Investigation of the composting process of input materials from öklo toilettes

öKlo GmbH is an Austrian based company that builds dry toilets and helps with these sanitary units to organize the "waste water disposal" of large events, such as festivals. Besides the installation and operation of the toilets, öKlo also takes care of the disposal of the toilet contents. The ecological aspect of this type of toilet is the application of sawdust instead of chemicals, that are used commonly used mobile toilets to bind odors. However, the use of sawdust excludes a disposal of the residues from öklo toilets in sewage treatment plants and therefore other ways of treatment have to be used. In principle, the mixture of feces and sawdust can be composted in two scenarios. Composting could be performed in the toilets themselves or composting of the residues is made in small composting plants. However, in both the scenarios a sufficient sanitation of the residues cannot be guaranteed. The temperature/time regime required for the sanitation can usually not be maintained due to the low reactivity of the feces. Technical composting offers a guaranteed, hygienically perfect recycling possibility. In this case, the reactivity required for sufficient temperature development is ensured by mixing with the reactive bio-waste and green-waste mixtures, which are co-processed in such plants. The current legal situation, however, prevents the utilization of feces in technical composting plants. Feces are not included in the positive list of permissible input materials of the Austrian “Kompostverordnung 2001” and may therefore not be processed in composting plants. The reason for this are concerns on the process of sanitation. Another open question concerns endocrine disruptive substances, residues of drugs and addictive substances. It is currently not known whether or to what extent these can be degraded in technical composting process. Aim of the current project is to investigate the degree of sanitation to fill existing gaps in the knowledge base.