Coagulation mechanisms during the substitution of inorganic salts

Report
(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 nontraditional pollutants cheaper and more efficiently
• Reducing the plant footprint, energy – chemicalmanpower use
Particle removal
Fine Sieves:
• 40-60% of organic fraction of TSS are from toilet paper
tissues
• Majority can be removed with sieves >500 microns.
• 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
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 Csource
• Must prevent NO2NO3
• 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
10 000 000t
83%
• 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 21st 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
Floc features
detection limit
GLCM
90
Tot. P efficiency, %
80
70
60
50
40
30
20
10
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Dose, mmole Al/l
0.9
1
1.1
1.2
A period of many changes
with lot of room for new
developments
Paradigm shift

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