Integrated technology for conditioning low-mineralized cold ground water

Summary

An advanced integrated technology for conditioning low-mineralized cold groundwater is presented. The technology was developed for the purpose of supplying drinking water to the oil and gas-bearing regions of the Tyumen North. With a favorable ratio of fresh water resources and the actual volume of water consumption in this region of Russia, the issue of drinking water supply from underground aquifers remains acute due to the problematic water quality and low efficiency of the treatment facilities. The technology is intended for removing iron, manganese, hydrogen sulfide and providing for the stabilization treatment of water. The main work including laboratory studies and pilot tests was carried out in the period 2001–2020. On the basis of the developed process solutions, water treatment facilities have been built and successfully operated in the cities of Noyabrsk (75 thousand m³/day, 2006) and Novy Urengoy (65 thousand m³/day, 2007). Additional tests of the technology carried out in Khanty-Mansiisk and Komsomolsk-on-Amur confirmed its effectiveness. The technology involves using hydrogen peroxide and potassium permanganate as the basic chemicals for the oxidation of water pollutants, as well as using an alkaline chemical for pH adjustment and stabilization treatment. To meet the requirements of the WHO standard for the concentrations of iron and manganese, an additional flocculant can be used. The data on the composition of groundwater used for testing are summarized, and on their basis the recommended area of application of the developed technology is determined. The basic process flow scheme of conditioning low-mineralized cold groundwater in view of 15 years of experience in operating the existing facilities, and of advanced solutions for dosing and mixing of chemicals, is presented. It is indicated that the technology also provides for a partial reduction in the silicon concentration in purified water (up to 30%). The developed technology ensures stable drinking water with a standard residual concentration of iron, manganese and hydrogen sulfide.

Key words

deferrization , hydrogen peroxide , ground water , potassium permanganate , demanganization , stabilization treatment , caustic soda , hydrogen sulfide removal

The use of hydrogen peroxide as a chemical in drinking water supply

Summary

The use of hydrogen peroxide for the removal of iron and hydrogen sulfide from natural groundwater is considered in the context of the recommendations of the new edition of CP 31.13330.2021 «SNiP 2.04.02-84*. Water supply. External networks and structures». A brief overview of the available data on the chemical regularities of the iron and hydrogen sulfide oxidation processes, and the factors affecting their behavior is provided. Based on data of the field tests, as well as on the experience of long-term operation of the water treatment facilities in the cities of Novy Urengoy and Noyabrsk, a formula is proposed for calculating the dose of hydrogen peroxide while removing iron from natural groundwater. Recommendations are given for estimating the demand for this oxidizer while removing hydrogen sulfide from natural groundwater. This technology provides for the drinking water of standard quality. The conclusion is drawn that the use of hydrogen peroxide as a chemical is promising for drinking water supply owing to its working efficiency at low pH values, alkalinity, water temperature; process independence from the silicon, carbon dioxide, oxygen concentrations, as well as low cost, low energy intensity and serviceability of the required equipment. It is also recommended to include the proposed formula for calculating the dose of hydrogen peroxide in the recommendations of CP 31.13330.2021 on groundwater de-ironing.

Key words

deferrization , ground water , water treatment , hydrogen sulfide removal , hydrogen peroxide , regulatory guidelines

Reconstruction of the ground water treatment plant
in Noyabrsk (Yamal-Nenets Autonomous Okrug)

Summary

The main results of technological surveys that form the basis for the project of reconstruction of the ground water treatment plant in Noyabrsk (Yamalo-Nenets Autonomous Okrug) are presented. The plant was built according to the project of DAR/VODGEO CJSC (Moscow) and commissioned in September 2006. The plant uses a new technology that provides for the sequential treatment of water with two oxidizing agents – hydrogen peroxide and potassium permanganate to remove iron and manganese compounds. The project shortcomings and incomplete implementation of design solutions complicate the regular operation of the plant and make it difficult to ensure the standard quality of drinking water. It was stated that ground water contained hydrogen sulfide in concentrations up to 0.1 mg/dm³, which required extra consumption of chemicals. Manual dosing of chemicals causes significant deviations from the required doses: from –14.5 to +19.1% for hydrogen peroxide and from –8.5 to +9.1% for potassium permanganate. It is pointed out that crude products of potassium permanganate produced by the P. R. China used as a chemical agent in drinking water supply, pose a threat of increased toxicity of drinking water. The determined value of the Langelier index (index of saturation with calcium carbonate) of ground water (–2.35 units) allowed to conclude that stabilization treatment by alkalization is required. The performed test water treatment with hydrogen peroxide and potassium permanganate in combination with alkalization showed that this process provided for achieving the residual concentrations of manganese < 0.1 mg/dm³ and total iron 0.1–0.15 mg/dm³ in the absence of residual hydrogen sulfide. However, to produce water of constant standard quality, high accuracy of chemical dosing is required that can only be provided by completely automated dosing. The project of upgrading the ground water treatment plant in Noyabrsk designed on the basis of technological research, allows to resolve the existing problems and ensure the standard quality of drinking water.

Ключевые слова

deferrization , ground water , hydrogen peroxide , potassium permanganate , demanganization , stabilization treatment , caustic soda , hydrogen sulfide removal