Pretreatment approach for the high turbid seawater using decanter centrifuge-microfiltration hybrid system

The quality of seawater is different at different locations in Kuwait. The seawater quality in the Sabiya Power Generation and Water Desalination Plant (SPDP) is highly turbid due to the high silt and sand content and this often results in major disruptions to the plant’s operations and requires frequent unscheduled maintenance. In spite of the availability of the space required for the installation of additional desalination and power generation units within the Plant, the seawater quality at that location limits full use of such units. This study aimed at assessing the viability of enhancing seawater quality for thermal and membrane-based desalination processes at SPDP using an integrated pilot-scale decanter centrifuge/microfiltration (MF) system. The study concluded that (1) polyelectrolyte dosing along with clarifier tanks placed before the decanter centrifuge unit were very effective in stabilizing the quality of the seawater feed; (2) the decanter centrifuge system is a viable mechanical process for improving the quality of SPDP’s seawater feed; (3) the efficiency of the decanter unit reached 99.6%; (4) the turbidity values obtained immediately after the decanter unit were lower than 5 NTU, however, it was very difficult to obtain silt density index (SDI) measures below 6; (5) conversely, SDI values lower than 3.5 were achieved with further treatment utilizing MF system which is an acceptable level that facilitates safe use of the seawater as feed for membrane and thermal desalination units as well as for power generation equipment.