Design considerations for major membrane treatment facility for groundwater

The City of Boca Raton Florida will construct a 40 mgd nanofiltration plant in the coming year. This will be the largest plant of its kind in the world. This paper focuses on the design features of the plant and the results of

The results of pilot scale and bench scale testing reveal the following information for design of the new 40-mgd nanofiltration plant. 1. The membrane system at 85% recovery can operate without using acid to control W.B. Suratt et al. /Desalination carbonate scale and operation at a natural pH reduces membrane fouling caused by the dissolved humic acids. available antiscalants 2. Certain commercially and dispersants increase the rate of membrane fouling by humic acids. 3. It may be possible to operate without antisealants (or dispersants) at 85% recovery because of the natural antiscalant properties of the dissolved organics in the feedwater. 4. Nanofilters have different zeta potentials in the presence of the feedwater and also display 131 (2000) 37-46 differing tendencies to be fouled by the dissolved organics. Furthermore, the fouling tendencies increase at lower pH. 5. The hardness rejection of the membranes increased with time when treating the raw water. It is thought that the organics adsorbed increased hardness membrane by the rejection. The original hardness rejection is restored when the membranes are cleaned. 6. Zeta potential and electrophorectic measurements are a useful tool for screening membranes and antiscalants.