US 11,753,319 B2
Method for intensification of advanced biological nitrogen removal and reduction of endocrine disrupting toxicity
Hui Huang, Nanjing (CN); Lili Jin, Nanjing (CN); Jun Hu, Nanjing (CN); and Hongqiang Ren, Nanjing (CN)
Assigned to NANJING UNIVERSITY, Nanjing (CN)
Filed by NANJING UNIVERSITY, Nanjing (CN)
Filed on Feb. 28, 2023, as Appl. No. 18/115,014.
Prior Publication US 2023/0202887 A1, Jun. 29, 2023
Int. Cl. C02F 1/72 (2023.01); B01J 20/04 (2006.01); B01J 20/26 (2006.01); B01J 20/32 (2006.01); C02F 1/28 (2023.01); C02F 1/463 (2023.01); C02F 3/28 (2023.01); C02F 9/00 (2023.01); C02F 1/00 (2023.01); C02F 101/30 (2006.01)
CPC C02F 1/722 (2013.01) [B01J 20/04 (2013.01); B01J 20/267 (2013.01); B01J 20/32 (2013.01); C02F 1/288 (2013.01); C02F 1/463 (2013.01); C02F 3/28 (2013.01); C02F 9/00 (2013.01); C02F 1/00 (2013.01); C02F 2101/305 (2013.01); C02F 2305/02 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method for biological denitrification enhancement and toxicity reduction, comprising the following steps:
S1: preparing sustained-release calcium peroxide nanoparticles (SR-nCPs) by carrying the following steps S1-1 to S1-5:
S1-1: adding calcium sulfate powder to deionized water and dispersing evenly, then adding 1 M of a potassium hydroxide solution to the deionized water to prepare an alkaline suspension containing the calcium sulfate powder, wherein a mass ratio of the calcium sulfate to the deionized water is 1:5-15, and a volume ratio of the potassium hydroxide solution to the deionized water is 1:1-5;
S1-2: using a mechanical stirrer to stir the above alkaline suspension at room temperature, adding a hydrogen peroxide solution with a mass fraction of 30% to the alkaline suspension, letting the suspension stand to react for 2 h and generate a precipitate, wherein a molar ratio of the hydrogen peroxide to the calcium sulfate in the suspension is 1:5-10;
S1-3: first washing the above precipitate with deionized water for three times, then washing with absolute ethanol for three times, drying under the condition of 60-80° C. for 24-48 h to obtain nano-calcium peroxide (n-CP) oxygen-releasing materials and storing the materials in a sealed and dry environment for subsequent use;
S1-4: adding polyvinyl alcohol, sodium carboxymethyl cellulose and stearic acid to deionized water, heating under the condition of 90-100° C. for 2-3 h to obtain a colloidal substance, then adding the n-CP oxygen-releasing materials and quartz sand to the colloidal substance, and mixing and stirring them evenly to obtain a mixed colloidal substance;
S1-5: adding the mixed colloidal substance to a spherical silicone mold, putting the spherical mold under the condition of −80-−20° C. for freezing crosslinking for 12-16 h, then thawing and freezing again, repeating process of thawing and freezing for multiple times, and obtaining frozen crosslinked spherical particles; adding the frozen crosslinked spherical particles into a saturated boric acid solution containing 3-6% of CaCl2 by weight for chemically crosslinking for 12-16 h, and drying under the condition of 60-80° C. for 24-48 h to obtain SR-nCPs;
S2: constructing various SR-nCP layers in bioreactors for wastewaters with various properties by adding a certain amount of the SR-nCPs in one of the bioreactors corresponding to wastewater with a certain property; and
S3: adding a biofilm into a bioreactor with a SR-nCP layer and culturing the biofilm by adopting an inoculation biofilm culturing method or a natural biofilm culturing method, and introducing the wastewater into the bioreactor for reaction to form an effluent;
wherein the bioreactor is an anoxic bioreactor or an anaerobic bioreactor.