title: Laboratory experiments on simultaneous removal of K and P from synthetic and real urine for nutrient recycle by crystallization of magnesium-potassium-phosphate-hexahydrate in a draft tube and baffle reactor.
abstract: The simultaneous removal of K and P from urine for nutrient recycling by crystallization of magnesium potassium phosphate hexahydrate (MPP) in a laboratory-scale draft tube and baffle reactor (DTBR) is investigated. Results show that mixing speed and hydraulic retention time are important operating factors that influence crystallization and crystal settlement. Slurry should be discharged at a crystal retention time of 11 h to maintain fluidity in the reactor. Further applications of the DTBR using real urine (pretreated by ammonia stripping and diluted five times) showed that 76% K and 68% P were recycled to multi-nutrient products. The crystals collected were characterized and confirmed mainly as a mixture of magnesium ammonium phosphate hexahydrate, MPP, and magnesium sodium phosphate heptahydrate. Results indicate that the DTBR effectively achieved the simultaneous recycling of K and P from urine to multi-nutrient products through MPP crystallization.
authors.affiliation: School of Environment, Tsinghua University, Beijing, PR China.
authors.forename: Kangning
authors.initials: K
authors.lastname: Xu
authors.forename: Chengwen
authors.initials: C
authors.lastname: Wang
authors.forename: Xiaoxue
authors.initials: X
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Qian
mesh_terms: D011232:Chemical Precipitation; D008274:Magnesium / Q000737:chemistry; D017616:Magnesium Compounds / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry; D011188:Potassium / Q000737:chemistry; D059027:Recycling; D000069877:Struvite; D014556:Urine / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D010710:Phosphates; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D000069877:Struvite; D008274:Magnesium; D011188:Potassium