Assessment of Water Treatment Technologies in Removal of Heavy Metals from Drinking Water Sources at Greater Cairo

Abstract

Water of high quality is essential to human life and water of acceptable quality is essential foragriculture, industrial, domestic and commercial uses. All these activities are also responsible for pollutingthe water. Billions of gallons of waste from all these sources are thrown to freshwater bodies every day. Therequirement for water is increasing while slowly all the water resources are becoming unfit for use due toimproper waste disposal. The task of providing proper treatment facility for all polluting sources is difficultand also expensive, hence there is pressing demand for innovative technologies which are low cost, requirelow maintenance and are energy efficient. The adsorption technique is economically favorable andtechnically easy to separate as the requirement of the control system.

Aluminum sulphate (alum) is a common coagulant chemical in the water treatment industry. As a result, the Water Treatment Plants (WTPs) that use this chemical is highly focused in aluminum. Aluminum is the third most abundant metal on earth, making up 8% of the earth’s crust. When aluminum becomes mobilized, it can have toxic effects on the aquatic species living in surface waters. For example, acid rain can increase aluminum in the waters by releasing aluminum normally bound in soils and rocks. Due to the recent acidification of waters systems many studies have investigated the toxicity of aluminum on aquatic ecosystem. The increase in aluminum inthe receiving waters and the toxic effects it can have on aquatic species has led the Canadian Council of Ministers of the Environment (CCME) to impose aluminum discharge guidelines.

Natural zeolites showing cation exchange properties have been recognized in sedimentarydeposits of volcanic origin for more than a century. Theunique physical and chemical properties of zeolites, their capability of undergoing cationexchange and reversible dehydration, and their open framework structures liable to act asmolecular sieves, render zeolite as a sedimentary deposit of commercial value. Due tothese factors and combined with their geographically widespread abundance, zeoliteminerals have generated world-wide interest for use in a broad range of applications suchas nuclear and municipal waste, water treatment, stack-gas clean-up, natural gaspurification, petroleum production, and in agriculture and aquaculture. Aim of the work General objective of the present studyis to verifythe quality of the drinking water that produced from surface water treatment works with different treatment technologies. To achieve this purpose, water samples have been collected from six water treatment plants in Greater Cairo. The samples were drawn from raw water source (inlet) and final treated water (outlet) at the water treatment works. The quality of drinking water was verified by: 1- Testing physical and chemical parameters. 2- Testing microbiological parameters including bacteriological examination and microscopic examination for biological parameters. 3- The results of testing were compared with the Egyptian standard for drinking water (Ministerial Decree No. 458, 2007) to evaluate the compliance with the regulations. In addition the results were compared with the WHO guidelines for drinking water.

Another specific objective has been set as bench scale experiment to determine the removal of aluminum from drinking water using natural adsorbent, zeolite.