During the disposal of biobased plastics, carbon absorbed by the plants (biogenic carbon) is released again, whereas during the disposal of fossil-based plastics, "additional" carbon as released into the atmosphere as CO2
. A distinction is made between four disposal routes:Thermal disposal
In Germany, the majority of plastic waste is disposed of in waste incineration plants. At present, a very well-developed recycling system is available only for PET bottles. Film remnants of all kinds that are smaller than A4 are added to the mixed plastic fraction (MKF) and are burned.
During thermal disposal, a small proportion of the energy is recovered. This means that there is - albeit short - cascade utilisation. (The material and ultimately the energetic utilisation of a raw material for as long as possible over several stages is referred to as cascade utilisation or multiple utilisation).
The publication "Disposal Routes and Recycling Options of Products from biobased Polymers from the Post-consumer Sector" from Knoten Weimar GmbH provides a good overview of disposal and recycling: 
Knoten Weimar GmbH is an engineering company operating internationally that develops and provides optimal solutions for improving infrastructure in the field of recycling and disposal (waste, waste water, energy) for the concrete specific situation on site from an ecological and socio-economic point of view.Recycling
Post-consumer recycling: recycling of biobased plastics that are not identical in terms of structure (including PLA, cellulose-based plastics, starch blends) has not been realised on an industrial scale until now.
The reasons for this lie in the mass fluxes that remain low and in the anticipated costs associated with setting up sorting systems in addition to those for PET, PP, PE and PS. At present, the biopolymers found in low quantities in the waste streams are assigned to the group of so-called mixed plastics (MKS).
The economic benefit of recycling materials of a single type or of only one sort depends on many factors, including the revenue situation for the material to be disposed of or recycled, the sort of polymer, the market price for the corresponding recyclate, raw material prices and the necessary sorting and processing technology. 
The technical capability to recycle other materials separately, in particular of PLA by means of near-infra-red spectroscopy, already exists today with the appropriate equipment.  
. Feelings of resentment towards the new plastics are harboured especially on the part of the disposer who on the one hand fears costs associated with setting up the new systems and on the other hand views the mixing with conventional plastics with a great deal of scepticism. The following problems are anticipated: pollution of industrial process water and a rise in the biological oxygen demand (BOD value) during washing processes, flotation, sink-float separation methods. 
Moreover, it is important to note that manufacturers prefer composting when disposing of starch blends and cellulose-based plastics. Both materials degrade well, although to date the decomposition of PLA has not been fully achieved even in industrial plants if dwell times are not reached.
Feedstock recycling could be an alternative to mechanical recycling if materials are available in sufficient quantities. A clear advantage of lactic acid plastics such as PLA is that they can be hydrolytically decomposed into their building blocks relatively easily. New bioplastics can be subsequently manufactured from these. Contaminants from food scraps, paper and aluminium lids etc. are critical here. 
Pre-consumer recycling: For economic reasons alone, recycling of internal production waste has already been put into practice in many companies for years. For example, companies recycle their PLA salvage. Difficulties in repeated crushing and feedback in the recovered substance cycle have only been reported in a few cases. 
A good overview of disposal routes and recycling options for products from biobased polymers from the post-consumer sector can be found at KNOTEN WEIMAR GmbH. Composting (see also 1.3 certifications)
Definition of terms biodegradability
"Biodegradable plastics are polymer materials that are mainly decomposed into biomass and inorganic substances under defined conditions within a specified time by microorganisms and/or fungi. Various standards exist for the exact underlying condition, e.g. DIN EN 13432 and ASTM D6400, which are specially designed for the decomposition in industrial composting facilities. Differences can primarily be found in the degree of degradation and in the periods of time available for this." 
There are various guidelines for the certification of biodegradability of materials in composting facilities, all of which are based on both of the aforementioned standards and confirmed by several organisations with the appropriate certification mark. The DIN CERTCO (Society for Conformity Assessment mbH) and the AIB-Vinçotte with the "seedling" and "OK Compost" certification marks play a leading role in Germany and the European area in this regard. 
DIN EN 13432 - "Requirements for Packaging recoverable through Composting and Biodegradation":
This European standard ensures that the product can be composted industrially and that not only the plastic itself, but also all the other product components are compostable, e.g. colours, labels, adhesives, food residues. 
ASTM D6400 - "Standard Specification for Compostable Plastics":
This American standard ensures that the product can be composted industrially. In contrast to DIN EN 13432, a degradation rate of 60% within 180 days is prescribed. DIN EN 13432 stipulates a degradation rate of 90%.
More specific information can be viewed here: 
There are two certifiers for biodegradability, DIN CERTCO Gesellschaft für Konformitätsbewertung mbH 
and the AIB-Vinçotte (Europe) 
The Vincotte certification "OK Compost" or "OK Compost Home" certifies the biodegradability of materials in industrial plants or at low ambient temperatures such as in garden compost. DIN CERTCO awards the "seedling" certification mark.   
You can find more information concerning the standards, certifications and labels in the field of composting here: 
The Biowaste Ordinance (Ordinance on the Utilisation of Biowastes on Land used for Agricultural,
Silvicultural and Horticultural Purposes (Bioabfallverordnung – BioAbfV)) describes which waste is permitted for disposal via the composting bin. Any plastic packaging with the exception of biowaste collecting bags is not permitted. The public waste management organisation on site decides whether to permit the disposal of the bag via the organic waste container. Many municipalities have explicitly forbidden this.
In many composting facilities in Germany, all plastics are currently being sorted anyway, because no distinction can be made between biodegradable and conventional plastics.
Industrial composting always requires an energy input. It is disputable if the rotten material promotes growth in the soil. 
Since the biodegradable plastics usually contain no nutrients (e.g. P and N), they do not contribute to the nutrient supply via compost. 
The decomposition (rotting) is dependent on the type of plastic, additives and veneers. 
Inadequate decomposition arising during composting can prove problematic at times. One reason for this is that the dwell time in the system is often too short Fermentation
Fermentation constitutes a further way to dispose of biodegradable plastics.
Advantages of fermentation compared to composting include,for example, lower emissions of methane (CH4
), ammonia (NH3
) and nitrous oxide (laughing gas) (N2
O), the use of plastic waste through anaerobic fermentation and gas utilisation in thermal power stations or in the natural gas grid. 
At present, recycling in a biogas plant only sometimes has a significant ecological advantage. 
Studies on the topic of fermentation:
• Endres, H-J., Kitzler, A-S. (2013): Multiple utilisation of biopolymer materials. Hochschule Hannover, IfBB. 
• Dinkel, F., Kägi, T. (2013): Life cycle assessment disposal. Environmental comparison of biodegradable materials BAW: Disposal in a MWIP vs. disposal in a biogas plant. Carbotech AG 
• Grundmann, V., Wonschik, C-R. (2011): Hydrolysis and anaerobic co-fermentation of various biodegradable plastics. Müll und Abfall. 07/2011.