Enriched Biocompost production from rice straw using biotechnology approaches at pilot scale

Various type of agricultural waste is produced annually in the world, which have not found special application in many parts of the world. Using microorganisms with high hydrolysis activity to convert waste into compost is one of the alternative methods of incineration. In the present study, after screening the enzymatic activity of Thermoascus aurantiacus, Trichoderma sp, Bacillus licheniformis, Nocardiopsis alba and B. subtilis bacteria along with the optimization of other additives, the possibility of compost production from rice straw was investigated.

One fungal and three bacterial strains were isolated from another compost and their hydrolysis power were evaluated on specific media. Compost production was performed by optimizing the additives along with the superior microorganisms including M1 (Bacillus licheniformis, Nocardiopsis alba, B. Subtilis and Thermoascus aurantiacus) and M2 (Bacillus licheniformis, Nocardiopsis alba, B. subtilis and Trichoderma sp.) in enzymatic activity in the form of 6 treatments with 3 replications for 8 weeks. Physicochemical properties of temperature, pH, EC, C/N ratio, amount of heavy metals and nutrients, toxicity and impact on wheat growth during eight weeks were investigated.

Studies showed that fungal strain T. aurantiacus and three bacterial strains Bacillus licheniformis, Nocardiopsis alba and B. subtilis has the highest enzymatic activity in the breakdown of xylan, cellulose, lignin and starch. Treatment G (containing poultry manure and T. aurantiacus) caused a significant increase in temperature of rice straw mass (63 °C) and also a significant decrease in C/N ratio (73.48%) (at the pilot level). Germination index test showed that G treatment did not have phytotoxicity and had the most positive effect on wheat growth indexes compared to the control.

According to the comparison of treatments with and without microorganisms, it was found that the hydrolysis power of T. aurantiacus has the most positive effect on physicochemical properties, especially reducing the C/N ratio and can be used as a commercial additive in compost production.