Ammonia Bearing Wastewater Treatment for Semiconductor Firm

Challenge

A large semiconductor manufacturing in the Pacific Northwest required an ammonia treatment system to treat approximately 40 gallons per minute of ammonia bearing wastewater.  The design criteria included 24-hours per day operation with a system uptime of 99.5% or greater annually.  The customer also preferred a modular approach in which multiple units would be used at incremental flow rates to treat to a low level of ammonia, both in the aqueous and the gas phase effluents.  The waste stream was anticipated to contain a number of contaminants in addition to ammonia at substantial concentrations.  Siemens Water Technologies was asked to provide a solution to the manufacturer's challenges for this unique waste stream.

Solution

Siemens designed a process which begins with pH adjustment utilizing a single stage pH adjustment system.  This system is capable of maintaining a steady pH with varying flow rates and influent contaminant concentrations.  pH adjustment was critical to maintain all of the NH3 in the free ammonia form.  The pH adjusted water was then treated using multiple skid-mounted dual stage strippers and absorbers.  The entire skid-mounted multistage stripper and absorber was constructed as a single FRP tank with internal walls separating the unit processes.

The sumps are also integral to the stripper/absorber system.  This reduces the overall footprint required by the modules.  Use of the multistage stripper allows for a lower profile system while maintaining stripping efficiency.  The operational aspects of the system allows for utilization of any of the stripper/absorber skids and bringing as many online as needed to match influent flow requirements.  Utilizing the modular approach also allows for system redundancy and very high system availability without the need of an entire offline treatment system.

Results

The modular system has proven itself to exceed the customer's treatment requirements.  Ammonia removal, both in the liquid and gas phase, have exceeded expectations