Methods of remediating liquid compositions containing sulfur and other contaminants

Abstract

A treatment process for remediating H.sub.2S and other contaminants in liquids includes: partially filling a closed vessel with a contaminated liquid containing ≥5 ppm H.sub.2S with a head space above the liquid within the vessel where gasses released from the liquid from the liquid collect; separately providing a treatment composition in the head space so that the gasses from the liquid may contact the treatment composition; and permitting the contact between the vapors from the liquid and the treatment composition to continue until a collective concentration of H.sub.2S in the liquid and in the head space is <5 ppm. The treatment composition includes an aqueous solution containing at least one hydroxide compound, a collective concentration of the at least one hydroxide compound in the aqueous solution is in a range of 35-55 weight %, and the aqueous solution constitutes at least 80 weight % of the treatment composition.

Claims

1. A treatment process for remediating H.sub.2S and other contaminants in contaminated liquids comprising steps of: disposing an amount of a contaminated liquid containing ≥5 ppm H.sub.2S in a vessel of a closed remediation system such that the liquid partially fills the vessel and a head space is defined within the vessel above the liquid where vapors from the liquid collect; providing a treatment composition in the head space such that the vapors from the liquid may contact the treatment composition; and permitting the contact between the vapors from the liquid and the treatment composition to continue until a collective concentration of H.sub.2S in the liquid and in the head space is <5 ppm, wherein the treatment composition includes an aqueous hydroxide solution containing at least one hydroxide compound, a collective concentration of the at least one hydroxide compound in the aqueous hydroxide solution is in a range of 35-55 weight %, and the aqueous hydroxide solution constitutes at least 80 weight % of the treatment composition.

2. The treatment process according to claim 1, wherein the the treatment process is carried out at a temperature of 10 to 75° C. and a pressure of 0.5 to 5 atmospheres.

3. The treatment process according to claim 1, wherein the aqueous hydroxide solution constitutes at least 90 weight % of the treatment composition.

4. The treatment process according to claim 3, wherein the treatment composition further includes at least one of fulvic acid and humic acid, and collectively the at least one of fulvic acid and humic acid constitutes 0.01-4 wt % of the treatment composition.

5. The treatment process according to claim 3, wherein the aqueous solution includes equal amounts of sodium hydroxide (NaOH) and potassium hydroxide (KOH), and an amount of the treatment composition provided in the head space is ≤1% volume of the amount of the contaminated liquid.

6. The treatment process according to claim 1, wherein the treatment, composition further includes at least one of a chelating agent, a surfactant and a buffering agent.

7. The treatment process according to claim 6, wherein the chelating agent is ethylenediaminetetraaceticacid (EDTA), and the treatment composition includes 0.5 to 50.0 ml EDTA/liter of treatment, composition.

8. The treatment process according to claim 1, wherein the step of providing the treatment composition in the head space involves placing the treatment solution in an open container and disposing the open container with the treatment composition in the vessel such that the vapors from the liquid as collected in the head space may contact the treatment composition.

9. The treatment process according to claim 1, wherein the system also includes a supply of the treatment composition separate from the vessel, and the step of providing the treatment composition in the head space involves forming a gaseous mixture containing fine droplets of the treatment composition from the supply of the treatment composition and flowing the gaseous mixture into the head space of the closable vessel.

10. The treatment process according to claim 9, wherein the system further includes a device which generates the mixture containing fine droplets of the treatment composition and which is in fluid communication with the head space of the vessel,and the method includes further steps of withdrawing at least some of the gaseous mixture containing fine droplets of the treatment composition from the head space, and re-circulating the withdrawn gaseou mixture back into the headspace.

11. The treatment process according to claim 1, wherein the contaminated liquid further includes CO.sub.2 as another contaminant.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic diagram of a reaction chamber which may be used in an exemplary embodiment of the present invention.

(2) FIG. 2 is a schematic diagram of a reaction chamber which may be used in another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF PRESENT EXEMPLARY EMBODIMENTS

(3) Exemplary embodiments of the present invention will be described below. Primary aspects of the present invention involve use of novel treatment compositions in treatment processes for contaminated liquids wherein the treatment compositions are not fully combined/mixed with the contaminated liquids.

(4) Processes for Treating Contaminated Liquids Involving Treatment Compositions not Fully Combined with the Liquids

(5) Again, the present inventors have carefully investigated caustic treatment of petroleum based liquids including crude oil, as well as other contaminated liquids, for removing H.sub.2S and other contaminants therefrom, and have discovered that treatment compositions such as those they have previously proposed in PCT/US2018/050913 and PCT/US2018/064015, as well as modifications thereof, may be very effectively and efficiently used to treat contaminated liquids containing H.sub.2S and other sulfur based contaminants without fully mixing or combining the treatment composition with the contaminated liquids. Instead the treatment compositions are separately provided in a closed space/reaction chamber with the contaminated liquids such that vapors of the H.sub.2S and other contaminants which are naturally released from the contaminated liquids at low pressures such as atmospheric pressure may contact the treatment compositions and be remediated by reacting with same.

(6) This discovery made by the inventors relates to the fact that at atmospheric pressure and temperature H.sub.2S will primarily exist in vapor phase, rather than in a petroleum based liquid or water based liquid, and that for many substances such as H.sub.2S, the reactivity of the substances is much greater in the vapor phase than in the liquid phase. Particularly, the inventors have discovered that by providing the treatment compositions separately from the contaminated liquids within a closed chamber in such a manner that H.sub.2S vapor coming out of the contaminated liquids may contact the treatment solutions, this can be sufficient for fully remediating the H.sub.2S and other sulfur based contaminants, while using much less of the treatment compositions than if the treatment compositions are fully combined with the contaminated liquids. For example, according to the inventors' previous proposals a typical dosage of treatment composition used would be within a range of 0.25-6.0 ml/liter of the liquid being treated, preferably within a range of 1.0-5.0 ml/liter of the liquid being treated, whereas according to the exemplary embodiment of the present invention may be reduced to ½, ⅕ th or even 1/10th of the amounts used in the previous proposal where the treatment composition is fully added to the contaminated liquid. The reactions between the hydroxide compound(s) and H.sub.2S and other targeted contaminants are essentially the same as discussed in PCT/US2018/050913 and PCT/US2018/064015. Under such conditions the vapors of H.sub.2S and other contaminants as released from the crude oil or other liquid will readily react with the hydroxide compound(s) of the treatment composition and be remediated down to safe, acceptable levels such as 5 ppm or less within 1-3 hours. Hence, the treatment process according to the exemplary embodiment of the present invention may achieve a correspondingly lower cost and greater efficiency that the inventors' previously proposed treatment processes.

(7) Generally, the primary component of the previously proposed treatment solutions as disclosed in PCT/US2018/050913 and PCT/US2018/064015 is an aqueous hydroxide solution containing at least one hydroxide compound, wherein the aqueous hydroxide solution constitutes at least 80 weight % and preferably at least 90 weight % of the treatment composition, and wherein the collective concentration of the at least one hydroxide compound in the aqueous hydroxide solution is in a range of 35-55 wt %. A pH of the treatment composition may be ≥9.0, and preferably ≥13.0. These previously proposed treatment compositions may also be used in the exemplary embodiment of the treatment process according to the present invention, although the inventors have determined that specific formulations of the previously proposed compositions may work especially well in the present treatment process. The treatment composition according to this embodiment of the present invention may include a single hydroxide compound or a combination of multiple different hydroxide compounds, including sodium hydroxide (NaOH), potassium hydroxide (KOH), magnesium hydroxide (Mg(OH).sub.2), lithium hydroxide (LiOH) and manganese hydroxide (Mn(OH).sub.2, Mn(OH).sub.4) in various ratios, but with a collective total hydroxide concentration of 35-55 wt %, and preferably 45-55 wt %. Incidentally, however, the inventors have also found that if the treatment composition used in the treatment process according to the present invention contains substantially equal amounts of NaOH and KOH as the hydroxide compounds of the treatment composition, the treatment composition is unexpectedly much more reactive, e.g., three times more reactive, than a similar treatment composition containing the same total concentration of these hydroxide compounds, but in a ratio of 80% NaOH/20% KOH.

(8) The exemplary embodiment of the present treatment composition may include other components such as other components used in the previously proposed treatment solutions. For example, the treatment composition may include one or more organic acids such as fulvic acid and humic acid which help to prevent the remediated H.sub.2S and other contaminants from precipitating out of the treated liquids, MEA which provides an anti-scaling effect, an anti-bacterial agent such as a silicate such as potassium silicate or barium, other possible components of the treatments solutions as disclosed in PCT/US2018/050913 and PCT/US2018/064015, etc. The exemplary embodiment of the present treatment composition may include other components, as well, including EDTA which helps to improve molar reactivity of the hydroxide compound(s), a surfactant, a buffering agent, etc. However, it is not clear if these other components provide the same effects and to the safe extent in the treatment according to the exemplary embodiment of the present invention as they provide in the treatment processes of PCT/US2018/050913 and PCT/US2018/064015, again, because the present treatment composition is not fully mixed into the contaminated liquids in the treatment process of the present invention, unlike how the treatment solutions are used in the treatment processes disclosed in PCT/US2018/050913 and PCT/US2018/064015.

(9) A concentration of the hydroxide compound(s) in the aqueous hydroxide solution of the treatment composition below 35 wt % may be used, but the time required to fully remediate the contaminants would likely be increased. On the other hand, it may be desirable to increase the amount of the treatment composition to ≥1% volume if the contaminated liquid includes any significant amount of CO.sub.2, e.g., ≥250 ppm, because the CO.sub.2 will also be released from the contaminated liquid and hydroxides react with the CO.sub.2 as well as with H.sub.2S and other sulfur based contaminants. Generally, once a contaminated liquid is fully remediated by the process according to the first aspect of the present invention, the treatment composition used for the remediation may not be fully spent, and may be used again for treating additional quantities of contaminated liquids, either as is or with a supplemental amount of the treatment composition added thereto. Thus, the treatment process according to the first aspect of the present invention is more cost effective that the present inventors' previously proposed treatment process in which a similar amount of treatment composition is directly, fully added to the contaminated liquid. Also, it may be appropriate to include a greater amount of the treatment composition in the head space of the reaction chamber than 1 volume % as this would not cause any detrimental reactions, whereas the same treatment composition may be subsequently used/reused for treating additional amount(s) of contaminated liquids. Hence, using the greater amount of the treatment composition above 1 volume % should not increase the cost of the treatment process because the same composition can be used repeatedly and the cost will be spread out over the number of times the treatment composition is used.

(10) The treatment composition according to the first aspect of the invention may include other components of the treatments solutions as disclosed in PCT/US2018/050913 and PCT/US2018/064015, including an organic acid such as fulvic acid and humic acid which help to prevent the remediated H.sub.2S and other contaminants from precipitating out of the treated liquids and gasses, MEA which provides an anti-scaling effect, a silicate or barium which provide an anti-bacterial effect, etc. These additional components may be added in similar quantities or proportions as discussed in PCT/US2018/050913 and PCT/US2018/064015 and may provide the same beneficial effects in the treatment process according the first aspect of the present invention as they do when the treatment composition is fully added to/combined with the contaminated liquids. For example, a treatment composition according to an embodiment of the present invention may include organic acid(s) such as fulvic acid and humic acid in a collective amount of 0.01-4.0 wt %, and preferably 0.05-2.0 wt %, of the treatment composition. Similarly, MEA may be added to the treatment composition in an amount of 0.01-4.0 wt %, preferably 0.05-2.0 wt %.

(11) The treatment composition according to the first aspect of the invention may also include other components besides those of the treatments solutions as disclosed in PCT/US2018/050913 and PCT/US2018/064015. For example, the treatment composition may include a chelating agent such as ethylenediaminetetraacetic acid (EDTA), a surfactant, a buffering agent, etc. EDTA may be added at 0.5-50 ml/liter of composition, while a surfactant and a buffering agent may each be added at 0.01 to 1 ml/liter of treatment composition.

(12) EDTA is particularly effective for controlling the pH of the treatment composition to remain above 8 in that EDTA is a alkali base with a PH of 14 and slows the decrease of the pH of the treatment composition as it is used over a period of time. This is advantageous because the high pH favors reaction between the hydroxide compound(s) and the H.sub.2S in the natural gas as discussed above, such that a given amount of the treatment composition can be effectively used for remediating more of the H.sub.2S in comparison to an equal amount of treatment composition which does not include EDTA. In other words, the EDTA or other chelating agent effectively extends the useful life of the treatment composition. Incidentally, EDTA has been used in previous times as a primary reactant in a method of mitigating H.sub.2S. However, the required molar reaction time is long and the molar reaction ratio is 1 mole EDTA to 1 mole H.sub.2S, such that high concentrations of H.sub.2S would require large doses of chemical for a long treatment period, which is not well suited to treatment of contaminated natural gas containing significant amounts of H.sub.2S. Addition of a surfactant such as sodium lauryl sulfate and buffering agent such as potassium carbonate may enhance the effectiveness of the other components.

(13) According to an exemplary embodiment of the present invention there is provided a treatment process for remediating H.sub.2S and other contaminants in contaminated liquids which includes steps of: disposing an amount of a contaminated liquid containing ≥5 ppm H.sub.2S in a closed or closable vessel such that the liquid partially fills the vessel and a head space is defined within the vessel above the liquid where any gasses discharged from the liquid may collect; providing a treatment composition in the head space such that the gasses from the liquid may contact the treatment composition; and permitting the contact between the gasses from the liquid and the treatment composition to continue until a collective concentration of H.sub.2S in the liquid and in the head space is <5 ppm. Again, the treatment composition used in this treatment process may have a composition as those disclosed in PCT/US2018/050913 and PCT/US2018/064015, or a variation of the previously discloses compositions, as discussed above.

(14) The step of providing the treatment composition in the head space of the reaction chamber may be accomplished in various manners according to the exemplary embodiment of the present invention. With reference to FIG. 1, there is shown a schematic diagram of a vessel 1 having a reaction chamber therein, which may be used in an exemplary embodiment of the present invention. The vessel 1 is closed or closable such that no gas or liquid may unintentionally escape from the reaction chamber during a treatment process, noting that gaseous H.sub.2S is very toxic to humans, and a contaminated liquid 2 such as crude oil may be loaded into the vessel so that it occupies much of the space in the vessel, while a head space 4 is defined at the upper portion of the closed vessel above the liquid such that the gaseous H.sub.2S and other gaseous contaminants released from the liquid may collect in the head space. An amount of an aqueous based treatment composition 6 according to the exemplary embodiment of the present invention may be placed in an open container 8 which is disposed in the closed vessel such that the vapors of H.sub.2S and other contaminants which collect in the head space 4 may contact the treatment composition. The amount of the treatment composition used may be ≤1% in comparison to the volume of the contaminated liquid being treated, even as low as, e.g. 0.01-0.1. % volume.

(15) As another example, a closable system 10 such as shown in FIG. 2 may be used. The system 10 includes a closed or closable vessel 11 having a reaction chamber therein in which an amount of a contaminated liquid 12 such as crude oil may be loaded so that it occupies much of the space in the vessel, while a head space 14 is defined at an upper portion of the vessel above the liquid such that the gasses of H.sub.2S and other contaminants released from the liquid may collect in the head space. The system may further include a supply 16 of a treatment composition according to the exemplary embodiment of the present invention, a device 18 such as an ultrasonic humidifier for generating a gaseous mixture containing fine droplets of the treatment composition, a pump 20 and a controller 22 such as a microcomputer programmed to control operations of the system. For example, the controller may cause the system to generate a gaseous mixture containing fine droplets of the treatment composition and flow the gaseous mixture into the head space 14. The gaseous mixture may be circulated and re-circulated through the head space and, if necessary, additional fine droplets of the treatment composition may be added to the circulating gaseous mixture during the treatment process.

(16) An effective amount of the treatment composition to be provided in the head space according to either of the arrangements in FIGS. 1-2 may be ≤1% volume compared to the volume of contaminated liquid being treated, and even less than 0.1% volume of the amount of the contaminated liquid being treated, and may be significantly less that the amounts of the treatment solutions used in the treatment processes disclosed in PCT/US2018/050913 and PCT/US2018/064015, again, because the treatment compositions are not fully mixed into the treated liquids. However, it may be desirable to increase the amount of the treatment composition if the contaminated liquid includes a significant amount of CO.sub.2, e.g., at least 250 ppm, because hydroxides in the treatment composition react with the CO.sub.2 as well as with H.sub.2S and other contaminants. With the embodiment of FIG. 1 involving an open container of treatment composition, once a contaminated liquid is fully remediated by the treatment process according to the embodiment of the present invention, the treatment composition used for the remediation may still possess much or most of its original reactivity, and may be used again for treating additional quantities of contaminated liquids, either as is or with a supplemental amount of the treatment composition added thereto. Thus, the treatment process according to the first aspect of the present invention is more cost effective that the present inventors' previously proposed treatment process in which a similar amount of treatment composition is directly, fully added to the contaminated liquid. Also, it may be appropriate to include an amount of the treatment composition in the head space of the reaction chamber ≥1 volume % as this should shorten the time necessary to remediate the H.sub.2S and other contaminants in the treated liquid and would not cause any detrimental reactions, whereas the same treatment composition may be subsequently used/reused for treating additional amount(s) of contaminated liquids. Hence, using the greater amount of the treatment composition ≥1 volume % should not increase the cost of the treatment process because the same composition can be used repeatedly and the cost will be spread out over the number of times the treatment composition is used.

(17) The treatment process may be conveniently carried out at a temperature and pressure which substantially correspond to standard temperature and pressure, e.g., a temperature of 20-25° C. and a pressure of one atmosphere, but other temperatures and pressures are also suitable. At higher temperatures, e.g., up to 75° C. the H.sub.2S and other targeted contaminants may be released from the contaminated liquid at faster rates than at ambient temperature, but at higher pressures above one atmosphere these contaminants will be released at slower rates from the contaminated liquids. Under such conditions, and regardless of how the treatment composition is provided in the head space of the reaction chamber to react with vapors of H.sub.2S and other contaminants, the concentrated hydroxide(s) contained in the treatment composition quickly reacts with the gasses of H.sub.2S and other sulfur based contaminants released from the liquid being treated and remediates the amounts of H.sub.2S and other contaminants in the contaminated liquids down below 5 ppm in a fairly short time period such as 15 minutes to 3 hours. Again, this is due to the fact that H.sub.2S and other sulfur based contaminants will naturally be released into vapor phase rather than remaining in the contaminated liquids at atmospheric pressure, and are more reactive when in vapor phase. As the vapor phase contaminants react with the treatment composition, additional amounts of the gasses of H.sub.2S and other contaminants will be released from the liquid being treated based on principles of equilibrium and will similarly react with the hydroxide compound(s) in the treatment composition until essentially all of the H.sub.2S and other contaminants are released as gasses from the liquid and are remediated down to safe, acceptable levels such as 5 ppm or less. Hence, the H.sub.2S and other sulfur based contaminants in the treated liquids are fully and quickly remediated by the treatment process of the present invention at least as efficiently as in the treatment processes of PCT/US2018/050913 and PCT/US2018/064015. Further, the elements or other compounds which are generated from the remediated H.sub.2S and other contaminants will tend to stay dissolved in the treated liquids, rather than being released from the liquid as precipitates, scale or the like, particularly if the treatment composition includes components which tend to prevent formation of precipitates, e.g., organic acids such as fulvic acid and humic acid, MEA and EDTA. However, other effects of the treatment process treatment process according to the present invention may be somewhat different from those achieved with the treatment processes of PCT/US2018/050913 and PCT/US2018/064015 as discussed further herein.

(18) For example, the inventors have found that if the vapors from the contaminated liquid and the treatment composition are permitted to further react after the concentration of H.sub.2S and other contaminants is remediated down to concentrations of 5 ppm or less, then the elements or other compounds which are generated from the remediated H.sub.2S and other contaminants may tend to precipitate out of the treated liquids, at least temporarily, but may eventually go back into the treated liquid in remediated, non-toxic form(s), as in the Example below.

(19) Further, when the treatment process of the present invention involves exposing the treatment composition within an open container provided in the reaction chamber as in FIG. 1, based on analyses of the treatment composition as originally provided, as well as after the composition was used for treating contaminated liquids in the treatment process of the present invention, the reactive components of the treatment composition may remain near their original concentrations after the content of H.sub.2S and other contaminants has been remediated down to acceptable levels, even if the original concentrations of H.sub.2S and other contaminants in the treated solutions were relatively high, e.g., concentration of H2S in a range of 20,000-40,000 ppm. This permits such treatment composition to be used again for treating other contaminated liquids. However, each time the treatment composition is used it will lose some of its potency or reactivity, and after the treatment composition has been used a number of times for treating contaminated liquids, the concentrations of components of the treatment composition will gradually be reduced, the pH of the solution will gradually increase, and at some point the treatment composition will not be sufficiently effective for continued use.

(20) On the other hand, when the treatment composition is provided as fine droplets in a gaseous mixture which flows into and possibly circulates through the head space of the vessel as in FIG. 2, while it is not practical to reuse such fine droplets of the treatment composition for treating additional amount(s) of contaminated liquids, far less of the treatment composition is used for such treatment process in comparison to the previously proposed treatment processes of PCT/US2018/050913 and PCT/US2018/064015 in which quantities of the liquid treatment solutions are simply mixed into the contaminated liquids. For example, the amount of treatment composition used in such treatment process according to the present invention may be only 10-50% volume of the amount of the treatment solutions used in the previously proposed treatment processes.

(21) Example of Treatment Process

(22) In an experiment conducted by the inventors, a contaminated diesel fuel containing 40,000 ppm of H.sub.2S as a main contaminant was treated according to the treatment process of the present invention using a treatment composition which corresponds to a treatment solution as disclosed in PCT/US2018/064015, including primarily an aqueous hydroxide solution of NaOH and KOH at a ratio of 97:3 and a total or collective concentration of the hydroxide compounds of about 50 wt %, together with about 1 wt % of each of fulvic acid and monoethanolamine (MEA). One liter of the contaminated diesel fuel was placed in a closed reaction vessel with a head space above the liquid fuel and an open container containing 10 ml of the treatment composition was placed in the reaction vessel such that the treatment composition was exposed within the head space. After 1.5 hours there was less than 1 ppm of H.sub.2S in diesel fuel, as well as in the vapors in the head space of the reaction chamber, and there was no precipitate(s) in the treated diesel fuel. The diesel fuel was then left to further react with the treatment composition and after 4.0 hours total, including the original 1.5 hours, there was still less than 1 ppm of H.sub.2S in diesel fuel, as well as in the vapors in the head space of the reaction chamber, but a significant amount of precipitate(s) were formed in the diesel fuel. Analysis of the precipitate(s) showed that the precipitate(s) were primarily elemental sulfur (S), while analysis of the treated diesel fuel showed that not only did it contain less than 1 ppm H.sub.2S, but the total sulfur content of the diesel fuel had been reduced by approximately 50 wt %. The diesel fuel was again left to further react with the treatment composition and after 24.0 hours total, including the prior 4.0 hours, there was still less than 1 ppm of H.sub.2S in diesel fuel, as well as in the vapors in the head space of the reaction chamber, but there was no precipitate(s) in the treated diesel fuel as all of the precipitate(s) that had been present after 4.0 hours had again, been taken up—dissolved into the treated diesel fuel. The treatment composition was analyzed after the 24 hour treatment process, and the analysis shows that each of the components of the composition, hydroxide compounds, fulvic acid and MEA, remained at or near their original concentrations.

(23) The above exemplary embodiment of a treatment method using a treatment composition according to the present invention provides several significant advantages over other known treatment processes for remediating H.sub.2S and other contaminants in liquids. For example, it can quickly and efficiently remediate the H.sub.2S and other contaminants in the liquids and in the head space down to safe, acceptable levels, e.g., ≤1 ppm, within 1-3 hours, and does so while using significantly less of the treatment solution than would be required if the treatment composition was fully mixed into a contaminated liquid according to the inventors' previous proposals. For example, if the treatment composition is disposed in an open container for contact with gasses of H.sub.2S and other contaminants in the head space of the closed vessel, the components of the treatment composition will typically remain at or near their original concentrations after the content of H.sub.2S and other contaminants has been remediated down to acceptable levels, even if the original concentrations of H.sub.2S and other contaminants in the treated solutions were relatively high, e.g., concentration of H.sub.2S in a range of 20,000-100,000 ppm. This permits such treatment composition to be used again for treating additional amounts of contaminated liquids, although after the treatment composition has been used a number of times for treated contaminated liquids, the concentrations of components of the treatment composition will gradually be reduced, the pH of the solution will gradually increase, and at some point the treatment composition will not be sufficiently effective for continued use.

(24) Similarly, if the treatment method involves applying the treatment composition in a gaseous mixture containing fine droplets of the treatment composition which flows into the head space of the closed vessel, the amount of the treatment composition required for remediating the H.sub.2S and other contaminants in the liquids being treated may be far less than 1% volume of the amount of the contaminated liquid, e.g. 0.005-0.01% volume.

(25) Another advantage, is that the treatment composition containing sodium hydroxide (NaOH) and potassium hydroxide (KOH) in approximately equal weight percentages is unexpectedly much more reactive than a similar treatment solution containing the same total concentration of these hydroxides in a range of 35-55 wt %, but in a ratio of 80% NaOH/20% KOH.

(26) The foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications within the scope of the invention may be apparent to those having ordinary skill in the art and are encompassed by the claims appended hereto.