DOI 10.35776/MNP.2020.02.02
UDC 628.16.065.2-926
Oskolkov N. V., Bogdanov B. A., Mamaev V. V., Borovkov M. L., Nazarenko N. P., Golovin V. M., Pan’kov A. S.
Selection of optimal coagulation technologies and chemicals
for the purification of specific natural waters
(for discussion)
Summary
Over the past 25 years the leading Russian manufacturers of coagulants have been continuously busy with the optimization of processes, technologies, chemicals, facilities and equipment associated with coagulation of water primarily from water sources of specific composition – rivers of the North-West and South of Russia, Western Siberia and the Far East, Kazakhstan, etc. Mixed coagulants based on the synergistic effect of the interaction of components provide for an effective solution for purifying water of complex composition. In May 2020, the new GOST R 58580-2019 «Polyaluminum chloride. Technical Specifications» will come into effect that recommends the use of the chemical to the Russian water utilities regardless of the specific characteristics of the water sources used for water supply. This standard unreasonably regulates a number of indicators, iron concentration, in particular. This devaluates the efforts of researchers and practitioners aimed at improving the processes of purifying water of complex composition using iron-containing mixed chemicals.
Key words
aluminium polyoxychloride , mixed iron-containing coagulants , specific natural water , optimal coagulation technologies and chemicals
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UDC 628.16.081:661(24+48+63)
Gandurina L. V., Potapova L. V.
Precipitating capacity of AQUA-AURAT™30 coagulant in water treatment in the presence of calcium hydroxide
Summary
The results of experimental studies of simultaneous elimination of sulphates, phosphates and fluorides from water with AQUA-AURAT™30 aluminium polyoxychloride in the presence of calcium hydroxide are presented. It was shown that the standard concentration of sulphates and phosphates is ensured with the chemical dosage ratio 4.5 (as active СаО/Аl2О3) and рН 11. Fluoride concentration under the circumstances is decreasing from 11 to 2 mg/l. The standard fluoride concentration in treated water is ensured at рН 7.
Key words
coagulant , water treatment , phosphates , aluminium polyoxychloride , calcium hydroxide , sulphates , fluorides
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DOI 10.35776/MNP.2020.01.02
UDC 628.1:006.3:66-926
Samburski Georgi, Ustinova O. V., Leont’eva S. V.
Specific features of standardization of chemicals
for the preparation of drinking water (through the example of polyaluminium chloride coagulant)
Summary
Coagulation process has been a widespread process technology for removing coarse suspended impurities from water, as well as colloidal organic contaminants present in dissolved form. Polyvalent metal salts are effective coagulants for the systems with aqueous disperse medium. The purpose of the work was developing a new state standard to provide for a uniform assessment of the quality of coagulants. The scope of coagulants in the process of water treatment is considered and their comparative analysis is carried out. The general requirements to the control of polyaluminium chloride quality are formulated. The developed and approved new national standard GOST R 58580-2019 «Polyaluminium chloride. Technical conditions» is presented that takes into account the requirements of sanitary legislation, technical regulation, safety of the processes of production and transportation of polyaluminium chloride.
Key words
water treatment , water treatment , aluminium polyoxychloride , coagulants , standardization of chemicals
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UDC 628.161.3
Getmantsev S. V., Sychev A. V., Getmantsev V. S.
Prospects of coagulation water treatment
Summary
Despite the significant progress and increasing popularity of membrane water treatment methods chemical treatment keeps holding tightly its position. One of the most important characteristics of coagulants based on polyaluminium chloride is the basicity. The basicity, all other conditions being equal, determines the dealkylation rate and pH of water subject to coagulation. The value of pH obtained after coagulant hydrolysis, in its turn, determines the zeta potential of colloids present in water and kinetic persistence of the colloid system. During coagulation each type of colloid water pollutants has corresponding optimal pH value. The development of the technology of polyaluminium chloride production from high-purity metallic aluminium by «Aurat» JSC resulted in market launch of EPOKHA™ coagulant trademark with 40–83% basicity. The use of EPOKHA™ provides for choosing an optimal modification of polyaluminium chloride for every customer and every climatic season. Another new product manufactured by «Aurat» OJSC under GranEKO™ trademark is crystalline aluminium chlorhydrate with 65–83% basicity. The concentration of active matter in such product is up to 50% as Al2O3. High basicity provides for using GranEKO™ for the clarification of water with low alkaline reserve eliminating the use of alkalizing agents. An important trend in developing chemical water treatment means is the development of composite chemicals combining inorganic coagulant and organic polyelectrolyte. New composite chemicals of ERCHV™ series present a combination of coagulant based on aluminium salt, polydiallyldimethylammonium chloride and modifying additives that provide for the synergetic effect and storage stability. The variety of characteristics of water subject to treatment and applied process flow schemes require an integrated approach to the problem of pH correction during coagulation by using coagulant with higher or lower basicity and changing the injection point.
Key words
coagulation , residual aluminium , aluminium sulphate , aluminium polyoxychloride , chemical water treatment methods , basicity
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UDC 628.162
Gandurina L. V., Gavrilova N. N., Kuzin E. N., Raff P. A.
The use of the dynamic light scattering method for characterizing humic acids in natural water
Summary
The results of studying the impact of sodium, calcium and aluminium salts on the dispersive characteristics of humic acids in natural water with the use of Photocor Compact-Z analyzer are presented. The dispersiveness of humic acids by molecular mass determines to wide extent the efficiency of natural water decoloration with aluminium salts. It is shown that the method of dynamic light scattering can be an efficient and rapid method of studying the conformational changes of macromolecules in alkaline and acid solutions, and chemical interactions between humic acids and metal ions. The studies were carried out with natural and simulated water prepared by extracting humic acids from peat with distilled water and blending the obtained solutions to the required color. The ion composition of simulated water was changed by adding calcium chloride, aluminium sulfate, «Aqua-Aurat™30» polyaluminum oxychloride, sodium hydrogen carbonate and hydrochloric acid.
Key words
chromaticity , natural water , aluminium sulphate , aluminium polyoxychloride , humus acids , alkalinity , light scattering
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DOI 10.35776/VST.2022.05.04
UDC 628.345
Stepanov S. V., Avdeenkov Pavel, Ponomarenko Ol’ga, MOROZOVA K. M.
The results of studies of physical and chemical wastewater treatment of an egg processing enterprise
Summary
The composition of wastewater of an enterprise for advanced processing of chicken eggs characterized by the following parameters: COD 3,600–12,200mg/l, concentration of suspended solids 1,206–3,031 mg/l, BODtotal 2,534–8,540 mg/l, no phosphates, pH 5.4– 13.2 was studied. The concentration of nitrogen compounds, mg/l, varied within the following ranges: ammonium – 0.4–11.4; nitrates – 0–15.3; nitrites – 0–7.3; organic nitrogen – 26.6–89.7. Based on the results of test coagulation, the optimal coagulant chosen was low-basic polyaluminum chloride brand «Aqua-AuratTM-14» with a dose of 125 mg/l as Al2O3. The average treatment efficiency while using this coagulant was, %: for COD – 77.3; for BODtotal – 76.3; for suspended solids – 80.1; for organic nitrogen – 58.7. The lowest concentration of residual aluminum 0.31 mg/l at the initial concentration of 0.29 mg/l corresponded to pH 6.7–7. Unit costs for the coagulant amounted to 9.37 rubles/m3.
Key words
wastewater , coagulation , aluminium polyoxychloride , food industry , physical and chemical treatment , egg processing enterprise
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UDC 628.168.4
Gandurina L. V., Getmantsev S. V., Raff P. A., Nikiforova A. Ju.
Chemical aspects of decoloration of low turbidity natural water with aluminium salts
Summary
The mechanism of decoloration of natural water with aluminium sulfate aluminium polyoxychloride is considered. The complexing reactions of humus acids with aluminium salts mainly contribute to the decoloration of natural water. The parallel proceeding reaction of aluminium sulfate and polyoxychloride hydrolysis facilitates the reduction of aluminium ion concentration in treated water but does not reduce color. Empirical dependences of coagulant dosages on color and alkalinity of raw water have been determined. Higher efficiency and lower dosages of aluminium polyoxychloride compared to aluminium sulfate used for decoloration are stipulated by the polymer origin of aluminium polyoxychloride. The use of coagulants in combination with cationic Praestol 650 flocculant provides for improving the efficiency of decoloration by 10–20% at the optimal coagulant: flocculant ratio of 50:1 for aluminium polyoxychloride and 20:1 for aluminium sulfate.
Key words
chromaticity , natural water , aluminium sulphate , cationic flocculant , aluminium polyoxychloride , humus acids , alkalinity , hydrolysis , complexing
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