Data of formaldehyde ecology
1. Residue and accumulation: according to the data, the content of formaldehyde adsorbed in the soil of industrial enterprise area can reach 180-720mg / kg dry soil. Soil pollution can lead to groundwater pollution, and the formaldehyde content in water can be 10-20 times higher than that in topsoil.
Formaldehyde is quite stable in the environment. When the concentration of formaldehyde in water is 5mg / L (20 ℃), the observation results show that it can be kept constant within 5 days. When the formaldehyde concentration in the water is less than 20mg / L, it can be degraded and digested by the domesticated microorganism in the aeration tank. When the content is 100mg / L, it can inhibit the oxidation of organic matter by microorganisms. When the formaldehyde content in the water is 500mg / L, the process of biological oxygen consumption stops completely, and the microorganisms in the water are killed.
2. Metabolism and degradation: the main pollution sources of formaldehyde in the environment are waste water and waste gas from industries such as organic synthesis, chemical industry, synthetic fiber, dye, wood processing and paint making. The degradation of some organic compounds in the environment also produces formaldehyde. For example, the degradation products of vinyl chloride also contain formaldehyde. Because formaldehyde has strong reducibility, it can be oxidized to formic acid in the presence of oxidizing substances. For example, formaldehyde entering water environment can be oxidized and decomposed by saprophytic bacteria, so it can consume dissolved oxygen in water. The further decomposition products of formic acid are carbon dioxide and water. Formaldehyde entering the environment is gradually diluted, oxidized and degraded under the joint action of physics, chemistry and biology. The oxidative degradation process of formaldehyde is as follows:
3. Migration and Transformation: formaldehyde is mainly discharged into the environment through the atmosphere and water due to its low boiling point and easy solubility in water. When the emission height of the untreated gas in the factory producing formaldehyde is 18 meters, the formaldehyde content in the air sample 250-500 meters away from the factory is more than 0.035mg/m3. Formaldehyde concentration in the atmosphere is below the olfactory threshold. The concentration of formaldehyde in the air around the enterprises that use formaldehyde as tanning agent to produce plastics is below the olfactory threshold. The concentration of formaldehyde in the air around the enterprises that use formaldehyde as tanning agent to produce plastics is 0.012mg/m3 within 100m from the plant area; 15 of the 36 samples at 200m are less than 0.012mg/m3; and the concentration at 400m is less than 0.012mg/m3.
The formaldehyde content of industrial wastewater varies greatly due to different industries, among which the highest concentration of formaldehyde wastewater is the upper tar wastewater producing phenolic resin, with the formaldehyde content up to 2.5%.