Green Project Elements Using Innovative, Energy Efficient, Sustainable Design GMWEA Spring Conference May 30, 2013
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 Identify equipment Potential • Review Improvements equipment operations and controls
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 Economic • Capital cost • Annual O&M Cost Determine • Available funding sources Objectives • ROI: Return on investment Social Sustainable • Feasibility • Complexity • Reliability/track record of emerging technologies
Examples Town of Hartford • Worked with various participants White River Junction and stakeholders and Quechee WWTFs • Green Project Elements Workshop Village of Essex Junction WWTF • 7 year return on investment (ROI) Champlain Water • Energy Savings Scoping Study 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 State of Vermont • Staff • EPA • Board • Members Efficiency Vermont • Energy • Committee VRWA • • Design Team 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
Grit Removal Systems - Vortex 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
Biological Nutrient Removal Removal of BOD 5 , 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 Metal Salt Addition (Alum) Primary Effluent Secondary Anoxic Anaerobic Aerobic Clarifier Stage 1 Stage 2 Return Activated Sludge (RAS) 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
VFD Operation – Pumps & Blowers 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
Right Equipment Sizing Inefficiency in oversized pumps & blowers for design Examples • Champlain Water District • Essex Junction WWTF Lessons Learned • Multiple units – sometimes 3 vs. 2 units
Turbo Blowers 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 - Examples Essex Junction WWTF: HSI Hartford White River Junction: HSI Burlington WWTF: KTurbo South Burlington Airport Parkway: KTurbo
Turbo Blowers - Benefits Benefits • Smaller footprint • Includes internal variable frequency drive • Greater capacity per BHP compared to other types of blowers • Doesn’t run hot • Quieter
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