HJ 505-2009Water quality. Determination of biochemical oxygen demand after 5 days(BOD5) for dilution and seeding method (English PDF)

4.3 Salt solution

4.3.1 Phosphate buffer solution. 8.5 g potassium dihydrogen phosphate (KH2PO4), 21.8 g dipotassium hydrogen phosphate (K2HPO4), 33.4 g heptahydrate Disodium hydrogen phosphate (Na2HPO4·7H2O) and 1.7 g ammonium chloride (NH4Cl) are dissolved in water and diluted to 1 000 ml. This solution is in 0~4 °C can be stored for 6 months. This solution has a pH of 7.2.

4.3.2 Magnesium Sulfate Solution, rho (MgSO4) = 11.0 g/L. Dissolve 22.5 g of magnesium sulfate heptahydrate (MgSO4·7H2O) in water and dilute to 1 000 ml, this solution can be stored stably for 0 months at 0 to 4 ° C. If any precipitation or microbial growth is found, it should be discarded.

4.3.3 Calcium chloride solution, rho (CaCl2) = 27.6 g/L. Dissolve 27.6 g of anhydrous calcium chloride (CaCl2) in water and dilute to 1 000 ml.

This solution can be stored stably for 0 months at 0 to 4 ° C. If any precipitation or microbial growth is found, it should be discarded.

4.3.4 ferric chloride solution, rho (FeCl3) = 0.15 g/L. dissolve 0.25 g of ferric chloride hexahydrate (FeCl3 · 6H2O) in water, dilute to 1 000 ml, this solution can be stored stably for 0 months at 0~4 °C. If any sediment or microbial growth is found, it should be discarded.

4.4 Dilution water. Add a certain amount of water to a glass bottle of 5 to 20 L, control the water temperature at (20 ± 1) °C, and use an aeration device (5.9) to Less aeration for 1 h, so that the dissolved oxygen in the dilution water reaches 8 mg/L or more. Add the above four salt solutions (4.3) per liter of water before use.

Ml, mix and store at 20 °C. Prevent contamination during aeration, especially to prevent the introduction of organic matter, metals, oxides or reducing substances.

The mass concentration of oxygen in the diluted water should not be supersaturated. It should be placed for 1 h before use and should be used within 24 h. The remaining dilution water should Discard.

4.5 Inoculation of dilution water. According to the source of the inoculum, add appropriate amount of inoculum per liter of dilution water (4.4) (4.2). urban pollution Water and sewage treatment plant effluent plus 1 ~ 10 ml, river or lake water plus 10 ~ 100 ml, inoculated dilution water stored in (20 ± 1) ° C environment in the day, it will be used on the same day. The pH of the inoculated dilution water is 7.2 and the BOD5 should be less than 1.5 mg/L.

4.6 Hydrochloric acid solution, c (HCl) = 0.5 mol/L. Dissolve 40 ml of concentrated hydrochloric acid (HCl) in water and dilute to 1 000 ml.

4.7 Sodium hydroxide solution, c (NaOH) = 0.5 mol/L. Dissolve 20 g of sodium hydroxide in water and dilute to 1 000 ml.

4.8 Sodium sulfite solution, c(Na2SO3)=0.025 mol/L. Dissolve 1.575 g of sodium sulfite (Na2SO3) in water and dilute to 1 000 ml.

This solution is unstable and needs to be used now.

4.9 Glucose-glutamic acid standard solution. glucose (C6H12O6, pure grade) and glutamic acid (HOOC-CH2-CH2-CHNH2-COOH, it is dried at 130 ° C for 1 h, and each 150 mg is dissolved in water and diluted to the mark in a 1 000 ml volumetric flask. BOD5 of this solution it is (210±20) mg/L, and it is used now. The solution can also be cryopreserved in small amounts and used immediately after thawing.

4.10 Propylene thiourea nitrate inhibitor, rho (C4H8N2S) = 1.0 g/L. dissolve 0.20 g of propylene thiourea (C4H8N2S) in.200 ml water Mix in medium, store at 4 ° C, this solution can be stored for 14 days.

4.11 Acetic acid solution, 1 1.

4.12 Potassium iodide solution, rho (KI) = 100 g/L. Dissolve 10 g of potassium iodide (KI) in water and dilute to 100 ml.

4.13 Starch solution, rho = 5 g/L. Dissolve 0.50 g of starch in water and dilute to 100 ml.

6.1 Acquisition and preservation

Sample collection is performed in accordance with the relevant regulations of HJ/T 91.

The collected sample should be filled and sealed in a brown glass bottle with a sample volume of not less than 1 000 ml and transported and stored in a dark place at 0 to 4 °C.

And analyze it as soon as possible within 24 hours. Cannot be analyzed within 24 h, can be stored frozen (avoid sample bottle rupture during cryopreservation), before freezing sample analysis Thaw, homogenize and inoculate.

6.2 Sample pretreatment

6.2.1 PH adjustment

If the sample or diluted sample pH is not in the range of 6 to 8, adjust it with hydrochloric acid solution (4.6) or sodium hydroxide solution (4.7).

The pH is from 6 to 8.

6.2.2 Removal of residual chlorine and combined chlorine

If the sample contains a small amount of residual chlorine, it is usually placed for 1 to 2 hours after sampling, and the free chlorine disappears. For those that cannot disappear in a short time Chlorine, an appropriate amount of sodium sulfite solution can be added to remove the residual chlorine and combined chlorine present in the sample. The amount of sodium sulfite solution added is determined by the following method.

set.

Take 100 ml of the neutralized water sample, add 10 ml of acetic acid solution (4.11), 1 ml of potassium iodide solution (4.12), mix, and immerse in the dark.

Set for 5 min. The precipitated iodine was titrated to a pale yellow color with a sodium sulfite solution, and a 1 ml starch solution (4.13) was added in a blue color. Continue to titrate until Blue has just faded, that is, the end point, record the volume of sodium sulfite solution used, the volume consumed by the sodium sulfite solution, calculate the water sample the volume of sodium sulfite solution.

6.2.3 Sample homogenization

Samples containing large amounts of particulate matter, requiring large dilutions or cryopreserved samples should be stirred evenly before measurement.

6.2.4 Algae in the sample

If a large amount of algae is present in the sample, the determination of BOD5 will be high. When the accuracy of the analysis results is high, the filter is applied before the measurement.

The wells were filtered through a 1.6 µm filter (5.1) and the size of the filter pores was noted in the test report.

6.2.5 Samples with low salt content

If the salt content of the sample is low and the conductivity of the undiluted sample is less than 125 µS/cm, add an appropriate amount of the same volume of the four salt solutions (4.3).

The conductivity of the sample was made greater than 125 µS/cm. The volume V of each salt to be added per liter of sample is calculated according to formula (1).

( 12.8)/113V K .6= delta - (1) where. V--the volume of each salt to be added, ml;

deltaK--The sample requires an increased conductivity value, µS/cm.

7.1 Non-dilution method

The non-dilution method is divided into two cases. non-dilution method and non-dilution method.

If the content of organic matter in the sample is small, the mass concentration of BOD5 is not more than 6 mg/L, and there are enough microorganisms in the sample.

Method of determination. If the amount of organic matter in the sample is small, the mass concentration of BOD5 is not more than 6 mg/L, but there is not enough microorganism in the sample.

For example, acidic wastewater, alkaline wastewater, high-temperature wastewater, cryopreserved wastewater, or chlorinated wastewater are measured by non-dilution inoculation.

7.1.1 Preparation of samples

7.1.1.1 Samples to be tested

Before the measurement, the temperature of the sample to be tested reaches (20±2) °C. If the dissolved oxygen concentration in the sample is low, it needs to be aerated with aeration device (5.9).

15 min, shake thoroughly to remove the air bubbles remaining in the sample; if the oxygen in the sample is supersaturated, fill the container with 2/3 volume and shake vigorously the saturated oxygen is driven out, and the determination method is determined according to the microbial content in the sample. Non-dilution method can be directly sampled; non-dilution vaccination Method, add appropriate amount of inoculum (4.2) per liter of sample, to be determined. If the sample contains nitrifying bacteria, nitrification may occur.

2 ml of propylene thiourea nitrate inhibitor (4.10) was added to each liter of sample.

7.1.1.2 Blank specimen

In the non-dilution inoculation method, add the same amount of inoculum (4.2) as the blank sample per liter of diluted water, and test each liter if necessary.

2 ml of propylene thiourea nitrate inhibitor (4.10) was added to the sample.

7.1.2 Determination of samples

7.1.2.1 Determination of dissolved oxygen in samples by iodometric method

Fill the sample (7.1.1.1) with two dissolved oxygen bottles (5.2) to make the sample overflow a small amount to prevent the dissolved oxygen concentration in the sample from changing.

Change, so that the bubbles present in the bottle are discharged through the wall of the bottle. Put a bottle cap on the bottle, add a water seal, and put a sealing cover on the cap cover to prevent culture.

During the period, the water-sealed water is evaporated and dried. After incubating for 5d ± 4 h or (2 5) d ± 4 h in a constant temperature incubator (5.8), the dissolved oxygen in the sample is determined to be rich.

degree. The mass concentration of dissolved oxygen in the sample before the culture was measured 15 minutes after the other bottle.

The dissolved oxygen was measured in accordance with GB/T 7489.

7.1.2.2 Determination of dissolved oxygen in samples by electrochemical probe method

Fill the sample (7.1.1.1) with a dissolved oxygen bottle (5.2) to make the sample overflow a small amount to prevent the dissolved oxygen concentration in the sample from changing.

Change, so that the bubbles present in the bottle are discharged through the wall of the bottle. The mass concentration of dissolved oxygen in the sample before the culture was measured.

Cover the cap to prevent residual air bubbles in the sample, plus a water seal, and a sealing cover on the cap cover to prevent the water seal water from evaporating during the culture.

dry. Place the vial in a constant temperature incubator (5.8) for 5 d ± 4 h or (2 5) d ± 4 h. Determine the quality of dissolved oxygen in the sample after culture concentration.

The determination of dissolved oxygen is carried out in accordance with GB/T 11913.

Blank samples are measured in the same way as 7.1.2.1 or 7.1.2.2.

7.2 Dilution and inoculation

The dilution and inoculation methods are divided into two cases. dilution method and dilution inoculation method.

If the content of organic matter in the sample is large, the mass concentration of BOD5 is greater than 6 mg/L, and there are enough microorganisms in the sample to be diluted.

Method determination; if the content of organic matter in the sample is large, the mass concentration of BOD5 is greater than 6 mg/L, but there is not enough microorganism in the sample, Determined by dilution inoculation method.

7.2.1 Preparation of samples

7.2.1.1 Samples to be tested

The temperature of the sample to be tested reaches (20±2) °C. If the dissolved oxygen concentration in the sample is low, it needs to be aerated for 15 min with aeration device (5.9).

Shake off the residual air bubbles in the sample; if the oxygen in the sample is supersaturated, fill the 2/3 volume of the container with the sample and force it to shake out the fullness.

And oxygen, and then determine the method based on the microbial content of the sample. Determined by the dilution method, the dilution factor is determined according to the methods in Table 1 and Table 2, it was then diluted with dilution water (4.4). The sample was diluted by inoculating dilution water (4.5) as determined by dilution inoculation. If the sample contains nitrifying bacteria, Nitrification may occur, and 2 ml of propylene thiourea nitrate inhibitor (4.10) should be added to each liter of the culture solution.

Determination of dilution factor. The degree of dilution of the sample should be such that the dissolved oxygen concentration is not less than 2 mg/L, and remains in the sample after culture.

The dissolved oxygen mass concentration is not less than 2 mg/L, and the mass concentration of dissolved oxygen remaining in the sample is preferably 1/3 to 2/3 of the starting concentration.

The dilution factor can be determined from the total organic carbon (TOC), permanganate index (IMn) or chemical oxygen demand (CODCr) of the sample.

Estimate the ratio of BOD5 to total organic carbon (TOC), permanganate index (IMn) or chemical oxygen demand (CODCr) according to Table 1.

The expected value of BOD5 (R is related to the type of sample), and then the dilution factor is determined according to Table 2. When the dilution factor cannot be accurately selected, One sample is made in 2 to 3 different dilution factors.

Table 1 Typical ratio R

Type of water sample total organic carbon R (BOD5/T OC) Permanganate index R (BOD5/IMn) Chemical oxygen demand R (BOD5/CODCr) Untreated wastewater 1.2~2.8 1.2~1.5 0.35~0.65 Biochemical treatment of wastewater 0.3~1.0 0.5~1.2 0.20~0.35 Calculate the expected value of BOD5 according to equation (2) by selecting the appropriate R value in Table 1.

R Yrho = · (2)

Where. rho -- the expected value of the five-day biochemical oxygen demand concentration, mg/L;

Y--Total organic carbon (TOC), permangana...