Good management and the right technology helps the climate
Assessments of the Environmental Institute (bifa Umweltinstituts GmbH) Augsburg proved that emissions of climate relevant gases are mainly influenced through operation and rotting control.
Technical measurements like e.g. biofilter cannot separate methane and nitrous oxide therefore the aim should be to avoid these gases during composting.
Besides methane and nitrous oxide ammonia causes an indirect climate relevant effect as it is transformed to nitrous oxide in the atmosphere. The carbon dioxide from the treatment of biowaste can be classified as climate neutral as it can only emit the amount of carbon dioxide that the composted green plants consume from the environment.
The study analysed the emissions total carbon, methane, nitrous oxide, ammonia and non-methane volatile organic compounds. The results of the comparison of different composting processes are shown in the figure.
Composting under a semi-permeable membrane shows excellent results. Assessed have been the following compost processes:
V1: Enclosed composting
V2: Partially enclosed composting
V3: Composting under a semi-permeable membrane
V4: Open composting of biowaste together with green waste
V5: Open composting of green waste
Fundamental to avoid climate relevant gas emissions is among all the management of the aerobic rotting process. Required for this are a favourable C/N ratio, sufficient water content, the dimension and shape of the rotting heap, a corresponding structure material portion, active aeration, the turning processes for sufficient homogenization and the control of the rotting temperatures.
The complete study can be ordered as bifa-text No. 47 Ecoefficient utilisation of biowastes and green waste (in German) at bifa Umweltinstitut GmbH, Augsburg, Augsburg, www.bifa.de