The process


Order of process

pre-mix

  • reduce moisture
  • mix materials correct C and N
  • reduce particle size

composting

  • aerobic windrow
  • windrow monitoring
  • windrow turning

maturation

  • curing
  • removing plastics
  • quality analysis

Ideal microbial environment for composting

  • Moisture content of 60%
  • Carbon and nitrogen materials mixed at a ratio of 30:1
  • Materials shredded to a particle size between 2 and 20mm
  • 8% oxygen availability in windrows - introduced by either mechanical turning or forced aeration
  • Bulk density of windrow of 450kg/m³

Temperature curve

Composting
      what it is and how we do it

Tens of thousands of tonnes of compost products are used in horticulture, gardens and landscaping to help provide the ideal conditions for plants to grow. Peat was a major component of many branded compost products. Now both producers and users recognise that peat reserves should be conserved. Composts must be produced from sustainable materials.


What is composting?

Composting is the controlled breakdown of organic matter by microbes in the presence of air. The process produces carbon dioxide, water, heat and compost.


The biology of composting

Most organic materials can be represented as a mixture of three groups of chemicals.

  1. Lipids and carbohydrates
  2. Proteins and amino acids
  3. Ash, lignin and cellulose

In the presence of air and water a wide range of microbes break down the material. The lipids, carbohydrates, proteins and amino acids are broken down via a number of intermediates into carbon dioxide and water. At the same time energy is released in the form of heat. It is this biologically produced heat that raises the temperature of the material being composted. The more resistant components of the organic material - the ash, lignin and cellulose contribute to the organic matter content of the final compost.

As the temperature of the compost changes there is a change in the types of microbes in it. Pathogens are sterilised at the high temperatures found during the composting process and the microbial species change between low temperature (mesospheric) and heat loving (thermophilic). Most of these microbes die as the temperature changes and become part of the organic material being broken down. Once the temperature has stabilised, it enters the maturing phase. This is where the easily broken down organic matter has been used up and the product becomes useful as compost.


Windrow Composting

Windrow composting
      at Organic Recycling

At Organic Recycling Ltd we use a natural composting process of open aerobic windrows to produce high quality peat replacement composts from recycled raw materials. These are organic materials, mainly the waste products from fruit and vegetable processing, garden waste, paper and cardboard.

  1. Pre-composting

    Materials are mixed into a windrow within three hours of arriving on site.

  2. Composting

    Using a 360° excavator the compost is turned weekly. The temperature of the compost is taken twice weekly. Once the compost has reached 60°C for three turns it has been sterilised and as the temperature falls it is taken for curing.

  3. Post-composting

    The compost is taken to a maturing area where it is cured for six to eight months. At the end of this time the material is screened down to the target market size. The material is then analysed and goes for sale. Outsized material is then re-composted.