Catalytically Treating Water Contaminated With Halogenated Organic Compounds

Abstract

Catalytically treating groundwater (10), surface water, or above surface water, contaminated (12) with halogenated organic compounds being members of chlorotriazine, chloroacetanilide, or halogenated aliphatic, herbicide groups, and, halogen containing analogs and derivatives thereof. Method: exposing contaminated water to catalytic amount of electron transfer mediator (18) under reducing conditions, to decrease concentrations of halogenated organic compounds. System: at least one electron transfer mediator (18) contained in at least one (in-situ or / and ex-situ) unit (20), for exposing to contaminated water under reducing conditions. Exemplary electron transfer mediators are porphyrinogenic organometallic complexes, being metalloporphyrins, metallocorrins, or metallochlorins. Exemplary metalloporphyrins are a [TMPyP], [TP(OH)P], [TPP], or [TBSP], free base porphyrin complexed to a transition metal (cobalt, nickel, iron, zinc, or copper). Implemented according to homogeneous or / and heterogeneous catalysis, via batch or flow mode. Reducing conditions naturally exist, or / and are anthropogenically produced, in the contaminated water. Applicable to in-situ groundwater permeable reactive barriers (PRBs) (22).

Description

FIELD AND BACKGROUND OF THE INVENTION[0001]The present invention relates to the field of environmental science and technology focusing on treating or remediating water contaminated or polluted with halogenated organic compounds, where the contaminated or polluted water is a form of groundwater, surface water, above surface water, or a combination thereof. More particularly, the present invention relates to a method of catalytically treating water contaminated with halogenated organic compounds, and a system thereof, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. These herbicide type halogenated organic compounds, at room temperature and atmospheric pressure, are non-volatile particulate substances (nearly all) or liquids (some) which, at typical contaminant...

AI Technical Summary

Benefits of technology

[0074]The method of catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, of the present invention, includes the main procedure of exposing the contaminated water to a catalytically effective amount of at least one electron transfer mediator under reducing conditions, to thereby decrease the concentration of at least one of the halogenated organic compounds in the contaminated water.

[0076]The method and system of the present invention are based on using a chemical technique for catalytically treating the contaminated water, by exploiting catalytic chemical reaction types of phenomena, mechanisms, and processes, involving the use of at least one electron transfer mediator functioning as an active redox catalyst under reducing (typically, anaerobic or anoxic) conditions, for in-situ or / and ex-situ, homogeneously or / and heterogeneously, catalytically degrading, transforming, or converting, in particular, via reductive dehalogenation (typically, dechlorination) of, the halogenated organic compounds in the contaminated water to non-hazardous or / and less hazardous (poisonous or toxic) chemical species. Implementation of the present invention results in decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water.

[0102]Thus, according to the present invention, there is provided a method of catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogenated analogs thereof, halogenated derivatives thereof, and combinations thereof, the method comprising exposing the contaminated water to a catalytically effective amount of at least one electron transfer mediator under reducing conditions, to thereby decrease concentration of at least one of the halogenated organic compounds in the contaminated water.

Problems solved by technology

It is now recognized that these properties, which are essential to industry, have devastating effects on the environment, translating to undesirable short and long term health problems.

Discharge of these compounds into surface and sub-surface environments has led to extensive surface water and groundwater contamination or pollution.

Largely based on the fact that groundwater accounts for about 95% of the earth's usable fresh water resources, groundwater contamination or pollution is a critical issue, and intensive efforts are continuously being invested in the development of improved and new technologies for treating or remediating water contaminated or polluted with halogenated organic compounds, where the contaminated or polluted water is a form of groundwater, surface water, above surface water, or a combination thereof.

2)), and their degradation products (especially higher water mobile halogen (in particular, chlorine) containing derivatives), are pervasive, persistent, proven or potentially hazardous (poisonous or toxic), undesirable contaminants or pollutants in various forms of water, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof.

Well water surveys [e.g., 8] have shown that many aquifers are contaminated with high levels of CONHs.

Additional studies on the ecological impact of CONHs have implicated individual CONHs, as well as mixtures of CONHs, and their degradation products, as endocrine disruptors in fish, for example, leading to adversely affecting reproduction of game fish such as bass (Micropterus salmoides).

Despite such restrictions, regulations, and bans, atrazine (as just one of the numerous CONHs included in the broader and more general category of halogenated organic herbicides), remains a major hazardous water contaminant.

In spite of proven and potential environmental and health hazards, many halogenated organic herbicides, among the wide variety of different types of persistent water contaminants, currently remain in widespread international use, thereby perpetuating a continuously on-going problem.

Main problems associated with treating or remediating groundwater are that such contaminant zones or regions (plumes) tend to be very difficult to locate, detect, characterize, and treat; heterogeneities are often present in groundwater environments; and long periods of continuous groundwater flow are often required for contaminants, and possible degradation products, to be sufficiently removed from contaminated groundwater.

A significant limitation of the activated carbon filtration technique is that the halogenated organic compound contaminants are essentially only transferred from the contaminated water to the carbon filter, without being converted or detoxified to non-hazardous or / and less hazardous environmentally acceptable compounds.

Additionally, implementation of this technique requires resources (manpower and equipment) for removing, and disposing of, or, regenerating, the contaminant containing de-activated carbon filter.

However, a significant limitation of using microbiological techniques for treating contaminated water is that, typically, they are strongly influenced, and may be inactivated, by changes in environmental conditions, such as pH, temperature, and nutrient supply, which take place during the water treatment, especially during long term water treatment.

Pure culture bacteria used atrazine as a sole source of carbon and / or nitrogen, but degradation was partial and mineralization happened only in a few cases.

Handling of pure culture bacteria in actual field conditions is a cumbersome job and atrazine mineralization in situ condition was almost non-existent.

Another significant limitation of using microbiological systems for treating water contaminated with halogenated organic compounds is that high contaminant concentrations can be poisonous or toxic to the contaminant degrading bacteria.

However, such studies provide no explicit or implicit teaching about catalytically treating or remediating (phytoremediating) water contaminated or polluted with halogenated organic herbicides, in general, for example, halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular.

However, no such prior art provides explicit or implicit teaching about (homogeneously or heterogeneously) catalytically treating or remediating water contaminated or polluted with halogenated organic herbicides, in general, for example, halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular.

However, no such prior art provides explicit or implicit teaching about (homogeneously or heterogeneously) catalytically treating or remediating water contaminated or polluted with halogenated organic herbicides, in general, for example, halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular.

More generally, currently known non-catalytic reductive dehalogenation (typically, dechlorination) reaction systems, or electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation (typically, dechlorination) reaction systems, are ordinarily not technologically or / and economically feasible or viable for treating or remediating water contaminated or polluted with halogenated organic herbicides.

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