Organic waste is a resource that must be brought
back to nature. This is an important element in adjusting our society to the ecocycle.
Our systems provide a natural solution to the municipal sludge and solid waste disposal
problem today. The organic wastes are converted into high quality compost. Using organic
compost humus and nutrients can be brought back to agriculture and forestry in a
controlled way. Top quality compost is extremely valuable soil amendments that improve a
broad range of soil properties including: porosity, structural and thermal stability,
water retention, and resistance to wind and water erosion.
|Composting is an aerobic process, i.e. oxygen
is needed for the process. The microbes that break the organic material down are
especially bacteria and fungi. The work of the microbes depends very much on certain
conditions. The access to oxygen, the carbon/nitrogen ratio, temperature, the structure of
the material, pH value and the water content are examples of important parameters. If
these parameters can be controlled you can optimise the breaking down process. If, for
instance, the access of oxygen is insufficient the breaking down will stop. Instead an
anaerobic process will start, fermentation, which will be noticed by the nasty-smelling
gas that is produced. If the material is clean it is an advantage if it is disjointed, as
the microbes will have a larger area for their work. On the other hand a disjointed
material is packed together and therefore the access of oxygen will be more difficult.
Big scale composting takes place through one of two basic principles - open air composting
or closed composting. The composting process can also be divided into pre treatment, pre
composting, and post composting and post treatment. Both open air and closed composting
can be equipped with technical equipment that is wanted.
As mentioned there are some disadvantages with
fermentation and open air composting. Therefor the interest has been focusing reactor
composting in a composting drum. With reactor composting the process can be controlled so
the breaking down goes quickly and is more complete and the emissions are possible to
measure and clean. A programme of quality control can guarantee the process and the high
quality of the compost. The finished composed can be returned to producing soil in a
During the 1970's and 1980's several reactor composting facilities were build. The
incoming materials were crushed or grind. As a result unsuitable material from for
instance batteries, cans wit insect repellents and paint were mixed with the organic
material in the composting drum. The process in the drum, which was not divided into
compartments, lasted for several weeks so some metals were dissolved and contaminated the
compost. The sewage sludge often had a low quality and the household waste contained more
unsuitable materials than today. These circumstances led to a low compost quality. Those
effects are often used as argument against big scale composting even today. The quality of
the incoming material has improved and the technology in a well designed composting
facility is quit different from earlier reactor composting. This technology is developed
during many years and is well proven.
||The right composting method
When you are about to decide what technology to choose,
it is important to decide how you look upon the value of the produced compost and in what
way it may be used. It is a great difference if you think it is enough to use the compost
as a layer on the landfill or as bio filter for the methane gas production at the
landfill, or if you think that it may be used as fertiliser in the agriculture for food
production where the quality of the compost is of utmost importance. In other words, it is
essential with a high and reliable quality of the compost day after day so the customers
always can rely on the product. To be able to produce a high quality compost you need a
quality control system.
Another decision is whether sewage sludge or manure from pig or hen farms shall be
co-composted together with the household waste. With our method you can compost with or
without sewage sludge.
There are some different big scale composting technologies and on our homepage we have
described a few of them with quite high level of the process because this is necessary if
you want a useful compost.
Consequently it is important if you think that composting is an expensive way to get rid
of most of the waste, as you reduce the volume very much, or if you think that composting
is a chance to produce a valuable product which is absolutely necessary for productive
soil. It should be obvious that the organic waste is a resource, which must be taken care
of so nutrients and humus can be returned to agriculture and forestry in a controlled way.