TRSA was contracted the balance of plant EPC to build a CCGT Power Generation Plant 1800 MW. The final end-user is Sharjah Eletricity and Water Authority (SEWA) whereas the Owner, Sharjah Hamriyah Independent Power Co. (SHIPCO), is an IPP company by Sumitomo, GE, Shikoku Electric Power Co. and Sharjah Asset Management (SAM), a subsidiary of the Sharjah government.
Due to the lack of fresh water the Plant includes a 7 ML/d capacity SWRO Desalination Plant with a pretreatment made by Coarse and Fine screening, Coagulation-flocculation, DAF flotation and DMFs, Cartridge filters and RO membranes.
SIGMADAF provided the pre-treatment of the SWRO plant complete with coagulation-flocculation tanks and two DAF units Mod. FPHF-350 for the removal of TSS and Algae in the seawater found during bad weather conditions or HAB episodes, to avoid the clogging of the DMF filters and the shut-down of the RO section due to lack of pretreatment capacity with consequential loss of feedwater supply to the power generation plant.
Nº of units
GRP (TANK) / SDSS (EQUIPMENT)
1 x 35 m3
2 x 35 m3 per DAF
TSS in / out
50 / 10 ppm
Turbidity in / out
15 / 5 ntu
Algae in / out
100,000 / 2,000 Cells/L (Efficiency 98%)
SIGMADAF order included the design and supply of the pre-treatment DAF package, with coagulation-flocculation, including pipes, valves, access ladders and platform.
The technology for the DAF is PACK LAMELAR with counter and crossflow to optimize the water flow distribution in the tank and facilitate the uniform water outlet from the side along the tank length
The physic-chemical treatment prior to the DAF is done in 1 coagulation tank of volumen 35 m3 (Ø3.5 x L 6.5 m) and 4 flocculation tanks (2 per DAF unit) of same unitary dimensions, designed for retention time of 2.5 and 20 min respectively. The tanks are constructed in GRP and provided with vertical mechanical multi-blade type mixers in SDSS (SAF2507).
SIGMADAF FPHF Equipment Features
The FPHF is a compact equipment especially effective for high water flow rates and high suspended solids content, using inclined lamella pack ot plates settler (IPS) technology. The FPHF equipment utilises a combination of cross flow and counter-current flow, the heavier settling particles are separated with a relative high efficiency in the lamellas by the FPHF.
High flows demand a better flow distribution in the flotation tank. The inflow surface of the lamella packs is equally divided against laminar flow proportionality within the system. In practice, it shows an attainable volume treatment above 100%, compared to conventional plate separators, which have mostly an overflow rate of at least 3 m/h.
In this project the FPHF equipment is expected to remove high TSS and algae under HAB episodes. The suspended solids are aggregated in flocs in the flocculation tank, but as they do not possess sufficient buoyancy to float, air-bubbles enhance the buoyancy separation process. The use of micro-bubble flotation technology (30 to 50-micron range) increases the float efficiency, as smaller bubbles easily adhere to equal-sized or larger particles, boosting the overall effectiveness of the system. The SIGMADAF air aerator generates the required amount of air to be injected in small size bubbles in quantity and well distributed in the full tank volume.
Unique system characteristics
The FPHF is a high-performance system with a number of distinct features.
• Efficient laminar water flow distribution, enhanced by the lamella pack and lateral pipe outlets along the tank length with adjustable outlet weirs to control the flow rates.
• Skimer with a single movement separator, which rotates against the hydraulic flow of the water, helping to minimise the distance of the floated sludge and eliminating solids carry-over. Floated sludge is extracted into a collection hoper with a DS content 3 to 4 times greater than a conventional system. Dewatering or drying costs are then minimized.
• Settled solids in the tank bottom are collected in the extraction auger with a shaftless screw device. The build-up and thickness of the solids is controlled with the operation time of the extraction screw and the pneumatic valve. The discharge cycle is self-cleaning and any particles adhered to the walls or sides of the system will loosen and follow their initial flow path.