Changes in the content of emerging pollutants and potentially hazardous substances during vermi/composting of a mixture of sewage sludge and moulded pulp.

Processing sewage sludge can be problematic due to its potential environmental toxicity. It may contain high concentrations of pharmaceuticals, polycyclic aromatic hydrocarbons, and heavy metals, as well as pathogenic microorganisms. However, it is a good source of organic matter and rich in microbial communities and enzymatic activity. This study deals with composting and vermicomposting of pre-composted mixtures of two different kinds of sewage sludge blended with moulded pulp in an operating composting plant. Of the total number and concentration of pollutants detected in individual piles, a large percentage of them were reduced by the composting process. The composting 2 process resulted in the greatest reduction in contaminating substances--a total of 19 substances by 4.39-90.4%. Some pharmaceuticals accumulated in earthworm bodies during vermicomposting; a total of 11 substances were detected. Atorvastatin showed the highest percentage reduction in compost 2 (90.4%), vermicompost 1 (65.2%) and vermicompost 2 (97.3%). Both composting and vermicomposting appeared to be effective for removal of heavy metals. A higher content of microbial phospholipid fatty acids (PLFAs) was found in composts than vermicomposts. There was a significant reduction in the content of pathogenic microorganisms in both processes, but the reduction in enterococci was not significant.

Changes in layers of laboratory vermicomposting using spent mushroom substrate of Agaricus subrufescens P.

World mushroom production in 2018 was approximately 8.99 million tonnes. The most commonly cultivated species in the Czech Republic are Agaricus spp., which are sold fresh or canned. In 2017, 2018 mushroom production in the Czech Republic was approximately 540 tonnes. Vermicomposting is an easy and less ecologically harmful way to process the spent mushroom substrate. Earthworms, which are referred to as the engine of the process of vermicomposting, and microorganisms, help convert organic waste into fertilizer. This study is concerned with laboratory vermicomposting in a system of continuous feeding of earthworms Eisenia andrei. It compares the differences between variants with and without earthworms. The dry matter percentage was approximately 20% or more in both variants. The variant with earthworms showed a significant decrease in electrical conductivity. The C/N ratio was very low in both variants. The highest total P was recorded in the variant with earthworms, but the highest values of K and Mg were found in the control. Both variants recorded higher content of bacteria than fungi. All values of microorganism contents were higher in the vermicomposter without earthworms, but the bacterial/fungal ratio was higher in the variant with earthworms. The highest content in both variants shows the bacteria especially G-bacteria, on the other side, the lowest content shows the actinobacteria. The highest activity of ß-D-glucosidase and acid phosphatase was measured in the vermicomposter with earthworms, but the activity of other enzymes was higher in the control. In both vermicomposters laccase activity was below the detection limit. The method of classical vermicomposting can be used for processing the spent mushroom substrate. However, in terms of higher content of total and available nutrients, there seems to be a better method of processing the substrate without earthworms.

Change in agrochemical and biochemical parameters during the laboratory vermicomposting of spent mushroom substrate after cultivation of Pleurotus ostreatus.

Pleurotus ostreatus is one of the most cultivated mushrooms in the Czech Republic. The production of 1 kg of mushrooms generates about 5 kg of spent mushroom substrate. A gentle and fast method for using this substrate is vermicomposting. Vermicomposting of spent mushroom substrate using Eisenia andrei was conducted for seven months. For control purposes, a treatment without earthworms was also prepared. The vermicomposting process used vertical continuous feeding vermicomposters. The agrochemical and biological parameters were analysed. Values of electrical conductivity were very high in both vermicomposters (higher than 2000 µS/cm). During the vermicomposting process the C/N ratio decreased. The number and biomass of earthworms decreased with the age of the layers. The values of total P, K and Mg were higher in the vermicomposter without earthworms. There were also lower microbial phospholipid fatty acids content - than in the vermicomposter with earthworms. However, the fungal phospholipid fatty acids content were two times higher in the vermicomposter without earthworms. The highest hydrolytic enzyme activity was found in lipase, acid phosphatase and ß-D-glucosidase. Most hydrolytic enzymes were more active in the vermicomposter without earthworms, with the exception of arylsulphatase. Mn-peroxidase activity was higher in the vermicomposter without earthworms and laccase activity was below the detection limit.