Project Synopsis

Provide process engineering and control design support for a plant trial of a wedge-wire filter used in the treatment of process wastewater and stormwater as a potential replacement of an existing Lamella Gravity Settler.

Project Summary

The client, a large inorganic chemical manufacturer, requested that Process Engineering Associates, LLC (PROCESS) provide process and control design support for an extended trial of a wedge-wire filter used in the treatment of process wastewater and stormwater.  The trial is a technology evaluation, the results of which will be used to establish the feasibility of replacing an existing Lamella Gravity Settler with a wedge-wire filter bank.  The existing Lamella Gravity Settler has reached the end of its useful life and must be replaced.  However, the replacement cost is considerably higher than other filter technologies and the site requires a technical evaluation of other filtration technologies to determine the correct course of action.  Specifically, the capability of the wedge-wire filter to meet the existing outfall permit requirements needs to be determined.

PROCESS provided the process design layout per redline revisions to the P&IDs, mechanical design via piping isometrics based on the P&ID revisions, and control design via a DCS Control Narrative that incorporated the relevant instrumentation.  The overall design package included the physical layout of the trial filter with piping, valving, and controls.  The trial filter is a vendor-supplied package with an automated purge valve.  The mechanical design provided direct-feed and bypass piping to the trial filter.  The control logic allows for the DCS to automatically put the trial filter on-line and to take it off-line based on the level profile of the feed sump.  The control configuration prioritizes on-stream time of the trial filter to maximize the process data generated which will be analyzed as part of the client’s Lamella Gravity Settler replacement evaluation.  Additional timer-driven control logic cycles the solids purge valve integral to the filter package only when the filter is on-line.  Finally, an advanced control scheme was employed that used the filter feed controller to determine if the filter system was plugged and automatically bypassed the filter while notifying operations of the issue.

The outfall analyses are on-going as the overall trial is expected to occur over ~6 months in duration to ensure adequate data volume collected to justify an environmental permit revision.  (The Lamella is a permitted environmental control device so the site wastewater permit will have to be modified if the Lamella is not replaced in-kind.)  Initial testing results have shown the outfall clarity from the wedge-wire trial filter exceeds the existing permit requirements for solids removal.

The client plans to develop a larger capital project to install a bank of wedge-wire filters provided the preliminary results to-date are indicative of the technology’s capability in the filtration of the site’s wastewater.  The project will include the necessary fixed and rotating equipment, automation and controls, and any infrastructure needed.

Industry Type

Chemical Manufacturing


Utilized Skills

  • Plant trial design and management
  • Industrial wastewater treatment process design
  • Process controls design.

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