ELECTRODIALYTIC VALORISATION OF SEWAGE SLUDGE AND ITS ASHES - - PowerPoint PPT Presentation

ELECTRODIALYTIC VALORISATION OF SEWAGE SLUDGE AND ITS ASHES – POTENTIAL OF PHOSPHORUS RECOVERY

• P. GUEDES1,2, N. COUTO1,2, E. MATEUS2, L.M. OTTOSEN2, ALEXANDRA B. RIBEIRO1

1CENSE, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e

Tecnologia, Universidade Nova de Lisboa, 2829‐516 Caparica, Portugal.

2Department of Civil Engineering, Technical University of Denmark, DK‐2800, Lyngby, Denmark

CYPRUS 2016 - 4th International Conference on Sustainable Solid Waste Management, Limassol, 23–25 June 2016

PROBLEMATIC

Phosphorus (P) is a macronutrient indispensable for plant growth. EU is almost entirely dependent upon imports, from China, Jordan, Morocco, South Africa and USA controlling 85% of global phosphate reserves1.

1Smit, A.L., et al., 2009, Plant Research International B.V., Wageningen, Report 282.

Image credits: Jen Christiansen (map and graphs); Source: U.S. Geological Survey, Mineral Commodity Summaries, January 2009.

WASTEWATER TREATMENT PLANTS

destroys organic contaminants, pathogens while promoting mass reduction

Incineration P bioavailable

Sewage sludge 90‐95% P

Organic contaminants Heavy metals

Sewage Sludge Ash rich in P Heavy metals Dioxins P not bioavailable

TECHNOLOGY

Anode (eq.) 2H2O ‐ 4e‐ → O2 + 4H+ Cathode (eq.) 2H2O + 2e‐ → H2 + 2OH‐

Aims to remove contaminants (e.g. heavy metals) from fine porous matrices under the influence of an applied low level direct current

ELECTRODIALYTIC PROCESS

Patent PCT/DK95/00209

AIM

sewage sludge sewage sludge ashes

P-recovery 1 2 Electrodialytic process (ED)

Contaminants removal

SEWAGE SLUDGE ASHES

HEAVY METALS & PHOSPHORUS

‐ Guedes P, Couto N, Ottosen LM, Kirkelund GM, Mateus EP, Ribeiro AB (2016) Valorization of ferric sewage sludge ashes: potential as a phosphorus source, Waste Management, 52, pp. 193‐201, DOI: 10.1016/j.wasman.2016.03.040 ‐ Guedes P, Couto N, Ottosen LM, Ribeiro AB (2014), Phosphorus recovery from sewage sludge ash through an electrodialytic process, Waste Management, 34(5), pp. 886‐892, DOI: 10.1016/j.wasman.2014.02.021

Denmark, Lynetten incinerator, Copenhagen :

• fresh SSA ‐ immediately after the incineration process
• deposited SSA ‐ from the deposit

SSA SAMPLING

SSA DIFFERENCES

Fresh vs Deposited Statistical differences (p<0.05)

• pH; Conductivity; Water content; Loss on ignition; Solubility in water
• Elements Concentration: Al, Zn, Cu (attributed to SSA heterogeneity)

Fresh ash Deposited ash

Matrix compartment: anode Matrix compartment: central Acid suspension H2SO4 + stirrer Electrolyte: closed system Ion exchange membranes

2C‐cell

3C‐cell

ED CELLS

EXPERIMENTAL DESIGN

Constants:

• Current (50 mA)

Variables:

• SSA (fresh, deposited)
• Cell set‐up (3C, 2C‐cell)
• Acid concentration H2SO4 (0.08, 0.19 M)

N.º exp.

• 12 (n=1)

0.08 M 0.19 M Lowest (%) Examples (%) Lowest (%) Examples (%) cell SSA Fe/Pb Cd Cu Zn Fe/Pb: Cd Cu Zn 3C fresh 6/2 70 69 62 9/14 82 69 56 deposited 6/2 64 40 69 12/10 82 76 73 2C fresh 10/7 18 55 64 6/12 23 69 53 deposited 12/9 23 44 51 8/14 27 64 51

• Removal → Time dependent
• Best approach → 3C‐cell, H2SO4 0.19 M
• SSA did no influence the results

% of HM removal (7 days)

HM REMOVAL

0.08 M 0.19 M cell SSA % P solubilized % P recovered % P solubilized % P recovered 3C fresh 76 18 91 25 deposited 72 19 92 29 2C fresh 91 77 99 93 deposited 67 56 99 97

• Higher acid concentration → higher P solubilization
• 2C‐cell + 0.19M H2SO4 → highest P recovery (anolyte, 93 – 97%)
• SSA influenced the results → 2C‐cell + 0.08M H2SO4

P RECOVERY

SEWAGE SLUDGE

EMERGING ORGANIC CONTAMINANTS & PHOSPHORUS

‐ Guedes P*, Magro C, Couto N, Mosca A, Mateus EP, Ribeiro AB (2015) Potential of the electrodialytic process for emerging

• rganic contaminants remediation and phosphorus separation from sewage sludge, Electrochimica Acta, 181, pp. 109‐117,

DOI: 10.1016/j.electacta.2015.03.167 ‐ Guedes P, Mateus EP, Almeida J, Ferreira AR, Couto N, Ribeiro AB (submitted) Electrodialytic treatment of fresh sewage sludge: Current intensity influence on phosphorus recovery and organic contaminants removal ‐ Guedes P, Rodrigues A, Almeida J, Couto N, Mateus EP, Ribeiro AB (under preparation) Electrodialytic treatment of sewage sludge: Influence on microbiological community

• Portugal, WWTP Quinta do Conde (Águas de Lisboa e Vale do Tejo), Sesimbra
• SS from the secondary settling tank

SEWAGE SLUDGE SAMPLING

2C‐cell

Study: Phosphorus 6 OCs

• Caffeine (Caf)
• Bisphenol A (BPA)
• 17β‐oestradiol (E2)
• 17α‐ethinyloestradiol (EE2)
• Ibuprofen (Ibu)
• Oxybenzone (MBPh)

Frozen SS

Constants:

• pH: < 2
• Time: 5 days

Variables:

• 3 cell set‐ups
• Current (mA)
• 0, 20, 50

N.º exp.

• 7 (n=2)

Fresh SS

Constants:

• Cell set‐up (best)
• pH: no adjustment
• Time: 3 days

Variables:

• SS
• Current (mA)
• 0, 50, 75, 100
• Current steps

Microbiological control N.º exp.

• 6 (n=2)

+ 2 control electrodegradation (25 mA, 6 h, n=2)

EXPERIMENTAL DESIGN

 Highest P‐recovery → 78% (anolyte)  Best OCs degradation → 71‐97% (Caf‐Ibu) Cell set‐up:

• Matrix compartment: SS + stirrer
• Electrolyte: closed system
• Ion exchange membranes

 Current influenced P‐recovery

MAIN RESULTS: FROZEN SS

MAIN RESULTS: FRESH SS

• % P recovered → current intensity
• Current steps did not improve P recovery
• Highest recovery → 70% → 100 mA

55% → 24 h

• OCs degradation improved with current
• Higher: 50 mA & 100‐75‐50 mA

10 20 30 40 50 60 70 80 Control Exp-1 Exp-2 Exp-3

%P electrolyte r2= 0.989

50 75 100 I (mA)

CONCLUSIONS

ED

SS SSA

P → 2C‐cell (anode+CEM, H2SO4 0.19M) HM → 3C‐cell (H2SO4 0.19M) P+OCs → 2C‐cell (cathode+AEM,100 mA)

BEST CELL DESIGN

P

SS SSA

125 g of P/kg (97%, 7d) 40 g of P/ kg (70%, 3d)

P RECOVERY

ACKNOWLEDGMENTS

Lynettefællesskabet (Lynetten incinerator)