CN107287247A - Upflow anaerobic sludge blanket process connected with microorganism electrolysis cell ladder using excess sludge produce hydrogen method - Google Patents

Abstract

The invention discloses a method for producing hydrogen from excess sludge in series with an upflow anaerobic sludge bed and a microbial electrolytic cell. The remaining sludge was used as the substrate, and the UASB reactor was started; the surplus sludge of the sewage plant was used as the inoculum, and the double-chamber MFC was used to enrich the anode electrogenic bacteria; anode; feed the excess sludge into the activated UASB reactor, make it fully contact with the fermentation microorganisms in each layer of granular sludge in the reaction zone, and carry out anaerobic fermentation acid production reaction; the remaining sludge after the above fermentation acid production The sludge is transferred to a microbial electrolysis cell (MEC) for hydrogen production at room temperature. The invention realizes the stabilization and resource utilization of excess sludge by combining the two technologies, and solves the problems of low energy recovery efficiency and low utilization rate of organic matter in the anaerobic digestion technology.

Description

Up-flow anaerobic sludge bed and microbial electrolytic cell cascade utilization of excess sludge production hydrogen method

technical field

The invention relates to a method for producing hydrogen by utilizing excess sludge, in particular to a method for producing hydrogen by utilizing excess sludge in series with an upflow anaerobic sludge bed and a microbial electrolytic cell.

Background technique

Excess sludge is a by-product of sewage treatment, with a moisture content of about 98%-99%, containing sediment, fibers, colloids, organic matter, microorganisms and metal elements. The organic matter in the sludge not only has a high concentration and is not easy to degrade, but also contains more pathogenic microorganisms, which will pollute the water body and soil. Therefore, the stabilization of excess sludge is the main goal of sludge treatment.

At present, the commonly used method for stabilizing excess sludge is anaerobic digestion, but anaerobic digestion has disadvantages such as long start-up time, slow reaction speed, and large floor area. Hydrogen is a clean energy due to its high calorific value and carbon neutrality. The use of excess sludge to produce hydrogen or methane is of great significance for the stabilization and resource utilization of excess sludge. However, anaerobic fermentation produces good results only under medium or high temperature environmental conditions. In the actual operation and maintenance process, maintaining medium or high temperature increases the cost of hydrogen production.

In order to improve the performance of sludge anaerobic digestion, break through the thermodynamic barrier, increase the efficiency of hydrogen production, and reduce the cost of hydrogen production, it is necessary to improve the traditional sludge anaerobic digestion process.

Contents of the invention

In order to solve the deficiencies of the prior art, the object of the present invention is to provide a method for producing hydrogen by utilizing excess sludge in series with an upflow anaerobic sludge bed and a microbial electrolytic cell.

In order to achieve the above object, the present invention adopts the following technical solutions:

The method for producing hydrogen from excess sludge by cascading an upflow anaerobic sludge bed and a microbial electrolytic cell in series, comprises the following steps:

S1. Use the anaerobic sludge of other anaerobic reactors as the inoculated sludge, and use the remaining sludge of the sewage plant as the substrate to start the UASB reactor;

S2. Using the remaining sludge from the sewage plant as the inoculum, use the double-chamber MFC to enrich the anode electrogenic bacteria; transfer the anode enriched electrogenic bacteria to MEC as the anode of the MEC reactor;

S3. Feed the excess sludge into the reaction zone of the activated UASB reactor, make the excess sludge fully contact with the fermentation microorganisms in the granular sludge of each layer in the reaction zone, and perform anaerobic fermentation acid production reaction;

S4. Transfer the remaining sludge after acid production by fermentation to a microbial electrolysis cell (MEC) for hydrogen production at room temperature.

The process of starting the UASB reactor in the above step S1 is:

The nutrient solution prepared with glucose, nitrogen, phosphorus and trace elements is used as the matrix, and the anaerobic sludge in other anaerobic reactors is used as the seed sludge; gradually increase the proportion of excess sludge in the matrix until the matrix becomes surplus Sludge, to complete the domestication of anaerobic microorganisms in granular sludge.

The process of enriching anodic electrogenic bacteria by using the double-chamber MFC in the above step S2 is:

A1. Mix the inoculum with a concentration of 3.1-6.4g/L and solution A to obtain solution B;

A2. Add solution B to the anode chamber of the dual-chamber MFC, and add solution C to the cathode chamber of the dual-chamber MFC; start the MFC at a room temperature of 20-25°C, and when the voltage value of the MFC tends to be stable, replace solution B and solution C to complete a operating cycle;

A3. Repeat the above steps to complete 3 operation cycles to complete the enrichment of anodic electrogenic bacteria.

The operating parameters of the UASB reactor in the above step S3 are: reaction temperature 35°C, pH value 5, organic load 2-5kgCOD/m ³ ·d, HRT 26h, SRT 8d, ORP-300-200mV, The material C/N is 160-250.

Temperature has a great influence on the growth and metabolic rate of anaerobic microorganisms. Generally speaking, the best working temperature for acid-producing bacteria is 35°C. When the temperature is lower than 25°C, the rate of acid production is relatively low. The rate will be reduced by more than 50%; the adaptation range of the hydrolytic fermentation bacteria and the hydrogen-producing acetogenic bacteria to pH is roughly 5-6.5. The pH value can also affect the type of acid produced by fermentation. Under normal anaerobic conditions (ORP is in the range of -150 ~ -400mV),

When the pH value is between 4.0 and 4.5, it is mainly ethanol fermentation;

When the pH value is between 4.5 and 5.0, it is mainly butyric acid type fermentation, and may also be accompanied by ethanol type fermentation;

When the pH value is around 5.0, it is mixed fermentation;

When the pH value is around 5.5, it is propionic acid fermentation;

When the pH value is above 6.0, it is mainly butyric acid fermentation;

When the HRT was about 30h, the specific yields of VFAs and SCOD in the UASB reactor reached the maximum value, and continued to increase the HRT, and the yields of VFAs and SCOD decreased due to the decrease of VSS;

When SRT<8d, the reactor mainly showed the characteristic of acidification, and when SRT>8d, the reactor showed the characteristic of producing methane;

ORP affects the type of fermentation and the activity of acid-producing bacteria to a certain extent. It is generally believed that -200~-300mV is the best ORP range for acid-producing bacteria.

When the ORP is -400～-200mV, the fermentation of ethanol and butyric acid is the main type.

When the ORP is -250～+100mV, the anaerobic fermentation is mainly in the form of propionic acid;

When the C/N increased to 156-256, the growth rate of VFAs, H2 and CO2 increased rapidly, and at the same time, different types of fermentation acid production could be realized by controlling the initial C/N,

When the initial C/N is between 12 and 44, the acetic acid fermentation type is formed.

When the initial C/N is between 56 and 69, the type of propionic acid fermentation can be realized,

And when the C/N is between 156 and 256, butyric acid fermentation is formed;

The process of producing hydrogen at room temperature in the microbial electrolytic cell in the above step S4 is:

B1. Add in sequence to the single-chamber MEC reactor: mixed solution D, trace element solution E and vitamin solution F;

B2. Connect a resistor in series between the two poles of the MEC, apply an external voltage of 0.8V, on the basis of this voltage, add 50mmol/L exogenous trehalose to optimize the MEC, and use the remaining sludge (sludge digestate) after acid production by fermentation as The substrate completes hydrogen production at room temperature.

The MEC anode microorganisms oxidize the dissolved substrates in the remaining sludge to produce hydrogen ions and electrons. The generated electrons are transmitted to the anode of the MEC through the mediator or the respiratory chain of the microorganism itself, and then transmitted to the cathode of the MEC by the external circuit through the wire. , the hydrogen ions pass through the proton exchange membrane or directly to the cathode. Under the action of a lower voltage power supply, the hydrogen ions in the cathode chamber accept electrons and generate hydrogen gas in the anode chamber. Taking glucose as an example, the reaction equation is as follows:

anode:

cathode:

Overall response:

The role of solutions E and F is to provide trace elements needed for microbial growth.

Further, in the above step S2, the anodes are all graphite fiber brush electrodes, and the cathode is a non-waterproof carbon cloth electrode; before use, the graphite fiber brush electrode and the carbon cloth electrode are ultrasonically cleaned in acetone, ethanol and pure water for 10 minutes, and then in High temperature treatment at 450°C for 30 minutes.

Further, the volume ratio of the inoculum to the solution A in the above step A1 is 1:2.

Further, the composition of solution A in step A1 is as follows: 1.5 g of NaAc, 2.4145 g of KH2PO4, 7.3539 g of K2HPO4.3H2O, 0.31 g of NH4Cl, and 0.13 g of KCl per liter of deionized water;

The composition of solution C is that per liter of deionized water contains: KH2PO4 2.4145g, K2HPO4·3H2O 7.3539g, NH4Cl 0.31g, KCl 0.13g.

Further, the composition of trace element solution E in step B1 includes: 1.5g of triacetic acid, 3.0g of MgSO4 7H2O, 0.5g of MnSO4 2H2O, 1.0g of NaCl, 0.1g of FeSO4 7H2O, 0.1g of CoCl2 per liter of deionized water , CaCl2 2H2O 0.1g, ZnSO4 0.1g, CuSO4 5H2O 0.01g, AlK(SO4)2 0.01g, H3BO3 0.01g, Na2MoO4 0.025g, NiCl 6H2O 0.024g;

The vitamin solution F component contains per liter of deionized water: biotin 2mg, folic acid 2mg, vitamin B6 10mg, vitamin B1 5mg, vitamin B2 5mg, niacin 5mg, calcium pantothenate 5mg, vitamin B12 0.1mg, 4-aminobenzoic acid 5mg , lipoic acid 5mg.

The benefits of the present invention are:

This method proposes a method of using an upflow anaerobic sludge bed and a microbial electrolytic cell in series to produce hydrogen from excess sludge, and controls the anaerobic digestion of excess sludge in the stage of fermentation and acid production, so that the final product of fermentation acid , such as VFAs, alcohols, polysaccharides, amino acids, etc., as the substrates of MEC to achieve hydrogen production at room temperature.

MEC can use various organic matter in excess sludge to produce hydrogen at room temperature, and the range of substrates that MEC can use is very wide, from VFAs, polysaccharides and proteins to cellulose can be used as carbon sources for MEC.

Compared with the prior art, the present invention provides an upflow anaerobic sludge bed and microbial electrolytic cell cascaded method for hydrogen production from excess sludge. By placing MEC at the back end of the anaerobic digestion reactor, the two Or form an enhanced hydrogen production system that can use various organic substances in excess sludge step by step;

Through the cascade utilization of sludge organic matter, the efficiency of hydrogen production from excess sludge is maximized. The organic matter in the sludge is either difficult to be directly used by MEC, or the efficiency of MEC to degrade sludge is not high because of the slow hydrolysis rate of sludge.

For this reason, the scheme of the present invention adopts the combination technology of anaerobic fermentation acid production and microbial electrolysis cell. It is easy to be utilized by the microbial electrolytic cell, and the remaining sludge after acidogenic fermentation can still be continuously utilized by the microbial electrolytic cell. Therefore, the combination of the two technologies not only increases the degradation rate of sludge organic matter, but also improves the hydrogen production efficiency of the microbial electrolytic cell;

The graphite fiber brush electrode and the carbon cloth electrode were treated at 450°C for 30 minutes to increase the roughness and surface area of the electrode surface, which is beneficial to the adhesion of anode electrogenic bacteria and the coating of cathode catalyst.

The method successfully realizes the stabilization, reduction and resource utilization of excess sludge in urban sewage plants, and has strong practicability and wide applicability.

detailed description

The present invention will be specifically introduced below in conjunction with specific embodiments.

A method for producing hydrogen from excess sludge in series with an upflow anaerobic sludge bed and a microbial electrolytic cell, comprising the following steps:

Step 1, start the UASB reactor with anaerobic sludge from other anaerobic reactors as inoculation sludge;

The start-up process is as follows: first, use the nutrient solution prepared by glucose, nitrogen, phosphorus and trace elements as the substrate, and use the anaerobic sludge in other anaerobic reactors as the inoculum; gradually increase the proportion of the remaining sludge in the culture medium, The acclimatization of anaerobic microorganisms in the granular sludge is completed until the substrate is completely turned into excess sludge.

Step 2, enriching anodic electrogenic bacteria by using double-chamber MFC;

The enrichment process is as follows: the excess sludge (inoculum) with a concentration of 3.1-6.4g/L is mixed with solution A at a volume ratio of 1:2 to obtain solution B, solution B is added to the double-chamber MFC anode chamber, and solution C is added to Two-chamber MFC cathode chamber; start the MFC at room temperature of 20-25°C, and when the voltage value of the MFC tends to be stable, replace solution B and solution C to complete an operation cycle.

The MFC voltage value of the MFC is stabilized for 3 times, that is, 3 operating cycles, and then the enrichment of anodic electrogenic bacteria is completed.

This anode was transferred to the MEC as the anode of the MEC reactor.

Here, the remaining sludge is used as an inoculum for directional screening and enrichment of electrogenic bacteria; solution A provides the substrate for the enrichment culture stage; solution C is a buffer solution. Electrogenic bacteria use organic matter to maintain growth in an anaerobic environment, and oxidize organic matter to transfer the generated electrons to the electrode, with the electrode as the final electron acceptor. A biofilm is formed on the anode and electrons are transferred to the anode through the conductivity of the membrane. The biofilm has rich microbial diversity and complex microbial phase, and a variety of microorganisms are enriched and grown on the membrane. However, the bacteria that dominate the surface of the MFC anode biofilm are not necessarily all electricity-producing bacteria, and relatively many of them are some fermenting bacteria and acid-producing bacteria. suitable substrate.

Step 3, using the excess sludge as a substrate to operate the UASB reactor;

The operating parameters are: reactor temperature 35°C, reactor pH=5, organic load 2-5kgCOD/m ³ d, HRT 26h, SRT 8d, ORP -300-200mV, feed C/N 160 ~250.

The remaining sludge is controlled in the stage of fermentation and acid production, and the remaining sludge enters the reaction zone from the inlet at the bottom of the UASB reactor started in step 1, so that the substrate and the fermentation microorganisms in each layer of granular sludge in the reaction zone are fully contacted, anaerobic reaction.

The anaerobic digestion of excess sludge is controlled as butyric acid fermentation, and the fermentation products are mainly butyric acid, propionic acid, and ethanol. These fermentation products and the excess sludge after fermentation can be used as the substrate of the MEC reactor and are The utilization of electrogenic bacteria.

Step 4, transferring the product after acid production by fermentation to a microbial electrolytic cell for hydrogen production at room temperature;

The process of hydrogen production is as follows: the anode of the MEC reactor is the MFC anode in step 2, and the cathode of the MEC reactor is platinum-loaded carbon cloth; the mixed solution D, trace element solution E and vitamin solution F are sequentially added to the single-chamber MEC reactor; A resistor is connected in series between the poles of the MEC, and an external voltage of 0.8V is applied.

The MEC anode microorganisms oxidize the dissolved substrates in the remaining sludge to produce hydrogen ions and electrons. The generated electrons are transmitted to the anode of the MEC through the mediator or the respiratory chain of the microorganism itself, and then transmitted to the cathode of the MEC by the external circuit through the wire. , the hydrogen ions pass through the proton exchange membrane or directly to the cathode. Under the action of a lower voltage power supply, the hydrogen ions in the cathode chamber accept electrons and generate hydrogen gas in the anode chamber.

Taking glucose as an example, the reaction equation is as follows:

anode:

cathode:

Overall response:

The role of solutions E and F is to provide trace elements needed for microbial growth.

Among them, the anodes of steps 2 and 4 are graphite fiber brushes, and the cathodes are carbon cloths; before use, graphite fiber brushes and carbon cloths are ultrasonically cleaned in acetone, ethanol and pure water for 10 minutes, and then treated at 450 ° C for 30 minutes .

The components of solution A are: NaAc 1.5g, KH ₂ PO ₄ 2.4145g, K ₂ HPO ₄ 3H ₂ O7.3539g, NH ₄ Cl 0.31g, KCl 0.13g per liter of deionized water; Deionized water contains: KH ₂ PO ₄ 2.4145g, K ₂ HPO ₄ ·3H ₂ O 7.3539g, NH ₄ Cl 0.31g, KCl 0.13g;

The composition of trace element solution E is per liter of deionized water: 1.5g triacetic acid, 3.0g MgSO ₄ 7H ₂ O, 0.5g MnSO ₄ 2H ₂ O, 1.0g NaCl, 0.1g FeSO ₄ 7H ₂ O, CoCl ₂ 0.1g, CaCl ₂ 2H ₂ O 0.1g, ZnSO ₄ 0.1g, CuSO ₄ 5H ₂ O 0.01g, AlK(SO ₄ ) ₂ 0.01g, H ₃ BO ₃ 0.01g, Na ₂ MoO ₄ 0.025g, NiCl 6H ₂ O 0.024g;

The vitamin solution F component contains per liter of deionized water: biotin 2mg, folic acid 2mg, vitamin B ₆ 10mg, vitamin B ₁ 5mg, vitamin B ₂ 5mg, niacin 5mg, calcium pantothenate 5mg, vitamin B ₁₂ 0.1mg, 4- Aminobenzoic acid 5mg, lipoic acid 5mg.

Example:

An example of hydrogen production from excess sludge using an upflow anaerobic sludge bed and a microbial electrolytic cell in series:

SS 7.51g/L, VSS 5.16g/L, TCOD 8774mg/L, SCOD 46mg/L, protein 3mg/L, total sugar 4mg/L, nucleic acid 4mg/L, ammonia nitrogen 81mg/L in the residual sludge of a sewage treatment plant .

In UASB, the constant temperature is 35°C, the pH of the reactor is controlled to be 5, the organic load is 2-5kgCOD/m3·d, the HRT is 26h, the SRT is 8d, the ORP is -300-200mV, and the C/N is 160-250.

The utilization rate of protein in the remaining sludge after fermentation and acid production is 54.93%, the utilization rate of total sugar is 39.11%, the time for the total VFAs to reach the maximum is 3 days, the maximum amount is 1383.05mgCOD/L, and the acid production rate is 197.55 mgCOD/gVSS.

Connect a resistor in series between the two poles of the MEC, apply an external voltage of 0.8V, control the temperature at 4-9°C on the basis of this voltage, and add 50mmol/L of exogenous trehalose to optimize the utilization of the remaining sludge after fermentation and acid production by MEC The hydrogen production is completed for the substrate at room temperature operation efficiency, the SCOD removal efficiency is 40.45%, the hydrogen production rate is 0.084gH ₂ /gSCOD, the coulombic efficiency is 56.46%, the hydrogen volume is 75.37mL, and the hydrogen production rate is 0.45m ³ /m ³ reactor/d, Energy efficiency 211.01%.

The order of utilization of organic matter was acetic acid>protein>propionic acid>butyric acid>valeric acid>polysaccharide.

Therefore, placing the MEC at the back end of the anaerobic digestion reactor, so that the two form an enhanced hydrogen production system that can utilize various organic matter in steps, has positive significance for the further utilization and further conversion of fermentation products.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the above-mentioned embodiments do not limit the present invention in any form, and all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (9)

1. The method for producing hydrogen from excess sludge in series with an upflow anaerobic sludge bed and a microbial electrolytic cell, is characterized in that it comprises the following steps: S1. Use the anaerobic sludge of other anaerobic reactors as the inoculated sludge, and use the remaining sludge of the sewage plant as the substrate to start the UASB reactor; S2. Using the remaining sludge from the sewage plant as the inoculum, use the double-chamber MFC to enrich the anode electrogenic bacteria; transfer the anode enriched electrogenic bacteria to MEC as the anode of the MEC reactor; S3. Feeding the remaining sludge into the activated UASB reactor, making it fully contact with the fermentation microorganisms in the granular sludge of each layer in the reaction zone, and performing anaerobic fermentation acid production reaction; S4. Transfer the remaining sludge after acid production by fermentation to a microbial electrolysis cell (MEC) for hydrogen production at room temperature. 2. The method according to claim 1, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, wherein the process of starting the UASB reactor in the step S1 is: The nutrient solution prepared with glucose, nitrogen, phosphorus and trace elements is used as the matrix, and the anaerobic sludge in other anaerobic reactors is used as the seed sludge; gradually increase the proportion of excess sludge in the matrix until the matrix becomes surplus Sludge, to complete the domestication of anaerobic microorganisms in granular sludge. 3. The method according to claim 1, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, characterized in that, in the step S2, the use of double-chamber MFC to enrich the anode produces hydrogen. The process of electrobacteria is: A1. Mix the inoculum with a concentration of 3.1-6.4g/L and solution A to obtain solution B; A2. Add solution B to the anode chamber of the dual-chamber MFC, and add solution C to the cathode chamber of the dual-chamber MFC; start the MFC at a room temperature of 20-25°C, and when the voltage value of the MFC tends to be stable, replace solution B and solution C to complete a operating cycle; A3. Repeat the above steps to complete 3 operation cycles to complete the enrichment of anodic electrogenic bacteria. 4. The method according to claim 1, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, characterized in that, the operating parameters of the UASB reactor in the step S3 are: reaction The temperature is 35°C, the pH value is 5, the organic load is 2-5kgCOD/m ³ ·d, the HRT is 26h, the SRT is 8d, the ORP-300-200mV, and the feed C/N is 160-250. 5. The method according to claim 1, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, characterized in that, in the step S4, the normal temperature hydrogen production process of the microbial electrolytic cell is as follows: : B1. Add in sequence to the single-chamber MEC reactor: mixed solution D, trace element solution E and vitamin solution F; B2. Connect a resistor in series between the poles of the MEC and apply an external voltage of 0.8V. On the basis of this voltage, add 50mmol/L of exogenous trehalose to optimize the MEC, and use the remaining sludge after fermentation to produce acid as the substrate to operate at room temperature. Hydrogen at room temperature. 6. The method according to claim 1, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, wherein, in the step S2, the anodes are all graphite fiber brushes, and the cathodes are graphite fiber brushes. Carbon cloth: Before use, the graphite fiber brush and carbon cloth were ultrasonically cleaned in acetone, ethanol and pure water for 10 minutes, and then treated at 450°C for 30 minutes. 7. The method according to claim 3, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, wherein the volume ratio of the inoculum to the solution A in the step A1 is 1:2. 8. The method according to claim 3, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, wherein the composition of solution A in the step A1 is deionized per liter Contains in water: NaAc 1.5g, KH ₂ PO ₄ 2.4145g, K ₂ HPO ₄ 3H ₂ O 7.3539g, NH ₄ Cl 0.31g, KCl 0.13g; The composition of solution C is that per liter of deionized water contains: KH ₂ PO ₄ 2.4145g, K ₂ HPO ₄ ·3H ₂ O 7.3539g, NH ₄ Cl 0.31g, KCl 0.13g. 9. The method according to claim 5, wherein the upflow anaerobic sludge bed and the microbial electrolytic cell are connected in series to utilize excess sludge to produce hydrogen, characterized in that, the trace element solution E component in the step B1 is de Deionized water contains: triacetic acid 1.5g, MgSO ₄ • 7H ₂ O 3.0g, MnSO ₄ • 2H ₂ O 0.5g, NaCl 1.0g, FeSO ₄ • 7H ₂ O 0.1g, CoCl ₂ 0.1g, CaCl ₂ • 2H ₂ O 0.1g, ZnSO ₄ 0.1g, CuSO ₄ 5H ₂ O 0.01g, AlK(SO ₄ ) ₂ 0.01g, H ₃ BO ₃ 0.01g, Na ₂ MoO ₄ 0.025g, NiCl 6H ₂ O 0.024g; Vitamin solution F contains per liter of deionized water: biotin 2mg, folic acid 2mg, vitamin B6 10mg, vitamin B1 5mg, vitamin B2 5mg, niacin 5mg, calcium pantothenate 5mg, vitamin B12 0.1mg, 4-aminobenzoic acid 5mg , lipoic acid 5mg.