Study of the recovery of phosphorus from struvite precipitation in supernatant line from anaerobic digesters of sludge.
The goal of this work was to study the effective recovery of phosphorus from the supernatant of anaerobic digestion of sewage sludge by precipitation as struvite. The formation of struvite is envisioned as a promising process for nutrient removal and subsequent recovery, thus providing a strong incentive for its implementation, since the sewage is a renewable source of phosphorus. Struvite precipitation was obtained by controlled addition of Mg(OH)2 or MgCl2. We evaluated the removal of ammonia and phosphate under equimolar conditions of magnesium and magnesium stoichiometric excess of 100 to 200% relative to the limiting reagent, under a stirring speed of 300 rpm at pH 8, 9 and 10. The best condition was MgCl2 in 1:1 molar ratio to phosphate, considering the stoichiometric ratio [PO4(3-)]:[NH4(+)] of 0.13 (presented by raw sample). The results show the best cost-benefit ratio, removal of phosphate of 90.6% and ammonium removal of 29%, resulting in 23 mg l(-1) PO4(3-) and 265 mg l(-1) NH4(+) concentration in effluent.
Laboratório de Tratamento de Águas e Reuso de Efluentes (LabTare), Escola de Química, UFRJ, Cidade Universitária, Centro de Tecnologia, Bl. I, Sl. 124, Ilha do Fundão, 21941-909, Rio de Janeiro, Brazil E-mail: ldx1982@poli.ufrj.br.
Luciano Dias
LD
Xavier
Departamento de Engenharia Bioquímica, Escola de Química, UFRJ, Cidade Universitária, Centro de Tecnologia, Bl. E, Sl. 203, Ilha do Fundão, Rio de Janeiro, Brazil.
Magali Christe
MC
Cammarota
Departamento de Processos Inorgânicos, Escola de Química, UFRJ, Cidade Universitária, Centro de Tecnologia, Bl. E, Sl. 206, Ilha do Fundão, Rio de Janeiro, Brazil.
Lídia
L
Yokoyama
Departamento de Recursos Hídricos e Meio Ambiente, Escola Politécnica, UFRJ, Cidade Universitária, Centro de Tecnologia, Bl. D, Sl. 204, Ilha do Fundão, Rio de Janeiro, Brazil.
Isaac
I
Volschan Junior
D000693:Anaerobiosis; D011232:Chemical Precipitation; D015636:Magnesium Chloride / Q000737:chemistry*; D017616:Magnesium Compounds / Q000737:chemistry*; D008276:Magnesium Hydroxide / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D010758:Phosphorus / Q000302:isolation & purification*; D012722:Sewage / Q000737:chemistry*; D000069877:Struvite
D017616:Magnesium Compounds; D010710:Phosphates; D012722:Sewage; D015636:Magnesium Chloride; D010758:Phosphorus; D000069877:Struvite; D008276:Magnesium Hydroxide