Preparation of Phosphate Mine Tailings and Low Grade Rock Phosphate enriched bio-fertilizer

Phosphate tailings pose significant risk to the environment as point sources of basic, carbonate-rich effluents. This waste may be judiciously used for the biofertilizer preparation. The enrichment of compost by adding low grade rock phosphate also offers a potential preposition for the effective utilization of insoluble P. Experimentally, the compostable material (Biogas spent slurry) is mixed well with 2.5, 5, 7.5 and 10% of rock phosphate & tailings were added on wet weight basis. A phosphate solubilizing bacteria Pseudomonas putida and a sulphur oxidizing bacteria Acidithiobacillus thiooxidans were used for inoculation. The treatments were set up as to compare between inoculated and uninoculated treatments. The compost mixtures were incubated for 60 days. The various parameters like pH, EC, volatile solids, nitrogen, phosphorus and potash were determined during the complete span of composting. Out of all inoculated and uninoculated treatments, treatment with 5% rock phosphate and 5% tailings was found best. The effect of inoculated species in the system was not found very significant due to higher activity of the native bacteria. This scheme will certainly help in reducing the wastage of these resources, mitigation of pollution and will generate additional revenue to the company producing this waste.