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