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1

Reducing Tannery Wastewater Pollutants through a Magnetic-Field and Ozone-Treatment Electrocoagulation System using Response Surface Methodology

Aguilar Ascon Edwar, Marrufo Saldaña Liliana, Neyra Ascón Walter

Journal of Ecological Engineering

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2024

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Vol. 25, nr 1

74--83

EN

This study assessed the effectiveness of integrating electrocoagulation, magnetic fields, and ozonation technologies to remove chemical oxygen demand (COD) and total suspended solids (TSS) from tannery wastewater. Furthermore, the effects of their key operating factors were determined. To achieve this goal, an electrocoagulation reactor coupled with a magnetic-field generator was used and the response surface methodology was applied through a Box-Behnken experimental design. Here, current intensity (I), treatment time (T), and ozone concentration (O3) are considered the influencing factors. Likewise, the removal percentages of COD and TSS serve as response indicators. The results indicate that T, I, and O3 are significant for the removal of COD and TSS at a confidence level of p-value < 0.05. For COD, the optimal operating conditions are I = 6.8 A, T = 30 min, and O3 = 10 mg/l; and for TSS, the optimal conditions are I = 5.72 A, T = 28 min, and O3 = 7.8 mg/l. These conditions yield removal efficiencies of 41.8% for COD and 97.9% for TSS. The findings suggest that integrating these technologies is a viable alternative for mitigating the pollution issues caused by the tannery industry.

2

Optimization of Chromium Removal from Tannery Effluents with the Neonite Natural Zeolite

Barra-Hinojosa Julio, Marrufo-Saldaña Liliana, Salazar-Leiva Victor, Gómez-León Mónica, Solis-Veliz Jose

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 2

41--53

EN

Chromium is the main constituent of the tanning salts used by tanneries for processing skins into leather, and considered as a pollutant in the effluents that this industry discharge. The present study aimed to evaluate the removal of chromium and other pollutants in effluents from the tanning industry applying the natural zeolite Neonite. Neonite is a commercially available zeolite, which was acquired from NEONITE S.A. Neonite was characterized through FTIR and XRD, identifying clinoptilolite as its main component. Treatment was applied to the samples of real effluents from the tanning stage or chromium bath (CB) and a composite effluent (CE), an experimental design was carried out for each effluent. The designs correspond to 32 factorial designs, the variables tested were the Neonite dosage (NE) measured in g/L, stirring time (StT) expressed in minutes and the pH of the sample, and the response variable was the residual chromium content (RCC). Statistical analysis was performed through R-software version 4.2.3 and included Box-Cox transformation and ANOVA to determine the main effects and the behavior of the response variable in relation to the applied model and its optimization by response surface. In CB, a removal above 95% was obtained for RCC, with optimization values at 32 g/L of NE and pH 7. In the CE, a removal of more than 98% was obtained for RCC and values higher than 60% for BOD, COD, TSS and Fats, being the optimal conditions 4.73 g/L of NE and 12.17 minutes of StT. These results demonstrate that the application of Neonite for the removal of chromium and other pollutants from tanning industry effluents has a great potential.

3

Potential of electrocoagulation technology for the treatment of tannery industrial effluents: A brief review

Kumar Verma Rishi, Gautam Kajal, Agrahari Sakshi, Kumar Sushil

Chemical and Process Engineering

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2022

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Vol. 43, nr 2

217–-222

EN

In this new era, we are facing a major problem regarding wastewater in the environment, which has an adverse effect on human life. Wastewater from tanning industries is one of the major contributors to the pollution in aquatic systems. Tannery industries have always contributed to the world’s economy and trade despite facing criticism due to environmental pollution. Tanning effluent consists of organic, inorganic (chromium, nitrogenous compounds), and a large amount of solid content like TDS, TSS, TVS. To overcome these significant challenges, there have been few advancements related to tannery wastewater treatment. This article aims to provide a brief review on electrocaogulation based treatment technologies for eliminating the impurities from tannery wastewater. This review consists of the background with characteristics of tannery wastewater, the alternatives for treating the tannery effluent over the years along. A detailed description of the advanced technologies based on electrocoagulations is implemented to overcome the drawbacks of the existing methods.

4

Reduction of Total Chromium Levels from Raw Tannery Wastewater via Electrocoagulation using Response Surface Methodology

Aguilar-Ascón Edwar, Marrufo-Saldaña Liliana, Neyra-Ascón Walter

Journal of Ecological Engineering

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2019

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Vol. 20, nr 11

217--224

EN

This study focused on reducing total chromium levels in raw wastewater from the leather tanning industry via electrocoagulation to comply with maximum permissible limits (MPL) and to determine the effects of main process parameters. An electrocoagulation reactor was built using aluminum electrodes as an anode and cathode. Then, the response surface methodology was applied using a 3k factorial design considering three factors, namely current intensity, treatment time, and pH. The total chromium removal percentage was considered as a response variable. 99% of the total chromium found in wastewater could be removed after 14-min treatment at 2-A current intensity and pH 5.5. Similar amount of chromium was removed at pH of 8.5 and 7. Statistical analysis performed at a confidence level of p < 0.05 revealed that all three factors influenced electrocoagulation. Total chromium could be efficiently removed from raw wastewater at a current intensity of 2.9 A, a pH of 8.4, and a treatment time of 21 min, suggesting that electrocoagulation using aluminum electrodes is an efficient method for total chromium removal. Thus, this process must be considered as a solution to the problems caused by the leather tanning industry and for better compliance with the MPL established in the Peruvian environmental standards.

5

Alternative Treatment Strategy for Different Streams of Tannery Wastewater

Przywara L.

Journal of Ecological Engineering

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2017

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Vol. 18, nr 4

160--168

EN

This article discusses the results of laboratory tests aimed to determine the effectiveness of tannery wastewater treatment in the process of enhanced oxidation using Fenton reagent. The general sewage from the tannery located in Mazowieckie Province was used for the research. The process was carried out using two doses of iron of 0.45 g Fe2+/dm3. and 0.56 g Fe2+/dm3, and H2O2 from 2.21 g/dm3 to 4.08 g/dm3. All the tests were performed for a constant optimum pH of 3.0. Wastewater was characterized by basic physico-chemical indicators (pH, conductivity, COD, chromium, ammonium nitrogen). The efficiency of the process was determined mainly on the basis of changes in the organic pollutants identified as COD. The efficacy of the Fenton process for different doses of Fe2+ and Fe2+ / H2O2 ratio of 1: 5, 1: 6 and 1: 7 was from 69 to 80% COD reduction in relation to raw sewage. Another aspect of the study was determining the possibility of removing sulphides from the wastewater by catalytic oxygenation with oxygen from air in the presence of manganese. In this case, the wastewater produced during leather manufacture in tanneries located in the southern part of Poland was examined. The subject of the study described in the paper was to determine the optimum manganese dose and oxidation time to simultaneously remove the sulphides and organic pollutants expressed as COD. The change in pollutant content in the wastewater over time indicates that the reduction of parameters takes place within one hour after the addition of manganese. Using the process of catalytic oxidation with 0.1 g/dm3 to 0.6 g/dm3 manganese and a reaction time of 1, 3, 24 h, the sulphides were removed in the range of 50 to 99% and organic compounds in 12 to 65%.

6

Zastosowanie procesu Fentona do oczyszczania ścieków garbarskich

Przywara L.

Inżynieria Ekologiczna

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2017

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Vol. 18, nr 2

117--122

PL

W artykule omówiono badania, których celem było określenie efektywności oczyszczania ścieków garbarskich w procesie pogłębionego utleniania z zastosowaniem odczynnika Fentona. Proces przeprowadzono stosując różne dawki żelaza zmieniane w zakresie od 0,056 g Fe2+/dm3 do 0,56 g Fe2+/dm3, H2O2od 0,34 g/dm3 do 5,44 g/dm3 i w zakresie pH od 2,5 do 3,5. Ścieki scharakteryzowano wykonując oznaczenia podstawowych wskaźników fizyko-chemicznych (pH, przewodność, ChZT, chrom, azot amonowy). Badano także możliwość zastosowania procesu koagulacji przy użyciu koagulantu SAX 18. Efektywność procesu określono w oparciu o zmiany głównie wartości zanieczyszczeń organicznych określonych jako ChZT. Skuteczność procesu Fentona prowadzonego dla dawki Fe2+ na poziomie 0,56 g Fe2+/dm3i H2O2 4,08 g/ dm3 wynosiła 80% zmniejszania ChZT w stosunku do ścieków surowych i była wyraźnie wyższa niż w przypadku procesu koagulacji.

EN

The aim of this study was to treat of tannery wastewater with the chemical advanced oxidation using Fenton reagent. Advanced oxidation process was carried out using different doses of iron (Fe2+) changes from 0.056 g Fe2+/dm3to 0.56 g Fe2+/dm3and H2O2from 0.34 g/dm3 to 5.44 g/ dm3. The wastewater samples were characterized for the concentration of chemical oxygen demand (COD), chromium, ammonia and pH, conductivity. The possibility of using the coagulation process using SAX 18 was also investigated. The efficiency of the applied processes was monitored by change mainly of chemical oxygen demand (COD). The maximum COD removal was 80% for Fenton’s oxidation process at pH 3.0, Fe2+ (0.56 g Fe2+/ dm3) and H2O2 (4.08 g/ dm3) and significantly higher than in the case of the coagulation process.

7

Utlenienie siarczków w ściekach garbarskich

Kubala A., Przywara L.

Proceedings of ECOpole

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2015

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Vol. 9, No. 1

253--259

PL

Przemysł garbarski charakteryzuje się znaczną uciążliwością dla środowiska naturalnego. Wytwarza duże ilości ścieków zawierających związki organiczne wypłukiwane ze skóry (m.in. tłuszcze i białka), różnorodne substancje nieorganiczne, w tym chrom(III), siarczki. Skład ścieków z przemysłu garbarskiego zależy od rodzaju wyprawy oraz od pochodzenia danej skóry. Obecnie wszystkie garbarnie w procesie przetwarzania skór zwierzęcych na skórę używają siarczków. Zazwyczaj jest to siarczek sodu lub wodorosiarczek sodu. Forma siarczków, w jakiej znajdują się one w ściekach, zależy od odczynu. W roztworze kwaśnym przy pH < 6 dominuje obecność H2S; przy pH ≥ 8 główną postacią są MeHS, natomiast siarczki występują przy pH ≥ 10. Związki te mogą być usuwane w procesach biologicznych, chemicznych i fizycznych. Jedną z metod usuwania siarczków ze ścieków garbarskich może być ich utlenienie. W pracy przedstawiono wyniki laboratoryjnych badań utleniania siarczków w ściekach z garbarni przy zastosowaniu siarczanu(VI) manganu(II). Przedmiotem opisywanych badań w pracy było określenie optymalnej dawki manganu i czasu utlenienia. Badania przeprowadzono przy różnym stosunku Mn:S. Zmiana w czasie zawartości siarczków w ściekach wskazuje, że reakcje chemiczne prowadzące do obniżenia parametrów mają miejsce natychmiast po dodaniu utleniacza.

EN

Tanning industry is characterized by a considerable environmental nuisance. It produces large amounts of wastewater, containing organic compounds leached from skin (eg fats and protein) as well as various inorganic substances including chromium(III), sulphides. The composition of wastewater from tanning industry depends on the type and origin of leather used. Nowadays, in the transforming process of animal skin into leather almost every tannery uses sulphides, mostly sodium sulphide and sodium hydrosulphide. The form of sulphides in effluents depends on the pH. The acidic solution (pH < 6) is dominated by the presence of H2S, while, MeHS constitutes the main form for at pH ≥ 8. Sulphides dominate at the pH ≥ 10. These compounds can be removed by biological, chemical and physical processes. The paper presents the results of laboratory studies of sulphides oxidation in the effluent from tannery wastewater, using manganese sulphate. The aim of the experiments performed was to determine the optimal dosage of manganese and the most appropriate oxidation time. The studies were conducted at various Mn:S ratios. Changes of sulphides during the oxidation time indicate that chemical reactions leading to the reduction of the parameter take place immediately after oxidizer addition.

8

Effects of pretanning effluent originated from leather industry on the germination of rice seeds

Yapici A. N., Tayyar S.

Environment Protection Engineering

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2014

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Vol. 40, nr 3

17--28

EN

The effects of pretanning effluent obtained from leather processing on the germination and seedling growth of rice were investigated. Undiluted pretanning effluents, and its 1:10, 1:40 and 1:80 dilutions along with tap water were used for irrigation to germinate the seeds. Some morphological characteristics were investigated. No germination occurred in the seeds irrigated with the undiluted pretanning effluent. Elemental analyses of the shoots and roots of rice seedlings were conducted. The lowest contents of C (29.7%), S (0.41%), Cr (1.2 mg/kg) and Na (2933.8 mg/kg) in shoots were detected in control group. The lowest contents of Cu (38.81 mg/kg) and Mn (2225.0 mg/kg) in roots were determined in irrigations with 1:10 dilutions.

9

Tannery wastewater treatment by anodic electrooxidation coupled with electro-Fenton process

Naumczyk J., Kucharska M.

Environment Protection Engineering

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2011

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Vol. 37, nr 3

47-54

EN

Investigations were performed on tannery wastewater, previously coagulated with FeCl3. An electrolyzer was equipped with two graphite cathodes and Ti/SnO2/PdO2/RuO2 anode, divided by the diaphragm made of asbestos fibre. The current density was: cathodic 2.0 A/dm2 and anodic 2.1 A/dm2. After 55 min of the process the catholyte was transferred into the anodic space and the process was continued. After 55 min of electro-Fenton process, the COD was reduced by 52.0% (current efficiency of COD removal was 10.6%). Electrooxidation continued by the anodic process resulted in elimination of ammonia in 55 min and a total reduction of COD by 72.9%. The coupled process d could be considered a simulation of the combined process under flow conditions. The effect of this process was compared to that of a two-steps process: Fenton process followed by indirect anodic oxidation.

10

Microfiltration and ultrafiltration of tannery wastewaters

Kowalik A., Kluziński W., Gierycz P.

Problemy Eksploatacji

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2009

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nr 1

135-144

EN

The article presents a new pilot scale membrane unit with microfiltration and ultrafiltration modules. The obtained results of the initial investigations confirm the applicability of the MF and UF membranes for proper removal of fats and proteins from tannery wastewaters. The composition of real tannery effluents, the results of the accomplished analyses of microfiltration and ultrafiltration and the evaluation of the possibilities of implementation of this process in a larger scale have been also presented.

PL

W artykule zaprezentowano półtechniczną instalację membranową wraz z testowanymi modułami mikro- i ultrafiltracyjnymi oraz metodykę usuwania z ich pomocą emulsji tłuszczowych i białek zwierzęcych ze ścieków garbarskich. Przedstawiony został skład przebadanych ścieków garbarskich, wyniki przeprowadzonych badań mikro- i ultrafiltracji, a także ocena możliwości i celowość zastosowania tego procesu w większej skali.

11

Ścieki garbarskie i kuśnierskie na Podhalu zarys problemu w oparciu o doświadczenia eksploatacyjne Podhalańskiego Przedsiębiorstwa Komunalnego

Szuba P.

Forum Eksploatatora

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2009

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Nr 4 (43)

44-48

PL

Podhale słynie nie tylko z pięknych widoków, stoków narciarskich i oscypków. Długą tradycję ma tu również produkcja kożuchów i innych wyrobów ze skór, zwłaszcza owczych. Produkcja ta wiąże się jednak z powstawaniem uciążliwych dla środowiska odpadów, a także ścieków garbarskich i kuśnierskich, których znaczna część odprowadzana jest nielegalnie do kanalizacji sanitarnej lub bezpośrednio do wód i gleby. Na terenie działania Podhalańskiego Przedsiębiorstwa Komunalnego Sp. z o.o. obejmującego obecnie dziesięć gmin w zlewni Dunajca, największy problem związany z tym szczególnym rodzajem ścieków przemysłowych występuje w gminie Nowy Targ. Zakłady kuśnierskie znajdują się także na terenie wsi Maniowy w gminie Czorsztyn, a także w gminie Łapsze Niżne, jednak największa ich koncentracja występuje na Podhalu. W niniejszym opracowniu nie ujęto samego miasta Nowy Targ pomimo tego, że na jego terenie znajduje się wiele zakładów branży kuśnierskiej i garbarskiej.

12

Problems with hardly biodegradable contaminants in tannery wastewater treatment

Ozonek J., Kotulska M., Piotrowicz A.

Polish Journal of Chemical Technology

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2006

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Vol. 8, nr 3

125-128

EN

The main purpose of this study was to present the application of biological fixed bed reactor in the tannery wastewater treating. Raw tannery sewages are characterized by a great concentration of ammonia nitrogen, total suspended solids (TSS), total dissolved solids (TDS) and the presence of sulphide and chromium. The chemical pretreatment does not solve the problem because it removes only part of the biological oxygen demand (BOD) and the chemical oxygen demand (COD) (65 - 85%), suspended solids, sulphide and chromium. Due to the insufficient effectiveness of the mechanical and chemical methods, a biological method has been developed. Therefore the fixed bed reactor with Terrapol®-type filling packs was used. Its operational volume of 537 m3 was divided into the denitrification chamber, nitrification chamber with the fixed bed and the multi-streams secondary settling chamber. The experimentation comprised 2 stages. The first one was carried out in the full scale during the technological starting-up of the Szczakowa tannery wastewater plant (Jaworzno, Poland), while the other one concerned some improvements of the method. With the additional use of active carbon and polyelectrolyte, the proposed biological treatment has proved its effectiveness and suitability for tannery wastewater purification.