water/wastewater treatment and sustainability dr. zuzana bohrerova ohio water resources center...
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Water/Wastewater Treatment and
SustainabilityDr. Zuzana Bohrerova
Ohio Water Resources Center
Civil, Environmental and Geodetic Engineering
Water Sustainability
What is sustainability?
Conference on Sustainable Development 2012 (Rio+20): Water is “at the core of sustainable development as it is closely linked to a number of key global challenges”
Water Sustainability
SOURCE: UN water.org, 2013
Triple bottom line approach to sustainability:ENVIRONMENTAL
ECONOMICSOCIETAL
Water Sustainability
• Are we using water in sustainable manner?
Water Use
Water Use
Water Footprint
SOURCE: UN water.org, 2013
• http://www.waterfootprint.org/?page=files/productgallery
Water Scarcity
• 41% of the world’s population lives in river basins suffering from moderate to high water stress
Water Quality
SOURCE: UN water.org, 2013
Achieving Sustainability Goals (UN)
• TARGETS (draft, after 2015)
– Universal access to safe drinking water, sanitation and hygiene
– Improve by x% the sustainable use an development of water resources in all countries
– All countries strengthen equitable, participatory and accountable water governance
– Reduce untreated wastewater by x%, nutrient pollution by y% and increase wastewater reuse by z%
– Reduce mortality by x% and economic loss by y% from natural and human-induced water-related disasters
Significance of Water Resources – U.S. perspective
Drinking water in US is among the best in the world, BUT
• Emerging contaminants threaten our water supplies– Microcystin, Perchlorate, Arsenic, PHACs
• Development in arid, coastal regions• Many waters are not “fishable and
swimmable”• Water/wastewater infrastructure security• Water x Energy Nexus issues
Current Urban Water Cycle
• Linear centralized treatment system based on disposal
WTP
WWTP
Groundwater or surface water inputs
(Q)
Waste sludge, brine (to disposal)
Waste sludge, brine (to disposal)
5% Q
5% Q
Loss to leakage(33%Q)
Outfall57-66% Q
City DistributionSystem
Current Urban Water Cycle
• Current urban wastewater management is linear treatment system based on disposal– Abuse of water for diluting human excreta– High cost for running and operating current systems– Collection infrastructure and fast development
• Need of sustainable, closed-loop urban wastewater management system based on conservation of water and nutrients
Approach to Water Infrastructure
Traditional New Sustainable
Rapid conveyance – underground concrete pipes and large treatment plants
Keep significant portion of the source, use, treatment, and/or disposal at the local level (site)
Goal – protect public health and receiving water, flood control
Expand to lighter ecosystem footprint and enhanced community benefits
Industrial model of specialization Integrate water, wastewater and stormwater – One water
Siloed infrastructure, funding, regulations and management
Multiple uses and reuses
Driver – economies of scales – bigger is better
True cost pricing - externalities
Potable water for all uses Water quality sufficient for intended use
Nelson, Sustainable Water Infrastructure
Water Energy Nexus• Water and energy systems are interdependent
SOURCE: DOE, energy.gov, 2014
Electricity Use for Water/Wastewater Treatment in US• Uses 4% of nation’s electricity• Majority for moving water/wastewater (80%), rest
treating• Groundwater supply as water source requires 30%
more electricity (versus surface water)• Increases in energy consumption:
– Age of delivery systems (friction increase, efficiency decrease)
– Conservation (systems will operate on below minimum level; trend to smaller system; economies of scale)
– Improve treatment requirements– Advanced wastewater treatment 3x more electricity than
trickling system
Drinking water treatment
• EPRI
Wastewater treatment
Decentralized vs centralized systems
Centralized Decentralized
Advanced collection and treatment Treated onsite
Out of sight More public participation
One technology for a regionFlexibility in process used and
management
More expensive for capital cost and operation and management
Expenses transfer to individuals
Control and regulation easy Hard to control and regulate
Lower spatial requirements per capita Space requirements
Operator expert Everyone expert
Some more sustainable WWT technologies- developing world
• Lagoons/wetlands– Climate– Land– Reuse potential?
• Anaerobic digesters (USAB)– Small and large scale– Biogas production and stable humus– Operation
• SAT (Soil Aquifer Treatment) technologies– Partially treated effluent used for recharge (Gaza)– Breaks pipe-to-pipe connection– Could lower WQ of groundwater
Evaluation Sustainability of WWTP
Muga and Mihelcic, 2008, Journal of Env. Management, 88:437-447
Wastewater operators
Land Requirements
Utility Services Leading Sustainability
From US EPA:• Alternative fuels• Automation• Resource recovery• Resiliency• Customer engagement – conservation• Investment in capital facility maintenance
Water Reuse
• Not the only solution• Needs to be combined with:
– water conservation– alternative water supply– green infrastructure– development in treatment technologies– environmental restoration
Water Quality Change
• Electricity consumption decreases sustainability of water reuse (LCA)
Reclaimed water use
Water Reuse for Irrigation
• Most reclaimed water contain TDS – salts• Irrigation needs to be evaluated for long term
sustainability of soil resources• Salt accumulation in soils – change in root osmosis
and ability to grow (uptake nutrients and water)• Israel about 70% reuse water used for irrigation –
salinity problem. – Strict source control (what is discharged into wastewater)– Changes in water softening agents and detergents
• Emerging contaminants
Domestic Water Reuse – dual reticulation
Water corporation, Australia, published online
Water reuse and treatment process
Reverse OsmosisAdvantages Disadvantages
Modular assembly system Water needs extensive pre-treatment
Installation cost low Interruption during stormy weather (too many organics in feed water)
High space/production capacity ratio
Need for extensive spare parts inventory
Low maintenance Brine disposal
Removes TDS Energy costs
Negligible environmental impact Needs reliable energy source
Minimal use of chemicals Membrane fouling
Future development: better membranes, lower energy requirements
San Diego
San Diego toilet to tap
• Facility available and treating wastewater• Regulations not in place• Public oppose direct potable use, but willing to use
as indirect potable use
http://www.sandiego.gov/water/purewater/demo/index.shtml
• Toilet to tap feasible – biggest hurdle is publicperception
Scientific American, CREDIT: Sam Kaplan; STYLING BY LINDA KEIL Halley Resources
Blue Print Columbus
• Sanitary sewer overflows has to be eliminated• Solution
– Green infrastructure– OARS deep sewer tunnel
http://www.youtube.com/watch?v=do6jFv_HdbE&feature=youtu.be
References
• Kennedy, L. and Tsuchihashi, R. (2005), “Is Water Reuse Sustainable? Factors Affecting its Sustainability. The Arabian Journal for Science and Engineering, 30(2C), 3-15
• Jhansi, S.C. and Mishra, S.K. (2013), “Wastewater Treatment and Reuse: Sustainable Options”, Consilience: The Journal of Sustainable Development, 10(1), 1-15