Development of Low Cost Membrane Cleaning Agents.

摘要

The study included a laboratory phase and a field-test phase. In the laboratory phase using either a synthetic water or Wellton-Mohawk canal water,scales were deposited on cellulose acetate RO membranes. Cleaning tests were performed with various chemicals and combinations of chemicals. For gypsum scales, a combination of EDTA,ammonium bicarbonate and a fluorocarbon surfactant was found to be more effective than EDTA alone,or any other formulation tested. Ammonium bifluoride was found to be best for SiO2scales,whereas sodium hydrosulfite was best for iron-containing scales. Experiments were also run on the effectiveness of several commercially available scale inhibitors for the inhibition of calcium carbonate and gypsum scales. These results showed that products'marketed by Monsanto and Aquaness were most effective for the inhibition of calcite and gypsum,respectively. The field-test portion of the program showed that the predominant scale deposit obtained was a clay-like material composed of Si,Al,Ca,Mg and Fe. These deposits are extremely difficult to remove and were only partially removed by some of the better performing cleaners tested in the laboratory.