WO2019153584A1

WO2019153584A1 - Sewage advanced-treatment apparatus and method

Info

Publication number: WO2019153584A1
Application number: PCT/CN2018/088770
Authority: WO
Inventors: 陶益; 周灿炜; 陈光耀
Original assignee: 清华大学深圳研究生院
Priority date: 2018-02-09
Filing date: 2018-05-29
Publication date: 2019-08-15
Also published as: CN108217964A; CN108217964B

Abstract

A sewage advanced-treatment method, which uses Monoraphidium contortum to implement nitrogen and phosphorus removal under a predetermined light condition. The method comprises the following steps: 1) sewage enters a reaction pool (2) by means of a water inlet, a first aeration means (14) supplies gas to the reaction pool (2), and the sewage and microalgae mixture obtained after treatment in the reaction pool (2) enter a membrane pool (3); 2) a second aeration means (9) supplies gas to the membrane pool (3), a membrane filter component (4) in the membrane pool (3) separates the microalgae from water, the treated water is exhausted by means of a water exhaust port on the membrane filter component (4), a part of the microalgae and sewage mixture in the membrane pool (3) returns to the reaction pool (2), and a part of the mixture is exhausted by means of a microalgae exhaust port. Also disclosed is a sewage advanced-treatment apparatus, comprising a reaction pool (2), a membrane pool (3), a first aeration means (14), and a second aeration means (9).

Description

Wastewater advanced treatment device and method

Technical field

The invention relates to the field of sewage treatment and water pollution control, in particular to a sewage treatment device and method.

Background technique

Nitrogen, phosphorus and other elements are important pollutants that cause eutrophication of water bodies. Controlling the emission of nitrogen and phosphorus is an important means to control the eutrophication of natural water bodies. The existing sewage treatment process can remove most of the nitrogen and phosphorus in the water body, but a large number of studies have shown that the nitrogen and phosphorus contained in the sewage still cause a higher risk of eutrophication of the receiving water body after the existing sewage treatment process. At present, biological treatment means can effectively remove nitrogen and phosphorus in the secondary sedimentation water, but has the problems of large floor area and long hydraulic retention time. The chemical treatment means can effectively remove the residual phosphorus in the sewage, but has no removal effect on the nitrogen element, and also produces excess sludge which is difficult to handle.

In recent years, microalgae has been increasingly used in the treatment of raw sewage water. There are also attempts to apply microalgae to the treatment of secondary effluent from sewage plants. However, due to the low trophic characteristics of secondary effluent from wastewater treatment plants, micro Algae are often difficult to grow or grow at a slow rate, resulting in long hydraulic retention times and the difficulty of achieving efficient nitrogen and phosphorus removal.

Summary of the invention

In order to remedy the above deficiencies of the prior art, the present invention proposes a sewage treatment system and method that are both efficient and energy efficient.

In order to remedy the above-mentioned deficiencies of the prior art, the present invention provides an advanced sewage treatment apparatus and method which can remove nitrogen and phosphorus in an extremely efficient and thorough manner.

The invention adopts the following technical solutions:

An advanced sewage treatment device comprises a reaction tank, a membrane tank, a first aeration device and a second aeration device; the reaction tank is provided with a water inlet and a microalgae return inlet, the outlet of the reaction tank and the membrane The inlet of the pool is connected; the membrane pool is provided with an algae outlet and a microalgae reflux outlet, and the algae reflux outlet on the membrane pool is connected to the microalgae reflux inlet on the reaction tank through a reflux pump and a reflux tube, wherein the membrane pool is Membrane filter assembly is provided, the membrane filter assembly is provided with a drain port through which water is filtered; the first aeration device is disposed under the reaction tank for supplying gas into the reaction tank The second aeration device is disposed below the membrane tank for supplying gas into the membrane tank.

Preferably, the volume ratio of the membrane pool to the reaction cell is 1:1 to 1:4.

Preferably, further comprising a gas mixer, the inlet of the gas mixer is respectively connected with the air delivery tube and the carbon dioxide delivery tube, and the outlet of the gas mixer is respectively passed through the pipeline and the first aeration device and The second aeration device is connected.

Preferably, a microalgae collection tank is further included, and the algae drain on the membrane pool is in communication with the microalgae collection tank.

An advanced sewage treatment method, wherein the method is performed under predetermined lighting conditions by using the sewage advanced treatment device, wherein the reaction tank and the membrane pool of the sewage advanced treatment device contain microalgae, and the microalgae is rotated Single needle algae; includes the following steps:

(1) the sewage enters the reaction tank through the water inlet, the first aeration device supplies gas into the reaction tank, and the sewage and the microalgae mixture liquid treated by the reaction tank enters the membrane pool;

(2) The second aeration device supplies gas into the membrane tank, and the membrane filtration module in the membrane tank separates the microalgae from the water, and the treated water is discharged through the drainage port on the membrane filtration module, and the microalgae and sewage in the membrane pool A part of the mixed liquid was refluxed into the reaction tank, and a part was discharged through the algae discharge port.

Preferably, the first aeration device supplies a gas into the reaction tank, and the second aeration device supplies a gas into the membrane pool: providing a mixed gas of air and carbon dioxide, in the mixed gas, The volumetric concentration of carbon dioxide is 1% to 2%; the aeration rate is 0.2v/v·min ^-1 to 0.4v/v·min ^-1 .

Preferably, in the step (2), the reflux ratio of the microalgae and the sewage mixture is 50% to 200%.

Preferably, the sewage deep treatment device has a hydraulic retention time (HRT) of 2 h to 6 h; and the microalgae residence time (SRT) is 1 day to 4 days.

Preferably, the predetermined illumination condition is: light intensity is 350-1000 μmol·m ^-2 ·s ^-1 , light-dark cycle ratio is 12h: 12h - 24h: 0h; illumination is provided by sunlight and/or cold fluorescent light source .

Preferably, in the step (1), the sewage entering the reaction tank through the water inlet: the total nitrogen concentration is 2-15 mg/L, the total phosphorus concentration is 0.2-1.5 mg/L, and the chemical oxygen demand is <60 mg/L.

Advantageous effects of the present invention in comparison with the prior art include that the method of the present invention has the characteristics of high processing efficiency and short residence time. After the sewage is treated by the invention, the total inorganic nitrogen of the effluent can be reduced below the detection limit of the national standard ultraviolet spectrophotometry (<0.02 mg/L), and the total phosphorus of the effluent can be reduced to the national standard molybdenum anti-spectrophotometric detection limit. (<0.02mg/L), it can achieve the removal rate of >99% within 6h of HRT, and the average removal effect can reach 99% in long-term operation. By applying this application, the nitrogen and phosphorus content of the effluent from the sewage treatment plant is controlled to a very low level. It is of great significance to reduce the nutrient load of the receiving water body and alleviate the risk of eutrophication of water bodies.

DRAWINGS

1 is a schematic view of an advanced sewage treatment device in an embodiment of the present invention.

Detailed ways

The invention will now be further described with reference to the drawings in conjunction with the preferred embodiments. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

An advanced sewage treatment device is provided, which comprises a reaction tank, a membrane tank, a first aeration device and a second aeration device; wherein the reaction tank is provided with a water inlet and a microalgae return inlet, and the outlet of the reaction tank and the membrane pool The inlet is connected; the membrane pond is provided with an algae outlet and a microalgae reflux outlet, and the algae reflux outlet on the membrane tank and the microalgae reflux inlet on the reaction tank are connected through a reflux pump and a reflux tube, and a membrane filtration module is arranged in the membrane tank, and the membrane filtration module is arranged A drain port is provided, and the water is filtered through the membrane filter unit; the first aeration device is disposed under the reaction tank for supplying gas into the reaction tank; and the second aeration device is disposed below the membrane tank for supplying gas into the membrane pool.

In a preferred embodiment, the volume ratio of the membrane cell to the reaction cell is from 1:1 to 1:4.

In a preferred embodiment, the sewage advanced treatment device further includes a gas mixer, the inlet of the gas mixer is respectively connected with the air delivery tube and the carbon dioxide delivery tube, and the outlet of the gas mixer is respectively passed through the pipeline and the The first aeration device is connected to the second aeration device, and by such an arrangement, a mixed gas of air and carbon dioxide can be supplied into the reaction cell and the membrane pool, wherein the volume concentration of carbon dioxide in the mixed gas is 1% to 2%; The aeration rate is 0.2v/v·min ^-1 to 0.4v/v·min ^-1 .

In a preferred embodiment, the sewage advanced treatment device further comprises a microalgae collection tank, and the algae drain on the membrane pool is connected with the microalgae collection tank, so that the microalgae can be discharged first (for example, by means of overflow) In the algae collection pond, the microalgae in the microalgae collection pond can be transported to other places.

Wherein, a fully mixed aerated photobioreactor can be divided into two zones, one zone as a reaction cell and one zone as a membrane cell; or two fully aerated photobioreactors (one as a reaction) The pool, one as a membrane tank) is assembled into a sewage treatment unit. The membrane filtration module may be, for example, a microfiltration membrane or an ultrafiltration membrane having a pore diameter of 0.01 to 1 μm.

There is also provided an advanced treatment method for sewage, which is carried out under predetermined lighting conditions by using the sewage advanced treatment device, and the micro-algae is contained in the reaction tank and the membrane pool of the sewage advanced treatment device, and the microalgae is rotated. Monochaphide (Monoraphidium.sp.); includes the following steps:

(1) The sewage enters the reaction tank through the water inlet, and the first aeration device supplies gas into the reaction tank, and the sewage and the microalgae mixture that has passed through the reaction tank enters (for example, can overflow to the membrane by overflow) Pool

In a preferred embodiment, the first aeration device supplies gas into the reaction tank, and the second aeration device supplies gas into the membrane tank: providing a mixed gas of air and carbon dioxide, In the mixed gas, the volume concentration of carbon dioxide is 1% to 2%; and the aeration rate is 0.2 v/v·min ^-1 to 0.4 v/v·min ^-1 . The aeration device may be, for example, a microporous aeration strip. The microbubbles generated by the gas can play a role of mixing and stirring the liquid in the reaction tank, and scouring the membrane filtration component in the membrane pool to control membrane fouling, and at the same time, the gas in the reaction tank and the membrane pool can be micro. The algae replenish the carbon source and always maintain a pH between 6.5 and 7.5 in the membrane cell and in the reaction cell.

In a preferred embodiment, when the sewage is treated in depth, the reaction tank is in the form of a full mixed reaction, the influent form is continuous influent, the effluent form is continuous effluent, and the algae in the membrane pond is continuous algae, which can be regulated by the feed water pump. The flow rate of the influent water entering the reaction tank is regulated by the outlet pump to regulate the flow rate of the effluent from the membrane tank, and the flow rate of the microalgae and the sewage mixture flowing back from the membrane tank to the reaction tank is regulated by the reflux pump, so that in the step (2), The reflux ratio of the algae and sewage mixture is 50% to 200%; the HRT time for the advanced treatment of sewage is 2h to 6h, and the SRT is 1 to 4 days.

In a preferred embodiment, the predetermined illumination condition is: light intensity is 350-1000 μmol·m ^-2 ·s ^-1 , light-dark cycle ratio is 12h: 12h - 24h: 0h; by sunlight and/or cold A fluorescent light source provides illumination. The light intensity may further preferably be 350 to 700 μmol·m ^-2 ·s ^-1 , and the cold fluorescent light source may be used as a substitute light source when there is no solar light source, or as a supplementary light source when the intensity of the solar light source is insufficient. In order to ensure the smooth penetration of the light source, when the illumination mode is side illumination, the main material of the reaction cell and the membrane pool may be plexiglass; when the illumination mode is the upper illumination, the main material of the reaction cell and the membrane pool may be stainless steel. Such as opaque material; when using a cold fluorescent light source, the fluorescent tube can be evenly distributed on the light side to provide the light required for growth of the microalgae inside the reaction cell and the membrane pool.

In a preferred embodiment, in the step (1), the sewage entering the reaction tank through the water inlet: the total nitrogen concentration is 2-15 mg/L, the total phosphorus concentration is 0.2-1.5 mg/L, and the chemical oxygen demand concentration is < 60mg/L, for example, the sewage to be treated may be secondary effluent from domestic sewage plant or other low nutrient sewage.

In the present invention, the inventors have found that even in a sewage having low nutrition (total nitrogen concentration of 2 to 15 mg/L, total phosphorus concentration of 0.2 to 1.5 mg/L, and chemical oxygen demand of <60 mg/L), The used Spirulina platensis can also efficiently and thoroughly remove nitrogen and phosphorus in the corresponding conditions of the above device of the present application, and has strong anti-interference, high light intensity tolerance, high pollutant absorption, and extremely low nitrogen and phosphorus. The characteristics of the concentration tolerance, the operation process can be, using the secondary sewage from the domestic sewage plant or other low-nutrient sewage to culture the microalgae, inoculate the algae into the above reaction tank and membrane pool, and give continuous water in a certain Under the aeration and illumination conditions of carbon dioxide concentration, the nitrogen and phosphorus are absorbed by the microalgae, thereby reducing the concentration of nitrogen and phosphorus in the influent water, and separating the microalgae and water through the membrane filtration module, and then continuously discharging water.

In the example shown in FIG. 1, the sewage advanced treatment device includes a feed water pump 1, a reaction tank 2, a membrane tank 3, a membrane filtration module 4, an outlet pump 5, an air pump 6, a carbon dioxide delivery tube 7, and a gas mixer. 8. First aeration device 14 (microporous aeration strip), second aeration device 9 (microporous aeration strip), reflux pump 10, algae valve 11, microalgae collection tank 12, and light source 13 (sunlight) Or cold fluorescence). Among them, the arrows in the figure indicate the flow direction of water, microalgae and sewage mixture (hereinafter also referred to as algae liquid) or gas, and the sewage enters the reaction tank 2 through the feed water pump 1 and the water inlet, and the microalgae treated by the reaction tank 2 The mixture with water overflows into the membrane tank 3, and the membrane filtration module 4 in the membrane tank 3 is connected to the water pump 5, which separates the microalgae from the water, and the treated water passes through the drain port on the membrane filtration module 4 The outlet pump 5 is discharged to obtain the treated sewage, and a part of the microalgae and the sewage mixture in the membrane tank 3 is returned to the reaction tank 2 through the reflux pump 10, and a part is discharged to the microalgae collection tank through the algae discharge port and the algae valve 11. 12. The microalgae in the microalgae collection tank 12 is further discharged for subsequent treatment; the air enters the gas mixer 8 through the air pump, is mixed with the carbon dioxide entering the gas mixer 8 through the carbon dioxide delivery tube, and then transported to the respective The first aeration device 14 and the second aeration device 9 supply air to the reaction cell and the membrane cell.

This application is further described below by way of a more specific embodiment.

Example 1

Manually prepared medium to simulate low nutrient wastewater (TN 13 ~ 15mg / L, TP 1.3 ~ 1.5mg / L, chemical oxygen demand <60mg / L, non-nitrogen phosphorus components and BG11 medium), in the reaction tank and Rotating single-needle algae inoculated in the membrane pool, the initial inoculation density is about 1×10 ⁷ /mL, the simulated low-nutrient sewage enters the reaction tank 2 from the feed water pump 1, regulates the flow of the air pump 6, and controls the microporous aeration strip aeration. The carbon dioxide concentration is 1-2%, the aeration rate is 0.2-0.3 (v/v·min ^-1 ), the illumination intensity of the cold fluorescent lamp is adjusted to 400 μmol·m ^-2 ·s ^-1 , and the light-dark cycle ratio is set to 24h/0h. The HRT of the reaction tank is set to 2 to 4 hours, the algae liquid in the reaction tank overflows to the membrane tank 3, the water flow rate is controlled by the water discharge pump 5 connected to the membrane filtration module 4, and the membrane filtration is monitored by a pressure gauge (not shown) on the water outlet pipe. The components are cleaned regularly. The HRT of the membrane pool is set to 1 to 2 h, and part of the algae liquid is refluxed to the reaction tank 2 by a reflux pump 10 at a reflux ratio of 50% to 100%, and the algae liquid in the membrane pool 3 overflows to the microalgae collection tank 12, and then passes through the row. The algae pump (not shown) is discharged.

In this example, due to the low residence time setting, under the conditions of low influent nitrogen and phosphorus nutrition, the nitrogen and phosphorus nutrient load of the advanced sewage treatment device can still reach 60-95g N/(m ³ ·d) and 6-9.5g P respectively. /(m ³ ·d). Rotating single-needle algae can achieve almost complete nitrogen and phosphorus absorption, nitrogen and phosphorus removal rates are above 99%, and effluent nitrogen and phosphorus concentrations are lower than UV spectrophotometry and molybdenum anti-spectrophotometric detection limits (<0.02mg/ L). The concentration of microalgae in the reaction cell and the membrane cell in the apparatus can reach 0.75 to 1.2 kg/m ³ and 1.5 to 2.2 kg/m ³ (dry weight), respectively. The yield of microalgae can reach 1~1.6kg/(m ³ ·d).

Example 2

Take the actual secondary effluent of a domestic sewage treatment plant (TN 6～12mg/L, TP 0.3～1.0mg/L, chemical oxygen demand <60mg/L), inoculate Rotary single-needle algae in the reaction tank and membrane tank, initial seeding density About 5×10 ⁶ /mL, the secondary effluent enters the reaction tank 2 by the feed water pump 1, adjusts the flow rate of the air pump 6, controls the aeration of the microporous aeration strip to a concentration of 1-2%, and the aeration rate is 0.2-0.3. (v/v·min ^-1 ), adjust the illumination intensity of cold fluorescent lamp to 350μmol·m ^-2 ·s ^-1 , set the light-dark cycle ratio to 12h/12h, set the HRT of the reaction cell to 3~4h, and the algae in the reaction cell The liquid overflows to the membrane tank 3, and the water flow rate is controlled by the water discharge pump 5 connected to the membrane filtration unit 4, and the membrane filtration module is monitored by a pressure gauge (not shown) on the outlet pipe and periodically cleaned. The HRT of the membrane pool is set to 1.5 to 2 h, and part of the algae liquid is refluxed to the reaction tank 2 by a reflux pump 10 at a reflux ratio of 200%, and the algae liquid in the membrane pool 3 overflows to the microalgae collection tank 12, and then passes through the algae pump ( It is not shown in the figure.

In this example, the nitrogen and phosphorus nutrient load of the sewage advanced treatment device can still reach 30 to 50 g N/(m ³ ·d) and 4 to 6 g P/(m ³ ·d), respectively. Rotating single-needle algae can achieve almost complete nitrogen and phosphorus absorption, nitrogen and phosphorus removal rates are above 99%, and effluent nitrogen and phosphorus concentrations are lower than UV spectrophotometry and molybdenum anti-spectrophotometric detection limits (<0.02mg/ L). The concentration of microalgae in the reaction cell and the membrane cell in the apparatus may be 0.4 to 0.6 kg/m ³ and 0.7 to 1.0 kg/m ³ (dry weight), respectively. The yield of microalgae can reach 0.5-0.8 kg/(m ³ ·d).

The invention utilizes the advanced treatment device and method for the high-efficiency limit nitrogen and phosphorus removal of rotating single-needle microalgae, and applies the rotating single-needle algae as the high-efficiency limit nitrogen and phosphorus removal microalgae, and adopts the sewage plant secondary sedimentation water or similar low nitrogen phosphorus group. Separation of sewage, under the residence time of 6h, the growth rate of microalgae up to 1.6kg / (m ³ · d) and nitrogen of 95g N / (m ³ · d), 9.5g P / (m ³ · d) Phosphorus removal efficiency, after treatment by the device and method, the nitrogen and phosphorus removal rate in the sewage can reach more than 99%.

The above is a further detailed description of the present invention in connection with the specific preferred embodiments, and the specific embodiments of the present invention are not limited to the description. It will be apparent to those skilled in the art that <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt;

Claims

An advanced sewage treatment device, comprising: a reaction tank, a membrane tank, a first aeration device and a second aeration device;

The reaction tank is provided with a water inlet and a microalgae return inlet, and the outlet of the reaction tank is connected to the inlet of the membrane pool;

The membrane pool is provided with an algae outlet and a microalgae reflux outlet, and the algae reflux outlet on the membrane pool is connected with the microalgae reflux inlet on the reaction tank through a reflux pump and a reflux tube, and the membrane tank is provided with a membrane filter assembly The membrane filter assembly is provided with a drain port through which the water is filtered;

The first aeration device is disposed under the reaction tank for supplying gas into the reaction tank; the second aeration device is disposed below the membrane pool for supplying gas into the membrane pool.
The sewage treatment apparatus according to claim 1, wherein the volume ratio of the membrane pool to the reaction tank is 1:1 to 1:4.
The sewage deep processing apparatus according to claim 1, further comprising a gas mixer, wherein the inlet of the gas mixer is respectively connected to the air delivery pipe and the carbon dioxide delivery pipe, and the gas mixer is connected to the outlet. The first aeration device and the second aeration device are respectively connected through a pipeline.
The sewage treatment apparatus according to claim 1, further comprising a microalgae collection tank, wherein the algae drain on the membrane pool is in communication with the microalgae collection tank.
An advanced treatment method for sewage, characterized in that the method is carried out under predetermined illumination conditions by using the sewage advanced treatment device according to claim 1, wherein the reaction tank and the membrane pool of the sewage advanced treatment device contain microalgae The microalgae is a rotating single needle algae; comprising the following steps:

(1) the sewage enters the reaction tank through the water inlet, the first aeration device supplies gas into the reaction tank, and the sewage and the microalgae mixture liquid treated by the reaction tank enters the membrane pool;

(2) The second aeration device supplies gas into the membrane tank, and the membrane filtration module in the membrane tank separates the microalgae from the water, and the treated water is discharged through the drainage port on the membrane filtration module, and the microalgae and sewage in the membrane pool A part of the mixed liquid was refluxed into the reaction tank, and a part was discharged through the algae discharge port.
The advanced sewage treatment method according to claim 5, wherein the first aeration device supplies gas into the reaction tank, and the second aeration device supplies gas into the membrane tank: a mixed gas of air and carbon dioxide, wherein the volume concentration of carbon dioxide is 1% to 2%; and the aeration rate is 0.2 v/v·min -1 to 0.4 v/v·min -1 .
The advanced sewage treatment method according to claim 5, wherein in the step (2), the reflux ratio of the microalgae and the sewage mixture is 50% to 200%.
The sewage deep treatment method according to claim 5, wherein the sewage deep treatment device has a hydraulic retention time of 2 h to 6 h; and the microalgae residence time is 1 day to 4 days.
The advanced sewage treatment method according to claim 5, wherein the predetermined illumination condition is: an illumination intensity of 350 to 1000 μmol·m -2 ·s -1 , and a light-dark cycle ratio of 12 h: 12 h to 24 h: 0h; illumination provided by sunlight and/or a cold fluorescent source.
The advanced sewage treatment method according to claim 5, wherein in the step (1), the sewage entering the reaction tank through the water inlet is: the total nitrogen concentration is 2 to 15 mg/L, and the total phosphorus concentration is 0.2 to 1.5 mg. /L, chemical oxygen demand <60mg / L.