EUBCE 2024 - Neha SHUKLA - Production of Artificial Fertilizer (struvite) from Hydrothermal Liquified Char

Production of Artificial Fertilizer (struvite) from Hydrothermal Liquified Char

Short Introductive summary

Phosphorus (P) recovery as struvite (NH4MgPO4.6H2O) from sewage sludge has attracted considerable attention due to its potential to be re-used as fertilizer through P recovery. This study investigated an effective P recovery from hydrothermally liquified sewage sludge char (HTL char) via struvite precipitation after extraction using inorganic and organic acids. The optimum operating conditions for maximum P extraction (94 %) were suggested as 0.7 M of acid strength (H2SO4) and 6.5 h of extraction time. Addition of citric acid (CA) during the struvite precipitation from acid-leached P solution was found beneficial as it improved the struvite purity from 36.6% to 54%. Furthermore, Fourier-transform infrared spectroscopy (FTIR) analysis validated the formation of struvite with the availability of functional groups similar to that of commercial struvite. Upon comparison with the EU fertilizer’s regulations, HTL char struvite was found beneficial as it showed low heavy metal content. Thus, instead of direct land application of sewage sludge, harvested struvite from HTL char could be directly used as a fertilizer with negligible environmental risk.

N. Shukla, Aarhus University, DENMARK
P. Biller, Aarhus University, DENMARK