Do you guys still remember recycling issues in I/GCSE Biology?

• In UK – over 7.6 million tonnes of food wasted

• Food + drink wastes = organic – originally come from plants / animals
• Waste decay as bacteria, fungi grow on them
• Refer to I/GCSE Biology, most UK waste disposed in landfill sites – once organic waste buried, decay organisms can’t grow – not enough oxygen for aerobic respiration
• Decay method – methanogens can grow anaerobically – release methane (flammable + global warming)
• Meat waste attractive to pests e.g. rats, councils ask to separate waste e.g. cans, glass, food etc.
• Landfill tips vented in a controlled way for many years after tipping has ended, otherwise methane that forms as the refuse decays might explode or create fires that burn below the surface for weeks.

• Manage garden + vegetable kitchen waste = compost heap – waste piled up and microbial decay breaks it down into compost
• Councils collect this as green waste – make compost in large scale, process called windrow composting – needs space + compost material turned regularly (keep oxygen level hug) no special equipment needed
• Windrow composting -outdoor composting on a large scale
• Other councils collect garden + kitchen waste together – composting in large containers until meat waste is broken down, process called In-vessel composting

• In-vessel composting – forming compost from waste plant material within a large vessel in which conditions of temperature and moisture can be controlled
• Composting complete by using windrow process
• Advantage – conditions monitored inside containers + correct moisture + temperature maintained
• The high temperatures kill pathogens + seeds of weed plants
• In I/GCSE Biology,  Other process = anaerobic digestion = the breakdown of dead plant and animal material without oxygen
• Food waste put into large digesters + air is excluded
• Methanogens break down material + release methane – methane collected, used to produce heat – process can’t use wood waste because microorganisms can’t break it down
• In all processes, the solid end materials can be used for soil conditioning (gardens, parks etc.)

That's all~

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