Method for producing hydrogen and recycling phosphorus through electrolysis of neutral Fenton regulated residual sludge microorganism

A technology of microbial electrolysis and excess sludge

Inactive Publication Date: 2018-11-06

HUAZHONG UNIV OF SCI & TECH

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AI-Extracted Technical Summary

Problems solved by technology

[0004] In view of the above defects or improvement needs of the prior art, the object of the present invention is to provide a method for reclaiming phosphorus by microbial electrolysis of neutral Fenton conditioning residual sludge, wherein through the overall process design of the treatment method, and each Key process steps (such as neutral Fenton conditioning, anaerobic digestion pretreatment, etc.) are improved and further optimized. Compared with the prior art, the problems of residual sludge treatment difficulty, poor effect and high cost can be effectively solved. The present invention utilizes The coordinated treatment of neutral Fenton conditioning, anaerobic digestion...

Method used

Be applicable to the chelating agent of the present invention except the 10mM nitrilotriacetic acid solution or the 10mM protocatechuic acid solution used in the above-mentioned embodiment, also can adopt the chelating agent of other concentrations, as long as these chelating agents can make neutral Fenton conditioning should continue. For the specific kind of buffer, the present invention can adopt conventional buffer, such as phosphate buffer, but because the present invention will reclaim ...

Abstract

The invention discloses a method for producing hydrogen and recycling phosphorus through electrolysis of neutral Fenton regulated residual sludge microorganism. The method comprises the following steps: firstly, performing neutral Fenton regulation on residual sludge, then performing anaerobic digestion on the regulated residual sludge, and controlling the anaerobic digestion process of the residual sludge, so as to obtain residual sludge supernatant at an acid production stage; then adding the residual sludge supernatant into an MEC reactor subjected to microbial acclimation, applying external micro voltage to the MEC reactor, and performing MEC hydrogen production; adding a magnesium source into catholyte of the MEC reactor after MEC hydrogen production is completed, adding the residualsludge supernatant at the anaerobic digestion methane production stage into the MEC reactor, and adjusting the pH value of a cathode chamber, so as to separate out struvite precipitate. Through improvement and further optimization to the technical process design of the whole treatment method and all key technical steps, compared with the prior art, the method has the advantages that the problems of high difficulty, poor effect and high cost in residual sludge treatment are solved, and phosphorus can be recycled in a struvite mode.

Application Domain

Sludge treatment by oxidationSpecific water treatment objectives +3

Technology Topic

ChemistryPre treatment +10

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Examples

Experimental program(4)

Example Embodiment

[0039] Example 1

[0040] (I) Neutral Fenton conditioning: Take 500 mL of excess sludge with a TS content of 4.5 g/L and place it in a beaker, add 3.75 mL of 10 mM FeCl 3 Immediately after the solution, add 5.6mL of 10mM protocatechuic acid solution (of course, other concentrations of protocatechuic acid solution can also be used), stir quickly for 30s, and then add 0.4mL of 30% H 2 O 2 , stir quickly for 30s, and then stir slowly for 2h;

[0041] (II) Anaerobic digestion pretreatment: 400 mL of pretreated sludge in the step was added to 100 mL of anaerobic granular sludge to mix evenly, the fermentation concentration was 5%, the fermentation liquid was filled with high-purity nitrogen for 15 minutes, and anaerobic digestion was performed at 35°C 3d;

[0042] (III) MEC microbial acclimation: The total volume of the double-bottle MEC reactor is 600 mL and the effective volume is 500 mL. The anode of the MEC reactor is carbon brush, the cathode adopts stainless steel mesh, and the inoculum adopts the stable running MEC effluent. 1.5g/L sodium acetate is the carbon source, and a voltage of 0.6V is applied, and a 10Ω resistor is connected in series in the circuit at the same time. Start at room temperature of 25 °C, when the current cycle at both ends of the external resistor is stable for more than 3 cycles, it means that the domestication of anode microorganisms in the MEC is completed, and the MEC reactor is successfully started;

[0043] (IV) Hydrogen production by MEC: Mix 500 mL of excess sludge supernatant and buffer solution after anaerobic digestion pretreatment at a volume ratio of 1:1, fill with high-purity nitrogen for 15 minutes, then feed into the MEC reactor, and add 0.6 The V voltage continues to be maintained in the circuit while a 10Ω resistor is connected in series. After 3 days of digestion, when the COD degradation rate in the electrolyte solution in the MEC reactor reaches 80%, the MEC hydrogen production step can be considered to be completed;

[0044] (V) Struvite precipitation: After the completion of the MEC reaction for hydrogen production, 19 g MgCl was added to the catholyte 2 and 50mL NH 4 + The concentration of the supernatant in the methane-producing stage of anaerobic digestion was 4.8 g/L, the pH of the catholyte was adjusted to 8.5 with 1 mol/L NaOH solution, the magnetic stirring speed of the cathodic chamber was 100 rpm/min, and the reaction time was 120 min and then allowed to stand for 1 h. The precipitated struvite was collected, freeze-dried and stored.

Example Embodiment

[0045] Example 2

[0046] (I) Neutral Fenton conditioning: take 500 mL of excess sludge with a TS content of 5.7 g/L and place it in a beaker, add 10 mM FeCl 3 Immediately after 4.75 mL of the solution, add 7.1 mL of 10 mM nitrilotriacetic acid solution (of course, other concentrations of nitrilotriacetic acid solution can also be used), stir rapidly for 30 s, and then add 0.5 mL of 30% H 2 O 2 , stir quickly for 30s, and then stir slowly for 2h;

[0047] (II) Anaerobic digestion pretreatment: 400 mL of pretreated sludge in the step was added to 100 mL of anaerobic granular sludge to mix evenly, the fermentation concentration was 7%, the fermentation liquid was filled with high-purity nitrogen for 15 minutes, and anaerobic digestion was carried out at 35°C 3d;

[0048] (III) MEC microbial acclimation: The total volume of the double-bottle MEC reactor is 600 mL and the effective volume is 500 mL. The anode of the MEC reactor is carbon brush, the cathode adopts stainless steel mesh, and the inoculum adopts the MEC effluent of stable operation. 1g/L sodium acetate is the carbon source, and a voltage of 0.8V is applied, and a 100Ω resistor is connected in series in the circuit at the same time. Start at room temperature of 25°C, when the current cycle at both ends of the external resistor is stable for more than 3 cycles, it means that the domestication of anode microorganisms in the MEC is completed, and the MEC reactor is successfully started;

[0049] (IV) Hydrogen production by MEC: Mix 500 mL of excess sludge supernatant and buffer solution after anaerobic digestion pretreatment at a volume ratio of 1:1, fill with high-purity nitrogen for 15 minutes, then feed into the MEC reactor, and add 0.8 V voltage, a 100Ω resistor is connected in series in the circuit at the same time. After 3 days of digestion, when the COD degradation rate in the electrolyte solution in the MEC reactor reaches 80%, the MEC hydrogen production step can be considered to be completed;

[0050] (V) Struvite precipitation: After the completion of the MEC reaction for hydrogen production, 23.5 g of MgCl was added to the catholyte 2 and 75mLNH 4+The concentration of the supernatant in the methane-producing stage of anaerobic digestion was 4.8 g/L, the pH value of the cathode electrolyte was adjusted to 9 with 1 mol/L NaOH solution, the magnetic stirring speed of the cathode chamber was 200 rpm/min, and the reaction time was 120 min and then left to stand for 1 h. The precipitated struvite was collected, freeze-dried and stored.

Example Embodiment

[0051] Example 3

[0052] (I) Neutral Fenton conditioning: Take 500 mL of excess sludge with a TS content of 12.5 g/L and place it in a beaker, add 10 mM FeCl 3 Immediately after 21 mL of the solution, 32.5 mL of 10 mM protocatechuic acid solution was added, stirred rapidly for 60 s, and then 2.4 mL of 30% H was added. 2 O 2 , stir quickly for 30s, and then stir slowly for 2h;

[0053] (II) Anaerobic digestion pretreatment: add 350 mL of pretreated sludge in the step to 150 mL of anaerobic granular sludge and mix evenly, the fermentation concentration is 9%, the fermentation liquid is filled with high-purity nitrogen for 30 minutes, and anaerobic digestion is carried out at 35°C 5d;

[0054] (III) MEC microbial acclimation: The total volume of the double-bottle MEC reactor is 600 mL and the effective volume is 500 mL. The anode of the MEC reactor is carbon brush, the cathode adopts stainless steel mesh, and the inoculum adopts the stable running MEC effluent. 1.5g/L sodium acetate is used as the carbon source, and a voltage of 1.0V is applied, and a 20Ω resistor is connected in series in the circuit at the same time. Start at room temperature of 25 °C, when the current cycle at both ends of the external resistor is stable for more than 3 cycles, it means that the domestication of anode microorganisms in the MEC is completed, and the MEC reactor is successfully started;

[0055] (IV) Hydrogen production by MEC: Mix 500 mL of excess sludge supernatant and buffer solution after anaerobic digestion pretreatment at a volume ratio of 1:2, fill with high-purity nitrogen for 30 minutes, and then feed into the MEC reactor, and add 1.0 V voltage, a 20Ω resistor is connected in series in the circuit at the same time. After 4 days of digestion, when the COD degradation rate in the electrolyte solution in the MEC reactor reaches 80%, the MEC hydrogen production step can be considered to be completed;

[0056] (V) Struvite precipitation: After the completion of the MEC reaction for hydrogen production, 57 g MgCl was added to the catholyte 2 and 100mLNH 4+ The concentration of the supernatant in the methane-producing stage of anaerobic digestion was 10 g/L, the pH value of the catholyte was adjusted to 12 with 1 mol/L NaOH solution, the magnetic stirring speed of the cathode chamber was 200 rpm/min, and the reaction time was 60 min and then allowed to stand for 1 h. The precipitated struvite was collected, freeze-dried and stored.

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Method for producing hydrogen and recycling phosphorus through electrolysis of neutral Fenton regulated residual sludge microorganism

A technology of microbial electrolysis and excess sludge

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Example Embodiment

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Example Embodiment

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Description & Claims & Application Information

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