Innovative Tools for Energy Savings T. Allbaugh, P.E., S. J. Kang, Ph.D., P.E., K. Williams, P.E., W. Kramer, P.E., G. Jones, P.E., K. P. Olmstead, Ph.D., P.E., L. Thomas, M. Jessee, S. Westover, P.E. in Municipal WWTPs

Typical Energy Usage in U.S. Wastewater Treatment Plants Electricity at Average Plant: – 1500 kWh/Million Gallons (MG) treated for secondary treatment – Advanced Treatment Plant: 2000 to 3000 kWh/MG Other Energy Use – External supply of Carbon; methanol; Micro-C – Natural gas

Reasonable Expectations

Typical Power Use Distribution

Case History: Energy Optimization Study at 46 MGD Tertiary Treatment Plant Energy Optimization Team: Operation, safety, maintenance, administration Process optimization Utility bill and energy use analysis Develop alternatives and assess feasibility Life-cycle costing Priority ranking by team votes Funding decisions

YCUA WWTP Recently expanded for 46 MGD average design flow Tertiary treatment (biological P removal, filters, UV disinfection) Belt presses and fluid bed incinerator All flow is pumped to the site

Base Line Energy Costs $2.7 M at WWTP/year $0.4 M at pump stations/year Average 9 cents/KWH Team Goal : Save 5% or more

Average Power Use Before the Project 3708 KW

Average Power Use After Implementation 2655 KW

Aeration Blowers A centrifugal blower system supplies air to aeration, filter backwash, and clear well At current loadings, the power requirement could be reduced from 1,070 to 940 hp for one blower modification – COST: $76,000 – SAVINGS: $68,000 per year Payback in 14 months

Demand Anticipation Demand Charge = Single highest 30-minute integrated reading of the demand meter during on-peak hours In place for 12 months $13.75 per kilowatt Target decrease 300KW ($49,500/year) Defined protocol for operator response

Demand History

HV Controls in Solids and PSST Building Original HV equipment controls have been disconnected; system is presently being run manually Upgrade controls to Direct Digital Controls (DDC) with METASIS system – COST: $240,000 – SAVINGS: $140,000 per year Payback in < two years

Intermittent Ventilation for Process Areas Dewatering area, cake trucking area, and blower building not always occupied; continuous ventilation unnecessary Install local controls, METASYS programming, and H2S/O2 alarm systems to only turn on HVAC when areas are occupied – COST: $40,000 – SAVINGS: $43,000 per year Payback < one year

Incinerator Room Heat Recovery Space above fluid bed always HOT Boiler combustion air un-tempered in winter Adjacent dewatering area requires 12 air changes per hour Project provides additional heated ventilation to dewatering, and pre-heated combustion air for boilers

Building Lighting Philosophy Original design incorporated highly efficient lights on 100% of the time in galleries and process areas Changes incorporate slightly less efficient lights but provide immediate illumination

Lighting System Retrofit Fixtures are original, 1970s T12 fluorescent and metal halide High-Intensity Discharge (HID) lights Replace all T12 with T8 lamps– Non-HID fluorescent tubes with electronic ballasts – COST: $265,000 – SAVINGS: $110,000 per year Payback in < three years

Intermittent Ventilation of Drywells at Four Pump Stations Crews enter once per week for two hours Engineering standards call for: – Six air changes per hour, or – Thirty air changes for ten minutes Upgrade controls with SCADA – COST: $40,000 – SAVINGS: $21,000 per year Payback in two years

Adopted Plan Optimization Study Cost: $59,000 SRF Project Plan for $1.0M approved with 40% forgiveness of the loan principal, July 2009 Design and construction underway, Annual Cost Savings: $450,000, or 11% savings

Summary of Selected Projects DescriptionAnnual Savings Est. Capital Cost PaybackCurrent UsageExpected Usage% Reduction Aeration Blower $68,000$76,00014 months800 kW700 kW12.1 Demand Anticipation $50,000$160,0003 years, 3 months N/A Intermittent Process Area Ventilation $43,000$40,00011 months47 kW14 kW70 HV Control Upgrades $140,000240,0001 year, 9 months 750 kW370 kW51 Incinerator Room Heat Recovery $19,000$65, years--5 Lighting System $110,000$265,0002 years, 6 months 189 kW91 kW52 Intermittent Drywell Ventilation $21,000$40,0002 years107 kW15 kW86 TOTAL $451,000$886, kW1191 kW37

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