State of the Art of UV/Chlorine Advanced Oxidation Processes: Their Mechanism, Byproducts Formation, Process Variation, and Applications

Kishimoto, Naoyuki

doi:10.2965/jwet.19-021

Cited by 53 publications

(30 citation statements)

References 138 publications

(300 reference statements)

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“…On the other hand radical scavenger effects of HOCl and ClOmay result in additional chlorine degradation and the formation of oxy-chlorine radicals. Such scavenger effects are stronger at basic pH [29].…”

Section: Lab Testmentioning

confidence: 93%

“…Annually on average 15 g of pharmaceuticals are consumed per capita, but human bodies are unable to fully metabolize pharmaceuticals, which are then excreted as parental components or metabolites [1,2]. They are discharged into wastewater together with Personal Care Products The RCS coexist with •OH radicals and complement each other in degrading a wider variety of contaminants compared to e.g., UV/H 2 O 2 AOP [29,30]. Depending on the chlorine species present two reaction pathways (Equations (1)-(3)) for the production of •OH and •Cl exist [26].…”

Section: Introductionmentioning

confidence: 99%

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Oxidation of Selected Trace Organic Compounds through the Combination of Inline Electro-Chlorination with UV Radiation (UV/ECl2) as Alternative AOP for Decentralized Drinking Water Treatment

Otter

Mette²,

Wesch³

et al. 2020

Water

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A large variety of Advanced Oxidation Processes (AOPs) to degrade trace organic compounds during water treatment have been studied on a lab scale in the past. This paper presents the combination of inline electrolytic chlorine generation (ECl2) with low pressure UV reactors (UV/ECl2) in order to allow the operation of a chlorine-based AOP without the need for any chlorine dosing. Lab studies showed that from a Free Available Chlorine (FAC) concentration range between 1 and 18 mg/L produced by ECl2 up to 84% can be photolyzed to form, among others, hydroxyl radicals (OH) with an UV energy input of 0.48 kWh/m3. This ratio could be increased to 97% by doubling the UV energy input to 0.96 kWh/m3 and was constant throughout the tested FAC range. Also the achieved radical yield of 64% did not change along the given FAC concentration range and no dependence between pH 6 and pH 8 could be found, largely simplifying the operation of a pilot scale system in drinking water treatment. Whereas with ECl2 alone only 5% of benzotriazoles could be degraded, the combination with UV improved the degradation to 89%. Similar results were achieved for 4-methylbenzotriazole, 5-methylbenzotriazole and iomeprol. Oxipurinol and gabapentin were readily degraded by ECl2 alone. The trihalomethanes values were maintained below the Germany drinking water standard of 50 µg/L, provided residual chlorine concentrations are kept within the permissible limits. The here presented treatment approach is promising for decentralized treatment application but requires further optimization in order to reduce its energy requirements.

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Section: Lab Testmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Oxidation of Selected Trace Organic Compounds through the Combination of Inline Electro-Chlorination with UV Radiation (UV/ECl2) as Alternative AOP for Decentralized Drinking Water Treatment

Otter

Mette²,

Wesch³

et al. 2020

Water

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“…Consequently, the secondary wastewater effluents of conventional activated sludge treatment still contain numerous MPs. In order to abate the presence of these compounds, advanced oxidation processes such as (i) UV/H 2 O 2 [220], UV/chlorine [221] and/or ozonebased applications (O 3 /H 2 O 2 and O 3 /UV) [222], and (ii) photo Fenton processes [223] and various electro-catalytic processes [224] are applied (or tested at pilot scale). Hence, the AOPs are found to fill the gap between the conventional physico-chemical and biological treatments and the limits set by environmental regulations (i.e., the degree of contamination of the treated wastewater determined by its end/use or site of discharge) [225].…”

Section: In-and Outputsmentioning

confidence: 99%

Nature-Based Units as Building Blocks for Resource Recovery Systems in Cities

Hullebusch

Bani

Carvalho³

et al. 2021

Water

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Cities are producers of high quantities of secondary liquid and solid streams that are still poorly utilized within urban systems. In order to tackle this issue, there has been an ever-growing push for more efficient resource management and waste prevention in urban areas, following the concept of a circular economy. This review paper provides a characterization of urban solid and liquid resource flows (including water, nutrients, metals, potential energy, and organics), which pass through selected nature-based solutions (NBS) and supporting units (SU), expanding on that characterization through the study of existing cases. In particular, this paper presents the currently implemented NBS units for resource recovery, the applicable solid and liquid urban waste streams and the SU dedicated to increasing the quality and minimizing hazards of specific streams at the source level (e.g., concentrated fertilizers, disinfected recovered products). The recovery efficiency of systems, where NBS and SU are combined, operated at a micro- or meso-scale and applied at technology readiness levels higher than 5, is reviewed. The importance of collection and transport infrastructure, treatment and recovery technology, and (urban) agricultural or urban green reuse on the quantity and quality of input and output materials are discussed, also regarding the current main circularity and application challenges.

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“…ClO 3 − is produced through the self-decomposition of free chlorine (reactions ( 25) and ( 26)) and radical reactions initiated by ClO˙ [2]. The optimal pH for reaction (25) was reported to be 7.24, and reaction ( 26) is favorable in basic conditions [27].…”

Section: Von Gunten and Oliverasmentioning

confidence: 99%

“…Recently, these photochemical reactions have been applied in the water treatment field as an advanced oxidation process called the "UV/chlorine process". The number of published papers on UV/chlorine processes has grown rapidly in the last several years [2]. As chlorination and UV treatment are widely used in the water treatment field, technical bases for unit operations constituting UV/chlorine process have been established.…”

Section: Introductionmentioning

confidence: 99%

Availability of Seawater as A Chloride Source for UV/electro-chlorine Advanced Oxidation Process

Kishimoto

Hara

2021

J. of Wat. & Envir. Tech.

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This study reports the availability of seawater as an economical chloride (Cl − ) source for the UV/ electro-chlorine process from the viewpoints of advanced oxidation performance and unwanted byproduct formation of chlorate ion (ClO 3 − ) and bromate ion (BrO 3 − ). In the electrochemical oxidant production stage, the oxidant production rate in diluted seawater containing 30 mM Cl − was 21% lower than that in the NaCl solution due to coexisting electrolytes in the seawater. The ClO 3 − formation during electrolysis was successfully inhibited under acidic conditions and BrO 3 − formation was not detected in the diluted seawater. However, ClO 3 − and BrO 3 − were steadily formed in the undiluted seawater electrolysis, even when the initial pH value was set to 3. The oxidant utilization efficiency for 1,4-dioxane removal during UV irradiation was not deteriorated in the diluted seawater but decreased under basic conditions due to the radical scavenging effect of electrochemically produced free bromine and free chlorine. As a result, the formation of BrO 3 − and ClO 3 − was enhanced under basic conditions, whereas BrO 3 − formation was completely inhibited at an initial pH ≤ 5. Consequently, the diluted seawater was thought to be available as a Cl − source for the UV/electro-chlorine process if an acidic condition was maintained throughout the operation.

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State of the Art of UV/Chlorine Advanced Oxidation Processes: Their Mechanism, Byproducts Formation, Process Variation, and Applications

Cited by 53 publications

References 138 publications

Oxidation of Selected Trace Organic Compounds through the Combination of Inline Electro-Chlorination with UV Radiation (UV/ECl2) as Alternative AOP for Decentralized Drinking Water Treatment

Oxidation of Selected Trace Organic Compounds through the Combination of Inline Electro-Chlorination with UV Radiation (UV/ECl2) as Alternative AOP for Decentralized Drinking Water Treatment

Nature-Based Units as Building Blocks for Resource Recovery Systems in Cities

Availability of Seawater as A Chloride Source for UV/electro-chlorine Advanced Oxidation Process

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