Kompostering av utvalgte nye organiske miljøgifter i biorest fra biogassprosessen

The aim of this research was to carry out an established thermophilic-composting experiment to investigate the degradation of five different chemicals of emerging concern (CECs), namely Carbamazepine (CAR), Metoprolol (MTP), Octocrylene, Tris (1,3-dichloro-2-propyl) phosphate (TCPP) and Losartan. Bio-residue was used as a substrate and inoculated with thermophilic microorganisms on a structural material (wood from sawdust use). In the composting method, six Dewar-containers and a gas analyzer were used. The latter measured the concentrations of O2-gas electrochemically, while CO2- and CH4-gas were measured with an infrared sensor. In the composting mass, the temperature and gas measurements were monitored to follow the microbial activity. The six reactors were stopped based on little microbial activity after day 3, day 6, day 9, day 13, day 19 and day 32, respectively. The samples for the respective days were extracted with solid phase extraction, separated by reversed-phase liquid chromatography on a Agilent 1200 high-resolution liquid chromatograph and quantified on a 6490 QqQ LC-MS / MS (triple quadrupole instrument). The composting experiment was considered successful according to the following achieved criteria: (1) good mixing ratio in each Dewar-container between digestate and chopping wood (635 g / 247 g (w/w)) in the starting mixture with 40 % - 65 % moisture, (2) consistent O2 levels of > 5 % in the pore spacing of the compost mass throughout the process, (3) low CH4 emissions (measured to < 1,7 % for all Dewar-containers) and (4) good temperature development through both the mesophilic (40 oC) and thermophilic phase (45 oC - 63,5 oC). The analytical method was found suitable for quantifying all substances except for LOS. One of the most important findings in the composting experiment was that the initial concentrations of OCT and MTP were reduced to below their detection limits (LOD) after day 6 and day 13, respectively. The initial concentrations of TCPP were, however, not reduced below its LOD. Still, consecutive trend measurements of TCPP indicate that further reduction could be expected if the reactor time (day 32) had been extended. The variations in oxygen consumption throughout the composting period may indicate that the aerobic microorganisms switch between carbon sources, and the CECs was further suspected to cause different oxygen consumption levels. During the higher microbial activity period, CAR had one of the fastest reduction rates among the target compounds, regardless of its stability. Still, CAR turned out to accumulate in the composting material in the end of the composting process