The results of instrumental studies for water pollution in many water bodies, and in the Tolich river — the principal river of Hanoi, capital of Vietnam — have been presented. The main part of pollution comes to water bodies through the city’s drain network, and directly through the urban areas’ relief. The data on devices and methods for assessment of quantitative and qualitative composition of Tolich river’s water has been presented. The main dangerous sources of river’s pollution are biological oxygen demand (more than 2.79 MPC), chemical oxygen demand (more than 3.29 MPC), ammonium nitrogen (more than 50 MPC), petroleum products (more than 20 MPC), phosphates (up to 10 MPC), and other substances. Has been presented data on quantitative composition of pollution from different branches of industry. Has been drawn a conclusion of need to create and carry out the State monitoring of water environment and coastal zones, and to introduce systems for artificial water aeration in water bodies to improve water’s self-cleaning ability.

Abstract. Ion-exchange softening plants wash water treatment studies are provided in order to bring them back to the process. Poorly soluble Ca and Mg compounds formation conditions have been studied during the course of such water caustic treatment using the potentiometric titration method. Information has been provided about the Ca and Mg hydroxide sludge sorption properties with regard to the characteristic contaminants of the sewage water generated by the textile industry enterprise. Suitability of the hydroxide sludge has been established for use in the sewage water treatment technology in order to remove the persisting organic compounds, such as the synthetic dyes.