The experience of using «dry» filtration technology in underground water conditioning

Summary

Iron, being one of the most abundant elements of the Earth crust, is present almost everywhere in the water of shallow aquifers in the form of soluble compounds, or sometimes in the form of compound organic matter. High concentrations of iron in water cause corrosion and blockages in pipes either directly by forming deposits or indirectly providing the conditions for specific bacterial growth. For this and some other reasons iron is removed from the water from the sources with elevated iron concentrations before supply to the consumers. The examples of the «dry» filtration technology used by the engineering and construction companies of Tver in the process of underground water conditioning are presented. The theoretical basis of the technology was formulated by G. Iu. Asse, expert of NII VODGEO. As a result of the longstanding cooperation with the designers from Tver the process flow scheme of underground water de-ironing was developed together with the process equipment – a set of aero-filters of various capacities. This provided for designing a number of de-ironing installations which surpass by a number of parameters the well-known de-ironing technical solutions implemented in typical and individual projects. Technical solutions developed and implemented in practice provide for placing aero-filters in one building with a booster pumping station, filter media regeneration pumps, a compressor station, UV-disinfection system, and auxiliary rooms.

Key words

deferrization , ground water , aquifer , «dry» filtration , aero-filter , gravel media , dirt holding capacity of the media

Removing hydrogen sulfide from water with air oxygen
by the method of «dry» filtration in anthracite media

Summary

One of the causes that limit the widespread use of artesian waters is the presence of hydrogen sulfide. The method of removing hydrogen sulfide from water by converting the ionic forms HS^- and S^2- into molecular H₂S (acidification of water to pH ≤ 5) with subsequent degassing is not environmentally friendly due to air pollution with hydrogen sulfide blown away in the degasser. Oxidation of hydrogen sulfide to elemental sulfur or its oxides is carried out with the use of expensive oxidants that while being applied require special safety measures. An effective chemical free method of removing hydrogen sulfide from water can be the use of an oxidizing filter consisting of a sealed housing partially filled with non-submerged catalytic electrically conductive anthracite media with a grain size of 0.8–2 mm. Air is injected into the distribution perforated water feeding system located above the media. Herewith, the tightness of the filter eliminates the emission of hydrogen sulfide into the atmosphere and pollution of the room, whereas the entire volume of the catalytic media is residing in an oxygen-containing environment in the most active mode of catalytic oxidation of hydrogen sulfide. Purified water is collected at the bottom of the filter in a collector with an air outlet connected to it. After 2–4 days of operation, the filter is removed from the filtration mode to regenerate the catalytic media by back air washing with the removal of elemental sulfur S⁰ formed during the oxidation of hydrogen sulfide.

Key words

liquid-phase oxidation , «dry» filtration , hydrogen sulfide-containing underground water , anthracite filtering media , air oxygen