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GMWEA Spring Conference
May 30, 2013
Green Project Elements Using Innovative, Energy Efficient,
Sustainable Design
Overview
1. Process for Assessment and Decision Making
2. Opportunities and Solutions
2A. Site
2B. Buildings
2C. Process and Controls
2D. Mechanical
2E. Electrical
2F. Biogas Cogeneration
3. Take Aways
Process for Assessment and Decision Making
What do Green Project Elements Include?
Green Infrastructure
•Stormwater solutions: Rain gardens, detention basins, buffers
•Site design: Porous pavement
Energy Efficiency
•Gas use
•Electricity use
•I/I reductions
•Wet weather storage
Water Efficiency
•Beneficial reuse of treated effluent
•Leak repair program
•Plumbing fixtures
Repurposing
•Buildings
•Reducing impervious areas
•Tanks
•Treated effluent reuse
Sustainability
•Choosing durable materials with longer useful life
•Waste reduction
•Stormwater BMPs
Matrix of Potential
Objective:
• Identify items included and not included
• Identify all potential improvements
• Identify and document potential benefit
Industry Resources
• Industry resources
• Review age of equipment
• Review equipment operations and controls
Identify Potential
Improvements
Energy Efficiency - Where to Start?
Establish an energy baseline
• Identify equipment with highest energy use – Wastewater Example
• Blowers/Aeration
• Pumps
• Dewatering
• HVAC
Decision Making Process
• Evaluation Criteria
• Capital cost
• Annual O&M Cost
• Available funding sources
• ROI: Return on investment
• Feasibility
• Complexity
• Reliability/track record of emerging technologies
Determine Objectives
Economic
Sustainable Social
Examples
• Worked with various participants and stakeholders
Town of Hartford White River Junction and Quechee WWTFs
• Green Project Elements Workshop
• 7 year return on investment (ROI) Village of Essex Junction WWTF
• Energy Savings Scoping Study Champlain Water
District
Town of Hartford Quechee & White River Junction WWTFs
Participants/Stakeholders
• Town Staff
• Town Energy Committee Members
• State
• Facilities Engineering
• Wastewater Management Division
• EPA
• Efficiency Vermont
Green Project Elements Workshop
• Owner
• Staff
• Board Members
• Energy Committee
• Design Team
• State of Vermont
• EPA
• Efficiency Vermont
• VRWA
• Local Industry
Champlain Water District
Funded by Efficiency Vermont
Energy Saving Scoping Study
• Raw Water Intake
• Water Treatment Facility
• Four Pump Stations
• Transmission System
Established baseline: Pumping accounted for 84% of overall electrical usage at CWD facilities
Champlain Water District - Recommendations
Pump Control Efficiency
• Operational modifications
• Optimize VFD redundancy versus fixed speed operated pumps
• Using 1 VFD pump to trim flow to the desired amount rather than running multiple pumps at similar speeds
• Soft starts on fixed speed pumps to limit power spikes
• Pump replacement – right sizing the pump to improve efficiency
• Pumps operating at significantly lower head than original design head
• Funding
• CWD allowed to reinvest energy fees into energy improvements
Opportunities & Solutions
Opportunities & Solutions
Site
Buildings
Process and Controls
Mechanical
Electrical
Biogas Cogeneration
Site
Site – Porous Pavement
Porous Pavement: Improves stormwater management by allowing passage of surface runoff to infiltrate into ground
Site – Porous Pavement
Examples:
•Hartford White River Junction WWTF
•Hartford Quechee WWTF
•Essex Junction WWTF
Site – Porous Pavement
Benefits:
• Reduces impervious area
• Eliminates need for additional stormwater treatment
Lessons Learned:
• Requires sweeping and routine maintenance
• Need suitable permeable soil conditions
• Limited durability – use in low traffic areas
Buildings
Buildings - Repurposing
Examples:
• Hartford White River Junction WWTF
• Renovated existing Control Building
• Aeration tanks converted to SBR tanks
• Secondary clarifier converted to sludge storage
• Essex Junction WWTF
• Original filter building converted to chemical feed/storage building
Benefits:
• Minimizes new construction
• Doesn’t increase impervious area
Lessons Learned:
• Not necessarily less expensive
• Creates more sequencing issues during construction
Buildings – Solar Collector Walls
Mounted a few inches from building’s outer wall.
Perforations in wall allow outside air to travel through wall and through the panel, then to the building’s ventilation system.
Summer bypass system
Buildings – Solar Collector Walls
Examples: Essex Junction WWTF
Benefits: Reduced heating and cooling costs
Buildings – Daylighting
Maximize opportunities for daylighting building space
• Window, skylight placement considered in building design to maximize use of light and solar gain
Benefits:
• Reduced electric lighting and heating usage
Buildings – 2011 Vermont Commercial Building Energy Standards
Building Envelope
• Higher R-values for building insulation required for roofs and walls
• Increased building material cost
Process & Controls
Grit Removal Systems - Vortex
Non-mechanical grit removal
• Gravitational forces used to separate grit from water
• No external power source
• No internal moving parts
• Installed as free standing structure or in concrete structure
Examples
• Hartford Quechee
• Hartford White River Junction
• Middlebury
Benefits
• Lower energy usage
• Smaller footprint
• Less concerns about odors
Lessons Learned
• Provide screening upstream to reduce plugging of grit removal line
Grit Removal Systems - Vortex
Biological Nutrient Removal
Removal of BOD5, phosphorus, and nitrogen through biological process
Anaerobic Selectors - Benefits
Green Project Benefits
• Enhances biological phosphorus removal
• For lagoon systems – increases BOD removal
• Reduces chemical usage and sludge generation
• Less sludge to dewater and dispose
• Decrease volume of RAS that needs to be pumped
Examples - Facilities with Biological Phosphorus Removal
Phosphorus: Create conditions for phosphorus accumulating organisms (PAO) to thrive
• Anaerobic Selectors
• SBRs
Conventional Activated Sludge
• Essex Jct WWTF
• Springfield WWTF
Oxidation Ditch: Fair Haven
Extended Aeration: Enosburg Falls
Aerated Lagoon: Hardwick
SBRs
• Hartford Quechee and White River Junction
• Shelburne
• Middlebury
Anaerobic Selectors Process Schematic
Anoxic Stage 1
Anaerobic Stage 2
Aerobic Secondary
Clarifier
Return Activated Sludge (RAS)
Primary Effluent Metal Salt Addition (Alum)
Addition of anoxic zone for denitrification (nitrate removal)
Anaerobic Selectors – Lessons Learned
Lessons Learned
• Requires anoxic for denitrification to optimize biological phosphorus removal
• Mixing is required and consider type of mixer for reliability
• ORP automatic monitoring for process control
• Reduced RAS return rates
Hyperbolic Mixers
More energy efficient option for mixing compared to submersible mixers
• Require ~40% less energy to achieve equal mixing
Hyperbolic Mixers
Examples
• Essex Junction WWTF
• South Burlington Airport Parkway
Benefits
• Lower Energy Required for Mixing
• Fewer units required
• Improved reliability over submersible mixers
• Motor accessible for maintenance
Converting fixed speed motor operation to variable frequency drive (VFD) operation
• Equipment is designed for peak flows
• VFDs allow equipment motor to run at partial load to save energy at average flows at design year
• Automatic or manual
• Eliminate throttling valves
• Improved process flow control
VFD Operation – Pumps & Blowers
Benefits:
• Improves energy efficiency through range
• Provides better process control
Lessons Learned:
• Locate VFD close to equipment
• Addition of VFD slightly reduces energy efficiency
• Use wall mounted units vs. cabinets
• Replace soft starts and can be used for phase converters
• Maintain minimum velocities in force main at low set speed
VFD Operation – Pumps & Blowers
Inefficiency in oversized pumps & blowers for design
Examples
• Champlain Water District
• Essex Junction WWTF
Lessons Learned
• Multiple units – sometimes 3 vs. 2 units
Right Equipment Sizing
Turbo Blowers
• New blower technology available in US for ~5years
• Operate at a very high speed
• Manufacturers:
• Aerzen (formerly K-Turbo)
• Neuros APG
• Atlas Copco (HSI)
Turbo Blowers
Turbo Blowers - Examples Essex Junction WWTF: HSI
Hartford White River Junction: HSI
Burlington WWTF: KTurbo
South Burlington Airport Parkway: KTurbo
Benefits
• Smaller footprint
• Includes internal variable frequency drive
• Greater capacity per BHP compared to other types of blowers
• Doesn’t run hot
• Quieter
Turbo Blowers - Benefits
Lessons Learned
• Good incentives provided by Efficiency Vermont
• Doesn’t have the wide turndown (operating range) claimed
• Better application in sizes > 100 HP
• Automatic control can be problematic in parallel operation with other types of blowers
• Long-term reliability still a concern
Turbo Blowers - Lessons Learned
Solar Aerators
Solar aerators supplement or replace the mixing/aeration in lagoons & ponds
Lagoon Aeration – Swanton WWTF
Item Description Original Proposed
Average Daily Flow 0.9 mgd 0.9 mgd
Peak Hour Flow 2.2 mgd 2.2 mgd
Aerators
Type Grid Powered Solar
Number 16 5
Power Requirements each unit 5 HP
3 x 80 watt
photovoltaic panels
Solar Aerators – Lessons Learned
Good incentive through Efficiency Vermont
Lease arrangements available
Shouldn’t be used to replace original aeration system, but operated to supplement
Haven’t been in operation long enough to determine long-term reliability
Instrumentation
Monitoring
• DO – Pacing blowers to meeting DO concentration set point
• ORP – Process control for biological nutrient removal
Flow pacing chemicals
Benefits
• Optimizes energy usage
• Improves process control
Non-potable Reuse
Optimizing use of plant water in lieu of potable water
Benefits
• Reduces municipal potable water use
Lessons Learned
• Filtering may be required
• Covering of tank may be needed to minimize algae growth
Mechanical
Mechanical – Heat Recovery System
Example
• Hartford White River Junction
• Transfer excess heat generated in blower room to other spaces
• Essex Junction WWTF
• Solar collector walls pre-heat air for ventilation
Benefit
• Reduced heating energy and energy costs
Buildings – Heat Recovery
New Code requirements
• NFPA 820 – Fire Protection
Class I, Div 1, Group D Spaces - NFPA 820 requires 12 air changes per hour for continuous ventilation and 30 air changes per hour if intermittently ventilated
• Headworks
• Primary Sludge Pumping
• Influent Pumping
Challenge in winter to heat buildings when drawing in cold air to meet ventilation requirements
Opportunity for heat recovery to reduce heating energy use
Mechanical – Heat Pump Systems
Use of treated effluent for heating/cooling
Mechanical – Heat Pump Systems
Hartford White River Junction WWTF
Essex Junction WWTF
Mechanical – Heat Pump Systems
Benefits
• Beneficial reuse of effluent
• Reduces energy usage for heating and cooling
Lessons Learned
• Maintain storage in chlorine contact tank
• May want to cover chlorine contact tank to minimize algae growth
• Filter or straining is needed
Mechanical – Geothermal Wells
Used to supply building heating and cooling
Two Types:
• Open Loop: Water from well(s) as conductor
• Closed Loop: Earth/ground as conductor
Mechanical – Geothermal Wells
Example: Essex Junction WWTF
• Open loop system
Benefits:
• Delivers 3-5 times more heat than the electrical energy
Lessons Learned:
• Open loop systems are more efficient
• System needs to be compatible with building heating system
• Well pump needs to be sized appropriately
Electrical
Solar Electric
Solar panels are used to generate electricity for on-site use or net metering
Example
• Hinesburg WWTF
• Montpelier WWTF
Benefits
• Reduces energy usage
• Reduces greenhouse gases
Lessons Learned
• Funding challenges – Public/Private Partnership
• Payback
Lighting
Lighting
Occupancy Sensors
Daylighting
Lessons Learned
• Incentives available from Efficiency Vermont
Biogas Cogeneration
Biogas Cogeneration
Methane gas from the anaerobic digestion process is used to generate electricity.
Requires pre-treatment with gas conditioning for siloxanes and/or hydrogen sulfide and moisture removal
Power is generated by either microturbines or internal combustion engines
Biogas Cogeneration – Essex Junction WWTF
Gas production ~37,000 cfd
System Components
• Biogas Treatment
• Moisture Removal
• Siloxane Removal
• Combined Heat and Power (CHP) Module
• 120 kW Engine
• Generator
Biogas Cogeneration - Benefits
Benefits
• Use of methane gas for electrical generation reduces electrical costs
• “Plug & Play” - Engines are available in container module
• Engine vs. microturbines
• Higher electric and thermal efficiencies
• Better turndown
• Gas compression system is not required
Biogas Cogeneration – Lessons Learned
Lessons Learned
• Good incentives from Efficiency Vermont
• Need to determine if sufficient gas production is available
• Gas treatment is necessary for siloxanes and hydrogen sulfide plus moisture removal
• Microturbines are not available or supported in smaller sizes
• Be aware of space classifications - some equipment may need to be exterior
Take Aways
Take Aways
Many of these opportunities should be standard for most large upgrade projects
Communicate and share experiences with other facilities and stakeholders
Public education and outreach for customers on green project elements
Solutions need to provide reasonable Return on Investment (ROI) of 7 to 10 years
Explore and leverage all public/private funding opportunities
Understand the complexity, reliability, and O&M costs of newer technologies
Questions?
Presentation is Available at:
www.AEengineers.com