2012
The composting process
Easy guide in practical composting – a REVAS experience
In connection to the development of a composting facility in Jordan, this small extract illustrates the different stages
and phases in the composting process and how to compost from a practical point of view. This document is developped as an easy guide, where the main focus is to illustrate the different processes shown in the different stages in the
composting process.
1st Draft version.
Tobias Breinholt Hoffmann
Gemidan A/S
25-06-2012
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The composting process – The REVAS experiences
by/ Tobias Breinholt Hoffmann, M.Sc.
Background and objective
The background for this small paper is to ensure that Danish composting experience
and know how is disseminated to the joint cooperation partners to REVAS (Part of
the Municipality of Viborg) in Jordan to facilitate knowledge and develop and
implement a composting facility. This paper is a small extract of an overall Master
Plan and deals only with composting of garden and green waste into compost.
The objective of this report is furthermore to produce an easy guide, which by
illustrations shows the composting process developed by Gemidan as entrepreneur
and consultant for REVAS and in this connection implemented by REVAS and
Gemidan in cooperation. This paper has the following content:
Background and objective
Gemidan – short company profile
Composting
The composting concept
Flow diagram of the entire process
Illustrations of the phases
Conclusions and recommendations
Gemidan – short company profile
Gemidan A/S is a contracting and engineering
company that specializes in environmental
technology, recycling, consultancy, professional
dialogue on the environment and operationsand space-optimization for our customers. Our
extremely efficient solutions and competent
consultancy is based on a combination of highly
professional mobile machinery and many years
of experience as pioneers in the environmental
field in Denmark.
1988 - The company was initiated due to the
fact that only 2% of garden/park waste in
Denmark was recycled. The rest did either go
into landfill or were dispatched to incineration plants, which at that time barely had
sufficient capacity. Gemidan A/S is therefore established with the idea of converting
garden/park waste into compost. The concept is further developed on the basis of a
mobile machine pool capable of carrying out decentralized composting at individual
sites. It is therefore no longer necessary to transport waste to centralized sites to
have it composted.
1996 - Gemidan expands its business area and starts wrapping waste as well. In this
connection, Gemidan spreads its wings beyond the Danish border and has since
carried out wrapping assignments in many European countries.
1998 - Gemidan passes yet another important milestone, with the first complete
outsourcing assignment in the production and sale of alternative support fuels
becoming a reality.
2005 - Overall operating solutions at non-company owned composting sites
becomes yet another business area. In this connection, we started developing the
production and sale of composts to farmers.
2009 - Start-up of exports of garden/park waste-based biomass to foreign
customers. Thus far, the staff of Gemidan has grown from two to 35 since 1988.
Composting
Composting is a biological process in which naturally occurring micro-organisms
break down the organic components of plant material into small components and
simple compounds that can be absorbed by the plants.
The best way to produce compost is by shredding the material, turning it and
further shredding it if necessary, before screening the compost in the desired
material. Because the material is heated to 70-75 °C, the compost produced is free
of weed seeds and disease germs.
The concept ensures excellent stability and purity of the finished product, and in
connection with treatment, the machine operator fills in a production form which
sets out selected parameters related to the texture of the raw material. It is this
ongoing record-keeping of the individual compost heaps which helps ensure
ongoing optimization of the final product.
The composting concept
As pressure increases on existing landfill sites, so does the need for solutions which
can efficiently exploit and dispose of the compost from municipalities and waste
treatment companies, among others. Utilizing waste and converting it into
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agricultural compost enables municipalities and waste treatment companies to deal
with problems of space as well as improving their economy.
Agricultural compost, which has only been heaped for 3-4 months and has not
undergone the full composting process, can be used on agricultural land, where it
can be exploited as a soil improvement medium. The compost is made from pure
and sorted garden/park waste. It is spread as a soil improvement medium which
gives the soil structure, as well as supplementary humus and plant nutrients. Humus
functions as a water and nutrient store in the soil.
Gemidan has been documenting the effect of using compost in agriculture through a
number of seasons. For several seasons, Gemidan has monitored the effect by
continuously applying agricultural compost. On the one hand, we have been
carrying out compost analyses of the produced material before spreading while on
the other, we have analyzed the fields the agricultural compost has been spread.
The results speak for themselves. Good agricultural compost is rich in fertilizers
which are released slowly throughout the growing season in step with the plants'
requirements, unlike artificial fertilizers. It also infuses into the soil micro-life in the
form of bacteria and fungi that convert the material into substances which the
plants can exploit.
Healthy micro-life in the soil helps it provide the plants with all the nutrition they
need, and apart from this, the micro-life in agricultural compost can also inhibit
attack by harmful fungi.
Until only a few years ago, artificial fertilizer was the only generally applied fertilizer
supplement, with the exception of farmyard manure. A characteristic of mineral
fertilizers is that the active ingredients of the fertilizer are rapidly released to the
plants. The overall amount of fertilizer required for the season should not be
applied in one go because with high concentrations there is a risk of surplus
fertilizer being leached out of the soil, e.g. by heavy rain. If one discounts the
environmental risks of, among other things, leaching, the price of artificial fertilizers
has been one of the main reasons why an increasing number of farmers now
supplement them with agricultural compost.
3|Side
Flow Diagram of the entire composting process
Illustrations of the phase’s ref. flow diagram
Typical collected Danish garden waste:
Shredding/grinding the waste:
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Building up windrows from shredded/grinded waste
Overview of windrows in the composting process:
5|Side
Flipping the windrows (same process as building the windrows):
Screening the compost (after flipping the compost 3-6 times 9-15 months):
Final Product:
Spreading the compost for agricultural purposes:
6|Side
7|Side