Transcript Coagulation mechanisms during the substitution of inorganic salts
(Selected) Technology trends within water and waste water treatment
Harsha Ratnaweera Professor in Water & Wastewater Technology Norwegian University of Life Sciences
Outline • Market drivers • Technological sectors – Particle separation (Membranes & sieves) – Biological processes – next generation – Disinfection (Advanced and safer oxidation) – Reuse of water and resources (energy) – Optimal transport (leakage minimisation) – Residuals management – Smart water systems (sensors, software, real-time control)
Market drivers for global water investments (and developments)
Access to safe drinking water Availability Access to safe drinking water
Ratio of wastewater treatment 71 main Indian cities produce 70 million m3 ww/day (132 mill m3/d in 2050), but the treatment capacity is 12 million m3/d…
Global water market
Frost & Sullivan
Drivers and responses • With stricter nutrient standards, –investment for filtration has increased in recent years • With strained water resources globally, –water reuse has increased • increased pressure to move to inherently safer technologies: –Innovative disinfection • New legislations –Increased treatment requirements –Ballast water treatment ($30 billion global market)
Mega trends in water industry: 2020
Technology focus
Frost & Sullivan
Technological developments
Particle separation • From nutrients to colloids • Distribute the loading on unit processes optimally –Fine sieves to remove more particles reducing load on biological & chemical processes –Membrane filtration to remove more and non traditional pollutants cheaper and more efficiently • Reducing the plant footprint, energy – chemical manpower use
Particle removal Fine Sieves: •
40-60% of organic fraction of TSS are from toilet paper tissues
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Majority can be removed with sieves >500 microns.
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Combination of sieves with chemicals Salsnes/Trojan: 50% TSS & 20% BOD removal
Reduction of plant footprints
Reduction of plant footprint BAF – Biological Aerated Filters: Biostyr
1 500 000 PE Biostyr 1 500 000 PE Activated Sludge
Frank Rogalla, Aqualia
Reduction of plant footprint Membrane bio-reactors 1 5
MBBR – Continuous flow intermittent cleaning AS MBBR CFIC
Biowater- CFIC
Reducing footprint of separation stage Actiflow: from 2 hours to 10-20 mins Polymers??
Advances in biological treatment Nitrogen cycle revisited • Short cut in N-removal • No need for external C source • Must prevent NO 2 NO 3 • Slow growing organisms
Advances in biological treatment Anaerobic WWTP revisited • High cost of aeration in Aerobic systems • Historically AN was not popular due to low concentrations in municipal WW, slow growth etc.
• Anaerobic membrane bioreactor (AnMBR): no gravity settling, small footprint and short HRT
Enzymology in Biological WWT • Use of selective enzymes in biological WWT –Can shorten the space requirement by 50% in cold climates –Faster start-up –Less odour –Controlling filamentous microorganisms
Disinfection • Safer, cheaper and more efficient..
UV disinfection • CFD for optimised contact • Medium pressure lamps with quartz coating: >12000 hrs • LED technology: >100 000 hrs (>11 years) • Use of microwaves to energise the UV lamps without electrodes: dramatically improvement in footprint • Better understanding of D10 doses for various microorganisms • Combatting reactivation • Disinfection by-products: no THMs, but more exotic ones?
Reuse of water • Recycled water is becoming to be recognized as a beneficial resource and not a waste lost in the ocean –Policy targets and mandatory reuse –20 to 100% recycling ratio of treated wastewater (California, Cyprus, Florida, Israel, Spain) –satisfy up to 15-35% of water demand (Australia, Singapore)
Membrane technologies • Membrane bioreactors for wastewater treatment –reactor geometry, the hydrodynamics and placement of membrane modules and the overall operating parameters. • membranes for desalination –Pre- treatment methods –CFD to optimize module characteristics (mass transport rates, limited fouling/scaling tendencies, less energy) • Seawater desalination with solar-power
Forward osmosis • Emergency drinks, water in space shuttles, desalination, evaporative cooling water
Nano technology • Nanoadsorbents, magnetic nanoparticles, nanofiltration, nano zero valent iron, nanocatalysts, nanobiocides, nanofibers and mixed technology including catalytic wet air oxidation along with nanoparticles are the products and techniques which are evolved as a result of development in nanotechnology and are being used in wastewater treatment. –Removal of highly toxic matter when present in very low concentrations (membranes doped with TiO2 photocatalysts activated by sunlight
Microfluidics-
removal of toxins • In a microfluidic device, fluids flow through narrow channels at high speeds- the particles flow single file within the channel: possible to select & separate.
• Membrane filtration systems
Phosphorus crisis • Coagulation – reduces the plant availability of phosphorous – After treatment of sludge – Struvite (magnesium ammonium phosphate) production – Reduce Al/Fe use
Residuals management Sludge production and use in agriculture Norway China 100 000t 83% 10 000 000t
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Thermal conversion
– Gasification and pyrolysis (TS of 10-50% instead of 90%) – Supercritical water oxidation (SCWO) process (wet oxidation/ wet combustion): makes sludge highly soluble and homogeneous: small footprints, inert residuals, less sludge & emissions – Steam explosion (Cambi) •
Biogas production
Biofuels from microalgae.
EU FP7 All-gas project
Distribution and transport systems
Real-time surveillance and control • Predictive network modelling and optimisation capabilities to asses the effects of operational or physical changes in system performance and integrity –Real-time network models –Real-time operational optimisation models (anomality detection) Smart IT technologies will become an integral component of modern water networks in the 21 st century • earlier detection • Approximate location from data simulations
Sewer systems
Coping with climate change • More and frequent rains –Overloaded sewers and WWTPs will have even more challenges.
• How to cope with the need?
–Infrastructure expansions –Soft approaches: real time control of sewers and WWTPs (Regnbyge-3M)
Novel sensors and estimation tools • Water quantity- using weather radar and physical measurements • Models to estimate water quality with simpler measurements (flow, etc) • Advanced data processing • Remote surveillance & control • Image analysis • Novel technologies for cheaper and faster detection • Bioindicators
Optimal dosages and images of flocs 100 90 80 70 60 50 40 30 20 10 0,2
Floc features detection limit
0,3 0,4 0,5 0,6 0,7 0,8
Dose, mmole Al/l GLCM
0,9 1 1,1 1,2