Pyrolysis of sewage sludge (SS) enriched the phosphorus (P) content in biochar but reduced the amount of available P (AP) content. Therefore, modification of SS is necessary before pyrolysis to increase the availability of P. Pyrolysis of dried and ground SS was done with potassium (K) salts - potassium acetate (CH3COOK), potassium citrate monohydrate (C6H5K3O7), potassium chloride (KCl) and potassium bicarbonate (KHCO3). Sewage sludge biochar (SSB) was produced at 500 and 600 °C. SS doped with 5% K as K-acetate, K-citrate and K-bicarbonate had the highest AP content, Ì´ 25% more than the undoped sewage sludge biochar (SSB) produced at 600 °C. 
P leaching experiments were conducted for 90 days with 5% K doped SSB with K-acetate and K-citrate which was 4.5 times and  times faster in K-doped SSB than undoped SSB produced at 500 and 600 °C respectively. Xray diffraction (Xrd), SEM-EDS and FTIR was done for further characterization of the modified and unmodified SSB.