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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. [ABSTRACT FROM AUTHOR]

Research on the plastic contamination of organic fertilizer (compost) has largely concentrated on particles and fragments > 1 mm. Small, submillimeter microplastic particles may be more hazardous to the environment. However, research on their presence in composts has been impeded by the difficulty to univocally identify small plastic particles in such complex matrices. Here a method is proposed for the analysis of particles between 0.01 and 1.0 mm according to number, size, and polymer type in compost. As a first demonstration of its potential, the method is used to determine large and small microplastic in composts from eight municipal compost producing plants: three simple biowaste composters, four plants processing greenery and cuttings and one two-stage biowaste digester-composter. While polyethylene, PE, tends to dominate among fragments > 1 mm, the microplastic fraction contained more polypropylene, PP. Whereas the contamination with PE/PP microplastic was similar over the investigated composts, only composts prepared from biowaste contained microplastic with a signature of biodegradable plastic, namely poly(butylene adipate co-terephthalate), PBAT. Moreover, in these composts PBAT microplastic tended to form the largest fraction. When the bulk of residual PBAT in the composts was analyzed by chloroform extraction, an inverse correlation between the number of particles > 0.01 mm and the total extracted amount was seen, arguing for breakdown into smaller particles, but not necessarily a mass reduction. PBAT oligomers and monomers as possible substrates for subsequent biodegradation were not found. Remaining microplastic will enter the environment with the composts, where its subsequent degradability depends on the local conditions and is to date largely uninvestigated. [ABSTRACT FROM AUTHOR]

Amino‐acid‐derived polyzwitterions and polybetaines (PBs) are two promising alternatives to non‐ionic polymers, for example, to increase tumor permeability. In this study, amino‐acid‐derived polyzwitterions are synthesized and a strategy to quarternize the amine in the side chain functional group is developed to combine the advantages of both types. The functional monomer is polymerized via reversible addition−fragmentation chain‐transfer polymerization for which a kinetic study is performed. Further, the impact of the permanent positive charge on amino‐acid‐derived polyzwitterions is studied based on two zwitterionic polymers obtained via post‐polymerization modification (PPM) of Poly(N‐acryloxysuccinimide) to allow good comparison between methylated and non‐methylated polymers. Circular dichroism shows that the stereocenter remains intact during PPM. pH titration and ζ‐potential measurements show that the methylated polymer has a negative ζ‐potential over the measured pH range and, therefore, the polymer remains zwitterionic over a broader pH range than its non‐methylated equivalent. Both polymers are well tolerated by mammalian cells up to concentrations of 1 mg mL−1. The study introduces a path to a new polymer class that combines the advantages of both PBs and amino‐acid‐derived polyzwitterions and highlights the impact a permanent charge has on the physiochemical properties. [ABSTRACT FROM AUTHOR]