Filtralite® at Beni Saf desalination plant: increasing production capacity and lowering OPEX
The Beni Saf desalination plant, in Algeria, is owned by the Beni Saf Water Company (BWC), and was built and is operated by Tedagua (Grupo Cobra). This plant is part of a large program undertaken by the Algerian government to provide the country with a stable source of drinking water, it produces 200,000 m3/day and is one of the largest water desalination plants in the Mediterranean.
In recent years, the Algerian coastal area has recorded frequent phenomena of concentrated rainfall, generating a high level of suspended solids, mainly of mineral origin, in the catchment bay of the Beni Saf desalination plant. This situation creates bottlenecks in production and increased operating costs.
To improve the situation, while minimizing investment, it was decided to replace the sand of the first filtration stage, 48 filters, by Filtralite® filter media, made of expanded clay. The first objective was to minimize rack downtime in times of high SS, and collaterally optimize operating costs, by reducing backwashing, improving quality and reducing pressure drop in filtration.
The works were planned in two phases: 24 filters in October 2020, and the rest in October 2021. The first replacement in 2020 allowed for a side-by-side comparison of Filtralite® versus sand. Between November 2020 and February 2021, when intense rain events happened, the average cycle with Filtralite® lasted 200% longer than with sand. In addition, the maturation period for the filters with Filtralite® was reduced by almost 66% compared to sand.
Production losses for the same period, November 2019 to February 2020, were compared with those suffered in 2020-2021 with Filtralite installed on 24 filters. Losses went from 673,000 m3, from the period to 2019-2020, to 380,000 m3: a 45% reduction. With the replacement of the other 24 filters, it is expected –based on the 2020 data– that the reduction due to stops will be above 85%.
During this period, there was also an improvement in the average quality of the filtered water of between 0.3 and 0.5 SDI points with respect to the data for the same period of the previous year. This improvement translated into a reduction in the frequency of replacement of cartridge filters.
Replacement of sand by Filtralite®, in addition to being a very competitive scenario, has shown to reduce productions losses due to frequent backwash, decrease water wasted for backwash and drop operating costs – energy, cartridges, chemical cleaning, O&M.