CN113461170B - Method and equipment for rapidly culturing autotrophic denitrification cable bacteria and application - Google Patents

Abstract

The invention relates to the technical field of biological treatment of water, wastewater or sewage, and discloses a method, equipment and application for quickly culturing autotrophic denitrifying cable bacteria, wherein the method comprises the steps of constructing an environment specially suitable for the growth of the autotrophic denitrifying cable bacteria, adopting an electric field to enrich the autotrophic denitrifying cable bacteria in the environment, then adopting the autotrophic denitrifying cable bacteria to remove nitrate nitrogen and nitrite nitrogen in the sewage, not needing to input organic matters as a carbon source, not causing secondary pollution, and not needing to inoculate specially screened strains in advance for culture; thereby greatly reduced sewage denitrification facility's the use degree of difficulty, equipment cost, and running cost, and even the bacterial colony in the device suffers to destroy and also can recover very fast.

Description

Method and equipment for rapidly culturing autotrophic denitrification cable bacteria and application

Technical Field

The invention relates to the technical field of biological treatment of water, wastewater or sewage, in particular to a method, equipment and application for quickly culturing autotrophic denitrifying cable bacteria.

Background

The three main indicators in the sewage are organic matter content (often expressed as oxygen demand), total nitrogen and total phosphorus, and the three indicators are mainly reduced in the sewage treatment process. Generally speaking, for general sewage, the aerobic digestion is carried out in the aeration tank to effectively remove organic matters and nitrogen and phosphorus in the sewage, and for sewage with a particularly high pollution degree, most of the organic matters are removed in an anaerobic digestion mode and then are further treated in the aeration tank.

At present, the removal of nitrate nitrogen which is formed by oxidizing ammonia nitrogen and organic nitrogen by nitrifying bacteria in an aeration tank is a big problem disturbing sewage treatment. Because nitrate nitrogen is very stable, and many microorganisms in the aeration tank lack a biochemical mechanism for utilizing the nitrate nitrogen as a nitrogen source, the content of the nitrate nitrogen in the aeration tank is difficult to reduce, so that the total nitrogen of finally discharged sewage is over-standard.

None of the current methods for removing nitrate nitrogen are satisfactory. Chemical methods, such as ion exchange and reverse osmosis, require large amounts of expensive consumables and are costly. At present, the main nitrate nitrogen removal mode is nitrification liquid internal reflux, namely, sewage treated by an aeration tank flows back into an anoxic tank, denitrification treatment is carried out by denitrifying bacteria in the anoxic tank, and the reflux ratio is usually 100-400%. However, it is clear that this method involves back-flow, causing back-mixing, greatly reducing the efficiency of the whole sewage treatment plant, increasing the energy consumption and cost of sewage treatment. The other mode is to arrange a special denitrification deep bed filter for denitrification treatment, but in the mode, heterotrophic denitrifying bacteria are mainly utilized, and organic matters are additionally input as carbon sources, so that secondary pollution is caused.

Naturally, denitrification treatment of sewage using autotrophic denitrifying bacteria has been attempted (CN101973629B, CN104150592B, CN106315848B), but since autotrophic denitrifying bacteria grow slowly and weakly, it is necessary to inoculate a strain exclusively in the apparatus and culture it for a long time in advance, and sewage treatment can be performed after the bacterial colony is cultured to a certain scale. And once the colony is destroyed, the whole device is scrapped, and colony culture needs to be started from the beginning, so the method is not popularized yet.

The cable bacteria are special bacteria which are widely distributed on the surface of a river bed or a sea bed, are long-strip-shaped and can be connected end to end in the growth process to form a cell long chain consisting of a plurality of bacteria. The long chain of cells has good conductivity, one end is connected with an electron donor (generally organic matters in a river bed), and the other end is connected with an electron acceptor (generally oxygen or metal oxide), so that different substances on the surface and in the depth of river mud/sea mud are fully utilized. Due to the characteristics, the growth and metabolism of the cable bacteria are fast, and the cable bacteria have the characteristic of strong electric field trend, so that a large amount of cable bacteria can be quickly enriched after the electrified electrode is inserted into the sea bed or river bed.

It has been found that some of the cable bacteria have denitrification capability (Yang Y, Zhao Y, Tang C, et al. Novel pyrolysis and aluminum sludge as substrates in a two-contaminated confined and-microbial fuel cell [ J ]. Journal of Cleaner Production, 2021, 293(1): 126087.), can utilize metal sulfide as an electron donor and nitrate nitrogen as an electron acceptor, and can be used for the autotrophic life.

Disclosure of Invention

The invention provides a method, equipment and application for rapidly culturing autotrophic denitrification cable bacteria.

The technical problem to be solved is that: the existing sewage denitration method is unsatisfactory, the chemical method is high in cost, the efficiency of the whole sewage treatment device can be reduced by a nitrifying liquid internal reflux method, and secondary pollution can be caused by a denitrification deep bed filter method.

In order to solve the technical problems, the invention adopts the following technical scheme: a method for rapidly culturing autotrophic denitrifying cable bacteria comprises the following steps:

the method comprises the following steps: constructing a light-shielding anaerobic environment which takes solid inorganic matters as a final electron donor and a colony adhesion base and inorganic matters as a carbon source as a culture medium, and applying an electric field for promoting electrons to leave the final electron donor in the final electron donor;

step two: taking natural water or domestic sewage containing autotrophic denitrification cable bacteria as water to be treated, wherein the water to be treated contains nitrate and/or nitrite serving as a final electron acceptor; the water to be treated is caused to flow continuously through the culture medium.

Further, the electric field in the medium is provided by two metal electrodes which are electrically connected with each other and have different electron work functions and are arranged in the medium.

Furthermore, the water to be treated flows through the two metal electrodes in sequence and then contacts with the final electron donor in the culture medium, the metal electrode which flows through first is called a prior electrode, the metal electrode which flows through later is called a subsequent electrode, the electron work function of the subsequent electrode is smaller than that of the prior electrode, and the prior electrode, the subsequent electrode and the final electron donor are sequentially distributed into three layers which are in contact in the flow direction of the water to be treated in the culture medium.

Further, the final electron donor is a metal sulfide, and the culture medium further comprises a pH control agent for preventing the pH value in the culture medium from being too low, and an oxygen scavenger for removing dissolved oxygen in the water to be treated.

Further, the rear electrode is a metal with metal activity greater than that of hydrogen and not greater than that of magnesium, the standard electrode potential of the rear electrode is greater than that of the front electrode, and the rear electrode is used as a pH control agent.

Furthermore, the prior electrode is a spongy metal capable of reacting with oxygen dissolved in the water to be treated, and the prior electrode is an oxygen scavenger.

Further, the former electrode is sponge iron, the latter electrode is aluminum, and the metal sulfide is pyrite.

The utility model provides an equipment of cultivateing autotrophic denitrification cable bacterium fast, adopts foretell method of cultivateing autotrophic denitrification cable bacterium fast to cultivate autotrophic denitrification cable bacterium, and includes the inclosed tube-shape shell of vertical setting and from the top down sets up in proper order the sponge iron layer of piling up by the sponge iron in the tube-shape shell and pile up the aluminium lamination that forms by garrulous aluminium and pile up the pyrite layer that forms by the pyrite ore, set up the water inlet that is higher than the sponge iron layer on the tube-shape shell and be less than the delivery port on pyrite layer.

Further, the pyrite layer is erected in the cylindrical shell through a bearing plate provided with a hole for water to be treated to flow through, the water outlet is lower than the bearing plate, and an air-water back flushing port for mixing back washing gas and back washing water to enter is further arranged on the barrel below the bearing plate.

A sewage denitrification method, which makes sewage flow in from the water inlet of the equipment for rapidly culturing autotrophic denitrifying cable bacteria and flow out from the water outlet to carry out denitrification.

Compared with the prior art, the method, the equipment and the application for rapidly culturing the autotrophic denitrification cable bacteria have the following beneficial effects:

in the invention, autotrophic denitrification cable bacteria are adopted to remove nitrate nitrogen and nitrite nitrogen, organic matters are not required to be added as carbon sources, and secondary pollution is not caused;

in the invention, the main consumable materials are minerals such as pyrite, which have wide sources and very low price, so that the operation cost of the device is greatly reduced, and compared with the existing denitrification deep bed filter, the operation cost can be reduced by more than 40%;

the device disclosed by the invention is simple and compact in structure, does not need to carry out backflow, does not reduce the efficiency of the whole sewage treatment device, can adopt smaller-scale equipment to complete sewage treatment work compared with a nitrifying liquid internal backflow method, and greatly reduces equipment investment; compared with a denitrification deep bed filter, the method can save an expensive carbon source dosing quantitative control system (used for accurately controlling the carbon source dosing amount, and avoiding the problems of excessive carbon source, COD (chemical oxygen demand) in effluent exceeding and low denitrification efficiency due to insufficient carbon source), and can also obviously reduce equipment investment;

according to the invention, by constructing an environment specially suitable for the growth of autotrophic denitrifying cable bacteria and adopting an electric field to enrich the autotrophic denitrifying cable bacteria in the environment, strains specially screened in advance do not need to be inoculated and cultured, so that the use difficulty of the device is greatly reduced, and the device can be quickly recovered even if bacterial colonies in the device are damaged;

in the invention, the electric field is adopted to strengthen the movement of electrons in the cable bacteria, thereby strengthening the metabolic process of the cable bacteria and improving the denitration efficiency;

in the invention, the electric field is provided by adopting the contact potential difference of aluminum and iron, and no additional power supply is needed;

according to the invention, electrochemical corrosion of aluminum is adopted to form aluminum hydroxide, so that pH imbalance in the device caused by acidic substances generated by bacteria metabolism of the autotrophic denitrification cable is avoided, bacterial colonies grow under stable pH and the shell of the device is protected, and the aluminum hydroxide can flocculate particles in sewage to improve the quality of the sewage; the aluminum can also strengthen the oxygen removing effect of the sponge iron when being corroded.

Drawings

FIG. 1 is a schematic structural diagram of a method for rapidly culturing autotrophic denitrifying cable bacteria according to the present invention;

the device comprises a sponge iron layer, a 2-aluminum layer, a 3-pyrite layer, a 4-supporting plate, a 5-cylindrical shell, a 51-water inlet, a 52-water outlet, a 53-air-water back flushing port, a 61-water outlet valve, a 62-back flushing air valve and a 63-back flushing water valve, wherein the sponge iron layer is arranged on the surface of the sponge iron layer, the 2-aluminum layer is arranged on the surface of the pyrite layer, the 4-supporting plate is arranged on the surface of the cylindrical shell, and the 63-back flushing water valve is arranged on the surface of the cylindrical shell.

Detailed Description

As shown in FIG. 1, a method for rapidly culturing autotrophic denitrifying cable bacteria comprises the following steps:

the method comprises the following steps: constructing a light-shielding anaerobic environment which takes solid inorganic matters as a final electron donor and a colony adhesion base and inorganic matters as a carbon source as a culture medium, and applying an electric field for promoting electrons to leave the final electron donor in the final electron donor;

step two: taking natural water or domestic sewage containing autotrophic denitrification cable bacteria as water to be treated, wherein the water to be treated contains nitrate and/or nitrite which is used as a final electron acceptor; the water to be treated is caused to flow continuously through the culture medium.

The environment which is light-resistant, anaerobic, has a colony adhesion base, the final electron donor is inorganic matter, and the carbon source is inorganic matter is only suitable for the growth of autotrophic denitrifying bacteria, and is particularly suitable for the growth of autotrophic denitrifying cable bacteria because of the existence of the electric field which promotes the electrons to leave the final electron donor. Carbon dioxide or carbonate dissolved in the sewage can be used as the carbon source.

The electric field in the culture medium is provided by two metal electrodes which are arranged in the culture medium and are electrically connected with each other and have different electron work functions, namely the electric field is provided by the contact potential difference formed after the two metals are contacted.

The water to be treated flows through the two metal electrodes in sequence and then contacts with the final electron donor in the culture medium, the metal electrode which flows through first is called as a prior electrode, the metal electrode which flows through later is called as a subsequent electrode, the electron work function of the subsequent electrode is smaller than that of the prior electrode, and the prior electrode, the subsequent electrode and the final electron donor are sequentially distributed into three layers which are in contact along the flowing direction of the water to be treated in the culture medium. After contact, the electrons at the back electrode move to the front electrode due to the smaller work function of the electrons, so that the electrons are lack of electrons, and are positively charged, and the potential is increased.

After the rear electrode is contacted with the front electrode, the potential of the rear electrode is increased to form an electric field for promoting electrons to move to the rear electrode, when the autotrophic denitrification cable bacteria grow, one end of a long cell chain can be lapped on a final electron donor, and the other end of the long cell chain is lapped on the rear electrode to grow, and the long cell chain can more effectively transfer electrons to carry out metabolism under the action of the electric field.

The final electron donor is metal sulfide, and the culture medium further comprises a pH control agent for preventing the pH value in the culture medium from being too low, and an oxygen scavenger for removing oxygen dissolved in the water to be treated. When metal sulfide is used as a final electron donor, autotrophic denitrification cable bacteria metabolize to generate a lot of sulfuric acid and acid salt, so that the pH value in the device is reduced, the container is corroded, the autotrophic denitrification cable bacteria are not beneficial to growing, and the pH value is required to be controlled to be about 7.5. The oxygen scavenger has the function of removing dissolved oxygen in water to be treated and avoiding the growth of aerobic bacteria from influencing denitrification.

The back electrode is made of metal with metal activity larger than that of hydrogen and not larger than that of magnesium, the standard electrode potential of the back electrode is larger than that of the front electrode, and the back electrode is used as a pH control agent. The rear electrode and the front electrode form a galvanic cell, the rear electrode close to the final electron donor forms alkaline substances under electrochemical corrosion, acid substances generated by metabolism of cable bacteria are neutralized, and oxygen dissolved in water to be treated can obtain electrons on the front electrode to be consumed. The process of oxygen reduction consumes electrons, so that the electrons move from the rear electrode to the front electrode, the electron deficiency degree of the rear electrode is further improved, the potential of the rear electrode is favorably maintained and improved, and the potential is higher on the basis of the contact potential.

The first electrode is a spongy metal capable of reacting with oxygen dissolved in the water to be treated, and the first electrode is an oxygen scavenger. In this example, the leading electrode is sponge iron, the trailing electrode is aluminum, the metal sulfide is pyrite, and the aluminum layer 2 and the pyrite layer 3 are cross-mixed.

The need for a prior electrode that can also react with oxygen to consume oxygen is due to the following:

the primary cell voltage is calculated according to the nernst equation and the current is then calculated according to the butler-fowler equation, which shows that in environments with very low ionic strength, such as sewage, the amount of electrons provided per unit time by aluminium is actually small and is generally insufficient to completely reduce the dissolved oxygen in the water, so that a preceding electrode is required to react with oxygen to consume oxygen. The sponge iron is used as a prior electrode, so that oxygen can be consumed, and the contact area with water to be treated can be increased; aluminum can also produce aluminum hydroxide, neutralize acidic species and act as a flocculant.

The electrode products for iron and aluminum as galvanic electrodes at pH 7.5 were as follows:

aluminum hydroxide is always generated on the aluminum, and the iron is divided into the following three conditions according to the dissolved oxygen amount in water to be treated:

if oxygen is almost absent, hydrogen is mainly generated;

if more oxygen is available, hydroxide radical is mainly generated;

the amount of oxygen is large, and the electrons provided by aluminum per unit time are not enough to reduce the oxygen in the water to be treated flowing through the aluminum per unit time, so that the dissolved oxygen can directly react with iron to generate iron oxide while generating hydroxyl radicals, which is the case in the embodiment.

The utility model provides an equipment of autotrophic denitrification cable bacterium is cultivateed fast to adopt foretell a method of autotrophic denitrification cable bacterium cultivates autotrophic denitrification cable bacterium, and include vertical inclosed tube-shape shell 5 that sets up, and from the top down set gradually in tube-shape shell 5 by the piled up sponge iron layer 1 that forms of sponge iron, pile up the aluminium lamination that forms by garrulous aluminium 2, and pile up the pyrite layer 3 that forms by the pyrite, set up the water inlet 51 that is higher than sponge iron layer 1 on the tube-shape shell 5, and be lower than the delivery port 52 of pyrite layer 3. The tubular shell 5 is made of metal, plays a role in electrostatic shielding, and avoids the electric field leakage of the sponge iron layer 1 and the aluminum layer 2.

The pyrite layer 3 is erected in the cylindrical shell 5 through a bearing plate 4 provided with a hole for water to be treated to flow through, a water outlet 52 is arranged lower than the bearing plate 4, and a gas-water back flushing port 53 for mixing back flushing gas and back flushing water to enter is further arranged on the cylinder below the bearing plate 4.

Note that some sludge containing autotrophic denitrifying cable bacteria, such as secondary sedimentation tank sludge, river mud, etc., may be added to the culture medium in advance to accelerate the culture process. In this example, some secondary sedimentation tank sludge was added to the pyrite deposit 3. Certainly, some sludge is inevitably mixed during water pumping, and the water also carries bacteria, so that if the sludge is not added, the corresponding effect can be achieved after long-time culture.

The supporting plate 4 is provided with dense hemp pores which can also play the role of a gas-liquid distributor when the gas-water backwashing operation is carried out, and a liquid distributor can also be arranged above the sponge iron, but in general, the sewage entering the device has slow flow speed and sufficient time for distribution, and the liquid distributor is not necessary.

The case of sewage treatment using this device is as follows:

the sewage from the secondary sedimentation tank is lifted by the pump, enters the device along the water inlet 51, flows out along the water outlet 52 after being treated, and the pipeline of the water outlet 52 is provided with a water outlet valve 61. The air-water back flushing port 53 is communicated with a back flushing water pipe and a back flushing air pipe, after the back flushing water pipe and the back flushing air pipe are combined, the back flushing water pipe enters the device along the air-water back flushing port 53, the back flushing water pipe is provided with a back flushing water pipe, and the back flushing air pipe is provided with a back flushing air valve 62.

The cylindrical shell 5 is a carbon steel tank body with phi of 0.5 multiplied by 1.3m, a bearing plate 4 is provided with a hole with phi of 2mm, a pyrite layer 3 is 25cm thick, an aluminum layer 2 is 10cm thick, and a sponge iron layer 1 is 10cm thick. The control conditions in the apparatus are as follows: PH =7.5, and the detention time is 4.8h under dark, anaerobic and hydraulic conditions.

The COD concentration of the sewage is 30-60 mg/L, the total nitrogen of the inlet water is 21-28 mg/L, the total phosphorus is 0.75mg/L, the density is 1.008g/L, and the ratio of VSS to SS in the device is 0.75; the water inflow per day is controlled to be 2m3/d through a valve, and the filtering speed is 0.42m3/m 2/h.

The longer the device is used, the bacterial colony of cable bacteria in the device is continuously developed, so the denitrification efficiency is also continuously improved, the total nitrogen removal rate reaches 35 percent within 5 days, the total nitrogen removal rate reaches 67 percent within 12 days, the total nitrogen removal rate reaches 75.6 percent within 20 days; after 21 days of use, the total nitrogen removal rate reaches 89.6%, and the removal rate is not obviously increased.

If the filtering speed of the device is reduced, the water outlet valve 61 is closed, the backwashing air valve 62 is opened, air-water backwashing is carried out firstly, then the backwashing water valve 63 is opened for air-water backwashing, and finally the backwashing air valve 62 is closed for water backwashing alone. After the completion of the operation, the backwash water valve 63 is closed and the outlet valve 61 is opened.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.

Claims (4)

1. A method for rapidly culturing autotrophic denitrification cable bacteria is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: constructing a light-shielding anaerobic environment which takes solid inorganic matters as a final electron donor and a colony adhesion base and inorganic matters as a carbon source as a culture medium, and applying an electric field for promoting electrons to leave the final electron donor in the final electron donor;

step two: taking natural water or domestic sewage containing autotrophic denitrification cable bacteria as water to be treated, wherein the water to be treated contains nitrate and/or nitrite serving as a final electron acceptor; continuously flowing water to be treated through the culture medium;

the electric field in the culture medium is provided by two metal electrodes which are arranged in the culture medium, are mutually electrically connected and have different electronic work functions;

the water to be treated flows through the two metal electrodes in sequence and then contacts with a final electron donor in the culture medium, the metal electrode which flows through first is called a prior electrode, the metal electrode which flows through later is called a subsequent electrode, the electron work function of the subsequent electrode is smaller than that of the prior electrode, and the prior electrode, the subsequent electrode and the final electron donor are sequentially distributed into three layers which are in contact with each other in the culture medium along the flowing direction of the water to be treated;

the former electrode is sponge iron, the latter electrode is aluminum, and the electron donor is pyrite.

2. The utility model provides an equipment of autotrophic denitrification cable bacterium is cultivateed fast which characterized in that: the method for rapidly culturing the autotrophic denitrifying cable bacteria according to claim 1 comprises a vertically arranged closed cylindrical shell (5), and a spongy iron layer (1) formed by piling spongy iron, an aluminum layer (2) formed by piling crushed aluminum, and a pyrite layer (3) formed by piling pyrite, which are sequentially arranged in the cylindrical shell (5) in a layered manner from top to bottom, wherein the cylindrical shell (5) is provided with a water inlet (51) higher than the spongy iron layer (1) and a water outlet (52) lower than the pyrite layer (3).

3. The apparatus for rapidly culturing autotrophic denitrifying cable bacteria according to claim 2, wherein: the device is characterized in that the pyrite layer (3) is erected in the cylindrical shell (5) through a bearing plate (4) with a hole for water to be treated to flow through, the water outlet (52) is lower than the bearing plate (4), and an air-water back flushing port (53) for mixing back flushing gas and back flushing water and then entering is further arranged on a barrel below the bearing plate (4).

4. A sewage denitrification method is characterized in that: denitrification is performed by flowing sewage from the water inlet (51) and from the water outlet (52) of an apparatus for rapidly culturing autotrophic denitrifying cable bacteria according to any one of claims 2 to 3.

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