Anaerobic biological wastewater treatment system and process

A wastewater treatment system for treating wastewater containing organic contaminants, comprising:

• an anaerobic sludge bed reactor, which includes a reactor body, and a first inlet and a first outlet installed on the reactor body, wherein the tank body is suitable for accommodating an anaerobic sludge bed and receiving wastewater containing organic contaminants entering from the first inlet, wherein after being retaining in the tank body for a period of time, the wastewater is discharged from the first outlet, wherein at least a portion of the organic contaminants in the wastewater is decomposed by anaerobic microorganisms in the anaerobic sludge bed during the period of time;
• and
• a dissolved-air flotation (DAF) tank comprising a tank body, a second inlet and a second outlet installed on the tank body, a mixing device, and an air flotation sludge removal device, wherein the second inlet is connected to the first outlet, and wherein the mixing device is used to mix a high pressure air with water discharged from the first outlet and release the mixed high pressure fluid into the DAF tank, wherein the air flotation sludge removal device is used to remove air flotation sludge in the DAF tank from the DAF tank, and wherein the second outlet is used to discharge processed water from the DAF tank.