Sustainable method of phosphorus biowaste management to innovative biofertilizers: A solution for circular economy of the future

This paper presents the possibility of applying bacterial strains from the Bacillus group in the microbial solubilization of phosphorus-bearing waste materials. Fishbones, bones and ash from sewage sludge incineration were used as renewable phosphorus sources. Bacterial consortia in combinations of 1-4 strains were used for phosphate solubilization, including B. thuringiensis, B. megaterium, B. subtilis and B. cereus. Fishbones showed the highest degree of bioavailable phosphorus (20.5% of total content, of which 99.1% was bioavailable). The combination of two raw materials fishbone and sewage sludge ash (1:1) gave the best results of solubilization efficiency (over 70%) using a consortium containing 3 bacterial strains. A consortium consisting of B. cereus and B. thuringiensis, the activity of which resulted in the highest phosphorus concentration in the culture medium, was selected for larger scale tests. The produced application batch of liquid biofertilizer contained 0.54% P2O5 and high levels of micronutrients including iron (0.16%). The biological effectiveness of biofertilizer was confirmed in plant studies, where strong root stimulation (up to 33%) and an increase in chlorophyll content (over 20%) were observed for seeds soaked in biofertilizer. This form of application is being recommended over plant nutrition with granular phosphorus fertilizers. Through the use of waste materials, the research conducted in this paper fits into the topic of sustainability.