Evaluation of biochar amended biosolids co-composting to improve the nutrient transformation and its correlation as a function for the production of nutrient-rich compost

The influence of biochar amended dewatered fresh sewage sludge (DFSS)-wheat straw co-composting on nutrients transformation and end products quality was investigated. This is the first study to examine the biochar applied compost quality with different kgha^-1 TKN on Brassica rapa L. growth. Seven mixtures were composted over 8-weeks period in 130-L reactor using the same DFSS with different concentration of biochar (2%, 4%, 6%, 8%, 12% and 18% on dry weight basis) and without additive added treatment served as control. The results indicated that compost with 8-12% biochar became more humified within 35days of composting, and the compost maturity parameters also showed that this could be much more feasible approach to increased water-soluble nutrients including NO₃, DOC, DON, PO₄^3-, K⁺ and Na⁺, but bioavailability of Cu, Zn, Ni and Pb content reduced as compared to control. Finally, results showed that 8-12% biochar was recommended for DFSS composting and 150kgha^-1 TKN of compost dosages for organic farming.