TOTAL TRIHALOMETHANE DISINFECTION BY-PRODUCT CONCENTRATIONS LEVELS OBSERVED IN DRINKING WATER FOR SOME LOCATIONS IN BAGHDAD CITY AND THE EFFECT OF ULTRAFILTRATION IN MINIMIZING THEM

摘要

In Jaderia-Baghdad drinking water treatment plant the Taiger river water is treated by using the conventional drinking water treatment process which is coagulation, flocculation, sedimentation, sand filtration and in the last stage disinfection using chlorine gas. The main purpose for drinking water treatment plants is to remove the organic, inorganic contaminants, colloidal and microorganisms such as viruses, bacteria and protozoans. However, recently researchers have found that this treatment may not enough because of soluble organic contaminants or natural organic matter (NOM), both of which could be a source for the formation of disinfection by-products when water is disinfected by chlorine. Hence, NOM removal is one of the most important treatment requirements for the production of good quality drinking water. The NOM reaction with chlorine gas generally forms halogenated compounds. These compounds for example trihalomethanes (THMs) and haloacetic acids (HAAs) are regulated in some countries. Recent studies identified new DBPs in disinfected drinking water by using most of chemicals employed for disinfection . Enhanced coagulation is one of the methods used to minimize the organic materials in treated drinking water plants. Also small particle size of granular activated carbon (GAC) can adsorb natural organic material (NOM) and this can be increased by acidification of raw water9. The ultrafiltration process using organic or inorganic membranes technology in water treatment plants has started to take its place in the world which prove their ability to minimize the organic material in the treated water. This is achieved by using ultrafiltration hollow fibre membranes or flat sheets in submerged systems that are situated inside tanks filled with the raw water to be filtered. The driving force in this process is carried out by vacuum on the permeate side created by suction side of a pump which is usually self-priming.