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1

Modification of Electro-Fenton Process with Granular Activated Carbon for Phenol Degradation – Optimization by Response Surface Methodology

Thwaini Hind H., Salman Rasha H.

Journal of Ecological Engineering

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2023

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Vol. 24, nr 9

92--104

EN

As a result of rapid industrialization and population development, toxic chemicals have been introduced into water systems in recent decades. Because of its excellent efficiency and simple design, the three-dimensional (3D) electro-Fenton method has been used for the treatment of wastewater. The goal of the current study is to explore the efficiency of phenol removal by the 3D electro-Fenton process, which is one of the advanced oxidation processes (AOPs). In the present work, the effect of the addition of granular activated carbon (GAC) particles to the electro-Fenton system as the third electrode would be investigated in the presence of graphite as the anode and nickel foam as the cathode, which is the source of electro-generated hydrogen peroxide (H2O2). The influence of operation parameters (current density, electrolysis time, and GAC) on catalytic performance will be studied, which will be adjusted by the response surface methodology (RSM). The pH was adjusted to 3, and the airflow was set to 10 L/h. According to the results the nickel foam was an excellent cathode material choice. The best conditions for phenol elimination were at current density of 3.56 mA/cm2, FeSO4.7H2O dosage of 0.1 mM, GAC of 30 g, and a time of 3 h to attain the removal rates of phenol and chemical oxygen demand (COD) of 98.79% and 93.01%, respectively. The results showed that time had a higher effect on the phenol and COD removal efficiency, while the impact of current density was lower. The model equation’s high R2 value (97.90%) demonstrates its suitability.

2

Assessment of the ozonation impact on adsorption efficiency in surface water treatment

Adamski Wojciech, Wisniewski Jacek, Wolska Malgorzata

Environment Protection Engineering

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2023

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Vol. 49, nr 3

95--107

EN

Organic substances in water, both of natural and synthetic origin, especially their share in water treatment by-products can pose a threat to drinkers. That is why adsorption, as a very effective process of dissolved organic compounds removal is commonly used in surface water treatment systems. For process design and optimization, mathematical models both mechanistic and statistics are created. The results of the investigation of granular activated carbon (GAC) bed adsorption in a pilot plant with a capacity of 3 m3/h have been presented. Two systems have been tested – without ozonation and with ozonation before GAC adsorption. The models of the kinetics of GAC adsorption capacity exhaustion, the model of minimal GAC bed depth (adsorption zone) for assumed process efficiency (C/CO), as well as the model of adsorption zone movement velocity to the bottom of GAC bed, have been created. For the state of adsorptive equilibrium, the first model enables the determination of the isotherm parameters of the Freundlich type, the two other models are used for the calculation of GAC bed run time for the certain bed depth and assumed efficiency. It has been shown that in this case (water pollution, GAC type, pretreatment) ozonation plays a minor role.

3

Environmental Assessment of a Unique Filtration Process for Treatment of Polluted Storm Water

Al-Khalaf Safaa K. Hashim, Al-Ridah Zaid Abed, Shlash Marwah Abdullah, Naje Ahmed Samir

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 1

116--124

EN

As a result of poor human activities, storm water is now contaminated, notably in the Middle East. The filtering process is a physical separation with no chemical reactions occurring throughout the operation. The goal of this research is to use three distinct types of filters to improve the quality of storm water: sand, sand with granular activated carbon (GAC), and sand with cotton. Before and after treatment, the pH, turbidity, electric conductivity, TDS, and temperature of storm water are all monitored. In addition, the water quality index (WQI) was computed. The parameters of treated storm water varied depending on the filter media used, such as sand (turbidity = 83 NTU, TDS = 585 mg/L, conductivity = 1190 S/cm, pH = 7.1 and temperature =17.8 °C), sand with GAC (turbidity = 12NTU, TDS = 540 mg/L, conductivity = 910 S/cm, pH = 7 and temperature =18 °C) and sand with cotton (turbidity = 6.4 NTU, TDS = 490 mg/L, conductivity = 1090 μS/cm, pH = 7.2 and temperature =17.6 °C). Sand has a treatment efficiency of 63.6 percent, sand with GAC has an efficiency of 84.9 percent, and sand with cotton has an efficiency of 84.2 percent at a flow rate of 0.66 L/min, when WQI is clean. With GAC, it is clear that the dual media filter is the finest special sand.

4

Adsorption of n-hexane on a low-cost adsorbent obtained from waste tyres and its microwave regeneration

Kotkowski Tomasz, Cherbański Robert, Molga Eugeniusz

Chemical and Process Engineering

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2022

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Vol. 43, nr 1

57–-80

EN

This work investigates adsorption of n-hexane on activated tyre pyrolysis char (ATPC) and granular activated carbon (GAC) as a reference material in a fixed-bed column. Microwave-assisted regeneration is also considered. The adsorbed amount of n-hexane on ATPC is in the range of 37–58 mg/g. Microwave-assisted desorption of ATPC samples enables the recovery of up to 95% of adsorbed n-hexane in this non-optimized microwave setup with the efficiency of microwave energy conversion into heat of only 5–6%. For the 50% breakthrough time, ATPC and GAC are able to purify the n-hexane gas volumes in the ranges of 20–90 and 935–1240 cm3/g, respectively. While adsorption kinetics is not satisfactorily described by pseudo-first and pseudo-second order kinetic models, it is very well reflected by a family of dynamic adsorption models, which are modelled with a single logistic function. Internal diffusion is likely the rate limiting step during adsorption on ATPC, while external and internal diffusion likely plays a role in adsorption to GAC. Although microwave-assisted regeneration is performed in a general purpose microwave reactor, both adsorbents show excellent performance and are very good candidates for the adsorption process. Preliminary results show that magnetite can further reduce microwave energy consumption.

5

Filtry piaskowe po granulowanym węglu aktywnym

Dąbrowski W.

Instal

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2017

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nr 12

49--53

PL

Przedstawiono przegląd literatury, z którego wynika celowość stosowania pospiesznych filtrów piaskowych za złożami granulowanego węgla aktywnego. Powodem lokalizowania filtrów piaskowych za GAC jest ochrona wody do picia przed pyłem węglowym zawierającym mikroorganizmy. Bakterie schowane w porach małych cząstek są odporne na dezynfekcję. Przedstawiono przykłady zastosowania.

EN

A literature review has been presented about the necessity of applying rapid sand filters after granular activated carbon used as an adsorbent in water treatment plants. The purpose of locating the sand filters after GAC is to protect drinking water against fine coal particles including microorganisms. The bacteria hidden in the pores of fine particles are resistant to disinfectants. Some cases of applications have been described.

6

The use of activated carbons for removing organic matter from groundwater

Kaleta J., Kida M., Koszelnik P., Papciak D., Puszkarewicz A., Tchórzewska-Cieślak B.

Archives of Environmental Protection

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2017

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Vol. 43, no. 3

32--41

EN

The article presents research results of the introduction of powdery activated carbon to the existing technological system of the groundwater treatment stations in a laboratory, pilot plant and technical scale. The aim of the research was to reduce the content of organic compounds found in the treated water, which create toxic organic chlorine compounds (THM) after disinfection with chlorine. Nine types of powdery active carbons were tested in laboratory scale. The top two were selected for further study. Pilot plant scale research was carried out for the filter model using CWZ-30 and Norit Sa Super carbon. Reduction of the organic matter in relation to the existing content in the treated water reached about 30%. Research in technical scale using CWZ-30 carbon showed a lesser efficiency with respect to laboratory and pilot-plant scale studies. The organic matter decreased by 15%. Since filtration is the last process before the individual disinfection, an alternative solution is proposed, i.e. the second stage of filtration with a granular activated carbon bed, operating in combined sorption and biodegradation processes. The results of tests carried out in pilot scale were fully satisfactory with the effectiveness of 70–100%.

PL

W artykule przedstawiono wyniki badań w skali laboratoryjnej, półtechnicznej i technicznej nad wprowadzeniem do istniejącego układu technologicznego stacji uzdatniania wody podziemnej, pylistego węgla aktywnego. Celem badań było obniżenie zawartości występujących w wodzie uzdatnionej związków organicznych, które po procesie dezynfekcji chlorem tworzą toksyczne związki chloroorganiczne (THM). W skali laboratoryjnej przebadano 9 rodzajów pylistych węgli aktywnych, z których dwa najlepsze wytypowano do dalszych badań. Badania w skali półtechnicznej realizowano na filtrze modelowym z zastosowaniem węgli: CWZ-30 i Norit Sa Super. Obniżenie materii organicznej w stosunku do jej dotychczasowej zawartości w wodzie uzdatnionej wynosiło ok.30%. Badania w skali technicznej z zastosowaniem węgla CWZ-30 wykazały nieco mniejszą skuteczność w odniesieniu do badań laboratoryjnych i badań w skali półtechnicznej. Obniżenie zawartości materii organicznej wyniosło ok. 15%. Ponieważ ostatnim procesem jednostkowym przed dezynfekcją jest filtracja, zaproponowano alternatywne rozwiązanie – drugi stopień filtracji ze złożem granulowanego węgla aktywnego, pracującego w połączonych procesach sorpcji i biodegradacji. Rezultaty badań zrealizowanych w skali półtechnicznej były w pełni zadowalające – skuteczność 70–100%.

7

Effect of TiO2-ZnO/GAC on by-product distribution of CVOCs decomposition in a NTP-assisted catalysis system

Abed K., Ghorbani-Shahna F., Bahrami A., Jaleh B., Yarahmadi R.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 1

32--40

EN

In this study, the catalytic effect of TiO2-ZnO/GAC coupled with non-thermal plasma was investigated on the byproducts distribution of decomposition of chlorinated VOCs in gas streams. The effect of specific input energy, and initial gas composition was examined in a corona discharge reactor energized by a high frequency pulsed power supply. Detected by-products for catalytic NTP at 750 J L-1 included CO, CO2, Cl2, trichloroacetaldehyde, as well as trichlorobenzaldehyde with chloroform feeding, while they were dominated by CO, CO2, and lower abundance of trichlorobenzaldehyde and Cl2 with chlorobenzene introduction. Some of the by-products such as O2, NO, NO2, and COCl2 &enspdisappeared totally over TiO2-ZnO/GAC. Furthermore, the amount of heavy products such as trichlorobenzaldehyde decreased significantly in favor of small molecules such as CO, CO2, and Cl2 with the hybrid process. The selectivity towards COx soared up to 77% over the catalyst at 750 J L-1 and 100 ppm of chlorobenzene.

8

Usuwanie bromków i bromianów z wody w procesie wymiany anionów przez membranę jonowymienną

Wiśniewski J. A., Kabsch-Korbutowicz M., Łakomska S.

Rocznik Ochrona Środowiska

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2013

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Tom 15, cz. 2

1260--1273

EN

Bromide ions are present both in surface and ground water and their concentration ranges from several to 800 µg/L. Bromides are not reported to be detrimental to human health but their presence in the water being disinfected is a contributing factor in the formation of harmful disinfection by-products (DBP). During water disinfection with chlorine, bromides are oxidized to hypobromous acid (HOBr), which reacts with natural organic matter (NOM) to form carcinogenic brominated trihalomethanes (BrTHM). When ozone is used in water disinfection, bromides are oxidized to hypobromite ions (OBr-/) and thereafter to bromates (BrO3-). Bromates are ions exerting a carcinogenic effect on human organisms. According to the data published by the US Environmental Protection Agency, the lifetime risk of cancer disease amounts to 10-4, for a man consuming daily 2 L of water containing 5 μg BrO3-/L. The above data prove that bromides or bromates should be removed from drinking water. Among the methods used for this purpose, coagulation (for bromide removal) and granular activated carbon adsorption or reverse osmosis (for bromate removal) provide the highest removal efficiency. We proposed Donnan dialysis with anion-exchange membrane for removal of bromides or bromates from water. In this process, an anion-exchange membrane separates two solutions: the feeding solution (with harmful anions) and the receiver (with a simple salt of a relatively high concentration). Transport of the driving anions (e.g. chlorides) from the receiver to the feeding solution induces an equivalent, oppositely directed anion flow to the receiver. In this way the harmful anions that occur in the solution being treated (bromides or bromates) are replaced with neutral ions from the receiver (i.e. chlorides). Donnan dialysis was performed in a laboratory dialytic set-up containing 20 cell pairs with anion-exchange membranes, Selemion AMV (Asahi Glass) or Neosepta ACS (Tokuyama Corp.). The working area of the membranes amounted to 0.140 m2. The feed was natural water enriched with bromide salt (500 µg Br-/L) or with bromate salt (50 µg BrO3-/L). The receiver was NaCl solution with concentration ranging from 50 to 300 mM. It was found that Donnan dialysis with the anion-exchange membrane Selemion AMV enables high removal efficiency of bromides from natural water containing 500 µg Br-/L. The efficiency of bromide removal amounts to 86% at a relatively low NaCl concentration in the receiver (100 mM). The exchange of bromide ions for chloride ions is paralleled by the exchange of associated anions: sulphates (with 76% efficiency) and bicarbonates (with 70% efficiency). Compared to the anion-exchange process with Selemion AMV, the process involving Neosepta ACS (an anion-exchange membrane of a compact surface structure) provides a higher efficiency of bromide removal that amounts to 90%. In this process, retention of the associated anions is relatively high: sulphates are exchanged for chlorides with the efficiency of 3% and bicarbonates – with the efficiency of 43%. The anion-exchange process with the membrane Selemion AMV offers complete removal of bromates from natural water (containing 50 µg BrO3-/L), when salt concentration in the receiver is low (100 mM NaCl). There is aconcomitant exchange of other anions for chloride ions: sulphates are exchanged for chlorides with the efficiency of 93% and bicarbonates – with the efficiency of 73%. The anion-exchange process also provides complete removal of bromates from natural water, when use is made of the Neosepta ACS membrane. However, the exchange of sulphate ions and bicarbonate ions for chloride ions is poor (3% efficiency and 47% efficiency, respectively). Such treatment approach may be recommended for implementation, when the concentration of anions (especially that of bicarbonates) in the water to be treated is low.