enhancement of methane productivity of anaerobic reactors of wasterwater treatment plants aare...

Enhancement of Methane Productivity of Anaerobic Reactors of Wasterwater

Treatment PlantsAare Kuusik, E. Loigu, O. Sokk, Argo Kuusik

Estonia

Objectives of Experiments:

Enhancement of methane productivity of existing anaerobic reactors

To get rid of inconvenient waste solids: waste glycerol and fishery residues

To resolve above problems in one process

Self-made Reactor

Self-made Reactors

Manufactored ReactorsArmfield W8

Technological Scheme of Self-made Reactor

Technological Scheme of Manufactured Reactor

Maintenance of Reactors

• Mesophilic temperature 36-39 oC, mainly 37-38 oC

• Batch type or fill and draw input-output of sludge every morning

• Before and after the input-output process the contents of the reactors were mixed

• Produced biogas was evaluated

Concentrations were measured

• Every morning: pH, H2S, NH3, CO2, O2

• Once a week: TS and VS, VFA and alkalinity

of input and output sludge

The data of the single sludge digestion was summarised

Days consi-dered

Reten-tion ti-

me, days

Volume load TS kg/m3

Input, g/L

Output, g/L

Organic removal input-output,

g/LTS VS TS VS ∆TS ∆VS

9 -21 40 0.885 35.4 26.625 22.375 14.05 13.025 12.62522 - 30 35 1.011 35.394 26.62 22.159 13.234 13.234 1338.831 – 41 30 1.088 32.644 24.169 22.331 13.819 10.313 10.3542 – 55 25 1.048 26.203 16.25        56 - 82 20 1.601 32.025 22.375 21.863 13.713 10.163 8.663

Average   1.227 31.972 22.693 22.1 13.728 11.242 10.504

Continuation of previous table (single sludge)

Retention time, days

Tempe-ratureoC

Methane yield Methane contents in biogas

%

Solid removal %

Per volume

L/m3

TS removed

L/∆kg

∆TS ∆VS

40 36,5 109.7 339.6 50.98 36.51 47.23

35 37,4 82.1 217.1 51.84 37.40 50.25

30 36,4 92.9 270.3 52.16 31.59 42.81

25 38,5 117.9   54.51    

20 37,9 171.5 337.24 57.59 31.75 38.68

Average 37.2 128 310.9 54.39 33.55 42.95

Admixed sludge (sludge 98% + 2% waste glycerol) digestion

Days consi-dered

Reten-tion time, days

Volum load, TS

kg/m3/d

Input, g/L Output, g/L Difference between input-

output, g/LTS VS TS VS ∆TS ∆VS

12 – 19 40 1.315 52.575 42.375 23.0 14.525 29.575 27.8520 – 39 35 1.458 51.034 40.994 23.166 14.328 27.869 26.66640 – 63 30 2.567 44.925 34.613 23.269 10.448 21.656 24.16964 – 75 25 2.110 52.75 41.125 30.672 17.891 22.078 23.23476 – 80 20 2.497 49.938 38.213 24.543 9.536 25.4 16.175Averag

e  2.016 49.307 38.756 24.588 13.274 24.720 24.578

Continuation previous table (sludge 98% + glycerol 2%)

Reten-tion time,

days

Tempe-rature

oC

Methane yield Methane contents

in biogas, %

Solid removal %

Per reac-tor volu-me, L/m3

Per TS removed,

L/∆kg

∆TS ∆VS

40 37 336.7 483.5 62.71 56.3 65,72

35 37 268.8 352.8 61.17 54.62 65,06

30 39.3 287.3 356.6 61.81 48.19 69,82

25 36.5 386.8 416.3 60.05 41.85 56,49

20 37.9 536.7 374.2 61.75 50.85 75,06

Average 37.8 323 381.9 61.42 50.1 66

The weighted means of experimentsSubs-trate

Days consi-dered

Retention time,days

TS input,g/L

VS input,

g/L

TS output,

g/L

VS output,

g/L

∆TS,g/L

∆VS,g/L

Sludge 100%

73 27.6 32.0

(26.2-35.4)

22.7

(16.3-26.6)

22.1

(21.9-22.4)

13.7 (13.2-14.1)

11.2

(10.2-13.2)

10.5 (8.7-13.4)

Sludge 98% + glycerol

2%

69 31.0 49.3 (44.9-52.8)

38.8 (34.6-42.4)

24.6 (23.0-30.7)

13.3 (9.5-17.9)

24.7 (21.7-29.6)

24.6 (16.2-27.9)

Sludge 95% + glycerol

5%

70 35 64.0 (58.2-77.3)

58.6

(48.8-64.1)

27.0 (23.5-32.3)

15.1

(10.8-19.0)

44.5

(34.4-53.8)

43.7

(38.0-50.7)

Sludge 98% + fish 2%

29 35.7 43.0 (40.4-46.8)

32.4 (30.2-34.8)

23.8 (21.5-24.6)

14.0

(12.8-15.0)

20.8 (18.9-22.6)

18.4 (17.4-19.9)

Continuation of weighted means tableSubstrate Methane yield Methane

contents in biogas %

Solid removal %

Per volume ,L/

m3

Per remo-ved TS, L/∆kg

∆TS ∆VS

Sludge 100%

128 (82-172) 310.9 (217-340)

54. (51-57.6) 33.6(31.6-37.4)

43(38.7-50.3)

Sludge 98% +2% glyc.

323(269-537)

381.9(338-455)

61.4(60.1-62.7)

50.1(41.9-56.3)

66(65.1-75.1)

Sludge 95% + 5% glyc.

488.6(234.9-705.3)

386.1(273.1-530.4)

59.3(57-61.6)

62(54.7-69.6)

74.3(68.1-77.9)

Sludge 98% +2% fish

369.4(328.9-419.5)

627.7(582.6-686.2)

63.5(62.4-64.9)

48.5(46.7-50.7)

56.8(55.8-57.7)

Percentage comparison of essential weighted means (in brackets)

Substrate Retention time in days

Percentage relations

TS load per reactor volume

(kg/m3)

Solids residue after

treatment(g/L)

CH4 produc.

per reactor volume, (L/m3)

Raw sludge 100%

40 - 20 100 (1,227) 100 (22.1) 100 (128)

Sludge 98%+ glycerol 2%

40 - 20 164 (2.016) 111.3(24.588) 252 (323)

Sludge 95% + 5% glycerol

40 – 20 173.1(2.124) 122.1(26.994) 382 (488.6)

Sludge 98% + fish resid. 2%

40 - 30 99 (1.215) 107.9(23.836) 288.6(369.4)

THANK YOU FOR YOUR ATTENTION