COMMUNITY LEVEL COMPOSTING OF MUNICIPAL SOLID WASTE

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RISE-AT Waste Management Factsheet 2 Community Level Composting of Municipal Solid Waste Temperature and Composting:- If a compost pile has enough water and oxygen and a good balance of organic material, temperatures in the pile will rise and can reach 65°C. Heat is the result of the microorganisms that are decomposing the organic material. After building the pile it should heat up within a few days – this shows that it is working. If it does not it may not contain enough green materials or may be too dry. As the oxygen in the pile is used up the decomposition will slow down and so the temperature in the pile will drop. This drop in temperature is a good indication that it is time to turn the pile and add more oxygen. It is important to note that a temperature of 55°C or above is required for about 3 days to kill any pathogens, (disease causing organisms), that may be present in the waste. When starting a composting facility it is recommended that pilot tests are performed at first to determine the how often the piles should be turned and the time it will take before composting is complete. No definite figures can be provided here as these parameters will vary from place to place depending on the pile design, climate, waste contents, etc. These times can be determined by monitoring the temperature of the first few piles built and using the drop in temperature to determine when the piles should be turned. . Once the system has been running for a while, the regularity of turning the piles will become apparent and constant monitoring of every pile should not be necessary. Temperature Monitoring:- If you want to monitor the temperature of the pile accurately a thermometer can be used to take the temperature in the middle of the pile. It is often more accurate to take several readings at different points around the pile and to use the average of these values. In general the temperature should be between 45 – 65°C and if the temperature drops below 45°C the pile should be turned. An example of temperature monitoring is shown in Figure 5. Poles are used to make holes in three points around the pile, the thermometer should be placed in the hole and left for a few minutes, if the thermometer is small, it should be connected to a piece of string so that it can be pushed into the centre of the heap. The hole can then be covered to stop heat loss, and the string can be used to pull the thermometer out when ready. The reading must be taken as soon as the thermometer has been removed. If there is any delay the temperature reading will drop rapidly as it is affected by the ambient temperature. Page 12
RISE-AT Waste Management Factsheet 2 Community Level Composting of Municipal Solid Waste Figure 5: Temperature Monitoring A more simple, non-technical method is to allow a metal rod to heat up in the middle of the pile. Take it out and hold the hot end. If it can be held comfortably in the hand for only 3 seconds, the heap is hot enough and should be left. If it can be held comfortably for longer than 3 seconds the pile should be turned. You should find that the turning is required once every 5 to 7 days for piles of the size described in this factsheet. STEP 3 – HOW TO TURN THE PILE As the pile is turned: - Fresh air is mixed with the waste material - Excess heat is released - The material is broken up into smaller particles - The moisture content can be monitored and excess water added if necessary - Material from the outside of the pile is turned to the middle, where it will heat up. This will ensure that all of the material sees the higher temperatures at the middle of the pile. This will kill disease causing organisms in the waste and will also help to kill the fly larvae which often accumulate under the surface of a compost pile, see figure 6. Page 13
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COMMUNITY LEVEL COMPOSTING OF MUNICIPAL SOLID WASTE

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