Microbial processing of tannery waste for compost production in the growth and quality improvement of ornamental plants

Research goal: The article presents research results that aim to highlight microbial activity in the composting process of waste from tanning industries. The various steps of the compost production process with microbial inocula and the resulting stable material for the production of growing substrates for ornamental plants are emphasised. Materials and Methods: The experimentation was divided into two phases, a first part of the transformation of tannery waste by microbial activity took place at the company Sirp spa (VR), and the second part of the evaluation of the material for plant cultivation was carried out at the CREA-OF greenhouses in Pescia (PT). The experimental theses involved using peat and biological sludge, respectively, treated with microorganisms in liquid form, supplemented with a solid matrix colonised by microorganisms, and added with sugar cane molasses. Results and Discussion: The test showed that it was possible to cultivate Delosperma cooperi plants on biological sludge treated with microorganisms, showing an improvement in the agronomic characteristics of the plants and substrates in which the microorganisms were inoculated during the composting phase. In general, a significantly more significant improvement in the theses treated with liquid microorganism solution than when a solid organic matrix was used as a substrate for inoculating the microorganisms. Furthermore, the biological sludge treated with microorganisms was better than the peat controls and those treated with sugar cane molasses alone. Furthermore, the untreated biological sludge thesis was the worst of all the theses tested. Finally, the trial also showed how the use of microorganisms could positively and significantly influence the reduction of some essential industrial contaminants in biological sludge after only six months of treatment. Conclusions: This research may interest growers who want to reduce synthetic chemicals in agriculture and are concerned about sustainability, but also those companies whose primary goal is to produce new substrates as an alternative to peat and who are looking for new matrices. Also, for those industries that are environmentally friendly and want to transform the waste produced by their industrial processes and reuse it, perhaps to grow ornamental plants