Nitrification rateThe efficiency of ammonia nitrogen being oxidized by microorganisms to nitrate nitrogen per unit time is a key indicator for measuring the intensity of nitrification in water or soil. The determination principle is based on the oxidation reaction of ammonia nitrogen gradually converted into nitrite nitrogen and nitrate nitrogen under the action of ammonia oxidizing bacteria and nitrite oxidizing bacteria. By monitoring the decrease in ammonia nitrogen concentration or the increase in nitrate nitrogen concentration during this process, the nitrification rate can be calculated.

　　Nitrification rateCommon measurement methods:

Concentration variation method

Step: Analyze the ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the sewage, and calculate the nitrification rate per unit time based on the time variation of the total amount of nitrite nitrogen and nitrate nitrogen.

Formula: Nitrification rate per unit volume of activated sludge mixture (mg/L · hour)=increase in nitrite nitrogen concentration (mg/L)+increase in nitrate nitrogen concentration (mg/L)/elapsed time (hours).

Curve slope method

Steps:

Pour an appropriate amount of influent (such as 1L) and aerobic terminal activated sludge (such as 1L) into the reactor, and aerate the reactor.

Start timing and take a water sample to measure the initial ammonia nitrogen concentration (the initial ammonia nitrogen concentration should be controlled below 50mg/L).

Samples were taken and filtered at different time points during the experiment (such as 5 minutes, 10 minutes, 15 minutes, etc.) to measure the concentration of ammonia nitrogen for a certain period of time (such as 3 hours).

Draw a curve of ammonia nitrogen concentration versus time, then derive a trend line from the curve, and calculate the nitrification rate based on the slope of the line.

Formula: Nitrification rate=slope of the line x 60 x 24 (unit: gNH3-N/(gMLVSS · d) or other corresponding units, depending on the slope unit and time conversion).

Simple qualitative experimental method

Purpose: To determine whether the nitrification reaction in the activated sludge of the sewage plant has been severely impacted, and whether the system has the ability to recover in the event of an impact.

Steps:

Compare the real-time inflow of 5-10L in the factory with the reflux sludge of 5-10L in the biochemical system of the surrounding sewage with normal nitrification.

Prepare two identical models of oxygenation pumps or oxygenation pumps with two aeration heads, as well as two 2L beakers in the laboratory.

Take 1L each of the inflow and reflux activated sludge from the factory, mix them in a 1:1 ratio, and inject them into a beaker labeled "Factory Sludge"; Take 1L of the incoming water from the factory and 1L of the normally returning activated sludge from the surrounding factory, mix them in a 1:1 ratio, and inject them into a beaker labeled "sludge from the surrounding factory".

Place the aeration heads of the two oxygenation pumps in two beakers, power on to start aeration, and record the start time of aeration.

Detect the ammonia nitrogen value of the incoming water in the factory, and filter the mixed solution in two beakers after initial aeration, 1, 2, 4, 6, and 8 hours for ammonia nitrogen value detection.

Record and analyze the ammonia nitrogen detection values, compare the ammonia nitrogen removal of "in plant sludge" and "surrounding in plant sludge", and determine the next process adjustment measures based on the comparison results.