PROJECT
INCORPORATING COLD CHAIN
The compost ( with the mushroom spawn ) is placed into aluminium shelves and topped with a 5cm layer of peat .
steam , they should produce 25 tonnes of mushrooms a week !
Although the electricity bill was lower at the old site , there were the added costs of boiler fuel for growing tray sterilisation . The old site used about 17 000 litres of fuel a month for sterilisation . Not to mention that in winter , they used to have heating elements in the ducts , which almost doubled the electricity bill . Now that the new system has heat recovery built in , this is a great saving as the water is mostly heated by the chiller .
The rooms all have hot water and chilled water feeding through . Fresh water is fractured through a nozzle and compressed air to get the humidity . Negating the fuel expense of a boiler to create humidification was also a bonus here .
ALL ABOUT CONTROL
During the peak summer months , it is quite hot in the area and with often high humidity levels , the air takes longer to cool . That is why it is essential to take into account the environment you work in , explains Baring Richardson . “ You need a climate control system that can cope with the environment .”
Each one of the rooms is equipped with climate control to ensure the best possible yield .
When trying to understand the role that HVAC & R plays in a mushroom farm , it is crucial to first understand the various stages of mushroom growing and the requirements for this fine science . Temperature and humidity play a crucial role in the production of mushrooms .
MUSHROOM GROWING
Mushroom growing is a highly complicated production process involving both nature ’ s processes and technology . Luckily , Highveld Mushrooms ( the majority stakeholder in Medallion Mushrooms ) has all the info broken down into the following main steps :
• Step 1 Compost making
• Step 2 Pasteurisation
• Step 3 Spawn running
• Step 4 Case running
• Step 5 Airing
• Step 6 Cropping
• Step 7 Packing and delivering
• Step 8 End of crop and compost disposal
1 . COMPOST MAKING Compost is the substrate that the mushroom feeds off and is made from wheat straw , chicken manure , gypsum , and water . Compost is made following a recipe that is constantly altered based on the structure and quality of the raw materials .
Medallion uses large bunkers that are at the forefront of composting technology . One main advantage is that air is supplied through holes in the floor . This ensures that the composting process occurs aerobically ( meaning with oxygen ) and so odour is limited . The converse is anaerobic compost making , which is without oxygen and that is when bad odour is generated .
This process takes approximately two to three weeks depending on the time of year . Interestingly , the internal compost temperatures during this process can go as high as 84 ° C as a result of the chemical and microbiological reactions that are taking place .
After a few days , the mushroom mycelium grows from the compost through the wet peat to the top of the mushroom beds .
The mushrooms are picked by hand once fully grown .
14 www . coldlinkafrica . co . za COLD LINK AFRICA • May 2018