Advances in Membrane Technology for Wastewater Recycling

Transcription

1 Water Malaysia 2015 Kuala Lumpur April 2015 Advances in Membrane Technology for Wastewater Recycling 1 Abdul Wahab Mohammad Centre for Sustainable Process Technology (CESPRO) Universiti Kebangsaan Malaysia UKM Bangi, Selangor, MALAYSIA

2 Outline of talk Introduction Membranes: cost effective and proven technology for water reuse and recycling Our own experience on pilot scale study with IWK Other interesting developments in membrane technology Membrane Bioreactor (MBR) and Forward Osmosis, Nanotechnology in membrane developments 2

3 Current challenging issues on water Dwindling water resources Emerging pollutants Endocrine disrupting compounds (EDCs), Pharmaceuticals, Veterinary medicines, Personal care products, nanomaterials Sustainable water management Water resources Energy requirement 3

4 Alternative Water Resources Desalination 4 Water Recyling and Reuse

5 Source: BCC Research In Malaysia, The estimated volume of wastewater generated by municipal and industrial sectors is 2.97 billion cubic meters per year 5

6 Target Opportunities for Water Reuse Key target areas: For basic treatment Agricultural and golf course irrigation Landscape watering Recreational use Toilet flushing Fire suppresion For advanced treatment Potable supplies Reservoir augmentation Groundwater recharge Industrial process 6

7 7

8 Cost of water (in USD) Location $/m3 Adelaide, Australia 3.02 Bangalore India 0.17 Beijing, China 0.54 Jeddah, Saudi Arabia 0.05 London 3.46 New York 2.11 Singapore 3.56 Tolyo 1.96 Manila 0.42 Seoul 2.35 Kuala Lumpur

9 How much we are paying for this? On average RM 1 per 500 ml Or RM 2 per litre Or RM 2000 per m 3 When the cost from tap water is about RM2.5 per m 3. This is a good business 9

10 10 D. Dale, Siemens Water Technology Presentation

11 Pressure-driven membranes Water Molecule MonovalenDivalent t Ions Ions Protein/ Viruses Bacteria Suspended Solids Microfiltration µm Pressure < 2 bar Ultrafiltration 5 20 nm Pressure 1-10 bar Nanofiltration nm Pressure 5-20 bar Reverse OSmosis 11 Nonporous Pressure bar

12 NF vsro NAnofiltration nm Pressure 5-20 bar Reverse Osmosis Nonporous Pressure bar Nanofiltration Porous Membranes, steric and donnan effect Selectivity between ions and small molecules More flexibility in applications Low applied pressure required Reverse Osmosis Non porous, solution diffusion mechanism High rejections for all ions and small molecules High applied pressure required 12

13 Microfiltration, pore sizes 1-2 µm Ultrafiltration, pore sizes 5-20 nm Nanofiltration, pore sizes 1-3 nm Surface imaging using Atomic Force Microscope (AFM) 13

14 INTEGRATED/HYBRID MEMBRANE SYSTEM Integrated/Hybrid Membrane System : Processes where one or more membrane process is coupled with other treatment processes such as coagulation, adsorption, ion exchange and all these processes will be integrated into one system to carry out a specific task*. Common benefits aim to achieve: -Overcome limits of single units -Enhanced quality (safety) of water produced from deleterious water sources (better performance) -Energy savings and environmental benefits -Reduction in capital and operating costs *Fane 1996, Celine et. al

15 CONVENTIONAL WATER TREATMENT PLANT Coagulatio n Sand/Cartridge Filtrations Weaknesses of conventional process: -Unable to treat polluted water resources (pesticides, herbicides, toxins etc.) -Vulnerable towards microorganisms attack -Requires softening process -Unable to remove disinfection by-products (carcinogenic substances)

16 BENEFITS OF INTEGRATED/HYBRID MEMBRANE PROCESS Consistent performance and resistant to fluctuation of raw water quality Able to treat polluted water resources and produce better quality of filtrate Lesser chemical consumption and sludge production Competitive capital and operating costs Reduction in membrane fouling Longer membrane lifespan

17 NEWater The Singapore recycling project Microfiltration/ Ultrafiltration Reverse Osmosis UV Disinfection A source of revenue: High quality ultrapure water for semiconductor manufacturing make-up water for industrial cooling and steam generation Reallocating other water resources for potable consumption 17

18 Findings The report from SINGAPORE WATER RECLAMATION STUDY EXPERT PANEL REVIEW AND FINDINGS (2002) showed that : The physical, chemical and microbiological data for NEWater are well within the latest requirements of the USEPA National Primary and Secondary Drinking Water Standards and WHO Drinking Water Quality Guidelines. Exposure to or consumption of NEWater does not have carcinogenic (cancer causing) effect on the mice and fish, or estrogenic (reproductive or developmental interference) effect on the fish. NEWater is considered safe for potable use, based on the comprehensive physical, chemical and microbiological analysis of NEWater conducted over two years. 18

19 Pilot Plant for Water Recycling, Cyberjaya STP Treated Water 19

20 Parameters Option 1 (PCF-RO) Percent reduction Option 2 (UF-RO) Percent reduction ph BOD 5 (mg/l) % % COD (mg/l) % % TSS (mg/l) % % TDS (mg/l) % % Ammonia % % (mg/l) Nitrate % % (mg/l) Nitrite % % (mg/l) Silica % % (mg/l) Color % % TKN % % Conductivity % % (µs/cm) Total < Generally <0.05 meeting the potable - surfactants water standard! (mg/l) E.coli Odor Alkalinity % 3-15 >63% 20 Turbidity % %

21 Silt Density Index (SDI) Silt density index (SDI) is an analytical method to measure the fouling potential of feed water before entering RO unit. Table 1: Silt density index for points before RO in Phase 2 Points SDI 10-April 17-April 24-April 30-April 8-May 15-May 29-May 5-June Table 2: Indicators for SDI values SDI values Indications SDI < 1 Reverse osmosis system can run for several years without colloidal fouling SDI < 3 Reverse osmosis system can run several months between cleaning SDI 3-5 Particulate fouling is likely to be a problem and frequent, regular cleaning will be needed SDI > 5 Unacceptable, additional pretreatment is needed Comparison of SDI values with other integrated process (Dual-membrane MF/RO process was used in Singapore): (i)suspendedsolidinrawfeedwater- Singapore: 5.8 mg/l Our Pilot plant: mg/l (ii)sdivalues- Singapore: 3.1 Our pilot plant: 3.5-6

22 Membrane Morphology Analysis (a) PCF-RO (b) UF-RO SEM analysis showed that foulant layer of PCF-RO was generally thicker than that of UF-RO system. The thickness of fouling layer: (i) PCF-RO µm (ii) UF-RO µm Sand filtration-uf-ro was more effective in terms of reducing the foulants as compared to coagulation- PCF-RO system. Energy Dispersive X-ray Spectroscopy (EDS) analysis is used for the elemental analysis or chemical characterization of a sample. The percent w/w of foulants composition (Fe): (i) PCF-RO % (ii) UF-RO % Use of FeCl 3 as coagulant might have some influence on the RO membrane fouling.

23 Challenges for municipal water reuse in Malaysia Technology is available, however the main issues are: Acceptance by the public/industry Minimizing the cost of treated water Incentives by the government Feasible concept: Centralized treatment and distribution to industries for indirect reuse 23

24 Reason to be suspicious in wastewater reuse.(you may tick more than one answers) 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Malaysian public perspective on water reuse from sewage Pathogen Toxic substances Long term unknown health effect Doubt with wastewater treatment Cost Water Source Religion Malaysian industries perspective on water reuse from sewage 24

25 25 Other interesting development in membrane technology MBR Forward Osmosis Improvement through nanotechnology

26 Membrane Bioreactor (MBR) Membrane bioreactor (MBR) is the combination of a membrane process like microfiltration or ultrafiltration with a suspended growth bioreactor, and is now widely used for municipal and industrial wastewater treatment with plant sizes up to 80,000 population equivalent (i.e. 48 million liters per day) - Simon Judd (The MBR Book, 2011) 26

27 Drivers for MBR applications Legislation Higher standard for water quality Water scarcity leading to water recycling initiatives Financial considerations (ROI) Increasingly competitive costs of MBR compared to conventional STP Space constraints High population densities and reduced land availability 27

28 Membrane Bioreactors (MBR) MBR OTHER SIGNIFICANT IMPROVEMENTS Improvement in fouling prevention and control New materials rendering improved membrane performance and lower energy requirements Lower capital and operating costs Cost competitive due to market availability 28

29 2 Different MBR Configurations: Side-stream (external) and submerged (internal)

30 Process Scheme of MBRs

31 Membrane Fibers Support Polymeric membrane

32 32 Simon Judd (The MBR Book, 2011)

33 33 Simon Judd (The MBR Book, 2011)

34 34 Simon Judd (The MBR Book, 2011)

35 Forward Osmosis Technology 35 Forward osmosis (FO), is one of the membrane separation technologies in which water migrates across a semi-permeable membrane from a lower osmotic pressure feed solution to a higher osmotic pressure draw solution

36 Schematic diagram of an integrated FO-RO process used for treating anaerobic digester centrate 36 Schematic diagram of the integrated FOMBR or OMBR system for the production of potable water

37 Benefits of FO Operates at very low hydraulic pressures and ambient temperature, which significantly reduce capital costs as a result of the lower energy consumption Low membrane fouling propensity compared to pressure-driven membrane processes, allowing the proper separation and concentration of difficult feed such as waste streams. Water molecules selectively pass through a semi-permeable membrane via osmotic pressure differences into more concentrated streams, thus avoiding membrane fouling and compaction. Loose and lower compaction of the foulant layer on the FO membrane could be easily removed. Studies have shown that the foulant layer formed on the FO membrane surface is considered reversible and could be removed by simple physical cleaning, whereas the densely and higher compaction of the foulant layer formed on the RO membrane may require chemical cleaning methods. Expected FO membrane lifespan is longer compared to the membrane process that utilises hydraulic pressure such as RO. 37

38 ENGINEERED NANOMATERIALS Opportunities for ENM in water treatment and reuse(brame et. al. (2011) Desirable ENM properties Examples of ENM-enabled technologies Large surface area to volume ratio Enhanced catalytic properties Antimicrobial properties Multi-functionality (antibiotic,catalytic, etc.) Self-assembly on surfaces High 38conductivity Superior sorbents with high, irreversible adsorption capacity (e.g., nano-magnetite to remove arsenic and other heavy metals) and reactants (NZVI) Hypercatalysts for advanced oxidation (TiO 2 & fullerene based photocatalysts) & and other priority pollutants Disinfection without harmful byproducts (e.g., enhanced solar and UV disinfection by TiO 2 & derivatized fullerenes) Fouling-resistant (self-cleaning) multi-functional filtration membranes that inactivate virus and destroy organic contaminants Surface structures that decrease bacterial adhesion, biofilm formation and corrosion of water distribution and storage systems Novel electrodes for capacitive deionization (electro-

39 Potential Applications in water industry Membranes Adsorbent Nanocatalyst Pressure-driven membranes novel opportunities to develop more efficient and cost effective nanostructured and reactive membranes for water purification and desalination. Nanoparticles as adsorbent Large surface area functionalized with various chemical groups to increase their affinity towards target compounds water-purification catalysts and redox active media due their large surface areas size and shape dependent optical, electronic and catalytic properties 39

40 Results and discussion Graphene oxide (GO) synthesis Via hummers method Single atomic layer of sp2 carbon atoms Large surface area. Excellent mechanical properties. Excellent antibacterial activity. Average P.S= 20 nm Average P.S= 20 nm

41 Ag- Graphene oxide (GO) Average P.S= 20 nm Average P.S= 20 nm ZnO- Graphene oxide (GO)

42 Psf membranes Psf membranes with GO-silver E-coli growth was inhibited almost completely in Psf-silver-GO membrane 42

43 Final words Various challenges for water industry in the future: resources, emerging pollutants and sustainability Water recycling and reuse is an important alternative water resources Membrane technology, integrated with other methods, as a tool for water treatment, recycle and resource recovery has been demonstrated in many applications MBR and FO are among the membrane technologies with increasing potential applications Advances in nanotechnology may also bring significant improvement in membrane processes. 43

44 Thank You For Listening any questions? 44