Firstly, 50 ml of activated sludge samples were taken out of the reactor, and centrifuged at 2000 g for 65438 05 minutes at room temperature, and then the supernatant was poured out. After centrifugation, 526mg? L- 1 NaCl，74.56mg？ L- 1KCl，760.2mg？ L- 1Na3PO4 and 552mg? L- 1NaH2PO4 phosphate buffer, so that it is suspended in liquid state again. Then transfer the suspended sludge sample to a beaker and add 90g? GMLVSS- 1 ion exchange resin (732 cation exchange resin) and stirred at 600rpm for 2 hours to mix them. After mixing, 4000g was centrifuged for 300 minutes to remove resin and organic matter, and the supernatant was EPS extract.
(2) Analysis method of extracellular polymers EPS extract mainly contains polysaccharide, protein and DNA. The polysaccharide was determined by anthrone-sulfuric acid colorimetry []. That is, sugars will be dehydrated by H2SO4 at high temperature to generate furfural or furfural derivatives, which will condense with anthrone (C 14 10O) to generate blue compounds. The absorbance (72 1 spectrophotometer) was measured at 620nm, and the content of polysaccharide could be converted from the standard curve of glucose.
Protein was determined by ultraviolet absorption method, and the absorbance at 260nm and 280nm was also determined. The concentration of protein is calculated by the following formula (mg? ML- 1): ρ protein =1.45× A280 nm-0.74× A260 nm. This method can eliminate the interference of sample neutralization calculation. The content of EPS is ultimately based on the total amount of each component in the unit mass of MLVSS.
The modified Brunk method was used for DNA determination. The main reagents were: 0.2 ppm DAPI reagent (4,6-diimide -2- phenylindole), 10 mM EDTA, 10 mM TRIS, pH 7. Steps: change to 100? Put 1 l EPS extract into a test tube with a pipette, and add 2.5 ml of the above reagent. The sample (excitation wavelength 360nm, emission wavelength 450 nm) was determined directly, and the standard method was used in salmon experiment.