chemical wastewater treatment project

1. Project overview

According to the relevant information provided by the owner, the wastewater treated by the sewage station of this project mainly includes esterification wastewater and polymerization wastewater, among which esterification wastewater is 43.2m3/d and polymerization wastewater is 4.8m3/d. The wastewater has a high concentration and contains some polymeric lipid pollutants. The daily discharge of sewage is expected to reach 198m3/d, and the treated sewage is discharged to the local sewage treatment plant for further treatment.

2. Design inlet and outlet water quality

Design inlet water quality is as follows:

COD: 20000mg/L

SS: 160mg/L

pH: 3~5

Ammonia nitrogen: 128mg/L

Formaldehyde: 87mg/L

Phenol: 1896mg/L

The effluent index is as follows:

COD: 500mg/L

SS: 250mg/L

pH: 6 ~ 9

Chroma: 100mg/L

Petroleum: 20mg/L

Volatile phenol: 2mg/L

Ammonia nitrogen: 25mg/L

Formaldehyde: 5mg/L

TDS: 3000mg/L

3. Technical analysis of wastewater treatment process

In the project, the production wastewater treated by the sewage station mainly consists of esterification wastewater and polymerization wastewater, both of which contain certain grease, and need to be separately collected after oil removal and quantitatively mixed with other wastewater for treatment.

The amount of polymeric wastewater is small, but the COD concentration is as high as 197000mg/L, and it is especially necessary to control the amount of this wastewater when mixing. The amount of water in the esterification wastewater is large, the COD concentration is about 30,000-5000mg /L, the main pollutants are from ethylene glycol, aldehydes, terephthalic acid and their intermediate products, and the composition of the wastewater is complex. The molecular weight of the main pollutants in wastewater is low, which is suitable for treatment by microbial metabolism, but the direct biochemical treatment of wastewater has a certain toxic effect on microorganisms. Therefore, for high-concentration chemical wastewater, appropriate physical and chemical pretreatment should be carried out before further biochemical treatment. Dilute water is mixed with the first two streams of high concentration water to reduce the biological toxicity of wastewater.

The project adopts physicochemical pretreatment to remove toxic substances in wastewater, improve the biodegradability of wastewater, and reduce the difficulty of biochemical treatment of wastewater. Then, it is mixed with other wastewater for biochemical treatment and advanced treatment.