Transforming wet blue leather and potato peel into an eco-friendly bio-organic NPK fertilizer for intensifying crop productivity and retrieving value-added recyclable chromium salts

An attempt has been made to address two important issues, the solid waste management of leather industry and soil fertility. The SEM images revealed altered surface-morphology.The EDS elemental analysis exhibited presence of about 13.2% nitrogen (N), 50.56% carbon (C), 2.69% phosphorus (P) in the collagenous material of wet blue leather (WBL) after chromium removal. In potato peel biochar (PPB) prepared the EDS analysis corroborated the presence of N P K in 5%, 1.4% and 21.64% respectively. In the formulated bio-organic NPK fertilizer, using chromium free WBL and PPB, the percentage of N, P, K, was in 13.10, 2.41, 20.20% respectively which was authenticated by EDS. Its effect on okra (Abelmoschus esculentus) plant showed higher growth (1.11 fold fruit size) and total chlorophyll content (1.61 fold) than in untreated soil (control) but displayed similar result as in presence of chemical fertilizer. The released free ammonia in soil with bio-organic NPK was more (37.02%) than with chemical fertilizer (6.10%). DNA intercalation study showed the non-hazardous impact on soil. The FTIR, XRD, SEM-EDS, AAS further specified the conversion of the WBL extracted acidic chromium-rich solution by MgO into crystalline chromium for commercial use.

Automated summary

The study aimed to address solid waste management in the leather industry and soil fertility by using potato peel biochar to prepare bio-organic NPK fertilizer. The fertilizer showed positive effects on crop growth and chlorophyll content, and released more ammonia into the soil compared to chemical fertilizers. The study also found no hazardous impact on soil from the use of the bio-organic NPK fertilizer.