US 11,999,642 B2
Method for removing calcium ions from high concentration organic wastewater
Pinjing He, Shanghai (CN); Junjie Qiu, Shanghai (CN); Liming Shao, Shanghai (CN); Fan Lyu, Shanghai (CN); and Hua Zhang, Shanghai (CN)
Assigned to TONGJI UNIVERSITY, Shanghai (CN)
Appl. No. 17/264,304
Filed by TONGJI UNIVERSITY, Shanghai (CN)
PCT Filed Nov. 25, 2019, PCT No. PCT/CN2019/120745
§ 371(c)(1), (2) Date Jan. 29, 2021,
PCT Pub. No. WO2021/047059, PCT Pub. Date Mar. 18, 2021.
Claims priority of application No. 201910855454.X (CN), filed on Sep. 10, 2019.
Prior Publication US 2022/0009808 A1, Jan. 13, 2022
Int. Cl. C02F 5/02 (2023.01); C02F 1/52 (2023.01); C02F 101/10 (2006.01)
CPC C02F 5/02 (2013.01) [C02F 1/52 (2013.01); C02F 2001/5218 (2013.01); C02F 2101/10 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method for removing calcium ions from high concentration organic wastewater, wherein the method comprises the steps of:
(1) introducing inorganic carbon, a seed crystal and high concentration organic wastewater containing Ca2+ into a reactor,
wherein a molar ratio of Ca2+ to inorganic carbon is 1:(3.2-6.2),
wherein the seed crystal in step (1) is biomass with negative potential on a surface, and a particle size of the seed crystal is 0.2 μm-2 mm;
(2) adjusting a hydrogen ion activity α(H+) and ionic strength of the solution in the reactors,
wherein the α(H+) in step (2) is adjusted to 3.16×10−12-6.31×10−9 mol/L, and
the ionic strength after adjusting in step (2) is in a range of 0.3-2 mol/L;
(3) sequentially stirring and precipitating in the reactor to convert Ca2+ in the high concentration organic wastewater into calcium carbonate which is then precipitated for calcium removal,
wherein the precipitating step is followed after the stirring step is stopped.