Pre-ammonization in the Preparation of Chromaticity Water for Drinking Purposes

Abstract

The natural water sources of the North-West region of Russia are characterized by low turbidity, medium and high chromaticity, the presence of organic and bacterial pollution, and an increased anthropogenic load. As part of the technological scheme for the purification of such water, disinfection with chlorine and its derivatives is used. When water is chlorinated, volatile organochlorine compounds are formed, such as trihalomethanes (chloroform, bromoform, bromodichloromethane, and others). Some of them are carcinogenic. The results of the correlation analysis, which showed that the formation of chloroform is influenced by the chromaticity (R2 = 0.24) and permanganate oxidizability (R2 = 0.43) of river water, as well as the dose of chlorine (R2 = 0.65). The article substantiates the use of preliminary ammonization using ammonium sulfate. The description of the experimental stand simulating the operation of an industrial waterworks and its operating modes is given. The experiments were carried out on real water with permanganate oxidizability of 10–11.8 mgO2 / l, chromaticity—59–76 deg., turbidity—4.5–4.7 EMF, pH from 7.4 to 7.6 and alkalinity of 4.6 mmol / dm3. Ammonium sulfate was dosed into water 1–2 min before chlorine. It was found that at doses of ammonium sulfate 0.3–0.6 mg / l and the ratio of ammonium to chlorine (1:4, 1:6, 1 8), chloroform is formed in minimal quantities, but its concentration does not exceed the hygienic standard. At the same time, the concentration of residual chlorine in the purified water was—0.94–1.18 mg/l.