Wastewater - source of bioenergy and clean water: The All-Gas and Incover dem...
Harnessing Oxygen_v6a RR210314
1. Harnessing Oxygen to BoostHarnessing Oxygen to Boost
Performance in WastewaterPerformance in Wastewater
Treatment PlantsTreatment Plants
Richard Randle - WaterApplications Sales Engineer, BOCRichard Randle - WaterApplications Sales Engineer, BOC
2. 03/31/16 Fußzeile Page 2
Criteria forBOOSTING PERFORMANCE
Boosting performanceBoosting performance
Control VOC generation and odour
We can achieveachieve these without necessarily
increasing size of bioreactor or plant footprint
mprove final effluent quality and consent compliance
Increase COD load handling capability
Option to recycle
=
3. 03/31/16 Fußzeile Page 3
Why do we need to boost
performance?
Time
1. Diurnal variationCOD (mg/l)
7,500
2,500
Load limitLoad limit
4. 03/31/16 Fußzeile Page 4
Why do we need to boost performance?
2. Handle heavierload
COD NH4-N
11. 03/31/16 Fußzeile Page 11
O2 content – pure oxygen versus air
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Pure oxygen Air
Relative oxygen concentrations
Nitrogen & others
Oxygen
12. 03/31/16 Fußzeile Page 12
Ratio of off-gas using pure oxygen versus air
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Pure oxygen Air
Relative levels of oxygen dissolved
by applying 1m3 of gas in a pure oxygen injection system
Off gas
Oxygen
dissolved
Off-gasOff-gas
13. 03/31/16 Fußzeile Page 13
Off-gas comparison with air-based activated sludge
plant
1. Retains heat – increase rate biological performance
2. Less foam; no antifoam requirement
3. Reduced VOCs/ odour emission
Benefits of less off-gas?
14. 03/31/16 Fußzeile Page 14
Vitox pure oxygen activated sludge process
Gas Control Panel
Control Panel
VITOX
Venturi
Land Based
Pump
Sparge
Bar Injection Nozzle
Dissolved
Oxygen Probe
Oxygen Pipework
15. 03/31/16 Fußzeile Page 15
Solvox dissolvers
•8 grids installed – 1 perlane
•Temporary overload during capital works
•Only use oxygen during overload
•Zero powerrequirement
16. 03/31/16 Fußzeile Page 16
Power used
kg O2 dissolved/ kW
kg O2 dissolved/ kW
kg O2 dissolved/ kW
Vitox
Solvox
3 to 4.5
Device Range
Fine bubble diffuser 1 to 2
Oxygen TransferEfficiencies (OTEs)
∞
18. 03/31/16 Fußzeile Page 18
1. Food Processing
● G’s (vegetable) - 1.2 tpd COD load, doubled organic load capability to 2.4 tpd vitox. pH
control on blowers
● Bernard Mathews – installed vitox to handle seasonal peak loads
2. Animal Rendering
● Prosper de Mulder (Saria) – upgraded over 20years ago
……All upgraded air-based systems
3. Papermills - newsprint
● Aylesford (11 tpd)
● UPM Kymmene (24 tpd)
………..both used purpose built pure oxygen ASPs – KSPs are warm effluent, river discharge.
Both proven by pilot plant trials to confirm design and performance. Both use PSAs –
attractive economics compared to aeration
Examples of systems using pure oxygen
19. 03/31/16 Fußzeile Page 19
4. Oil refinery effluent (complex organic wastes)
● Ineos, Grangemouth
● ConocoPhillips, Grimsby
● Shell Godorf oil refinery, Germany
5. Pharmachemwaste streams (>1000ppm)
● Ineos Nitriles, Seal Sands
● Shasun Pharmaceuticals (originally Sterling Organics) Or, Cramlington – gone to air based
● Warner Lambert, Co. Cork – upgraded from air based system
● Sword Labs, Dublin
● Flexys (originally Monsanto), Ruabon.
● Bristol Myers (closed)
6. Coking plant effluent (isocyanates, thiosulphates, phenolics) – see ‘coke oven effluent’
TATA (Scunthorpe; Port Talbot)
Monkton Coke Hargreaves
Coalite (closed)
Examples of systems using pure oxygen cont.
20. 03/31/16 Fußzeile Page 20
Acknowledgements
● Understanding the Alpha Factor (Malcolm E. Fabiyi - March 2008)
● Aeration and the role of oxygen (Arthur Boon, 1989)
● The use of Oxygen in Activated Sludge treatment of Wastewater (Jeff
Halsall circa 2005)
richard.randle@boc.com
Editor's Notes
The message
At no time will I tell you to throw away all aerators in existence. Unfortunately not been able to change the laws of physics in pure oxygen’s favour However what I can convey today is a message to say that when looking to biologically remove BOD aerobically, pure oxygen may not just be an alternative to air but can do things that simply air cannot do under certain circumstances!
What do we mean by ‘boosting performance’…….?
Improve final effluent quality and consent compliance – treat to quality that reduces conveyance charges through Mogden formula. Extension to this is treating to quality level that allows river discharge
Self explanatory - Increased load due to process changes or production rise.
Environmental concerns, especially in built-up or residential areas. Volatiles and unpleasant odours driven off by the volume of off-gas
Where final effluent water is of a quality that can be treated further for reuse
…..By considering pure oxygen, we can achieve all these without …….
Plant has been designed to a specification based on hydraulic and organic load. Since then, load variation has changed. Problem now presents itself in terms of treating the spikes….
Production has increased or raw material has changed…..
Equipment within the ASP, whether a tank or surface aerator for example, may need either repair or replacement.
Tighter restrictions on final effluent quality, places pressure on site to enhance current system…
What are the alternatives?? -
Plant has been designed according hydraulic and organic load. Normally build in some contingency…..
However, peaks appear either randomly or systematically. Either way, there is increased pressure on plant to meet consent. This affects costs as well as risking compliance. Due to the rate of transfer from gas into the mixed liquor , pure oxygen is the ONLY means of satisfying these peaks.
[Can go into Henry’s law but believe this should be left outside this arena and happy to go through afterwards]
This has a knock on effect down stream of the bioreactor, with poor settlement due to sludge bulking.
Also need to be conscious of the fact that there is a limit to the amount of air that can be injected into the reactor…4.8kg O2 etc
……….=> next slide
……..By dealing with the peaks, capacity is essentially increased.
Depending on the technology involved, alpha factor, depth of tank etc, OTE into mixed liqour of an ASP can vary between 75 and 99%. Example shows 90% TE, 10% of which will be present as an off gas. This is in stark contrast to an air based system that can transfer only 3%
With a 5 m tank, approximately 30 times less gaseous volume passing through ASP for a given OT
Land based vitox - Automated system, pressurised side stream dissolver, using venturi. Talk about its operation briefly, using DO signal etc and fact that THE NOZZLES POINTING DOWNWARDS. ALSO REM THAT THE BENDS ARE DELIBERATELY SQUARE AND NOT SMOOTH TO INCREASE TURBULENCE and bubble size
Solvox –short description – EDPM rubber hose with minute ports for fine bubbles, arranged on a mat designed to suit shape of tank base
Put into context the different devices and relative OTE in terms of power consumption…..talk around fact that Solvox does not require power
Also state these are Realistic efficiencies and not the ones claimed by manufacturers at zero DO in clean water
Previous slides focused solely on the use of pure oxygen and its harnessing thereof in a bioreactor. The relevance of the above slide - a shot of our containerised demonstration plant - considers the ASP as a whole. “I.E this means there is also a solution for organically overloaded bioreactors and hydraulically overloaded clarifiers by”.. Adopting oxy-MBR technology, it takes into account oxygen transfer and solid liquid separation in one device, incorporating cross flow membrane separation with vitox technology. Air is also used for CO2 removal for pH control and membrane scouring.
So we can convert and effectively at least double the capacity of an overloaded ASP without excessive increase in footprint.
