US-12617701-B2 - Use of a chlorine dioxide precursor for controlling ion metabolism of bacteria in cooling water systems

US12617701B2US 12617701 B2US12617701 B2US 12617701B2US-12617701-B2

Abstract

A method of reducing activity of sulfur and/or nitrogen metabolizing bacteria is provided. The method includes adding a composition of an alkali metal salt of chlorite and/or an alkali metal salt of chlorate and hydrogen peroxide to process water of a cooling tower and increasing a concentration of the composition from about 0 ppm to about 300 ppm in about 1 to about 100 minutes.

Inventors

Amit Gupta
David Hardie Rodman
Fritz Earwin Perez MONTEROZO
Dinesh Balkisan Mantri
Tomy SURYATAMA
Fajar Muhammad RAHMAN
Achmad SYAH
Nugraha Yohannes ARIFPIN

Assignees

ECOLAB USA INC.

Dates

Publication Date: 20260505
Application Date: 20221128

Claims (12)

1 . A method of reducing activity of a bacteria, comprising: adding a composition comprising an alkali metal salt of a chlorite and/or an alkali metal salt of a chlorate and hydrogen peroxide to a process water of a cooling system, the process water comprising the bacteria; increasing a concentration of the composition in the process water from about 0 ppm up to about 300 ppm in about 1 minute to about 100 minutes; measuring a first sulfate concentration in the process water at a position at or near a bottom of a cooling tower basin; measuring a second sulfate concentration in the process water at a position at or near a surface of the process water; calculating a sulfate concentration difference between the first sulfate concentration and the second sulfate concentration; and adding the composition to the process water when the sulfate concentration difference reaches a predetermined value.
2 . The method of claim 1 , wherein the bacteria is selected from the group consisting of sulfur metabolizing bacteria, nitrogen metabolizing bacteria, and any combination thereof.
3 . The method of claim 1 , wherein the concentration of the composition in the process water increases from about 0 ppm up to about 300 ppm in about 1 minute to about 15 minutes.
4 . The method of claim 1 , wherein the concentration of the composition in the process water is increased from about 0 ppm up to about 150 ppm.
5 . The method of claim 1 , further comprising decreasing a conductivity of the process water after adding the composition.
6 . The method of claim 1 , further comprising decreasing a sulfate, a nitrite, and/or a nitrate concentration in the process water after adding the composition.
7 . The method of claim 1 , further comprising increasing a pH of the process water after adding the composition.
8 . The method of claim 1 , wherein the composition is added to the process water when the sulfate concentration difference is from about 3 to about 20 ppm.
9 . The method of claim 1 , wherein the composition comprises about 5 wt % to about 60 wt % of the alkali metal salt of chlorite and/or chlorate and about 0 wt % to about 30 wt % of the hydrogen peroxide.
10 . The method of claim 1 , wherein the cooling system includes a direct contact condenser.
11 . A method of reducing activity of a bacteria, comprising: adding a composition comprising an alkali metal salt of a chlorite and/or an alkali metal salt of a chlorate and hydrogen peroxide to a process water of a cooling system, the process water comprising the bacteria; increasing a concentration of the composition in the process water from about 0 ppm up to about 300 ppm in about 1 minute to about 100 minutes; measuring a first nitrite and/or nitrate concentration in the process water at a position at or near a bottom of a cooling tower basin; measuring a second nitrite and/or nitrate concentration in the process water at a position at or near a surface of the process water; calculating a nitrite and/or nitrate concentration difference between the first nitrite and/or nitrate concentration and the second nitrite and/or nitrate concentration; and adding the composition to the process water when the nitrite and/or nitrate concentration difference reaches a predetermined value.
12 . The method of claim 11 , wherein the composition is added to the process water when the nitrite and/or nitrate concentration difference is from about 3 ppm to about 20 ppm.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63/418,147, filed Oct. 21, 2022, and U.S. Provisional Application No. 63/285,234, filed Dec. 2, 2021, the entire disclosure of each of which is incorporated herein by reference. BACKGROUND 1. Field of the Invention The present disclosure generally relates to controlling ion metabolism of bacteria in cooling water systems. 2. Description of the Related Art Bacteria in process waters are capable of utilizing different inorganic and organic matter as sources of nutrition or energy. For example, sulfate reducing bacteria utilize sulfate and reduce it to form sulfite, which is further metabolized by different microorganisms to form sulfide (H2S) and subsequently can result in the formation of sulfurous acid and sulfuric acid. The formation of these species can result in corrosion. Also, the formed sulfite ions consume any oxidizing biocide and are oxidized to form sulfate ions, thus recreating the food source for the microorganism that formed the sulfite or reducing agent. Similarly, different nitrogen metabolizing bacteria can result in the formation of a nitrite species that acts as a reductant to consume the oxidizing biocide. In both of these examples, the presence of microorganisms results in the formation of a reducing species that consumes the biocide and reduces its efficacy. As a result, adequate amounts of the biocide are not available to control microbial populations, which are able to proliferate and present more demand in the form of organic matter and increased metabolic byproducts. These problems can occur in, for example, freshwater and/or seawater open recirculating systems as well as geothermal cooling water systems. Geothermal energy is energy in the form of heat within the earth's interior, which is tapped by geothermal wells. Geothermal energy moves towards the earth's surface by thermal conduction through solid rock. Thermal energy can also be transmitted towards the earth's surface by movement of molten rock or by circulation of fluid (H2O as steam or water) through interconnected fractures and pores, which may provide heat reservoirs closer to the surface, and thus a site more accessible to drilling for wells to tap geothermal energy. Natural geothermal reservoirs, on which many commercial geothermal wells are located, comprise volumes of rock at high temperatures (up to about 350° C. or 622° F.) and often also of high porosity and high permeability to fluids. Wells are drilled into such a reservoir and the thermal energy in the rock is transferred by conduction to a fluid (H2O as water or steam), which subsequently flows to the well and then up to the earth's surface. In areas where the rock has a low porosity and permeability, it must be artificially fractured by means of explosives or hydrofracturing to provide a network of such fractures, commonly known as Enhanced Geothermal Systems (EGS). Geothermal cooling systems that include contact condensers or use geothermal condensate as make-up water have a unique challenge for the proliferation of sulfur metabolizing bacteria and nitrogen metabolizing bacteria. Similar challenges may also be presented in other industrial water systems, such as cooling water systems. Reduced sulfur and nitrogen ionic species in the system are being assimilated by the bacteria as sources of energy and produce unwanted by-products, such as sulfuric acid and intermediate by-products. If left uncontrolled, the bacterial activity can cause the prevailing pH of the cooling water system to be significantly reduced. BRIEF SUMMARY A method of reducing activity of a bacteria, such as an oxidizing bacteria, is provided. The method includes adding a composition comprising an alkali metal salt of chlorite and/or an alkali metal salt of chlorate and hydrogen peroxide, to a process water of a cooling water system and increasing a concentration of the composition from about 0 ppm to about 300 ppm in about 1 to about 100 minutes. The process water comprises sulfur metabolizing bacteria, such as sulfur oxidizing bacteria, and/or nitrogen metabolizing bacteria. The term “metabolizing” covers all types of bacteria that can use any form of the ion, including oxidizing bacteria and reducing bacteria, such as sulfate reducing bacteria or a denitrifier that would reduce a nitrate to a nitrite, for example. In some aspects, the concentration of the composition increases from about 0 ppm to about 300 ppm in less than about 15 minutes. In some aspects, the concentration of the composition is increased from about 0 ppm to about 200 ppm. In some aspects, the concentration of the composition is increased from about 0 ppm to about 150 ppm. In some aspects, the method further includes decreasing a conductivity of the process water after adding the composition. In some aspects, the method further includes decreasing a sulfate, a nitrite, and/or a nitrate concentration in the proc