How can Polymeric or Ceramic Membranes be Evaluated to Replace Granular Media Filters at an Existing Surface Water Treatment Plant

Session WED06 How can Polymeric or Ceramic Membranes be evaluated to replace Granular Media Filters at an existing Surface Water Treatment Plant Pei-Shin Wu, PE & Mike Condran, PE, March 6, 2024, 11: AM Peace River Manasota Regional Water Supply Authority Serves drinking water to 1 million residents Four member counties & one City customer Charlotte DeSoto Manatee Sarasota North Port Operates Peace River Facility Peace River Facility Constituents of Concern with seasonal variability Turbidity T&O Color TOC Seasonality in peaking (March – August) Regional growth driving expansion Identified MGD more capacity needed by 2030 Evaluate alternative technologies Future regulatory requirements Operational flexibility Minimize footprint and cost Phased construction GAC STORAGE INCLINE AND D DISTRIBUTI MEMBRA PLATE ON NES SETTLER S Membrane Pilot Objectives Verify both membrane technologies can Compare polymeric to ceramic membrane meet Authority WQ goals and regulatory performance standards Evaluate impacts of PAC and polymer on Compare membranes’ water quality to membranes Plant granular media filters Identify operating/design parameters Membrane Design Criteria Properties Polymeric Ceramic Phase Phase Phase Phase Membrane Material Polyvinylidene fluoride (PVDF) hollow fiber Silicon carbide (SiC) flat plate Pore Size 0.02 µm 0.1 µm Flow Path Outside-in Outside-in Flux (gfd) 28 – 32 32 – 35 100 – 150 200 – Recovery (%) 95 95 95 Backwash Every 42 minutes, with air scour Every 30-60 minutes, with air scour and spray wash Cleaning Maintenance Clean: Chemical Enhanced Backwash: 5 days/week 250 mg/LNaOCl 1 – 3 times/day 250 – 1000 mg/L 2 days/week 500 mg/L Citric Acid Maintenance Clean: Recovery Clean: Every 1-3 months, soaking in higher Every 1 month with extended soak strength chemical Integrity Test 1/day 1/week 1/day Turbidity Performance Cont’d Both membranes showed capability to handle large swings in feed water quality. Color Performance GMF showed lower color levels than both membranes, but average color removal was similar. Other Water Quality Similar to GMF, both membranes Alkalinity and hardness remained saw minimal TOC and T&O removal. consistent from settled water (membrane feed) to permeate for both membranes. In Phase 1, both membranes were highly affected by PAC and algae carryover. Operational Challenges Pilot-scale limitations: less automation, reduced alarms, more prone to human errors. Foaming caused by incorrect chemical addition during cleaning cycle at polymeric membrane unit Upstream alum dosing increases dissolved Al in membrane feed Similar red stain seen at Plant finished water chlorine analyzers.