Energy saving and optimising operating costs in desalination with Filtralite®
Algeria, like other countries around the world, is facing increasing problems in managing its water resources. The country already has 14 seawater desalination plants, with a further 5 under construction. In order to cope with this new technology, which requires specific skills, the country is also launching a training and scientific research program in 4 of the country's universities.
The 5 new, larger plants currently under construction will increase the amount of desalinated water produced by Algeria from 17% to 42%. They will, also, make more water available for agriculture.
The water situation in Algeria is characterised by major challenges. The country, located in an arid and semi-arid region, faces limited water resources and frequent drought conditions.
In Algeria, water availability per person is relatively low, which poses challenges not only for drinking water supply but also for agricultural irrigation and industry. Water resources used to come mainly from rainfall, groundwater, and dams. However, rainfall is irregular and groundwater recharge is limited.
In response, the Algerian government has introduced policies and programmes to improve water management, such as the construction of new dams and the expansion of drip irrigation. Yet problems of access to quality drinking water remain a reality for some rural and remote regions.
It is in this climate of widespread scarcity of water resources that Algeria is raising awareness of the need to conserve water, while at the same time looking for new outlets. Desalination is therefore part of this development strategy chosen by the government. Desalination plants play an essential role in diversifying sources of drinking water in Algeria, particularly in coastal areas where fresh water is scarce. They help to improve drinking water supplies for local populations.
In Algeria, water availability per person is relatively low, which poses challenges for drinking water supply, irrigation and industry
Desalinating seawater requires major investment in terms of infrastructure and energy. It is against this backdrop that the solution offered by Filtralite® filter media is an interesting one for reducing the amount of water taken from the environment and the cost of running the plant.
We had the opportunity to interview Mr Mohamed Chaffi, Director of the Beni Saf desalination plant. This plant can produce up to 200,000 m3/day. It belongs to the Beni Saf Water Company and is operated by Tedagua. It is one of the largest water desalination plants in the Mediterranean.
Filtralite® was implemented in the plant in two stages: 24 filters in October 2020 and the rest in October 2021. The first replacement in 2020 enabled a comparison of filters with Filtralite® versus sand.
Desalination plants play an essential role in diversifying sources of drinking water in Algeria, particularly in coastal areas
In recent years, Algeria's coastal zone has experienced frequent episodes of high rainfall, resulting in high levels of suspended matter in the raw water. This suspended matter is mainly of mineral origin and is causing difficulties in the production of drinking water and an increase in operating costs.
To improve the situation, while minimising investment, the sand in the first filtration stage, 48 filters, was replaced with Filtralite®. The primary objective was to reduce rack downtime when TSS levels are high and to optimise operating costs by reducing the frequency of backwashing. In addition, this change of media improved the quality of the filtered water and reduced pressure drops.
Production losses for the same period, from November 2019 to February 2020, have been compared with those for 2020-2021. Production losses fell from 673,000 m3 to 380,000 m3: a reduction of 45%. With the replacement of the remaining 24 filters, it is expected - based on 2020 data - that the reduction in production losses will be 85%.
As well as being a highly competitive scenario, replacing sand with Filtralite® reduces production losses due to frequent backwashing, cuts the water needed for backwashing, and optimises operating costs - energy, cartridges, chemical cleaning, O&M.
Read what Mr Chaffi has to say about using St Gobain's Filtralite® solution.
Can you present your career, your current role, and your degree of involvement in the Beni Saf project?
Replacing sand with Filtralite® reduces production losses, cuts the water needed for backwashing, and optimises operating costs
Mr Chaffi Mohamed, General Manager of Benisaf Water Company Spa, a joint venture between Grupo ACS and AEC Spa. I am an engineer in urban hydraulics and I have been working in the seawater desalination sector since 2008. As General Manager of BWC Spa since 2014, I have participated in several improvements in the plant including the change of the filtration sand by Filtralite®.
Can you give us a few figures on the characteristics of your plant? What solutions did you have for the filtration stage before the installation of Filtralite®?
The Beni Saf seawater desalination plant has been in operation since 2010 and has produced a total of 830 million cubic metres as of 31 December 2022. Prior to the installation of Filtralite®, the plant's process used filter sand.
How did you hear about the Filtralite® solution? What made you decide to take the plunge into this innovative filtering media? What barriers did you eventually encounter during this project?
I learned about Filtralite® during a professional event with Baptiste Rogeau at WEX Lisbon 2016. The characteristics of the product and the advantages offered attracted my interest in this product. At that time, I found a barrier regarding the product's marketing certificate as it was not yet used in seawater desalination plants, but on the other hand the advantages were numerous. So, we decided to invest in the Filtralite® filter media and certainly no regrets.
What problems justified the choice of Filtralite® media? Were you able to solve these problems with Filtralite®?
The problem encountered in the pre-treatment of the plant is the suspended solids (SS) which are limited by the process to 25 mg/l which obliges us to stop the plant to secure the equipment. We were able to partially solve this problem by increasing the SS limit to 40 mg/l with Filtralite® corresponding to a more than 62.5% increase on our rates.
Were you able to discover any unexpected results, positive or otherwise?
The results are positive because, since the installation of the Filtralite®, we have far exceeded this initial process limit. We have even continued to produce, partially, with SS reaching a level of 70 mg/l in 2022.
The amount of energy saved in the pre-treatment area is estimated at around 10%. It is thousands of dollars we can save every year
How would you describe the main aspects of Filtralite® and its advantages over your original solution?
The main aspects of Filtralite® are:
- Reduction of washing sequences
- Operation with SS above 25 mg/l
- Energy saving
Do you have any idea how much energy you are saving with the Filtralite® solution? What would be your estimated return on investment? Could you give us more details on this calculation?
The amount of energy saved in the pre-treatment area is estimated at around 10%. It is thousands of dollars we can save every year. Our estimated return on investment is 4 years due to the increase in the SS limit.
If you had to do it all over again, would you choose the Filtralite® solution? Would you recommend it to your colleagues?
Yes, I would do it again with pleasure. I have already recommended it to other stations.
What are the next projects in your factory?
Our next projects are the certification of our integrated system with the ISO 9001/ISO 45001/IS0 14001/ISO 50001 standards, the installation of 11 variable speed drives, and the installation of solar panels on all the factory's roofs to produce 1.5 MWp.