Patent Publication Number: US-2012024784-A1

Title: Fluid Gasification/Degasification Apparatuses, Systems, and Processes

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/369,146 filed on Jul. 30, 2010, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Wastewater—which may include any water that has been adversely affected in quality by anthropogenic influence—is typically subjected to various physical, biological, and chemical treatment processes in order to eliminate or significantly reduce various contaminants present therein, including potentially pathogenic microorganisms and/or harmful chemicals. Wastewater subjected to such treatment processes often must be further treated in order to render it suitable for consumption as drinking water. For example, treatment processes may be performed within basic pH ranges, requiring a lowering of the pH to within an acceptable range for human consumption. 
     The dissolution of acids in a solution can lower the pH of the solution by increasing the concentration of hydronium ions present therein. Acidic compounds may directly dissolve in solution while non-acidic compounds may react with other species present in the solution to form acidic products that lower the solution pH. 
     SUMMARY 
     Apparatuses, systems and processes for the gasification and/or degasification of a fluid are disclosed. Apparatuses and systems according to embodiments of the invention yield significant advantages over conventional apparatuses and systems, and may be used to chemically alter a fluid stream. For example, apparatuses and systems according to embodiments of the invention may be used to precisely adjust the pH of a fluid stream. 
     In accordance with one or more embodiments of the invention, a fluid gasification/degasification apparatus comprises housing comprising a vertically aligned central axis that extends between a top portion and a bottom portion of the housing and at least one fluid inlet and at least one fluid outlet positioned at different axial locations along the housing; a membrane unit disposed within the housing and comprising a plurality of bundled microporous hollow fiber membrane strands extending parallel to the central axis of the housing, each membrane strand comprising an outer shell having an inner diameter defining a lumen, the outer shell having a plurality of pores formed therein; and one or more gas addition/removal apparatuses for facilitating at least one of: a gas addition operation and a gas removal operation. During the gas addition operation, a carrier fluid supplied to the housing interfaces at or near at least one of the plurality of pores with micro-bubbles of a gas supplied to the membrane unit. In addition, an orientation of the at least one fluid inlet and the at least one fluid outlet results in a substantial portion of the carrier fluid traveling parallel to exterior surfaces of the membrane unit thereby allowing for an extended interface time between the carrier fluid and the micro-bubbles of the supplied gas. 
     Each gas distribution/removal apparatus may be provided at or near the top portion or the bottom portion of the housing and comprises a microporous hollow tubular structure comprising an outer shell having a plurality of pores formed therein and an inner diameter defining a lumen. The hollow tubular structure extends into the housing and through a cavity formed between an end cap of the housing and an upper surface of the membrane unit and further extends into at least a portion of the membrane unit. 
     The gas addition operation comprises introducing the supplied gas at a specified pressure into the hollow tubular structure. Upon introduction to the hollow tubular structure, the supplied gas undergoes a distribution stage and a diffusion stage. During the distribution stage, the supplied gas diffuses from a lumen side of the hollow tubular structure into the cavity through at least one of the plurality of pores formed in the outer shell of the hollow tubular structure, and moves therefrom into the lumen of at least one membrane strand of the membrane unit. During the diffusion stage, micro-bubbles of the supplied gas diffuse from a lumen side to a shell side of the at least one membrane strand through at least one pore formed in an outer shell thereof and interface with the carrier fluid to generate a chemically altered carrier fluid solution. 
     The gas removal operation may comprise generating a pressure differential between the lumen side and the shell side of at least one membrane strand of the membrane unit, thereby lowering a partial pressure of a gas dissolved in the carrier fluid and facilitating mass transfer of the dissolved gas from the carrier fluid to generate a chemically altered carrier fluid solution. The gas removal operation may additionally or alternatively comprise supplying an inert gas to the lumen of the at least one membrane strand of the membrane unit, thereby generating a concentration gradient of the dissolved gas between the lumen side and the shell side of the at least one membrane strand and facilitating mass transfer of the dissolved gas from the carrier fluid to generate the chemically altered carrier fluid solution. 
     A system for chemical alteration of a fluid stream comprises one or more fluid gasification/degasification apparatuses according to one or more embodiments of the invention; a gas transport and dosing system for transporting at least one of: the supplied gas and the inert gas from one or more storage receptacles to the one or more gas addition/removal apparatuses of each of the one or more fluid gasification/degasification apparatuses; and a control system for controlling a mass flow rate of at least one of: the supplied gas and the inert gas into the one or more gas addition/removal apparatuses of each of the one or more fluid gasification/degasification apparatuses in dependence on one or more process parameters, wherein the chemically altered carrier fluid solution generated by the one or more fluid gasification/degasification apparatuses is combined with the fluid stream to generate a chemically altered fluid stream. 
     The control system comprises a user interface for inputting the one or more process parameters; a system controller that analyzes the inputted parameters to determine an initial mass flow rate for at least one of: the supplied gas and the inert gas, one or more mass flow metering instruments for measuring a mass flow rate of at least one of: the supplied gas and the inert gas; and a chemical analyzer for measuring a parameter indicative of a chemical alteration of the chemically altered fluid stream. Additional chemical analyzers may be provided for measuring parameters indicative of chemical alterations of other fluid streams. 
     The system controller communicates the determined initial mass flow rate to at least one mass flow valve provided as part of the gas transport and dosing system, which controls introduction of at least one of: the supplied gas and the inert gas into the one or more gas distribution/removal apparatuses of each of the one or more fluid gasification/degasification apparatuses based on the communicated initial mass flow rate, and the system controller adjusts the initial mass flow rate based on at least one of: the measured parameter communicated by the chemical analyzer and the measured mass flow rate in order to achieve a desired chemical alteration of the chemically altered fluid stream. 
     In accordance with one or more embodiments of the invention, a process for chemically altering a first fluid stream comprises: providing at least one fluid gasification/degasification apparatus according to one or more embodiments of the invention, diverting at least a portion of the first fluid stream as a first side stream; introducing the first side stream to the at least one fluid gasification/degasification apparatus, wherein a fluid pressure of the first side stream is increased to compensate for a pressure drop that occurs as the first side stream passes through the at least one fluid gasification/degasification apparatus; facilitating at least one of: the gas addition operation and the gas removal operation to generate a chemically altered first side stream; and introducing the chemically altered first side stream into the first fluid stream to generate a chemically altered first fluid stream. The chemically altered first side stream generally has a fluid pressure substantially equal to a fluid pressure of the first fluid stream. 
     These and other embodiments of the invention are described in greater detail through reference to the following drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a schematic representation of a system for chemical alteration of a fluid stream in accordance with one or more embodiments of the invention. 
         FIG. 1B  shows a schematic representation of a system for chemical alteration of a fluid stream in accordance with one or more additional embodiments of the invention. 
         FIG. 2A  shows a fluid gasification/degasification apparatus in accordance with one or more embodiments of the invention. 
         FIG. 2B  shows a cross-sectional view of a hollow fiber membrane strand in accordance with one or more embodiments of the invention. 
         FIG. 2C  shows a side view of a hollow fiber membrane strand in accordance with one or more embodiments of the invention. 
         FIG. 2D  shows a detailed cross-sectional view of a gas addition/removal apparatus in accordance with one or more embodiments of the invention. 
         FIG. 2E  shows a schematic view of a system for dual gas addition/removal in accordance with one or more embodiments of the invention. 
         FIG. 3  shows a flowchart illustrating a process for chemically altering a fluid stream in accordance with one or more embodiments of the invention. 
         FIG. 4  shows a schematic representation of a system for chemical alteration of a fluid stream in accordance with one or more embodiments of the invention along with associated pHs, pressures and flow rates of various fluid streams. 
         FIGS. 5A and 5B  show experimental data in graphical form that demonstrates the greater efficacy of apparatuses according to embodiments of the invention as compared to conventional apparatuses. 
         FIG. 6  shows a schematic view of a fluid gasification/degasification apparatus in accordance with one or more additional embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention relate to apparatuses, systems and processes for gasifying and/or degasifying a fluid. In accordance with one or more embodiments of the invention, a fluid gasification/degasification process is disclosed, which may be employed for chemical alteration of a fluid stream such as, for example, to alter the pH of a fluid stream. 
     The process utilizes a fluid gasification/degasification apparatus that comprises housing having a vertically aligned central axis that extends between a top portion and a bottom portion of the housing and at least one fluid inlet and at least one fluid outlet positioned at different axial locations along the housing, a membrane unit disposed within the housing and comprising a plurality of bundled microporous hollow fiber membrane strands extending parallel to the central axis of the housing, each membrane strand comprising an outer shell having an inner diameter defining a lumen, the outer shell having a plurality of pores formed therein; and one or more gas addition/removal apparatuses for facilitating at least one of: a gas addition operation and a gas removal operation. 
     During the gas addition operation, a carrier fluid supplied to the housing interfaces at or near at least one of the plurality of pores with micro-bubbles of a gas supplied to the membrane unit as the micro-bubbles diffuse through the membrane unit. Mixing (and potential reaction) of the supplied gas and the carrier fluid generates a chemically altered carrier fluid solution. The chemically altered carrier fluid solution may then be combined with a fluid stream to yield a chemically altered fluid stream. In more specific embodiments of the invention, the chemically altered carrier fluid solution may have an adjusted pH, resulting in an adjustment of the pH of the fluid stream upon introduction of the chemically altered carrier fluid solution to the fluid stream. However, in other embodiments of the invention, the chemical alteration may relate to a chemical characteristic or property of the fluid(s) other than pH such as, for example, a dissolved concentration of oxygen in the fluid. Further, in various embodiments, an orientation of the at least one fluid inlet and the at least one fluid outlet results in a substantial portion of the carrier fluid traveling parallel to exterior surfaces of the membrane unit thereby allowing for an extended interface time between the carrier fluid and the micro-bubbles of the supplied gas. 
       FIG. 1A  depicts a schematic representation of a system for chemical alteration of a fluid stream. While  FIG. 1A  will be described with respect to specific embodiments of the invention involving pH adjustment of a fluid stream; the invention is not so limited, and the system may be employed to alter chemical characteristics or properties of a fluid stream other than pH. 
     The system  100  includes a fluid source  105  from which fluid stream  130 A is generated. A side stream  130 B may be diverted from fluid stream  130 A to form at least a portion of carrier fluid  130 C. A flow rate of side stream  130 B may be controlled via valve  135 A. Carrier fluid  130 C may be injected by pump  120  into fluid gasification/degasification apparatus  125  which increases and/or reduces the concentration of dissolved gas in the carrier fluid  130 C. A fluid pressure of carrier fluid  130 C may be increased prior to introduction to apparatus  125  so as to compensate for a pressure drop that occurs as the carrier fluid  130 C passes through the apparatus  125 . This ensures that a fluid pressure of the chemically altered carrier fluid solution  130 F is substantially equal to a fluid pressure of fluid stream  130 A, thereby facilitating introduction of the carrier fluid solution  130 F into the fluid stream  130 A. In accordance with one or more embodiments of the invention, the fluid gasification/degasification apparatus  125  may be used to adjust a pH of carrier fluid  130 C through the addition and/or removal of one or more gases to/from carrier fluid  130 C. The fluid gasification/degasification apparatus  125  will be described in more detail hereinafter through reference to  FIGS. 2A-2E . While embodiments of the invention will be described primarily with respect to fluid gasification apparatuses and processes, it should be understood that those same apparatuses and processes are also capable of degasifying a fluid with only slight modifications to the apparatus and/or the process. 
     System  100  further comprises a gas transport and dosing system  136  and a control system  137 . The gas transport and dosing system  136  may comprise a gas source  110 , piping  138  for transporting gas from the gas source  110  to apparatus  125 , and valves  135 B,  135 C. The gas transport and dosing system  136  may further comprise a manual gas feed control valve (not shown) for dosing gas manually. Manual dosing of gas to the fluid gasification/degasification apparatus at a specified gas flow rate may also be achieved through a user interface provided as part of the control system (described below). Gas source  110  may comprise any receptacle suitable for containing and storing gaseous compounds such as, for example, one or more storage tanks. The size and design of the receptacles may be tailored to a particular application. For example, the storage tanks may range from small 450 lb. dewars to larger bulk gas storage systems that recapture essentially all gas lost during storage. If gas source  110  becomes depleted, the system  100  may comprise an alarm mechanism to notify an operator, and secondary gas sources such as secondary storage tanks may be provided to supply gas during replenishment of gas source  110 . 
     During the gas addition operation, carrier fluid  130 C mixes (and potentially reacts) with at least one gas supplied to apparatus  125 , thereby leading to gasification of the carrier fluid  130 C. As will be described in more detail through reference to  FIGS. 2D and 2E , as part of the gas addition operation, gas may be introduced to apparatus  125  through gas ports provided in proximity to a top portion and/or a bottom portion of the apparatus  125 . Valves  135 B,  135 C are provided to control a flow rate of gas to the apparatus  125 . The gas may be carbon dioxide, oxygen, hydrogen, or a combination thereof; however, it should be noted that embodiments of the invention are not so limited and any suitable gas or mixture(s) of gases may be used. According to one or more embodiments of the invention, a suitable gas or mixture of gases may be any gaseous compound(s) that results in a suitable level of gaseous concentration of the carrier fluid  130 C, a suitable degree of chemical alteration of carrier fluid  130 C (e.g. pH adjustment) upon mixing of the gas and the carrier fluid  130 C, and/or a suitable degree of chemical alteration (e.g. pH adjustment) of a fluid stream into which the chemically altered fluid solution  130 F is introduced. 
     As will be described in more detail through reference to  FIG. 2D , as part of the gas addition operation, gas is supplied at a specified pressure into one or more gas addition/removal apparatuses, each being provided at or near a top portion or a bottom portion of the housing of fluid gasification/degasification apparatus  125 . More specifically, the gas is introduced into a hollow tubular structure of the gas additional/removal apparatus and proceeds to undergo a distribution stage and a diffusion stage. During the distribution stage, the supplied gas diffuses from a lumen side of the hollow tubular structure through at least one of a plurality of pores formed in an outer shell thereof into a cavity formed between an end cap of the housing and an upper surface of the membrane unit. The gas is then distributed or distributes itself from the cavity into the lumina of the membrane strands of which the membrane unit is comprised. During the diffusion stage, micro-bubbles of the supplied gas diffuse from a lumen side to a shell side of the membrane strands through the pores formed in the outer shells thereof and interface with the carrier fluid to generate the chemically altered carrier fluid solution  130 F. 
     Mixing of the micro-bubbles of the supplied gas and carrier fluid  130 C produces a solution  130 F of the carrier fluid having the gas dissolved therein which may then be combined with fluid stream  130 A. A side stream  130 G may be diverted from the carrier fluid solution  130 F and subjected to various treatment processes. In accordance with one or more embodiments of the invention, carrier fluid solution  130 F may have an adjusted pH as compared to the pH of the carrier fluid  130 C prior to introduction to apparatus  125 , and as such, addition of the carrier fluid solution  130 F to fluid stream  130 A may result in an adjustment of the pH of fluid stream  130 A. Fluid stream  130 H having an adjusted pH may then be introduced to another fluid stream, resulting in an adjustment of the pH of that fluid stream. In addition, side stream  130 G, which may be diverted from carrier fluid solution  130 F, may be introduced into an alternate fluid stream (not shown). Further, the combination of any number of fluid streams in order to achieve a desired effect (e.g. pH adjustment) is within the scope of this disclosure. Any of the fluid streams having an adjusted pH may have a pH in the range of about 2.0 to about 14.0. 
     Gasification/degasification apparatus  125  may also be used to perform a gas removal operation in which mass transfer of a gas dissolved in the carrier fluid  130 C is facilitated, thereby resulting in a reduced concentration of the dissolved gas. The gas removal operation may comprise generating a pressure differential between the lumen side and the shell side of at least one membrane strand of the membrane unit, thereby lowering a partial pressure of the gas dissolved in the carrier fluid  130 C and facilitating mass transfer of the dissolved gas from the carrier fluid  130 C to generate the chemically altered carrier fluid solution  130 F. For example, the pressure within the lumina of the membrane strands may be reduced (potentially to a near vacuum) leading to the formation of a dissolved gas concentration gradient across the outer shells of the membrane strands which in turn forces the dissolved gas out of solution. The gas then diffuses through the pores formed in the outer shells of the membrane strands and is removed via the one or more gas addition/removal apparatuses. 
     In conjunction with the generation of a pressure differential, or as an alternative thereto, an inert gas may be supplied to the membrane unit at a specified pressure via the one or more gas addition/removal apparatuses to in order to facilitate removal of gas from the carrier fluid. The inert gas may be supplied from gas source  110  or from an alternate gas source (not shown). More specifically, the inert gas may be supplied to the lumen of at least one membrane strand of the membrane unit, thereby generating a concentration gradient of the dissolved gas between the lumen side and the shell side of the at least one membrane strand and facilitating mass transfer of the dissolved gas from the carrier fluid to generate the chemically altered carrier fluid solution  130 F. Similar to the gas addition operation, mass transfer (i.e. removal) of dissolved gas from the carrier fluid  130 C may generate a carrier fluid solution  130 F having an adjusted pH which may then be combined with another fluid stream (e.g. fluid stream  130 A) to generate a pH adjusted fluid stream (e.g.  130 H). 
     In accordance with one or more embodiments of the invention, a secondary fluid stream  130 D may be generated from a secondary fluid source  115 . A secondary side stream  130 E may be diverted from the secondary fluid stream  130 D to form at least part of the carrier fluid  130 C. A flow rate of the secondary fluid stream  130 D may be controlled by valve  135 D. Use of a secondary side stream  130 E to form at least part of the carrier fluid  130 C may be particularly advantageous in treatment applications having high TSS or contaminants. In various embodiments, the secondary fluid stream  130 D may correspond to the effluent stream from one or more treatment systems. In alternate embodiments, the secondary side stream  130 E may be diverted from a fluid stream  130 D better suited for flow through the membrane unit. In certain embodiments, secondary side stream  130 E may be combined in any proportion with side stream  130 B to form carrier fluid  130 C, while in other embodiments, secondary side stream  130 E alone or side stream  130 B alone may form the carrier fluid  130 C. 
     Valves for controlling the flow rates of various fluid streams may be provided at various positions in the system depicted in  FIG. 1A . For example, valves  135 A and  135 D are positioned so as to control the flow rate of side stream  130 B and the flow rate of secondary side stream  130 E, respectively. Valve  135 E is provided to control the flow rate of the chemically altered carrier fluid solution  130 F that exits apparatus  125 . 
     The control system  137  comprises a user interface  139 , a system controller  141 , one or more mass flow metering instruments  143  for measuring a mass flow rate of the gas supplied to apparatus  125  during the gas addition operation and/or a mass flow rate of the inert gas supplied to apparatus  125  during the gas removal operation, and a chemical analyzer  145  for measuring a parameter indicative of a chemical alteration of a fluid stream. In one or more specific embodiments of the invention, the chemical analyzer  145  may be a pH probe that measures a pH of a fluid stream. 
     The user interface  139  may be a human-machine interface (HMI) of any suitable type (e.g. a touch-screen interface) and the system controller  141  may be, for example, a programmable logic controller. User interface  139  provides an operator with the capability to input one or more process parameters based on the specific requirements of the particular application for which the system is being used. The one or more process parameters may include a desired chemical alteration of carrier fluid  130 C and/or fluid stream  130 A (e.g. a desired pH for the carrier fluid solution  130 F and/or a desired pH for fluid stream  130 H). The one or more process parameters may further include a specified interface time between the carrier fluid  130 C and the diffused gas, a fluid flow resulting from a booster pump feeding the membrane unit, and/or a discharge pressure after the membrane unit. 
     System controller  141  analyzes the inputted process parameters to determine an initial mass flow rate for gas introduced to apparatus  125 . This initial mass flow rate is communicated to one or both of valves  135 B,  135 C, which in turn control the flow rate of gas introduced to the apparatus  125  based on the communicated initial mass flow rate. It should be noted that the initial mass flow rate may—as part of the gas removal operation—correspond to an initial rate at which the inert gas is supplied to the fluid gasification/degasification apparatus. 
     The mass flow metering instruments  143  are shown in  FIG. 1A  disposed between valve  135 B and apparatus  125  and between valve  135 C and apparatus  125 . However, the mass flow metering instrument(s)  143  may be disposed at any location in the gas feed line to the membrane unit prior to injection of gas into the membrane unit. That is, the mass flow metering instrument(s)  143  may be disposed anywhere between gas source  110  and apparatus  125 . Metering instruments  143  measure the mass flow rate of gas introduced to apparatus  125  and communicate the measured mass flow rate as an input parameter to system controller  141 . In certain embodiments of the invention, metering instruments  143  may also measure a mass flow rate of gas removed from the carrier fluid via apparatus  125 . 
     The following discussion relates to those embodiments in which the chemical analyzer  145  is a pH probe; however, as previously noted, the chemical analyzer may be any device that measures a parameter indicative of a chemical alteration of a fluid stream (e.g. a device that measures a concentration of dissolved gas). The pH probe  145  may be disposed so as to measure the pH of fluid stream  130 H (i.e., the stream that results from the introduction of the carrier fluid solution  130 F to fluid stream  130 A). In various embodiments of the invention, addition chemical analyzers  145  may be provided. For example, additional pH probes  145  may be provided to measure the pHs of additional fluid streams such as, for example, side stream  130 B, secondary side stream  130 E, pH adjusted carrier fluid solution  130 F prior to introduction into fluid stream  130 A, etc. The measured pHs may then be communicated as input parameters to system controller  141 . Based on one or both of the measured pH and the measured mass flow rate of gas, system controller  141  may modulate the mass flow rate of gas to apparatus  125  by controlling one or both of valves  135 B,  135 C as necessary to achieve a desired result (e.g. a desired pH for a fluid stream). In scenarios that require dynamic gas dosing, an operator may employ user interface  139  to manually adjust the mass flow rate of gas injected into apparatus  125 . In various alternate embodiments, gas dosing may be manually controlled via manual gas valve independently of the mass flow metering instruments  143  and the user interface  139 . 
     Mass flow metering instruments  143  and chemical analyzer  145  are two types of sensing/measurement devices that may supply feedback data to system controller  141 . However, any suitable sensor/measurement device may be provided at any number of positions within the system/process flow depicted in  FIG. 1  to measure process parameters and provide feedback to system controller  141  in order to obtain a desired chemical alteration (e.g. a desired pH for a fluid stream). 
     According to one or more embodiments of the invention, certain elements of system  100  described as being part of the gas transport and dosing system  136  (e.g. valves  135 B,  135 C) may instead be considered as part of the control system  137 . Similarly, certain elements described as being part of the control system  137  (e.g. mass flow metering instruments  143 ) may be considered as part of the gas transport and dosing system  136 . Moreover, in certain embodiments of the invention, various elements may be thought of as part of both the control system  137  and the gas transport and dosing system  136  simultaneously. That is, in certain embodiments of the invention, sub-systems may be distinct from each other and share no common structural elements, while in other embodiments, sub-systems may have shared structural elements. 
       FIG. 1B  schematically depicts a system  150  for carrying out a process for chemically altering a fluid stream using a gasification/degasification apparatus in accordance with one or more additional embodiments of the invention. While  FIG. 1B  will be described through reference to specific embodiments involving pH adjustment of a fluid stream, the process may be applied to alter a chemical characteristic or property of a fluid other than pH. 
     System  150  is similar to system  100  depicted in  FIG. 1  in many respects, and one or ordinary skill in the art will understand that any components of system  150  not specifically addressed or elaborated upon with respect to system  150  correspond substantially in structure and function to similar components discussed in relation to system  100 . 
     Among the ways in which system  150  differs from system  100  is in the subsequent treatment and use of pH adjusted fluid stream  160 B, which corresponds to fluid stream  160 A after pH adjusted carrier fluid solution  165 C is introduced thereto. Fluid stream  160 B is subjected to one or more treatment processes in treatment system  185 , and subsequently, a side stream  165 B of the treated fluid stream  160 C may be used to form at least part of the carrier fluid  165  introduced to gasification/degasification apparatus  175 . 
     Treatment system  185  may in practice be a combination of one or more treatment subsystems that subject fluid stream  160 B to one or more treatment processes for the removal of, for example, organic or inorganic contaminants from the fluid stream. Alternatively, the one or more treatment processes may be any number of physical, biological, or chemical treatment processes which a fluid stream may be subjected to at any stage in its overall treatment. 
     System  150  comprises a gas transport and dosing system  186  and a control system  187  that correspond substantially in structure and function to the gas transport and dosing system  136  and control system  137  of the system  100  depicted in  FIG. 1 . Similar to the gas transport and dosing system  136  of system  100 , the gas transport and dosing system  186  comprises a gas source  180 , piping  182  for transporting gas from the gas source  180  to apparatus  175 , and valves  183 A,  183 B. The gas transport and dosing system  186  may further comprise a manual gas control valve (not shown) for dynamically/manually controlling gas injection Like gas source  110 , gas source  180  may comprise any receptacle suitable for containing and storing gaseous compounds. 
     The control system  187  comprises a user interface  192 , a system controller  194 , one or more mass flow metering instruments  196  for measuring a mass flow rate of gas to/from apparatus  175 , and a chemical analyzer (e.g. a pH probe)  198  for measuring a parameter indicative of a chemical alteration (e.g. a pH) of a fluid stream. As with system  100 , user interface  192  provides an operator with the capability to input one or more process parameters which system controller  194  analyzes to determine an initial mass flow rate for gas introduced to apparatus  175 . This initial mass flow rate is communicated to one or both of valves  183 A,  183 B which control the flow rate of gas to apparatus  175  based on the communicated initial mass flow rate. In one or more specific embodiments of the invention, the one or more process parameters may include a desired pH for the carrier fluid solution  165 C and/or a desired pH for fluid stream  160 B. The desired pH for the carrier fluid solution  165 C and/or fluid stream  160 B may be in the range of about 2.0 to about 14.0. 
     Mass flow metering instrument(s)  196  are shown in  FIG. 1B  disposed between valve  183 B and apparatus  175  and between valve  183 A and apparatus  175 . However, the mass flow metering instrument(s)  196  may be disposed at any location in the gas feed line to the membrane unit prior to injection of gas into the membrane unit. That is, the mass flow metering instrument(s)  196  may be disposed anywhere between gas source  180  and apparatus  175 . The metering instrument  196  measures the mass flow rate of gas introduced to apparatus  175  and communicates the measured mass flow rate as an input parameter to system controller  194 . 
     The chemical analyzer (e.g. pH probe)  198  may be disposed, for example, in fluid stream  160 B. As in the embodiment depicted in  FIG. 1 , additional chemical analyzers may be provided. For example, additional pH probes  198  may be provided to measure the pHs of additional fluid streams such as, for example, fluid stream  160 A, side stream  165 A, secondary side stream  165 B, etc. The pH probe  198  measures the pH of fluid stream  160 B and communicates the measured pH as an input parameter to system controller  194 . In response to the measured pH and/or mass flow rate measurements, system controller  194  may modulate the mass flow rate of gas by controlling one or both of valves  183 A,  183 B to increase or decrease the flow rate of gas to apparatus  175  as necessary to achieve a desired chemical alteration (e.g. a desired pH for fluid stream  160 B). In scenarios that require dynamic gas dosing, an operator may employ user interface  192  to manually adjust the mass flow rate of gas injected into apparatus  175 . In various alternate embodiments, gas dosing may be manually controlled via a manual gas valve independently of the mass flow metering instruments  196  and the user interface  192 . 
     In one or more embodiments of the invention, the pH probe  198  may be disposed downstream from where the pH adjusted carrier fluid solution  165 C is introduced into fluid stream  160 A to form fluid stream  160 B. In more specific embodiments of the invention, pH probe  198  may be disposed downstream from treatment system  185 . By virtue of its placement downstream from treatment system  185 , pH probe  198  encounters a cleaner fluid stream (i.e. treated fluid stream  160 C) rather than fluid stream  160 B immediately upstream from treatment system  185 , thereby ensuring greater long-term viability of the probe and less maintenance. 
     After fluid stream  160 B is subjected to treatment in treatment system  185  to yield a secondary fluid stream  160 C, a secondary side stream  165 B may be diverted from the secondary fluid stream  160 C to form at least part of the carrier fluid  165 . Secondary fluid stream  160 C may undergo further treatment and/or discharge. Secondary side stream  165 B may be introduced into apparatus  175  as at least a portion of carrier fluid  165 . Side stream  165 A which is diverted from fluid stream  160 A and/or secondary side stream  165 B which is diverted from fluid stream  160 C may be combined in any proportion to form carrier fluid  165 . Further, either of the side streams may represent about 1% to about 75% of the total flow of the liquid stream from which the side stream was diverted (i.e. fluid stream  160 A and secondary fluid stream  160 C, respectively). 
     Referring to  FIG. 2A , a fluid gasification/degasification apparatus  200  in accordance with one or more embodiments of the invention includes housing  205  that includes a top portion  210 , a bottom portion  215 , and a vertically aligned central axis  220  that extends between the top portion  210  and the bottom portion  215 . The housing  205  further includes a fluid inlet  230  and a fluid outlet  235  that are positioned at different axial locations along the housing  205 . Although the inlet  230  and the outlet  235  are shown in  FIG. 2A  extending radially outwards from the housing  205  along axes that are 180 degrees apart, embodiments of the invention are not so limited and other inlet and outlet orientations are possible, including orientations in which the inlet and the outlet extend from the housing along respective axes that meet at an angle θ where 0°≦θ≦180° (or 360° depending on how the angle is measured). According to one or more particular embodiments of the invention, the inlet and outlet may be oriented so as to extend from the housing along respective axes that meet at an angle θ where 45≦θ≦135°. 
     In accordance with one or more embodiments of the invention, a carrier fluid  240  is pumped into the housing  205  through inlet  230  at or above system pressure. A fluid pressure of carrier fluid  240  may be increased prior to introduction to the housing  205  in order to compensate for a pressure drop that occurs as the carrier fluid  240  passes through the apparatus  200 . 
     The apparatus  200  may further include a membrane unit  254  disposed within the housing  205 . In certain embodiments of the invention, a plurality of membrane units may be employed in parallel or series configurations. The membrane unit  254  comprises a plurality of microporous hollow fiber membrane strands  250 , each membrane strand  250  being disposed within the housing  205  and extending in a direction substantially parallel to the central axis  220  of the housing  205 . Each hollow fiber membrane strand  250  may be formed from a polymer including a thermoplastic polymer such as a polypropylene or polyethylene material. The membrane unit  254  may comprise hundreds of tightly bundled hollow fiber membrane strands  250 . As a result of an orientation of the inlet  230  and the outlet  235 , at least a substantial portion of the carrier fluid  240  travels parallel to exterior surfaces of the membrane unit thereby allowing for an extended interface time between the first side stream and the micro-bubbles of the supplied gas. 
     Referring to  FIG. 2B , each hollow fiber membrane strand  250  may have a substantially cylindrical shape and comprise an inner diameter  250 A and an outer diameter  250 B. A width  250 C of an outer shell  251  of a membrane strand  250  is defined by the difference between the outer diameter  250 B and the inner diameter  250 A. Further, the inner diameter  250 A of a membrane strand  250  defines a lumen  252  of the strand  250 . Referring to  FIG. 2C , each membrane strand  250  includes micropores  253  formed in the outer shell  251 . The pores  253  are schematically shown in  FIG. 2C , and it should be understood that the pores  253  may be formed in the outer shell  251  in any number and/or arrangement. As a result of the small pore diameter, the microporous membrane strands  250  are permeable to molecules of at least one gas and substantially resistant to permeation of the carrier fluid molecules. The membrane strands  250  are permeable to, for example, carbon dioxide molecules which have a molecular diameter of approximately 0.00387 microns (3.87×10 −7  mm). The pores in the membrane strands  250  may be sized so as to be permeable to one or more gases and resistant to permeation of one or more carrier fluid compounds. A membrane that is formed of hollow membrane strands that are impermeable to water molecules may be referred to as a hydrophobic membrane. The membrane unit  254  may further comprise a filter (not shown) that protects the membrane from particulate damage, maintains efficiency, and improves the life expectancy of the membrane  254 . 
     Referring now to  FIGS. 2A-2C , as part of the gas addition operation, a gas or mixture of gases (e.g. carbon dioxide) is injected into a gas addition/removal apparatus provided at or near the top portion  210  and/or the bottom portion  215  of the housing  205 . As will be described in more detail through reference to  FIG. 2D , the gas addition/removal apparatus comprises a hollow tubular structure that extends into the housing  205  and partially extends into the membrane unit  254 . Gas introduced to the hollow tubular structure diffuses—as part of a distribution stage of the gas addition operation—through pores formed therein and into one or more cavities  255  and  256  provided between the membrane unit  254  and end caps  236  and  237 , respectively, of the housing  205 . The gas is then distributed or distributes itself across the membrane unit  254 , and in particular, into the lumina  252  of the membrane strands  250 . During the gas removal operation, the inert gas may be supplied to the gas addition/removal apparatus in a similar manner. 
     After the gas is introduced into the housing  205  and distributed through the lumina  252  of the plurality of membrane strands  250 , the gas undergoes a diffusion stage in which the gas travels through the lumina  252  and diffuses through the pores  252  formed in the outer shells  251  of the membrane strands  250 . More specifically, micro-bubbles of the gas diffuse through the pores  253  and interface with the carrier fluid  240  at or near the pores  253 . The micro-bubbles that diffuse through the pores  253  possess a high surface area to volume ratio that increases the relative surface area available for contacting the carrier fluid  240  is it travels from the inlet  230  of the housing  205  to the outlet  235 . As carrier fluid molecules and gas molecules interface, mixing and potential reaction occurs. In those embodiments of the invention in which the gas is carbon dioxide and the carrier fluid is water or is comprised primarily of water, water molecules and carbon dioxide molecules react almost instantaneously upon contact to form carbonic acid. 
     As previously mentioned, carrier fluid  240  may be pumped through the inlet  230  of the housing  205  at a slightly elevated fluid pressure in order to compensate for a pressure drop that occurs as the carrier fluid  240  passes through the fluid gasification/degasification apparatus. However, it is neither necessary nor desirable for the carrier fluid  240  to be pumped into the housing  205  at a highly elevated pressure that would yield a super-saturated carrier fluid solution. The pressure of the carrier fluid may, for example, be increased prior to introduction to the fluid gasification/degasification apparatus in order to compensate for a 5-20 psi pressure drop through the apparatus. This ensures that the chemically altered carrier fluid solution has a fluid pressure substantially equal to the fluid stream to which it is introduced. 
     As previously noted, an orientation of the fluid inlet  230  and the fluid outlet  235  results in a substantial portion of the carrier fluid  240  traveling parallel to exterior surfaces of the membrane unit  254  thereby allowing for an extended interface time between the carrier fluid  240  and the micro-bubbles of the supplied gas. This parallel flow path  245  of the carrier fluid provides advantages over conventional apparatuses such as longer interface time between the carrier fluid and the supplied gas and additional mixing through fluid dynamics. After the carrier fluid  240  is introduced into the housing  205 , some portion of the carrier fluid  240  may initially travel across a width of the housing  205  (the width of the housing  205  being measured in a direction substantially perpendicular to the central axis  220  of the housing  205 ). In traveling across the width of the housing  205 , the carrier fluid molecules may travel around the exterior surfaces of the outer shells  251  of the hollow fiber membrane strands  250 , but generally do not permeate through the pores of the membrane strands due to the substantially resistant nature of the microporous membrane to permeation by carrier fluid molecules. 
     According to one or more embodiments of the invention, the membrane unit  254  may comprise hundreds of relatively tightly packed membrane strands. As such, the carrier fluid  240  generally will not travel through the membrane unit  254  (i.e. around exterior surfaces of the membrane walls  251  of hollow fiber membrane strands  250  located towards an interior of the membrane unit  254 ). That is, the carrier fluid  240  will generally travel along a parallel flow path that results in contact between carrier fluid molecules and gas molecules at or near pores of membrane strands  250  located towards or along an outer periphery of the membrane  254 . 
     Due to the substantially parallel flow path  245  shown in  FIG. 2A , both the area of contact and the duration of contact between carrier fluid molecules and supplied gas molecules is significantly increased relative to conventional apparatuses and methods. In conventional apparatuses, the carrier fluid traverses a tangential flow path across membrane fiber strands. Tangential flow of the carrier fluid reduces both the carrier fluid flow rate through the housing and the contact time between carrier fluid molecules and gas molecules that diffuse through the membrane strands. As such, fluid gasification/degasification apparatuses according to embodiments of the invention can achieve significantly higher carrier fluid flow rates and interface times than conventional apparatuses. 
     An apparatus in accordance with one or more embodiments of the invention may produce a carrier fluid flow rate of about 5.7×10 −2  to about 3.45 gpm (gallons per minute) per square foot of membrane surface area. This equates, for example, to 5-300 gallons per minute of flow for a 4 inch by 13 inch membrane unit having 87 square feet of surface area. It should be noted that embodiments of the invention are not limited to a membrane unit having a specific height and width. Membrane units of varying lengths and widths may be employed such as, for example, a 6 inch by 28 inch membrane unit. Further, according to one or more embodiments of the invention, the membrane unit (which includes a plurality of bundled membrane strands) is capable of achieving gas diffusion rates of about 1.15×10 −2  to about 11.49 standard cubic feet per hour (SCFH) per square foot of membrane surface area. This equates, for example, to 1-1000 SCFH of carbon dioxide for a 4 inch by 13 inch membrane unit having 87 square feet of surface area. One of ordinary skill in the art will appreciate that these dimensions and numerical figures are presented purely by way of example and are not intended to be limiting. Any membrane of any dimension, any suitable gas diffusion rate, and any suitable carrier fluid flow rate are encompassed by this disclosure. 
       FIG. 2D  provides a detailed cross-sectional view of a gas addition/removal apparatus in accordance with one or more embodiments of the invention. The gas addition/removal apparatus facilitates the introduction and/or removal of a gas to/from the fluid gasification/degasification apparatus. The gas addition/removal apparatus shown in  FIG. 2D  may be provided at or near a top portion or a bottom portion of the fluid gasification/degasification apparatus thereby providing for introduction/removal of gas from one or both longitudinal ends of the fluid gasification/degasification apparatus. 
     While operation of the gas addition/removal apparatus will be described through reference to a gas addition operation that forms part of a gasification process, it should be noted that the apparatus is also capable of facilitating a gas removal operation as part of a degasification process. More specifically, as part of the gas removal operation, the gas addition/removal apparatus may facilitate removal of dissolved gas, and potentially, introduction of an inert gas to the fluid gasification/degasification apparatus. 
     The gas addition/removal apparatus includes a hollow tubular structure  264  that extends into the housing  266 . The hollow tubular structure  264  includes a threaded portion  260  for connection to a gas supply source (not shown). At least one gas may be introduced into the hollow tubular structure  264 . A cavity  263  is formed between an end cap  262  of the housing  266  and the microporous membrane  267  by means of cylindrical spacer  265  that spaces the end cap  262  from the membrane  267 . As part of a distribution stage of the gas addition operation, the gas introduced into the hollow tubular structure  264  diffuses into the cavity  263  through pores  283  formed in the hollow tubular structure  264 . The gas is then actively distributed or distributes itself among the membrane strands of the membrane  267 , and more specifically, into lumina of the membrane strands. 
     Various O-ring seals  268  may also be provided to form a tight seal between the membrane  267  and the housing  266 . The seals  268  fully seal off the cavity  263  and ensure that gas molecules entering the hollow fiber membrane strands of the membrane  267  do not escape into other portions of the housing  266 . The membrane may include thickened portions  269 ,  280  provided on either side of the membrane along its width to seat or support the seals  268 . The gas addition/removal apparatus further includes a cap  281  provided to seal off an end of the hollow tubular structure  264  and may additionally include seals  282  provided circumferentially around the hollow tubular structure  264 . 
       FIG. 2E  depicts a schematic representation of gas addition/removal through ports provided at either longitudinal end of the gasification/degasification apparatus. Gas may be provided via a gas source  276  for introduction into the housing  277  through a port provided at or near a top portion  278  of the housing  277  and a port provided at or near a bottom portion  279  of the housing  277 . A gas addition/removal port may correspond to the gas addition/removal apparatus described through reference to  FIG. 2D . 
     Referring to  FIG. 2E , valves  272 ,  273  may be isolation valves that are capable of single and dual port gas addition. Closing of valve  272  and the opening of valve  273  permits gas addition through the port provided at or near the top portion  278  of the housing  277  (i.e. the port closest to the inlet  270 ) and prevents gas addition through the port provided at or near the bottom portion  279  of the housing  277 . Alternately, closing of valve  273  and the opening of valve  272  permits gas addition through the port provided at or near the bottom portion  279  (i.e. the port closest to the outlet  271 ) and prevents gas addition through the port provided at or near the top portion  278 . During gas addition/removal through the port closest to the outlet  271 , valve  274  is generally also in a closed position. However, valve  274  may be opened in order to flush out any fluid that is present in the hollow membrane fibers. Valve  274  may also be opened to allow for low volume gas flow through the full length of the membrane fibers, thereby increasing the efficiency of gas diffusion through the pores provided in the membrane walls of the membrane fibers. One or more mass gas flow metering devices  275  may be provided to measure a gas flow rate through one of more of the ports. 
     As noted earlier, apparatuses in accordance with various embodiments of the invention provide various advantages over conventional apparatuses. In particular, apparatuses, systems, and processes according to embodiments of the invention provide for increased area of contact and increased contact/interface time between the carrier fluid and the gas that diffuses or permeates through the pores of the membrane unit. The contact/interface time between the carrier fluid and diffused gas may be specified based on a desired chemical alteration of a fluid stream. For example, the interface time may be specified in order to achieve a desired adjusted pH for a fluid stream. The increased contact area and contact time result from one or more of the following: (1) increased carrier fluid flow rate, (2) an orientation of the fluid inlet and fluid outlet that directs the carrier fluid along a flow path that facilitates interfacing between the carrier fluid and the supplied gas and/or dissolved gas, and (3) the smaller volume (and consequently higher surface area to volume ratio) of gaseous micro-bubbles that diffuse through the pores formed in the outer shells of the membrane strands of the membrane unit. Although embodiments of the invention have been described primarily with respect to parallel carrier fluid flow paths, alternate non-rotational or non-circular flow paths are also within the scope of the invention. For example, the inlet and outlet of the housing of the fluid gasification/degasification apparatus may be oriented such that the carrier fluid is directed along a non-parallel, non-rotational flow path that provides the same advantages over conventional systems as the parallel flow path. 
     As noted earlier, conventional apparatuses generate substantially tangential carrier fluid flow across the membrane, which results in decreased flow rates, decreased contact area, and decreased contact time between carrier fluid molecules and gas molecules that diffuse through the membrane unit. Some conventional apparatuses employ larger membranes but continue to generate a tangential carrier fluid flow path. Further, certain conventional apparatuses employ a gas sparger that disperses gas in large bubbles into the carrier fluid. These apparatuses, however, suffer from the same drawbacks of reduced contact area and reduced contact time between gas molecules and carrier fluid molecules. In sharp contrast, apparatuses in accordance with various embodiments of the invention provide for increased contact time and increased surface contact area between carrier fluid molecules and gas molecules. The increased contact area and contact time increases the amount of interfacing/mixing between the gas and the carrier fluid, and consequently, the degree of gasification or degasification of the carrier fluid. Moreover, because apparatuses according to embodiments of the invention generate a parallel carrier fluid flow path rather than the tangential carrier fluid flow path observed in conventional apparatuses, significantly less stress on the membrane is observed during operation of apparatuses of the invention as compared to conventional apparatuses. In addition, less risk of damage to the membrane from the impact of foreign objects exists with apparatuses of the invention. 
     Applicants have conducted a series of experiments that compare the performance of apparatuses according to embodiments of the invention in which the carrier fluid flows along a parallel flow path with conventional apparatuses in which the carrier fluid flows along a tangential (perpendicular) flow path. As shown in  FIG. 5A , the parallel flow path apparatus demonstrated the largest adjustment (lowering) in carrier fluid solution pH over the same range of carbon dioxide gas flow rates. Moreover, referring to  FIGS. 5A and 5B , at a gas flow rate of 120 SCFH, the parallel flow path apparatus exhibited a lower carrier fluid solution pH (below 5.5) than the highest performing conventional perpendicular flow apparatus (above 5.5 with a 60 gpm carrier fluid flow rate and a 1.74 ms contact time). 
       FIG. 3  is a flow chart illustrating a fluid gasification process in accordance with one or more embodiments of the invention. Those of ordinary skill in the art will appreciate that with slight modifications (as described previously herein) the process depicted in  FIG. 3  can be used for fluid degasification. 
     In step S 300 , housing is provided. The housing may be, for example, housing in accordance with one or more embodiments of the invention described through reference to any of the previous Figures. In step S 301 , a membrane is provided or positioned within the housing. The membrane may be, for example, a membrane in accordance with one or more embodiments of the invention described through reference to any of the previous Figures. 
     In steps S 302  and S 303 , at least one gas is supplied to the housing and ultimately to the membrane unit via one or more gas addition/removal apparatuses (such as those previously described through reference to  FIGS. 2D-2E ), each of which may be provided at either longitudinal end of the housing. The gas supplied in step S 302  may be, for example, carbon dioxide; however, any suitable gas is within the scope of the invention. As described earlier through reference to  FIGS. 2A-2E , gas may be supplied to the membrane unit via a hollow tubular structure provided as part of the gas addition/removal apparatus. In particular, gas may enter a cavity formed between an end cap of the housing and the membrane unit via diffusion through pores formed in the hollow tubular structure. The gas may then be distributed or distribute itself into the lumina of the hollow fiber membrane strands that make up the membrane unit. 
     In step S 303 , a carrier fluid may be supplied through an inlet of the housing at or above source pressure. As carrier fluid is being introduced to the housing, in step S 304 , a flow path for the carrier fluid is generated that facilitates mixing of the carrier fluid and gas that has diffused through pores formed in the outer shells of the membrane strands of the membrane unit. More specifically, an orientation of the inlet and outlet may result in a substantial portion of the carrier fluid traveling parallel to exterior surfaces of the membrane unit thereby facilitating interfacing between the carrier fluid and the diffused micro-bubbles of gas at or near the pore interface. Mixing and potential reaction of the carrier fluid and the gas generates a carrier fluid solution having the gas dissolved therein. In embodiments of the invention in which the gas is carbon dioxide and the carrier fluid is water, carbonic acid is formed at a very high reaction rate which in turn lowers the pH of the carbon dioxide/water solution. 
     In step S 305 , the carrier fluid that is formed in step S 304 , exits the housing through an outlet formed in the housing and may be combined with another fluid stream. In accordance with one or more embodiments of the invention, upon mixing of the carrier fluid solution and the fluid stream, the fluid stream may be chemically altered (e.g. a pH of the stream may be lowered). Alternatively, the gasified carrier fluid (i.e. the carrier fluid solution) may be used for any other suitable purpose. 
       FIG. 4  depicts a system for fluid gasification/degasification similar to that depicted in  FIG. 1B .  FIG. 4  identifies the pressure, flow rate, and pHs of various fluid streams at various stages of the system/process flow of  FIG. 1B . It should be noted that although  FIG. 4  relates to those embodiments of the invention in which the gasified/degasified carrier fluid is used to alter the pH of a fluid stream, embodiments of the invention are not limited to pH adjustment. That is, the fluid gasification/degasification apparatuses according to embodiments of the invention may be used to alter chemical characteristics or properties of a fluid stream other than pH. 
     Referring to  FIG. 4 , fluid stream  410 A generated from fluid source  405  has an initial pressure P 0 , an initial flow rate F 0 , and an initial pH (pH 0 ). A side stream  415 A may be diverted from the fluid stream  410 A to form at least part of a carrier fluid  415 . Side stream  415 A has a pH (pH 1 ) that is typically equivalent to the initial pH (pH 0 ) of fluid stream  410 A. That is, absent minor fluctuations in pH caused by changes to external conditions, pH 0 =pH 1 . 
     Carrier fluid  415  is supplied via pump  420  to fluid gasification/degasification apparatus  425 . As part of a gasification process in apparatus  425 , carrier fluid  415  mixes (and potentially reacts) with at least one gas supplied from gas source  430  to generate a carrier fluid solution  415 C potentially having an adjusted pH. In particular, carrier fluid solution  415 C may have a pH (pH 3 ) that is less than pH 0  (and by extension pH 1 ). Solution  415 C is then introduced into fluid stream  410 A. Mixing of carrier fluid solution  415 C and fluid stream  410 A may result in an adjustment (e.g. lowering) of the pH of fluid stream  410 A. In particular, introduction of carrier fluid solution  415 C into fluid stream  410 A generates fluid stream  410 B having a pH (pH 4 ) that may be lower than pH 0 , which is the initial pH of fluid stream  410 A. However, pH 4  is typically higher than pH 3  due to the mixing of the lower pH solution  415 C with fluid stream  410 A having an initial pH of pH 0 =pH  1 . 
     Fluid stream  410 B having an adjusted pH of pH 4  is then subjected to one or more treatment processes in treatment system  435  to generate fluid stream  410 C having a pH (pH 6 ) that may be slightly altered compared to pH 4 . A side stream  415 B may be diverted from fluid stream  410 C to form at least part of carrier fluid  415 . Alternately, a secondary side stream  415 D may be generated from a secondary fluid source  445  to form at least part of carrier fluid  415 . Side stream  415 B may have a pH (pH 5 ) that is generally equivalent to the pH (pH 6 ) of fluid stream  410 C. However, both pH 5  and pH 6  may be slightly elevated compared to pH 4  if gas mixing occurs during the treatment process of treatment system  435 . Alternately, if secondary side stream  415 D constitutes the primary component of carrier fluid  415 , the pH of the secondary side stream  415 D (pH 5 ) may or may not differ from the pH (pH 6 ) of fluid stream  410 C. 
     Throughout the system/process flow depicted in  FIG. 4 , pH 0 =pH 1  is generally in the range of about 6.0 to about 14.0. The pH of the carrier fluid solution  415 C (pH 3 ) may generally be in the range of about 2.0 to about 14.0. Further, pH 4  which is generally equivalent to pH 5  and pH 6  (although, as noted above, pH 5  and pH 6  may be slightly elevated compared to pH 4 ) is typically in the range of about 2.0 to about 14.0. It should be noted that the foregoing pH ranges are presented only by way of example and should not be deemed as limiting the pH values that any of the fluid streams may possess at any stage of the system/process flow of  FIG. 5 . 
       FIG. 4  also identifies the flow rates of the various fluid streams and side streams. The following discussion with respect to flow rates is based on the assumption that either side stream  415 B alone (diverted from the fluid stream  410 C) forms carrier fluid  415  or side stream  415 A alone (diverted from fluid stream  410 A) forms carrier fluid  415 . However, it should be noted that this assumption is made solely to simplify the discussion with respect to variations in flow rates. For example, as shown in  FIG. 4 , a secondary side stream generated or diverted from a secondary fluid source  445  may be used to form at least part of carrier fluid  415 . In accordance with one or more embodiments of the invention, side stream  415 A, side stream  415 B, and secondary side stream  415 D may be combined in any proportion to form carrier fluid  415 . 
     In the scenario in which side stream  415 A alone forms carrier fluid  415 , the flow rate F 0  of fluid stream  410 A generated from fluid source  405  is greater than the flow rate F 1  of fluid stream  410 A after side stream  415 A is removed. Further, the flow rate F 4  of fluid stream  410 B (corresponding to fluid stream  410 A after introduction of carrier fluid solution  415 C) is generally equivalent to the initial flow rate F 0  of fluid stream  410 A and in turn is equivalent to the sum of flow rates F 1  and F 3 . Further, because side stream  415 B does not form part of the carrier fluid  415  in this scenario, its flow rate F 5  is zero and the flow rate F 6  of treated fluid stream  410 C is generally equivalent to flow rate F 4 . 
     In the scenario in which the side stream  415 B alone forms carrier fluid  415 , the initial flow rate F 0  of fluid stream  410 A is generally equivalent to flow rate F 1  because, in this scenario, side stream  415 A does not form part of carrier fluid  415 . Further, flow rate F 3  of carrier fluid solution  415 C is generally the same as flow rate F 5  of side stream  415 B that forms the carrier fluid  415 . The flow rate F 4  of fluid stream  410 B (corresponding to fluid stream  410 A after introduction of carrier fluid solution  415 C) is generally equivalent to the sum of flow rates F 0  and F 5  of fluid stream  410 A and side stream  415 B, respectively. In this scenario, as side stream  415 B is removed to form the carrier fluid  415 , the flow rate F 6  of fluid stream  410 C is generally equivalent to the difference between flow rate F 4  and flow rate F 5  of treated side stream  415 B. 
       FIG. 4  also identifies various pressures of fluid streams and side streams at different stages in the system/process flow. As similarly stated with respect to flow rates, the following discussion with respect to pressures is based on the assumption that either side stream  415 B alone (diverted from fluid stream  410 C) or side stream  415 A alone (diverted from fluid stream  410 A) forms carrier fluid  415 . However, it should be noted that this assumption is made solely to simplify the discussion with respect to variations in pressures. For example, as shown in  FIG. 4 , a secondary side stream generated or diverted from a secondary fluid source  445  may be used to form at least part of carrier fluid  415 . In accordance with one or more embodiments of the invention, side stream  415 A, side stream  415 B, and secondary side stream  415 D may be combined in any proportion to form carrier fluid  415 . 
     In the scenario in which side stream  415 A alone forms carrier fluid  415 , the pressure PO of fluid stream  410 A generated from the fluid source  405  is generally equivalent to the pressure P 1  of fluid stream  410 A after side stream  415 A has been removed, and is less than the pressure P 2  at which carrier fluid  415  is pumped into apparatus  425 . The pump  420  typically transfers the carrier fluid  415  into the apparatus  425  at a pressure P 2  equivalent to an increase in the initial pressure PO by about 5 to about 20 psi. The pump  420  is employed in order to compensate for the pressure loss that occurs as the carrier fluid flows through the apparatus  425  as well as to ensure that the pressure P 3  of the carrier fluid solution  415 C is substantially equal to the pressure P 1  of the fluid stream  410 A prior to introduction therein. Further, the pressure P 6  of fluid stream  410 C having undergone the treatment process of treatment system  435  is typically less than pressure P 4  as a result of a pressure drop that occurs across the treatment system  435 . 
     In the scenario in which side stream  415 B alone forms carrier fluid  415 , the pressure PO of fluid stream  410 A generated from fluid source  405  is generally equivalent to pressure P 1 , and is less than the pressure P 2  at which the carrier fluid  415  is pumped into apparatus  425 . The pump  420  typically transfers the carrier fluid  415  into the apparatus  425  at a pressure P 2  equivalent to an increase in the pressure P 5  of side stream  415 B by about 5 to about 20 psi. The pump  420  is employed in order to compensate for the pressure loss that occurs as the carrier fluid flows through the apparatus  425  as well as to ensure that the pressure P 3  of the carrier fluid solution  415 C exceeds the pressure P 1  of fluid stream  410 A prior to introduction of the solution  415 C into the fluid stream  410 A. In addition, the pressure P 3  of the carrier fluid solution  415 C is generally less than the pressure P 2  of the carrier fluid  415  prior to introduction into the apparatus  425  due to a pressure drop that occurs across the apparatus  425 . Further, the pressure P 6  of fluid stream  410 C as well as the pressure P 5  of side stream  415 B both may be less than pressure P 4  due a pressure drop that occurs across the treatment system  435 . 
       FIG. 4  has been provided to describe variations in pH, flow rate, and pressure that occur during a pH adjustment process in accordance with embodiments of the invention. It should be understood that although not explicitly shown in  FIG. 4 , the gas dosing system and control system described through reference to  FIGS. 1A and 1B  also form part of the system depicted in  FIG. 4 . 
       FIG. 6  schematically depicts a fluid gasification/degasification apparatus in accordance with one or more alternative embodiments of the invention. The apparatus  600  includes two fluid inlets  601 A,  601 B and a single fluid outlet  602 . It should be noted, however, that fluid gasification/degasification apparatuses in accordance with embodiments of the invention may include any number of fluid inlets and/or fluid outlets. By virtue of having two fluid inlets  601 A,  601 B, the apparatus  600  is capable of sustaining increased carrier fluid flow, which in turn decreases the amount of contact/interface time between the carrier fluid and the diffused gas necessary in order to achieve a desired chemical alteration (e.g. a desired adjusted pH). 
     While the invention has been described with respect to certain embodiments of the invention, other and further embodiments of the invention may be devised without departing from the spirit and scope of the invention. As such, the scope of the invention is determined by the claims that follow. The invention is not limited to the particularly described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.