MALU GOING GREEN
MALU’s pig production and Abattoir processes generate high volumes of offal.
We decided to convert this environmentally unfriendly offal into products that can be used as organic fertilizer.
Phase one compost:
The first phase was to start a Compost process using maize bales as the basis.
After harvesting the maize you are left with leftover maize material, this is then baled and the bales are used for cattle feed during winter but mainly as the compost basis.
Fifty maize bales are placed in a row that is approximately 75m in length, per week. The composting process stretch over a period of 16 weeks. During week 1 the bales are wetted with a slurry tanker that incorporates the liquid pig manure through the compost turning machine forming the compost row for the first time.
This process is repeated after 3 days to ensure that the compost row is thoroughly moisturized, thus composting bacteria can start to decompose the material. During the second week of the process, the wetting of the bales will continue and in week 3 the compost will reach a temperature of 60°C – 70°C, indicating that the process is well underway.
The first offal is added to the compost row during week 4. During every working day of the fourth week, 15m of the row are opened to incorporate the day’s offal. For the fifth week of the process, the compost row is left untouched to give the composting bacteria the opportunity to start the decomposing process. Aerobic bacteria are essential for the process, thus these bacteria need oxygen to function well throughout the decomposing process. The three types of aerobic bacteria are: Psychrophilic bacteria (active at 13°C – 21°C), Mesophilic bacteria (active at 21°C – 37°C) and Thermophilic bacteria (active at 45°C – 71°C).
From week 6 the compost row is examined on a regular basis. The examination process is as follows:
1. A hand full of compost are pressed in one’s hand which must leave your hand to appear damp (not wet). If it is not wet enough we add more slurry.
2. Measuring a high temperature is an indication that the bacteria are well at work. If the temperature is below 45°C the compost turner is used to air the compost again allowing oxygen to improve bacterial activity.
The examination of the compost are repeated week after week until week 14 to 16 when the composting process should be finished and all the material decomposed by the aerobic bacteria. The process is finished when the compost does not get warmer after aeration anymore, nor does it react when the slurry is added and the material has a fine texture.
Phase two liquid fertilizer:
This is done by pumping the slurry through a sepcom vertical screw press with a 0.45mm aperture size. The dry matter is used in the composting process while the screened liquid is used as liquid fertilizer irrigated by our centre pivots.
