A Study on the Formation of Free Residual Chlorine by Electrolysis Reaction for Drinking Water Treatment

Many countries require the presence of free chlorine at about 0.1 mg/l in their drinking water supplies. For various reasons, such as cast-iron pipes or long residence times in the distribution system, free chlorine may decrease below detection limits. In such cases it is important to know whether or not the water was chlorinated or if nonchlorinated water entered the system by accident. Changes in UV spectra of natural organic matter in lakewater were used to assess qualitatively the degree of chlorination in the treatment to produce drinking water. The changes were more obvious in the first derivative spectra. In lakewater, the derivative spectra have a maximum at about 280 nm. This maximum shifts to longer wavelengths by up to 10 nm, decreases, and eventually disappears with an increasing dose of chlorine. The water treatment system was monitored by this technique for over 1 year and changes in the UV spectra of water samples were compared with experimental samples treated with known amounts of chlorine. The changes of the UV spectra with the concentration of added chlorine are presented. On several occasions, water, which received very little or no chlorination, may have entered the drinking water system. The results show that first derivative spectra are potentially a tool to determine, in the absence of residual chlorine, whether or not surface water was chlorinated during the treatment to produce potable water.

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After the flood: an evaluation of in-home drinking water treatment with combined flocculent-disinfectant following Tropical Storm Jeanne — Gonaives, Haiti, 2004

Journal of Water and Health ◽

10.2166/wh.2007.032 ◽

2007 ◽

Vol 5 (3) ◽

pp. 367-374 ◽

Cited By ~ 44

Author(s):

Romulo E. Colindres ◽

Seema Jain ◽

Anna Bowen ◽

Eric Mintz ◽

Polyana Domond

Keyword(s):

Drinking Water ◽

Water Treatment ◽

Drinking Water Treatment ◽

Water Sources ◽

Tropical Storm ◽

Coliform Bacteria ◽

Residual Chlorine ◽

Household Water ◽

Untreated Water ◽

Local Leaders

Tropical Storm Jeanne struck Haiti in September 2004, causing widespread flooding which contaminated water sources, displaced thousands of families and killed approximately 2,800 people. Local leaders distributed PūR®, a flocculent-disinfectant product for household water treatment, to affected populations. We evaluated knowledge, attitudes, practices, and drinking water quality among a sample of PūR® recipients. We interviewed representatives of 100 households in three rural communities who received PūR® and PūR®-related education. Water sources were tested for fecal contamination and turbidity; stored household water was tested for residual chlorine. All households relied on untreated water sources (springs [66%], wells [15%], community taps [13%], and rivers [6%]). After distribution, PūR® was the most common in-home treatment method (58%) followed by chlorination (30%), plant-based flocculation (6%), boiling (5%), and filtration (1%). Seventy-eight percent of respondents correctly answered five questions about how to use PūR®; 81% reported PūR® easy to use; and 97% reported that PūR®-treated water appears, tastes, and smells better than untreated water. Although water sources tested appeared clear, fecal coliform bacteria were detected in all sources (range 1 – >200 cfu/100 ml). Chlorine was present in 10 (45%) of 22 stored drinking water samples in households using PūR®. PūR® was well-accepted and properly used in remote communities where local leaders helped with distribution and education. This highly effective water purification method can help protect disaster-affected communities from waterborne disease.

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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

Water ◽

10.3390/w12113275 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3275

Author(s):

Philipp Otter ◽

Katharina Mette ◽

Robert Wesch ◽

Tobias Gerhardt ◽

Frank-Marc Krüger ◽

...

Keyword(s):

Drinking Water ◽

Water Treatment ◽

Organic Compounds ◽

Energy Input ◽

Drinking Water Treatment ◽

Pilot Scale ◽

Residual Chlorine ◽

Trace Organic Compounds ◽

Drinking Water Standard ◽

Trace Organic

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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Behavior of Musty Odorous Compounds during the Process of Water Treatment

Water Science & Technology ◽

10.2166/wst.1988.0251 ◽

1988 ◽

Vol 20 (8-9) ◽

pp. 261-267 ◽

Cited By ~ 20

Author(s):

K. Ashitani ◽

Y. Hishida ◽

K. Fujiwara

Keyword(s):

Drinking Water ◽

Water Treatment ◽

Pilot Plant ◽

Residual Chlorine ◽

Raw Water ◽

Undetectable Level ◽

Sand Filter ◽

Musty Odor ◽

Free Residual Chlorine ◽

Suspended Form

Geosmin and 2-methylisoborneol (MIB) are two of the causative compounds responsible for the musty odor problem in drinking water. Geosmin and MIB in raw water were present both in solution and in a suspended form mostly associated with the host cyanobacteria. Geosmin and MIB in suspended form were well removed by coagulation and sedimentation alone. Geosmin present in solution could be removed almost to an undetectable level in the rapid sand filter of the pilot plant where no pre-chlorination was practiced. Breakpoint pre-chlorination, however, forced geosmin and MIB present inside of the host algae to leak into the water. The concentration of MIB decreased in a sedimentation basin during the daytime, but not at night in the plant practicing breakpoint pre-chlorination. Geosmin and MIB were both decomposed under sunlight in the presence of free residual chlorine.

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Enhancement of the free residual chlorine concentration at the ends of the water supply network: Case study of Souk Ahras city – Algeria

Journal of Water and Land Development ◽

10.2478/jwld-2018-0036 ◽

2018 ◽

Vol 38 (1) ◽

pp. 3-9 ◽

Cited By ~ 3

Author(s):

Mohamed A. Bensoltane ◽

Lotfi Zeghadnia ◽

Lakhdar Djemili ◽

Abdalhak Gheid ◽

Yassine Djebbar

Keyword(s):

Drinking Water ◽

Water Supply ◽

Distribution Systems ◽

Drinking Water Treatment ◽

Field Measurements ◽

Residual Chlorine ◽

Water Utility ◽

The Public ◽

Point Of Use ◽

Free Residual Chlorine

AbstractThe drinking-water supply sector has mostly targeted the water-borne transmission of pathogens. The most common method employed is the chlorination of drinking-water at treatment plants and in the distribution systems. In Algeria, the use of chlorine in drinking water treatment is a widespread practice. To enhance the concentration of the residual chlorine in the public water-supply system of a part of Souk Ahras city (Faubourg) (Algeria) known by its low concentration of the free residual chlorine (according to the water utility – Algérienne des Eaux: ADE investigation) especially at the point of use, practical steps were carried out. The method is a combination between numerical simulation using EPANET2 software and field measurements. Using statistical analysis the hydraulic model was calibrated and the observed values were very closer to the simulated results. The concentration was improved throughout the network after the injection of the appropriate dose.

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Pilot plant study on ozonation and biological activated carbon process for drinking water treatment

Water Science & Technology ◽

10.2166/wst.1997.0293 ◽

1997 ◽

Vol 35 (8) ◽

pp. 21-28 ◽

Cited By ~ 10

Author(s):

Woo Hang Kim ◽

Wataru Nishijima ◽

Eiji Shoto ◽

Mitsumasa Okada

Keyword(s):

Drinking Water ◽

Activated Carbon ◽

Water Treatment ◽

Contact Time ◽

Drinking Water Treatment ◽

Suspended Solid ◽

Residual Chlorine ◽

Raw Water ◽

Activated Carbon Adsorption ◽

Biological Activated Carbon

A study on advanced drinking water treatment was conducted in a pilot scale plant taking raw water from Minaga Reservoir, Japan. Ozonation-biological activated carbon process (O3-BAC), BAC process (BAC) and chlorination-granular activated carbon adsorption process (Cl2-GAC) were evaluated based on the following parameters; dissolved organic carbon (DOC), adsorbable DOC (ADOC) and biodegradable DOC (BDOC). The raw water used was pre-treated by biofiltration for suspended solid removal and biological treatment. Contact time for ozonation and chlorination was 24 min. Empty bed contact time of activated carbon column was 15 min. Ozone dosage was 3 mg • 1−1. Chlorination was carried out to maintain a residual chlorine concentration of 0.2 mg • 1−1. Effluent DOC from biofiltration consisted of mainly ADOC (90%) and BDOC (10%). Therefore, DOC was mainly removed by adsorption in all processes. However, biodegradable DOC increased by 20% after ozonation in O3-BAC and was removed effectively by the attached bacteria on the activated carbon. Significant differences in DOC removal were not noted among the three processes during 8 months of operation. After the saturation of activated carbon, the effluent DOC from the O3-BAC was lower than that from BAC and Cl2-GAC. Ozonation improved biodegradability of organic substances and effluent water quality by the following biodegradation of biodegradable DOC by biological activated carbon.

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