Iron, Manganese Removal System Reduces Cooling Tower Cost

In late 2007, AdEdge began working with Maser Consulting Engineers to assist with the design and implementation of an iron and manganese removal system to serve a new water supply for the McGraw-Hill data center in East Windsor, N.J. The site had been purchasing city municipal water to feed its cooling towers but recognized substantial savings in converting to an existing groundwater supply well.

However, the existing well water chemistry presented some challenges with a pH of 5 and elevated iron levels of nearly 5 mg/L. High levels of iron and manganese can reduce cooling tower efficiency and require extensive and costly ongoing maintenance.

AdEdge was selected to design, build and start an integrated treatment system to remove the iron and manganese to meet secondary maximum contaminant levels of 0.3 mg/L and 0.05 mg/L, respectively. AdEdge worked closely with Maser Consulting Engineers and the selected contractor, Central Jersey Mechanical, to supply the treatment system, which included chemical feed (chlorine and pH correction), an AdEdge AD26 packaged iron and manganese removal filtration system, a treated water backwash pump skid, a finished water supply booster pump package and instrumentation. The company also furnished the system with a programmable logic controller (PLC) communications module to interface and allow for continuous monitoring via the data center’s existing SCADA system.

Treatment System

The AdEdge treatment system featured a skid-mounted AD26 oxidation and filtration package in unit size for a maximum design flow rate of 130 gpm. The model AD26-3660CS-S-3-AVH utilizes AdEdge AD26 MnO2 media in a three-vessel carbon steel configuration in parallel. The system is equipped with automated control valves and harness, a central control panel with a PLC and a color user interface screen. System features also include differential pressure switches, a control panel and local gauges, flow sensors, totalizers and a central hydraulic panel with sample ports for a complete functioning packaged unit. A hypochlorite feed and monitoring module and pH adjustment module using sodium hydroxide are also integrated into the system package. Each 36-in.-diameter treatment vessel contains approximately 20 cu ft of AdEdge AD26 oxidation filtration media. Other ancillary equipment integrated with the treatment module includes an auxiliary finished water backwash supply, distribution booster pumps, two 5,000-gal finished water holding tanks and instrumentation. All of these components are integrated into the design and controlled by a single master control panel in the AD26 system.

Performance

The system was started up and commenced operation in July 2008. The system has a very high utilization factor, receiving water nearly 22 hours per day to meet the demand of the cooling towers. Approximately 100 to 110 gpm of water with high iron and manganese levels exceeding 4 mg/L and 0.1 mg/L is being consistently treated to below the treatment goals of 0.3 mg/L and 0.05 mg/L respectively. The system has experienced little or no down time since installation.