Method of measuring concentration of dissolved organic nitrogen in sewage

Patent metadata

Field	Value
Publication number	US-11014835-B2
Application number	US-202016902213-A
Country	US
Kind code	B2
Filing date	Jun 15, 2020
Priority date	Jan 20, 2017
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A method of measuring concentration of dissolved organic nitrogen in sewage. The method includes: filtering a sewage sample using a filter membrane; measuring the concentrations of total dissolved nitrogen (TDN), ammonia nitrogen (NH4+), and nitric nitrogen (NO3−) in the sewage sample, respectively designated as CTDN(I), CNH4+(I) and CNO3−(I); calculating the ratios of (CNH4+(I)+CNO3−(I))/CTDN(I) and CNO3−(I)/CNH4+(I), and according to the ratios, calculating the concentration of dissolved organic nitrogen (DON) in the sewage sample.

First claim

What is claimed is:

1. A method of measuring a concentration of dissolved organic nitrogen in sewage, the method comprising:
(1) extracting a sewage sample from an anaerobic stage or an aerobic stage of a wastewater treatment plant and filtering the sewage sample using a filter membrane to obtain a filtered sewage sample;
(2) measuring concentrations of total dissolved nitrogen (TDN), ammonia nitrogen (NH 4 + ), and nitric nitrogen (NO 3 − ) in the filtered sewage sample, respectively designated as C TDN(I) , C NH4 + (I) and C NO3 − (I) ; and
(3) when (C NH4 + (I) +C NO3 − (I) )/C TDN(I) ≥0.7 and C NO3 − (I) /C NH4 + (I) <1, dialyzing the filtered sewage sample in a suspended dialysis bag for between 34 and 38 hours to obtain a dialyzed sewage sample, and measuring concentrations of total dissolved nitrogen (TDN), ammonia nitrogen (NH 4 + ), nitric nitrogen (NO 3 − ) and nitrite nitrogen (NO 2 − ) in the dialyzed sewage sample, respectively designated as C TDN(III) , C NH4 + (III) , C NO3 − (III) , and C NO2 − (III) , and obtaining a concentration of dissolved organic nitrogen (DON) in the sewage sample as follows: DON=C TDN(III) —C NH4 + (III) —C NO3 − (III) —C NO2 − (III) ;

wherein:
the suspended dialysis bag is a cellulose ester membrane;
the suspended dialysis bag is hydrophilic; and
the suspended dialysis bag has a molecular weight cut-off (MWCO) of 100-500 Da, and a hydraulic retention time of a dialysate in the sewage sample is 4 h.

2. The method of claim 1 , wherein the filter membrane has a pore size of 0.45 μm.

3. The method of claim 1 , wherein the concentrations of the total dissolved nitrogen (TDN), ammonia nitrogen (NH 4 + ), nitric nitrogen (NO 3 − ) and nitrite nitrogen (NO 2 − ) are measured using potassium persulfate oxidation-ion chromatography, salicylic acid-hypochlorite spectrophotometry, ion chromatography and N-(1-naphthyl)-ethylenediamine spectrophotometry, respectively.

Assignees

• Nanjing University Of Technology

Inventors

• Ren Hongqiang
• Hu Haidong
• Geng Jinju
• Ding Lili
• Huang Hui

Classifications

• C02F2209/003

  Downstream control, i.e. outlet monitoring, e.g. to check the treating agents, such as halogens or ozone, leaving the process · CPC title

• C02F2209/16

  Total nitrogen (tkN-N) · CPC title

• C02F3/305 Primary

  characterised by the denitrification · CPC title

• C02F1/447 Primary

  by membrane distillation (distillation and evaporation without the use of membranes C02F1/04) · CPC title