Photocatalytic removal of taste and odour compounds for drinking water treatment

2009 ◽  
Vol 9 (5) ◽  
pp. 477-483 ◽  
Author(s):  
H. Tran ◽  
G. M. Evans ◽  
Y. Yan ◽  
A. V. Nguyen
Keyword(s):  
Drinking Water ◽  
Sodium Bicarbonate ◽  
Photocatalytic Degradation ◽  
Rate Constants ◽  
Degradation Rate ◽  
Degradation Mechanism ◽  
Drinking Water Treatment ◽  
Degradation Process ◽  
Negative Effects ◽  
Reaction Rate Constants

Photocatalytic degradation of geosmin and 2-methylisoborneol (MIB), which are two taste and odour compounds commonly found in drinking water supply sources, was investigated using an immobilised TiO2 photoreactor. It was found that the degradation of geosmin and MIB followed similar pseudo-first-order kinetics with reaction rate constants being approximately 0.025 min−1 for typical geosmin and MIB concentrations of 250 and 500 ng/L. The normalised formal quantum efficiency was calculated to be in the range of 162–182 L/mol. Influence of additives (i.e. sodium bicarbonate and alcohols) on the degradation process was also investigated. It was found that there was a small reduction in the degradation rate constants of geosmin and MIB with increasing sodium bicarbonate concentration. At 50 mg/L sodium bicarbonate the degradation rate constants decreased by approximately 5%. Similarly, for methanol and ethanol concentrations up to 35 and 50 mg/L, respectively, these constants were found to also decrease. While addition of sodium bicarbonate and alcohols was seen to have relatively small negative effects on the photocatalytic degradation performance, the magnitude of their influence was consistent with the hypothesis that the degradation mechanism of geosmin and MIB was predominately that of attack involving HO∙ radicals.

scholarly journals Cometabolism of Trihalomethanes by Nitrosomonas europaea

2005 ◽  
Vol 71 (12) ◽  
pp. 7980-7986 ◽  
Author(s):  
David G. Wahman ◽  
Lynn E. Katz ◽  
Gerald E. Speitel
Keyword(s):  
Drinking Water ◽  
Rate Constants ◽  
Degradation Kinetics ◽  
Drinking Water Treatment ◽  
Nitrosomonas Europaea ◽  
Ammonia Nitrogen ◽  
Degradation Rates ◽  
Ammonia Oxidizing Bacterium ◽  
Treated Drinking Water ◽  
Bromine Substitution

ABSTRACT The ammonia-oxidizing bacterium Nitrosomonas europaea (ATCC 19718) was shown to degrade low concentrations (50 to 800 μg/liter) of the four trihalomethanes (trichloromethane [TCM], or chloroform; bromodichloromethane [BDCM]; dibromochloromethane [DBCM]; and tribromomethane [TBM], or bromoform) commonly found in treated drinking water. Individual trihalomethane (THM) rate constants ( \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(k_{1_{THM}}\) \end{document} ) increased with increasing THM bromine substitution, with TBM > DBCM > BDCM > TCM (0.23, 0.20, 0.15, and 0.10 liters/mg/day, respectively). Degradation kinetics were best described by a reductant model that accounted for two limiting reactants, THMs and ammonia-nitrogen (NH3-N). A decrease in the temperature resulted in a decrease in both ammonia and THM degradation rates with ammonia rates affected to a greater extent than THM degradation rates. Similarly to the THM degradation rates, product toxicity, measured by transformation capacity (Tc ), increased with increasing THM bromine substitution. Because both the rate constants and product toxicities increase with increasing THM bromine substitution, a water's THM speciation will be an important consideration for process implementation during drinking water treatment. Even though a given water sample may be kinetically favored based on THM speciation, the resulting THM product toxicity may not allow stable treatment process performance.

Modeling lifetime and degradability of organic compounds in air, soil, and water systems (IUPAC Technical Report)

2001 ◽  
Vol 73 (8) ◽  
pp. 1331-1348 ◽  
Author(s):  
A. Sabljic ◽  
W. Peijnenburg
Keyword(s):  
Organic Compounds ◽  
Rate Constants ◽  
Reaction Rate ◽  
Evaluation Studies ◽  
Direct Calculation ◽  
Degradation Process ◽  
Evaluation Procedure ◽  
Reaction Rate Constants ◽  
Extensive Evaluation ◽  
Soil And Water

Degradability of organic compounds in air, soil, and water is the most important factor for evaluating their environment fate as well as possible adverse effects to humans and the environment. The primary degradation process in the troposphere is the reaction with the hydroxyl radical. For water and soil compartments, the primary degradation process is biodegradation. The objectives of this report are: (i) to review published models and their evaluation studies, (ii) to perform an in-house evaluation of general models for estimating tropospheric degradation and biodegradation of organic compounds, and (iii) to recommend reliable procedures for estimating degradability of organic compounds in the environment. The extensive evaluation procedure has shown that the most accurate method for estimating tropospheric degradation is Atkinson's group contribution method. Although this method has some limitations, it seems to be a method of choice. A viable alternative to Atkinson's method is a direct calculation, performed today almost routinely, of the reaction rate constants with hydroxyl radicals. Recently, a methodology based on reliable semiempirical potential energy surfaces was developed that enables the calculation of reaction rate constants within a factor of 2 of their measured values. A partial least squares (PLS) model and a set of seven biodegradation rules have been found to be the most reliable in estimating complete biodegradation of organic compounds. However, it is recommended to use all four evaluated methods to estimate biodegradation in the environment. If their results agree, such estimates are very reliable.

scholarly journals Use of an Ultraviolet Light activated Persulfate Process to Degrade Humic Substances: Effects of Wavelength and Persulfate Dose

2021 ◽  
Author(s):  
Yiming Fang ◽  
Hiroshi Sakai
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Weight ◽  
Drinking Water ◽  
Humic Substances ◽  
Degradation Mechanism ◽  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Lower Molecular Weight ◽  
High Concentration ◽  
Activated Persulfate

Abstract Natural organic matter (NOM), commonly found in surface and ground waters, form Disinfection by-products in drinking water. Generally, advanced oxidation processes (AOPs) featuring hydrogen peroxide are used to treat water, however, sulfate radical recently has been used to treat recalcitrant organics, because it is associated with a higher oxidation potential and more effective removal than hydroxyl radicals. Hence, in this research, we evaluated persulfate oxidation efficiency in terms of reductions in humic substances levels and investigated the degradation mechanism. The results showed that ultraviolet activated persulfate effectively treated humic substances compared with hydrogen peroxide and direct irradiation. Treatment was dose- and wavelength-dependent; higher persulfate concentrations or shorter UV wavelengths were more effective for treating humic substances as high concentration sulfate radicals were created. The degradation mechanism was similar to that of hydrogen peroxide. Aromatic and chromophore components were more susceptible to degradation than were lower molecular weight components, being initially decomposed into the latter, reducing UV254 absorbance and the SUVA254. Lower molecular weight materials were eventually degraded to end products: NPOC levels fell. And we also treated the inflow of a drinking water treatment plant with persulfate, and humic substances were effectively removed.

scholarly journals DRINKING WATER POLLUTION IN INDIA - A CHALLENGE FOR HUMAN HEALTH

2015 ◽  
Vol 3 (9SE) ◽  
pp. 1-5
Author(s):  
Anjana Jain
Keyword(s):  
Drinking Water ◽  
Drinking Water Treatment ◽  
World Health ◽  
Polluted Water ◽  
Negative Effects ◽  
The Public ◽  
Main Challenge ◽  
The World ◽  
The Government ◽  
Health Organization

According to the latest report of the World Health Organization, 7 lakh 83 thousand people die due to polluted water every year in India. The main challenge of the Government of India is to provide clean water to the public. Therefore, in the study presented, an attempt has been made to know why there is pollution of drinking water, what types of diseases are caused by this polluted water, d. An attempt has been made to know its negative effects and pure drinking water treatment. The data and facts have been compiled on a secondary basis. विष्व स्वास्थ संगठन की ताजा रिपोर्ट के अनुसार भारत में प्रतिवर्ष 7 लाख 83 हजार लोग प्रदूषित जल की वजह से मरते है। जनता को साफ पानी पहुचाना भारत सरकार की मुख्य चुनौति है। अतः प्रस्तुत अध्ययन में यह जानने का प्रयास किया गया है कि पेयजल प्रदुषण क्यों होता है घ् इस प्रदूषित जल से किस प्रकार की बीमारियाँ उत्पन्न होती है घ् इसके नकारात्मक प्रभाव एवं शुध्द पेयजल उपचार को जानने का प्रयास किया गया है। आंकड़ो व तथ्यों का संकलन द्वितीयक आधार पर किया गया है।

scholarly journals Do low-cost ceramic water filters improve water security in rural South Africa?

2016 ◽  
Author(s):  
Jens Lange ◽  
Tineke Materne ◽  
Jörg Grüner
Keyword(s):  
South Africa ◽  
Drinking Water ◽  
Produced Water ◽  
Low Cost ◽  
Drinking Water Treatment ◽  
Water Security ◽  
Water Source ◽  
High Water ◽  
Repeated Loading ◽  
Negative Effects

Abstract. This study examines the performance of a low-cost ceramic candle filter system (CCFS) for point of use (POU) drinking water treatment in the village of Hobeni, Eastern Cape Province, South Africa. A stepwise laboratory test documented the negative effects of repeated loading and ambient field temperatures. Moreover, CCFS were distributed in Hobeni and a survey was carried out among their users. The performance of 51 CCFS was evaluated by dip slides and related to human factors. Already after two thirds of their specified lifetime, none of the distributed CCFS produced water without distinct contamination and more than one third even deteriorated hygienic water quality. Besides the water source (springs were preferable compared to river or rain water), a high water throughput was the dominant reason for poor CCFS performance. These findings suggest that not every CCFS type per se guarantees improved drinking water security and that the efficiency of low-cost systems should continuously be monitored. For this purpose, dip slides were found to be a cost-efficient alternative to standard laboratory tests. They consistently underestimated microbial counts but can be used by laypersons and hence by the users themselves to assess critical contamination of their filter systems.

The atmospheric chemical reaction of 4-tert-butylphenol initiated by OH radicals

2013 ◽  
Vol 10 (2) ◽  
pp. 111 ◽  
Author(s):  
Chen Gong ◽  
Xiaomin Sun ◽  
Chenxi Zhang
Keyword(s):  
Rate Constants ◽  
Degradation Mechanism ◽  
Degradation Process ◽  
State Theory ◽  
Oh Radicals ◽  
Atmospheric Lifetime ◽  
Computational Theory ◽  
Developmental Problems ◽  
First Order ◽  
First Order Kinetics

Environmental context 4-tert-Butylphenol, an environmental endocrine disruptor, can be taken in by humans and animals resulting in reproductive and developmental problems. We report a theoretical study on the degradation mechanism of 4-tert-butylphenol in the atmosphere, and calculate the atmospheric lifetime of this chemical. The data will help our understanding of the behaviour of 4-tert-butylphenol in the environment and thereby provide valuable information about its possible effect on human health. Abstract 4-tert-Butylphenol (TBP) is a typical environmental endocrine. In this paper, the OH-initiated degradation mechanism of TBP in the atmosphere is studied at the MPWB1K/6-31+G(d,p)//MPWB1K/6-311+G(3df,2p) level of computational theory. A profile of the potential energy surface is constructed and reaction pathways are analysed. The addition reactions of TBP with OH radicals are more important than abstraction reactions in the atmosphere. In subsequent reactions, O2 and NO may play an important role in the degradation process of TBP. The rate constants are calculated using the transition state theory and a canonical variational transition with small-curvature tunnelling correction. The Arrhenius equations of rate constants in the temperature range of 200–500K are fitted. The rate constant of the degradation of the TBP at 298.15K is 3.56×10–14cm3 molecule–1s–1 and the atmospheric lifetime is 10.8 months according to the pseudo-first-order kinetics.

The Effect of Different Ions on Photodegradation Rhodamine B in TiO2 Suspension Liquid

2013 ◽  
Vol 807-809 ◽  
pp. 2739-2742
Author(s):  
Peng Wei Huo ◽  
Mao Bin Wei ◽  
Xin Lin Liu ◽  
Dan Dan Wang ◽  
Zi Yang Lu ◽  
...  
Keyword(s):  
Waste Water ◽  
Photocatalytic Degradation ◽  
Rhodamine B ◽  
Degradation Rate ◽  
Ph Value ◽  
Degradation Process ◽  
Photocatalytic Process ◽  
Negative Effect ◽  
Anions And Cations

The photocatalytic degradation process of waste water was usually influenced by many factors, such as different ions, addition reagent and pH value. In order to investigate the effect of ions strength in the photocatalytic process, the anions and cations were systematically investigated with P25 TiO2 photocatalyst with Rhodamine B (RB) as waste water in this work. The results showed that the cations of low valence showed minimum negative effect on degradation rate and the most anions showed enhance the degradation rate of RB. The ions strength showed random in the photocatalytic process.

Photocatalytic degradation kinetics of humic acid in aqueous TiO2 dispersions: the influence of hydrogen peroxide and bicarbonate ion

1996 ◽  
Vol 34 (9) ◽  
pp. 73-80 ◽  
Author(s):  
Miray Bekbölet ◽  
Isil Balcioglu
Keyword(s):  
Hydrogen Peroxide ◽  
Humic Acid ◽  
Photocatalytic Degradation ◽  
Rate Constants ◽  
Degradation Rate ◽  
Ph Value ◽  
Degradation Kinetics ◽  
Color Removal ◽  
Degradation Data ◽  
Kinetics Of

The degradation of humic acid in water by means of photocatalytic method has been studied. The influence of hydrogen peroxide and bicarbonate has also been investigated. The kinetics of the photocatalytic degradation of humic acid in various concentrations (50-500 mg/L) has been followed by the determination of TOC, COD and UV-vis spectra of the reaction solution. While the pseudo first order rate constants of 50 mg/L humic acid were found 0.016, 0.03 and 0.036 for TOC, Color400 and UV254, the degradation rate constants for these parameters were found 0.029, 0.069 and 0.057 in the presence of 1×10−2M H2O2. The Langmuir-Hinshelwood kinetic has also been sucessfully applied to the photocatalytic degradation data. It was found that bicarbonate ions slowed down the degradation rate by scavenging the hydroxyl radicals. Low pH value has been found to be favorable for color removal in the absence of hydrogen peroxide whereas natural pH gave the best results for color removal in the presence of hydrogen peroxide.

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