TurboTec® Pilot tests

WWTP Amersfoort

31-5-2011

Content

• TurboTec® thermal sludge hydrolysis

• Test set up

• TurboTec® test Amersfoort sludge

• TurboTec® test Geestmerambacht sludge

• Summary of results

Continuous thermal hydrolysis: TurboTec®

Exocellular substances

Cells

140°C

Intracellular substances 6 bar

Stabilized sludge flocs pretreated sludge

Figure 1: Effect of thermal hydrolysis

Waste activated sludge contains a lot of EPS, which has a negative

Goals:- More biogas- Shorter retention time for digestion- Decreased viscosity- Increased dewaterablitiy

TurboTec pilotlot of EPS, which has a negative influence on digestability and dewatering of the sludge. By thermal hydrolysis the EPS is broken down

3

TurboTec® pilot plant

Pilot set up TurboTec® Digesters

Thickening

Fluidized sludge Water lock

Reject water

before and after

TurboTec®4

Test set up

On WWTP Amersfoort tests have been done with sludge from WWTP

Amersfoort and WWTP Geestmerambacht.

WWTP Amersfoort :low loaded carrousel with primary settling

Geestmerambacht :low loaded carrousel without primary settling

The TurboTec® test are performed in the period September 2010 till June 2011

Amersfoort sludge• Thermal hydrolysis on waste activated sludge and digestion of hydrolysed• Thermal hydrolysis on waste activated sludge and digestion of hydrolysed

waste activated sludge combined with primary sludge

• Decreasing retention time in digester

Geestmerambacht sludge• Thermal hydrolysis on waste activated sludge and digestion

• Increasing TS of waste activated sludge from 6% TS till 12%TS

Primary sludge 6 %

Secundary sludge 6 %

Digestion REF

RT 20 dDe-

watering

Primary sludge 6 %

Secundary sludge 6 %

Digestiong TT

RT 20 dDe-

wateringTH TT

Test 1a

Test 1b

Sludge WWTP Amersfoort

Primary sludge 6 %

Secundary sludge 6 %

Digestion REF

RT 20 dDe-

watering

Primary sludge 6 %

Secundary sludge 6%

Digestion TT

RT 20 -> 12 dDe-

wateringTH TT

Test 1b

TH TT = thermal hydrolysis TurboTec® Digestion REF = reference digester

Digestion TT = TurboTec® digester

Waste activated

sludge 6 %

Digestion REF

RT 20 dDe-

watering

Waste activated

sludge 6 %

Digestion TT

RT 20 dDe-

watering

TH

TT

Test 2aSludge WWTP Geestmerambacht

Digestion REF

RT 20 dDe-

watering

Waste activated

sludge12 %

Digestion TT

RT 20 dDe-

watering

TH

TT

Test 2b

Waste activated

sludge 6 %

Analyses

• TS- balances

• COD-balances

• Biogas production

• Biogas composition

• P-balances• P-balances

• N-balances

• Dewaterability

• Reject water composition

• Heavy metal balances

• Viscosity analyses

Technical fuctioning

In general the pilot performed well:

• No scaling in the TurboTec® unit

• Digesters operated continuously

During the test there have been some technical problems:

• Blockage in the digesters (test 2a/b), which resulted in mixing problems

in the digester

• Problems with pumps (especially recirculation pump TurboTec® - in full • Problems with pumps (especially recirculation pump TurboTec - in full

scale this pump will be replaced by a mixer)

• Problems with heating/cooling system of the digesters – causing

high/low temperatures

ConclusionMost technical problems occurred in the digesters

There were very few problems with the TurboTec® thermal hydrolysis

Most problems can be explained by typical small pilot scale

Effects of thermal hydrolysis on Amersfoort sludge

Process parameter TT REF TT/REF

Average TS removal(%) 2,14 1,84 1,16

Biogas production (L/h) 113 96 1,18

COD(total) to methane(%) 40,1 36,2 1,11

COD(total) after digestion (%) 40,4 48,8 0,83

Sludge cake TS(%) on lab scale centrifuge 18,0 14,6 1,23

Sludge cake TS (%) on pilot centrifuge 22 18 1,22

Effects of thermal hydrolysis (TT/REF) on the total sludge (primary + secundary)

Sludge cake TS (%) on pilot centrifuge 22 18 1,22

N in reject water (g/L) 1,64 1,47 1,12

P in reject water (g/L) 0,19 0,20 0,95

Effects of thermal hydrolysis (TT/REF) op the secundary slib

Process parameter Before After TT/REF

Specific biogas production (L/kgTS) 231 311 1,35

Viscosity secundary sludge at 100 rpm (mPas) 878 129 0,15

Reducing retention time Amersfoort sludge

50,0

100,0

150,0

200,0

250,0B

iog

as

pro

du

cti

e (

L/h

)

Biogasproductie vergisters fase 2

RT 20 d

RT 16 dRT 14 d RT 12 d

RT 20 d RT 20 d

Factor 1,18

Factor 1,18*20d/12d = 1,97

0,0

27-dec 3-jan 10-jan 17-jan 24-jan 31-jan

datum

Vergister TT Vergister REF prognose TT prognose REF

Problems with

heating REF

digester

By means of thermal hydrolysis the retention time can be reduced till 12 days

without losing gas production.

Factor 1,18

Feeding TS Geestmerambacht

4

6

8

10

12

DS

(%

)

DS gehaltes spuislib Geestmerambacht

Feeding of TT and REF digesters:

• from 1st of February till 29th of March both digesters have been fed

with 6% TS

• after 29th of March the TT digester is fed with 12% TS and REF digester

with 6% TS.

0

2

1-feb 15-feb 1-mrt 15-mrt 29-mrt 12-apr 26-apr 10-mei 24-mei

datum

sec. ruw Sec. na rotor Sec. na trommel sec. na tril Sec. na centri

Effect of thermal hydrolysis on 6% TS Geestmerambacht waste activated sludge

Process parameter TT REF TT/REF

Average TS removal(%) 1,93 1,49 1,30

Specific biogasproduction (l/kg TS) 335 272 1,23

Slibcake TS (%) with pilot centrifuge 25 18 1,38

N in rejectwater (g/L) 1,95 1,67 1,17

Effects of thermal hydrolysis on Geestmerambacht sludge

P in reject water (g/L) 0,21 0,20 1,05

Biogasproduction sludge Geestmerambacht

The TS of the feeding of the TT digester is doubled by pre-dewatering the

sludge with a centrifuge. This results in a double biogas production.

150,0

200,0

250,0

Bio

ga

s p

rod

uc

tie

(L

/h)

Biogasproductie vergisters Geestmerambacht

0,0

50,0

100,0

150,0

1-feb 15-feb 1-mrt 15-mrt 29-mrt 12-apr 26-apr 10-mei

Bio

ga

s p

rod

uc

tie

(L

/h)

datum

TT Vergister REF Vergister

Viscosity

Conclusion:

viscosity of TT sludge 12% TS = viscosity of normal sludge 6 % TS

Due to decreased viscosity digesters can be fed with a high TS content up to 12%.

Summary of the results

TurboTec® thermal hydrolysis has the following effects on secundary waste

activated sludge:

� Increased biogasproduction and DTS reduction by factor 1,30

� Increased TS of dewatered sludge cake by factor 1,35

� Reduced retention time for digstion down to 12 days

� Reduced viscosity by factor 7

� Digester feeding up to 12% TS