Pilot testing the technology of low-turbid colored water conditioning in the process of two-stage filtration

Summary

The results of the pilot tests of the technology of low-turbid colored water conditioning by two-stage filtration are presented. The tests were carried out to specify the parameters of the technology being developed and to determine the effectiveness of water purification of the Zeya River (Amur Region) with a view to its use in domestic and industrial water supply of the designed industrial facility. During the test period the river water was characterized by low temperature (3.5–7.5 °С), low pH values (6.5–6.7) and alkalinity (0.4–0.5 mg-eq/dm³) with color up to 80 degrees. To specify the chemical dosages preliminary (laboratory) tests were carried out. It was established that the treatment of river water with sodium hypochlorite provided for a noticeable bleaching effect – up to 40%. However, increasing the oxidizer dosage to more than 10 g/m³ is ineffective. At the specified river water color the dosage of chemical can be set within 5–7 g/m³. Owing to low alkalinity values it is recommended to alkalize water with soda ash at an optimal dose of 6 g/m³. According to the results of the test chemical treatment of water the preference was given to Aqua-Aurat™30 coagulant at doses of 35–40 g/m³. By comparison of the flocculants of Praestol group, Praestol 650TR showed the best results at doses of 0.1–0.15 g/m³. Pilot tests of purifying Zeya river water proved the high efficiency of the two-stage filtration technology (contact prefilter + rapid filter). The use of Aqua-Aurat™30 coagulant in combination with Praestol 650TR flocculant ensured the standard quality of drinking water, as well as the quality required for industrial water supply of the designed industrial facility.

Key words

sodium hypochlorite , water treatment , coagulant , flocculant , low-turbid colored river water , two-stage clarification , soda ash

Pre-project in-process testing river water purification in the Arctic Circle

Summary

The results of pre-project in-process testing purification of water of the Vary-Khadyta River, the source of drinking and domestic water supply for the village of Yar-Sale (Yamal-Nenets Autonomous Okrug), are presented. Throughout the year the permissible concentration of iron, manganese, suspended solids and compounds in the river water that cause the water color is exceeded. Low temperatures, alkalinity and salinity result in the low level of water stability (Langelier index from –3.8 to –1.1 points). Water treatment facilities in Yar-Sale village (WTF-50) do not provide for the standard quality of purified water. This due to both incorrect water treatment technology that involves only filtration for clarification, and an incomplete set of chemicals required to produce drinking water. During the upgrade of the treatment facilities replacing the technology with the traditional clarification flow scheme (sedimentation – filtration) because of the periodic use of high doses of coagulant, as well as supplementing the chemical treatment with processes of alkalization and oxidation of the river water manganese with potassium permanganate was proposed. To assign the design modes of chemical water treatment, in-process tests were carried out under the conditions of the WTF of Yar-Sale village. For clarification and color removal, the chemicals used at the WTF of Yar-Sale village were applied (POHA «Aqua-Aurat-30^TM» coagulant, flocculant Praestol 2530). It is shown that using only these chemicals did not provide for the standard quality of drinking water. To enhance the efficiency of purification, it is proposed to carry out chemical treatment in two stages: upstream the sedimentation tanks – alkalization, coagulation and flocculation, then upstream the filters – additional alkalization, oxidation of manganese with potassium permanganate and additional flocculation. The operational doses of chemicals were determined, that ensure the production of stable drinking water meeting the requirements of the current regulatory documents. Based on the test results obtained, a standard operating procedure for designing the upgrade of the WTF-50 of Yar-Sale village was developed.

Key words

deferrization , potassium permanganate , demanganization , river water , stabilization treatment , soda ash , color removal , «Aqua-Aurat-30тм» , Praestol 2530