The purpose of this study was to evaluate the effect of unique water supply and demand flow conditions of a developing country with limited water supply and heavy water demand on corrosion, and subsequently on heavy metal leaching, and water quality at the user end. Bench scale reactors were setup to study corrosion of zinc coated iron i.e. galvanized iron subjected to three types of water (distilled water vs. natural organic matter vs. distilled water with humic acid), three different doses of disinfectant (0.2 ppm, 2 ppm, and 10 ppm), and two different water draw cycles. The corrosion influencing factors, including natural organic matter, disinfectant dosage were varied to investigate the differential in corrosion pattern and extent. Fill and draw cycle replicated the demand curve of an Indian city with demand peaking twice a day with gravity based intermittent supply. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy were used to analyze micro-morphology and chemical composition of corroded coupons. Inductively coupled plasma-optical emission spectroscopy was used to quantify heavy metals. Additionally, fourier transform infrared spectroscopy was utilized to profile the compounds formed in the water. Changes in water quality were monitored by determination of parameters such as pH, conductivity, turbidity, total organic carbon, and total nitrogen. Results show that distilled water with humic acid had higher levels of heavy metals and unique micro-morphology and chemistry of corrosion. The different experimental conditions demonstrated differential in physical (color, turbidity and conductivity) and chemical characteristics of water. The most abundant heavy metals found were iron, zinc, copper and lead, which were released from pipe material. Overall, results indicated that the synergistic effect of physicochemical parameters of water, pipe materials and water supply-demand curves were major drivers of corrosion and subsequent release of heavy metals.

Addressing contributory factors in the dissolution of heavy metals from zinc coated iron water supply pipes with flow conditions typical of developing countries

256th National Meeting (2018)

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