Dean Herron, Aqua Enviro

1. AVENUES OF FINANCE –
ASSET VALUE
#UKADBiogas @adbioresources
CHAIR:
DR ROBIN SZMIDT, TARGET RENEWABLES
PANEL:
DAN POULSON, BASEPOWER
DEAN HERRON, AQUA ENVIRO
PHIL GERRARD, EASTERN COUNTIES FINANCE

2. www.aquaenviro.co.uk
Dewaterability Testing
Developing a Comprehensive Method for
Assessing the Ultimate Dewaterability of Sludges
Dean Herron

3. www.aquaenviro.co.uk
Understanding the challenges of
dewatering Food Waste Digestate
• 2008 Climate Change Act
• Renewable Energy Incentives (ROC’s/FIT/RHI)
• 2009-2014 over 120 Digesters built in the UK
• Financial models often omit Digestate Disposal
• Can be as much as gate fee

4. www.aquaenviro.co.uk
Understanding the challenges of
dewatering Food Waste Digestate
• Variable feed stocks (dependant upon commercially available
source material) mean that a solution is often plug and play
• Variable Digester characteristics, (HRT, VS destruction) mean
that digestate from each site will dewater differently
Dewater on site
Dewatering from 95% water to 75%
water provides 5 fold reductions in
volumes for transport & disposal
Liquors are created on
site which require
treatment

5. www.aquaenviro.co.uk
Understanding the challenges of
dewatering Food Waste Digestate
Liquor Treatment
• Aerobic treatment processes can produce a good quality
effluent but the liquors must be fully characterised to
produce effective designs
• Effluents can be further polished to produce excellent high
quality product water if needed
Liquor treatment and digestate disposal costs must be
incorporated into future economic models

6. www.aquaenviro.co.uk
Dewatering Optimisation Test
Cake Quality (DS%)
Filtrate Quality (mg/l)
Resistance to Filtration (m/kgDS)
PLR Feed DS%
Pre-treatment (TH)
Storage Times
Specific Imports
Dewatering
Technology
Pre conditioning

7. www.aquaenviro.co.uk
Pressure Gauge
Pressure Line
Outer Liquid
Collection Tube
Inner Filter
Membrane
Filtrate
Collection
Weighing Scales
Pressure and
Filtrate Mass
Logging Device
Compressor

8. www.aquaenviro.co.uk
Method Development Testing

9. www.aquaenviro.co.uk
Method Development Testing
Run Number Total Filtrate Prodn Filtrate TSS Product DS
g mg/l DS%
1 355.24 458 22.39
2 349.54 462 22.46
3 340.78 452 22.35
4 359.31 323 23.52
5 353.84 491.4 21.5
6 357.96 456.7 22.28
7 351.23 453.3 22.51
Standard
Deviation 6 54 0.6

10. www.aquaenviro.co.uk
Further Method Development
Testing
Site Data DOT Data
Polymer solution Strength (%) 0.35 0.4 0.4 0.4
Feed solids (%) 2.46 2.46 2.46 2.46
Polymer flow (l/hr) 7600 n/a n/a n/a
Sludge flow 37.6 m³/h 400ml 400ml 400ml
Polymer Load Rate (kg/tDS) 28.7 15 25 30
Product DS (%) 26.96 22.63 24.47 26.27
Filtrate SS (mg/l) 310 531 479 420

11. www.aquaenviro.co.uk
Further Method Development
Testing
• Different feed sludge types
• Different polymer types (and other conditioning
agents)
• Deriving operating conditions to match on-site
dewatering processes
• Combine with Zhan Wellens testing of liquors
Full Economic model for the feasibility of dewatering any
given sludge

12. www.aquaenviro.co.uk
Questions?

13. AVENUES OF FINANCE –
ASSET VALUE
#UKADBiogas @adbioresources
CHAIR:
DR ROBIN SZMIDT, TARGET RENEWABLES
PANEL:
DAN POULSON, BASEPOWER
DEAN HERRON, AQUA ENVIRO
PHIL GERRARD, EASTERN COUNTIES FINANCE