THE EXTRACTION OF HEAT FROM COMPOST

PILE

Vryheid; KZN ;South Africa

SOUTH AFRICA

PROJECT MEMBERS:

S’phokazi Zondo

Diana Mngomezulu

Qhawelethu Thabede

Sbongakonke Mchunu

ABSTRACT In the school’s waste management project we receive organic

material from the school grounds.

We use these materials to make compost heaps.

We noticed that at certain times when turning the compost the

temperature of the heap was higher than room temperature.

We would like to investigate if it is possible to extract heat from a

compost pile and use that for warming purposes.

Can we use a compost pile as an alternative source of energy?

GLOBE PROTOCOLS

Soil moisture protocol

Soil temperature protocol

Soil pH-protocol

INVESTIGATIVE QUESTION

Can heat be extracted from a compost pile?

HYPOTHESIS

Energy in a form of heat can be extracted from a

compost pile.

BACKGROUND INFORMATION

1. What is compost?

Compost is the natural breakdown of organic material

such as potato peels, other vegetable scraps, hay, grass

clippings etc.

2. When is the compost pile hot?

It depends on the size of the pile, the ingredients and

other arrangements in layers are keys to reaching the

desired outcome.

3. The texture of a finished compost pile:

Damp and moist.

Has dark brown colour

Easy to mix with other soil.

Loose and has a earth-like smell

4. Compost pH:

Should be between 7 and 5.

Compost micro organisms operate best under

neutral and slightly acidic conditions.

5. What makes the compost pile not to heat up?

It depends on the ratio of carbon to nitrogen (C:N)

which is 6:5.

What we needed to make the

compost bin :

Safety goggles

Drill

Welding machine

Plastic barrel (10.2 kg)

Metal rod m(1.8 m)

METHOD

Grinder

Measuring instruments

8 strips of iron metal

(2-3 cm wide)

MAKING THE COMPOST BIN

Drill a 6cm hole on both sides of the drum.

Use a welding machine to join the strips of iron

together to make the compost stand.

Use a grinder to cut the strips and metal rod to

have correct measurements.

OUR COMPOST BIN

What we needed to make the

compost: Potato peels and other vegetable scraps

Loam Soil

Cow dung (Manure)

Brown Leaves

Hay or grass clippings

PREPARING THE COMPOST

PREPARING THE COMPOSTPhase 1:

Place the hay, loam soil, potato peels, food scraps and manure at

a fixed ratio so that the soil is less than the rest.

Close the lid and then leave the compost to decompose. (

Phase 2:

after 24-hours, measure the temperature of the compost and

temperature of the tap water on that day and record.

Place the coffee can filled with water in the middle of the compost

bin.

Rotate the drum for 15 minutes.

Check the temperature of the water after it was put in the

compost bin.

Repeat Phase 2 three times a week for 5 weeks.

TAKING THE MEASUREMENTS

SOIL MOISTURE TEST DONE ON COMPOST

DRYING THE COMPOST SAMPLE USING

MICROWAVE OVEN.

SOIL MOISTURE CALCULATIONm (empty container)=34,1380gm (wet compost)=56,3225gm (dried compost)=49,1919g

Water % by mass= m (wet)-m (dry)/m (wet)= (56,322-49, 1919 /56,322) 100= 12, 66%

TURNING THE COMPOST BIN!!!

MEASUR ING TEMPERATURE OF WATER BEFORE IT I S PUT IN THE COMPOST

RESULTS Week 1 Average

Temperature of the compost (oC)

25.5 24.5 24.6 24.9

pH-Level 7 7 7 7

Moisture Level

2 2 2 2

Week 2 AverageTemperature of the compost (oC)

26.0 25.6 25.6 25.73

pH-Level 7 7 7 7

Moisture Level

2.5 3 3 2.83

Week 3 AverageTemperature of the compost (0C)

32.3 31.9 31.2 32.13

pH-Level 6.9 6.5 6.6 6.66

Moisture Level

3 3 3 3

Week 4 (day1-3) AverageTemperature of the compost (0C)

42.3 42.5 42.4 42.4

pH-Level 6.5 6.6 6.5 6.53

Moisture Level

3 2.5 2.5 2.66

Week 4 (day4-6) Average Temperature of the compost (0C)

49.8 49.9 48,9 49.53

pH-Level 6.5 6.5 6.4 6.47

Moisture Level

2.7 2.8 2.5 2.67

Week 5 AverageTemperature of the compost (0C)

26.0 25.6 25.5 25.7

pH-Level 7 7 7 7

Moisture Level

2.6 2.5 2.7 2.57

Week 1 Week 2 Week 3 Week 4 Week 50

10

20

30

40

50

60Graph 1: Temperature of the compost in the

duration of 5 weeks

GRAPHICAL REPRESANTATION OF THE

RESULT

Week 1 Week 2 Week 3 Week 4 Week 5012345678

Graph 2: pH-Measurements against number of weeks

pH-Levels

Week 1

Week 2

Week 3

Week 4

Week 5

0

1

2

3

4

Graph 3: Moisture Levels against number of weeks

Moisture Levels

T E M P E R AT U R E O F T H E WAT E R B E F O R E A N D A F T E R I T WA S P U T I N T H E C O M P O S T B I N

Temperature of the water before it is put in the

compost bin.

Temperature of water after being put in the compost

bin.

Week 1

Week 2 Week 3 Week 4 Week 5

Temperature (0C)

23 23 22 27 23.5

32.5

22 49.9

22.6

22.6

Change in temperature

No change

Increase Increase Increase No change

Table 6

CONCLUSION Initially the temperature of the compost was 25oC.

The temperature of the compost increased as a result of

mesophilic bacteria.

At approximately 40oC mesophilic bacteria died out and

thermophilic bacteria was produced.

The colour of the compost changed to a dark brown colour and

the volume of the compost started to decrease.

As the microbial activity increased the compost became

slightly acidic.

When the compost was well decomposed the temperature

dropped to 25.7oC and the pH went back to neutral,

thermophilic bacteria died out.

Our compost was always between 2(damp) and 3(wet).

Successful composting depends on the moisture level.

We used a coffee can because it is a thermal conductor.

The change in temperature of the water depended on the

change of the compost temperature.

The more the decomposition the higher the temperature.

From our investigation we concluded that heat can be

extracted from a compost bin and can be used for other

purposes.

REFERENCES

www.sciencebuddies.org

www.endenproject.com

www.compostinstructions.com

www.Homeguides.com

www.biocycle.net

ACKNOWLEDGEMENTSThe Institute for Commercial Forestry Research

Laboratories, University of Kwa-Zulu Natal for the

testing of soil samples.

Mondi South Africa, Dumbe Area Office for the big

they have played: providing a chaperone for the

LANDBOU group and for their contribution on various

areas and involvement in the school for many years.

The Department of Science and Technology for

introducing the GLOBE programme to the school and

financially supporting participation of the school in

the GLE.

The Department of Home Affairs, Zululand District for their

assistance.

The Department of Education, Kwa-Zulu Natal for approving and

supporting this initiative.

Mrs. A van Niekerk (School head) for her support and motivation.

Miss S Khonjelwayo (Physical Science educator, Waste

Management co-ordinator and Globe teacher) for her support,

Science expertise and mentoring.

Mr. L Mathenjwa (Agricultural Laboratory Assistant and the

Globe teacher) for his support administration work and guidance.

The Landbou community – staff, parents and other friends for

supporting us all the way.

The Waste Management team for their support and assistance to

ensure that this project became a success