology to create extra synergy

4) Three steps of deploying the technology

  • Takes the seawater through a semipermeable membrane 
  • Filters smaller particles through pretreatment filters. Remove salt from seawater through a high pressure through reverse osmosis membranes. 
  • Returns seawater to the water and store drinking water


Vertical Farming

As the world’s population is projected to grow, feeding people becomes one of the major challenges. However, arable lands are rapidly decreasing due to industrial development and urbanization. Vertical farming can be a way to solve the challenge, since it does not grow vegetables and other foods in a field or a greenhouse. It produces food vertically on structures like skyscrapers and shipping containers. Controlled Environment Agriculture (CEA) technology controls temperature, light, humidity, and gases artificially. The technology allows us to maximize crop production through metal reflectors and artificial lighting instead of solely relying on natural sunlight. 

How does the technology work?

Crops are cultivated in stacked layers in a vertical structure, and artificial light keeps the perfect light level in the room. Specialised technologies like rotating beds are also used to enhance the efficiency of the light as well as meeting the different crop requirements. Instead of using soil, vertical farming uses three different models. First of all, hydroponics allows crops to grow with the nutrient-rich water basin. It sustainably recirculates water to reduce water consumption. Drip irrigation, Nutrient film techniques, and deep water culture are used in the method. Second of all, aeroponic farming sprays crops with a nutrient-based mist. It does not require typical agricultural essentials such as soil, sunlight, or water, but it uses a periodic timer. This method allows plants to receive nutrients directly, and crops are easily harvested. Third of all, aquaponics cultivates fish and plants at the same time. It is a closed-loop food production system that provides nutrients and beneficial bacteria, and plants produce clean water for the fish. These productive methods also allow them to conserve water. 

Sustainability issues

Rainwater tanks, wind turbines, and multipurpose certainly offset energy costs in vertical farming. While it maximizes crop production, it consumes less water than conventional farming practice. In addition, it does not necessarily need the use of pesticides and herbicides that damages the environment. Since fresh food are sourced locally, it decreased the need of shipping. 

What You Should Know About vertical farming, Rick Leblanc,12/17/2020

A Beginner’s Guide to Vertical Farming, Claudia Beck 12/28/2017


  • All citizens of the planet
  • Government, local governments that wants to cut water consumption as well as reducing Co2 emission less than open field agriculture
  • Farmers who hopes to enhance their crop yields
  • Cities that heavily reliant on imported food

Steps for deploying the technology

Implementation of the technology varies based on the size. For larger-scale vertical farming that is capable of producing sufficient food for communities, investing in existing vertical farms or raising capital to build are the one of the options. Funding on research and development, renovation, waste integration system, and marketing campaigns are required for the success of the technology. In order to implement the technology, farm managers need to own a building or rent for a long term. Hydroponics systems are often required to maintain the desired indoor climate all year round. 

Byungchul Jeon/ Uni:bj2446