The effect of heavy metal ions on sludge activity We found a corresponding relationship

Activated sludge suppression test, in fact, we rarely track and rarely do it, mainly because this experiment is not easy to do, sometimes the actual and experimental differences are still very large, we have conducted a study, carried out the following analysis for the reference of your colleagues in sewage troban.

First, throw bricks and lead jade

Activated sludge respiratory inhibition test is actually a national standard, the name of this national standard is called: chemical activated sludge respiratory inhibition test (GB/T 21796-2008), this experiment is actually for all chemicals, such as heavy metal elements, phenols and other substances that have a more obvious inhibitory effect on activated sludge, although it is a national standard, but not a mandatory standard (/T for reference or selective standard), this article is mainly around this national standard for research and writing, And mainly refers to a paper, mainly published by zhao Qingxiang, in Shanghai Environmental Science, February 1993, volume 12, pages 38-40, entitled "Inhibition of biological sludge activity by heavy metal ions", the research and conclusion of this article is also mainly around metal ions, if there is a small partner to check the phenol article, you can refer to the guwen teacher in 2015 in the journal of ecotoxicology published in the journal entitled "7 kinds of phenolic chemicals on the respiratory inhibition effect of activated sludge article", another article is titled " Comparative study of microbial toxicity of heavy metals on activated sludge" article, the author is Li Juanying, Shanghai Ocean University School of Life published in "Environmental Pollution and Prevention" Volume 31 in 2009, interested partners can also take a look, more profound, I did not fully understand.

The results of the activated sludge suppression test are actually very useful, especially in some domestic sewage plants in industrial areas and some industrial sewage plants, which can quickly determine what kind of substance exceeds the standard to cause sludge poisoning, combined with some technical equipment of fluorescent tracer (it seems to remember this) and can quickly find the manufacturer of stealing discharge. However, this method is generally not very important to sewage plants, one is the difficulty of the experiment and the other is the accuracy of the experiment, I will briefly discuss the results of the research.

Second, simple noun explanation

1. Breathing rate

The respiratory rate is characterized by the amount of oxygen consumed by aerobic microorganisms in sludge or sewage per unit time, usually expressed in milligrams of oxygen consumed per liter of sludge or sewage per hour (mg/(L*h)).

2. Half effect concentration (EC50)

In the control group comparison, the concentration of the subject causes a 50% decrease in the rate of microbial respiration.

The results obtained by the following discussion are basically EC50 results, that is, the subject concentration that causes the microbial respiration rate to decrease by 50%, and Professor Zhao Qingxiang's article does more work, that is, the subject concentration that only causes the microbial respiration rate to decrease by 5%.

Third, a simple discussion of experimental objects.

The activated sludge of three different sewage plants was selected to do the above experiments, Plant A is a pure domestic sewage plant, and the catchment area is pure domestic sewage; Plant B is also a domestic sewage plant, but from time to time some oil substances enter; Plant C is also a domestic sewage plant, but adjacent to the industrial zone, from time to time it is affected by illegal discharge. The above plants selected copper, aluminum, cadmium, chromium, lead, mercury, zinc, arsenic, and nickel as experimental inhibitors.

Fourth, the experimental results (units are mg/L)

Plant A: Copper: 2.4 Aluminum: 18.4 Cadmium: 0.65 Chromium: 1.8 Lead: 50.0 Mercury: 0.05 Zinc: 26.0 Arsenic: 4.3 Nickel: 2.1

Plant B: Copper: 4.3 Aluminum: 15.3 Cadmium: 0.67 Chromium: 2.94 Lead: 20.3 Mercury: 0.03 Zinc: 24.5 Arsenic: 1.8 Nickel: 1.3

Plant C: Copper: 6.7 Aluminum: 10.6 Cadmium: 0.68 Chromium: 2.65 Lead: 73.1 Mercury: 0.04 Zinc: 20.1 Arsenic: 3.2 Nickel: 2.2

The above results can be seen that the EC50 values obtained by different sewage plants in different sink areas and their activated sludge should be different inhibitors are not exactly the same, but some elements such as mercury, zinc, nickel, chromium, etc. are the same or similar, some elements are far apart, more representative is lead element, the three are very different, may be related to the water intake elements in the catchment area, and the data measured by Zhao Qingxiang's paper is like comparison, far lower than the EC50 value measured by it, which may explain that different regions, The properties of different inlet sewage have great differences in the anti-inhibition substances of activated sludge.

4. Excerpts

Professor Zhao made a discussion on the toxic mechanism of different inhibitors, and now briefly excerpts are as follows:

Regarding the mechanism of inhibition of the activity of metal ions on biological sludge, it is not yet completely certain for each metal, but in general, it can be summarized as the following three effects: enzyme is a protein, metal ions are easy to bind to the lucid, amino and shuttle groups in proteins, R one S H + Me + # R one S one Me + H + so that the enzyme is inactive: metal salts are also a precipitant of proteins for enzymes, which can cause denaturation; Metal ions form hydroxides under certain pH conditions, coagulate and precipitate enzymes, and various metal ions hinder the activity of biological sludge, and it is possible that three effects exist at the same time, but the degree of influence is not the same.

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