Biodegradable plastics are increasingly proposed as environmentally friendly alternatives for disposable dishes or glasses in addition to their more conventional uses as foils and in bags. If produced from certified degradable materials, such items are expected to degrade rapidly during state-of-the-art composting. However, conditions prescribed for the testing and certification of materials differ from those typically applied in industrial composting, and operators of the corresponding plants have found that degradation is incomplete. In this study the degradation of commercially available biodegradable bags as well as disposable sparkling wine glasses was studied in a series of pilot-scale composting campaigns closely mimicking state-of-the-art composting conditions. The materials were characterized regarding their chemical composition, structure, and crystallinity, as well as the changes thereof throughout the process. Evidence is given that parameters such as crystallinity change significantly during composting, which may inhibit breakdown during the process and thus have unknown consequences for the subsequent environmental impact.

Biochar (BC) is often used as an additive in anaerobic digestion (AD) to increase yield and/or to stabilise the process when the manure content is increased. Unfortunately, BC is rarely described in detail in terms of its raw material sources, production processes, and structural, physical and chemical properties to allow correlation with its effects on AD. It is an open question whether microorganisms from AD can penetrate into different biochar pore types, depending on their wood origin. In this paper, we describe the preparation (temperatures, treatment times, yields) and characterisation shrinkage, density, pore sizes, pore size distribution, specific surface area, ash, volatiles, fixed carbon, elemental composition, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), benzene, toluene, ethyl-toluene, xylene (BTEX) and volatile halogenated hydrocarbons (VHH) of BC cubes of Scots pine (Pinus sylvestris) and common beech (Fagus sylvatica) powder made from this BC in addition to commercial charcoal powder. The pore size distribution determined by mercury porosimetry differs from that determined by 3D-reflected light microscopy. After incubating BC cubes in AD, the cubes were mechanically cleaned and cut into two pieces. Microorganisms were detected inside the cubes by fluorescence microscopy. Particle size and wood source determine the influence of BC on AD.