Hydrogen Sulphide gas (H2S)and

Spent Mushroom Compost (SMC)

TeagascMushroom Group

Spent Mushroom Compost

Waste product 3-4,000 tonnes weekly Good agricultural value:

– Slow release N & P– Soil improver

But…– Costly to transport– Only required seasonally– Must be stored

Storage & Disposal

Stored over Winter andduring Summer

Traditionally spread onland in Spring andAutumn

Agricultural contractors Local farmers Can be a problem in

Monaghan/Cavan area

Nitrates Directive

Rate of SMC use onland is reduced to:

– 12-24 tonnes / ha

Very small relative to“previous” use:

– 50 tonnes + / ha

May lead to– disposal problems– Increased storage times

Nitrates directive

SMC is an organic wasteMust be stored

– on concrete pad with holding tank for runnoff– Undercover / shed

Closed winter period for land spreading of13-15 weeks

Hydrogen sulphide gas (H2S)

Recent fatality in 2005 Health and Safety issue Increased awareness H&S guidelines to

industry

Current HSA guidelines

9.4. Storage and handling of spent mushroom compostMUSHROOM compost stored in large heaps, especially when not turned foraeration, produces dangerous levels of hydrogen sulphide gas in the interior ofthe heap. Precautions when handling this material include:

Never handle the spent mushroom compost in an enclosed space, such assheds, tanks or trailers, where the toxic gas can build up. Make sure that thereis good thorough ventilation when moving compost.

Children should not have access to stored spent mushroom compost andshould be kept off site during any handling or removal.

Only handle compost on a windy day when there is good air movement andkeep persons not directly involved in the work well away from the work area.

Persons using machinery to move spent mushroom compost should keep cabdoors and windows closed and a Hydrogen Sulphide monitor should be usedinside the cab.

If it’s possible that hydrogen sulphide is present, as indicated by the smell ofrotten eggs, certified freshair breathing apparatus should be used, in addition tothe controls listed previously.

Never work alone when dealing with spent mushroom compost.

Hydrogen sulphide gas (H2S)

Colourless toxic gas Heavier than air “Rotten egg” smell at low concentrations (pure H2S) Produced by the anaerobic breakdown of Sulphur-containing

organic matter– Animal manures– Plant material

Mushroom Industry: Low levels during Phase 1compost production (short duration

and largely aerobic process) Not produced during mushroom growing phase (aerobic) Can be produced in stored SMC (long duration and anaerobic)

H2S gas

10 (will become 5)Time weighed Average for 8 hours (TWA)

15 ( will become 10)Short term exposure limit (15 mins) (STEL)

700-2000Rapidly fatal

500-600Nausea / Unconsciousness

200Headache / dizziness

150Olfactory nerve paralysis

50-100Respiratory tract

20Mucous membranes

10Irritation of: Eyes

0.01-0.7Odour is detectable

Concentration in ppmEffect

SMC and H2S

No DataNo reports of H2S issues from elsewhereNeed for data to:

– Know what we are dealing with– Identify risks– Enable informed decision making

Teagasc has now gathered some initial data

Initial SMC & H2S studies

Two SMC storage sites during Winter/Spring 06/07 H2S monitoring during removal in Spring 07

One indoor One outdoor

Two contrasting sites

Indoor Storing 10-12 tonne/week Open-sided roofed shed

with 8ft side walls(7 m x 20 m)

SMC only Smaller total volume 20 weeks storage Emptied in one day

Outdoor Storing 50 tonne week Large corner site in field

(30 X 40 m approx)

Some mixed waste Larger total volume 20 weeks storage Emptied over several

days

H2S gas monitors

8 x QRAE plus (100 ppm) 1 x EntryRae (250)(1000) 1 x Impulse Pro (500) Data logging 60 minute average Positions:-

– Above the SMC face– Beside the face– At a distance from the face– On personnel– In tractor cab

Results Site 1 - indoor

Weather : calm, foggy tostart, clearing to sunny inafternoon; winds light

Front loader tractor 4 to 7 scoops of SMC into a

trailer-spreader (approx 5minutes)

Trailer taken to field andspread (approx 10-15minutes)

Same operator drove tractorand trailer

Results Site 1 - indoor

Heap still had heat in it – lots of steam being released

H2S levels at SMC face – Indoor site(I minute averages)

H2S at SMC face between 10:30 and 13.30

0102030405060708090

10:3

0

10:3

8

10:4

6

10:5

4

11:0

2

11:1

0

11:1

8

11:2

6

11:3

4

11:4

2

11:5

0

11:5

8

12:0

6

12:1

4

12:2

2

12:3

0

12:3

8

12:4

6

12:5

4

13:0

2

13:1

0

13:1

8

13:2

6

Time

H2S

con

cen

trat

ion

ppm

Afternoon – Indoor site

H2S at SMC face between 14:00 and 17:00

0102030405060708090

14:2

0

14:2

7

14:3

4

14:4

1

14:4

8

14:5

5

15:0

2

15:0

9

15:1

6

15:2

3

15:3

0

15:3

7

15:4

4

15:5

1

15:5

8

16:0

5

16:1

2

16:1

9

16:2

6

16:3

3

16:4

0

16:4

7

16:5

4

17:0

1

Time

H2S

conc

entr

atio

npp

m

Tractor Cab - Indoor site

H2S levels detected in Tractor Cab (1 minute average)

0

1

2

3

4

5

09:2

0

09:4

0

10:0

0

10:2

0

10:4

0

11:0

0

11:2

0

11:4

0

12:0

0

12:2

0

12:4

0

13:0

0

13:2

0

13:4

0

14:0

0

14:2

0

14:4

0

15:0

0

15:2

0

15:4

0

16:0

0

16:2

0

16:4

0

17:0

0

Time

H2S

ppm

Near Entrance – Indoor site

H2S concentration at entrance to Indoor Shed

0

5

10

15

20

25

30

09:3

0

09:4

6

10:0

2

10:1

8

10:3

4

10:5

0

11:0

6

11:2

2

11:3

8

11:5

4

12:1

0

12:2

6

12:4

2

12:5

8

13:1

4

13:3

0

13:4

6

14:0

2

14:1

8

14:3

4

14:5

0

15:0

6

15:2

2

15:3

8

15:5

4

16:1

0

16:2

6

16:4

2

16:5

8

Time

H2S

pp

m

STEL TWA H2S

H2S levels at SMC face – Outdoor site(I minute average)

H2S concentration at the SMC face - Outdoors. (1 minute averages)

0

50

100

150

200

250

300

11:1

9

11:2

6

11:3

3

11:4

0

11:4

7

11:5

4

12:0

1

12:0

8

12:1

5

12:2

2

12:2

9

12:3

6

12:4

3

12:5

0

12:5

7

13:0

4

13:1

1

13:1

8

13:2

5

13:3

2

13:3

9

13:4

6

13:5

3

14:0

0

14:0

7

14:1

4

14:2

1

14:2

8

14:3

5

14:4

2

Time

H2S

ppm

Tractor Cab - Outdoor site

H2S concentration in Tractor Cab - Outdoor site

05

1015202530

11:2

1

11:3

1

11:4

1

11:5

1

12:0

1

12:1

1

12:2

1

12:3

1

12:4

1

12:5

1

13:0

1

13:1

1

13:2

1

13:3

1

13:4

1

13:5

1

14:0

1

14:1

1

14:2

1

14:3

1

14:4

1

14:5

1

15:0

1

15:1

1

Time

H2S

pp

m

H2S Conc STEL TWA

Near Entrance – Outdoor site

H2S concentration at back grass verge

0

10

20

30

40

50

11:2

1

11:2

911

:37

11:4

5

11:5

3

12:0

1

12:0

9

12:1

7

12:2

5

12:3

3

12:4

1

12:4

912

:57

13:0

513

:13

13:2

1

13:2

9

13:3

7

13:4

5

13:5

3

14:0

1

14:0

9

14:1

7

14:2

5

14:3

3

14:4

1

Time

H2S

ppm

Conc

STEL

TWA

Comparison of sites:

Indoor20 - 80 ppm

0-2 ppm<1<1

5-25 ppm<8<2.5

Outdoor50 – 250+ ppm

3-28 ppm<10<3

0-45 ppm<7.5<1

SMC Face

Tractor cabSTELTWA

EntranceSTELTWA

Conclusions

H2S is consistently released from both large andsmall heaps of SMC stored for 20 weeks or less

H2S is produced whether SMC is stored indoors oroutside

Larger heaps may pose more H&S issues

It is important to keep tractor doors / windows closedduring SMC removal operations

Future work

Additional data for other positions at two sites

Walsh Fellow to work on:– “Dynamics of hydrogen sulphide gas production

in spent mushroom compost during storage andhandling and its impact on Health and Safetyissues”

Objectives

Measure influence of key parameters on H2S emissionfrom SMC at pilot scale

– Indoor/outdoor; length of storage period; size of heap

Characterise microbial activity– Mineralization of organic sulphur

– Reduction of inorganic sulphur

Monitor and correlate levels of H2S emitted from storedSMC at various sites around Ireland during removal withdifferent site characteristics

Prepare guidelines for safe storage and handling of SMC