Quantifying the power of in-sewer treatment

Quantifying the power of in-sewer treatment

Tim Evans*, Maria Sandell**, Per Andersson** and Åsa Wievegg**

* TIM EVANS ENVIRONMENT, Stonecroft, Park Lane, Ashtead, KT21 1EU, UK [email protected]

** Surahammars KommunalTeknik AB, Box 10, 735 21 Surahammar, Sweden

SPN7 20137th International Conference on Sewer Processes & Networks, 28 - 30 August 2013, Sheffield

T IM EVANSE N V I R O N M E N T


Proposition• In 1997 Surahammar offered citizens

food waste disposers as an option• By 2008 50% of households used them

– Number of citizens and households had not changed• The amount of biodegradable matter discharged to sewer

must have increased• WwTW influent monitored systematically:

– 24-hour composite samples taken 4-weekly• Mass balance of what went in compared with what arrived

at WwTW must be what bio-transformed in the sewers [if it didn’t settle out]– Jonathan Mattsson and Annelie Hedström are the latest, and most comprehensive, to

show it does not settle

Surahammar: founded 16th and 17th centuries based on iron. Birthplace of Swedish car industry (1897) Topography: gently rollingApprox 10100 people living in 3700 householdsSewers separate with interconnection weirs – sewers laid at 0.004-0.005; Haga WwTW: primary settlement – activated sludge – mesophilic anaerobic digestion – sludge to drying beds – Miscanthus grass – topsoil manufacture

≈ 7100 people

≈ 1500 people

≈ 1500 people

Haga WwTW


Surahammar Kommunal Teknik AB (SKT)

• 1993 pre-study of FWD– 32 apartments with FWD + 7 without– sewers - no effect; residents - 96% satisfied; water consumption

25% less[?]; refuse 4.8m3 to 1.2m3 /week

• 1997 launched new waste charges– Home composting = £0– 8-year lease FWD from SKT = £27/year– Kerbside separate collection = £209/year– Central drop-off bins for card, paper, plastic, glass, metal– By 1998 30% of households (1110) were leasing FWD

– By 2008 50% of households (1850) were leasing FWD

– Total waste to landfill 1996 = 3600t - in 2007 = 1400t

3mm screens Grit settlement

Primary treatment/settlement

Final settlement/clarification

Secondary [biological] treatment [of ‘settled sewage’]

Sludge digestion

‘return’ or ‘surplus’ activated sludge or ‘humus’ sludge in the case of biological filters

Reclaimed water

Screenings and grit to disposal

Storm tanks(to balance excess flow)

Influent sample point24 hour composite

4-weekly 92% on Wednesdays

Samples analysed used Swedish Standards methods


What are FWD inputting?Kegebein, J.; Hoffmann, E. and Hahn, H.H. (2001) Co-Transport and Co-Reuse, An Alternative to Separate Bio-Waste Collection? Wasser. Abwasser 142, 429-434

• 15% - 36% “dissolved”• 98% <2mm• 100% <5mm• Sediment-free transport at 0.1m/sec

Sieve analysis – 2 samplesSettling velocity m/h


Estimates of the contributions made by FWD to wastewater composition based on laboratory studies

COD BOD Ntot NH4-N Ptot SS g/person.day Bolzonella et al. (2003) 1 75 2.5 0.25 50 de Koning and van der Graaf (1996) 2 76 52 1.6 48

de Koning (2004) [whole wastewater] 3 95 66 2.1

0.3 60 NILIM (2005) 4 11.3 0.73 0.11 8.2 Rosenwinkel and Wendler (2001) 5 27 10.5 1.5 0.19 34

Thomas (2011) 6 35.8 16.5 0.03 0.11 14.1 Tidåker et al. (2005) 5 48 17.2 0.81 0.09 0.14 33.4 Wainberg et al (2000) 5 52.6 1.0 0.2 19.0 mean 58.5 28.9 1.5 0.1 0.2 33.3 median 52.6 16.9 1.5 0.1 0.2 33.7 standard deviation 24.4 23.9 0.7 0.0 0.1 18.6

de Koning (2004) [settled sewage] 67 53 2 0.27 6

Footnotes 1. Cafeteria waste both food prep waste and plate waste and 2 different FWD 2. calculated from C445H736O221N27S 3. Additional loads of pollutants due to the use of FWD estimated from other studies [Nilsson et al. 1990,

van Nieuwehuijzen 2002, de Koning 2003] 4. Based on an assumed 99g food waste /person.day, which was derived from FWD installed in 301

domestic properties and one hotel. 5. Averages of a summary of the literature and the authors' own laboratory data 6. Based on 142g food waste which was the average collected by each volunteer


Estimates of the effect of FWD based on samples taken from sewers, from pumping stations or from a WwTW

Authors Description COD BOD Ntot NH4-N Ptot SS g/person.day Battistoni et al. (2007) 1

96 days pre FWD 125 13 10 2 37 179 days with 67% FWD 180 15 10 1 49 Δ 55 2 1 -1 11

Boyle (1985) 2

Maple Bluff 60 69 Shorewood Hills 54 63 EPA Design Manual 63 70 Δ -6 -4

Evans et al. (2010) 3

840 days pre FWD 107 40 11 7 2 840 days with 50% FWD 88 33 11 7 1 Δ -19 -8 -1 0 -1

Meins (2005) 4 blackwater 117 60 7 4.4 1.3 13.6

Nilsson et al. (1990) 5

pre FWD total 155 40 8.7 3.9 80 pre FWD dissolved 42 14.5 7.9 1.5 with FWD total 243 71 10.2 3.1 114 with FWD dissolved 56 25.4 7.9 2.1 Δ total 88 31 1.5 -0.8 34 Δ dissolved 14 10.9 0 0.6

NY DEP (1999) 6

control, no FWD 75.84 26.40 8.94 4.13 1.27 29.66 FWD 121.56 59.15 14.06 5.90 1.77 50.89 Δ 45.72 32.75 5.13 1.77 0.50 21.23

Footnotes 1. sampled at WwTW 2. [terminal] PS from these suburb 'villages' sampled for 9 years. FWD installation at Maple Bluff increased from 40%

to 90%. Shorewoord HIlls was 100% FWD 3. sampled at WwTW as 4-weekly 24-h composite samples for 10100 population 50% of whom used FWD 4. toilet water + FWD Skogaberg (Gothenburg) 133 households sampled at a manhole close to the buildings 5. sampled at a manhole where drains from several buildings connected 6. sewage sampled from manholes for apartment buildings with FWD (adjusted to 100%FWD) compared with no FWD.

Brooklyn excluded because of contamination.

Greatest difference closest to kitchens

and least difference furthest from kitchens and longest time for acclimation


Daily flow of influent (m3/day) measured after 3mm screens and grit settlement at the time of 4 weekly sample collection ‑

1000

3500

6000

8500

11000

13500

Dai

ly in

com

ing

flow

m3 /

day

(log1

0 sc

ale)

FW

D

inst

alla

tion

star

ted

sta

rte

d

data point for 10 January 2001, 19813 m3/day omitted


BOD7 loading (kgBOD7/day) - 4 weekly 24-hour composites

0

100

200

300

400

500

600

700

800

900

Influ

ent B

OD 7

load

kg/

day

FW

D in

stal

lati

on s

tart

ed

extreme data points omitted: 16/10/96 1117 kgBOD/d; 08/03/00 1166 kgBOD/d; 10/01/01 1446 kgBOD/d

300

350

400

450

500

550

1995 1997 1999 2001 2003 2005 2007 2009

Ave

rage

ann

ual

biog

as m

3 /da

y

FW

D in

stal

latio

n st

arte

d

Average annual biogas (m3/day) [1995, 1996, 1997 and 1998 are from Karlberg & Norin, 1999]

Mea

n 33

1

Mea

n 41

0

Mea

n 48

4


Student's t-test comparing influent and biogas pre and post FWD installation (from Evans et al., 2010)

Flow m3/d kgBOD7/d kgCOD/d kgN/d kgNH4/d kgP/d BOD7:N m3 biogas/d

Mean 0% FWD

120 weeks 11/01/95-30/04/97 4706 408 1084 113.6 74.0 18.0 3.50 331

Variance 3034123 46620 394192 979 405 49.9 1.695 1036

Mean early post FWD

120 weeks 12/01/99-02/05/01 5194 520 1420 113.8 62.4 17.5 4.60 410

Variance 13156275 69225 425475 1507 391 22.4 2.341 6.937

Difference (early post120 - pre) +10.3% +27.4% +31.0% +0.16% -15.7% -2.6% +31.5% +23.9%

P (1-tail T-test) 0.25 0.04 0.03 0.49 0.02 0.39 0.002 0.03

Mean 50% FWD

120 weeks 13/12/06-01/04/09 4678 331 892 107 71 13.3 3.11 484

Variance 5675190 17138 167426 548 282 12.7 1.191 3147

Difference (50%-0%) -0.59% -19.0% -17.7% -6.1% -3.9% -26.1% -11.1% +46%

P (1-tail T-test) 0.50 0.06 0.09 0.18 0.28 0.002 0.11 0.01

Analytical suite did not include SS unfortunately


Estimates of the effect of FWD based on samples taken from sewers, from pumping stations or from a WwTW

Authors Description COD BOD Ntot NH4-N Ptot SS g/person.day Battistoni et al. (2007) 1

96 days pre FWD 125 13 10 2 37 179 days with 67% FWD 180 15 10 1 49 Δ 55 2 1 -1 11

Boyle (1985) 2

Maple Bluff 60 69 Shorewood Hills 54 63 EPA Design Manual 63 70 Δ -6 -4

Evans et al. (2010) 3

840 days pre FWD 107 40 11 7 2 840 days with 50% FWD 88 33 11 7 1 Δ -19 -8 -1 0 -1

Meins (2005) 4 blackwater 117 60 7 4.4 1.3 13.6

Nilsson et al. (1990) 5

pre FWD total 155 40 8.7 3.9 80 pre FWD dissolved 42 14.5 7.9 1.5 with FWD total 243 71 10.2 3.1 114 with FWD dissolved 56 25.4 7.9 2.1 Δ total 88 31 1.5 -0.8 34 Δ dissolved 14 10.9 0 0.6

NY DEP (1999) 6

control, no FWD 75.84 26.40 8.94 4.13 1.27 29.66 FWD 121.56 59.15 14.06 5.90 1.77 50.89 Δ 45.72 32.75 5.13 1.77 0.50 21.23

Footnotes 1. sampled at WwTW 2. [terminal] PS from these suburb 'villages' sampled for 9 years. FWD installation at Maple Bluff increased from 40%

to 90%. Shorewoord HIlls was 100% FWD 3. sampled at WwTW as 4-weekly 24-h composite samples for 10100 population 50% of whom used FWD 4. toilet water + FWD Skogaberg (Gothenburg) 133 households sampled at a manhole close to the buildings 5. sampled at a manhole where drains from several buildings connected 6. sewage sampled from manholes for apartment buildings with FWD (adjusted to 100%FWD) compared with no FWD.

Brooklyn excluded because of contamination.

BOD:N4.61.87.03.2


Conclusions• We know 50% of households use FWD to divert kitchen

food waste to sewer• Surahammar+Ramnäs discharges to Haga ≈ 8600 people• Extra input from averages of lab studies x 8600 x 50%

124 kg BOD/d; 251 kg COD/d and 6.5 kg N/d• Influent monitoring at Haga 0% FWD minus 50% FWD

-67 kg BOD/d (P 0.06); -192 kg COD/d (P 0.09) and -7 kg N/d (P 0.18)

• Mass balance: sewer biofilms bio-transformed191 kg BOD/d; 443 kg COD/d and 13.5 kg N/d44 g BOD/cap.d; 103 gCOD/cap.d and 3.1 gN/cap.d for each person in a FWD household

• Has biofilm ecology [email protected]

Quantifying the power of in-sewer treatment

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