Frequently Asked Questions About Composting

What is composting ?

A biological processes which use oxygen (O2) for the degradation of organic waste to produce a new smaller enriched biomass.

C6H12O2 + O2 => CO2 + H2O + new biomass

What is needed in compost?

  • Oxygen (O2)
  • Carbon additives
  • Moisture
  • Microorganisms

Why do we need Oxygen (O2) ?

Composting is an aerobic process ( when oxygen is available). If oxygen is not available, the process is anaerobic (methanisation).

Why use carbon additives?

There are three main reasons for using carbon additives:

  • carbon must be added to balance the ratio of carbon/nitrogen (C/N)
  • for structure, providing air pockets and pores for gas exchange
  • to absorb moisture, generally the waste is rather wet ( ideal humidity 50-60% )

Why is moisture important?

If the compost material is too dry, the will be no composting process.

What is required for the well-being of the microorganisms ?

  • Ideal humidity 50-60%
  • The composter is well insulated with good ventilation
  • Access to oxygen
  • Balance between carbon and nitrogen is 25/1 – 30/1
  • The waste to be composted is ground and/or cut into small pieces

Why should we compost?

  • Organic waste is the largest part of domestic garbage
  • Compost can be used as a soil improver and as a fertilizer instead of chemical products
  • For economy as it reduces the costs for garbage disposal
  • It reduces the cost to transport garbage from residences to landfill sites

Is the compost soil a valuable resource?

  • Nutrient values are comparable to cow manure
  • Excellent as a soil improver
  • Fertilizer with long time effect
  • Topdressing of lawns
  • Flowers beds
  • Pots and baskets

What are the advantages of local composting?

  • Less heavy truck traffic in residential areas
  • Less waste transport and use of fuel
  • Fewer purchases of soil and fertilizers
  • Increases in recycled material
  • Increase in environmental awareness
  • Savings of both personal and municipal expenses

What are the central composting issues?

  • Manpower is needed to sort compostable material
  • The final product is not as valuable and takes longer to compost
  • Transport to and from the central treatment plants is expensive and uses fuel
  • At the moment, most biodegradable material is not being composted and ends up in landfill sites
  • Weekly collection is necessary for hygienic reasons

Why compost locally?

  • Easy to implement, independent of present system for waste treatment
  • Fewer collections
  • Fewer transport, less impact on environment
  • Increase in personal willingness to sort waste material
  • Higher quality of the end product
  • Less expense for soil improvers and fertilizers
  • Transportation of waste materials can be up to 75% of the cost of garbage collection

What about the presence of heavy metals in composted material?

Metal Symbol Results (mg/kg) Limits (mg/kg)
Zinc Zn 32,0 < 300
Lead Pb 0,58 < 100
Nickel Ni < 2.4 < 50
Mercury Hg 0,12 < 1
Copper Cu < 2,5 < 100
Chrome Cr 0,14 < 1

Analysis performed at Familjebostäder, Siriusgatan in Göteborg, Sweden

What are the advantages of using a JK 5100 industrial composting machine?

  • When compostable paper bags are used, no empty bucket need to be taken back to the apartment to be cleaned
  • If the machine is equipped with an automatic pellet dispenser, no pellets are added manually
  • The material is mixed and aired automatically
  • The compost is ready in 4 weeks versus 1 year at a composting plant

How much compost will the JK5100 handle?

  • 2.3 litres of organic waste per person per week
  • 2.3 litres x 52 weeks = 120 l/year
  • + 12 litres of sawdust pellets/year => 132 litres per person
  • 130 litres of organic waste <= > 20 litres of ready compost annually
  • 6.5 to 7 times reduction in volume
  • One JK5100 machine will handle the organic waste of 230 people per year.