Membrane Filtra-on Reverse Osmosis and Nanofiltra-on Christopher Bellona Assistant Professor Department of Civil and Environmental Engineering Clarkson University Department of Civil and Environmental Engineering
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Membrane introduc-on and defini-ons Use of RO and NF in metal finishing industry Example of hybrid system Clarkson research group Membrane Types •  Pressure driven membrane processes –  Low-­‐pressure membranes •  Microfiltra-on (MF) and ultrafiltra-on (UF) –  High-­‐pressure membranes •  Reverse osmosis (RO) and nanofiltra-on (NF) •  Current driven membrane processes –  Electrodialysis (ED) and electrodialysis reversal (EDR) Pressure Driven Membranes Low-­‐pressure Membranes High-­‐pressure Membranes RO/NF -­‐ A Few Defini-ons •  Separa-on process: components removed by membrane end up in another process stream Feed Water (QF, CF) Permeate
(QP, CP) Concentrate
(QC, CC) •  Flow rate of permeate produced per flow rate of feed water termed recovery: ! QP $
Recovery = # &
" QF %
•  Efficiency of separa-on called rejec-on: " C %
p
$
Rejection = $1! ''
# Cf &
Reverse Osmosis (RO) •  Dense polymeric membrane material •  Almost always configured into spiral-­‐wound cross-­‐
flow elements •  Can achieve > 99% rejec-on of almost all solutes •  Rela-vely high pressure requirements (200 – 1000 psi) •  Recovery limited by pressure requirements and membrane fouling (usually < 80%) Nanofiltra-on (NF) •  Prepared from variety of materials –  Becoming more robust towards aggressive water matrices and solvents •  Selec-ve rejec-on of divalent ions compared to monovalent ions –  Under certain condi-ons can get nega-ve rejec-on of monovalent ions – ions concentrated in permeate –  Can be used to selec-vely separate components of feed stream by solute size and valence •  Lower pressure requirements than RO (50 – 200 psi) •  Poten-al to operate at higher recovery compared to RO Comparing RO to NF More Energy RO Less Energy NF Applica-on of RO in Metal Finishing Industry •  RO has been proposed or applied in the metal finishing industry to: –  Produce high-­‐quality rinse water –  Reuse rinse water (removal of metals) –  Reuse rinse water and recover metal complexes (Me-­‐
cyanide) for reuse in pla-ng baths •  Issues to be aware of: –  Cannot tolerate solids – need pretreatment (MF or UF) –  Must treat/dispose of concentrate stream if not for reuse –  RO membranes have narrow range of pH tolerance (3 – 9 for long-­‐term opera-on) –  Requires augmen-ng permeate stream with another source of water (amount depends on membrane recovery) Applica-on of NF in Metal Finishing Industry •  NF has been proposed or applied in the metal finishing industry to: –  Produce high-­‐quality rinse water (less effec-ve than RO) –  Separate metals from acids (acids freely permeate NF) for reuse of spent acid solu-ons –  Separate metals from impuri-es (e.g., salts, anions, undesirable metal complexes) •  Issues to be aware of: –  Cannot tolerate solids – need pretreatment (MF or UF) –  Selec-ve separa-ons are difficult to op-mize –  Acidic condi-ons can destroy certain membranes –  Solu-ons may require pre-­‐concentra-on to achieve goals Hybrid System •  Acidic liquor treatment and reuse (Cu2+/H2SO4) •  Incorporates RO and NF to recover water, sulfuric acid and, poten-ally, copper Feed Water High [Cu2+] High [H2SO4] RO-­‐1 RO-­‐1 Perm Very Low [Cu2+] Low [H2SO4] RO-­‐2 RO-­‐2 Conc. Low [Cu2+] Moderate [H2SO4) RO-­‐1 Conc. Very High [Cu2+] Very High [H2SO4) NF-­‐1 NF-­‐1 Perm. Very High [Cu2+] High [H2SO4) NF-­‐1 Perm. Low [Cu2+] Very High [H2SO4) Metal Recovery Water Reuse RO-­‐2 Perm Very Low [Cu2+] Very Low [H2SO4] Treatment/
Disposal (13%) Acid Reuse Clarkson Research Group •  My main research focus has been on municipal wastewater reuse using membrane technology: •  Any membrane applica-on requires op-miza-on: –  Reducing energy consump-on while mee-ng effluent water quality goals –  Preven-ng membrane fouling and deteriora-on –  Maximizing system recovery Clarkson Research Group •  Past and Current Research: –  Modeling and op-mizing membrane separa-ons –  Evalua-ng membrane fouling and filterability –  Tes-ng novel membrane systems •  Capabili-es –  Bench-­‐ and laboratory-­‐scale membrane tes-ng systems –  Wide range of analy-cal capabili-es •  Metal analysis (ICP, AAS) •  Organic analysis (GC-­‐ECD, GC-­‐FID, GC-­‐MS/MS, etc.) •  Surface analysis (SEM microscopy, XRD analysis) Thank You Feel free to contact me: Christopher Bellona [email protected]