NSERC INDUSTRIAL RESEARCH CHAIR (IRC) PROGRAM (2017-2022)

SUSTAINABLE URBAN WATER DEVELOPMENT

Yang Liu, PhD, PEng

Associate Professor, Environmental Engineering

Canada Research Chair in Future Community Water Services

NSERC Industrial Research Chair in Sustainable Urban Water Development

University of Alberta 1

CURRENT CONVENTIONAL APPROACHES TO SANITATION (USE WATER ONCE, TREAT AND DISPOSE OF WASTE)

2Werner et al. (2009) Desalination, 248, 392-401

• Design based on the premise that excreta is a waste, and waste should be disposed of

• Loss of plant nutrients and trace elements in wastewater and eutrophication impact

• Assume that the environment can safely assimilate chemical and microbial waste

Design concept

• High cost long distance collection system financed up-front (30-50 year life) – centralized

• Energy intensive treatment processes

• Combined sewer overflow/bypasses – release sewage to the environment

• Water quality deterioration

Challenges

CURRENT ENERGY INTENSIVE WASTEWATER TREATMENT

Municipal wastewater treatment & collection are energy intensive

• Water services utilize ~3-7% of a nation’s electricity

• Oxygen supply is dominant energy consuming processes (55-70%)

Total energy content of municipal

wastewater is high

• ~23 W/(p.d) contained in COD, 6 W/(p.d) in NH4-N, and 0.8 W/(p.d) embedded in PO4-P

• New WWT processes have potential to capture most of the energy

Potential solution• Development of new wastewater treatment

options that are financed and based on resource recovery

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45%

8%22%

25%

Nitrification/denitrification

COD degradation

Sludge dewatering

Pumping and mixing

Net energy consumption at municipal wastewater treatment plant

RESOURCE RECOVERY BASED WASTEWATER SERVICES

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Circular Economy Principles

• Develop new treatment strategies with the focus of resource recovery of energy, nutrients and organics, and polishing steps to maximize effluent reuse, leading to an energy neutral orenergy positive wastewater treatment within the urban water service system.

• Meet the need for new urban developments and redevelopment of existing water service infrastructure.

IRC Objectives

• ‘Waste’ is food

• Diversity is strength

• Energy from renewable sources

• Systems thinking

RESOURCE RECOVERY OPTION 1: SOURCE-DIVERTED COLLECTION SYSTEMS

RESOURCE RECOVERY OPTION 2: CONVENTIONAL COLLECTIONSYSTEMS

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C, P, N, Krecovery

CH4 as Bioenergy

CH4

CO2

Land

Reduced transport cost

Food

Stormwaterfiltration

Bathing quality

Lower P, NHigher water

quality

Black Water < 30% volume > 50% organics > 90% N,P

Grey Water>70% volume

SOURCE-DIVERTED WASTEWATER MANAGEMENT SYSTEMS

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CURRENT PRACTICE ON SOURCE-DIVERTED RESOURCE RECOVERY SYSTEMS

Under-developed

projects

Developed projects

The Netherlands by DeSah• Sneek (2005, 200 homes)• Venlo (200 p.e.), The Hague(4,300 p.e.),

Wageningen (170 p.e.)Germany• Flintenbreite, Lübeck (2002, 380 p.e.)

• Jenfelder Au, Hamburg (2017, 2,500 p.e.)China by Semizentral Germany• Qingdao (2016, 12,000 p.e.)

Alberta, Canada (1,700 p.e.)

Gent, Belgium (430 houses)

Helsingborg, Sweden (320 houses)

Den Haag, NL (1,200 homes)Mr. Ken PacholokProf. Nicholas Ashbolt

Raw Sewage

Denitrifying methanotrophs

Air

Aerobic polishing

UASB NitritationSettler Digester

Air

Reuse/ Discharge

Greywater

Aerobic Granular Sludge

Air

Blackwater

Nitritation/ Anammox

Aerobic Granular Sludge

Air

Reuse/Discharge

UASB Struvite

Air

Source Diverted Wastewater

Conventionally Collected Wastewater

Reuse/Discharge

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RESOURCE RECOVERY STARTS WITH A TOILET

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Urine-diversion or standard dual flush toilet

JETS Vacuum toilet Propelair® Air-water forced toilet

3L /6L water per flush 0.5L water per flush 1L water per flush

BLACKWATER FROM DIFFERENT TOILETS

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Observations•BMP of vacuum toilet collected blackwater was ~31% lower at 35°C, as compared to conventional toilets

•Significantly reduced microbial diversity was detected in reactors with low flush toilet blackwater

Inhibition step tests concluded that•Methanogenisis step was inhibited for AD of low flush toilet blackwater•Free ammonia inhibition in vacuum collected blackwater, which was not realized previously•This issue would worsen with more water efficient toilets

Biomethane production potential

(BMP) decreases

OPTIONS TO ENHANCE DIGESTIBILITY - GRANULAR ACTIVATED CARBON (GAC) ADDITION

Blackwater free ammonia inhibition can be reduced through GAC addition• GAC mediate the interactions between fermenting bacteria and methanogens for methane production• GAC promoted enrichment of more conductive cultures, e.g., hydrogenotrophs, known to be more

tolerate to high free ammonia concentrations, and lead to an increase in CH4 % in biogas. 11

Interspecies hydrogen transfer

Direct interspecies electron transfer

BMP increased with GAC

OPTIONS TO ENHANCE DIGESTIBILITY

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Feed characterization

& selectionPretreatment

Microbial community

manipulation

Food waste co-digestion• 50% BMP increase

Thermal hydrolysis• No impactUltrasonication• 20% BMP increase

Conductive materials• GAC: 50% BMP increase• nZVI: No impact on BMP, 35% CH4 increase

in biogasH2 addition • 20% BMP increaseElectrochemical based processes• 35% BMP increase Continuous reactors for system optimization, and evaluation

of energy recovery effectiveness from different systems

LABORATORY CONTINUOUS REACTORS–ELECTROCHEMICAL BASED AD

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Blackwater fromwater-conserving toilet

Methane

Effluent

Discharge sludge

e- e-

LOW ENERGY N REDUCTION: ANAEROBIC AMMONIUM OXIDATION (ANAMMOX) PROCESSES

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Anammox processes lead to • ~63 % lower oxygen consumption • 100% reduction in supplemental carbon • ~80 % lower biomass production

Select bioreactor seeding strategies

Compare one and two reactor

configuration (combined PN/AMO)

Compare continuous vs. sequencing batch

operationCompare suspended growth vs. biofilms

(i.e., attached growth) bioreactors

Evaluate aeration strategies

(intermittent vs. continuous aeration)Examine the impact

of COD and P concentrations,

temperature, etc.

ANAMMOX OPTIMIZATION

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SUMMARY OF IRC TECHNOLOGY DEVELOPMENT

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IRC Technology Development (Source-diverted & Conventional Collection Systems) Anaerobic Digestion for Energy

Recovery from Organics

Anammox Processes for N Reduction

nDAMO/Anammox for N Reduction

Struvite Precipitation for Nutrient Recovery

Aerobic Granular Sludge for Polishing

PATH TO ADVANCING RESOURCE RECOVERY BASED TECHNOLOGY DEVELOPMENT

Process Fundamentals Technology Development

Process Evaluation & System Analysis

Reactor design and operation

Microbial population diversity, density and functional stability

Energy recovery and nutrient reduction efficiency

Anaerobic Digestion for Energy Recovery

Anammox for N Reduction

Struvite Precipitation for Nutrient Recovery

Aerobic Granular Sludge for Polishing

Process modelling

Life cycle assessment

Economics evaluation

System dynamics modeling for decision making

nDAMO/Anammox for N Reduction

KEY TAKE HOME POINTS

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“Traditional” urban water systems are not sustainable and tweaking existing systems often comprises the long term operation, hence a system thinking is needed to identify preferred site-specific configuration

Reactor configuration and operation conditions play important roles in controlling microbial population, pollutant removal kinetics and resource recovery efficiency

Advancing resource recovery system development requires the understanding of how detailed design decisions influence system sustainability.

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Acknowledgement

• All partners involved in this program: Natural Sciences and Engineering Research Council of Canada (NSERC), EPCOR Water Services, EPCOR Drainage Operation, Alberta Innovates, WaterWerx

• My collaborators: Drs. Nicholas Ashbolt, Evan Davies, Bipro Dhar

• My graduate students, postdoctoral fellows, and technical staff of the Environmental Engineering Group at the University of Alberta

Thank you!