DRINKING WATER PRODUCTION BY ULTRAFILTRATION FROM LOW-QUALITY INFLUENTS WITH OZONATION PRE-TREATMENT

Abstract

Despite the multiple advantages of membrane technology, ultrafiltration is not fully applied to drinking water production because of the two main drawbacks of the membranes: low retention of natural organic matter and fouling. Nevertheless, the application of pre-treatments can help to improve the membrane performance; thus, a study was carried out with ozonation prior to ultrafiltration for a fixed influent water quality. The experiments were carried out with real-scale spiral-wound membranes in a pilot plant located in Granada (Spain), for 1 m3/h flow rate and high humic-content influents (7.5 mg DOC/L). The main purpose was to compare the effluent quality achieved with and without pre-ozonation. In addition, doses between 5 and 25 g O3/Nm3 were tested to determine if the ozone concentration had any influence on the resulting effluent quality. However, the results showed the application of ozone at rates of 4.0 g/h maximum had very little influence on the reduction of the organic matter content. In fact, the application of the highest ozone doses barely improved the DOC removal efficiency achieved with direct ultrafiltration. These findings question the suitability of ozonation as pre-treatment for ultrafiltration applied to drinking water production and suggest other processes should be applied instead.