Anaerobic Fluidized Bed Membrane Bioreactor Treatment of Domestic Wastewater for Potential Reuse

Perry L. McCarty Department of Civil and Environmental Engineering Stanford University

What is the Best Option for Capturing Wastewater’s Resource Potentials?

Water

Other

Chungheon Shin

Prof. Jaeho Bae

Prof. Jon Kim

Question • Can we treat municipal wastewater 100% anaerobically to achieve net energy production while meeting effluent quality standards, and at lower cost than by conventional aerobic treatment ?

Fluidized Bed Anaerobic Treatment of Industrial Wastewaters Objective – High SRT and short HRT

Staged Anaerobic Fluidized MBR (SAF-MBR)

Methane

Methane Particles Membranes GAC Recycle Recycle

Influent TCOD 523 mg/L Influent

First Stage FluidizedFirst Bed Stage Reactor

Effluent Effluent TCOD 60 mg/L

Permeate

Permeate

Second Second Stage Stage with membrane Membrane Bioreactor

Kim et al., Environ. Science & Technology, 45:576(2011)

Sparging Techniques to Reduce Fouling Gas Bubbles

Particles

Gas Recycle

Traditional Gas Sparging

d d d d

Water Recycle

New Particle Sparging

12 m3/day (6 h HRT) SAF-MBR Pilot Plant Treating South Korea Primary Effluent

Fluidized Bed Reactor

Membrane Bioreactor

Membranes

Pilot SAF-MBR Operation • Domestic Wastewater characteristics – COD – BOD5

300 ± 60 mg/L 160 ± 45 mg/L

• Hydraulic Retention Time – AFBR – AFMBR – Total

• AFMBR Flowrate

2 hours 2.6 to 4.8 hours 4.6 to 6.8 hours

4 to 7 m3/d

SAF-MBR BOD5 - % Removal vs. Temperature Temp. Range oC

}

Percent Removal

100

2015

148

1525

2632

2514

139

95 90 85 80 75 70 0

100

200 300 400 500 Day of Operation Shin et al., Bioresource Technology, 159, 95-103 (2014)

Temp.

}

2015

148

1525

2632

2514

1309

USA EPA Upper Limit

mg/L

Range oC 45 40 35 30 25 20 15 10 5 0 0

SAF-MBR Effluent BOD5

100

200

300

400

500

Day of Operation Shin et al., Bioresource Technology, 159, 95-103 (2014)

Biosolids Production 0.05 kg VSS/kg COD and already digested and less than half that from aerobic treatment Shin et al., Bioresource Technology, 159, 95-103 (2014)

Superior removal of pharmaceuticals: Anaerobic (SAF-MBR) vs aerobic treatment

SAF-MBR at Stanford McCurry et al., Environ. Sci. & Technol. Letter, 1:459, 2014

Aerobic MBR Has High Energy Requirement kWh/m3 Conventional Aerobic Activated Sludge Conventional Aerobic with Nitrification Aerobic Membrane Bioreactor Conventional Aerobic with RO Seawater Desalination

0.6 0.8 1.0 2.5 4.5

Electrical Energy Balance – kWh/m3 Energy requirement*

AFBR AFMBR Total

GAC

Membrane

Total

CH4 Energy Potential**

0.016 0.210 0.226

0.001 0.001

0.016 0.211 0.227

0.139

* Assumes 65% pump efficiency ** Assumes 33% efficiency converting methane to electricity, primary digester gas not included Shin et al., Bioresource Technology, 159, 95-103 (2014)

Electrical Energy Balance – kWh/m3 Energy requirement* GAC

AFBR AFMBR Total Total

Membrane

Total

0.016 0.016 0.210 0.001 0.211 0.226 0.001 0.227 But with hydraulics change: 0.132 0.001 0.133

CH4 Energy Potential**

0.139

* Assumes 65% in pump efficiency ** Assumes efficiency of 33% to convert methane to electricity, primary digester gas not included Shin et al., Bioresource Technology, 159, 95-103 (2014)

Separation of organism SRT from bulk VSS SRT – allows keeping reactor VSS low with a low HRT Clear Permeate

Influent With VSS

VSS VSS

Organisms on GAC – not wasted

VSS – 500 to 1400 mg/L

d d

d

d

d d

d

d

d

d

d

d

d

d

d

Recycle line

VSS wastage – few organisms

Winter COD Mass Balance 10 % Permeate 36% Dissolved Methane

9 % Unknown 11 % Biosolids Wasting 11 % Sulfate Reduction 23 % Gaseous Methane

SAF-MBR Advantages Over Aerobic MBR Treatment SAF-MBR • Energy neutral • 1.4 Liters Biosolids/m3 • Heat energy sufficient to dry biosolids • 96% median emerging contaminants removal

Aerobic MBR • 1.0 kWh/m3 • 2.8 Liters Biosolids/m3 • Heat energy insufficient to dry biosolids • 76% median emerging contaminants removal

Irrigated land

Monterey County Water Recycling Project Water Reclamation Plant

Monterey Regional Water Pollution Control Agency Recovers Water, Energy, and Nutrient Resources • Largest irrigated crop wastewater recycle in U.S. • Produces 76,000 m3/day recycled water

• Irrigates 5,000 hectares • Through anaerobic biosolids treatment and cogeneration, produces 50% of WWTP’s energy needs • No energy wasted for nitrogen oxidation – all is used as plant fertilizer

Monterey Water Reclamation Plant

Google - 2014

Monterey Water Reclamation Plant SAF-MBR Footprint

Google - 2014

Singapore SAF-MBR Pilot System Prof. Liu Yu, Nanyang Technological University

Codiga Resource Recovery Center Stanford’s Pilot-scale test bed facility

Director Craig Criddle Wastewater and Waste Organics

High Value Products

Conclusions • Complete and efficient anaerobic MBR treatment of domestic wastewaters now appears possible at temperature as low as 8 oC • Anaerobic treatment produces rather than consumes energy and significantly reduces biosolids production and treatment footprint • Anaerobically treated wastewater reuse for agriculture and landscape irrigation is a potential approach for more complete resource recovery

Financial Support • World Class University Program, Science and Technology, Ministry of Education, National Research Foundation of Korea • Korea Ministry of Environment • Inha University Research Grant

Thank you!