« What future for Membrane Processes in Water and Wastewater
Transcription
« What future for Membrane Processes in Water and Wastewater
Symposium sur l ’Eau ParisParis- Berlin: 23 octobre 2003 « What future for Membrane Processes in Water and Wastewater Treatment ? » Hervé BUISSON, Director, Anjou Recherche, Maisons-Laffitte R&D Centre, France ANJOU RECHERCHE PLAN 1 Introduction 2 Present context and challenges 3 Current Developments 4 Conclusions ANJOU RECHERCHE | From microfiltration to reverse osmosis SCANNING ELECTRON MICROSCOPE IONS OPTICAL MICROSCOPE VISIBLE TO NAKED EYE MACRO MOLECULESMICRO PARTICLES MOLECULES MACRO PARTICLES MICRON Angström Molecular weight Sugars Viruses Algae and protozoans Dissolved salts Bacteria Pesticides Colloids Metal ions Sands Humic acids REVERSE OSMOSIS MICROFILTRATION NANOFILTRATION ULTRAFILTRATION CONVENTIONAL FILTRATION Note : 1 Angström = 10-10 meter = 10 -4 micron | Current Drinking Water Applications Disinfection (crypto, giardia) Disinfection + Pesticides Clarification Polishing NOM, BCOD, pesticides, softening) X Reverse Osmosis X Nanofiltration Microfiltration Ultrafiltration Desalination X X (UF alone for virus) (PAC hybrid) X X X Hybride Processes (PAC, coagulants) | Current Wastewater Applications Tertiary treatment (for reuse) Reverse Osmosis Enhanced Secondary (reuse or sensitive areas) X Nanofiltration Microfiltration Ultrafiltration (as pre-treatment) MBR X Industrial In-Plant Industrial Process Water X X X X X (UF more eg for O&G) X Hybride Processes (PAC, coagulants) X X X Other Industrial Wastewater Hybrid (MEUF, MEXT) ED X ED/CDI PLAN 1 Introduction 2 Present context and challenges 3 Current Developments 4 Conclusions ANJOU RECHERCHE | Brief History of Membrane Technology for Water Applications... 1956 - early 1980s : RO desalination, no commercial MF/UF for drinking water mid-1980 - early 1990s :Developement of Memcor (MF), Aquasource (UF), clean waters & small capacities (1993 - Milwaukee- cryptosporidium crisis) mid-1990 - 2002: Start of market growth, new competitors (Zenon, Xflow,Hydranautics, Pall, Ionics) with second generation membranes/modules) Use on not so clean waters Start of immersed MBR products Now Large plants > 200000m3/jour Strong growth of RO desalination market | Early worldwide capacity increase Cumulative capacities (MLD) MF/UF/NF Worldwide Installed Capacities 1600 1400 1200 1000 800 MF+UF NF/OI 600 Total 400 200 0 1991 1992 1993 1994 1995 1996 1997 1998 1999 | Technico-Economical Hurdless to Membrane Success... • Membrane costs vs membrane life uncertainty • Flux Decline (fouling, scaling,blocking,) • Need for proper process integration • Operation and maintenance issues | UN PROBLEME CLEF: la non maitrise du risque de colmatage 0,60 1,80 1,40 0,40 1,20 1,00 0,30 0,80 0,20 0,10 0,60 0,40 absorbance UV 254nm de l'eau filtrée à traiter 0,20 0,00 01/06/99 02/06/99 ANJOU RECHERCHE 03/06/99 04/06/99 05/06/99 06/06/99 0,00 07/06/99 Indice UV 254 nm (abs/m) Perméabilité relative Lp/Lp0 1,60 0,50 PLAN 1 Introduction 2 Present context and challenges 3 Current Developments 4 Conclusions ANJOU RECHERCHE | From Good Membranes to Succesful Operations Hydraulique hydraulique Procédé conditions d'opération Réalisation stratégie de lavage Intégration/couplage pré-- traitement pré Fibres Creuses (i-- e, e(i e- i) Spiralé Plan Module ORGANIQUES Polysulfone , PVDF,... Membrane INORGANIQUES Oxydes Al ou Zr Zeolites,... Zeolites ,... Ingénierie Exploitation Consignes et procédures d ’exploitation Gestion des « variabilités» et des risques | Going back to basics: Hydraulics Process scale Pipe scale Membrane scale Fibre scale | Going back to basics: Water Chemistry Étude de 2 configurations d ’un pilote CMF-S TOC 175 150 Alimentation 14 Perméat 12 Rétrolavage 10 8 Configuration purge à l ’égout 6 125 4 100 35 Prélévement analyses 40 45 50 55 60 65 70 75 time (min) 75 16 50 25 0 20/8/02 25/8/02 30/8/02 4/9/02 9/9/02 14/9/02 19/9/02 24/9/02 29/9/02 4/10/02 9/10/02 alimentation 14 Configuration recirculation permeat 12 TOC -1 - 2 Perméabilité à 20°C (L.h .m .bar-1) Polysaccharides 16 10 8 6 4 PS associé aux pertes de performance PS éliminé lors du nettoyage 35 40 45 50 55 time (min) 60 65 70 75 | Going back to basics: Surface chemistry ? MEB avant / après Extraction du dépôt sur une membrane plane Avant extraction A Après extraction B C A: Membrane colmatée - B: Membrane après sonication C: Membrane après sonication et raclage | Building upon standard processes knowhow 1. P-removal with MBR technology 2. Trace organics removal in MBR “Development of optimised & cost effective advanced P removal strategies using immersed membranes” “Contribution of membrane processes to the removal of refractory COD and health related organic pollutants from water cycles” Combination of 3 processes are considered: • Development of Bio-P in MBR • Comparison with Co-P alone, or Co-P + Bio- P • Evaluation of P-adsorption in MBR effluent on activated media Focus on: • Endocrine disrupting compounds (EDCs) • Pharmaceuticals (PhACs) Configuration 1: Pre-denitrification Configuration 2: Post- denitrification => post-DN for advanced N-removal in MBR In view of water reuse (Berlin: short water cycle) Ruhleben WWTP | IMF2: removal of micro-polluants in Biosep Pre-DN MBR Post-DN MBR Elimination rate 0% Polar compounds : PhACs - Non biodegradable - carbamacépine - Partly biodegradable - phenazone 50% 100% Adsorbtion not improved for polar compounds - propyphenazone -AAA Better biodegradation favoured by high SRT Pre-DN > Post-DN? -FAA Not (less) polar compounds : EDCs - Non biodegradable - bisphenol-A - Partly biodegradable Adsorption improved for non-polar compounds - estrone Improvement of steroids removal - estradiol - ethynilestradiol PhACs and EDCs analysed 2-6 times per month since Nov. 2001 on mean 24-h samples taken « in switch » (with plants HRT) statistical analyses possible (6 à 12 bi-monthly values) | Focussing on global solutions rather than membranes Pre -Treatment lime CMF-S coagulant Ozone & BAC Filtration Raw Water Storage ozone 8 8 CO 2 chlorine ammonia lime Bendigo Consumers Post Treatment & Storage Waste Residuals | Key to sucess: Operating expertise and know-how Exploitation conditions d ’exploitation Outils d’aide à la conduite gestion des « variabilités » | KEY OPERATING LESSONS • Adequate training and operating procedures are essential (key possible failures, cleaning, recommended first actions) • Need for operator-support tools to help develop a continuous diagnostic of the hydraulics/behaviour of the plant and anticipate problems ASAP (smart but robust interface between supervision and operators) • Access to strong chemical/biochemical analytical backup possible fouling/cleaning diagnostic (some applications are tough, with negative ROIs!) • Integration of Membrane operations into global water and waste operating scheme (sludge disposal, pre-treatment, pollution prevention plans as well as possible process water segregation) PLAN 1 Introduction 2 Present context and challenges 3 Current Developments 4 Conclusions ANJOU RECHERCHE | CONCLUSIONS: ? Membranes and Membrane Processes are not Magical!! Their implementation at very large scale still represents an unacceptable level of technico-economical risk today for some applications. ? The challenge : Find the right place for these tools into our toolbox, develop the right process trains for each application, develop robust adapted operating practices, minimizing technical anf financial risks ? Membranes need to be forgotten, or seen as only part of the solution for membrane processes to gain full potential in Water and Wastewater Treatment ANJOU RECHERCHE