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