Thermal Hydrolysis The Next Generation...Startup Methodology Fill all digesters ~60% with water Heat water to 100°F Continuous operation of HEX solids pumps for minimal mixing Transport

69th Annual KU Environmental Engineering Conference

Thermal Hydrolysis – The Next Generation

Dustin Craig, P.E.

Environmental Engineer CDM Smith

Matt Bond, P.E,

Chief Engineering Officer

KC Water


Agenda

Introduction to Thermal Hydrolysis (THP)

DC Water – 1st THP Installation

Startup Methodology

Seeding and Ramp Up

Commissioning Findings

KC Water – Blue River Biosolids Facility Project


Thermal Hydrolysis – Background and History

BEFORE AFTER

Thermal Hydrolysis (THP) is a process by which sludge is heated and pressurized with the purpose of reducing organic

solids to make them more readily biodegradable….

In other words, it’s a pressure cooker.


THP System Overview

To Dewatering

Thickened Primary Sludge

Screening Pre-Dewatering

Cake Storage

THPHEX

AnaerobicDigestion

Blending

ThickenedWAS


Why Consider THP?

▪ Increase Capacity and Improved Performance of Digesters

Without THP With THP

AnaerobicDigestion

AnaerobicDigestion

AnaerobicDigestion

AnaerobicDigestion

AnaerobicDigestion

AnaerobicDigestion

Typical Mesophilic Digester

THP Mesophilic Digester

5%-6% Feed Solids ~10% Feed Solids

~20 day SRT 12 – 15 day SRT

40% to 50% VSR (WAS/PS dependent)

60% to 65% VSR

Class B Biosolids Class A Biosolids


Why THP?

▪ Class A biosolids

▪ Increased downstream processing capacity

▪ Increased VSR and biogas▪ Projected 10–15% VSR

increase▪ Reduced digested solids

production▪ Potential energy neutrality

▪ Increased cake solids content▪ 10% increase

▪ Reduced digester foaming...and reduced odor

Without THP With THP


Best Fits for THP

▪ Digestion capacity expansion

▪ New digester implementation

▪ Excessive hauling costs

▪ Class B limitations on land application

▪ Elimination of landfill options

▪ Agricultural demand for class A biosolids

▪ High electrical cost areas


Digester Settling

1 minute 90 minutes 4 hours


Hydrolyzed Sludge Settling

1 minute 90 minutes 28 hours


Lower Odor of THP Biosolids Could Open Product Use Opportunities

25,000

15,000

10,000

5,000

0

20,000

Mea

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ead

spac

e D

etec

tio

n T

hre

sho

ld

(dilu

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to t

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THP with Centrifuge Dewatering

THP with BFP Dewatering

Conventional MAD with Centrifuge

THERMAL HYDROLYSIS PROCESSES CONVENTIONAL MESOPHILIC

Source: Murthy, 2012


THP Background - History▪ First full scale THP system commissioned in

1995 by Cambi

▪ HIAS plant Lillehammer, Norway

▪ Original vessels are still in operation

▪ Kruger/Veolia 1st pilot plant 2004 (Biothelys) full scale ~2009.

▪ Kruger/Veolia 1st Exelys plant 2014

▪ First US Installation – DC Water Operational October 2014 (Cambi)

▪ 8 US THP Facilities in planning/design/construction


THP Background - Manufacturers

▪ Cambi ~50 facilities. 1 operating in US. 8 Additional in US in next 3 years.

▪ Veolia/Kruger 2 types

▪ Biothelys – continuous batch ~7 facilities + 1 US pilot

▪ Exelys – continuous 2 facilities + 1 demonstration

▪ Sustec – 2 full scale, 3 pilot

▪ Haarslev – 2 pilot scale plants


DC Water: First Operating THP Facility in North America


Background

2.2 million water and

wastewater customers in DC

Annual operating budget $300M+

$3.8B 10 Year

CIP

1,100 employees

8-Time Winner

of National Association of Clean Water

Agencies Gold Peak

Performance Award

DC Water is the largest

power user in Washington,

DC

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=8LCpoYI_cf-r0M&tbnid=jDF_zAgpCBvyzM:&ved=0CAUQjRw&url=http://www.njcharters.com/nj_charters_blog/2011/04/2669.html&ei=25wdUc_IL-rgiAKejYFY&bvm=bv.42553238,d.cGE&psig=AFQjCNEYULKsYYxRwtAQTwIKIyP7J9ToTA&ust=1360981583406418


Overview of Blue Plains AWTP

▪ 391 mgd average day capacity

▪ ~160 acres

▪ Largest Advanced WWTP in the world

▪ Serves DC, plus areas of Maryland and N. Virginia

▪ Advanced secondary treatment – filtration, N and P removal

▪ Discharge to Potomac


Main Process Train Project

Solids Blending Tanks

Sludge Screening

Pre-Dewatering

Dewatered Sludge Storage and Pumping

Thermal Hydrolysis (Cambi)

Sludge Cooling

Digestion

Digested Sludge Transfer & Holding


DC Water – Case Study

▪ Implemented THP/Digestion with Seeding beginning in October 2014

▪ Full throughput in February 2015

▪ Full acclimatization in late 2015

▪ Temporary Approval for Class B Land Application February 2015

▪ Approval for Class A Land Application May 2016


Commissioning Objectives

▪ Initiate seeding of digesters with Class A biosolids

▪ Maintain solids throughput (estimated at 300 dtpd at start of commissioning)

▪ Continue Class B land application until Class A achieved and approved


Startup Methodology▪ Fill all digesters ~60% with water

▪ Heat water to 100°F

▪ Continuous operation of HEX solids pumps for minimal mixing

▪ Transport sludge and fill remaining volume of two digesters with class A seed sludge (~1% solids in each digester)

▪ Continue heating digester with steam

▪ Begin mixing with draft tube mixers (startup mixers over 12 hour period)

▪ Begin feeding TH solids to first digester (overflow to adjacent digester)

▪ Ramp up solids based on VS in digesters


Daily Feed Rates

0

50

100

150

200

250

300

350

400

450

Soli

ds

Thro

ugh

pu

t, d

tpd

Digester 1 Digester 2 Digester 3 Digester 4 Total

Average Mass Feed Rate = 303 dtpdAverage SRT = 21 days


Seeding and Ramp Up Results

▪ First digester lower solids concentration▪ Initial sludge provided was more dilute

▪ Steam added water to digester

▪ Maintaining temperature required significant steam

▪ Initial decline of pH and Alkalinity▪ Added alkalinity to first 2 digesters

▪ Rapid increase in alkalinity after two weeks


Solids Concentration in Digesters

0

1

2

3

4

5

6

7

8

Per

cen

t To

tal S

oli

ds

Date

Digester 1 Digester 2 Digester 3 Digester 4


Volatile Solids Reduction

0

20

40

60

80

100

50

60

70

80

90

100

Per

cen

t V

ola

tile

So

lid

s R

edu

ctio

n

Per

cen

t V

ola

tile

So

lid

s

Date

Pre-Digestion Screened Blended Solids Final Thermal Hydrolysis & Digested Belt Filter Press Cake Volatile Solids Reduction

Average Feed VS = 81%Average VSR = 68.5%


Fecal Coliform Results (Dewatered Biosolids) During Commissioning


Meeting and Exceeding Class A Requirements –Long Term Operation

0

10

20

30

40

50

60

70

80

Feca

l Co

lifo

rm M

PN

/gra

m

Date

Final Thermal Hydrolysis & Digested Belt Filter Press Cake

Average Fecal Coliform <5 MPN/gramMax Fecal Coliform 72 MPN/gram


Dewatered Solids Concentration – Long Term Operations

20

25

30

35

40

Per

cen

t To

tal S

oli

ds

Date

Final Thermal Hydrolysis & Digested Belt Filter Press Cake

Dewatered solids ~32%Polymer use ~20 to 22 lbs/ton


Findings - Commissioning▪ Supplemental Heat Required

▪ Ramp up conservatively (max. 5% per day increase feed)

▪ Supplemental alkalinity allows faster ramp up (initial drop in pH)

▪ Digested solids not Class A for ~150 days (acclimatization)

▪ High VSR (60%+)

▪ Methane Concentrations 62%+▪ Reduced concentration is early sign of upset

▪ Ammonia elevated

▪ Rapid increases in feed can cause upset


Findings - Operating Issues

▪ Mechanical Issues▪ Rotary Lobe Pumps▪ Cake Bin Gates▪ Centrifuge Solids Control▪ Wear on Mechanical Equipment

▪ Process Issues▪ Vivianite▪ Grit▪ Foam▪ Odors

▪ Support Equipment Issues▪ Steam Pressure▪ Flare Exhaust Results▪ Dilution Control


Findings - Current Operations

▪ THP Temperature reduced caused excessive foam in digesters

▪ Use of plant effluent caused microbially induced corrosion (MIC) in heat exchangers

▪ Annual inspection of pressure vessels indicated high wear of steam nozzles due to grit

▪ Rapid changes in feed have resulted in foaming events

▪ Centrifuges require most operator attention of all components

KC WATERBlue River Biosolids Facility Project

M a t t B o n dC h i e f E n g i n e e r i n g O f f i c e r

A p r i l 2 0 1 9

• Combined water, wastewater, and

stormwater utility

• $409M Enterprise (FY19)

• 860+ Employees

• 470,000 residents served inside the city;

200,000 residents outside the city

• Over 2,800 miles of water mains and 2,800

miles of sewer mains in Kansas City across

318 square miles.

• Produces an average of 94 MGD

Over vi ew of KC WaterLar ge Ser vi ce Ar ea -Re l a t i ve ly Smal l Popul a t i on

KC 14% of Combined

Population of San Francisco,

Miami,

Philadelphia and

Boston

Blue River WWTP

Birmingham WWTP

Westside WWTP

COST

• Costly incinerator upgrades

• Air emissions challenges

• Landfills not available, no longer a viable option

• Class A product for beneficial reuse

DETERMINING THE NEED

32

33

OPTIONS CONSIDERED

Multi-Hearth Furnace

Photo Credit: Shaun O’Kelley , Blue River WWTP

Thermal Hydrolysis

Photo Source: Wikimedia, THP -https://commons.wikimedia.org/w/index.php?curid=50970357

Lime StabilizationPhoto Source: www.irishwaste.net/service/industrial-services/mobile-lime-stabilisation-plants/

Fluidized BedPhoto Source: Kuzu Grup, Fluid Bed -http://www.kuzugrup.com/en/proje/buski-fluidized-bed-sludge-

incineration-and-energy-production-plant/

34

QUADRUPLE BOTTOM LINE

Positive Impacts of Thermal Hydrolysis on Digester Biology, Rheology, Capacity and Up/Downstream Processes

Increase Digester Capacity• > 2 times the loading of conventional

digestion

• Reduced tankage install

Hygienization• Class A sterilization

• Makes mesophilic digestion more

robust

Thermal

Hydrolysis

Mesophilic

Anaerobic

Digestion

“Pressure

Cook”

20 minutes at

320 oF

Rheological Properties• Reduced viscosity (easier to pump)

• 10 percent sludge readily flows

• Reduced pumping and mixing

requirementsBiosolids Characteristics• >30 percent TS cake typical

• Stackable cake

• Low odor product

Biogas Production• Increased yield

• Higher methane content in gas

BENEFITS

36

Elimination of

incineration and

emissions

All solids

processed

through existing

digesters

Class A product,

beneficial use of

biosolids

Energy recovery Odor reduction

Proposed THP System

THP Units

Primary Sludge

PS Screens

East Sludge

Holding Tank

CentrifugesPre-dewatering

Polymer Feed System

THP Feed Tank

Thickened WAS

Existing Systems

New Process

To Land Application

or Landfill

Storage and Loadout

On-site Boiler/

Steam Generator

Combined Heat Power (future)

Biogas Cleaning

Anaerobic DigestersHeat Exchanger West Sludge

Holding Tank

Centrifuges

Polymer Feed System

Not Shown: Odor

Control, FOG, and

Sidestream Management Systems

Post-dewatering

Bioso lids Fac ilit y Conceptual Design

39

DRIVING INNOVATIONS

• Risk Management

• Collaborative Project Delivery (Design/Build)

• Building Information Model (BIM)

• Approved Financing• Water Infrastructure Financing

and Innovations Act (WIFIA) - 2018

• Clean Water State Revolving Fund (SRF)

Defin ing KC W ater ’s BIM Program

• 3D based design

• Automated interference detection

• Design and constructability reviews

• Contractor schedule/budget management, phasing scenarios

• Whole-life asset management

• Defined protocols for future BIM

40

Design

ReviewClash

Detection Analysis

Drawings &

Schedules

Visualization

SpecificationsScheduling

Cost

Estimating

SCHEDULE

41

COMPLETE PRELIMINARY

DESIGN

ISSUE RFQ

LATE SUMMER

2019

SHORTLIST

ISSUE RFP

FALL 2019

EVALUATE PROPOSALS

WINTER 2019

DESIGN/BUILDER

NOTICE TO PROCEED

SUMMER 2020

KC WATERBlue River Biosolids Facility Project

M a t t B o n dC h i e f E n g i n e e r i n g O f f i c e rm a t t . b o n d @ k c m o . o r g 8 1 6 - 5 1 3 - 0 1 6 8

A p r i l 2 0 1 9

mailto:[email protected]


Discussion & Questions…

Dustin Craig, PE

Environmental Engineer

816.877.4802 [email protected]

Matt Bond, PE, WEF Fellow

Chief Engineering Officer

816.513.0168

[email protected]



Documents

Thermal Hydrolysis The Next Generation...Startup Methodology Fill all digesters ~60% with water Heat water to 100°F Continuous operation of HEX solids pumps for minimal mixing Transport