What are the treatment methods of urban domestic sewage?

The water quality characteristics of urban domestic sewage are mainly as follows:

 

》Wastewater contains a large amount of oil, food residue, etc., with high suspended solids and high chroma;

 

》The waste water contains a lot of residual food, etc., which leads to the smell of the waste water, which is easy to stink;

 

》The water quality and quantity of wastewater fluctuate greatly;

 

》The concentration of organic matter in the wastewater is relatively high, and the nitrogen and phosphorus sources are also relatively high. Direct discharge can easily lead to eutrophication of the water body.

 

1. Physical method:

 

It is a relatively simple processing method, and its principle and operation are relatively simple. In the process of project operation, it is generally placed at the front end of the processing method, and it is a commonly used preprocessing method.

 

Industrial wastewater contains scum and floating objects, and living substances contain residues that are not easily dissolved in wastewater. Physical methods can remove some of the above substances, reducing a lot of burden on subsequent treatment.

 

The widely used physical technologies mainly include coagulation and sedimentation technology, etc. For different raw water quality, different pretreatment technologies are used.

 

2. Biological method:

 

It is a treatment method that relies on the microorganisms of activated sludge to ingest and decompose, and uses the organic pollutants of wastewater as "nutrients" to degrade the pollutants themselves, so that the water quality is purified.

 

There are two main types of biological methods, one is anaerobic method and the other is aerobic method.

 

They contain many treatment processes, such as hydrolysis acid process, biological contact oxygen process, UASB process, etc.

 

3. Chemical method:

 

Oxidative decomposition, flocculation and precipitation of chemicals and pollutants in wastewater are used to reduce the pollutant index of wastewater.

 

The chemical method has extremely high flexibility. It can adjust the dosing amount with the change of concentration without affecting the overall process, and more vigorously ensure the discharge of wastewater up to the standard. It plays a key role in cost control and emergency treatment.