Recent business publications reported that China's rapid growth in the industrial sector has resulted in a significant increase in the handling and neutralization of wastewater. This has created a need to take a careful look at chemical resistant pumps, valves, and other fluid transfer and storage equipment.

A report from the process control engineering company, Digital Analysis Corp., Skaneateles, N.Y., stated that their engineered wastewater treatment systems around the world are now treating more than 90 million gallons of hazardous industrial wastewater every day. Over the last dozen years these pH neutralization systems have treated more than 100 billion gallons of wastewater.

Company president Richard Pinkowski noted that these pH adjustment systems are needed to satisfy a growing demand to neutralize corrosive chemicals, generated in processing plants, so that they can be safely discharged to sanitary sewer systems, rather than hauled off the site. The systems are completely automated and feature at least two levels of redundancy to prevent accidental discharge of non-compliant wastes. In addition, all of these systems are PLC- (programmable logic control) based and can be monitored via phone line from anywhere in the world.

Pump and pipe material selection

Chem Gard CGA-PY4X3X10 pumps were chosen for their performance and chemical resistance.

The aggressive characteristics of the highly acidic or alkaline wastewater fluids from a petrochemical facility in China had to be neutralized before being discharged. They presented a problem of proper material selection for the fluid-handling equipment involved. Although metal components such as stainless steel and exotic alloys had originally been specified for this installation, they were ruled out by the system designers because their previous experience with handling hot, caustic or acidic wastes – with periodic sulfuric acid concentrations of up to 98 percent – indicated that only non-metallics could guarantee the long term reliability, safety and low maintenance the customers required. Thermoplastic materials such as polypropylene (PP), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) and polyvinylidene fluoride (PVDF) were chosen for all-fluid contact components. The custom-fabricated tanks were constructed from polypropylene. CPVC was used for the piping, valves and fittings.

Of particular concern was the design and material selection for the pumps, which would be subjected to very high duty cycles and harsh ambient conditions. Thermoplastic pumps manufactured by Vanton Pump and Equipment Corp., Hillside, N.J., were chosen based on their history with the safe handling of corrosive fluids.

The end-suction pumps combined with a centerline discharge and back pullout in a power frame design featuring a sliding bar pedestal configuration improved maintenance tasks. The configuration resulted in a wide-open mechanical seal area, which aided in seal inspections and minimized maintenance time.

The spent-chemical pH neutralization system met the stringent requirements of the Chinese agencies for installation in hazardous areas. The system was designed to be economical to operate, and easy to service, and has been doing just that since 2006. PE