Hydrocyclone separation of activated sludge and inorganic ash in the biological tank treating high hardness wastewater
LIU Yi1,2,, HAN Yafang1,2, XU Weinan2,3, JI Zongyi1,2, WANG Hualin1,2, ZHANG Yanhong2,3,, 1.School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China 2.National Engineering Laboratory for Industrial Wastewater Treatment, Shanghai 200237, China 3.School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China
Abstract:The generated inorganic ash in biological reactor treating high hardness wastewater decreased the activity and settleability of activated sludge. Hydrocyclone application was expected to in-situ separate the inorganic ash from the activated sludge and increase its biological treatment efficiency. The attachment pattern and separation efficiency between inorganic ash and activated sludge were investigated by offline and online experiments, as well as the effect of inorganic ash removal on the biological treatment efficiency of simulated high hardness wastewater. The results showed that the organics ratio decreased from 0.75 in SBR reactor without calcium ion to 0.39 with influent calcium ion concentration of 2 400 mg·L?1 after 150 d continuous biological treatment of 6 groups of influent with different Ca2+ concentrations, COD and NH4-N removal efficiencies also decreased by 11% and 60%, respectively. The atomic force microscope (AFM) images illustrated that the generated inorganic ash increased the surface roughness of activated sludge from 20.5 nm for Ca2+-free influent to 38.2 nm for Ca2+-containing influent. The surface-attached inorganic ash can be removed from the activated sludge by centrifuge. The mixture of inorganic ash and activated sludge in SBR with influent calcium ion concentration of 800 mg·L?1 was circularly separated for 10 times by hydrocyclone with the optimum structure, and the organics ratio in SBR increased from 0.17 to 0.37. The side-flow hydrocyclone separation experiments were conducted for 120 m3·h?1 SBR in a coal-to-hydrogen gasification wastewater treatment plant, three months running caused the increase of the organics ratio from 0.21 in control SBR to 0.45 in modified SBR, the effluent COD and NH4-N decreased by 17.1 mg·L?1 and 14.3 mg·L?1, respectively. The new approach of online hydrocyclone separation conditioning provides a reference for the upgrade of the biological treatment efficiency of high hardness wastewater. Key words:high hardness wastewater/ biological process/ inorganic ash/ hydrocyclone separation/ MLVSS/MLSS.
图1泥灰旋流分离工艺流程 Figure1.Schematic diagram of hydrocyclone separation device
LAY C W, LIU Y, FANE G A. Impacts of salinity on the performance of high retention membrane bioreactors for water reclamation: A review[J]. Water Research, 2010, 44(1): 21-40. doi: 10.1016/j.watres.2009.09.026
[3]
ADAV S S, LEE D J, LAI J Y. Microbial community of acetate utilizing denitrifiers in aerobic granules[J]. Applied Microbiology & Biotechnology, 2010, 85(3): 753.
[4]
SCHMIDT J E, AHRING B K. Granular sludge formation in upflow anaerobic sludge blanket (UASB) reactors[J]. Biotechnology & Bioengineering, 2015, 49(3): 229-246.
[5]
BARAT R, MONTOYA T, BORRAS L, et al. Calcium effect on enhanced biological phosphorus removal[J]. Water Science & Technology, 2006, 53(12): 29-37.
[6]
WAN C L, YANG X, LEE D J, et al. Aerobic granulation of aggregating consortium X9 isolated from aerobic granules and role of cyclic di-GMP[J]. Bioresource Technology, 2014, 152: 557-561. doi: 10.1016/j.biortech.2013.11.052
[7]
WAN C L, YANG X, LEE D J, et al. Partial nitrification of wastewaters with high NaCl concentrations by aerobic granules in continuous-flow reactor[J]. Bioresource Technology, 2014, 152: 1-6. doi: 10.1016/j.biortech.2013.10.112
[8]
LIAO B Q, ALLEN D G, DROPPO I G, et al. Surface properties of sludge and their role in bioflocculation and settleability[J]. Water Research, 2001, 35(2): 339-350. doi: 10.1016/S0043-1354(00)00277-3
[9]
WILEN B M, JIN B, LANT P. The influence of key chemical constituents in activated sludge on surface and flocculating properties[J]. Water Research, 2003, 37(9): 2127-2139. doi: 10.1016/S0043-1354(02)00629-2
KU Y, JUNG I L. Photocatalytic reduction of Cr(VI) in aqueous solutions by UV irradiation with the presence of titanium dioxide[J]. Water Research, 2001, 35(1): 135-142. doi: 10.1016/S0043-1354(00)00098-1
SHENG G P, XU J, LI W H, et al. Quantification of the interactions between Ca2+, Hg2+ and extracellular polymeric substances (EPS) of sludge[J]. Chemosphere, 2013, 93(7): 1436-1441. doi: 10.1016/j.chemosphere.2013.07.076
[16]
HONG L, FANG H. Characterization of electrostatic binding sites of extracellular polymers by linear programming analysis of titration data[J]. Biotechnology & Bioengineering, 2010, 80(7): 806-811.
[17]
SOBECK D C, HIGGINS M J. Examination of three theories for mechanisms of cation-induced bioflocculation[J]. Water Research, 2002, 36(3): 527-538. doi: 10.1016/S0043-1354(01)00254-8
[18]
GUIBAUD G, COMTE S, BORDAS F, et al. Comparison of the complexation potential of extracellular polymeric substances (EPS), extracted from activated sludges and produced by pure bacteria strains, for cadmium, lead and nickel[J]. Chemosphere, 2005, 59(5): 629-638. doi: 10.1016/j.chemosphere.2004.10.028
[19]
WANG Q, LI J, POON C. Novel recycling of phosphorus-recovered incinerated sewage sludge ash residues by co-pyrolysis with lignin for reductive/sorptive removal of hexavalent chromium from aqueous solutions[J]. Chemosphere, 2021, 285: 131434. doi: 10.1016/j.chemosphere.2021.131434
[20]
GAO N, DUAN Y, LI Z, et al. Hydrothermal treatment combined with in-situ mechanical compression for floated oily sludge dewatering[J]. Journal of Hazardous Materials, 2021, 402: 124173. doi: 10.1016/j.jhazmat.2020.124173
[21]
JIA H, LIU B, ZHANG X, et al. Effects of ultrasonic treatment on the pyrolysis characteristics and kinetics of waste activated sludge[J]. Environmental Research, 2020, 183: 109250. doi: 10.1016/j.envres.2020.109250
[22]
HUANG Y, LI J, ZHANG Y, et al. High-speed particle rotation for coating oil removal by hydrocyclone[J]. Separation and Purification Technology, 2017, 177: 263-271. doi: 10.1016/j.seppur.2016.12.001
[23]
ZUBROWSKA-SUDOL M, WALCZAK J. Effects of mechanical disintegration of activated sludge on the activity of nitrifying and denitrifying bacteria and phosphorus accumulating organisms[J]. Water Research, 2014, 61: 200-209. doi: 10.1016/j.watres.2014.05.029
[24]
LIU Y, WANG H, XU X, et al. Achieving enhanced denitrification via hydrocyclone treatment on mixed liquor recirculation in the anoxic/aerobic process[J]. Chemosphere, 2017, 189: 206-212. doi: 10.1016/j.chemosphere.2017.09.056
[25]
APHA. Standard Methods for the Examination of Water and Wastewater, 21th edition[S]. American Public Health Association, 2005, Washington, DC.
[26]
LI H, JIN Y, RASOOL B, et al. Effects of ultrasonic disintegration on sludge microbial activity and dewaterability[J]. Journal of Hazardous Materials, 2019, 161: 1421-1426.
1.School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China 2.National Engineering Laboratory for Industrial Wastewater Treatment, Shanghai 200237, China 3.School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China Received Date: 2021-07-04 Accepted Date: 2021-09-06 Available Online: 2021-11-18 Keywords:high hardness wastewater/ biological process/ inorganic ash/ hydrocyclone separation/ MLVSS/MLSS Abstract:The generated inorganic ash in biological reactor treating high hardness wastewater decreased the activity and settleability of activated sludge. Hydrocyclone application was expected to in-situ separate the inorganic ash from the activated sludge and increase its biological treatment efficiency. The attachment pattern and separation efficiency between inorganic ash and activated sludge were investigated by offline and online experiments, as well as the effect of inorganic ash removal on the biological treatment efficiency of simulated high hardness wastewater. The results showed that the organics ratio decreased from 0.75 in SBR reactor without calcium ion to 0.39 with influent calcium ion concentration of 2 400 mg·L?1 after 150 d continuous biological treatment of 6 groups of influent with different Ca2+ concentrations, COD and NH4-N removal efficiencies also decreased by 11% and 60%, respectively. The atomic force microscope (AFM) images illustrated that the generated inorganic ash increased the surface roughness of activated sludge from 20.5 nm for Ca2+-free influent to 38.2 nm for Ca2+-containing influent. The surface-attached inorganic ash can be removed from the activated sludge by centrifuge. The mixture of inorganic ash and activated sludge in SBR with influent calcium ion concentration of 800 mg·L?1 was circularly separated for 10 times by hydrocyclone with the optimum structure, and the organics ratio in SBR increased from 0.17 to 0.37. The side-flow hydrocyclone separation experiments were conducted for 120 m3·h?1 SBR in a coal-to-hydrogen gasification wastewater treatment plant, three months running caused the increase of the organics ratio from 0.21 in control SBR to 0.45 in modified SBR, the effluent COD and NH4-N decreased by 17.1 mg·L?1 and 14.3 mg·L?1, respectively. The new approach of online hydrocyclone separation conditioning provides a reference for the upgrade of the biological treatment efficiency of high hardness wastewater.