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pH Neutralization Systems and Neutralizers

Autocalibrate™ (panel to left) is one of many advanced neutralizer options

Acidic or basic waste liquids from labs, industrial sources and rinsing operations can cause chemical attack on sewage pipes and operating problems in municipal waste treatment plants. Therefore regulations specify that waste liquids must be near neutral pH before they can be released into any public sewer.

The pH value of a neutral liquid is 7, and regulations generally specify an acceptable discharge pH range of 6 to 9. This often requires on-site neutralizing prior to discharge to sewer.

However, pH control around the neutral point (pH 7) is notoriously difficult due to the logarithmic nature of the pH scale. Many facilities that generate acidic or basic waste liquids turn to ChemIndustrial Systems Inc for specialized process equipment and controls required for successful neutralization.

ChemIndustrial’s Chemical Theory section contains a technical discussion of acid-base theory.

ChemIndustrial Neutralizers – Integrated pH neutralization systems

A ChemIndustrial neutralizer receives, samples, measures and controls the pH of liquid discharged from a facility, then discharges successfully treated liquid to sewer or a downstream process.

The ChemIndustrial neutralizer circulates a stream of liquid from a tank past a pH sensor, which automatically meters and mixes a neutralizing chemical into the circulating liquid by means of a venturi injector. Typically the neutralizer’s control system is configured to release liquid to sewer once pH is within the acceptable range.

A complete list of neutralizer features is found here..  

ChemIndustrial System’s Neutralizers are built in two basic configurations:

  1. One-way neutralization for correcting pH that always varies in the same direction from the required range
  2. Two-way neutralization for correcting pH that can vary either above or below the required range

ChemIndustrial neutralizers use reliable pumped venturi injection technology for chemical feed.  Sophisticated control algorithms intelligently adjust the amount of neutralizing chemical added to the process as the system’s pH approaches the neutralization point. Neutralizer controls are optimized for operation within the 6 to 9 pH range. For operation outside this pH range, ChemIndustrial’s pH control systems are recommended instead.

Typical neutralization configuration

A complete and detailed description of a typical skid-mounted neutralizer configuration is found here.

Larger neutralizing systems

ChemIndustrial skid-mounted neutralizers are sized for easy integration into many customer facilities, but a standard skid may not be large enough for high volume waste flows. When the flow of liquid for treatment exceeds the practical capacity of a skid, we turn to other strategies:

  • Add an inlet surge tank
    This is a good choice where inflows are variable, with periodic peak flows higher than a skid can handle but average flow within a skid’s treatment capacity.
  • Parallel skids
    Redundancy has its own value, so it may be desirable to increase capacity by adding neutralizing skids in parallel. ChemIndustrial’s networked control systems allow an array of strategies for functions such as tiered skid startups and lead/lag switching.
  • Split architecture neutralizing systems
    Where higher flow rates make skids impractical, a free-standing treatment tank of suitable capacity is used, with mechanical and control equipment located in clusters. ChemIndustrial remains true to its “skid philosophy” by combining process and control elements wherever possible.
Neutralization applications and flowsheets

ChemIndustrial’s neutralizing systems are ideal for a wide range of applications, including integration with a pre-existing sump or use in a ready-mix concrete facility. See examples of typical applications of ChemIndustrial’s neutralizers, including detailed drawings and flowsheets.

Additional options
  • AutoCalibrate™ – automated pH calibration
    Automatic calibration is the newest feature available on ChemIndustrial’s neutralizer and pH control systems. ChemIndustrial’s AutoCalibrate™ system simplifies pH control and neutralization by relieving operators of the need to manually calibrate the pH probe on a regular basis.
  • Recording options
    Many neutralizing system owners find it desirable to preserve a record of system operating performance. ChemIndustrial offers a range of recording options: circular chart recorders, free-standing paperless recorders or direct data transfer to a PC.
  • Outlet flow regulation
    In many cases the regulations specify a maximum discharge rate and an allowable daily discharge volume as well as the acceptable pH range. A ChemIndustrial outlet flow regulator deals with these issues.
  • ChemWand®
    ChemIndustrial one-way neutralizers include a ChemWand® drum feeder to supply acid or base reagent to the neutralizer.