EWI Workshop for Technology Roadmaps Dec 07 Technology Roadmap Why Technology Roadmaps Drive and direct targeted R&D areas (directed R&D) Develop R&D capabilities Develop local water technologies First 2 Roadmaps to roll-out: - Bio-processes Technologies (BT) - Chemical & Redox Technologies (CRT) 1
Technology Roadmap Technology Scanning Identify Drivers: Commercial potential Knowledge of market Identified Technologies / Capabilities for Singapore-based entities to develop Academia Inputs Detailed Technology Roadmaps Technology Roadmap - Bioprocess Technologies 2
Why Biological Processes? Most frequently encountered process in large wastewater treatment facility Largest component of a wastewater treatment facility Broad range of applications: Preliminary treatment for water reclamation Energy recovery Opportunities for change: Low energy systems Bioconversion for energy recovery Bio-resource recovery Sludge Minimization Overview of Bioprocess Roadmap Targets: Reduce energy costs Reduce sludge disposal costs Proposed Technologies: Osmotic-Membrane Bioreactors Cyclic MBRs Deflocculated Processes Low Substrate Anaerobic Processes 3
1. Osmotic-Membrane Bioreactors Integration of forward osmosis membrane (FO) separation into activated sludge processes Biomass-effluent separation is achieved by the natural osmosis process Potential Benefits: Reduced energy requirements FO as additional barrier against emerging contaminants, such as POPs, PPCPs etc. FO draw solution used directly for downstream RO process, and can presumably create less operation and maintenance issues for the RO Osmotic-Membrane Bioreactors: Current Status Year 6 Year 5 Year 4 Year 3 Year 2 Year 1 Demonstration plant: - Aeration - Energy balance - Membrane integrity Engineering & piloting: - Reactor design - Membrane module design - O&M protocols Process enhancement: - Biological Nutrient Removal - Effluent Quality - Biomass yield Process Development: - Biomass development - Membrane development Areas of Research: 1. Effect of draw solution investigated by a group in Yale University, and in NUS 2. Osmotic MBR pilot unit is jointly tested by PUB and KIWA using domestic wastewater. Key challenges identified: Membrane material Draw solution 3. Application of FO membrane directly submerged into activated sludge is limited 4
Osmotic-Membrane Bioreactors Research Requirements: 1. FO Membrane Development FO membrane characteristics (e.g. membrane thickness) FO membrane module design 2. Draw Solution Nature of draw solute Post-treatment treatment for separating purified water Recovery of draw solute 3. Process Enhancement Biological nutrient removal Sludge minimization 2. Cyclic MBRs MBRs operated in sequential batch mode Biomass is exposed to cyclic aerobic, anoxic and anaerobic conditions Potential Benefits: Advantages associated with MBRs,, i.e. consistent and low SS effluent quality, high organic loading rate etc. Biological nutrient removal 5
2. Cyclic MBRs: : Current Status Year 6 Year 5 Year 4 Year 3 Demonstration plant: - System integration in water reclamation Engineering & piloting: - Side-stream - Immersed - Aeration Process enhancement: - Biological Nutrient Removal - Effluent Quality - Biomass yield Related Areas: Submerged membranes have been integrated into the aerobic tanks of a multi-stage anaerobic, anoxic and aerobic BNR processes at both pilot and full-scale levels. Year 2 Year 1 Process Development: - Granulation - Bulking Control - Foaming control - Membrane fouling control Areas of Research: A few bench-scale studies of submerged membrane SBRs for BNR have been reported. Cyclic MBRs Research Requirements: 1. Process Development Suspended vs granulated biomass Biological process control Membrane fouling 2. Process Enhancement Biological nutrient removal Nutrient recovery Piloting and Demonstration Requirements: 1. Main treatment vs side-stream stream treatment 2. System integration in water reclamation 6
3. Deflocculated Processes Activated sludge process deliberately operated to maintain biomass in dispersed form, or near bulking conditions. Potential Benefits: Reduced dissolved oxygen requirements Deflocculated Processes: Current Status Year 6 Year 5 Year 4 Year 3 Year 2 Year 1 Demonstration plant - New plant case - Retrofit case Engineering & piloting: - Reactor design - PC&A - O&M protocols - Retrofit protocols Process enhancement: - Biological Nutrient Removal - Effluent Quality - Biomass yield - Process control & automation (PC&A) Process Development: - Filamentous control - DO Control - Liquid-solids disengagement - Sludge dewatering Related Areas: Pilot plant systems deliberately operated to promote near filamentous bulking conditions Related Areas: Studies in deflocculated activated sludge are focused on reflocculation. Little research is aimed at using dispersed flocs. 7
Deflocculated Systems Research Requirements: 1. Process Development Solids-liquid liquid separation Sludge dewatering Biological process control 2. Process Enhancement Effluent quality Process control and automation Biological nutrient removal Piloting and Demonstration Requirements: 1. Reactor Design 2. Process control and automation 3. Retrofitting protocols 4. Low Substrate Anaerobic Processes A possible environmentally sustainable technology for wastewater treatment Novel anaerobic processes that can be applied to the treatment of low-strength wastewaters like domestic wastewater Potential Benefits: Net energy producing process Sludge minimization Achieve biodegradation of organic compounds that are recalcitrant aerobically, e.g. halogenated and phenyl compounds 8
Low Substrate Anaerobic Processes: Current Status Year 6 Year 5 Year 4 Year 3 Year 2 Year 1 Demonstration plant: - Energy balance Engineering & piloting: - Reactor design - O&M protocols Process enhancement: - Effluent Quality - Gas quality & yield Process Development: - Granulation - Biofilm - Cyclic processing Related Areas: Application of UASB for domestic wastewater treatment Related Areas: Integrated anaerobic-aerobic aerobic process for domestic wastewater treatment Areas of Research: Bench-scale studies of anaerobic MBRs for domestic wastewater treatment. Low Substrate Anaerobic Processes Research Requirements: 1. Process Development Suspended vs granulated vs biofilms Biological process control 2. Process Enhancement Effluent quality Gas quality and yield Piloting and Demonstration Requirements: 1. Reactor design 2. Energy balance 9
Cyclic MBR Targets: Energy and Sludge minimization -Reduce energy costs -Reduce sludge management costs THANK YOU Contact person: Pang Chee Meng pang_chee_meng@pub.gov.sg 10
Technology Roadmap Chemical Redox Why Chemical Redox Technologies? Potential in water & wastewater, air, wastes (sludge, soil) Increasing numbers of emerging and trace contaminants Ability to degrade recalcitrant/non-biodegradable contaminants. Actively researched opportunity for knowledge transfer Potentially many emerging technologies in this category Benefits to adjacent clusters: electronics (UPW), chemicals, photovoltaic clean energy, pharmaceutical 11
Overview of Chemical Redox Roadmap Targets: Improve water quality Improve treatment efficiency Treatment technique for specific waste stream Reduce chemical usage in treatment processes Reduce residues Proposed Technologies 1. TiO 2 Photocatalytic Oxidation (PCO) 2. Silver Disinfection 3. Sulfate Radicals Advanced Oxidation Process 1. TiO 2 Photocatalytic Oxidation (PCO) Production of oxidative hydroxyl radicals in the presence of TiO 2 and energy of light, UV < 380nm. Potential Benefits: Possibility of simultaneous disinfection, oxidative and reductive reactions Complete mineralization of recalcitrant/non-biodegradable organics: CO 2 and water Minimal/no waste disposal problem Oxidation of pollutants at low/trace level (ppb) Draw on solar technology to reduce operating cost 12
TiO 2 Photocatalytic Oxidation: Current Status Limited industrial wastewater treatment applications: 1. SOLARDETOX - Solar/TiO 2 /Fe (pesticides) PUB Pilot testing (engineering prospect ) - Reduction in membrane fouling with the use of TiO 2 Active area of research - Modifications of TiO 2 - Effectiveness of TiO 2 oxidation on emerging organic compounds - Solar Incorporation TiO 2 Photocatalytic Oxidation (PCO) Research Requirements: 1. Improve quantum efficiency, solar incorporation 2 Reduction of mass transfer resistances in immobilized system 3. Hybrid system 1 + 1 + 1 H 2 O 2, O 3, ultrasound, biological processes, membrane 4. Inconsistency in complex effluent compositions, possibility of higher toxicity intermediates 5. Opportunity of PCO in enhancement of municipal wastewater treatment?? 13
2. Silver Disinfection Silver is known for its disinfection properties, originating from the use of copper-silver ionization (CSI) Powerful effects against bacteria / virus Potential Benefits: Minimize production of disinfection-by by- products: THMs,, chloroform etc Silver ions possess residual disinfection effect Silver Disinfection: Current Status Commercial water treatment applications: - Nanoparticles SilverSol TM (cooling water system, algaecide) - Nanosilver activated carbon filter small scale residential usage 14
Silver Disinfection Research Requirements 1. Process Development Effectiveness on emerging pathogens Applicability in drinking water production?? Disinfection control and optimization 2. Process Enhancement - Synergistic effect of combined technologies 3. Piloting and Demonstration Requirements: - System design - Operation & maintenance issues 3. Sulphate radicals (SR) Sulphate radicals ( SO 4 ) possess high oxidation power, equivalent to hydroxyl radicals More stable than hydroxyl radicals Emerging water treatment technology Oxidation Power, V Fluorine Sulphate Radical Hydroxyl Radical Oxidants Ozone Hydrogen Peroxide Chlorine 3.0 2.5-3.1 2.8 2.1 1.8 1.4 2.8 15
Sulphate Radicals (SRs( SRs): Current Status Methods to produce SRs 1. Direct UV irradiation of peroxymonosulphate or monopersulphate 2. Coupling of peroxymonosulphate and monopersulphate with transition metal (cobalt, silver, iron) Sulphate Radicals (SRs( SRs) Research Requirements: - Understanding of SR-AOP oxidation mechanisms - Investigate ways to catalyze formation of SRs - Explore its applicability in water treatment domain - Solar enhancement??? - Disinfection properties??? 16
THANK YOU Contact person: Jodie Chin Jodie_CHIN@pub.gov.sg 17