AWWA ACE94014

The major difference between two reverse osmosis plants described in this paper are the well water quality and the finished water quality goals. The prison used a shallow aquifer with a well water having a lower TDS and had finished water goals which were not as demanding as the River's Edge Plant. These two factors allowed the use of a higher by-pass blend rate, which tends to reduce the unit cost of water. Both plants had a similar total annual operating cost, but the prison had a higher annual production due to the blending and, thus, had a lower unit cost. A third scenario for a plant of this type would be to use a softening membrane at a pressure of 100 psi. This type of membrane would be adequate to soften the water, remove THM precursors, reduce the TDS, and remove all color. However, the blend rate would have to be lower since the TDS and hardness would not be as low as a medium pressure RO system like the two plants described above. But with the lower pressure, the unit costs should be comparable to the prison's system described above. Also, with a lower blend by-pass, there is better control over THM precursors since more raw water passes through the membrane. Membranes are well suited for small systems because they are skid-mounted, fully automatic, and require less operator attention than lime softening or coagulation/filtration plants. The membrane plants also offer better quality water. Membranes will remove Giardia, Cryptosporidium, radionuclides, sulfates, nitrates, metals, and most organic pesticides.

Product Details

Published:

01/01/1994

ISBN(s):

0898677726

Number of Pages:

14

File Size:

1 file , 320 KB