I l d id Sl d M t PlIsland-wide Sludge Management PlanSludge Processing Alternatives and Recommendations – Honouliuli WWTP

Review and Discussion

Project Background (2010-present)

• Defined sludge loadingsDefined sludge loadings

• Evaluated sludge options for all 9 WWTPs• Processing

H li• Hauling• Outlets

• Analyzed Risk, Reliability, and Redundancy

• Workshops w/ ENV WW , ENV Refuse, and DDC

• Screened out several options

Why should we care about Honouliuli WWTP?

• Fastest growing region in Oahu

• Second biggest WWTP on Oahu

S• Secondary treatment capacity to triple in 2024

• New developments around the WWTP

• Landfill will no longer except sludge• Landfill will no longer except sludge

H-POWER Introduction

• Owned by CCH, operated by Covanta• Receives & incinerates most of Oahu’s 

residential and commercial wasteT t t bi

MBU = Mass Burn Unitk “Thi d B il ”RDF = Refuse Derived Fuel 

• Two steam turbines• Generates 10% of Oahu’s electricity

aka “Third Boiler”300,000 tpy MSW

e use e ed ue300,000 tpy MSW each

Evaluation Findings

• The existing outlets do not provide enough capacity unless there is dryingg p g p y y g

• Drying is cheaper over the planning period

• Co-incineration of cake:

• recently implemented, limited operating data

• not practiced at RDF facilities

• Co incineration of dried biosolids successfully tested at H POWER• Co-incineration of dried biosolids successfully tested at H-POWER

• Significant amounts of energy can be recovered (tens of millions of $ worth over

the planning period)

Drying is recommended, but implementation and energy recovery is key

Outlets

Sludge Outlet Options

• Landfill • Synagro’s Land Application •  H-POWER

Sludge Outlet Options

• Landfill • Synagro’s Land Application •  H-POWER

S.I. Synagro Biosolids Reuse/Disposal

7% 5% 9%

2012 20135%

2%2014

88%

19%

72%93%88%

Cake Landfilled Pellets Landfilled Pellets Reused

Sludge Outlet Options

• Landfill • Synagro’s Land Application •  H-POWER

S.I. Synagro Biosolids Reuse/Disposal

7% 5% 9%

2012 20135%

2%2014

88%

19%

72%93%88%

Cake Landfilled Pellets Landfilled Pellets Reused

Cannot rely on land application alone

Additional Processes are Required to Utilize H-POWER

Either:Either:

1. Additional processes at Honouliuli WWTP (thermal drying), or

2. Additional processes at H-POWER (cake receiving stations)

Energy Generation is Critical to Selecting the Best Option

Either:

1. Generate electricity and heat at Honouliuli WWTP (CHP, gas sale)

or

2. Generate electricity at H-POWER by providing additional high-

energy feedstock (dried biosolids)energy feedstock (dried biosolids)

Loading and Capacity Considerations

60,000

Annual Load Total DT/yr Annual Load without Sand Island DT/yr

2 RDF Dry Capacity

40 000

50,000

ons p

er year)

Excess!

30,000

40,000

/Cap

acity

 (dry to

Good through planning

1 RDF Dry Capacity

MBU Cake + 1 RDF Dry Capacity

20,000

dge Prod

uctio

n/

Enough capacity through planning,excluding Sand Island

Sufficient for all till 2035

MBU + RDF Cake Capacity

10,000

Annu

al Slud

Almost at Capacity, Not sufficient past 2024

MBU Cake Capacity

MBU + RDF Cake Capacity

02015 2020 2025 2030 2035 2040 2045 2050

Year

p y, p

Loading and Capacity Considerations

Without drying at SI or HN, H-POWER cannot accommodate all CCH biosolids

Sludge Treatment Options

Two Options Evaluated in Detail

Option 1: Expanded Cake Receiving at H-POWER• MBU Cake Receiving & Feed Station• RDF Cake Receiving & Feed StationRDF Cake Receiving & Feed Station• HN Biogas → Onsite Electricity

Option 2: Thermal Drying at Honouliuli WWTP w/ H-POWER Receiving• MBU Cake Receiving & Feed Station• RDF Dry Receiving (no station required)• HN Biogas → Thermal Drying

Option 1: Cake Hauling

Option 1: Expanded Cake Receiving at H-POWER

Roll-off bins or dump trucks would be loaded with dewatered cake

Option 1: Expanded Cake Receiving at H-POWERDewatered cake from Honouliuli and other CCH WWTP would be hauled and fed to one of two cake receiving stations at H-POWER

Note:An MBU receiving station was recently constructed.

An RDF receiving station would be required for this option.

Option 1: Expanded Cake Receiving at H-POWER

Dewatered cake would be co-incinerated with MSW

Option 1: Expanded Cake Receiving at H-POWER

Ash would be removed and hauled as is current practice at H-POWER.

Option 1: Expanded Cake Receiving at H-POWER

In the event of H-POWER downtime, Honouliuli WWTP cake would be stored onsite

Option 1: Expanded Cake Receiving at H-POWER

Energy could be recovered from a new biogas CHP system at Honouliuli WWTP

Footprint Considerations – Option 1

64’ x 265’ Cake Storage Area

CHP

Option 2 Thermal Drying

Option 2: Drying at Honouliuli WWTP w/ H-POWER Receiving

Dewatered cake would be fed to a buffer silo or hopper

Cake from the hopper would be pumped t th it th l dto the onsite thermal dryer.

Option 2: Drying at Honouliuli WWTP w/ H-POWER Receiving

Biogas would be used as the dryer fuel to evaporate moisture from the cakeogas ou d be used as e d ye ue o e apo a e o s u e o e ca e

Indirect Drying – paddle or screw

Option 2: Drying at Honouliuli WWTP w/ H-POWER Receiving

Dried biosolids producted b oso ds p oduc

Option 2: Drying at Honouliuli WWTP w/ H-POWER Receiving

Dried biosolids would be conveyed to a storage silo

Option 2: Drying at Honouliuli WWTP w/ H-POWER Receiving

Trucks would be loaded w/ dried biosolids and hauled to H-POWERuc s ou d be oaded / d ed b oso ds a d au ed o O

Option 2: Drying at Honouliuli WWTP w/ H-POWER Receiving

Dried biosolids would be fed to the RDF burners and co-incinerated w/ MSW

Energy & revenue recovered via existingrecovered via existing HECO PPA

Option 2: Drying at Honouliuli WWTP w/ H-POWER Receiving

Ash would be removed and hauled as is current practice at H-POWER.

Footprint Considerations – Option 2

Thermal Drying

CHP

Thermal Drying Complex

Comparison of Options

Options and Sub Options Evaluated

Major ComponentsOptions

1a 1b 2a 2b 2c 2dMBU Cake Receiving X X X X X XRDF Cake Receiving X XThree indirect dryers (20 dtpd each) X X XThree indirect dryers (20 dtpd each) X X XTwo direct dryers (40 dtpd each) XHonouliuli Cake Storage X XHonouliuli Cake Receiving X X X XCHP 1,800 kW XCHP 500 kW XCHP 600 kW XAdditional Energy Recovery System X

2015-2040 Lifecycle Cost Analysis

2015-2040 Lifecycle Cost Analysis

Without CHP, Drying is the lowest costWith CHP, Drying is Still the LowestH‐Power Credit – Important for Dryer Economics!

Cake Hauling only Economical if Gas Beneficial Use is Maximized!

H-POWER Economics

The additional biosolids “fuel” will produce more electricity and $$$

• Receive all biosolids excluding SI WWTP (20-40 wtpd, Projections)• Dried biosolids HHV: 7,500 Btu/lb (Sampling Data)• Fuel electricity efficiency: 20% (ENV Refuse)• Fuel→electricity efficiency: 20% (ENV Refuse)• System uptime: 85% (ENV Refuse)• HECO PPA: $0.20/kW-hr, 81.5% to ENV Refuse (currently in place)

$• Tipping fee: $87.15/WT biosolids (ENV → Covanta)

~$1-2 MM/year additional from HECO → ENV Refuse

Cost Comparison

60

50

60lars

Option 1 ‐ No Drying + CHPOption 2 ‐ Drying + CHP

40

ions of d

oll

20

30

ost, in m

illi

10

20Co

0Capital Cost Capital + 25‐yr Operating Cost

But remember, Option 2 provides more capacity, redundancy

Option 2 Thermal Drying is Recommended

With t d i t H li li th i b k / tl t f• Without drying at Honouliuli, there is no backup process/outlet for Sand Island biosolids

• Drying opens up capacity at H-POWER that is not available for cake

• Co-incineration of dried biosolids at RDF tested successfully at H-

POWER

• Least cost option (significant reduction in operating cost)

• Potential future outlets

Option 1 Expanded Cake Receiving is Not Recommended

• Highly dependent on CHP electricity generation

• Insufficient cake receiving capacity at H-POWER

O h f k l lik l Other future cake outlets unlikely

• Co-incineration of cake at H-POWER

Recently implemented limited operating data Recently implemented, limited operating data

Maybe only available for MBU

• Cake storage is an odorous and labor intensive process

Option 2 Major Equipment Required

• Three indirect dryers (2+1) each sized for 20 dtpd

• Import cake receiving station

• Onsite cake conveyance

• Cake hopper (dryer feed)

Dried biosolids conveyance and silo• Dried biosolids conveyance and silo

• New building for dryers (demo existing Thermal Conditioning Bldg.)

• Digester gas cleaning equipment• Digester gas cleaning equipment

• Digester gas storage

• Auxiliary fuel tanku a y ue ta

Next Steps

• ENV/DDC proceed into planning, design, and construction

• H-POWER permit modifications

Discussion

Questions, comments, concerns…