MBR process for sewage treatment

Process flow

Raw water → grille → regulating tank → lifting pump → Bioreactor → circulating pump → membrane assembly → disinfection device → reclaimed water storage tank → reclaimed water system

MBR sewage treatment process description

After the sewage enters the regulating tank through the grid, it enters the bioreactor through the lifting pump, and starts the aerator through the PLC controller to oxygenate. The effluent from the bioreactor enters the membrane separation and treatment unit through the circulating pump, and the concentrated water returns to the regulating tank. After the membrane separation water is chlorinated and disinfected by rapid mixing method (sodium hypochlorite, bleaching powder, chlorine tablets), it enters the intermediate water storage tank. The backwash pump uses the treated water in the cleaning tank to backwash the membrane treatment equipment, and the backwash sewage returns to the regulating tank. The opening and closing of the lift pump are controlled by the water level in the bioreactor. Filter operation and backwash operation of the membrane unit can be controlled automatically or manually. When the membrane unit needs chemical cleaning operation, close the inlet valve and sewage circulation valve, open the drug washing valve and drug circulation valve, start the drug liquid circulation pump, and carry out chemical cleaning operation.

MBR process characteristics

The application of membrane biological treatment technology in wastewater recycling has the following characteristics:

(1) It can efficiently separate solid and liquid, separating suspended substances, colloidal substances and microbial flora lost by biological units in wastewater from purified water. The separation process is simple, the footprint is small, the effluent water quality is good, and generally it can be reused without three levels of treatment.

(2) The biomass in the biological treatment unit can be maintained at a high concentration, so that the volume load is greatly increased, while the efficiency of membrane separation, the hydraulic residence time of the treatment unit is greatly shortened, and the footprint of the bioreactor is correspondingly reduced.

(3) Because it can prevent the loss of various microbial flora, it is conducive to the growth of bacteria with slow growth rate (nitrifying bacteria, etc.), so that various metabolic processes in the system can proceed smoothly.

(4) Make the residence time of some macromolecules difficult to degrade organic matter longer, which is conducive to their decomposition.

(5) Membrane treatment technology Like other filtration separation technology, in the long-term operation process, the membrane as a filter medium plugging, the membrane through the water running time and gradually decline effective backwashing and chemical cleaning can slow the decline in membrane flux, maintain the effective service life of the MBR system.

(6) MBR technology is applied in urban sewage treatment, because of its simple process and convenient operation, automatic operation management can be achieved.

SBR process

outline

SBR wastewater treatment Process is the Sequencing Batch Reactor Activated Sludge Process, the full name is: sequencing batch reactor activated sludge process.

Referred to as (SBR-Sequencing Batch Reactor) batch activated sludge treatment process, SBR process.

It is a process of wastewater biological treatment of activated sludge based on the degradation of organic matter, ammonia nitrogen and other pollutants in sewage by suspended microorganisms under aerobic conditions. It is a sewage treatment technology that is widely recognized and adopted around the world and runs in intermittent aeration mode in time sequence to change the activated sludge growth environment.

Process flow

A typical SBR process flow is: the wastewater pretreatment through the grid enters the collection well, is lifted by the submersible sewage pump into the SBR reaction tank, and is oxygenated by the water aerator. The treated water is discharged by the drain pipe, and the remaining sludge is discharged into the sludge well after static pressure. The sludge is used as fertilizer.

Batch operation: the operation mode of time division replaces the operation mode of space division. For example, the SBR operation cycle consists of water intake time, reaction time, precipitation time, water decanting time, mud discharge time and idle time, which can be adjusted flexibly.

Calculation method:

Precipitation drainage time (Ts+D) is generally designed according to 2 ~ 4h. Idle time (Tx) is generally designed from 0.5 to 1h. Set the reaction time to (Tf). The time required for a cycle T≥Tf+Ts+D+Tx. [1]

Example of time allocation: the operation cycle is 12h, in which water intake 2h, aeration 4-8h, precipitation 2h, and drainage 1h.

Process characteristics

As an activated sludge process, the SBR process also has advantages and disadvantages of the activated sludge process, such as the advantages of the activated sludge process: strong sewage adaptability and low construction costs.

The disadvantages of activated sludge process: poor operation stability, easy to occur sludge swelling and sludge loss, separation effect is not ideal.