Optimal use of Nanofiltration for Nitrate Removal from Gaza Strip Municipal Wells

Abstract

Due to excessive usage of nitrate fertilizer in agriculture and discharging of wastewater from treatment plants, and leakage of wastewater form cesspools, nitrate level of water resources are increased. Increased nitrate in water resources could lead to serious problem including eutrophication, and potential hazards for human and animal health. The aim of this study is to optimize the use of Nanofltraiton for nitrate removal in Gaza Strip as case study. One commercial membrane (NF90) was used in this study. The stirred dead end flow model was used in addition, two types of water was used: Aqueous solution and real water. The performance of the tested membrane was measured in terms of flux rate and nitrate rejection under different operation conditions: nitrate concentration was varied between 50-400mg/L, applied pressure (6-12) bar and TDS concentration (500-3570) mg/l. The percentage of nitrate removal in real water was in the range of 0.52% and 55.63% and the flux rate range between 2.61 and 30.12 L/m2.hr. These values depend on operation conditions such as nitrate concentration, TDS composition and operation pressure. In real water, the percentage of nitrate removal was influenced by TDS value in general, but to be more specific, it was found that the concentration of sulphat has a great effect on nitrate removal, as the sulphat concentration increased the nitrate removal decreased. The optimum operating pressures are 8.6, 11.6 and 10.8 bar at H104, E142A and D75 well. Which achieve Palestine standard (70 mg/L) and high flux rate 7.46, 26.66 and 8.74 L/m2.hr. NF90 was observed to be an effective membrane for nitrate removal of Gaza Strip at higher permeate flux and lower applied pressure, especially in North Gaza Strip were low TDS and Sulphat concentration were observed. Keywords: NF90, Nitrate, Rejection, Well, Total dissolved solids and Pressure.