Anaerobic digestion method of distillation wastewater in straw ethanol production

Abstract

The application discloses an anaerobic digestion method for distillation wastewater in straw ethanol preparation and belongs to the technical field of wastewater treatment. The anaerobic digestion method comprises the following steps: sending the distillation wastewater in straw ethanol preparation into an acidification phase, and performing an acid production reaction under the condition that air is introduced and gas in the acidification phase is circulated; performing precipitation and layering on pretreated wastewater after the acid production reaction; taking supernatant in the pretreated wastewater after the precipitation and layering, and sending the supernatant into a methane production phase to perform a methane production reaction. The anaerobic digestion method for the distillation wastewater in straw ethanol preparation directly uses the distillation wastewater in straw ethanol preparation as raw material, adopts an anaerobic acidification-methane production phase combined treatment mode, does not need chemical precipitation and other pre-desulfurization treatments, can reduce the inhibition of H2S, improves the removal of COD in the distillation wastewater by more than 85-90%, and has obvious wastewater treatment effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to an anaerobic digestion method for distillation wastewater in straw ethanol preparation. BACKGROUND

[0002] Using agricultural straw biomass as raw material to produce biofuels and bio-based chemicals can solve the problems of high carbon emissions and environmental pollution caused by the consumption of fossil resources. At present, after obtaining fermentable sugars from straw through pretreatment / hydrolysis, fermentable sugars are further used to convert biofuels and bio-based chemicals. Among them, the preparation of fermentable sugars based on sulfuric acid assisted pretreatment / hydrolysis is a common method. However, a large amount of high-COD and high-sulfur distillation wastewater needs to be treated after the distillation of the process products.

[0003] Generally speaking, these high-sulfur wastewater is first treated by anaerobic digestion to produce biogas, and then further treated. Under anaerobic conditions, sulfate-reducing bacteria convert sulfate to sulfide (H2S), but H2S can penetrate the cell membrane and cause inactivation of microbial-related enzymes and proteins, especially sensitive methanogenic archaea, thereby inhibiting the degradation of organic matter and sulfate, causing the collapse of the anaerobic digestion system; on the other hand, the organic matter in the distillation wastewater is prone to acidification, which causes methanogenesis inhibition and process failure, and traditional anaerobic digestion reaction cannot effectively treat such wastewater, so innovative processes are needed to effectively treat such distillation wastewater in straw ethanol preparation. SUMMARY

[0004] The present application aims to provide an anaerobic digestion method for distillation wastewater in straw ethanol preparation to solve the problem of difficult treatment of high-COD and high-sulfur distillation wastewater in straw ethanol preparation.

[0005] The technical solution of the present application to solve the above technical problems is as follows:

[0006] The present application provides an anaerobic digestion method for distillation wastewater in straw ethanol preparation, which comprises:

[0007] The distillation wastewater in straw ethanol preparation is sent into the acidification phase, and the acidification reaction is carried out under the conditions of passing in a small amount of air and circulating the gas in the acidification phase;

[0008] The pretreated wastewater after acidification reaction is precipitated and layered;

[0009] The supernatant of the pretreated wastewater after precipitation and layering is taken and sent into the methanogenesis phase for methanogenesis reaction.

[0010] Further, in the anaerobic digestion method for distillation wastewater in straw ethanol preparation, the seed sludge of the acidification phase is organic wastewater anaerobic treatment granular sludge.

[0011] Further, in the anaerobic digestion method of distillation wastewater in the production of straw ethanol, the temperature for acid production reaction is 35-37°C or 53-55°C.

[0012] Further, in the anaerobic digestion method of distillation wastewater in the production of straw ethanol, the acid production reaction includes:

[0013] The flow rate of air is 5-15 mL / L / min;

[0014] And / or, the flow rate of gas circulation in the acidification phase is 0.5-4 L / L / min;

[0015] And / or, the stirring speed is 60-100 rpm;

[0016] And / or, the liquid circulation amount is 50-100 L / L / d;

[0017] And / or, the acidification treatment adopts the in-out feeding mode of day in and day out;

[0018] And / or, the hydraulic retention time is 1-4 days.

[0019] Further, in the anaerobic digestion method of distillation wastewater in the production of straw ethanol, the acid production reaction further includes: the redox potential of the liquid in the acidification phase is -300 to -200 mV;

[0020] And / or, the pH value of the liquid in the acidification phase is 5-12.

[0021] Further, in the anaerobic digestion method of distillation wastewater in the production of straw ethanol, in the anaerobic digestion method, the judgment for stopping the continuous air supply is:

[0022] When the redox potential of the liquid in the acidification phase is greater than or equal to -200 mV;

[0023] And / or, when the oxygen content in the gas produced by the acidification phase is greater than or equal to 1%.

[0024] Further, in the anaerobic digestion method of distillation wastewater in the production of straw ethanol, the precipitation time of the pretreated wastewater is 60-120 min.

[0025] Further, in the anaerobic digestion method of distillation wastewater in the production of straw ethanol, the seed sludge of the methanogenic phase is organic wastewater anaerobic treatment granular sludge.

[0026] Further, in the anaerobic digestion method of distillation wastewater in the straw ethanol production, the liquid supply flow rate of the supernatant into the methanogenic phase is 0.05 L / L / d-0.1 L / L / d.

[0027] Further, in the anaerobic digestion method of distillation wastewater in the straw ethanol production, the anaerobic digestion method further comprises: returning the sludge in the lower layer treated by the sedimentation and layering to the acidification phase.

[0028] The present application has the following beneficial effects:

[0029] The anaerobic digestion method of distillation wastewater in the straw ethanol production provided by the present application directly uses the distillation wastewater in the straw ethanol production as raw material, adopts the anaerobic acidification-methanogenic phase combination treatment mode, and does not need chemical precipitation and other pre-desulfurization treatments, so that the inhibition of H2S is reduced, the COD removal in the distillation wastewater is increased by more than 85-90%, and the wastewater treatment effect is obvious. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor. In the drawings:

[0031] Figure 1 The flow chart of the anaerobic digestion method of distillation wastewater in the straw ethanol production provided by the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0034] The technical solutions of the present application are:

[0035] Please refer to Figure 1As shown, an anaerobic digestion method for distillation wastewater in straw ethanol production is disclosed, the anaerobic digestion method comprising:

[0036] Step S1: The distillation wastewater from the straw ethanol preparation is fed into the acidification phase, and the acidification reaction is carried out under the conditions of air introduction and gas circulation within the acidification phase;

[0037] Step S2: The pretreated wastewater after acidification reaction undergoes sedimentation and stratification;

[0038] Step S3: Take the supernatant from the pretreated wastewater after sedimentation and stratification, and send it into the methanogenic phase to carry out the methanogenic reaction.

[0039] Targeting high COD, high sulfur content, and COD / SO4 2- The anaerobic digestion method of this invention directly uses the distillation wastewater from straw ethanol production as raw material, employing a combined anaerobic acidification and methanogenesis treatment method. This eliminates the need for pre-desulfurization treatments such as chemical precipitation, thereby reducing H2S inhibition and increasing COD removal from the distillation wastewater by over 85-90%, resulting in a significant wastewater treatment effect.

[0040] In the anaerobic acidification reaction of this invention, in-situ desulfurization occurs through a combination of acidification phase coupling micro-aeration (air flow rate of 5 mL / L / min ~ 15 mL / L / min) and gas circulation. The H2S in the produced gas is oxidized to elemental sulfur and enters the sludge sediment, thus avoiding the inhibition of H2S on the acidification phase microorganisms and converting organic matter in the wastewater into volatile fatty acids. Simultaneously, the sulfur-containing sludge in the acidification phase does not enter the subsequent methanogenic phase, thereby mitigating H2S inhibition during methanogenic fermentation. Therefore, the anaerobic acidification reaction of this invention reduces H2S inhibition and improves wastewater treatment efficiency.

[0041] In the anaerobic digestion method of the present invention, the COD in the distillation waste liquid undergoes an acidification reaction in the acidification phase and is converted into volatile fatty acids, providing an easily usable substrate for biogas production in the subsequent methanogenic phase, and avoiding excessive acidification of the methanogenic phase, which could lead to an imbalance between acid production and methanogenesis and cause reaction failure.

[0042] In the anaerobic digestion method of the present invention, the redox potential of the liquid in the acidification phase is controlled at -300mv to -200mv. Based on this, the flow rate of air supplied into the reactor can be automatically adjusted, which can more effectively reduce the inhibition of acidification and methanogenesis by H2S, thereby promoting the efficiency of methane fermentation.

[0043] Furthermore, the acidified seed sludge is treated with organic wastewater using anaerobic methods to produce granular sludge.

[0044] Further, the temperature for carrying out the acid production reaction is 35-37℃, which can be 35℃, 35.3℃, 35.5℃, 35.7℃, 36℃, 36.3℃, 36.5℃, 36.7℃, 37℃, etc.; or 53-55℃, which can be 53℃, 53.3℃, 53.5℃, 53.7℃, 54℃, 54.3℃, 54.5℃, 54.7℃, 55℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0045] Further, the acid production reaction includes:

[0046] The flow rate of air introduced is 5-15 mL / L / min, which can be 5 mL / L / min, 7 mL / L / min, 10 mL / L / min, 11 mL / L / min, 12 mL / L / min, 13 mL / L / min, 14 mL / L / min, 15 mL / L / min, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0047] The flow rate of gas circulation in the acidification phase is 0.5-4 L / L / min, which can be 0.5 L / L / min, 0.7 L / L / min, 1 L / L / min, 1.5 L / L / min, 2 L / L / min, 2.5 L / L / min, 3 L / L / min, 3.5 L / L / min, 4 L / L / min, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0048] And / or, the stirring speed is 60-100 rpm, which can be 60 rpm, 65 rpm, 70 rpm, 75 rpm, 80 rpm, 85 rpm, 90 rpm, 95 rpm, 100 rpm, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0049] And / or, the liquid circulation amount is 50-100 L / L / d, which can be 50 L / L / d, 55 L / L / d, 60 L / L / d, 67 L / L / d, 75 L / L / d, 85 L / L / d, 95 L / L / d, 100 L / L / d, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0050] And / or, the acidification treatment adopts a day-in day-out feeding and discharging mode;

[0051] And / or, the hydraulic retention time is 1-4 days, which can be 1 day, 2 days, 3 days, 4 days, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0052] Further, the acidogenic reaction also includes that the redox potential of the liquid in the acidification phase is -300 mv to -200 mv, which can be -300 mv, -290 mv, -280 mv, -270 mv, -260 mv, -250 mv, -240 mv, -230 mv, -220 mv, -210 mv, -200 mv, and the like, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0053] Further, the pH value of the liquid in the acidification phase is 5 to 12.

[0054] Further, in the anaerobic digestion method, the judgment for stopping the continuous air supply is:

[0055] When the redox potential of the liquid in the acidification phase is greater than or equal to -200 mv;

[0056] Further, the pH value of the liquid in the acidification phase is 5 to 12.

[0057] Further, the time for the pretreated wastewater precipitation is 60 min to 120 min, which can be 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, and the like, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0058] Further, the seed sludge in the methanogenic phase is organic wastewater anaerobic treatment granular sludge.

[0059] Further, the liquid supply flow rate of the supernatant into the methanogenic phase is 0.05 L / L / d to 0.1 L / L / d, which can be 0.05 L / L / d, 0.06 L / L / d, 0.07 L / L / d, 0.08 L / L / d, 0.09 L / L / d, 0.1 L / L / d, and the like, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0060] Further, the anaerobic digestion method further includes that the lower layer sludge treated by the sedimentation and layering process is returned to the acidification phase. The precipitated lower layer sludge is supplemented according to the demand of the acidification phase.

[0061] It should be noted that the unit: mL / L / min represents the fluid volume per minute in the unit reactor volume (mL).

[0062] The unit: L / L / min represents the fluid volume per minute in the unit reactor volume (L).

[0063] Unit: L / L / d, which represents the fluid volume per day in unit reactor volume (L).

[0064] In order to further illustrate the present application, the following examples are provided to illustrate the anaerobic digestion method of distillation wastewater in straw ethanol production provided by the present application, but it should be understood that these examples are based on the technical scheme of the present application, and detailed implementation and specific operation process are given, which are only for further illustrating the features and advantages of the present application, but not for limiting the claims of the present application, and the protection scope of the present application is not limited to the following examples.

[0065] Example 1

[0066] The anaerobic digestion method of distillation wastewater in straw ethanol production of the present embodiment comprises the following steps:

[0067] Step S1: The distillation wastewater in straw ethanol production is sent into the acidification phase, and the acid production reaction is carried out under the condition of air being introduced and gas circulation in the acidification phase. The seed sludge of the acidification phase is organic wastewater anaerobic treatment granular sludge. The acid production reaction includes: the temperature of the acid production reaction is 35℃; the flow rate of the introduced air is 5 mL / L / min; the flow rate of the gas circulation in the acidification phase is 0.5 L / L / min; the stirring speed is 60 rpm; the liquid circulation amount is 50 L / L / d; the acidification treatment adopts the in-out feeding mode of day in and day out; the hydraulic retention time is 1 day; the oxidation-reduction potential of the liquid in the acidification phase is-300 mv; and the pH value of the liquid in the acidification phase is 5.

[0068] Step S2: The pretreated wastewater after the acid production reaction is precipitated and layered. The precipitation time of the pretreated wastewater is 60 min.

[0069] Step S3: The supernatant of the pretreated wastewater after the precipitation and layering is taken and sent into the methanogenesis phase to carry out the methanogenesis reaction. The seed sludge of the methanogenesis phase is organic wastewater anaerobic treatment granular sludge, and the liquid supply flow rate of the supernatant into the methanogenesis phase is 0.05 L / L / d.

[0070] Example 2

[0071] The anaerobic digestion method of distillation wastewater in straw ethanol production of the present embodiment comprises the following steps:

[0072] Step S1: The distillation wastewater in the straw ethanol preparation is sent into the acidification phase, and the acid production reaction is carried out under the condition of air input and gas circulation in the acidification phase. The seed sludge of the acidification phase is organic wastewater anaerobic treatment granular sludge. The acid production reaction includes: the temperature of the acid production reaction is 37℃; the flow rate of the air input is 10 mL / L / min; the flow rate of the gas circulation in the acidification phase is 1 L / L / min; the stirring speed is 80 rpm; the liquid circulation amount is 75 L / L / d; the acidification treatment adopts the day-in day-out feeding and discharging mode; the hydraulic retention time is 2 days; the oxidation-reduction potential of the liquid in the acidification phase is -250 mv; and the pH value of the liquid in the acidification phase is 7.

[0073] Step S2: The pretreated wastewater after the acid production reaction is precipitated and layered. The precipitation time of the pretreated wastewater is 80 min.

[0074] Step S3: The supernatant of the pretreated wastewater after the precipitation and the layering is taken and sent into the methane production phase to carry out the methane production reaction. The seed sludge of the methane production phase is organic wastewater anaerobic treatment granular sludge, and the liquid supply flow rate of the supernatant into the methane production phase is 0.08 L / L / d.

[0075] Example 3

[0076] The anaerobic digestion method of the distillation wastewater in the straw ethanol preparation of the present embodiment includes the following steps:

[0077] Step S1: The distillation wastewater in the straw ethanol preparation is sent into the acidification phase, and the acid production reaction is carried out under the condition of air input and gas circulation in the acidification phase. The seed sludge of the acidification phase is organic wastewater anaerobic treatment granular sludge. The acid production reaction includes: the temperature of the acid production reaction is 37℃; the flow rate of the air input is 10 mL / L / min; the flow rate of the gas circulation in the acidification phase is 1 L / L / min; the stirring speed is 80 rpm; the liquid circulation amount is 75 L / L / d; the acidification treatment adopts the day-in day-out feeding and discharging mode; the hydraulic retention time is 2 days; the oxidation-reduction potential of the liquid in the acidification phase is -250 mv; and the pH value of the liquid in the acidification phase is 7.

[0078] Step S2: The pretreated wastewater after the acid production reaction is precipitated and layered. The precipitation time of the pretreated wastewater is 80 min.

[0079] Step S3: The supernatant of the pretreated wastewater after the precipitation and the layering is taken and sent into the methane production phase to carry out the methane production reaction. The seed sludge of the methane production phase is organic wastewater anaerobic treatment granular sludge, and the liquid supply flow rate of the supernatant into the methane production phase is 0.08 L / L / d.

[0080] Test Example

[0081] (1) Composition of wastewater

[0082] Wastewater 1: Artificial wastewater was prepared with glucose as the source of chemical oxygen demand (COD) and Na2SO4 as the source of sulfate, and the composition was: COD 2000 mg / L, SO4 2- 300 mg / L.

[0083] Wastewater 2: Artificial wastewater was prepared with glucose as the source of chemical oxygen demand (COD) and Na2SO4 as the source of sulfate, and the composition was: COD 2000 mg / L, SO4 2- 1800 mg / L.

[0084] NH4Cl and KH2PO4 were added to wastewater 1 and wastewater 2 as nitrogen and phosphorus sources (the ratio of COD:N:P was 300:5:1), respectively, and 1 ml of trace element solution (mg / L) was added to each liter of wastewater: MgCl2·6H2O (100), CaCl2·2H2O (80), FeCl3·6H2O (60), CoCl2·6H2O (0.05), MnCl2·4H2O (0.05), ZnCl2 (0.05), AlCl3·6H2O (0.05), NiCl2·6H2O (0.05), H3BO3 (0.05), CuCl2·2H2O (0.05). The pH of wastewater 1 and wastewater 2 was maintained at 7.0±0.1.

[0085] (2) Seed sludge

[0086] Both the acidification phase and the methanogenic phase used organic wastewater anaerobic treatment granular sludge obtained from a starch wastewater treatment IC reactor as seed sludge.

[0087] The seed sludge of the acidification phase and the methanogenic phase contained: 11.3 g / L of mixed liquor suspended solids (SS) and 9.1 g / L of mixed liquor volatile suspended solids (VSS).

[0088] (3) Experimental procedure

[0089] The acidification phase reaction used a complete stirring type (CSTR) reactor (total volume and effective volume were 1.0 L and 0.8 L, respectively). The methanogenic phase used an IC reactor or a UASB reactor (total volume and effective volume were 1.0 L and 0.8 L, respectively).

[0090] The complete stirring type (CSTR) reactor was used in the acidification phase, and the IC reactor or UASB reactor combination was used as the two-phase reactor in the acidification phase. The complete stirring type (CSTR) reactor was used as a single reactor for anaerobic digestion reaction in the acidification phase. In the complete stirring type (CSTR) reactor, the gas from the acidification phase was pumped into the water bottle by a gas circulation pump (1.0 L / L / min), and the water-washed gas was returned to the reactor for the next cycle. At the same time of gas circulation, a small amount of air (10 ml / L / min) was supplied to the gas path. The reactor temperature was maintained at 37 °C, the stirring speed was 80 rpm, the hydraulic retention time was 2 days, the liquid circulation rate was 90 L / L / d, and the liquid oxidation-reduction potential was -250 mv.

[0091] The distillation wastewater treated by the complete stirring type (CSTR) reactor was precipitated for 80 min, and the supernatant was supplied to the IC reactor or UASB reactor at a liquid supply rate of 0.1 L / L / d for methanogenesis reaction, which generally lasted for 10 days.

[0092] The single-phase reactor and two-phase reactor experiments were divided into three stages. In the first stage, wastewater 1 was supplied; in the second stage, wastewater 2 was supplied; and in the third stage, wastewater 2 was supplied without gas circulation and micro-aeration in the acidification phase. The reactor was operated in a day-in and day-out mode, the acidification phase had a residence time of 2 days, and the methanogenesis phase had a residence time of 10 days. Each of the three stages was maintained for 30 days.

[0093] (4) Experimental results:

[0094] In the first stage, wastewater 1 was supplied into the single-phase reactor and the two-phase reactor, respectively. The COD removal rates of the single-phase and two-phase reactors were 93.7% and 93.5%, respectively, and the methane production rates were 311 ml / g-COD and 307 ml / g-COD, respectively.

[0095] It can be seen that, due to the low content of SO2 - in the wastewater, the H2S generated by its reduction did not significantly inhibit the single-phase or two-phase reactor, and both configurations showed good performance, with similar COD removal rates and methane production rates.

[0096] In the second stage, wastewater 2 replaced wastewater 1 and was supplied into the single-phase and two-phase reactors. The organic degradation in the single-phase reactor was significantly inhibited, and the COD removal rate decreased to about 80% after 30 days of operation, and the methanogenesis efficiency decreased to about 130 ml / g-COD. However, the two-phase reactor showed no significant change, with a COD removal efficiency of ≥90% (90-92%) and a methane production rate of ≥300 ml / g-COD (300-315 ml / g-COD).

[0097] This is because, in the anaerobic digestion process of the single-phase reactor, the high concentration of SO2 -Reduction to H2S, which is toxic to methanogens and even acidogens, causes COD production and methane production efficiency to decrease. In the two-phase reactor, because SO2 - Reduction to H2S in the acidification reactor, and reaction of H2S with supplied O2 to produce elemental S and part of SO2 - , which precipitates in the acidification sludge or on the upper cover of the reactor, and only low-sulfur acidification liquid (SO2 - concentration of about 438 mg / L) enters the methanogenic phase, and there is no inhibition of anaerobic digestion, especially of methanogens, by H2S.

[0098] The third stage: wastewater 2 is continuously supplied to the single-phase and two-phase reactors, and the degradation of organic matter in the single-phase reactor is significantly inhibited and continuously decreases, and after 30 days of operation, the COD removal rate decreases to 60%, and the methane production efficiency decreases to about 30 ml / g-COD, and the reactor is on the verge of collapse; and the performance of the two-phase reactor also deteriorates, for example, its COD removal efficiency decreases to about 75%, and the methane production rate is about 210 ml / g-COD. This shows that SO2 - is reduced to H2S, and excessive H2S causes severe inhibition of acidification microorganisms, thereby hindering the sulfate reduction process (compared with the second stage, SO4 2- is higher, about 1200 mg / L), and the sulfur-containing acidification liquid enters the methanogenic phase to further reduce H2S, causing inhibition of acidification bacteria and methanogens, and the methane production rate decreases; but because the two-phase reactor can provide a separate favorable environment to alleviate the inhibition of methanogens compared with the single-phase reactor.

[0099] Examples

[0100] Taking the distillation wastewater in straw ethanol production as an example, the COD concentration of the wastewater is 6290 mg / L, and the SO4 2- concentration is 2300 mg / L. The wastewater is treated by anaerobic digestion using the two-phase configuration reactor (coupled with micro-aeration + gas circulation system) in the test example, and the reactor is stably operated for 90 days, during which the COD removal efficiency fluctuates in the range of about 90-92.7%, and the stable methane production rate is 301 ml / g-COD.

[0101] The above specific embodiments further illustrate the purpose, technical solutions, and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for anaerobic digestion of distillation wastewater in the production of straw ethanol, characterized by, The anaerobic digestion method includes: The distillation wastewater in the straw ethanol production is sent to the acidification phase, and the acid production reaction is carried out under the condition of passing in trace amount of air and gas circulation in the acidification phase; The pretreated wastewater after the acid production reaction is subjected to sedimentation and layering; The supernatant of the pretreated wastewater after the sedimentation and layering is taken and sent to the methanogenesis phase to carry out the methanogenesis reaction; The temperature for carrying out the acid production reaction is 35℃-37℃ or 53℃-55℃; In the anaerobic digestion method, the judgment for stopping the air passing in is: When the oxidation-reduction potential of the liquid in the acidification phase is greater than or equal to -200 mv; And / or, when the oxygen content in the produced gas of the acidification phase is greater than or equal to 1%; In the acid production reaction: The flow rate of the air passing in is 5 mL / L / min-15 mL / L / min; The flow rate of the gas circulation in the acidification phase is 0.5 L / L / min-4 L / L / min; The stirring speed is 60 rpm-100 rpm; The liquid circulation amount is 50 L / L / d-100 L / L / d; The oxidation-reduction potential of the liquid in the acidification phase is -300 mv--200 mv.

2. The method of claim 1, wherein the anaerobic digestion of the distillation wastewater is performed at a temperature of 30 to 60°C. The seed sludge of the acidification phase is the organic wastewater anaerobic treatment granular sludge.

3. The method of claim 1, wherein the anaerobic digestion of the distillation wastewater is performed at a temperature of 30 to 60°C. The acid production reaction includes: The acidification treatment adopts the day-in day-out feeding and discharging mode; And / or, the hydraulic retention time is 1 day-4 days.

4. The method of claim 1, wherein the anaerobic digestion of the distillation wastewater is performed at a temperature of 30 to 60°C. The acid production reaction further includes: The pH value of the liquid in the acidification phase is 5-12.

5. The method of claim 1, wherein the anaerobic digestion of the distillation wastewater is performed at a temperature of 30 to 60°C. The sedimentation time of the pretreated wastewater is 60 min-120 min.

6. The method of claim 1, wherein the anaerobic digestion of the distillation wastewater is performed at a temperature of 30 to 60°C. The seed sludge of the methanogenesis phase is the organic wastewater anaerobic treatment granular sludge.

7. The method of claim 1, wherein the anaerobic digestion of the distillation wastewater is performed at a temperature of 30 to 60°C. The liquid supply flow rate of the supernatant into the methanogenesis phase is 0.05 L / L / d-0.1 L / L / d.

8. The method of claim 1, wherein the anaerobic digestion of the distillation wastewater is performed at a temperature of 30 to 60°C. The anaerobic digestion method further includes: the lower sludge after the sedimentation and layering treatment is returned to the acidification phase.

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