Phosphorus recovery from wastewater and sludge

Abstract

Wastewater and sludge are potential resource of phosphorus (P) for fertilizer production. One method of recovering phosphorus is via chemical precipitation. In the study, phosphorus was recovered from wastewater and sludge. First, hydrolysis was carried out to release the phosphorus in the sludge by the addition of 1.0M acid (sulfuric acid) or base (sodium hydroxide) solution mixed for three hours at 200 rpm. The hydrolyzed sludge was filtered, and the pH of the solution was adjusted to 9.0. Precipitation for both wastewater and hydrolyzed sludge solution was carried out using magnesium chloride hexahydrate (MgCl2•6H2O) and ammonium chloride (NH4Cl). The mixture was stirred for an hour for crystallization. Precipitates were allowed to settle for 24 hours before it was filtered and dried in an oven at 55-58oC for 24 hours. The dried sample was grinded and characterized using Fourier transform infrared spectroscopy (FTIR), x-ray fluorenscence (XRF), and scanning electron microscope with energy-dispersive x-ray spectroscopy(SEM-EDX).

Pyrolysis of Municipal Sewage Sludge for Biofuel Production: A Review

“…80,81 Another way would be to combust or gasify the pyrolysis char, and the P would be recovered from the ash by precipitation of struvite (MgNH 4 PO 4 •6H 2 O) which is reported to be an alternative to commercial fertilizer owing to its advantages. 82 In addition, this char has been found to be an affordable catalyst for soil amendment. 3,4,27,58 It is also applicable to heavy metal and organic pollutant adsorption.…”

“…In fact, the various metal in the sewage sludge feedstock will lead to a mixture of P-metal complexes including Fe–P, Al–P, and Ca–P, in the pyrolysis char. Thus, chemical leaching, using acid or alkaline solutions that have the ability to release these P-metal complexes, is reported as a route for P recovery from high P pyrolysis char. , Another way would be to combust or gasify the pyrolysis char, and the P would be recovered from the ash by precipitation of struvite (MgNH 4 PO 4 ·6H 2 O) which is reported to be an alternative to commercial fertilizer owing to its advantages . In addition, this char has been found to be an affordable catalyst for soil amendment. ,,, It is also applicable to heavy metal and organic pollutant adsorption …”