Valorization of ash and spent mushroom substrate via solid-state solubilization by Acidithiobacillus ferrooxidans

This work describes the possibility of utilization of ash originated from the incineration of sewage sludge from the wastewater treatment plant with the 3rd stage of biological treatment, and spent mushrooms substrate (SMS) as a raw material for the production of the substrate for agriculture and horticulture with the property of slow-releasing of phosphorus via solubilization process. Ash was mixed with SMS in different ratios (1, 5 and 10%), where SMS was used as a substrate/medium - the source of nutrients necessary for the growth of bacteria Acidithiobacillus ferrooxidans (A. ferrooxidans), while the ash was used as a source of phosphorus. Solubilization of phosphorus from ash via solubilization process was conducted for 50 days. During this time pH, conductivity, as well as the concentration of available forms of phosphorus were monitored. Obtained results were compared with the control group deprive inoculation by A. ferrooxidans. The concentration of available to plants phosphorus (express as P₂O₅) was an average 1.5 times higher in the SMS inoculated with A. ferrooxidans in all considered groups. Observation confirms the possibility of utilization of treated SMS as a substrate in agriculture and horticulture as the utilitarian properties (weight and length of plant/root) of plants obtained in germination test were higher when compared with the control group where SMS without inoculation was used.