Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/792465
Water.desalination+reuse March 2017 View From 33 Impact of Source Water Characteristics and Process Operations on Ceramic Membrane Performance in the Industrial and Municipal Water Segment INTRODUCTION Ceramic ultrafiltra on (CUF) membranes offer advantages over polymeric membranes. Since ceramic membranes (CMs) are more hydrophilic, they are more fouling-tolerant and easier to clean using the same industry-accepted flux maintenance techniques, and hence operate at two to five mes higher flux. CMs are thermally, mechanically, and chemically more robust, and are the membrane of choice for industrial wastewaters. CMs can be integrity tested per standard EPA LT2 methods at higher challenge pressures, and a membrane life of 20 years for municipal applica ons is the norm. Cost-parity between polymeric and ceramic membrane is an explicit goal for Nanostone Water (NSW). CMs were considered more expensive and challenging to manufacture, but improvements in surface area and produc on costs now make them compe ve with polymeric membranes. In the last two years in the U.S., NSW conducted numerous dead-end-mode pilot trials in the municipal, industrial water and wastewater markets to assure performance across a wide range of condi ons. Pilot systems were deployed in field applica ons with varying source-water quali es. Pilot study results confirmed that conven onal flux maintenance techniques are effec ve for ceramic UF membranes operated at moderate flux rates. For feed streams with high suspended solids loading, a minimum stable opera ng flux of 90 gfd (150 lmh) was achieved in dead-end mode, w/o high cross flow or air-scouring. Surface waters with low turbidity achieved a stable opera ng flux at 230 gfd (391 lmh). Hydraulic backwash rates for all cases were operated at 1-3x produc on flux rates, in line with polymeric membrane ultrafiltra on opera on. DIRECT RIVER WATER CASE STUDY (DEAD END FILTRATION) FILTER BACKWASH WASTE RECOVERY (DEAD END FILTRATION) Unit Low Flux Med High Flux gfd (lmh) 115 (195) 184 (313) 230 (391) Coagulant Dose mg/L 1 2 5 Feed Turbidity NTU 3-10 3 3 Permeate Turbidity NTU < 0.08 < 0.08 < 0.08 BW Flux gfd (lmh) 230 (400) 368 (626) 460 (782) Avg Temp o C ( o F) 9 (49) 7 (45) 12 (54) Recovery % 96 95 95 mCIP Frequency days 2-3 2-3 3 Low Flux Low Flux Polymer Challenge Case Study: Direct injec on of 10 mg/L of ca onic and anionic polymer into feed stream of CM module result- ed in high TMP spike, but recov- ered permeability a er rou ne CIP of high/low pH cleaning. Flux and Permeability Recovery: At a feed temperature range of 7-15 o C (45-60 o F), increase flux resulted in expected TMP increase. Flux was not impacted by feed water temperature. Clean water permeability of module was retained a er rou ne CIP even at high flux retained a er rou ne CIP even at high flux condi ons. CATIONIC POLYMER CHALLENGE CATIONIC POLYMER CHALLENGE ANONIC POLYMER CHALLENGE ANONIC POLYMER CHALLENGE ANONIC POLYMER CHALLENGE FILTER BACKWASH WASTE RECOVERY (DEAD END FILTRATION) Site: Conven onal treatment plant with coagula on (alum) and MMF Opera ng Flux: 90 gfd (153 lmh) stable , typical 90% recovery Average TMP: 7 psi (0.4 bar) Feed turbidity: 50-300 NTU, average 100 NTU, spikes > 1000 NTU Permeate turbidity: < 0.1 NTU Challenge: nightly shutdowns, occasional high turbidity feed streams Nightly shutdown CIP INDUSTRIAL COOLING TOWER BLOWDOWN CERTIFICATIONS NSF / ANSI NSF 61 Cer fica on (complete) Materials compa bility NSF / ANSI 419 Cer fica on (In process > 7 LRV Achieved) Cryptosporidium (~ 3m) challenge with direct integrity test correla on Follows EPA Membrane Filtra on Guidance Manual (EPA 815 Third Party Virus, and NSF 372 Verifica on (ongoing) NSF / ANSI 419 Cer fica on (In process > 7 LRV Achieved) m) challenge with direct integrity test correla on Follows EPA Membrane Filtra on Guidance Manual (EPA 815-R-06-009) Third Party Virus, and NSF 372 Verifica on (ongoing) Ini al : 20 min service CEB: 24 hrs CIP: 48 hrs Avg TMP:15 psi (1 bar) Op mized : 20 min service CEB: 24 hrs Avg TMP:5 psi (0.3 bar) Chemical Precipita on + CUF Chemical Precipita on + CUF MgCl 2 + NaOH added upstream in mix tank, followed by primary se ling. Silica: 120 mg/L to < 25 mg/L. Permeate Turbidity < 0.1 NTU, SDI < 3 NSW CM demonstrates high performance versa lity in trea ng high TSS source water. 100 gfd (170 lmh): 20% recycle Medium Flux High Flux Impact of Source Water Characteristics on Ceramic Membrane the Industrial and Municipal INTRODUCTION Ceramic ultrafiltra on (CUF) membranes offer advantages over polymeric membranes. Since ceramic membranes (CMs) are more hydrophilic, they are more fouling-tolerant and easier to clean using the same industry-accepted flux maintenance techniques, and hence operate at two to five mes higher flux. CMs are thermally, mechanically, and chemically more robust, and are the membrane of choice for industrial wastewaters. CMs can be integrity tested per standard EPA LT2 methods at higher challenge pressures, and a membrane life of 20 years for municipal applica ons is the norm. Cost-parity between polymeric and ceramic membrane is an explicit goal for Nanostone Water (NSW). CMs were considered more expensive and challenging to manufacture, but improvements in surface area and produc on costs now make them compe ve with polymeric membranes. In the last two years in the U.S., NSW conducted numerous dead-end-mode pilot trials in the municipal, industrial water and wastewater markets to assure performance across a wide range of condi ons. Pilot systems were deployed in field applica ons with varying source-water quali es. Pilot study results confirmed that conven onal flux maintenance techniques are effec ve for ceramic UF membranes operated at moderate flux rates. For feed streams with high suspended solids loading, a minimum stable opera ng flux of 90 gfd (150 lmh) was achieved in dead-end mode, w/o high cross flow or air-scouring. Surface waters with low turbidity achieved a stable opera ng flux at 230 gfd (391 lmh). Hydraulic backwash rates for all cases were operated at 1-3x produc on flux rates, in line with polymeric membrane ultrafiltra on opera on. DIRECT RIVER WATER CASE STUDY (DEAD END FILTRATION) Unit Low Flux Med High Flux gfd (lmh) 115 (195) 184 (313) 230 (391) Coagulant Dose mg/L 1 2 5 Feed Turbidity NTU 3-10 3 3 Permeate Turbidity NTU < 0.08 < 0.08 < 0.08 BW Flux gfd (lmh) 230 (400) 368 (626) 460 (782) Avg Temp o C ( o F) 9 (49) 7 (45) 12 (54) Recovery % 96 95 95 mCIP Frequency days 2-3 2-3 3 Low Flux Low Medium Flux High Polymer Challenge Case Study: Direct injec on of 10 mg/L of ca onic and anionic polymer into feed stream of CM module result- ed in high TMP spike, but recov- ered permeability a er rou ne CIP of high/low pH cleaning. Flux and Permeability At a feed temperature range increase flux resulted in Flux was not impacted by temperature. Clean water permeability retained a er rou ne CIP condi ons. CATIONIC POLYMER CHALLENGE ANONIC POLYMER INDUSTRIAL COOLING TOWER BLOWDOWN CERTIFICATIONS NSF / ANSI NSF 61 Cer fica on (complete) Materials compa bility NSF / ANSI 419 Cer fica on (In process > 7 LRV Achieved) Cryptosporidium (~ 3m) challenge with direct integrity test correla on Follows EPA Membrane Filtra on Guidance Manual (EPA 815-R-06-009) Third Party Virus, and NSF 372 Verifica on (ongoing) Ini al : 20 min service CEB: 24 hrs CIP: 48 hrs Avg TMP:15 psi (1 bar) Op mized : 20 min service CEB: 24 hrs Avg TMP:5 psi (0.3 bar) Chemical Precipita on + CUF MgCl 2 + NaOH added upstream in mix tank, followed by primary se ling. Silica: 120 mg/L to < 25 mg/L. Permeate Turbidity < 0.1 NTU, SDI < 3 NSW CM demonstrates high performance versa lity in trea ng high TSS source water. 100 gfd (170 lmh): 20% recycle Medium Flux RO COSTS CUT • Water quality concerns led to the introduction of a reverse osmosis (RO) treatment for brackish groundwater at a 10 MGD waste treatment plant under construction in Punta Gorda, Florida • Forecast costs had accordingly escalated from $29 million in 2010 to $42 million in 2014 • Value engineering cut the predicted costs to $37 million • The measures included shrinking the footprint of both the chlorine building and the blending basin • Separate power feeds were provided for the two furthest wells • The capacity of the permeate transfer pumps was reduced • Site redesign shortened the yard piping runs CERAMIC MEMBRANES • Ceramic ultrafi ltration membranes are more fouling- tolerant and easier to clean than polymeric membranes, but are also more expensive • Over the past two years Nanostone Water has conducted numerous pilot trials across a range of sectors and conditions to assure the performance of a new generation of signifi cantly cheaper ceramic membranes • The results of the pilot trials confirmed that conventional flux maintenance techniques are effective for ceramic ultrafiltration membranes running at moderate flux rates WINNER TETRA TECH BEST POSTER AWARD Membrane Technology Conference 2017