Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using disinfecting or sterilizing substance
Reexamination Certificate
2000-12-18
2002-06-11
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using disinfecting or sterilizing substance
C422S024000, C422S028000, C422S177000, C422S180000, C422S186060, C210S760000, C210S763000
Reexamination Certificate
active
06403031
ABSTRACT:
The present invention relates to the advanced oxidation of organic pollutants of water. The invention relates more particularly to a catalytic ozonization process leading to a substantial mineralization of the organic matter present in an aqueous phase.
Organic matter is defined as the combination of oxidizable compounds which are conventionally quantified overall by the Chemical Oxygen Demand (COD) and the Biological Oxygen Demand (BOD); another parameter which is increasingly being used is the Total Organic Carbon (TOC).
On account of the simplicity of their use and their relatively low cost, biological processes are the purification techniques most commonly used for treating organic pollution. However, the activity of the microorganisms involved is limited to the removal of biodegradable organic compounds and may be inhibited in the presence of toxic substances. The treatment of non-biodegradable organic pollutants requires a chemical oxidation step.
The oldest process developed, which is known as wet-route oxidation, uses atmospheric oxygen to convert organic pollutants into carbon dioxide and water. The reaction requires operating conditions of high temperature and pressure which are located respectively in the ranges from 20° C. to 350° C. and 2×10
6
Pa to 2×10
7
Pa. In practice, the working pressure is greater than 8×10
6
Pa and the temperature is about 250° C. Metal catalysts have been developed to reduce the infrastructure and exploitation costs associated with the operating conditions. These catalysts may be homogeneous, introduced into the aqueous phase in the form of salts of the transition metals Cu
2+
, Fe
2+
, Zn
2+
, Co
2+
, etc., but in this case they impose the need for a subsequent separation treatment. Consequently, heterogeneous catalysts are nowadays developed, as disclosed in WO 96/13463 and U.S. Pat. No. 5,145,587. These solid catalysts are vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, tungsten, ruthenium, rhodium, iridium, palladium, platinum, silver, gold or bismuth metal compounds, optionally as a mixture and deposited on a mineral support such as alumina, zeolites, silica, active charcoal, titanium dioxide, zirconia, ceria, etc. Wet-route oxidation achieves a consequent reduction of the COD of waste waters charged with organic matter, such as effluents from the distilling, papermaking, petrochemical, etc. industries. However, above and beyond the difficulty of carrying it out due to the corrosive reaction medium and the formation of mineral deposits, the application of wet-route oxidation remains limited because it produces oxygenated organic compounds of low molecular weight which are very slow to mineralize.
Among the chemical oxidants used in water treatment, ozone is the most powerful reagent ((E°(O
3
)=2.08 V, E°(H
2
O
2
)=1.78 V, E°(ClOH)=1.49 V, E°(Cl
2
)=1.36 V, E°(ClO
2
)=1.27 V, E°(O
2
)=1.23 V). Given its reactivity towards organic compounds, the field of application of ozone covers the treatment of drinking waters, industrial waters and urban waste waters. Ozone is nowadays tending to replace chlorine in its role of disinfecting drinking waters on account of the absence of degradation products that are harmful to the organoleptic qualities, such as the color, odor and taste of the treated water. Ozone has been used for many years as a bactericide and virucide for drinking waters and more generally for oxidizing organic matter and micropollutants. Ozone is also the chemical oxidant of choice in the specific treatments of deferrization and demanganization. Ozonization can be applied as an additional treatment for a water which has a very high organic content, to help clarify it. Ozone converts organic pollutants into more polar compounds of lower molar masses and consequently improves their biodegradability and subsequent adsorption onto active charcoal (see for example GB 1 417 573 and FR-A-2 738 235. On account of its dipolar structure, ozone reacts readily with compounds containing unsaturation or sites of high electron density. In general, the rate of ozonization of different organic substrates follows the order of decreasing reactivity: thiol, amine, alkyne, alcohol, aldehyde, alkane, ketone, carboxylic acid and becomes very severely limiting from the alkanes onward. However, the oxidation of organic compounds generates in all cases products containing an oxygenated function which, like organochlorine compounds, are found to be inert with respect to ozone, as a result of which the overall reductions in total organic carbon remain low.
From a chemical point of view, the only means for obtaining advanced oxidation yields is to activate the oxidizing systems so as to form in the reaction medium species that are more reactive and less selective. The advanced chemical oxidation processes, known as AOPs, are based on the generation in the reaction medium of the hydroxyl radical, the redox potential of which is much higher than that of ozone (E°(HO°)=2.80 V). They involve a supply of chemical or photochemical energy to activate the ozone and induce the formation of hydroxyl radicals capable of oxidizing most organic pollutants to the point of complete mineralization.
The photochemical activation of ozone is achieved by UV irradiation and theoretically produces one mole of hydroxyl radical per 1.5 mol of ozone and 0.5 mol of photons consumed. Its efficacy is greatly limited by the presence of chromophoric substances and by the turbidity of the water to be treated, which impair the penetration of radiation. Furthermore, beside the cost engendered by the use of high-intensity irradiation, the complexity of the reactors adapted for the implementation constitutes the main stumbling block in the development of this technique (see for example U.S. Pat. Nos. 5,637,231, 5,178,755, EP-A-60941 and U.S. Pat. No. 3,924,139).
The chemical activation of ozone with hydrogen peroxide theoretically gives higher-quality performance than photochemical activation since one mole of hydroxyl radical results from the interaction of one mole of ozone and 0.5 mol of hydrogen peroxide. However, whereas the O
3
/H
2
O
2
combined system is shown to be particularly suitable for eliminating many organic micropollutants for the rendering of water fit for drinking, the gain in oxidation yield observed for industrial waste waters relative to ozonization depends greatly on the nature of the substrates to be oxidized (see for example FR-A-2 640 957, FR-A-2 563 208, FR-A-2 699 914, U.S. Pat. Nos. 4,792,407 and 4,849,114). Thus, the addition of hydrogen peroxide may prove to be entirely superfluous in the case where ozonization of the organic matter leads to the formation of hydrogen peroxide in situ. Moreover, the additional exploitation cost associated with the addition of hydrogen peroxide may be up to 100% compared with ozonization, excluding activation.
In any event, one of the major limitations of advanced oxidation processes such as ozonization with photochemical irradiation or in the presence of hydrogen peroxide lies in the mode of action itself of the oxidizing system. Specifically, free-radical-scavenging mineral or organic compounds can come into competition with the organic matter to be oxidized. This results in an inhibition of the radical-mediated oxidation process by diverting the flow of hydroxyl radicals and, consequently, a treatment efficacy which at best is equal to that of the ozonization excluding activation and a small reduction of total organic carbon. Now, ozone-decomposition inhibitors are compounds that are frequently encountered in variable concentration in waters to be treated: acetate, tert-butanol, saturated aliphatic compounds, carbonates, bicarbonates, phosphates, etc.
Another ozone activation route consists in promoting the oxidation by adsorbing the organic molecules. GB-A-2 269 167 discloses a process for ozonizing waste waters based on a specific placing in contact of the water with a mixture of ozone and oxyg
Baig Sylvie
Dartiguenave Michele
Escude Sandrine
Legay Cecile
Lucchese Yolande
Connolly Bove & Lodge & Hutz LLP
Degremont
Soubra Imad
Warden, Sr. Robert J.
LandOfFree
Method for mineralization of organic pollutants in water by... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for mineralization of organic pollutants in water by..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for mineralization of organic pollutants in water by... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2977016