CN111500646A - A kind of method for producing methane from phenol-containing wastewater - Google Patents

Abstract

The invention discloses a method for producing methane from phenol-containing waste water, which comprises the following steps: introducing phenolic wastewater added with a co-metabolism matrix into an anaerobic reactor to perform anaerobic reaction by taking the phenolic wastewater as a water inlet sample; collecting the generated gas while refluxing a portion of the effluent to the influent at a reflux ratio of 0.42-0.55; wherein, graphene is added into the anaerobic reactor. The method for producing methane from the phenolic wastewater realizes the improvement of the yield of methane generated by anaerobic digestion of the phenolic wastewater.

Description

A kind of method for producing methane from phenol-containing wastewater

technical field

The invention relates to the technical field of wastewater treatment, in particular to a method for producing methane from phenol-containing wastewater.

Background technique

As an industrial raw material, phenolic compounds are widely used in petrochemical, printing and dyeing, textile, pesticide, biomedicine and other industries. It is also a relatively common pollutant in industrial wastewater. Even at low concentrations, it can have a huge toxic effect on humans and microorganisms, with very detrimental effects on the human environment. These phenolic pollutants are not only difficult to be biodegraded by themselves, but also have a serious inhibitory effect on microorganisms, affecting the removal of other pollutants in wastewater.

Anaerobic biological treatment technology is the process by which facultative anaerobic and anaerobic microbial populations convert organic matter into methane and carbon dioxide under anaerobic conditions. The anaerobic process can improve the biodegradability of wastewater, generate less excess sludge, and have low investment costs, and is an important link in the biological treatment process of coal gasification wastewater. The removal or conversion of phenolic substances can be achieved through anaerobic digestion, and the biodegradability of wastewater is improved, which is beneficial to the subsequent degradation of aerobic organisms.

The Chinese patent with publication number CN110606562A (published on December 24, 2019) discloses a method for producing methane from high-concentration phenol-containing wastewater, which applies anaerobic co-metabolism enhancement technology and graphene to wastewater anaerobic treatment In the process of anaerobic digestion of phenol-containing wastewater, the increase of methane production was realized. However, the methane yield of this method still needs to be improved.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for producing methane from phenol-containing wastewater, and the method realizes the improvement of the methane production by anaerobic digestion of phenol-containing wastewater.

In order to solve the above-mentioned technical problems, the present invention provides the following technical solutions:

The invention provides a method for producing methane from phenol-containing wastewater, comprising:

Take the phenol-containing wastewater added with the co-metabolized substrate as the influent water sample, and pass it into the anaerobic reactor for anaerobic reaction; collect the generated gas, and return a part of the effluent to the influent at a reflux ratio of 0.42-0.55; Wherein, graphene is added into the anaerobic reactor.

Further, the total phenol concentration in the phenol-containing wastewater is greater than or equal to 500 mg/L.

Further, the dosage of the graphene is 8.8-11.2g/L.

Further, the co-metabolized substrate is glucose.

Further, the influent water sample is a mixed solution of phenol-containing wastewater and glucose solution.

Further, the volume ratio of the phenol-containing wastewater and the glucose solution is 1:1, and the concentration of the glucose solution is 1882-2120 mg/L.

Further, the effluent reflux ratio of the anaerobic reactor is 0.5.

Further, the hydraulic retention time of the anaerobic reactor is within 48h.

Further, the anaerobic reactor is provided with interlayer circulating water, and the temperature for controlling the anaerobic reaction is 35°C.

Further, the suspended matter concentration of the total inoculated sludge in the anaerobic reactor is 86.08g/L, the volatile suspended matter concentration is 78g/L, and the inoculation amount is 30% of the effective volume of the anaerobic reactor.

Beneficial effects of the present invention:

1. The present invention returns a part of the effluent to the influent, on the one hand, the reflux can dilute the phenol concentration in the influent, weaken the inhibitory effect on methanogens, and on the other hand, the hydraulic shear force generated in the reflux process promotes anaerobic microorganisms. At the same time, the reflux can also disperse the agglomerated graphene; through the comprehensive effect of the reflux, the efficiency of methane production is improved.

2. The results of the small test show that when graphene is added to the anaerobic reactor and under the condition of anaerobic co-metabolism of glucose, when the reflux ratio is 0, the methane output of the system is about 525 mL/day; when the reflux ratio is 0.5, The methane production of the system increased by about 100mL/day; when the effluent reflux ratio was further increased to 1, the methane production dropped sharply.

Description of drawings

Fig. 1 is the operating device diagram of the anaerobic reactor in the present invention;

Figure 2 shows the methane production of the phenol-containing wastewater treated by the anaerobic reactor under different reflux ratios.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As described in the background art, the methane yield of the existing method for producing methane from phenol-containing wastewater needs to be further improved.

In order to solve this technical problem, the present invention provides a method for producing methane from phenol-containing wastewater. Anaerobic reaction is carried out in (UASB); the generated gas is collected, and a part of the effluent is refluxed to the influent at a reflux ratio of 0.42-0.55; wherein, graphene is added into the anaerobic reactor.

In the present invention, the phenol-containing wastewater may contain phenolic compounds such as phenol, catechol, resorcinol, hydroquinone, etc., and it is preferably high-concentration phenol-containing wastewater with a total phenol concentration ≥ 500 mg/L.

Co-metabolic substrates are very important for the degradation of refractory substances, because the non-specific key enzymes produced during the reaction are competitively inhibited between the growth substrate and the non-growth substrate. When more growth substrates are added, the number of key enzymes produced by microorganisms is also more, and the degradation effect of target pollutants is also better. In the present invention, the co-metabolism substrate is preferably glucose, which has low cost and is easily degraded by microorganisms and can provide electrons for the reaction system.

In the present invention, glucose can be added to the phenol-containing wastewater in the form of solution or powder. Preferably, the influent water sample is a mixture of phenol-containing wastewater and glucose solution (GW). Further preferably, the volume ratio of the phenol-containing wastewater and the glucose solution is 1:1. The concentration of the glucose solution is preferably 1882-2120 mg/L, more preferably 2000 mg/L.

Graphene can improve the dispersion of the catalyst, promote the electronic conductivity, and strengthen the adsorption of pollutants, thereby improving the stability and efficiency of the catalytic oxidation system. By adding graphene in the anaerobic reactor, on the one hand, some toxic substances and refractory substances can be removed by the adsorption of graphene; on the other hand, graphene is beneficial to the electron transfer in the redox process between anaerobic microorganisms, It can greatly increase the efficiency of methane production from anaerobic granular sludge. In the present invention, the dosage of graphene in the anaerobic reactor is 8.8-11.2 g/L, preferably 9.8-10.3 g/L, more preferably 10 g/L. It should be pointed out that the concentration here is relative to the volume of the anaerobic reactor.

Due to the high concentration of phenolic compounds in the influent water, the growth of methanogens will be inhibited; at the same time, the graphene in the anaerobic reactor is easy to aggregate, thus affecting the efficiency of catalytic methane production. In the present invention, the strategy of effluent reflux is adopted, and part of the effluent is returned to the influent, which can not only dilute the concentration of phenolic compounds in the influent, and weaken the inhibitory effect of the concentration on methanogens; but also through appropriate hydraulic shear force It can promote the metabolism of anaerobic microorganisms and help the growth and reproduction of anaerobic microorganisms in the system; in addition, a certain proportion of backflow helps to disperse graphene and avoid graphene aggregation. Through the above comprehensive effects, the efficiency of methane production can be significantly improved. Among them, the reflux ratio needs to be controlled between 0.42-0.55, too high or too low will affect the efficiency of methane production, preferably the reflux ratio is 0.5.

In the present invention, the hydraulic retention time (HRT) of the anaerobic reactor is preferably within 48h. The refractory substances in the wastewater are efficiently hydrolyzed and acidified with the glucose co-substrate in a short hydraulic retention time. By adding graphene, the electron transfer in the system is accelerated, and methane can be efficiently produced under the action of methanogens.

In order to maintain the anaerobic reactor for anaerobic digestion and degradation under the condition of medium temperature, preferably, the anaerobic reactor is provided with interlayer circulating water, which is used to keep the anaerobic digestion reaction at a suitable temperature. The anaerobic reaction temperature is preferably 35°C.

In the present invention, the suspended solids concentration (SS) of the total inoculated sludge of the reactor is preferably 86.08 g/L, the volatile suspended solids concentration (VSS) is preferably 78 g/L, VSS/SS=90%, and the inoculum amount It is preferably 30% of the effective volume of the reactor.

The gas produced by the anaerobic reactor includes not only methane, but also acid gases such as CO ₂ and H ₂ S. Therefore, it is necessary to process the collected gas to remove the acid gas therein. In one embodiment, the collected gas is passed into the lye to remove acid gas therein. Of course, in other embodiments, other methods can also be used to remove acid gas.

The experimental methods used in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial sources unless otherwise specified.

Example 1

Referring to Figure 1, the mixed solution (GW+CGW, volume ratio of 1:1) of high-concentration phenol-containing wastewater and glucose solution (COD=2000mg/L) was used as the influent water sample, which was entered from the bottom of the UASB reactor, and at the same time The concentration of graphene added in the reactor is 10g/L, and the system HRT is maintained for 48 hours. The wastewater passes through the co-metabolism of glucose substrate and the adsorption of graphene and promotes the electron transfer of anaerobic microorganisms. The treated wastewater finally flows out from the top, Part of the effluent is returned to the influent, and the effluent reflux ratio is R=0.5. The generated methane gas is collected after passing through the liquid-sealed bottle and the lye absorption bottle.

Comparative Example 1

Take the mixed solution (GW+CGW, volume ratio of 1:1) of high-concentration phenol-containing wastewater and glucose solution (COD=2000mg/L) as the influent water sample, which enters from the bottom of the UASB reactor, and at the same time, it is poured into the reactor. The concentration of graphene added is 10g/L, and the system HRT is maintained for 48 hours. The wastewater passes through the co-metabolism of glucose substrate and the adsorption of graphene and promotes the electron transfer of anaerobic microorganisms. The treated wastewater finally flows out from the top, and the effluent reflux ratio is R. =0. The generated methane gas is collected after passing through the liquid-sealed bottle and the lye absorption bottle.

Comparative Example 2

Take the mixed solution (GW+CGW, volume ratio of 1:1) of high-concentration phenol-containing wastewater and glucose solution (COD=2000mg/L) as the influent water sample, which enters from the bottom of the UASB reactor, and at the same time, it is poured into the reactor. The concentration of graphene added is 10g/L, and the system HRT is maintained for 48 hours. The wastewater passes through the co-metabolism of glucose substrate and the adsorption of graphene and promotes the electron transfer of anaerobic microorganisms. The treated wastewater finally flows out from the top, and part of the effluent flows back. To the influent, the effluent reflux ratio R=1. The generated methane gas is collected after passing through the liquid-sealed bottle and the lye absorption bottle.

The methane production in Example 1, Comparative Examples 1 and 2 was investigated, and the results obtained are shown in FIG. 2 .

The results show that when the reflux ratio is 0, the methane production of the system is about 525mL/day; when the reflux ratio is 0.5, the methane production of the system increases by about 100mL/day; when the effluent reflux ratio is further increased to 1, the methane production sharply increases decline. This shows that by controlling the appropriate reflux ratio, the amount of methane production can be significantly increased.

To sum up, under the conditions that the effluent reflux ratio is 0.5, the addition amount of graphene is 9.8-10.3g/L, and the addition amount of glucose is 1865mg/L-2130mg/L, the method of the present invention can obtain the best methane yield.

The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims (10)

1. The method for producing methane from phenol-containing waste water is characterized by comprising the following steps:

introducing phenolic wastewater added with a co-metabolism matrix into an anaerobic reactor to perform anaerobic reaction by taking the phenolic wastewater as a water inlet sample; collecting the generated gas while refluxing a portion of the effluent to the influent at a reflux ratio of 0.42-0.55; wherein, graphene is added into the anaerobic reactor.

2. The method for producing methane from phenol-containing waste water according to claim 1, wherein the concentration of total phenols in the phenol-containing waste water is not less than 500 mg/L.

3. The method for producing methane from phenol-containing waste water according to claim 1, wherein the graphene is added in an amount of 8.8-11.2 g/L.

4. The method for producing methane from phenolic waste water according to claim 1, wherein the co-metabolic substrate is glucose.

5. The method for producing methane from phenolic waste water according to claim 4, wherein the inlet water sample is a mixture of phenolic waste water and glucose solution.

6. The method for producing methane from phenolic waste water as claimed in claim 5, wherein the volume ratio of the phenolic waste water to the glucose solution is 1:1, and the concentration of the glucose solution is 1882-.

7. The method for producing methane from phenol-containing waste water according to claim 1, wherein the effluent reflux ratio of the anaerobic reactor is 0.5.

8. The method for producing methane from phenolic waste water according to claim 1, wherein the hydraulic retention time of the anaerobic reactor is within 48 h.

9. The method for producing methane from phenolic waste water according to claim 1, wherein the anaerobic reactor is provided with interlayer circulating water for controlling the temperature of the anaerobic reaction to 35 ℃.

10. The method for producing methane from phenolic waste water according to claim 1, wherein the concentration of suspended matters in the total inoculated sludge in the anaerobic reactor is 86.08 g/L, the concentration of volatile suspended matters is 78 g/L, and the inoculation amount is 30% of the effective volume of the anaerobic reactor.

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