WASTEWATER MANAGEMENT IN THE 21ST DISCUSSION TOPICS CENTURY: CHALLENGES, TRENDS, AND FUTURE OPPORTUNITIES • Impact of disruptive events on wastewater management World Bank Seminar • Trends in wastewater treatment DISRUPTIVE TECHNOLOGIES FOR • Comprehensive source control for POLLUTION MANAGEMENT potable reuse Washington, DC December 12, 2018 • The future: Integrated wastewater management • Take home thoughts George Tchobanoglous Department of Civil and Environmental Engineering University of California, Davis
CONSEQUENCES OF CLIMATE CHANGE
DISRUPTIVE EVENTS: • Sea level rise and surge flows due to LAW OF UNINTENDED CONSEQUENCES hurricane events ON WASTEWATER MANAGEMENT • Areas that are wet are getting wetter Outcomes that were not anticipated, foreseen, or predicted by a purposeful action • Areas that are dry are getting dryer CLIMATE CHANGE • But of greater importance is the WATER CONSERVATION intensity of rainfall events • Must learn to live and deal with higher levels of environmental pollution
UNINTENDED CONSEQUENCES OF TREATMENT STORMWATER PEAKS DUE TO RAINFALL INTESITY PLANT LOCATION BECAUSE OF SEA LEVEL RISE AND SURGE FLOWS DUE TO CLIMATE CHANGE
For example, if a peak flow of 3 to 1 can be handled, then the the stormflow must be diverted between about 8:30 and 12:30
1 THINKING ABOUT WASTEWATER CONSTITUENT IMPACT OF WATER CONSERVATION CONCENTRATIONS IN LIGHT OF WATER CURRENT AND PROJECTED PER CAPITA WATER USE CONSERVATION: PAST AND PRESENT IN THE UNITED STATES
• In the past, terms such as low, medium, and high strength were used to describe wastewater constituent concentrations • Today, such terms can and should no longer be used to describe wastewater constituent concentrations, especially in light of climate change • What must be done is to consider the average constituent mass discharged per person and the volume of water into which the waste is added
TO ASSESS IMPACT OF WATER CONSERVATION ON MASS OF WASTE CONSTITUENTS DISCHARGED WASTEWATER CONCENTRATIONS, MUST CONSIDER BY INDIVIDUALS IN VARIOUS COUNTRIES MASS OF WASTE DISCHARGED BY INDIVIDUALS
Based on dry mass
IMPACT OF WATER CONSERVATION ON DATA FROM THE CITY OF SAN DIEGO WASTEWATER CONCENTRATIONS
Based on dry mass
2 IMPACT OF WATER CONSERVATION AND DROUGHT:
SOLIDS DEPOSITION, H2S FORMATION, AND DOWNSTREAM CORROSION DUE TO REDUCED FLOWS COLLECTION SYSTEM DESIGN ISSUES
• Reduced flowrates • Increased exfiltration • Changing water use patterns • Flowrate peaking factors not based on use of low-flow fixtures
EXISTING DESIGN APPROACH IS INADAQUATE AND NEEDS TO BE UPDATED
DISRUPTIVE EVENTS IN WASTEWATER TREATMENT PARADIGM SHIFT IN VIEW OF WASTEWATER FOR THE 21ST CENTURY • Paradigm shift in view of wastewater • Recovery of energy from wastewater • Enhanced preliminary treatment WASTEWATER is a RENEWABLE • Alternative primary treatment processes RECOVERABLE SOURCE of • Enhanced primary treatment POTABLE WATER, RESOURCES, • Alternative wastewater technologies • Design for alternative endpoints and ENERGY • Comprehensive source control for potable reuse • Integrated wastewater management
FATE OF CHEMICAL ENERGY DURING FATE OF CHEMICAL ENERGY DURING WASTEWATER TREATMENT WASTEWATER TREATMENT
Fundamental question: What is the optimal use of the Fundamental question: What is the optimal use of the carbon in wastewater? carbon in wastewater – energy production, nitrogen removal, resource recovery or a combination thereof?
3 SETTLING CHARACTERISTICS OF GRIT IN WASTEWATER COLLECTION SYSTEMS
ENHANCED PRELIMINARY TREATMENT
Source: Wastewater Engineering, 5th ed, McGraw-Hill, 2014
MULTI-TRAY GRIT SEPARATOR: A DEPARTURE FROM CONVENTIONAL DESIGNS ALTERNATIVE PRIMARY TREATMENT PROCESSES
Source: Wastewater Engineering, 5th ed, McGraw-Hill, 2014
ALTERNATIVE TECHNOLOGIES FOR PRIMARY ALTERNATIVE TECHNOLOGIES FOR PRIMARY TREATMENT: CLOTH SCREEN (200-300 μm) TREATMENT: CHARGED BUBBLE FLOTATION
• 1/5th the size of conventional clarifiers • Nanoparticles can be added to charged bubble for removal of specific constituents
4 ALTERNATIVE TECHNOLOGIES FOR ENHANCED PRIMARY TREATMENT: CLOTH DISK FILTER (Pore size 5-10 μm) FLOW DIAGRAM FOR PRIMARY FILTRATION
Vacuum suction head
Fiber thickness = 0.007 mm Depth filter L/D = 400 to 800 Cloth filter L/D = 425 to 725
Courtesy Kennedy Jenks Consultants
CLOTH DISK FILTER INSTALLATION TYPICAL PERFORMANCE FOR AT LINDA WWTP, LINDA, CALIFORNIA PRIMARY EFFLUENT FILTRATION
Courtesy Kennedy Jenks Consultants
ALTERING THE CHARACTERISTICS OF RAW WASTEWATER FOR ENHANCED DOWNSTREAM TREATMENT
KINETIC COEFFICIENTS BASED ON PARTICLE SIZE ENHANCED PRIMARY TREATMENT
5 ENHANCED PRIMARY TREATMENT WITH PRIMARY EFFLUENT FLOW DIAGRAM FOR PRIMARY FILTRATION FILTRATION (PEF) BEFORE BIOLOGICAL TREATMENT AND PRIMARY EFFLUENT FILTRATION
Compressible medium filters
Courtesy Kennedy Jenks Consultants
REPLACE AND REPURPOSE EXISTING TREATMENT TANKAGE
ALTERNATIVE BIOLOGICAL TREATMENT TECHNOLOGIES
Anaerobic granular sludge
CHARGED BUBBLE FLOTATION FOR ALGAL POND EFFLUENT REUSE
DESIGN WASTEWATER TREATMENT FOR ALTERNATIVE END POINT Flotation tank Dewatering tank Chemical mixing tank FOR POTABLE REUSE
Thickened algae ~4-5% Effluent turbidity typically, <1 NTU
Dewatered sludge being prepared for composting
Pasteurization for disinfection Compressible medium Lagoon feed water effluent filtration Algae dewatered on straw bed
6 MEASURES TO IMPROVE PERFORMANCE AND OPPORTUNITY TO RETHINK DESIGN OF ENHANCE RELIABILITY OF EXISTING AND NEW WWTPs WASTEWATER TREATMENT FOR POTABLE REUSE
INTEGRATED WASTEWATER MANAGEMENT
THE FUTURE: INTEGRATED WATEWATER MANAGEMENT INCLUDING POTABLE REUSE
TAKE HOME THOUGHTS
• Must consider unintended consequences of alternative wastewater management strategies • Must think differently about the uses of carbon in THANK YOU wastewater • Must be open to new treatment technologies FOR LISTENING • Must implement integrated wastewater management
IT’S A NEW WORLD UNLEASH YOUR IMAGINATION!
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