Editor’s Note: This article was originally published in July 2014 and has been updated with new information and reposted in Sep 2023.

Chemical waste from industrial manufacturing processes is often toxic and requires treatment before disposal. Aggressive chemicals represent a danger to local populations and the environment. An acid neutralization system adds chemicals to the chemical waste to reduce toxicity. When the right acid neutralization system is selected for a specific industrial process, the neutralized waste is often safe enough to flush down the municipal sewer.

Modutek designs and builds many types of chemical handling equipment, including self-contained acid neutralization systems that allow industrial customers to avoid using expensive third-party disposal companies. The systems Modutek provides are easy to install and feature low operating costs. They can be customized to match the customer application and fit available space. Such on-site chemical treatment and disposal is safe and cost-effective.

Understanding Acid Neutralization

Waste from industrial processes is often highly acidic—the liquid’s pH measures the waste’s acidity. A low pH means the waste contains strong acids and is highly corrosive. For example, an acidic sulfuric acid solution could have a pH of 3 and cause severe skin burns. The pH must be raised before the acidic waste can be disposed of safely.

A neutral pH of 7 is the pH of ordinary water, and a solution with a pH of 7 is no longer dangerous. The acid neutralization system must add enough alkaline chemicals to the acid waste to raise the pH to a safe level. A typical target pH of 6 to 9 is considered safe for disposal in the local sewer system.

Continuous Flow Systems versus Batch Neutralization Systems

Chemical waste can be neutralized continuously or in smaller batches. For continuous flow systems, the neutralizing chemicals are constantly added as the waste flow exits the process. The outflow is monitored to ensure that the pH remains within acceptable levels. For batch neutralizing systems, the chemical waste is collected and held in a collection containment tank. Once a given quantity is stored, the required neutralizing chemicals are added, and batch disposal can occur once the target pH is reached.

Continuous flow systems are most effective when the flow is relatively stable in terms of volume, pH, and nature of the waste chemicals. If significant variations occur, the continuous flow system may not be able to keep up, and impermissible values of pH may be reached in the outflow. Even when the outflow is relatively constant, the outflow pH may vary to some extent, so continuous flow systems are unsuitable when the outflow pH has to be within a narrow range.

Batch neutralization systems are lower cost but are focused more on applications with low volumes. The neutralization can be executed depending on the batch’s composition, and exact pH values can be attained. When waste is highly acidic or alkaline, batch neutralization systems can be more easily adapted to actual needs. In some applications, batch neutralization systems are the better choice.

Modutek Offers Systems that are Customized to Specific Applications

Modutek continuous flow acid neutralization systems can handle from 5 to 500 GPM and are available with two or three-stage operation, depending on the details of the process. The systems are unitized with larger systems skid-mounted for indoor or outdoor operation. Controls are fully automatic with microprocessor-based pH controls and a strip chart recorder. Chemicals are injected via two metering pumps per stage, and alarms can be sent remotely via the Internet. A final sample tank has a pH probe and chart recorder to document compliance with regulations.

Modutek’s batch sequence reactor systems can treat chemical waste, including heavy metals, metal anions, fluorides, and chelated/complex metals. Reactions can be programmed for multiple reagents and sequences. The systems are built with double containment and leak detection, and the contents of the built-in holding tank can be processed automatically. Safe operation is monitored with alarms for high and low pH, low reagent levels, high tank levels, and leakage. Modutek’s batch neutralization systems are designed for demanding chemical waste treatment and are the preferred option for process outflow with greatly varying characteristics.

Choosing the Right Neutralization System is Important for Environmental Protection

Selecting an acid neutralization system unsuitable for the process can have severe consequences both from a regulatory and environmental point of view. Modutek offers a free consultation to ensure that the chosen neutralization system is suitable for the application and performs as expected. Contact Modutek for recommendations on selecting the right acid neutralization system for your process application.