METHOD AND SYSTEM OF WASTEWATER TREATMENT USING FACULTATIVE-ORGANISM-ADAPTED MEMBRANE BIOREACTOR

Abstract

A wastewater treatment system including a facultative-organism-adapted membrane bioreactor. The facultative-organism-adapted membrane bioreactor includes a reaction vessel, a membrane separation system, a water production system and an aeration system. The membrane separation system is disposed in the reaction vessel. The water production system communicates with the membrane separation system to pump a filtrate out of the membrane separation system. A wastewater treatment method using the facultative-organism-adapted membrane bioreactor includes: aerating the reaction vessel to enable a dissolved oxygen concentration in over 50% of the reaction vessel is smaller than 1 mg/L, a dissolved oxygen concentration in the membrane separation system is smaller than 2.0 mg/L, and a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system to be greater than 0 and smaller than 1.0 mg/L.

Claims

1. A wastewater treatment system comprising a facultative-organism-adapted membrane bioreactor, the facultative-organism-adapted membrane bioreactor comprising: a reaction vessel; a membrane separation system, the membrane separation system being disposed in the reaction vessel; a water production system; and an aeration system; wherein the water production system communicates with the membrane separation system to pump a filtrate out of the membrane separation system; and the aeration system is employed to aerate the reaction vessel and the membrane separation system.

2. The system of claim 1, wherein by controlling an aeration rate of the aeration system, a dissolved oxygen concentration in over 50% of the reaction vessel is greater than 0 and smaller than 1 mg/L, a dissolved oxygen concentration in the membrane separation system is greater than 0 and smaller than 2.0 mg/L, and a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system is greater than 0 and smaller than 1.0 mg/L; the dissolved oxygen concentration in the membrane separation system is higher than the dissolved oxygen concentration in the reaction vessel excluding the membrane separation system.

3. The system of claim 1, wherein the water production system is a suction type water production system or a gravity flow type water production system.

4. The system of claim 1, the membrane separation system employs a microfiltration membrane or an ultrafiltration membrane.

5. A method of wastewater treatment using a facultative-organism-adapted membrane bioreactor of claim 1, the method comprising: 1) aerating the reaction vessel to enable a dissolved oxygen concentration in over 50% of the reaction vessel to be greater than 0 and smaller than 1.0 mg/L, a dissolved oxygen concentration in the membrane separation system to be greater than 0 and smaller than 2.0 mg/L, and a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system to be greater than 0 and smaller than 1.0 mg/L; and 2) controlling the dissolved oxygen concentration in the membrane separation system to be higher than the dissolved oxygen concentration in the reaction vessel excluding the membrane separation system.

6. A method of upgrading a common membrane bioreactor into a facultative-organism-adapted membrane bioreactor, the common membrane bioreactor comprising a reaction vessel comprising separators and a front reaction zone, the method comprising: a) demolishing the separators or the front reaction zone of the reaction vessel; b) cutting down an aeration rate of a blower or reducing the arrangement of aeration pipes of an aeration system to enable a dissolved oxygen concentration in over 50% of the reaction vessel to be greater than 0 and smaller than 1.0 mg/L, a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system to be greater than 0 and smaller than 2.0 mg/L, and a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system to be greater than 0 and smaller than 1.0 mg/L; and controlling the dissolved oxygen concentration in the membrane separation system to be higher than the dissolved oxygen concentration in the reaction vessel excluding the membrane separation system; and c) demolishing or stopping a sludge discharge system, a sludge return system and sludge treatment equipment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a schematic diagram of a membrane bioreactor (MBR) in the prior art; and

[0018] FIG. 2 is a schematic diagram of a wastewater treatment system comprising a facultative-organism-adapted membrane bioreactor in accordance with one exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] For further illustrating the invention, experiments detailing a method and system of wastewater treatment using a facultative-organism-adapted membrane bioreactor are described below. It should be noted that the following examples are intended to describe and not to limit the invention.

[0020] A wastewater treatment system comprises a facultative-organism-adapted membrane bioreactor. The facultative-organism-adapted membrane bioreactor comprises a reaction vessel 7, a membrane separation system 8, a water production system 9 and an aeration system 10, as shown in FIG. 2. The membrane separation system 8 is disposed in the reaction vessel 7. The membrane separation system 8 employs a microfiltration membrane or an ultrafiltration membrane. The water production system optionally adopts a suction type water production system and a gravity flow type water production system. By controlling an aeration rate of the aeration system 10, a dissolved oxygen concentration in over 50% of the reaction vessel is greater than 0 and smaller than 1.0 mg/L, a dissolved oxygen concentration is greater than 0 and smaller than 2.0 mg/L in the membrane separation system, and a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system to be greater than 0 and smaller than 1.0 mg/L, and the dissolved oxygen concentration in the membrane separation system is higher than the dissolved oxygen concentration in the reaction vessel excluding the membrane separation system, so as to form a dissolved oxygen concentration gradient in the reaction vessel 7 and meanwhile flush the membrane separation system 8 by aeration.

[0021] The invention also provides an example of upgrading a common wastewater treatment system into a wastewater treatment system comprising a facultative-organism-adapted membrane bioreactor.

[0022] A school employed the wastewater treatment system comprising a common membrane bioreactor (MBR), with a treatment capacity of 100 t/d. A schematic diagram of the prior MBR is shown as FIG. 1. The MBR was an integrated device, comprising: a reaction pool 1, a membrane separation system 2, a water production pump 3, an aeration system 4, sludge discharge and return system 5, a sludge pump 6, and sludge treatment equipment. The reaction pool 1 was separated into a diversion zone A, an anoxic zone B, and a membrane reaction zone C. An independent aeration pipe and blower were disposed on each reaction zone. The sludge was discharged from the MBR every three days, for 15 minutes each time. Sludge in the membrane reaction zone C returned to the diversion zone A, with a return ratio of 1:1. The power consumption per unit during operation period was 0.86 kWh/t, and staffs were on duty for 24 hours at the wastewater station.

[0023] Steps to upgrade the MBR (as shown in FIG. 1) into a facultative-organism-adapted membrane bioreactor comprise: [0024] a) demolishing the separators in the reaction vessel; [0025] b) changing the configuration of the aeration system, and employing only one blower to aerate; and [0026] c) demolishing the sludge discharge system, the sludge return system and sludge treatment equipment.

[0027] After the above steps, the original MBR membrane bioreactor was upgraded into a wastewater treatment system comprising a facultative-organism-adapted membrane bioreactor as shown in FIG. 2. The wastewater treatment system comprises a reaction vessel 7, a membrane separation system 8, a water production system 9 and an aeration system 10, and the reaction pool 7 was provided with a facultative membrane reaction zone D. The rated power of the blower decreased from 3.3 kWh to 1.5 kWh, and an organism system is rebuilt. The average concentration of the dissolved oxygen in the reactor was 0.72 mg/L. Zero sludge was discharged, and the power consumption per unit during operation period was 0.39 kWh/t. The wastewater station was unattended, and staffs only needed to patrol once a week.