The most complete sewage treatment process introduction

Basic methods of sewage treatment

According to the nature of the treatment method

1. Physical method: precipitation, filtration, oil separation, air flotation, centrifugal separation, magnetic separation

2. Chemical method: coagulation precipitation method, neutralization method, REDOX method, chemical precipitation method

3. Physical and chemical method: adsorption method, ion exchange method, extraction method, blowing, stripping

4. Biological method: activated sludge method, biofilm method, anaerobic process, biological nitrogen and phosphorus removal process

According to the water quality and the destination of the treated water

Primary treatment: Mechanical treatment (pretreatment stage)

Coarse grille and fine grille, sand settling pool, initial settling pool, air floating pool, regulating pool

Secondary treatment: the main process is biochemical treatment (main)

Activated sludge process, CASS process, A2/O process, A/O process, SBR, oxidation ditch, hydrolysis acidification pool.

Tertiary treatment: control of eutrophication and reuse

Advanced catalytic oxidation, biological aeration filter, fiber filter, active sand filtration, reverse osmosis, membrane treatment

Water reuse generally has a disinfection pool: ultraviolet ozone disinfection pool, chlorine dioxide disinfection pool

Primary treatment of sewage

Primary treatment: Mechanical treatment (pretreatment stage)

Regulating tank, coarse grid and fine grid, sand settling tank, initial settling tank, air floating tank, hydrolysis acidification tank

Regulating tank

Regulating the function of the pool

1. In order to ensure the normal operation of subsequent treatment structures or equipment, the amount and quality of sewage should be adjusted.

2. Acidic sewage and alkaline sewage are mixed in the regulating tank to achieve the purpose of neutralization.

3. Short-term discharge of high temperature sewage can also be adjusted to balance the water temperature.

grille；

It is a metal frame made of a set of parallel metal bars, positioned diagrammed over the channel through which the waste water flows or at the inlet of the sump of a pumping station, to intercept large blocks of suspended or floating solid pollutants, so as not to clog the drainage pipes of the pumps and settling tanks. The trapping effect depends on the gap width and the nature of the water.

Divided by specifications:

Coarse grid (50~100mm), medium grid (10~40mm), fine grid (3~10mm)

Grit basin

1. Function: Separating dense inorganic particles from sewage, protecting pumps and pipes from wear, reducing the volume of sludge treatment structures, improving the content of organic components of sludge, and improving the value of sludge as fertilizer.

2. Sand sedimentation tank type: aerated sand sedimentation tank, flat flow sand sedimentation tank

Aerated sand sedimentation tank:

Aerated sand sedimentation tank is a rectangular pool in one side of the air, so that the sewage swirl movement, the flow rate from the periphery to the center gradually reduced, sand particles in the bottom of the sand collection tank and water separation, organic matter in the sewage and washed down from the sand sludge is still in a suspended state, with the water flow into the treatment structure behind.

In fact, the flat-flow sedimentation tank is a channel wider and deeper than the flow channel and the outflow channel. When the sewage flows through, due to the increase of the cross section, the flow speed decreases, and the inorganic particles in the wastewater sink under the action of gravity, so as to achieve the purpose of separating the inorganic particles in the water.

Advantages and disadvantages of flat flow sedimentation tank and aerated sedimentation tank:

The biggest disadvantage of ordinary sand sedimentation tank is that there are some organic substances in the trapped sand. The existence of these organic substances makes the sand easily corrupt and smelly, especially when the temperature is high in summer, which has an adverse effect on the treatment of sand sedimentation and the surrounding environment. Another disadvantage of ordinary sand settling tank is the poor retention effect of sand wrapped in organic matter.

The advantage of aerated sand settling tank is that the sand removal efficiency is stable and less affected by the change of influent flow rate. The hydraulic rotation makes the separation effect of sand and organic matter better. In the sand discharged from the aerated sedimentation tank, organic matter only accounts for about 5%, and it will not rot and stink for a long time. At the same time, the process of sand sedimentation by aeration can also play the role of oil floating and blowing off volatile organic compounds and pre-aeration oxygenation and oxidation of some organic compounds.

Settling basin

1. Working principle of sedimentation tank: Water purification can be achieved by using the principle that the downward sedimentation rate of the suspended impurity particles in the water flow is greater than the downward flow rate of the water flow, or the downward sedimentation time is less than the time of the water flow out of the sedimentation tank.