A GIFT FROM THE UAE TO THE WORLD, A CARBON-NEGATIVE BIO DESALINATION PROCESS USING ALGAE

Dr. Aly Hassan Ashraf

Associate Professor, Department of Civil and Environmental Engineering

University

As the global population increases and resource-intensive economic development continues, many countries' water resources and infrastructure are failing to meet accelerating demand. Water scarcity will continue to increase at an alarming rate due to climate change globally.

Coastal areas are extremely affected by a lack of drinkable water because of limited freshwater availability, and an estimated 1.3 billion people will have no access to drinkable water by 2035. Thus, seawater treatment is the only viable option for coastal regions. Desalination using reverse osmosis (RO), multistage flash distillation (MSF), multi-effect distillation (MED), and thermal distillation are the most used technologies.

According to the United Nations, water scarcity affects more than 40% of the global population. This has prompted Associate Professor Ashraf Aly Hassan to develop and study how algae can be used to desalinate seawater, brackish water and produced wastewater.

The United Arab Emirates University researchers Dr. Ashraf Aly Hassan and his Ph.D. student Abdul Mannan Zafar, from the Department of Civil and Environmental Engineering, in their paper on “Seawater bio desalination treatment using Phormidium keutzingianum in attached growth-packed bed continuous flow stirred tank reactor” have developed the first of its kind process for bio desalination using carbon negative algae.

This study presents the utilization of the phormidium keutzingianum strain, algae in an attached growth-packed bed reactor to treat seawater in real-time in a continuousflow stirred tank reactor for bio desalination.

Dr. Ashraf Aly Hassan has been working in the field of environmental engineering, with assignments spanning North America, Europe, and the Middle East, allowing him to gain invaluable insights into diverse environmental challenges and their solutions.

His biggest passion has always revolved around sustainable approaches to air and water pollution reduction. He is passionate about utilizing cutting-edge technologies that are environment friendly and cost-effective.

In 2010, while he was in the USA receiving his post-doctoral fellowship at US EPA (Environmental Protection Agency) Cincinnati, Ohio studying air treatment and desalination and in his search for inspiration he stumbled upon an article that utilized algae treatment. As he explained, “At the end of the article the scholar mentioned that while implementing their research, they found that the salinity of the water also decreased. This intrigued me more than the rest of the paper.”

Upon further research, he found that in the 1980s a German scholar had written an article on how algae could alter the salinity of water, yet no other information could be found.

As a result, Dr. Aly Hassan applied for a grant from the EPA and received funding for the first proof of concept.

When he joined UAE University, the idea once again came back to the forefront especially because he realized that this was much needed in the Middle East and GCC region.

On receiving the startup grant from the university, the bio desalination journey began.

Bio desalination using algae in a negative carbon process

According to Dr. Aly Hassan, while the journey started in a lab, the latest research was the first proof of concept carried outside in the scorching heat of the region and bright daylight. For the first time, real daylight was used instead of artificial light, and real seawater was used.

The researchers were able to decrease the salinity of the water by 45% while enhancing energy efficiencies thus reducing cost. As Dr. Aly Hassan explains, “It has been a journey from lab to real-world proof of concept and we have done very well. Not only have we been able to decrease salinity to a point where the water is drinkable, but we have done this using a negative carbon process.”

Carbon negative means that you emit less than zero carbon dioxide and carbon dioxide equivalent (CO2e) greenhouse gasses. However, since it is impossible to emit a negative amount of carbon (or any other physical substance), being carbon-negative refers to the net emissions you create. To be carbon negative means to offset more carbon, through carbon capture, sequestration, or avoidance, than you contribute to the environment.

He explains, “Our process is energy efficient and uptakes carbon. Carbon uptake is the process by which the oceans (or plants and forests) absorb carbon. Algae absorb carbon when they are growing, so while we might use some energy to pump the water into the reactors, we are negative CO2 because the alga updates CO2 in the total process.”

According to Dr. Aly Hassan, this was the very first trial in real conditions and much was learned about how the algae handle the heat in the UAE finding that algae-covered reactors performed better than uncovered for example.

He adds, “With our trials, we are perfecting desalination in shorter time periods. It is more important to be faster because it means you can be economical in terms of water treatment. The goal is to achieve the same efficiency in less time, and we have achieved this.”

Currently, the researchers are preparing a manuscript on the feasibility and economic gains. As Dr. Aly Hassan explains, “Here four scenarios are under review, the completely traditional methodology of desalination, our system followed by reverse osmosis, our system in two different setups, and in all these scenarios our process is more energy efficient and much more cost-efficient.”

What can the algae desalinated water be used for?

Desalinated water using algae can be used in several ways. For example, algae desalination combined with reverse osmosis can create drinking water; without reverse osmosis the algae-treated water can be re-injected into the groundwater decreasing the overall salinity as well as less nitrogen and phosphorous. According to Dr. Aly Hassan, this is important for ensuring sustainability to future generations.

The algae-desalinated water can be also used for irrigation as algae treatment could drop the salinity down below 10 grams per liter making it possible for some types of irrigation. By going through the reactors in two or three cycles followed with reverse osmosis, the water becomes possible to drink as well. As Dr. Aly Hassan explains, “Current desalination entities can use our technology in the pre-treatment phase allowing them to decrease cost, energy consumption, and CO2 emissions in the process.”

This is significant because the current process of desalination using reverse osmosis (RO), multistage flash distillation (MSF), and multi-effect distillation (MED are highly energy-intensive and require significant chemical additions, which increases the operational expenditure (OPEX) of the desalination plant. An average RO desalination plant consumes 1.2–10 kWh/m3 of electricity to desalinate seawater and the cost of treated drinkable water has increased owing to extensive energy-intensive water treatment processes.

Therefore, innovative low-energy-consumption and natural seawater treatment options are urgently required. These strategies reduce the energy consumption load and eventually the carbon footprint in response to low-energydemand technologies. Bio desalination requires low energy for operation, which makes the technique highly energy efficient. Algal and cyanobacterial desalination requires fewer chemicals and operational elements than other seawater desalination techniques, and different techniques are available to grow these microorganisms in seawater and brackish water.

In addition, the brine that is produced out of reverse osmosis is very highly concentrated with salt. It usually needs to be diluted before it is sent back into the sea which in the long term is not environmentally friendly. However, with bio desalination, the algae itself absorbs the brine salt turning it into a biofuel source. Dr. Aly Hassan states, “Since the 1970s algae have been seen as a green energy source, and by utilizing the algae saturated in brine salt for energy we are not throwing anything away. This is the big picture. Biofuel is the way to go.”

So, the algae being used for bio desalination will then be utilized as green energy given it is a biofuel. Studies have shown that the higher salt levels in algae the more biofuel is produced.

The future of bio desalination research project

The proof of concept implemented by Dr. Aly Hassan and the research team is moving towards a prototype version on a big scale.

For the first time, cyanobacteria which is toxic and if it is available in huge amounts in wastewater and seawater can kill all living organisms is now being put to even better use.

The researchers have utilized different approaches using indigenous algae adapted in the lab making sure it can grow in UAE waters.

In other tests, Dr. Aly Hassan and his team were able to desalinate and clean one of the most toxic waters, that of water extracted from oil and gas wells. As Dr. Aly Hassan explains,” This water is even more salty and full of heavy metals, the most dangerous type of wastewater ever. Yet we managed to adapt an alga that wouldn’t die in this toxic wastewater and were able to achieve desalination as well as extraction of metals to the point where this water could be used for irrigation or put back into the wells.”

Even though the treatment will need reverse osmosis, before this breakthrough even with reverse osmosis you couldn’t re-inject it into groundwater or well because it was still extremely polluted.

Bio desalination and the road to Sustainability

The importance of desalination is paramount, and Dr. Aly

Hassan believes that by 2030 bio desalination using algae will be part of any desalination project as the world cannot continue to do what it is doing today.

He gives the example of the latest desalination plant in Dubai which had a groundbreaking cost of just 0.36 cents per cubic meter, yet this is still very expensive according to him. The proof of concept has proven that bio desalination using algae costs much less and saves the environment in the process.

As he concludes, “My passion has always been the safer/ better environment; and this is what guided the research.”

Title of Published Paper:

Biodesalination and treatment of raw hypersaline produced water samples using indigenous wastewater algal consortia

Published in: Desalination

The Impact Factor: Desalination is 11.211

It is published by Elsevier BV

The journal is indexed in UGC CARE, Scopus, SCIE

The (SJR) SCImago Journal Rank is 1.471.