Transition towards efficient “used water ‘ treatment

Willy Verstraete

Lab Microbial Ecology and Technology

LabMET - Ghent University

Overview

• 1.The energy facts from the water industry

• 2. Incremental appraoches

• 3.Mavericks in the old line of used water treatment

• 4. The real step forward : closing the water cycle entirely – the “used water factory” and development of the pull side

• 5.Conclusions

World Cities exceeding 5 million residents

The energy facts from the water industry

• The water industry consumes about 1% of the overall electricity (Caldwell 2009; 3e

Eur Water and Wastewater Conf )

• The energy costs are increasing and rise to some 20% of those of the water company

• Activatated sludge is the Major energy consumer

World Cities exceeding 5 million residents

The energy facts from the water industry

• Good STP housekeeping can help a lot ; up to 40% saving is possible ( Caldwell 2009)

• Yet , overall the nagging problem is that STPs simply dissipate ‘used water ‘ , rather than re-use the resources it contains – STP do waste resources

• In this way , it is the indirect contribution to climate change of the STPs , -and not their energy use as such -, which is the key challenge .

The overall facts from the water industry

• Heat recovery at the house / underground thermal energy storage (Frijns et al. 2013; Energy Conv Mang. 65: 357-363)

• FOG / Fryer oil : use as biodiesel on the STP

• Sieve out the cellulose : up to 40% less sludge production ; payback 7 yrs (Ruiken et al .2013; Water Res. 47: 43-48)

• Microbial fuel cells and BioElectrochemical Systems : thus far only at mL or L scale ( Arends &Verstraete 2012;Microbial Biotech 5: 333-346)

Incremental appraoches :5 examples

Bio Electrochemical Systems (BES)

• Conventional thinking

– ‘Gratuit’ energy from wastewater

BES from wastewater 0.1 kWelm-3

Benchmarks:

Batteries 30-90 kWelm-3

Chemical fuel cells 140 kWelm-3

Anaerobic digestion 4 kWelm-3

Take home: Plenty of energy-dense competitor systems exist ;added value must be sought outside the ‘energy’ aspect of BES

Conventional thinking :

-‘Gratuit’ products from wastewatersuch as caustic, peroxide,ammonia, organic

acids & alcoholsYet

• Extra energy must be supplied to the anodic harvested electrons

• Biological current is the limiting factor !

• Conventional production lines must be faced

Take home: Production is about-Rates (>100 kg m-3 d-1)

-Quality (specification is essential)-Quantities ( 10 000 tonnes per year to start)

Incremental approaches :example 5: Improved digestion

*Sludge pretreatment such as

-Thermal Pressure Hydrolysis

-Sonication

-Milling (Halalsheh et al. 2011;Biores Technol 102:748-752)

-Peroxide treatment of digestate :up to 13% more energy and 11% less residual solids ; net economic benefit of about some 1 USD per Inh per yr (Lozano 2010 ; WEFTEC Session 61-76: 4885-4897 )

Incremental approaches :Improved digestion

Mavericks in the ‘old’ line of sewage treatment

• 1.Nereda

• 2.Demon

• 3.Integration of renewable energy

• 4.Operating as ‘energy buffer ‘

• 5.Upgrading to green gas

• 6. Struvite recovery

Mavericks in the ‘old’ line 1.Nereda

Take home : 20% lower construction costs ; 30% less energy consumption but no recovery

Mavericks in the ‘old’ line :2. Demon (Wett 2007; Wat Sci Tech 56:81-86)

Macao (Egypt): sewage treatment plant

INESS® Integrated New Energy Solutions & Services wastewater treatment plant powered by the sun

Wind turbine

Anaerobic digester

Photovoltaic roof

Towards minimal external power consumption

Mavericks in the ‘old line’ : 3. Addition of renewable energy / Retrofitting of CAS-design

Mavericks in the ‘old’ line :4. Energy buffer

• During rush hours of electricity use by the public , stop the aeration of STW : up to 1% on the overall consumption

- Can be of economic signifcance but may provoke plenty of process adjustment

• During valley hours , use the electricity to to produce by electrolysis H2 and enrich the biogas :

The Electrochea concept

Green energy Electrolysis

Hydrogenotrophic Methanogens

CO2 rich gas

Green gas (100% CH4)

Mavericks in the ‘old’ line :5. Upgrading to green gas

Mavericks in the ‘old’ line :6. Struvite recovery

• Various industrial processes : (Cornel & Schaum 2009:Water Sci Techn 59: 1069-1076)

-The Pearl Ostara process

-The Nuresys process

THE POINT OF INTEREST : THE QUALITY AND THE QUANTITIES OF THE MAP PRODUCED

THE REAL STEP FORWARD :The old and the new water cycle

OLD NEWNatural system

Purification

Transport

USER

Transport

Dissipative treatment

Natural system

Natural system

Purification

Transport

Natural system

USER

Transport & centralized re-use

Localre-use

The water cycle

A. Decentralized

* 20% of the world population struggles with a

‘sanitation taboo ‘

* Education to re-use the resources present in

wastewater is key for progress in this domain

Note: Deep down in our crocodile brain , we all are

abhored by fecal matter and hence the reuse of

materials which have been in contact with it

(The Bill Gates foundation )

(Vlaeminck et al. 2007; Appl. Microbiol. Biotechnol. 74: 1376-1384; LabMET)

The water cycle

MgCl2

N2 gas

Plant growth products

Biogas kWh

Stabilized solids

Struvite

UASB Septic Tank

Sorption

To surface water

Black water

Decantor

OLAND

A. Decentralized: Autonomic treatment

Case study (Sneek, Netherland): Pioneer project of 32 houses with vacuum toilets (flushing with 1L in stead of 7L)

net energy production of 5 kWhel IE-1 year -1

The water cycle

(Zeeman et al. 2008; Water Sci. & Techn. 57, 1207-1212)

A. Decentralized: Autonomic treatment of black water

Discharge

OLAND Struvite

precipitatio

nB

iogas

recovery

Reuse

Grey water

Sewer

Rain and pretreated sewage can be used to :

- have green rooftops

- produce algae biomass

The water cycleA. Decentralized: Green roofs for grey water & sewage

treatment

(Zamolla et al. 2013; Bioresource Technol 130:152-160; LabMET)

27

A-stage I-stage

Take home: (i) Biofilm allowed bacterial attachment(ii) The interaction between algae and bacteria is an important mechanism in this system. (Zamalloa et al. 2012; Biores Techn 130: 152-160 , LabMET )

Take home: (i) Biofilm allowed bacterial attachment(ii) The interaction between algae and bacteria is an important mechanism in this system. (Zamalloa et al. 2012; Biores Techn 130: 152-160 , LabMET )

Lab-scale set-up

Overall performanceParameter

Raw sewage

EffluentRemoval

efficiency (%)EU discharge limits (mg/L)

COD (mg/L) 143 ±49 36 ±±±±8 73 ±12 125

Ntotal (mg/L) 41±9 14 ±±±±7 66 ±12 15

TAN (mg/L) 33 ±9 1.9 ±±±±1.9 94 ±6 -

NO3-N (mg/L) 0.2 ±0.8 9.3 ±±±±6.9 - -

NO2-N (mg/L) 0.5 ±1.2 0.7 ±±±±0.5 - -

Ptotal (mg/L) 5 ±2 0.2 ±±±±0.1 96 ±4 2

pH 7.8 ±0.3 7.5 ±±±±0.6 - 6.5-9.5

Take home: COD and Ptotal meet EU discharge limits. But Ntotal needs to be lowered still with some 25%.

Take home: COD and Ptotal meet EU discharge limits. But Ntotal needs to be lowered still with some 25%.

29

Preliminary cost assessment

Capital cost €/m3sewage treated

A-stage; CSTR 9

A-stage; Settler + thickener 38

I-stage; PBR 150

A/I-stage; instrumentation 78

Total capital cost 313

Annualized cost (€/m3.year) 84

(€/m3.day) 0.23

Operational costs €/m3

Electricity 0.001

Flocculant 0.02

Total cost (€/m3) 0.25Take home: Considering a factor 2 for practical upscaling,

a projected value can be around 0.5 €/m3

Take home: Considering a factor 2 for practical upscaling,

a projected value can be around 0.5 €/m3

Mass balance

I-stage∼66 kgCOD/I.E. year∼5 kgN/I.E. year∼0.7 kgP/I.E. year

Domestic sewage

Treated water

∼18 kgCOD/I.E. year∼1.7 kgN/I.E. year∼0.03 kgP/I.E. year

A-stage

Organic sludge∼40 kgCOD/I.E. year∼0.5 kgN/I.E. year∼0.5 kgP/I.E. year

Flocculant

6-12 kgFeSO4/I.E. year

Algal sludge

∼31 kgCOD/I.E. year∼1.9 kgN/I.E. year∼0.16 kgP/I.E. year

∼ 0.9 kgN/I.E. year∼ 0.01 kgP/I.E. year

Loss

Fit for bio-refinery

Fit for re-use

B. Centralized: Conventional activated sludge (CAS) design

� Capex + Opex: 17 - 40 EUR IE-1 year-1

� Energy use: 20-35 kWhel IE−1 year−1

� Energy recovery via sludge digestion is limited

◊ Theor.: 30-40 kWh IE-1 year-1

◊ Pract.: 15-20 kWh IE-1 year-1

� N, P, K � no recovery

� All organic C via biology + sludge incineration to CO2

� Water � hardly re-used

Take home: The centralized wastewater treatment must be

redesigned entirely!

The water cycle

Food wastes must be properly re-used

• Food consumes 15% of the US overall energy budget

• About 20% of food is wasted, i.e. 2-3% of

the total energy budget (Webber & Cuellar, 2010; EST; DOI 10:1021)

New Urban Metabolism

Take home:

• Co-digestion can recover a major part of this energy

• Food and kitchen wastes can be a driver of a new type of

wastewater treatment

Resources

Production IE−1 year−1

Market price

Value (EUR IE−1 year−1)

SewageKitchen

wasteSewage

Sewage +

Kitchen waste

Potable water 54 m3 1.2 EUR m−3 65.4 65.4

Heat recovered (5°cooling)

• Electricity consumption

• Heat recovered

-179 kWhel

496 kWhth

0.10 EUR kWhel−1

0.05 EUR kWhth−1

6.9 6.9

Anaerobic digestion

• Electricity produced

• Heat generated

23 kWhel

24 kWhth

16 kWhel

17 kWhth

0.10 EUR kWhel−1

0.05 EUR kWhth−1

3.5 5.9

Biochar production 5.7 kg 3.9 kg 0.14 EUR kg−1 0.8 1.3

Recovered nitrogen 2.4 kg 0.2 kg 1.15 EUR kg−1 N 2.7 2.9

Recovered phosphorus 0.82 kg 0.66 kg 1.35 EUR kg−1 P 1.1 2.0

Overall 80.4 84.5

Sewage as a resource

(Verstraete & Vlaeminck, 2010; Keynote Paper 2nd Xiamen International Forum on Urban Environment; LabMET)

CAPEX + OPEX = 0.46 €/m³ RO permeate

0.33 €/m³ influent(Van Houtte and Verbauwhede 2008;

Desalination 218, 198-207)

Discharge in the sea0.060 €/m³ RO concentrate

0.017 €/m³ influent

Benefit = reusable water1.20 €/m³ RO permeate

0.86 €/m³ influent

CAS1 m³ 0.90 m³ 0.72 m³

0.10 m³ 0.18 m³

UF

(R = 90%)

RO

(R = 80%)

Sewage as a resource of water

Balance (m³ influent): - 0.600 for CAS- 0.330 for UF/RO polishing- 0.017 for concentrate discharge+ 0.860 for water valorization

-0.087 €/m³ influent

CAS complemented with UF & RO paysfor itself !!!

CAPEX + OPEX of CAS = 0.60 €/m³ influent(Van Haandel and Van der Lubbe 2007;

Handbook biological waste water treatment)

(Verstraete et al. 2009; Bioresource Techn. 100, 5537-5545;LabMET)

Sewage as a resource of water

Case study: Koksijde, Belgium (IWVA)

(Dewettinck et al., 2001; Water Sci. Technol. 43: 31-38; LabMET)

Take home: This technology was upscaled in Singapore � NEWater

UF/RO NEWaterPRE-

CONCENTRATIONSCREENINGSEWAGE

COARSE MINERALS

ANAEROBICDIGESTER

FILTER PRESS

P-RICH CAKE

BIOGAS

NITROGEN-RICH WATER

COMBINED HEAT AND POWER

UNIT. THE CO2 GOES TO THE ALGAL FARM

NATURAL STABLE

FERTILIZER (NSF)

PYROLYSIS BIOCHAR

BRINE

(Verstraete et al. 2009; Bioresource Techn. 100, 5537-5545; LabMET)

“The A&B Line Technology” /The “Used Water” Factory

B-lineMinor flow (max 10 %)

A-line (Major flow)

Examples of pre-concentration (prevention of sewage dilution)

– Separate sewer system (rain water and waste water)

– 50 % less infiltration of ground water in sewer

– Domestic water conservation

– Use of kitchen waste

– Control microbial degradation

���� Already (5 – 10 times) pre-concentration possible

Crucial step = pre-concentration

(creating a pre-effluent easy cleanable with UF/RO

+ concentrate waste load with 10 – 20 times more COD/m³)

Sewage as a multi-resource

(Verstraete & Vlaeminck, 2010; Keynote Paper 2nd Xiamen International Forum on Urban Environment; LabMET)

Examples of pre-concentration (Physical/Chemical)

• (Direct) filtration

= filtration with or without coagulant

e.g. - Dynamic sand filtration (DSF)

- Membrane filtration

e.g. FMX and VSEP

• Dissolved Air Flotation (DAF)

Crucial step = pre-concentration

(creating a pre-effluent easy cleanable with UF/RO

+ concentrate waste load with 10 – 20 times more COD/m³)

Sewage as a multi-resource

Examples of pre-concentration (Biological)

• Adsorption Bio-Aeration or Boehnke concept

Crucial step = pre-concentration

(creating a pre-effluent easy cleanable with UF/RO

+ concentrate waste load with 10 – 20 times more COD/m³)

Sewage as a multi-resource

(Boehnke et al. 1998; Water-Engineering & Management 145, 31-34)

Cost consideration for the proposed sewage recycling technology (according to C2C) � the major flow: directly to reuse� the minor flow (= a concentrate): produced at the entry of the plant,

subjected to advanced recovery for energy and fertilizers

Sewage as a multi-resource

Major flow

Dissolved air flotation 0.02-0.03 €/m3

Dynamic sand filtration 0.05-0.06 €/m3 0.53-1.15 €/m3

Ultra filtration and Reverse Osmosis 0.46-1.06 €/m3

Minor flow

Anaerobic digestion Break even

Mechanical separation 0.08-0.10 €/m3 0.08-0.10 €/m3

Pyrolysis Break-even

Total costs*: 0.61-1.25 €/m3

* this is the estimated total cost(Verstraete et al. 2009; Bioresource Techn. 100, 5537-5545; LabMET)

Take home: Total bruto costs of about 1 €/m3 for the A&B line technology are comparable with those of CAS

Sewage as a multi-resource

(Verstraete & Vlaeminck, 2011;Int J Sust Development and World Ecol 18: 253-264 LabMET)

The overall biorefinery / ““““used water ““““ factory :

Life Cycle Assessment or LCA

is a process to evaluate the

environmental burdens

associated with a product,

process or activity by identifying,

quantifying and assessing energy

and materials used and wastes

released to the environment

Evaluate sewage treatment plant with LCA

Evaluate sewage treatment plant with LCA

Take home: Wastewater treatment still has a relatively largeshare in the environmental pollution; this can be

decreased significantly by better ‘Urban mining’

Some mPE’’’’s of waste water treatment

ConventionalUsed water factory

Eutrofication 115 mPE

Ecotoxicity 85 mPE

Acidification 30 mPE

Global warming potential 18 mPE

(Clauwaert et al 2010; WT-Afvalwater 10, 186-195; Aquafin)

Sewage as a multi-resource

Energy gain (kWh IE−1 year−1) Avoided CO2 emission (kg CO2 IE-1 year-1)Electricity Heat

Kitchen grinder -1.4 -0.9

Advanced concentrator -6.0 -3.6

OLAND 12.8 6.6

Heat recovery -179 496 41.7

Anaerobic digestion 38.9 23.3

Sludge dewatering 1.8 1.1

N recovery -9.6 40.8 4.5

P recovery 1.2 2.0

Biochar 13.3

sum -141 537 88

Take home: The A&B line factory’’’’cuts 1-4 % of the CO2 emissions per IE

(Verstraete & Vlaeminck, 2010; Keynote Paper 2nd Xiamen Intern. Forum on Urban Environment; LabMET)

Take home:

The C2C design of the A& B line technology can already be achieved at equal costs of the CAS + it holds plenty of extra potentials

C2C designSewage as a multi-resource: Economically

CAS design: - Total cost without water recovery

≈ 1.0 €/m³ - Net costs upon sale of RO-permeate = 0.0 €/m3

A&B line design: - Total cost with up-recycling of energy &

nutrients ≈ 1.0 €/m³- Net costs upon sale of RO-permeate = 0.0 €/m3

Perspective: - CO2 recycling via algae

- Recovery of struvite

- C-storage as biochar

Overview • 1.The facts from the water industry

• 2. Incremental appraoches

• 3.Mavericks in the old line of used water treatment

• 4. The real step forward : closing the water cycle entirely – the “used water factory” and the development of the demand side

REE / P / FEED &FOOD + The Clearance Concept

• 5 .Conclusions

Metals / Rare Earths1.Granulated bacteria for upconcentration of metals, present at very low concentrations (µg – mg/L) in water streams:

2. Extraction of mono-sludge ashes : recover the metals ( clearing process ) , upgrade the remainder as P-fertilizer

C:\Users\Willy\Pictures\2014-01-

24_0813.png

3 .Food /Feed : Valuable biomass polymers

*Plenty of bacteria have ca 20% PHA on dry matter under

anaerobic conditions

* Can be increased to 60% under micro-aerophilic

conditions

(Salehizadeh & van Loosdrecht, 2004; Biotechnol. Adv. 22:

261-279)

* Can be used for

a) PHA : to produce plastics ( Veolia /Brussels )

b) PHB : as a prebiotic for animal feed

Patent Ugent / LabMET / Kemin(Defoirdt et al. 2007; FEMS Microbiol Ecol 60: 363-369; LabMET)

+ Carbohydrate

+ Aeration

Fish feed with

20-40% protein

Protein

Carbohydrates

About 20%

becomes fish

protein

Waste N, P, …

Microbial SCP

Fish (Talapia) Extra 25% recovered as

fish protein

80%

= BFT

Direct recycling of fecal N as feed in aquaculture

(Crab et al., 2007; Aquaculture 270: 1-14; LabMET; (De Schryver et al. 2008; Water Res. 42: 1-12; LabMET )

► Fecal cycles in short loop can work

Production of SCP in intensive husbandry aquaculture

The BioFloc Technology is a fact . Taboo’s can change !

Anaerobic

Digestion

Organic waste

streams

Digestate

‘Liquid’

Additional nutrients

LFOS(Liquid fertilizer on spec)

‘Solids ’ P-Carbon(Better humus in agricultural soils)

Biogas

Green gas (eg car fuel)

CO2

Hydrogeno

Trophic

BioreactorElectrolysis

Excess

(Green)

Power

Water

Torrification

O2

H2

Carbon DioxydeCDprotein(Feed/Food)

4.AD Clearance

IWA -RRfW : the clusterListing the issues

• Resources possibly recovered from water & sludge– Heat / energy (gases , liquids , solids )– Nutrients N , P , K– Fats , oils , greases (FOGs)– Fibers / Carboxylates / PHA /….– Amino acids chelated trace elements fertilizer ( Liu et al 2009 , J

Hazard Mater 15:1159-1167– Rare earth elements (REE ) (Zan lin etal . ACS Apllied Materials

and Interfaces ….)– Heavy metals : Cu by the BioSulphide process (Saniedanesh et

al .2013; PSE ASIA 25-27 june Kuala Lumpur )– Char for soil amendment – Proteins for feed or for adhesives (Pervaiz 2012; Unvi of

Toronto) )

– ……..

IWA Resource Recovery Cluster • The launch : IWA World Congress Lisboa 2014 ; you can register already

• The concept :

*Plenty of actions on the push side

but

Particularly the pull side must be developed

To achieve this , we need 3 things

- Paradigm shift : recovery can be conceptually ‘cleared‘ if we call a spade a spade

- Dimensions of scale shift : think markets of

10 000 tons per year

- Delivery on spec

• The energy consumpton by the water industry is important ( up to 1% of national electricity ) and is increasing

• Good housekeeping in conventional WTP can cut the energy costs by 20-40%

• Plenty of incremental approaches are underway ; each penny counts ….

• Mavericks such as Nereda , Demon .. are welcome

• We really must dare to go for the ‘used water factory fully focussed on recovery ‘

Recap on RRfW

Conclusions

* The driver for transition is to help to decrease climate change

* We have to redesign the sewage system entirely-Separation at source : clever ‘at home treatment’

-Separation at STP : conventional CAS is outdated !!!!Go for the A&B Line Technology

*Pre-concentration is a crucial step ;AD is a key process in the recovery of Energy and Nutrients

*Resource Recovery from used water is all about organizing the DEMAND side