Technical Report No. 73
Bei-Jiann Chang, Reginald H. F. Young, James C. S. Chou
A study of the application of reverse oamosis technology to the treatment of Hawaiian low quality waters was conducted. The purpose of the study was to investigate the technical and economical feasibility of utilizing reverse osmosis technology to renovate waste waters after varying degrees of conventional treatment, and to desalt Hawaiian brackish groundwater from both basaltic and reef limestone aquifers.
The experimental investigation of the technical feasibility of renovating waste water and desalting brackish groundwater was conducted with a small reverse osmosis pilot unit at four test sites on the island of Oahu. The operation of the reverse osmosis pilot unit in processing waste waters suffered from the problem of performance decline. However, the pilot unit’s operation with brackish groundwater yielded promising results. In general, high rejections of total dissolved solids, refractory organics, nutrients, bacteria, and virus were accomplished by the unit.
Two waste water reclamation schemes incorporating the reverse osmosis process were considered possible in Hawaii. Treatment expenditures of the two schemes were estimated at 97.8 cents and 103.2 cents per 1000 gallons of treated waste water. Based on a cost model developed for estimating desalting costs by reverse osmosis plants with spiral wound modules, product water costs in Hawaii were estimated at 83.7 cents, 63.4 cents, and 49.7 cents per 1000 gallons for 1, 10, and 50 mgd plants, respectively.