anaerobic digestion of lipids - wordpress.com · anaerobic digestion of lipids:! the development of...

Anaerobic Digestion of Lipids:!the development of a multifaceted solution!

B. Conall Holohan!

Focusing on AD solution to dairy wastewater lipids

- !Microbial Communities

and !Reactors!

Wastewater Treatment!Anaerobic Digestion!

!

-  Energy neutral/positive!-  No by-products (sludge)!-  Small land area needed!-  Enclosed (no-odours)!

Efficient !Can become an income provider.!

Activated Sludge !!!

•  Energy expensive!•  Large volume of sludge produced !•  Large space needed!•  Odour producing!!

Inefficient!Current practice!

Figure: Cheung et al. (2013)!

Dairy Industry!

•  Ending of the EU quotas!o  Predictions 2020: 50% increase in production.!

•  High level complex wastewater produced.!

•  Outdated WW treatment systems.!

Lipids in Dairy WW!•  Lipids are removed - dissolved air flotation (DAF)!

•  Causes foaming in activated sludge treatment!

•  ‘Treatment’: Removed & landspread with the sludge from aerobic treatment.!

•  Wasted resource: Energy possibility is high!

Figure: Bioscience Inc. (2012)!

Biogas Potential from Lipids!

Carbohydrate!

Lipid!

Protein!

Biogas (l/g)! Methane (%)!

0.830!

69.5!1.125!

50.0!

68.8!0.921!

Amended from Alves et al. (2009).

AD of Lipids!Challenging!

•  Inhibition & Accumulation!•  Floatation of granules!•  Difficulty in degradation!

•  Current practice:!•  Non-treatment/separation!•  Long treatment time (weeks)!

Lipids!

LCFAs!

VFAs!

Methane!

Aim of Reactor Trial: !Identify the optimum anaerobic

reactor design.!& investigate the effect(s) of Trace Element addition!

3 Reactors !R1 - UASB! R2 - UASB-Filter! R3 - EGSB!

Trial Conditions!

•  Wastewater: “Raw” - Post-screening/Pre-DAF Treatment!

•  Sludge: Granular - Carbery Co. Cork!

•  Began @ 72hr HRT & 1.4 OLR!

0.00!

10.00!

20.00!

30.00!

40.00!

50.00!

60.00!

70.00!

80.00!

90.00!

100.00!

110.00!

0! 6! 12! 18! 24! 30! 36! 42! 48! 54! 60!

% C

OD

Rem

oval!

Time (Days)!

UASB!UASB-Anaerobic Filter!EGSB!

>70% Total COD Removal!

Trac

e El

emen

t Add

ition

!

>70% Soluble COD Removal!

0.00!

10.00!

20.00!

30.00!

40.00!

50.00!

60.00!

70.00!

80.00!

90.00!

100.00!

0! 6! 12! 18! 24! 30! 36! 42! 48! 54! 60!

% C

OD

Rem

oval!

Time (Days)!

UASB!UASB-Anaerobic Filter!EGSB!Tr

ace

Elem

ent A

dditi

on!

Poor Lipid Removal!

-20!

0!

20!

40!

60!

80!

100!

10! 15! 20! 25! 30! 35! 40! 45! 50! 55! 60!

Time (Days)!

R1!UASB!UASB-Anaerobic Filter!

Addition of TE = Lipid Removal!

TE Addition!

Biogas Production!Pre TE Addition!

•  Consistent > 60 % Methane concentration!

•  Biogas conversion efficiency: ~50%!

Post TE Addition!

•  Consistently >60% Methane concentration!

•  Volume of biogas increased significantly!

•  Biogas conversion efficiency: >70%!

Trace Element Effect..!

•  Shown preliminarily by Karlsson et al (2012)!

•  Addition of Fe; Co; Ni increased the methane yield!

•  Oleic Acid: 59% +/- 5% Increase!

Further TE tests!•  Degradation Tests!

•  Oleate (LCFA: C18)!•  Skimmed Milk Powder (SMP) !

•  Aims: !1.  Replicate results seen in reactor trial!2.  Compare various TE compleations: !o  Shelton & Tiedje (1984) !o  Banks et al. (2012)!

0.0!

13.3!

26.7!

40.0!

53.3!

66.7!

80.0!

0! 2! 4! 6! 8! 10! 12! 14! 16! 18!Time (hours)!

Blank!ST!Banks!

Increase in SMP Degradation Rate with TEs!

Increase in Oleate Degradation Rate with TEs!

0.0!

15.0!

30.0!

45.0!

60.0!

0! 2! 4! 6! 8! 10! 12! 14!Time (hours)!

Banks!ST!Blank!

Ultra-Sonication (US)!

•  Increases surface area (2.3X)!

•  Cracks/Craters formed!

•  Permeability increases 37%!

Figure: Cho et al., Bioresource Technology, (2013).!

Positive Effect of US!30.3% ! 9.4%!

35.4%! 2.3%!

Increases in biogas production when US applied.!

Following 16 days!% Increase in CH4 production!

•  Glucose: 70.4 %!

•  SMP: 59.4 %!

•  Oleate: 53.6 % !

Conclusions!

!!

Reactor Design can have an important positive effect.!!

T.E.s have a positive effect on the degradation of lipids. !!

Ultrasonication has a positive effect on the degradation of Oleate. !!!

With thanks to… !

•  Supervisor: Prof. Vincent O’Flaherty!

•  Dr. Dermot Hughes !

•  Dr. Si-Kyung Cho!

•  Dr. Florence Abram!

Nicholas Hogan!&!

Stephen Moloney!