Performance feasibility study of direct contact membrane distillation systems in the treatment of seawater and oilfield-produced brine: the effect of hot- and cold-channel depth.

Membrane distillation (MD) is a technology that is emerging as a viable alternative to traditional desalination techniques. This study assessed the feasibility of using the direct contact membrane distillation (DCMD) configuration of MD to desalinate saline water of different concentrations. We considered the feed supply of Arabian Gulf seawater (AGS) sand oil field-produced water and used polypropylene (PP) and polyvinylidene fluoride (PVDF) membranes to consider their performance under different operating conditions, such as channel depth, flow rate, temperature, feed concentration, etc. Their performance was evaluated by determining the water flux relative to the volume of salt rejection. The results showed that the permeate flux increased to 32.4 from 10.1 L/m²·h when the temperature was raised from 45°C to 75°C. Additionally, the permeate flux decreased to13.6 from 27.3 L/m²·h and the reduction in flux was around fifty percent when the concentration of sodium chloride (NaCl) in the feed solution was increased to 26% from 0%. The experimental results obtained using oil field-produced water were highly encouraging. The permeate flux was 11.5 and 12.5 L/m²·h at 80°C and 85°C, respectively. The results indicated the enormous potential of DCMD to treat hypersaline oil field-produced water, with an overall rejection of salts reaching above 99%. In comparison, PP membranes had a higher salt rejection rate but lower water flux, while PVDF membranes had a lower salt rejection rate but higher water flux. This paper presents, for the first time, the results of a laboratory-scale study conducted in the State of Kuwait to treat AGS and oil-produced water using DCMD technology under Kuwait's prevailing conditions. This study's findings will lay the groundwork for conducting pilot-scale studies on AGS and oil-produced water not only in the Middle East region but globally. [ABSTRACT FROM AUTHOR]