ABSTRACT
Various bacterial growth potential (BGP) methods have been developed recently with the aim of monitoring biofouling in seawater reverse osmosis (SWRO) systems such as assimilable organic carbon and bacterial regrowth potential. However, the relationship between these methods and biofouling in full-scale SWRO desalination plants has not yet been demonstrated. In this chapter, a new method to measure bacterial growth potential (BGP) in seawater using indigenous microbial culture has been developed based on microbial ATP. Moreover, an attempt is made to investigate the correlation between BGP of SWRO feed water and the chemical cleaning frequency in three SWRO plants using the newly ATP-based BGP method.
The detection limit of BGP is investigated to 13 µg glucose/L). Low variations of bacterial yield were observed for five different seawater locations. BGP was monitored in raw seawater of North Sea and seasonal variations is observed ranging between 45 µg-glucose-C/L in the winter and 385 µg-glucose-C/L in the autumn.
The BGP method was applied to assess the pre-treatment performance of three full-scale SWRO plants with different pre-treatment processes. Dual media filtration (DMF) showed the highest BGP removal (> 50 %) in two SWRO plants. Removal of BGP and hydrophilic organic carbon in dissolved air floatation combined with ultrafiltration was similar to the removal achieved with DMF in combination with inline coagulation. For 78the three SWRO plants investigated, a higher BGP in the SWRO feed water corresponded to a higher chemical cleaning frequency. However, more data is required to confirm if a real correlation exists between BGP and biofouling in SWRO plants.
