CN115448495B - Method for improving sewage resource utilization through membrane concentration - Google Patents

Abstract

The invention discloses a method for improving sewage resource utilization through membrane concentration, which comprises the following steps: (1) Mixing the sewage, the adsorbent and the coagulant to form a mixed solution; (2) Introducing the mixed liquor into a membrane concentration device so as to separate clear liquid in the mixed liquor from the sludge mixture; (3) The sludge mixture and the inoculum are mixed for anaerobic digestion reaction. Therefore, more organic matter resources in the sewage are captured, anaerobic digestion capacity of the sludge is improved, methane yield per unit VS is improved by 10.2-31.9% compared with primary sludge, and methane yield per unit VS is improved by 7.8-29.1% compared with residual sludge, so that the problems of high energy consumption, insufficient recycling of resources and the like caused by continuous aeration of the traditional sewage treatment process based on an activated sludge method are solved.

Description

Methods to improve wastewater resource utilization through membrane concentration

Technical field

The invention belongs to the field of environmental protection and renewable energy utilization, and specifically relates to a method for improving the utilization of sewage resources through membrane concentration.

Background technique

At present, although the traditional sewage treatment process based on the activated sludge method can meet the goal of meeting the water quality standards of the effluent, the organic matter in the sewage is degraded into water and CO ₂ through intensive aeration and a large amount of energy input.

Anaerobic digestion can use facultative and anaerobic bacteria to react to decompose organic matter in sludge. It is an effective way to achieve sludge stabilization, reduction, and resource utilization. Research shows that about 50% of the energy consumption in sewage treatment plants is used to supply oxygen to the aeration tank, remove organic matter in sewage and nitrify ammonia nitrogen. Only a limited part of the energy resources is captured in the form of "residual sludge". This practice not only consumes a lot of energy but also does not fully recycle energy resources.

Therefore, it is necessary to develop a sewage resource recycling method with low energy consumption, high resource utilization rate and high anaerobic digestion capacity to promote efficient recycling of sewage resources.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art, at least to a certain extent. To this end, the purpose of the present invention is to propose a method for improving the utilization of sewage resources through membrane concentration. In the present invention, sewage, adsorbent and coagulant are first mixed, and then the clear liquid and sludge mixture are separated through a membrane concentration device, and then the sludge mixture is subjected to anaerobic digestion reaction. As a result, more organic matter resources in the sewage are captured, and the anaerobic digestion capacity of the sludge is improved. The methane production per unit VS is increased by 10.2% to 31.9% compared with the primary sludge, and is increased by 7.8% to the residual sludge. 29.1%, thereby overcoming the problems of high energy consumption and insufficient resource recycling caused by continuous aeration of the traditional sewage treatment process based on the activated sludge method.

The present invention proposes a method for improving utilization of sewage resources through membrane concentration. According to an embodiment of the present invention, the method includes:

(1) Mix sewage, adsorbent and coagulant to form a mixed liquid;

(2) Pass the mixed liquid into a membrane concentration device to separate the clear liquid and sludge mixture in the mixed liquid;

(3) Mix the sludge mixture and the inoculum to perform anaerobic digestion reaction.

According to the method for improving the utilization of sewage resources through membrane concentration according to the embodiment of the present invention, sewage, adsorbent and coagulant are first mixed and then passed into the membrane concentration device to separate the clear liquid and sludge mixture, and finally the sludge mixture is processed Anaerobic digestion reaction. The adsorbent can adsorb soluble organic matter in the sewage, so that more carbon sources are trapped in the concentrated sludge, and together with the coagulant, the flocculent sludge rich in organic matter in the sewage can quickly aggregate and separate from the water phase, and effectively Slowing down membrane clogging, coagulants can also effectively remove phosphorus and metal ions in the sewage aqueous phase. Using the sludge mixture containing adsorbents and coagulants for anaerobic digestion can effectively improve anaerobic digestion efficiency and improve Methane production during anaerobic digestion. Compared with the anaerobic digestion reaction of the sludge obtained by the traditional activated sludge method, the method of improving the utilization of sewage resources through membrane concentration of the present invention captures more organic matter resources in the sewage and improves the anaerobic digestion capacity of the sludge. , the methane production per unit VS is 10.2% to 31.9% higher than that of primary sludge, and 7.8% to 29.1% higher than that of residual sludge, thereby overcoming the problem of continuous aeration caused by the traditional sewage treatment process based on the activated sludge method. problems such as high energy consumption and insufficient recycling of resources.

In addition, the method according to the above embodiments of the present invention may also have the following additional technical features:

In some embodiments of the invention, the adsorbent is activated carbon.

In some embodiments of the present invention, the coagulant is selected from at least one of polyaluminum chloride and polyferric chloride.

In some embodiments of the present invention, the content of the adsorbent in the mixed liquid is 10 mg/L to 50 mg/L.

In some embodiments of the present invention, the content of the coagulant in the mixed liquid is 10 mg/L to 50 mg/L.

In some embodiments of the present invention, in step (2), the membrane concentration device includes a mixed liquid inlet, a membrane module, a clear liquid outlet and a sludge mixture outlet, and the mixed liquid inlet is provided in the membrane concentration device On one side of the membrane concentration device, the membrane module is arranged inside the membrane concentration device, the clear liquid outlet is arranged at the upper part of the membrane concentration device away from the mixed liquid inlet, and the sludge mixture outlet is arranged at the side of the membrane concentration device away from the mixed liquid inlet. The lower part of the membrane concentration device on the side away from the mixed liquid inlet.

In some embodiments of the present invention, in step (2), the membrane concentration device further includes an aeration device, and the aeration device is disposed at the bottom of the membrane concentration device.

In some embodiments of the present invention, the membrane concentration device further includes a vacuum pump, which is used to pump the clear liquid out of the membrane concentration device.

In some embodiments of the present invention, in step (2), the residence time of the sludge mixture in the membrane concentration device is 1 to 6 days.

In some embodiments of the present invention, in step (3), the moisture content of the sludge mixture before the anaerobic digestion reaction is 92% to 98%.

In some embodiments of the present invention, centrifugal sedimentation and/or natural standing methods are used to ensure that the moisture content of the sludge mixture obtained in step (2) is in the range of 92% to 98%.

In some embodiments of the present invention, it is characterized in that in step (3), the VS ratio in the anaerobic digestion substrate and the inoculum is (1:3) to (3:1).

In some embodiments of the present invention, in step (3), the temperature of the anaerobic digestion reaction is 33°C to 37°C.

In some embodiments of the present invention, in step (3), the pH of the digestive system of the anaerobic digestion reaction is 8.0-8.1.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of the drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

Figure 1 is a schematic flow chart of a method for improving utilization of sewage resources through membrane concentration according to one embodiment of the present invention;

Figure 2 is a comparison chart of unit VS methane production of different sludges undergoing anaerobic digestion reactions according to the embodiment of the present invention;

Figure 3 is a schematic diagram of a device for preparing a sludge mixture according to an embodiment of the present invention.

Reference signs:

1-Sewage inlet, 2-Adsorbent inlet, 3-Coagulant inlet, 4-Mixing device, 5-Membrane concentration device, 6-Mixed liquid inlet, 7-Aeration device, 8-Sludge mixture outlet, 9- Membrane module, 10-vacuum pump, 11-clear liquid outlet.

Detailed ways

The embodiments of the present invention are described in detail below. Examples of the above embodiments are shown in the drawings, in which the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and are not to be construed as limiting the present invention.

The present invention proposes a method for improving utilization of sewage resources through membrane concentration. According to an embodiment of the present invention, with reference to Figure 1, the above method includes the following steps:

S100: Mix wastewater, adsorbent and coagulant

In this step, sewage, adsorbent and coagulant are mixed to form a mixed liquid.

In the embodiments of the present invention, the specific type of the above-mentioned adsorbent is not particularly limited. Persons in the art can choose according to actual needs. As a specific example, the above-mentioned adsorbent is selected from activated carbon. Therefore, most of the adsorbents in the sewage The soluble organic matter is adsorbed, allowing more carbon sources to be trapped in the concentrated sludge and effectively slowing down membrane clogging, thereby improving the separation efficiency of sludge and sewage and conducive to improving the efficiency of anaerobic digestion reactions.

In the embodiment of the present invention, the source of the above-mentioned sewage is not particularly limited and may be urban sewage or sewage from other sources.

In the embodiments of the present invention, the specific type of the above-mentioned coagulant is not particularly limited, and those in the art can select it according to actual needs. As a specific example, the above-mentioned coagulant is selected from the group consisting of polyaluminum chloride and polychlorinated At least one kind of iron is included. Therefore, phosphorus and metal salts in the sewage water phase can be effectively intercepted, recycling resources while effectively reducing membrane fouling. Preferably, the active ingredient of polyaluminum chloride is 30% AlCl ₃ .

According to a specific embodiment of the present invention, the content of the above-mentioned adsorbent in the above-mentioned mixed liquid is 10 mg/L ~ 50 mg/L. Therefore, the mass concentration of the above-mentioned adsorbent in the above-mentioned mixed liquid is limited to the above-mentioned range, It ensures that organic matter in sewage can be absorbed to the greatest extent, the organic matter recovery rate can reach 70% to 90%, and the reaction process of anaerobic digestion can be promoted to the greatest extent. The inventor found that when the content of the above-mentioned adsorbent is too low, membrane clogging is likely to occur, thereby affecting the separation efficiency of the sewage and sludge mixture, and the ability to promote the anaerobic digestion reaction is weakened. When the content of the above-mentioned adsorbent is too high, it will cause adsorption wastage of agents. During the reaction process of anaerobic digestion, the above-mentioned adsorbents can enhance the direct electron transfer between species and thereby increase the gas production potential of anaerobic digestion.

According to another specific embodiment of the present invention, the content of the above-mentioned coagulant in the above-mentioned mixed liquid is 10 mg/L ~ 50 mg/L. Therefore, the mass concentration of the above-mentioned coagulant in the above-mentioned mixed liquid is limited to the above-mentioned Within the range, it ensures that the flocs rich in organic matter in the raw sewage water can be quickly gathered and separated to the greatest extent, and the phosphorus in the sewage aqueous phase can be well removed and the reaction process of anaerobic digestion can be promoted, and the waste of coagulant can be avoided. . The inventor found that when the content of the above-mentioned coagulant is too low, the aggregation and separation efficiency of flocculent sludge rich in organic matter in the raw sewage water is greatly reduced, thus affecting the separation efficiency of the mixture of sewage and sludge. When the content of the above-mentioned coagulant is too high, it will Affects anaerobic digestion performance and causes waste of coagulant.

S200: Separating the mixture of clear liquid and sludge through membrane concentration device

In this step, the above mixed liquid is passed into the membrane concentration device. The adsorbent in the mixed liquid can adsorb the soluble organic matter in the sewage, retain more carbon sources in the concentrated sludge, and together with the coagulant, make the organic matter in the sewage Abundant flocculent sludge quickly aggregates and separates from the water phase, and effectively slows down membrane clogging. The coagulant can effectively remove phosphorus and metal ions in the sewage water phase.

According to another specific embodiment of the present invention, with reference to Figure 3, in step S200, the above-mentioned membrane concentration device 5 includes a mixed liquid inlet 6, a membrane module 9, a clear liquid outlet 11 and a sludge mixture outlet 8. The above-mentioned mixed liquid inlet 6 is arranged on one side of the above-mentioned membrane concentration device 5, the above-mentioned membrane module 9 is arranged inside the above-mentioned membrane concentration device 5, the above-mentioned clear liquid outlet 11 is arranged on the upper part of the above-mentioned membrane concentration device 5 on the side away from the above-mentioned mixed liquid inlet 6, the above-mentioned The sludge mixture outlet 8 is provided at the lower part of the membrane concentration device 5 on the side away from the mixed liquid inlet 6 . Preferably, the above-mentioned membrane module 9 is a filter layer, and the above-mentioned filter layer is arranged perpendicularly to the bottom of the above-mentioned membrane concentration device.

According to another specific embodiment of the present invention, with reference to Figure 3, in step S200, the above-mentioned membrane concentration device 5 also includes an aeration device 7, and the above-mentioned aeration device 7 is disposed at the bottom of the above-mentioned membrane concentration device 5. Therefore, The aeration device can assist the membrane module to effectively slow down membrane fouling and membrane clogging, thereby extending the use time of the membrane concentration device and improving the efficiency of the membrane concentration process.

According to another specific embodiment of the present invention, with reference to Figure 3, in step S200, the above-mentioned membrane concentration device 5 also includes a vacuum pump 10. The vacuum pump 10 is connected to the clear liquid outlet 11. The vacuum pump is used to separate the clear liquid from the above-mentioned membrane. Pull out the membrane concentration device.

According to another specific embodiment of the present invention, with reference to Figure 3, in step S200, the above-mentioned membrane concentration device 5 is provided with a mixing device 4 on a side away from the clear liquid outlet 11 and the sludge mixture outlet 8. The above-mentioned mixing device includes 4 It includes sewage inlet 1, adsorbent inlet 2 and coagulant inlet 3 to achieve better mixing of sewage, adsorbent and coagulant. Preferably, the mixing device 4 also includes a stirring pump to further ensure that the above-mentioned sewage, the above-mentioned adsorbent and the above-mentioned coagulant can be better mixed.

According to another specific embodiment of the present invention, step S200 also includes separating the sludge mixture collected from the sludge mixture outlet to reduce the water content of the sludge mixture so that the sludge mixture can satisfy anaerobic digestion. The reaction proceeds efficiently.

According to another specific embodiment of the present invention, in step S200, the residence time of the above-mentioned sludge mixture in the above-mentioned membrane concentration device is 1d to 6d. Therefore, the residence time of the above-mentioned sludge mixture in the above-mentioned membrane concentration device is limited to Within the above range, membrane clogging can be further effectively prevented and membrane concentration efficiency can be improved.

S300: Anaerobic digestion of sludge mixture

In this step, the above-mentioned sludge mixture and inoculum are mixed to perform anaerobic digestion reaction. The adsorbent in the sludge mixture will promote the efficiency of anaerobic digestion of the sludge mixture.

According to another specific embodiment of the present invention, in step S300, the moisture content of the above-mentioned sludge mixture before the anaerobic digestion reaction is 92% to 98%, thereby, the above-mentioned sludge before the anaerobic digestion reaction is The moisture content of the mixture is limited to the above range, which can further ensure the uniformity and mass transfer effect of materials in the digestive system, thereby improving the anaerobic digestion performance. Preferably, the moisture content of the above-mentioned sludge mixture before anaerobic digestion reaction is 92% to 96%.

In the embodiments of the present invention, the method for controlling the moisture content of the above-mentioned sludge mixture is not particularly limited. Persons in the art can choose according to actual needs. As a specific example, the method for controlling the moisture content of the above-mentioned sludge mixture is selected from: Centrifugal sedimentation and/or natural settling.

According to another specific embodiment of the present invention, in step S300, the VS ratio of the above-mentioned anaerobic digestion substrate and the above-mentioned inoculum is (1:3) to (3:1), whereby the anaerobic digestion substrate is The ratio to the above-mentioned inoculum is limited to the above-mentioned range, which ensures that the organic matter in the substrate can be well decomposed and utilized by microorganisms, the gas production efficiency is high, and the waste of anaerobic digestion substrate and inoculum is avoided.

According to another specific embodiment of the present invention, in step S300, the temperature of the above-mentioned anaerobic digestion reaction is 33°C to 37°C. Therefore, the temperature of the above-mentioned anaerobic digestion reaction is limited to the above-mentioned range, ensuring anaerobic The digestion reaction is carried out efficiently and the situation of inhibiting the sludge digestion speed caused by too high or too low temperature is avoided.

According to another specific embodiment of the present invention, in step S300, the pH of the above-mentioned anaerobic digestion reaction is 8.0-8.1. Therefore, the pH of the above-mentioned anaerobic digestion reaction is limited to the above-mentioned range, ensuring the anaerobic digestion reaction. It is carried out efficiently and avoids the inhibition of methanogenic bacteria, thereby affecting the stable operation of the digestive system.

According to another specific embodiment of the present invention, in step S300, the mixing method of the above-mentioned anaerobic digestion substrate and the above-mentioned inoculum is intermittent stirring and mixing, thereby further ensuring that the above-mentioned anaerobic digestion substrate and the above-mentioned inoculum are mixed. The degree of mixing can improve the efficiency of anaerobic digestion reaction.

According to the method for improving the utilization of sewage resources through membrane concentration according to the embodiment of the present invention, sewage, adsorbent and coagulant are first mixed and then passed into the membrane concentration device, and finally the sludge mixture is subjected to anaerobic digestion reaction. The adsorbent can adsorb soluble organic matter in the sewage, so that more carbon sources are trapped in the concentrated sludge, and together with the coagulant, the flocculent sludge rich in organic matter in the sewage can quickly aggregate and separate from the water phase, and effectively Slowing down membrane clogging, coagulants can also effectively remove phosphorus and metal ions in the sewage aqueous phase. Using the sludge mixture containing adsorbents and coagulants for anaerobic digestion can effectively improve anaerobic digestion efficiency and improve Methane production during anaerobic digestion. Compared with the anaerobic digestion reaction of the sludge obtained by the traditional activated sludge method, the method of improving the utilization of sewage resources through membrane concentration of the present invention captures more organic matter resources in the sewage and improves the anaerobic digestion capacity of the sludge. , the methane production per unit VS is 10.2% to 31.9% higher than that of primary sludge, and 7.8% to 29.1% higher than that of residual sludge, thereby overcoming the problem of continuous aeration caused by the traditional sewage treatment process based on the activated sludge method. problems such as high energy consumption and insufficient recycling of resources.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above-mentioned embodiments are illustrative and should not be construed as limitations of the present invention. Those of ordinary skill in the art can make modifications to the above-mentioned embodiments within the scope of the present invention. The embodiments are subject to changes, modifications, substitutions and variations.

In all the following examples and comparative examples, the following conditions remain consistent:

The generation device of the anaerobic digestion experiment mainly includes a water bath heater, anaerobic digestion bottle, automatic stirrer, CO ₂ absorption unit, gas collection and methane measurement unit and data acquisition unit. The digestion bottle volume is 500mL, and the digestion bottle working volume is 400mL. , the inoculum is taken from the anaerobic digestion tank of the sewage treatment plant, VS _substrate : VS _inoculum = 2:1, after adding the substrate and inoculum, seal it with a rubber stopper and expose it to nitrogen for 5 minutes. pH of the digestive system during the digestion reaction is 8.0, with intermittent stirring, the stirring rate is 150r/min, the stirring time interval is 15min, and the stirring time once is 30s.

Example 1

A method for improving wastewater resource utilization through membrane concentration, including the following steps:

(1) Establish a mixing device and a membrane concentration device;

(2) Mix 25 mg/L activated carbon, 25 mg/L polyaluminum chloride and 1L sewage in a mixing device. Use a pump to stir during the mixing period, and then put the mixed solution into the membrane concentration tank, and the membrane effluent will be instantaneous through the vacuum pump It is discharged from the clear liquid outlet, and at the same time, the membrane concentrated raw mud (i.e. sludge mixture, with a moisture content of 96%) is collected at the bottom of the membrane concentration tank;

(3) Take the membrane-concentrated sludge mixture with SRT=6d and perform centrifugal concentration at 8000r/min, and then pour out part of the supernatant, so that the moisture content of the membrane-concentrated sludge mixture is 92%, 94%, and 96% respectively;

(4) Take the above-mentioned membrane concentrated sludge with SRT=6d and moisture content of 92% for anaerobic digestion to produce biogas, and anaerobically digest it for 30 days at a reaction temperature of 35°C; take the above-mentioned SRT=6d with a moisture content of 92%. 94% of the membrane-concentrated sludge is subjected to anaerobic digestion to produce biogas, and the reaction temperature is 35°C for 30 days; take the membrane-concentrated raw sludge with SRT=6d for anaerobic digestion to produce biogas, and the reaction temperature is 35°C. Anaerobic digestion for 30 days at 35°C, membrane concentrated sludge with SRT=6d and moisture content of 92%, membrane concentrated sludge with SRT=6d and moisture content of 94%, and membrane concentrated raw mud with SRT=6d Carry out unit VS methane production test, and the test results are shown in Figure 2.

Example 2

A method to improve energy recovery of wastewater resources through membrane concentration, including:

(1) Establish a mixing device and a membrane concentration device;

(2) Mix 25 mg/L activated carbon, 25 mg/L polyaluminum chloride and 1L sewage in a mixing device. Use a pump to stir during the mixing period, and then put the mixed solution into the membrane concentration tank, and the membrane effluent will be instantaneous through the vacuum pump It is discharged from the clear liquid outlet, and at the same time, the membrane concentrated raw mud (i.e. sludge mixture, with a moisture content of 98%) is collected at the bottom of the membrane concentration tank;

(3) Take the membrane-concentrated sludge mixture with SRT=6d and perform centrifugal concentration at 8000r/min, and then pour out part of the supernatant, so that the moisture content of the membrane-concentrated sludge mixture is 92%, 94%, and 96% respectively;

(4) Take the above membrane concentrated sludge with SRT=4d and moisture content of 92% for anaerobic digestion reaction to produce biogas. Anaerobically digest it for 30 days at a reaction temperature of 35°C; take the above SRT=4d with moisture content of 92%. 94% of the membrane-concentrated sludge is subjected to anaerobic digestion to produce biogas, and the reaction temperature is 35°C for anaerobic digestion for 30 days; take the above-mentioned membrane-concentrated sludge with SRT=4d and a moisture content of 96% for anaerobic digestion. Produce biogas; take the above-mentioned membrane concentrated sludge with SRT=4d for anaerobic digestion to produce biogas. Anaerobically digest it for 30 days at a reaction temperature of 35°C. For the membrane concentrated sludge with SRT=4d and moisture content of 92%, , membrane concentrated sludge with SRT=4d and moisture content of 94%, membrane concentrated sludge with SRT=4d and moisture content of 96%, and membrane concentrated raw sludge with SRT=4d were tested for unit VS methane production. The test results are as follows As shown in Figure 2.

Example 3

A method to improve energy recovery of wastewater resources through membrane concentration, including:

(1) Establish a mixing device and a membrane concentration device;

(2) Mix 25 mg/L activated carbon, 25 mg/L polyaluminum chloride and 1L sewage in a mixing device. Use a pump to stir during the mixing period, and then put the mixed solution into the membrane concentration tank, and the membrane effluent will be instantaneous through the vacuum pump It is discharged from the clear liquid outlet, and at the same time, the membrane concentrated raw mud (i.e. sludge mixture, with a moisture content of 98.6%) is collected at the bottom of the membrane concentration tank;

(3) Take the membrane-concentrated sludge mixture with SRT=6d and perform centrifugal concentration at 8000r/min, and then pour out part of the supernatant, so that the moisture content of the membrane-concentrated sludge mixture is 92%, 94%, and 96% respectively;

(4) Take the above membrane concentrated sludge with SRT=2d and moisture content of 92% for anaerobic digestion reaction to produce biogas, and anaerobically digest it for 30 days at a reaction temperature of 35°C; take the above SRT=2d with moisture content of 92%. 94% of the membrane-concentrated sludge is subjected to anaerobic digestion to produce biogas, and the reaction temperature is 35°C for anaerobic digestion for 30 days; take the above-mentioned membrane-concentrated sludge with SRT=2d and a moisture content of 96% for anaerobic digestion. Produce biogas; take the above-mentioned membrane concentrated sludge with SRT=2d for anaerobic digestion to produce biogas. Anaerobically digest it for 30 days at a reaction temperature of 35°C. For membrane concentrated sludge with SRT=2d and a moisture content of 92% , membrane concentrated sludge with SRT=2d and moisture content of 94%, membrane concentrated sludge with SRT=2d and moisture content of 96%, and membrane concentrated raw sludge with SRT=2d were tested for unit VS methane production. The test results are as follows As shown in Figure 2.

Comparative example 1

(1) The primary sludge is directly precipitated by sewage from the sewage inlet of the membrane concentration device. After pouring off the supernatant, perform centrifugal concentration at 8000r/min and pour off part of the supernatant to make the moisture content 94%.

(2) Take the above-mentioned primary sedimentation sludge with a moisture content of 94% for anaerobic digestion to produce biogas. As shown in Figure 2, the membrane concentrated sewage was subjected to anaerobic digestion for 30 days at a reaction temperature of 35°C and SRT=2d. Methane production per mud unit VS is 155.7mL/gVS.

Comparative example 2

(1) The remaining sludge is taken from a sewage treatment plant treated by the traditional activated sludge method. After retrieval, it is centrifuged and concentrated at 8000r/min, and part of the supernatant is poured off to make the moisture content 94%.

(2) Take the above-mentioned remaining sludge with a moisture content of 94% for anaerobic digestion to produce biogas. As shown in Figure 2, anaerobic digestion for 30 days at a reaction temperature of 35°C and membrane concentrated sludge with SRT = 2d Methane production per mud unit VS is 159.1mL/gVS.

It can be seen from Figure 2 that in Example 1, the membrane concentrated sludge with SRT=6d and moisture content of 92%, the membrane concentrated sludge with SRT=6d and moisture content of 94%, and the membrane concentrated raw material with SRT=6d The unit VS methane production amount of the mud was 199.3mL/gVS, 202.9mL/gVS and 183.1mL/gVS respectively. Compared with the unit VS methane production amount of the primary sedimentation sludge of Comparative Example 1, they increased by 28.0% and 30.3% respectively. and 17.6%. Compared with the unit VS methane production amount of the remaining sludge in Comparative Example 2, they increased by 25.2%, 27.5% and 15.1% respectively.

In the same way, it can be seen that the membrane concentrated sludge with SRT=4d and the moisture content in Example 2 is 92%, the membrane concentrated sludge with SRT=4d and the moisture content is 94%, and the membrane concentrated sludge with SRT=4d and the moisture content is 96%. The methane production per unit VS of the membrane concentrated sludge and the membrane concentrated raw sludge with SRT=4d were 200.5mL/gVS, 205.3mL/gVS, 187.2mL/gVS and 174.1mL/gVS respectively. Compared with the initial value of Comparative Example 1 The unit VS methane production of the settled sludge increased by 28.8%, 31.9%, 20.2% and 11.9% respectively. Compared with the remaining sludge of Comparative Example 2, the unit VS methane production increased by 26.0% and 29.1% respectively. , 17.7% and 9.5%.

In the same way, it can be seen that the membrane concentrated sludge with SRT=4d and the moisture content in Example 3 is 92%, the membrane concentrated sludge with SRT=4d and the moisture content is 94%, and the membrane concentrated sludge with SRT=4d and the moisture content is 96%. The methane production per unit VS of the membrane concentrated sludge and the membrane concentrated raw sludge with SRT=4d were 194.8mL/gVS, 196.9mL/gVS, 182.2mL/gVS and 171.5mL/gVS respectively. Compared with the initial value of Comparative Example 1 The unit VS methane production of the settled sludge increased by 25.1%, 26.5%, 17.0% and 10.2% respectively. Compared with the unit VS methane production of the remaining sludge in Comparative Example 2, it increased by 22.4% and 23.8% respectively. , 14.5% and 7.8%.

It should be explained that in this application, the reason why the unit VS methane production amount of the remaining sludge in Comparative Example 2 is greater than the unit VS methane production amount of the primary sedimentation sludge in Comparative Example 1 is:

Under normal circumstances, the unit VS methane production of the remaining sludge should be smaller than the unit VS methane production of the primary sludge. The primary sludge and remaining sludge in this application use different sludge raw materials. Examples 1 to 3 and The sewage used in Comparative Example 1 came from the same sewage treatment plant, where VSS:TSS=48.9%-57.2%; the sewage used in Comparative Example 2 came from another sewage treatment plant, where VSS:TSS=64.1%.

The organic matter content will affect the methane production amount of the sludge. The higher the organic matter content, the higher the methane production amount. The lower the organic matter content, the lower the methane production amount. Therefore, in the present application, the unit VS methane production of the remaining sludge in Comparative Example 2 is The amount is slightly larger than the unit VS methane production amount of the primary sludge of Comparative Example 1. However, this does not affect the methane production per unit VS of the membrane concentrated sludge of the present application, which is significantly improved compared to the methane production per unit VS of the primary sludge and residual sludge.

For those of ordinary skill in the art, based on the above principles, several changes and improvements can be made to the method of the present invention, and these changes and improvements should also be included in the protection scope of the present invention.

Claims (5)

1. A method for improving wastewater resource utilization by membrane concentration, comprising:

(1) Mixing the sewage, the adsorbent and the coagulant to form a mixed solution;

(2) Introducing the mixed liquor into a membrane concentration device so as to separate clear liquid in the mixed liquor from a sludge mixture;

(3) Mixing the sludge mixture with the inoculum, and performing anaerobic digestion reaction;

the adsorbent is activated carbon;

the coagulant is at least one selected from polyaluminum chloride and ferric chloride;

the content of the adsorbent in the mixed solution is 10 mg/L-50 mg/L;

the content of the coagulant in the mixed solution is 10 mg/L-50 mg/L;

the ratio of VS in the anaerobically digested substrate and the inoculum is (1:3) - (3:1);

the temperature of the anaerobic digestion reaction is 33-37 ℃;

the pH of the digestion system of the anaerobic digestion reaction is 8.0-8.1.

2. The method according to claim 1, wherein in the step (2), the membrane concentration device includes a mixed liquor inlet provided on one side of the membrane concentration device, a membrane module provided inside the membrane concentration device, a clear liquor outlet provided on an upper portion of the side of the membrane concentration device remote from the mixed liquor inlet, and a sludge mixture outlet provided on a lower portion of the side of the membrane concentration device remote from the mixed liquor inlet.

3. The method of claim 2, wherein in step (2), the membrane concentration device further comprises an aeration device disposed at a bottom of the membrane concentration device;

optionally, the membrane concentration device further comprises a vacuum pump for pumping the clear liquid out of the membrane concentration device.

4. The method of claim 1, wherein in step (2), the residence time of the sludge mixture in the membrane concentration device is 1d to 6d.

5. The method according to claim 1, wherein in step (3), the water content of the sludge mixture before the anaerobic digestion reaction is 92% to 98%;

optionally, the centrifugal sedimentation and/or natural standing method is used to ensure that the water content of the sludge mixture obtained in the step (2) is in the range of 92-98%.