Geometry optimization of struvite crystallization fluidized bed
CAI Jiasheng1,2,, YE Xin1,,, YE Zhilong1, CHEN Shaohua1 1.Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China 2.University of Chinese Academy of Sciences, Beijing 100049, China
Abstract:In view of the uncertainty and complexity in the geometry design of struvite-crystallization fluidized bed reactors, numerical simulation was first adopted to explore the turbulence intensity, classification characteristics and fines entrapment behaviors of fluidized bed reactors with different geometries under multi-particle systems. The simulation results showed that the one-sectional fluidized bed reactor was superior to the multi-sectional and cone-shaped fluidized bed reactor in classifying pellets and turbulent conditions. The fines retention efficiency cannot be significantly improved by installing sedimentation components in the precipitation zone. As for the consequences of experiments, no significant difference of phosphorus removal efficiencies was observed between the one-sectional fluidized bed reactor and the traditional multi-sectional fluidized bed reactor at different influent phosphorus concentrations (240, 480 and 1 000 mg·L?1). It was also proved that the one-section fluidized bed reactor had good capability in granulation, where particles with sizes larger than 1.25 mm took up the percentage of 88.1%, 96.4% and 70.1%, respectively. The experimental results validated that the reliability and rationality of the numerical optimization method. The simplified one-section fluidized bed reactor, which displayed good performance in phosphorus removal and product characteristics, was a promising struvite-crystallization fluidized reactor. Key words:struvite/ one-sectional fluidized bed reactor/ numerical simulation/ phosphorus recovery.
图1不同外部构型/内部构件流化床几何建模及网格划分 Figure1.Geometries and mesh of FBR with different outer shapes and inner modules
SOARES A, VEESAM M, SIMOES F, et al. Bio-struvite: A new route to recover phosphorus from wastewater[J]. Clean-Soil, Air, Water, 2014, 42(7): 994-997. doi: 10.1002/clen.v42.7
[2]
DESMIDT E, GHYSELBRECHT K, ZHANG Y, et al. Global phosphorus scarcity and full-scale P-recovery techniques: A review[J]. Critical Reviews in Environmental Science and Technology, 2014, 45(4): 336-384.
[3]
KRINOVICL E, LEICHTFUSS A R, NAVIZAGA C, et al. Spectroscopic and microscopic identification of the reaction products and intermediates during the struvite (MgNH4PO4·6H2O) formation from magnesium oxide (MgO) and magnesium carbonate (MgCO3) microparticles[J]. ACS Sustainable Chemistry & Engineering, 2017, 5(2): 1567-1577.
[4]
RAHMAN M M, SALLEH M A M, RASHID U, et al. Production of slow release crystal fertilizer from wastewaters through struvite crystallization: A review[J]. Arabian Journal of Chemistry, 2014, 7(1): 139-155. doi: 10.1016/j.arabjc.2013.10.007
[5]
TAO W, FATTAH K P, HUCHZERMEIER M P. Struvite recovery from anaerobically digested dairy manure: A review of application potential and hindrances[J]. Journal of Environmental Management, 2016, 169: 46-57.
ADNAN A, MAVINIC D S, KOCH F A, et al. Pilot-scale study of phosphorus recovery through struvite crystallization: Examining the process feasibility[J]. Journal of Environmental Engineering and Science, 2003, 2(5): 315-324. doi: 10.1139/s03-040
[10]
YE X, YE Z L, LOU Y, et al. A comprehensive understanding of saturation index and upflow velocity in a pilot-scale fluidized bed reactor for struvite recovery from swine wastewater[J]. Powder Technology, 2016, 295: 16-26. doi: 10.1016/j.powtec.2016.03.022
[11]
FATTAH K P, MAVINIC D S, KOCH F A, et al. Determining the feasibility of phosphorus recovery as struvite from filter press centrate in a secondary wastewater treatment plant[J]. Journal of Environmental Science and Health, 2008, 43(7): 756-764. doi: 10.1080/10934520801960052
[12]
BRITTON A, KOCH F A, MAVINIC D S, et al. Pilot-scale struvite recovery from anaerobic digester supernatant at an enhanced biological phosphorus removal wastewater treatment plant[J]. Journal of Environmental Engineering and Science, 2005, 4(4): 265-277. doi: 10.1139/s04-059
[13]
BHUIYAN M I, MAVINIC D S, KOCH F A. Phosphorus recovery from wastewater through struvite formation in fluidized bed reactors: A sustainable approach[J]. Water Science Technology, 2008, 57(2): 175-181. doi: 10.2166/wst.2008.002
[14]
LE CORRE K S, VALSAMI-JONES E, HOBBS P, et al. Struvite crystallisation and recovery using a stainless steel structure as a seed material[J]. Water Research, 2007, 41(11): 2449-2456. doi: 10.1016/j.watres.2007.03.002
[15]
LE CORRE K S, VALSAMI-JONES E, HOBBS P, et al. Agglomeration of struvite crystals[J]. Water Research, 2007, 41(2): 419-425. doi: 10.1016/j.watres.2006.10.025
[16]
YE X, CHU D, LOU Y, et al. Numerical simulation of flow hydrodynamics of struvite pellets in a liquid-solid fluidized bed[J]. Journal of Environmental Sciences, 2017, 57(7): 391-401.
[17]
WANG J, YE X, ZHANG Z, et al. Selection of cost-effective magnesium sources for fluidized struvite crystallization[J]. Journal Environmental Sciences, 2018, 70: 144-153. doi: 10.1016/j.jes.2017.11.029
[18]
FATTAH K P, MAVINIC D S, KOCH F A. Influence of process parameters on the characteristics of struvite pellets[J]. Journal of Environmental Engineering, 2012, 138(12): 1200-1209. doi: 10.1061/(ASCE)EE.1943-7870.0000576
1.Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China 2.University of Chinese Academy of Sciences, Beijing 100049, China Received Date: 2018-12-18 Accepted Date: 2019-05-12 Available Online: 2019-09-17 Keywords:struvite/ one-sectional fluidized bed reactor/ numerical simulation/ phosphorus recovery Abstract:In view of the uncertainty and complexity in the geometry design of struvite-crystallization fluidized bed reactors, numerical simulation was first adopted to explore the turbulence intensity, classification characteristics and fines entrapment behaviors of fluidized bed reactors with different geometries under multi-particle systems. The simulation results showed that the one-sectional fluidized bed reactor was superior to the multi-sectional and cone-shaped fluidized bed reactor in classifying pellets and turbulent conditions. The fines retention efficiency cannot be significantly improved by installing sedimentation components in the precipitation zone. As for the consequences of experiments, no significant difference of phosphorus removal efficiencies was observed between the one-sectional fluidized bed reactor and the traditional multi-sectional fluidized bed reactor at different influent phosphorus concentrations (240, 480 and 1 000 mg·L?1). It was also proved that the one-section fluidized bed reactor had good capability in granulation, where particles with sizes larger than 1.25 mm took up the percentage of 88.1%, 96.4% and 70.1%, respectively. The experimental results validated that the reliability and rationality of the numerical optimization method. The simplified one-section fluidized bed reactor, which displayed good performance in phosphorus removal and product characteristics, was a promising struvite-crystallization fluidized reactor.