reinvent the toilet - fwr the toilet-wheatley-fwr.pdf · reinvent the toilet presented by prof....

Reinvent The Toilet

Presented by Prof. Andrew Wheatley at FWR / CIWEM

John Street, London on Thursday 1st November 2012

Civil and Building Engineering

Familiar Numbers Approaching 50% urbanisation. Worldwide, 2.5 billion people are without a toilet. 1 billion without safe drinking water. Embedded water. Business opportunity is immense.


Gates Criteria

No grids.

Safe.

No Smell, noise , touch.

Easy to use

(developing countries).

Affordable.

Secondary users.


More out of waste

Biorefinery EU

Supergen initiative UK

Supported by the Research Councils

Midlands Universities Sustainable energy consortium Birmingham,Nottingham Loughborough

Sunday, 20 January 2013


Mechanical & Thermal pre-

treatment

AnoxicBioreactor for

Hydrolysis

Anaerobic Bioreactor

Autotrophic Bioreactor

Supercritical Water

Gasification & Partial Oxidation

Heat RecoveryGas Separation &

Purification

Hydrogen

Methane

PhosphateNitrogen

Other Inorganic's

+ Water

Furanic Biofuels

Furanic Di-Carboxyllic

Acids

Mixed Cellulosic Biomass

Recovery of Valuable Minerals

Thermal Hydrolysis

Separation (Filtration &

Ion Exchange)

Sugar-rich Hydrolysate

Residual Cellulose

&Detoxified

Hydrolysate

Catalytic Reactions

Hydrogen

Methane

CO2


Interdisciplinary team

Developing Countries Materials

M Sohail Khan Simon Martin

Chemical Engineering Researchers

Richard Holdich Julia Zakharova

Eric Danso-Boateng

Water Engineering

Andrew Wheatley

Health Ergonomics and Design

Diane Gyi


Thermal Treatment

Hazardous and polluting No infrastructure recovery of valuable materials, sterilised.


Published Energy Values in Wastewater and Sludges

Wastewater Solids

Mj/kg COD MJm3 MJ/kg DS

WERF (2011)

Primary sludge @ 430 mg/L = 13.5 5.8 15.0

Biomass sludge 13.0

Eckhoff and Wood RITC (2011) 4.0

Shizas and Bagley

Toronto (2004)

@ 431 mg/L = 14.7 6.3 3.2

Heodroch,Curtis and Dolfing Newcastle

Industrial

Oven dry @ 718 mg/L = 22.5-28.7

8.3 5.9

Freeze dry @ 576.2 mg/L = 17.7

16.8 10.5

Domestic

Oven dry 5.6 5.1

Freeze dry 17.8 7.6 6.9


Faeces and Primary Sludge Characteristics

Primary sludge, %**

Fats 18 – 26

Fibres 5 – 12

Mineral content 15 – 25

Proteins 15 – 21

Total nitrogen 3.2 – 3.8

Phosphorus 1.4 – 2.5

** Source: Yakovlev and Voronov (2002)

Fats 5 – 25

Fibres 10 – 30

Nitrogenous material 2 – 3

Minerals (K, Ca and P) 5 – 8

Bacterial debris 10 – 30

* Source: Niwagaba et al., 2007

Faeces, % *


Organics in Wastewaters

Mean values, g/L This study (4hrs) Ramke et al. (2009) 12 hrs

Berge et al. 2011

Simulant faeces

Primary sludge

Mixed organics

Food Wastes

COD 33.6 37.6 15 62

TOC 5.53 7.27 10 18

The

Process

Flow Sheet


Why Hydrothermal

Controlled lower temperatures than direct heating.

No drying.

Already wet 5-8% DS

Captured VOC.


Method

Standard synthetic faeces were pressurised to 3 bar, (standard autoclave 1200 C and 1.5 bar)then heated in batch (140°C, 160°C, 180°C and 200°C).

The reaction was then run for different times to collect reaction rate or kinetic data.

Mass loss ratio was measured together with observations on carbonisation.

the first sample was taken as soon as the mixture reached the desired temperature but then run for variable times according to the carbonisation observed.


140°C

Maximum pressure = 7.5bar (Saturated pressure=2.6bar).

None of the experiments carbonised.

Some products became slightly darker.

Product cannot be filtered.

From 2 hours, water could be separated off as clear layers in the collecting vessel.

• Timeline of photos 20mins

50mins 80mins

140mins 260min 380mins


160°C

Maximum pressure = 12bar (Saturated pressure = 5.2bar).

Product carbonised after 6 hours.

Some products became slightly darker.

Carbonised product was easily filterable.

• Timeline of photos 20mins 50mins

80mins 140min

260mins

380mins

320mins


180°C

Maximum pressure = 16bar (Saturated pressure = 9bar).

Product fully carbonised from 2 hours.

Much darker after 30minutes, with black flecks starting to appear (initial stages of carbonisation).

30mins 60mins

90mins 150min

270mins


200°C

Maximum pressure = 20bar (Saturated pressure = 14.5bar).

All products carbonised.

Slightly greater mass loss at longer times.

40mins 70mins

100min 160min

280min


200°C

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0 50 100 150 200 250 300 350

ln(m

/m[0

])

Time (minutes)

Heating time = 50minutes

This experiment had a leak of pressure, but it could be seen that all other points followed the line of best fit well enough that a repeat was not needed

Gradient = 0.0128

1st carbonised point


Summary of experiments to design carbonization conditions

Ln (k)


Water Content

Experiments were run at 180°C with an initial moisture content of 75% instead of 95%.

It was expected for these to carbonise more easily, as the “faeces” particles were a pellet rather than dispersed in the liquid.

Two process times, either side of the carbonisation limit, were tested (30mins, 1hr, 2hr and 4hr).

This had no effect on the product, showing there is no need for mechanical handling before processing

180C for 4 hours

5% ds 25% ds


Citric acid catalyst

A full set of results was collected at 180°C with a citric acid catalyst.

Carbonising after the same amount of time and very similar mass losses.

• 180C for 2 hours With catalyst

No catalyst

• 180C for 1 hour With catalyst

No catalyst


Solids Losses Synthetic

140oC Pressure Cooker

Time min. Mass %

0 0

20 2

50 4

80 6

140 8

260 12

380 15

170oC Superheated

Time min. Mass % 0 0 20 9 30 18 50 22 60 23 80 29 90 38 100 44 150 47 270 52 280 50 380 51


Impact of solid losses on drainage water

20

40

60

80

100

0 100 200 300

Solids , % TOC/10, g/L

Time, min

Primary Sludge

TOC/10, g/L

20

40

60

80

100

0 100 200 300

Solids filt, % TOC/10, g/L

Time, min

Simulant Faeces

TOC/10, g/L

Screened

solids %

Screened

solids %


Ammonia in drainage water

The protein content in sludge is greater

0

200

400

600

800

1000

0 100 200

Ammonia, mg/L

Time, min

Simulantfaeces

Primarysludge


The Laboratory scale Unit

Continuous hydrothermal carbonisation


Conclusions

Reaction time at 160°C would be 6 hours, at 180°C 2 hours.

140°C does not carbonise, even after 12 hours.

It has been shown that no mechanical handling is needed before processing or after.

Fibre and Rheology improved.

The process water contains > 35 g/L COD and > 6 g/L TOC (10-20%)potentially equal amount in the condensate.


Further research

Critical particle size requirements fibres, clogging.

Mass balances heat, solids, nitrogen and VOC.

More valuable by products.

Waste treatment with / without grid connections the biorefinery concept other wastes.

Scale up, real environments and

new materials.


Mechanical & Thermal pre-

treatment

AnoxicBioreactor for

Hydrolysis

Anaerobic Bioreactor

Autotrophic Bioreactor

Supercritical Water

Gasification & Partial Oxidation

Heat RecoveryGas Separation &

Purification

Hydrogen

Methane

PhosphateNitrogen

Other Inorganic's

+ Water

Furanic Biofuels

Furanic Di-Carboxyllic

Acids

Mixed Cellulosic Biomass

Recovery of Valuable Minerals

Thermal Hydrolysis

Separation (Filtration &

Ion Exchange)

Sugar-rich Hydrolysate

Residual Cellulose

&Detoxified

Hydrolysate

Catalytic Reactions

Hydrogen

Methane

CO2


40mins 70mins

100mins 160mins

280mins

Block Diagram for treatment of solids and liquids from Reinvented Toilet

Components

Partial separation Hydrothermal

reactor Decompression Final separation Liquids Salt removal ( as

appropriate)

reinvent the toilet - fwr the toilet-wheatley-fwr.pdf · reinvent the toilet presented by prof....

Documents