Table 3.

The summary of the experimental protocol using pilot-scale GE Osmonics E2-2535TM system.

No	Step	Operation	Justification
1	System checking and cleaning	The tightness of all tubing connections was checked. The system was cleaned with DI water.	To ensure components are well connected and the system is clean
2	System start-up	First the booster pump; then the high-pressure pump was started to pump the feed water through the membrane modules.	To start the filtration experiment with the groundwater sample
3	Operating pressure setting	The pressure was adjusted for operating pressure experiments with the concentrate valve to vary from 10 to 15 bar. For pH experiments, it was kept at 10 bar. Permeate and concentrate were recirculated.	To investigate the effect of operating pressure and pH of samples on Sr and TOC removal by NF/RO. Filtration was performed until a steady state was reached.
4	Samples collecting	The permeate samples were collected after the steady-state was reached.	To measure the Sr and TOC concentration
5	System cleaning	2% citric acid and DI water (conductivity < 1 μs/cm) were used for system cleaning.	To remove any accumulated foulants or scalants from the membrane surface and restore system performance