Most often, reagent methods are used to treat wastewater from Cr (VI) compounds. This treatment technology allows reducing the concentration of Cr (VI) in wastewater only. Comparing the composition of wastewater after reagent treatment of chromium compounds using Ca(OH)2 with established standards, it can be concluded that it is necessary to purify a number of pollutants. In this study, wastewater afterpurification of chromium compounds production by the ultrafiltration and reverse osmosis was considered. Modelling processes using WAVE 1.72 software confirmed that the proposed post-treatment scheme was highly efficient and that wastewater could be discharged into a water body without harming it. © Published under licence by IOP Publishing Ltd

Potapova, E. A.

Pugachev, D. D.

Tretyakova, N. A.

IOP Conference Series Earth and Environmental Science

Institutional repository of Ural Federal University named after the first President of Russia B.N.Yeltsin

IOP Conference Series: Earth and Environmental SciencePAPER • OPEN ACCESSWastewater afterpurification of chromiumcompounds production by the ultrafiltration andreverse osmosisTo cite this article: E A Potapova et al 2021 IOP Conf. Ser.: Earth Environ. Sci. 864 012048 View the article online for updates and enhancements.You may also likePilot Study on Catalyzed Oxidation-Ceramic Membrane-High PressureReverse Osmosis for DesulfurizationWastewater RecoveryZhongjie Wu, Yaqin Hou, Xinmei Li et al.-New Trends in the Development ofPolymeric Materials for Reverse OsmosisMembranesYu E Kirsh and Yu M Popkov-Design and performance of small-scalereverse osmosis desalination for brackishwater powered by photovoltaic units: areviewVo Nguyen Xuan Que, Doan Van Tuan,Nguyen Nhat Huy et al.-This content was downloaded from IP address 212.193.94.28 on 12/04/2022 at 14:36Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdSino-Russian ASRTU Forum “Ecology and Environmental Sciences”IOP Conf. Series: Earth and Environmental Science 864 (2021) 012048IOP Publishingdoi:10.1088/1755-1315/864/1/0120481      Wastewater afterpurification of chromium compounds production by the ultrafiltration and reverse osmosis E A Potapova, D D Pugachev and N A Tretyakova Institute of Chemical Engineering, Ural Federal University, 620002 Ekaterinburg, Russia n-tretyakova@mail.ru Abstract. Most often, reagent methods are used to treat wastewater from Cr (VI) compounds. This treatment technology allows reducing the concentration of Cr (VI) in wastewater only. Comparing the composition of wastewater after reagent treatment of chromium compounds using Ca(OH)2 with established standards, it can be concluded that it is necessary to purify a number of pollutants. In this study, wastewater afterpurification of chromium compounds production by the ultrafiltration and reverse osmosis was considered. Modelling processes using WAVE 1.72 software confirmed that the proposed post-treatment scheme was highly efficient and that wastewater could be discharged into a water body without harming it. 1.  Introduction Enterprises specializing in the production of chromium compounds are a dangerous source of pollutants in wastewater that can have a negative impact on the environment. The wastewater of these enterprises contains extremely toxic substance – chromium (VI). To prevent pollution of water reservoirs, wastewater is required to be treated. Various methods are used to remove chromium (VI) from wastewater [1-5]. A comparative analysis of various methods of wastewater treatment from chromium compounds is carried out in [6]. Most often, reagent methods are used to treat wastewater from Cr (VI) compounds. Figure 1 shows a reagent wastewater treatment scheme [7].  Figure 1. Structural diagram of reagent wastewater treatment and disposal. Wastewater Ca(OH)2 FeSO4 Cr (VI) reduction Wastewater clarification in a slurry tank Water discharge Sino-Russian ASRTU Forum “Ecology and Environmental Sciences”IOP Conf. Series: Earth and Environmental Science 864 (2021) 012048IOP Publishingdoi:10.1088/1755-1315/864/1/0120482      The reagent methods are based on the reduction of dissolved Cr (VI) with FeSO4 to less toxic Cr (III), which in base conditions precipitates as sparingly insoluble hydroxides and is removed from water. After purification, the mass concentration of Cr (VI) is not more than 0.06 mg/dm3, and the pH is 6.5-8.3 [6]. These values satisfy regulatory requirements. This treatment technology allows reducing the concentration of Cr (VI) in wastewater only. The contents of other pollutants during the cleaning process do not change remaining their initial values. In addition, using reagents in purified water increases the content of sulphates and iron [7]. Table 1 shows the average seasonal composition of contaminants in the wastewater of AO “Russian Chrome 1915” after their purification by the reagent method [2]. When wastewater is discharged into water bodies, their quality should satisfy the requirements. The most stringent requirements are the standards for fishery water reservoirs – MPCrh. Comparing the composition of wastewater after reagent treatment of chromium compounds using Ca(OH)2 with established standards, it can be concluded that it is necessary to purify a number of pollutants. Table 1. The composition of wastewater after reagent treatment of chromium compounds and standard for effluents composition. Wastewater composition indicators The wastewater composition of AO “Russian Chromium 1915”, mg/l Standard for effluents composition of fishery water body (MPC), mg/l Iron (general) 0.7-1.0 0.10 Chloride ion 150.0-200.0 300.00 Sulphate ion 2000.0-4000.0 100.00 Suspended solids 5.0-30.0 14.95 Nitrate ion 20.0-40.0 40.00 Ammonium ion 20.0-40.0 0.50 One of the most effective methods for removing various ions from water is membrane technology. Membrane systems are used to remove bacteria, protozoa, and viruses, prepare high-quality drinking water, and partially or deeply desalinate the water [8]. Ultrafiltration and reverse osmosis allow concentrating and separating the pollutants dissolved in wastewater. Thus, the aim of this work is to develop wastewater afterpurification of chromium compounds production by the ultrafiltration and reverse osmosis. 2.  Methods In the work, a calculation of a wastewater treatment plant including the stage of ultrafiltration and reverse osmosis was made. Ultrafiltration and reverse osmosis processes were simulated using the WAVE 1.72 software [9]. 3.  Results The proposed flow chart of wastewater afterpurification of chromium compounds production wastewater treatment is presented in Figure 2. After the reagent removal of Cr (VI), the wastewater containing pollutants is pumped (item 1) to the ultrafiltration unit (item 3), where it is purified from iron and suspended substances. The obtained filtrate is sent to an intermediate collector (item 10), and the concentrate enters the sewage regulator (item 4), from where it is pumped to mix with the initial wastewater. Most of the filtrate is then sent for purification to the reverse osmosis unit (item 11), and the rest is periodically used for backwashing the membranes of the ultrafiltration unit. Wash water containing impurities of iron and suspensions trapped on the membranes is received in the averaging tank (item 6). Sino-Russian ASRTU Forum “Ecology and Environmental Sciences”IOP Conf. Series: Earth and Environmental Science 864 (2021) 012048IOP Publishingdoi:10.1088/1755-1315/864/1/0120483       Figure 2. Flow chart of wastewater treatment. I – wastewater for treatment, II – purified water, III – for evaporation plant. 1 – pump; 2 – valve; 3 – ultrafiltration unit; 4 – tank with concentrate; 5 – neutralizing tank; 6 – sewage regulator 7 – dosage block of NaOH; 8 – dosage block of HCl; 9 – dosage block of NaOCl; 10 – an intermediate tank; 11 – reverse osmosis plant; 12 – capacity with purified wastewater; 13 – tank with a concentrate for reverse osmosis; 14 – tank-neutralizer for reverse osmosis; 15 – sewage regulator of reverse osmosis plant. The ultrafiltration filtrate from the intermediate collector (item 10) is pumped to the reverse osmosis membrane system (item 11) for wastewater treatment from residual iron, suspended solids, sulphate, nitrate, ammonium, and chloride ions. The obtained permeate is taken to the collection of purified water (item 12), from where it is sent to the consumer (to circulating water supply systems or to the technological process). The concentrate enters the tank (item 13) for co-recycling with ultrafiltration wastewater. Part of the permeate from the collection (item 12) is used for periodic washing of reverse osmosis membranes, which is carried out by the pump. The wash water is sent to the averaging tank of the ultrafiltration unit (item 6). Once a day, chemical washing of the reverse osmosis membranes with solutions of NaOH, HCl and NaOCl (for disinfection) is carried out by feeding them from dosing units (items 7-9). Water from chemical washing is supplied to the neutralization tank (item 5), where it is treated together with similar waters of the ultrafiltration unit and then transferred to the evaporation unit to reduce the volume of wastewater. Based on the wastewater flow rate equal to 160 m3/h, it is proposed to use two PVO-UF-80 ultrafiltration units (capacity 80 m3/h), including 16 ultrafiltration modules each. For selected ultrafiltration units, it is proposed to use IntegraPac IP-51XP modules equipped with PVDF (polyvinyl difluoride) membranes. The specifications of the membrane elements are presented in Table 2 [10]. As a result of ultrafiltration purification, part of the water is spent on the plant’s own needs, while other part is left with concentrate, so the permeate volume was 135.8 m3/h. The calculation of the reverse osmosis was carried out by this value. To conduct reverse osmosis, it is proposed to use three reverse osmosis plants MA-50 (the productivity of each installation is 50 m3/h). As membranes, high-performance low-pressure roll membrane elements FORTILIFE XC80 are used, the specifications of which are given in Table 3 [11]. The permeate output from the reverse osmosis unit will be 94.54 m3/h. Sino-Russian ASRTU Forum “Ecology and Environmental Sciences”IOP Conf. Series: Earth and Environmental Science 864 (2021) 012048IOP Publishingdoi:10.1088/1755-1315/864/1/0120484      Table 2. Main specifications of the module type IntegraPac IP-51XP. Specifications Unit Value Membrane surface area m2 51 Module outer diameter mm 225 Case material – PVC-U Maximum pressure bar 6.25 Temperature range °С 1-40 Capillaries in fibre pс. 7 Inner diameter of the capillaries mm 1.5 Outer diameter of the capillaries mm 6.0 Pore size mkm 0.02 Material – PVDF Table 3. Main specifications of the membrane type FORTILIFE XC80. Specifications Unit Value Membrane surface area membrane m2 41 Module outer diameter m 201 Configuration – roll Maximum pressure MPa 8.3 Temperature range °С 1–45 Pore size mkm 0.001 Material – Polyamide Selectivity % 99.5 Table 4 presents the calculation results of the proposed wastewater treatment plant obtained using the WAVE 1.72 software. Comparison of the obtained results of the quality of treated wastewater with standards (MPCrh) shows that the proposed post-treatment scheme is highly efficient, and wastewater can be discharged into a water reservoir without harming it. Table 4. Efficiency of wastewater treatment by ultrafiltration and reverse osmosis obtained using WAVE 1.72 software. Wastewater composition indicators Concentration of pollutants, mg/l Standard for effluents composition of fishery water body (MPC), mg/l Wastewater Permeate After ultrafiltration After reverse osmosis Suspended solids 30.00 0 0 14.95 Sulphate ion 2000.00 2000.00 0.58 100.00 Nitrate ion 40.00 40.00 1.13 40.00 Ammonium ion 20.00 20.00 0.39 0.50 Chloride ion 200.00 200.00 0.77 300.00 Sino-Russian ASRTU Forum “Ecology and Environmental Sciences”IOP Conf. Series: Earth and Environmental Science 864 (2021) 012048IOP Publishingdoi:10.1088/1755-1315/864/1/0120485      4.  Conclusion Wastewater treatment is an important stage in the work of the enterprise, since the state of the environment, in particular water bodies, depends on the quality of the wastewater discharged. The work has developed a flow chart for the wastewater treatment of enterprises producing chrome compounds. Wastewater after the reagent method is sent to the proposed scheme including ultrafiltration and reverse osmosis treatment unit. Based on the wastewater flow rate equal to 160 m3/h, it is proposed to use two PVO-UF-80 ultrafiltration units (capacity 80 m3/h), including 16 ultrafiltration modules each. For selected ultrafiltration units, it is proposed to use IntegraPacIP-51XP modules equipped with PVDF (polyvinyl difluoride) membranes. As a result of ultrafiltration purification, part of the water is spent on the plant’s own needs, while other part is left with concentrate, so the permeate volume was 135.8 m3/h. To conduct reverse osmosis, it is proposed to use three reverse osmosis plants MA-50 (the productivity of each installation is 50 m3/h). As membranes, high-performance low-pressure roll membrane elements FORTILIFE XC80 are used. The permeate output from the reverse osmosis unit is 94.54 m3/h. Modelling processes using WAVE 1.72 software has confirmed that the proposed post-treatment scheme is highly efficient, and wastewater can be discharged into a water body without harming it. References [1] Loskutov V I and Zalevsky D V 2012 Bull. Lobachevsky Univ. Nizhny Novgorod 5-2 148 [2] Mullakaev M S, Wexsler G B, Khramtsov A P and Vachitov A R 2016 Int. Sci. Tech. Conf. “Improving the Efficiency of Processes and Devices in Chemical and Related Industries” (Moscow) 163 [3] Khabibrakhmanova A I, Ugina N A, Khabibrakhmanov V Z, Mikhailova E O and Shulaev M V 2014 Bull. Kazan Tech. Univ. 17 223 [4] Nistratov A V, Klushin V N and Erofeeva V B 2012 Adv. Chem. Chem. Technol. 26 94 [5] Zoubareva G I, Filipyeva M N and Degtev M I 2005 Ecol. Ind. Rus. 2 30 [6] Krivoshein D A, Ostaev D G and Zvolinski V P 2003 RUDN J. Ecol. Life Safety 9 48 [7] Perelygin U P, Zorkina O V, Rashevskaya I V and Nikolaeva S N 2013 Reagent Treatment of Wastewater and Disposal of Waste Solutions and Precipitation of Electroplating Plants (Penza: Penza State University Press) [8] Vetoshkin A G and Tarantseva K R 2004 Technology of Environmental Protection (Theoretical Foundations) (Penza: Publishing House of the Penza Technological Institute) [9] Wave Software for Water Treatment Plant Design 2020 (DUPONT. Water Solutions) https://www.dupont.com/water/resources/design-software.html [10] IntegraPac™ IPD-51XP Module 2020 (DUPONT. Water Solutions) https://www.dupont.com/products/integrapacipd51xpmodule.html [11] FilmTec™ Fortilife™ XC80 Element 2020 (DUPONT. Water Solutions) https://www.dupont.com/products/filmtecfortilifexc80element.html 

Wastewater Afterpurification of Chromium Compounds Production by the Ultrafiltration and Reverse Osmosis

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Wastewater Afterpurification of Chromium Compounds Production by the Ultrafiltration and Reverse Osmosis

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