Leaflet no. 83. That's rot!

Rubbish may be left in the street or taken to dumps to rot. Rotting rubbish piles become smelly, and unpleasant to look at. Worse still, they attract flies and other germ carriers. So the faster the material rots, the better. This leaflet explores ways that the decaying process can be speeded up. Use what you learn to make a critical assessment of your local dump, and come up with ideas for improving it.

Activity 1: What rots?

You will need:

* one piece of trash from the following categories:

food waste (such as a orange rind, apple core)
farm waste (weeds, leaves)
paper (e.g. newspaper, a piece of cardboard)
metal (e.g. a key, a piece of wire, a soda can tab, paper clip)
glass (e.g. a small glass bottle)
cloth (e.g. an old sock, a scrap from a torn shirt)
wood (e.g. some pencil shavings, sticks)
plastic (e.g. a small plastic bag)

* 8 transparent plastic bags

* pencil and paper for recording results

1. Examine each of the eight items. Use your sight, smell and touch to describe the colour, texture, shape and feel of each one. Write down which items you predict will change in (a) a week (b) two weeks and (c) a month.

2. Put each item in its own plastic bag, and tie the bag so the item is sealed in. Set them aside for a week.

3. After one week, find out which items have changed, and which have not changed. Record your observations.

4. After two weeks, record new changes.

5. After a month, record new changes. Which items have changed? Were your predictions correct? Which items have not changed? Do you think these items will change after a year, after several years?

IMPORTANT: After completing this experiment, carefully bury the 'change' bags without opening them. Some moulds that feed on organic material and help it rot can make you sick.

Activity 2: Aids to decay

What helps stuff rot or breakdown? Here is an experiment to test variables, such as water, soil, air and light, that may or may not help make stuff rot:

You will need:

* 5 pieces of banana peel, all the same size;
* 5 transparent plastic bags;
* water;
* soil taken from a place likely to contain microorganisms, such as under a tree or a bush;
* pencil and paper for recording results.

Figure

1. Put a piece of banana peel in each of the plastic bags.

2. In bag 1, cover the peel with soil. Squeeze out most of the air, and tie the plastic bag to seal it.

3. In bag 2, squeeze out the air, seal the bag, and leave it in a sunny place.

4. In bag 3, cover the peel with water. Squeeze out as much air as possible and tie the bag to seal it.

5. In bag 4, poke holes in the bag, and leave it open so the peel is exposed to air.

6. The peel in bag 5 is to serve as your control. It will not be exposed to air, soil, water or sunlight. Squeeze out the air and seal the bag.

7. Place all the bags, except for bag 2, in a dark place, and leave for a week.

8. After one week, look at the bags, but do not open them. Do you notice any changes in the banana peels? Consider colour and texture. Record the changes in a chart similar to the one below:

Observations	1 Soil	2 Light	3 Water	4 Air	5 Control
Changes in peel after 1 week 2 weeks

9. After two weeks, repeat step 8. Did all the peels change? Did the peels change in the same way? Which changed the most, the least?

10. Bury the unopened bags once you have completed this experiment.

Extension Activity: Test other variables on the banana peel. Also try this experiment but instead of pieces of banana peel use pieces of newspaper or other waste items.

Activity 3: Make a 'rotting pot'

From the previous experiment, you should know which variables help make stuff rot. Now try making a 'rotting pot' - a container in which stuff can decay fast. You will need:

* a large transparent container (Probably, the best type is a 2-litre plastic soda bottle which has had the top cut off. Keep the cut-off top.);

* samples of rubbish (items described in Activity 1);

* soil with microorganisms;

* water;

* tape.

1. Place trash in the container, and use what you have learned in Activity 2 to add the things you think will help the trash rot quickly. Think about how these things should be added. For example, if you think air is a requirement for speedy rotting, you may simply puncture the container, or you may try to work out a more elaborate ventilation system. You may decide to add the container top to the pot and seal it with tape, or you may leave the top off the pot for all or part of the time.

Figure

2. Once the pot has been prepared, it should be left undisturbed for a few months. Decide whether the pot should be left in the dark or light, in a place that is dry or humid, warm or cool, windy or sheltered.

3. Check on the 'rotting pot' on the same day each week, and observe and record any changes you notice.

4. Can you think how you might be able to improve your 'rotting pot'?

One suggestion: have your friends carry out this experiment at the same time. They can prepare their pots in different ways, and you can all compare results to find out which 'rotting pot works best.

Activity 4: Investigate your local rubbish dump

Use what you have learned in the above experiments to find out how well rubbish rots at your local dump. You can also look at how safe the dump is.

(a) Draw a plan of the dump which shows the size of the landfill, and its situation in relationship to nearby houses and other buildings, roads, rivers, streams and other drainage channels, etc.

(b) Below is a list of things to look out for, and questions to ask the people at the dump. (You may need permission to visit the dump.)

1. How big an area is the dump site, and is it surrounded by a fence?

2. How far away from the dump are (a) houses (b) sources of drinking water - streams, springs etc.?

3. When rain falls on the site, where does it drain?

4. Does the wind generally blow from the dump towards where people live or away from where people live?

5. Who owns and operates the dump site?

6. Is rubbish dumped in a depression, and how deep is the hole?

7. Was the hole lined before dumping began? (If so, what material was used as a lining?)

8. How much rubbish is being dumped every day? Every week?

9. How much rubbish can the dump hold, and when is it likely to be fall?

10. What types of materials are dumped on the site?

11. Is any hazardous material dumped on the site?

12. Has material that can be re-used, recycled or composted been removed before rubbish is dumped on the site, or do people sort out the rubbish after it has been dumped?

13. How long is the rubbish on the dump left exposed to air before any material is placed on top of it?

14. Is the dumped material compacted (squashed down), and what effect does this have?

15. Are layers of dirt put in between layers of rubbish?

16. Is the rubbish dump covered each night with covering material such as soil?

17. Is leachate collected? (Leachate is liquid that has soaked through solid waste and/or been created by rotting garbage, and has dissolved or suspended materials such as bacteria and toxic substances in it.)

18. Is groundwater tested for leachate pollution?

19. Is methane gas (given off by rotting garbage) recovered? If so, what is the gas used for? To heat homes, to cook food?

20. Have measures been taken to avoid fires from breaking out?

21. Are rats and other disease-carrying animals present?

22. Is the dump closed at night?

23. Are there are washing facilities available for people working on the dump?

24. Have plans of the site been drawn up to show what will happen to the dump when it is full?

What do you think about the dump? Will the rubbish be able to break down easily? Is as much waste as possible re-used, recycled and composted before it ends up in the dump? Do you think the dump is a safe place to live near and work at? What improvements would you make to the dump?

Prepare a report on your survey findings. Use drawings and charts to illustrate the text. Present your findings to the owners of the dump, to the local authorities and to the local community so that these groups can determine if improvements ought to be made.

Sources of reference: Jean F. Bonhotal & Marianne E. Krasy, Composting: Waste to Resources, A Cornell Cooperative Extension Publication, Cornell University, New York USA (1990); SuperScience Blue Edition Vol.2, No.1 September, 1990: "Rot This!" published by Scholastic Inc. 730 Broadway, New York, NY 10003 USA.

OUTREACH pack 95 pp 5-6. Other Learning-By-Doing Leaflets and Information packs arc available from Dr. James Connor, OUTREACH Director, Environmental Education Center, 200 East Building, New York University, New York NY 10003, U.S.A. or Richard Lumbe, OUTREACH Coordinator, Information & Public Affairs, UNEP, P.O. Box 30552, Nairobi, KENYA