Dr Bill Barber 10th November 2015
The future of biosolids, Where will the next 20 years take us
20th European Biosolids & Organic Resources Conference
The Past
J. W. Slater, F. E. S., 1888
Sewage Treatment, Purification and Utilization. A practical manual for the use of
• corporations, • local boards, • medical officers of health, • inspectors of nuisances, • chemists, • manufacturers, • riparian owners, • engineers and • ratepayers
Br352-8-18-7
-1+1+5
79.904
S162-8-18-7
-2+24
32.066
6
eaking
ludge
clay, sawdust moistened with sulphuric acid, turpentine, alcohol, iron filings, brick dust, oil tar, coal, hydrochloric acid gas, tanners’s spent bark, animal charcoal, salt, sugar, urine, carbolic acid, chloroform, phosphoric acid, “soft-sludge” from alum works, blood, metallic salts, salicylic acid, milk of magnesia, fibriferous mud, nitro-muriate of tin, spongy iron, petroleum
clay, sawdust moistened with sulphuric acid, turpentine, alcohol, iron filings, brick dust, oil tar, coal, hydrochloric acid gas, tanners’s spent bark, animal charcoal, salt, sugar, urine, carbolic acid, chloroform, phosphoric acid, “soft-sludge” from alum works, blood, metallic salts, salicylic acid, milk of magnesia, fibriferous mud, nitro-muriate of tin, spongy iron, petroleum
1846 1854 1857 1858 1859 1863 1867
Liming Activated carbon
Filter press dewatering
Primary settlement, electricity
Thermal drying
Freezing
1871
Ammonium recovery by
steam stripping
1872
Screening and straining to allow use of sludge
water for irrigation
1872
Advanced thermal drying with heat
recovery
1880s
Interest in fermentative putrefaction
(anaerobic digestion)
1887
Anaerobic sand filter
1890
Agricultural products
from sludge
1895
Exeter (septic)
tank
1902
Staged anaerobic digestion
1906
Theory of AD for biogas
prediction
1909
Imhoff tank
Wet air oxidation of
sludge
1935
Microwave pretreatment
for AD
1965
Thermal hydrolysis of
ligno-cellulosic material
1969
Anaerobicfilter
1970s
Acid phase AD also with pre-treatment
(ultrasound)
Late 1970s
Upflow Anaerobic Sludge Blanket
1980
Anaerobic fluidized bed
1990s
Anaerobic membrane bioreactor
1914
Activated sludge
Struvite Precipitation
1916
The Wastewater treatment plant of today
ScreeningPrimary
SettlementActivated
SludgeNutrient
Recovery
ThickeningPre
-treatmentAnaerobicDigestion
Energy Recovery
DewateringBiosolids
to land
Final effluent
1872 1858 1914 1857
1955 1976 1895 18601857
1820s 1900
19th century
Pre- 1920
Post- 1920
Key
The future of sewage sludge treatment
Present Drivers
1804
1927
1960
1974
1987
1999
2012
+123
+33
+14
+13
+12
+13
Population Growth
Higher population which is more affluent
…with greater affluence
…and changing tastes…
0
10
20
30
40
50
60
70
80
90
100
World Africa Asia Europe LatinAmerica
NorthAmerica
Pe
rce
nta
ge
1950 2007 2030 (predicted)
Increasing urbanisation
Climate change
Security
of supply
Environmental impact of intermittent discharges
Environmental and regulatory threat from pollution incidents
Water quality
Increasing flood risk
Indirect, socio-economic risks
Future sludge production
Global sludge production
www.worldmapper.org
Global sludge production
www.worldmapper.org
Global sludge production
www.worldmapper.org
South America
Africa
Asia
Oceana
North America
Europe
Prediction of future sludge production
2015
2020
2030
20402050
> 45% dry solids50 – 60% dry solids
Changing sludge type
Future Direction
Water Energy Nutrients
Resource Recovery
Water
Resource Recovery
Texasdroughtproject.org
Water shortage and drought
“A growing world population, unrelenting
urbanization, increasing scarcity of good
quality water resources and rising fertilizer
prices are the driving forces behind the
accelerating upward trend in the use of
wastewater, excreta and greywater for
agriculture and aquaculture..”
Irrigation Water
Clean water Untreated wastewater
Energy
Resource Recovery
Basis: 10,000 TDSA
Energy recovery from primary sludge
Basis: 10,000 TDSA
Energy recovery from secondary sludge
28% 15%
Energy recovery from sludge
Why has anaerobic digestion not progressed?
– Energy production was
not the primary driver
– Conservative industry led
by meeting regulatory
requirements
– Text book rule of thumb
based on previous
conservative designs
WEF, cited in M&E 4th Edn.Rideal, 1906
4C8H13N2O3 + 14H2O = 4N2 + 19CH4 + 13CO2 + 2H2
Anaerobic Digestion
Modern Anaerobic Digestion
http://www.boldride.com/ride/1912/ford-model-t-touring#gallery/3
Modern Anaerobic Digestion with pre-treatment
Dewatering
More Biogas
The “Black Box”
The irony of anaerobic digestion pre-treatment
To increase biogas production,energy efficiency
And coincidentally also
kills disease causing organisms
+
i.e. pre-treatment by itself can meet the original drivers for having anaerobic digestion in the first place making it
redundant
Enhancing anaerobic digestion – series operation
59% VSR
66% VSR
59%
59% 18%
71% VSR59% 18% 13%
In Practice – Tacoma Central, USA
57% VSR
67% VSR
57%
57% 23%
In Practice – Budd Inlet, USA
Standard Practice today – anaerobic digestion
Series digestion variant
Apparatus for the (anaerobic) treatment of sewage. Extracted from U.S. Patent No. 699,345. (May, 1902)
Series digestion variant
Co-digestion (of primary and secondary sludge)
Extremely high loading rates makes digestion plants significantly smaller
There is much we can do with existing digestion, also…..
- More and better data collection• Empirical modelling
- pH control• Addition of buffers
• Addition of other materials
• CO2 stripping
- Nutrient addition• Directly
• Addition of other materials
- Toxicity control• In situ or side-stream stripping
• Alternative configurations (with recycle)
- Kinetic control• Better suited for different configurations
• Engine tuning on Model T Ford?𝝁 = 𝝁𝒎𝒂𝒙
𝑺
𝑲𝒔+𝑺
Nutrients
Resource Recovery
Ammonia
Energy N2
“Nitrification under Aërobic conditions”
Welcome to Manchester…………
Energy N2 N2
Am
monia
Am
monia
Energy
Activated Sludge Haber Bosch
Nitrogen, an energy intensive closed loop
Staged Anaerobic Fluidized
Membrane Bioreactor
- Inf. COD 300 ±60 mg/l
- Temperature of 8°C
- Effluent <25 mg/l BOD
- Outperformed ASP for
numerous xenobiotics
- Produces clean nutrient
rich water
High Rate Anaerobic Treatment to replace Activated Sludge?
Recovery of phosphorus?
Adapted from Cordell et al., 2009. The story of phosphorus: Global food security and food for thought
Angola
Biosolids use as a fertilizer
A very low energy and low carbon footprint fertilizer providing nitrogen, phosphorous, micro- and macro-nutrients whilst also providing moisture, carbon and drought resistance
“The Bazalgette process, as applied to London, is a total failure. It involves the utter waste of all the manurial matters in
the sewage....”
J. W. Slater, F. E. S., 1888
Biosolids dewatering
Skinner, Samuel J., et al. "Quantification of wastewater sludge dewatering." Water research (2015).
- The biggest factor limiting
dewaterability is the sludge itself
• Pre-dewatering technology
- Better understanding of dewatering
mechanisms
• Better predictions
- Improved upstream anaerobic
digestion
• Enhanced dewatering
- Tighter wastewater regulations
• Worse dewatering
Our plants are designed to meet 19th
century drivers
However, there is much to be
learnt by looking back
Sludge production will increase and
change in composition and location
Modern drivers are placing
more emphasis on water,
energy and nutrients
A lot can be done to improve
energy efficiency
through AD We may need to rethink
wastewater treatment at a fundamental
level
Conclusions
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