AWWA MTC95023

Iron mine drainage water is used in Lorraine in east France, as a source of drinking water for 300,000 people. The closing and flooding of the mines has resulted in a significant degradation of raw water quality. The important increase in sulfates in water from 100-200 mg/l to 500-1,000 mg/l is due to the oxidation of the pyrites (FeS2). Moreover, it is accompanied by a rise in hardness. The sulfate level exceeds the Maximum Admissible Concentration (MAC) of 250 mg/l making the water unsuitable for consumption according to French and European standards. Nanofiltration is the only process allowing simultaneous softening and sulfates removal. Pilot studies demonstrated the feasibility of this process to remove 90 to 95% of sulfates and hardness. The results of the tests using a 100 m3/d (26,420 gpd) unit equipped with three stages of spiral-composite modules are presented. It is shown that process recovery should be limited to 75% to prevent calcium sulfate scaling. The results obtained have led to the design and construction of two plants with a capacity of 2,500 m3/d (0.66 mgd) each. These plants were commissioned early in 1995. The full-scale plant is described and the start-up results are discussed.

Product Details

Published:

01/01/1995

ISBN(s):

0898678153

Number of Pages:

10

File Size:

1 file , 350 KB