CN106746224B - Treatment system and method for cellulosic ethanol production wastewater - Google Patents

Treatment system and method for cellulosic ethanol production wastewater Download PDF

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CN106746224B
CN106746224B CN201611229215.6A CN201611229215A CN106746224B CN 106746224 B CN106746224 B CN 106746224B CN 201611229215 A CN201611229215 A CN 201611229215A CN 106746224 B CN106746224 B CN 106746224B
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unit
communicated
water outlet
precipitation
coagulation
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CN106746224A (en
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孙岩
李春玲
张宁
宋殿霜
闫伟松
张英雪
李秀荣
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COFCO BIOCHEMICAL ENERGY (ZHAODONG) CO LTD
Cofco Corp
Cofco Nutrition and Health Research Institute Co Ltd
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COFCO BIOCHEMICAL ENERGY (ZHAODONG) CO LTD
Cofco Corp
Cofco Nutrition and Health Research Institute Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C02F2103/36—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage

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  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)

Abstract

The application provides a treatment system and a method for cellulosic ethanol production wastewater, and the system comprises: a biochemical treatment device for biochemical treatment of cellulosic ethanol production wastewater; the inlet of the clear water collecting tank is communicated with the water outlet of the biochemical treatment device; the inlet of the acidification unit is communicated with the water outlet of the clear water collecting tank; the first coagulation unit is communicated with the water outlet of the acid precipitation unit; the inlet of the first precipitation unit is communicated with the first coagulation unit, and the first precipitation unit is provided with a water outlet. This application cellulose ethanol workshop waste water is collected in clean water basin after biochemical treatment device handles. This application mainly utilizes the acidification technique to handle cellulose ethanol waste water, makes the lignin in this waste water turn into the suspended solid by the dissolved state under the acid condition and separates out, thoughtlessly congeals, deposits again, effectively gets rid of the suspended solid, realizes the purpose of desorption lignin. Simultaneously this application can obviously reduce the COD of waste water, and the treatment effect is better.

Description

Treatment system and method for cellulosic ethanol production wastewater
Technical Field
The application relates to the technical field of wastewater treatment, in particular to a treatment system and a treatment method for cellulosic ethanol production wastewater.
Background
The cellulose ethanol technology belongs to the emerging field, is a high-end clean energy technology, and is used for producing fiber fuel ethanol by adopting raw materials such as lignocellulose and the like through a biochemical route. In recent years, a great deal of capital is invested in all countries in the world, remarkable effects are achieved in all process links, and the commercialization process of the cellulosic ethanol is promoted. With the gradual implementation of various policies, the construction of cellulosic ethanol devices in China is also accelerating. In the past and ongoing research, great attention has been paid to cost problems caused by the consumption of materials such as strains for reducing the cost of cellulase and increasing the yield of ethanol, and less attention has been paid to engineering problems such as wastewater discharge which are sufficiently developed in large-scale production. The problems of treatment and resource utilization of the generated wastewater are more and more prominent while the key technology is broken through, so that the discussion of an appropriate wastewater treatment technology has very important significance.
Before some enterprises, such as the 5 million ton/year cellulosic ethanol industry, demonstrated engineering practices, it was difficult to obtain a practical solution to this problem, and even to recognize the location of the critical problem. In order to ensure the commercialization of cellulosic ethanol, the problem of wastewater produced by the production of cellulosic ethanol must be solved.
The cellulosic ethanol production wastewater has the characteristics that: the cellulose raw materials are various in types, and the composition of waste water obtained by different pretreatment methods is complex. The pretreatment of the cellulose destroys the natural structure of the lignocellulose, and inevitably causes a plurality of side reactions, and produces byproducts such as furan ring, furfural, formic acid and the like. These by-products are, without exception, introduced into the waste water, and these substances are generally difficult to biodegrade in a short time, so that the biodegradability of the waste water is reduced. After the biochemical treatment is carried out on the cellulosic ethanol production wastewater, the biochemical effluent still has higher COD and has poor treatment effect.
Disclosure of Invention
In view of this, the application provides a treatment system and a method for cellulose ethanol production wastewater, and the treatment system provided by the application is used for treating the cellulose ethanol production wastewater, and the effluent COD is lower, and the treatment effect is good.
The application provides a processing system of cellulose ethanol waste water, includes:
a biochemical treatment device for biochemical treatment of cellulosic ethanol production wastewater;
the inlet of the clear water collecting tank is communicated with the water outlet of the biochemical treatment device;
the inlet of the acidification unit is communicated with the water outlet of the clear water collecting tank;
the first coagulation unit is communicated with the water outlet of the acid precipitation unit;
the inlet of the first precipitation unit is communicated with the first coagulation unit, and the first precipitation unit is provided with a water outlet.
Preferably, the acid precipitation unit, the first coagulation unit and the first precipitation unit form an integrated first-stage coagulation precipitation tank; in the first-stage coagulating sedimentation tank body, the acid precipitation unit, the first coagulation unit and the first sedimentation unit are mutually separated and communicated through holes.
Preferably, in the first-stage coagulating sedimentation tank, the bottom of the acid precipitation unit is provided with a pump, and the top of the acid precipitation unit is provided with a top cover.
Preferably, the processing system further comprises:
the inlet of the buffer tank is communicated with the water outlet of the first precipitation unit;
the inlet of the electrolytic cell is communicated with the water outlet of the buffer tank, and the electrolytic cell is provided with a water outlet.
Preferably, the processing system further comprises:
and the inlet of the second-stage coagulating sedimentation tank is communicated with the water outlet of the electrolytic bath.
Preferably, the second-stage coagulating sedimentation tank comprises:
the inlet of the neutralization unit is communicated with the water outlet of the electrolytic bath;
the second coagulation unit is communicated with the water outlet of the neutralization unit;
the inlet of the second precipitation unit is communicated with the second coagulation unit, and the second precipitation unit is provided with a water outlet;
in the tank body of the second-stage coagulating sedimentation tank, the neutralizing unit, the second coagulating unit and the second sedimentation unit are mutually separated and communicated through holes.
The application also provides a treatment method of the cellulosic ethanol production wastewater, which comprises the following steps:
performing biochemical treatment on cellulosic ethanol production wastewater to obtain biochemical effluent;
and collecting the biochemical effluent, performing acid precipitation, and performing coagulation and precipitation to obtain effluent.
Preferably, the pH of the acidification is below 3; the acidification is carried out in the presence of a coagulant and/or coagulant aid.
Preferably, the method further comprises the following steps:
and buffering the effluent after coagulation and precipitation, and then carrying out electrocatalytic oxidation to obtain oxidized-electrolyzed effluent.
Preferably, the method further comprises the following steps:
and sequentially neutralizing, coagulating and precipitating the oxidized-electrolyzed effluent to obtain final effluent.
Compared with the prior art, the cellulose ethanol waste water processing system that this application provided mainly includes: the device comprises a biochemical treatment device, a clear water collecting tank, an acid precipitation unit, a coagulation unit and a precipitation unit. In this application, cellulose ethanol workshop waste water is collected in clear water collecting pit after biochemical treatment device handles. This application mainly utilizes the acid out technique advanced treatment cellulose ethanol waste water, and its acid out process makes the lignin in this waste water turn into the suspended solid by the dissolving state promptly under the acid condition and separates out, thoughtlessly congeals, deposits again, effectively gets rid of the suspended solid to realize the purpose of desorption lignin. Simultaneously, but this application desorption partial COD obviously reduces the COD of waste water, reaches better treatment effect. Practice shows that the COD of the inlet water is 58320mg/L, the ammonia nitrogen content is 2556.7mg/L, and the COD of the acid-out water treated by the method is 1600-1800 mg/L.
Furthermore, the COD of the final effluent in the embodiment of the application can be 230-250 mg/L, and the water quality is clear and the chroma is shallow.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a cellulosic ethanol production wastewater treatment system provided by an embodiment of the application;
fig. 2 is an effect diagram of the main water treatment stage provided in the embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The application provides a processing system of cellulose ethanol waste water, includes:
a biochemical treatment device for biochemical treatment of cellulosic ethanol production wastewater;
the inlet of the clear water collecting tank is communicated with the water outlet of the biochemical treatment device;
the inlet of the acidification unit is communicated with the water outlet of the clear water collecting tank;
the first coagulation unit is communicated with the water outlet of the acid precipitation unit;
the inlet of the first precipitation unit is communicated with the first coagulation unit, and the first precipitation unit is provided with a water outlet.
Adopt the water treatment system that this application provided, can effectively reduce cellulose ethanol waste water's COD etc. waste water treatment is effectual, does benefit to the smooth of promoting cellulose ethanol commercialization and goes on.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a cellulosic ethanol production wastewater treatment system provided in an embodiment of the present application. In fig. 1, 1 is a clear water collecting tank, 2 is a first-stage coagulation sedimentation tank, 2A is an acid precipitation unit, 2B is a first coagulation unit, 2C is a first sedimentation unit, 3 is a buffer tank, 4 is an electrolytic tank, 5 is a second-stage coagulation sedimentation tank, 5A is a neutralization unit, 5B is a second coagulation unit, and 5C is a second sedimentation unit; the biochemical processing device is not shown in fig. 1.
The application provides a cellulose ethanol waste water treatment system includes biochemical treatment device for carry out biochemical treatment to cellulose ethanol waste water. In the field of water treatment, biochemical treatment, referred to as biochemical method, is a water treatment method which utilizes microorganisms in the natural environment and decomposes organic matters and certain inorganic poisons (such as cyanides and sulfides) in wastewater through biochemical action in the microorganisms to convert the organic matters and certain inorganic poisons into stable and harmless substances, and belongs to the field of biochemical treatment methods such as an activated sludge method, a biological filtration method, a biological membrane method, an anaerobic biological method and the like. According to the different metabolism forms of microbes, the biochemical treatment of waste water can be divided into aerobic method and anaerobic method.
In this application, the biochemical treatment device has a water inlet and a water outlet. The structure and the like of the biochemical treatment device are not particularly limited, and an anaerobic unit and an aerobic unit which are commonly used in the field can be adopted. In an embodiment of the present application, the biochemical treatment apparatus includes an anaerobic unit and an aerobic unit which are sequentially communicated; the two units can be arranged independently or integrally. In some embodiments of the application, after the cellulosic ethanol workshop wastewater is treated by the biochemical treatment device, the COD of the cellulosic ethanol workshop wastewater can be reduced from 55000-60000 mg/L to 2600-2700 mg/L; the content of ammonia nitrogen can be reduced from 2000-3000 mg/L to about 80 mg/L.
In the field of water treatment, chemical oxygen demand (COD or COD)cr) The amount of oxidant consumed in the oxidative decomposition of the reduced matter in water under a certain strict condition under the action of an additional strong oxidant is expressed as mg/L of oxygen. Chemical oxygen demand reflects the degree of contamination of water with reducing substances including organic matter, nitriteIron salts, sulfides, etc., but the amount of inorganic reducing substances in general water and wastewater is relatively small, and the pollution by organic substances is common, so that COD can be used as a comprehensive index of the relative content of organic substances.
The treatment system of the embodiment of the application comprises a clear water collecting tank 1 which is provided with an inlet and a water outlet. The clean water collecting tank can be called as a clean water tank for short, an inlet of the clean water collecting tank is communicated with a water outlet of the biochemical treatment device and is used for collecting biochemical effluent treated by the biochemical treatment device so as to carry out subsequent treatment. The embodiment of the application can realize 'communication' through pipeline connection, and the arrangement form, the position and the like of the communication can be realized by adopting conventional design in the field. The structure and the like of the clear water collecting tank are not particularly limited; for example, an open square plastic bucket may be used for clean water collection. In the specific embodiment of the application, the clean water tank is an open square plastic bucket (one meter in length, width and height) with the volume of 1m3(ii) a The upper edge of the square barrel is provided with a suspended PVC water inlet which extends into the clean water tank for about 0.2 m, and the water flow rate can be 40L/h.
The treatment system of the embodiment of the application comprises an acidification unit 2A, which is provided with an inlet and a water outlet. The inlet of the acidification unit is communicated with the water outlet of the clear water collecting tank; the embodiment of the application can pump the collected biochemical effluent to the acid precipitation unit through the metering pump for acid precipitation. After the cellulosic ethanol production wastewater passes through the biochemical treatment device, a large amount of lignin is still contained. Lignin is an amorphous aromatic high polymer widely existing in plants and containing structural units of oxyphenbutamol or derivatives thereof in molecular structure, and is difficult to be effectively removed by simple biochemical treatment. In the acidification unit, the acidification process can convert lignin in the cellulosic ethanol biochemical wastewater from a dissolved state into suspended matters to be precipitated under an acidic condition, so that the subsequent effective removal of the lignin is facilitated. In addition, the acid precipitation is beneficial to removing partial COD and the like, and the treatment effect can be effectively improved.
In the embodiment of the application, the acid precipitation unit is an acid-resistant structure; the pH value of the system can be adjusted by using sulfuric acid, hydrochloric acid, nitric acid and the like, wherein the pH value of the acidification condition is required to be kept below 3. In a preferred embodiment of the present application, the pH of the acidification may be 3. In the method, lignin and the like are preferably precipitated by using sulfuric acid, and the treatment effect is best. In the present application, the acidification is preferably carried out in the presence of a coagulant and/or coagulant aid, i.e. the coagulant and/or coagulant aid is added to further settle the suspended matter and clarify the water. Wherein, the coagulant includes but is not limited to ferrous sulfate, polyaluminium chloride (PAC) and the like. According to the embodiment of the application, ferrous sulfate is preferably used as a flocculating agent (namely a coagulant), the ferrous sulfate not only has a good flocculation effect, but also can be decolorized, and also has the functions of removing heavy metal ions, removing phosphorus, sterilizing and the like, and the price is low. In the embodiment of the application, Polyacrylamide (PAM) can be used as a coagulant aid, and a corresponding commercial product can be adopted.
According to the embodiment of the application, acid and a coagulant can be added into the acid precipitation unit; the bottom of the acidification unit is preferably provided with a pump, and a peristaltic pump can be used for adding materials to the bottom. In the embodiment of the application, the top of the acid precipitation unit is provided with a top cover for collecting foam.
The treatment system of the embodiment of the application comprises a first coagulation unit 2B which is communicated with a water outlet of an acid precipitation unit 2A. The treatment system may comprise a first precipitation unit 2C having an inlet, a water outlet and a sewage drain. And the inlet of the first precipitation unit is communicated with the first coagulation unit, solid-liquid separation is realized through gravity precipitation, and acid precipitation effluent is obtained through the water outlet. The embodiment of the application can add coagulant aids such as PAM (polyacrylamide) and the like into the first coagulation unit, for example, the coagulant aids are added through a peristaltic pump. In this application, the mixture of acid out unit output can effectively get rid of suspended solid etc. through coagulating, sediment to realize desorption lignin, reduce purposes such as COD.
In the preferred embodiment of the present application, the acid precipitation unit 2A, the first coagulation unit 2B and the first precipitation unit 2C form an integrated first-stage coagulation precipitation tank 2, which has the advantages of saving floor space, improving treatment effect, reducing cost, and the like. The first-stage coagulating sedimentation tank can be called a 1-stage coagulating sedimentation tank; the expression of the acid separation unit is also called as an acid separation area (area) and a 2A area (area), and the expression of the coagulation unit and the precipitation unit can be analogized. In the first-stage coagulating sedimentation tank body in the embodiment of the application, the acid precipitation unit, the first coagulation unit and the first sedimentation unit are mutually isolated and communicated through holes, and effluent is discharged from a water outlet of the first sedimentation unit 2C. In some embodiments of the present application, the first stage coagulating sedimentation tank has an integrated structure of acid precipitation, coagulation and sedimentation; wherein, the bottom of the acid precipitation unit is provided with a pump, and the top is provided with a top cover.
In the embodiment of the present application, the processing system preferably further includes: the inlet of the buffer tank 3 is communicated with the water outlet of the first precipitation unit; and the inlet of the electrolytic cell 4 is communicated with the water outlet of the buffer tank, and the electrolytic cell is provided with a water outlet.
The embodiment of the application utilizes the buffer tank to buffer the effluent after the treatment such as acid precipitation and the like so as to facilitate the implementation and operation of the subsequent electrolytic tank. In an embodiment of the application, the buffer tank inlet is in communication with the first precipitation unit water outlet, and the buffer tank water outlet is in communication with the electrolysis tank inlet. The application prefers to arrange a groove lifting pump at the top of the buffer groove so as to obtain lifted electrolysis bath inlet water.
In the embodiment of the application, the electrolytic bath inlet water is subjected to electrocatalytic oxidation in the electrolytic bath, and oxidation-electrolysis outlet water is obtained through the electrolytic bath outlet. The oxidation is generally a Fenton oxidation technique, and is a wastewater treatment method in which Fenton reagent (Fenton reagent) is used for chemical oxidation. The Fenton reagent is prepared from H2O2And Fe2+The oxidizing agent with strong oxidizing power is prepared by mixing Fe under acidic condition (pH less than 3.5)2+As H2O2The catalyst of (3) generates OH with strong oxidation electric property and high reaction activity, and hydroxyl free radicals generate organic free radicals with refractory organic matters in aqueous solution to destroy the structure of the organic free radicals and finally oxidize and decompose the organic free radicals. While Fe2+Is oxidized into Fe3+Coagulating sedimentation is generated, and a large amount of organic matters are coagulated and removed. The Fenton oxidation method can effectively treat waste water containing nitrobenzene, ABS and other organic matters and is used for decoloring and deodorizing the waste water.
In the embodiment of the present application, the electrocatalytic oxidation is also called "microelectrolysis" reaction system, and mainly electrolyzes under a low-voltage direct current state. The built-in fillers such as conductors and insulators can play a role in intercepting pollutants, meanwhile, countless fine electrolytic cells are formed in the reaction tank under the action of an external power supply, active groups such as hydroxyl radicals are generated by electrolysis to oxidize and decompose the pollutants, and the pollutant removal mechanism is different according to different fillers. The micro-electrolysis technology is invented based on the principle of scrap iron reduction and iron-carbon primary cells, an external power supply replaces a primary cell, electricity consumption replaces iron consumption, and the main mechanisms of the micro-electrolysis technology for sewage treatment are electrolysis, oxidation reduction and electrocoagulation. Besides reducing COD, the method can also reduce chroma, demulsify and improve the biodegradability of wastewater. Therefore, the method can be used for pretreatment of high-concentration sewage or advanced treatment of low-concentration sewage. In practical application, micro-electrolysis mostly adopts an electrode plate type, namely activated carbon particles and dielectric mixed filler are filled between the electrode plates; has the advantages of short retention time, low power consumption, wide application range, flexible and convenient operation, and the like.
The specific structures of the buffer tank, the electrolytic tank and the like are not particularly limited; the embodiment of the application replenishes hydrogen peroxide and ferrous sulfate in the electrolytic bath, and controls the voltage to carry out electrocatalytic oxidation. The electrolytic tank can be called as a catalytic oxidation-micro-electrolysis reaction tank or a Fenton oxidation-micro-electrolysis integrated reaction tank, and is mainly used for treating acid-out water (the pH value is less than or equal to 3); it is provided with a water outlet and can obtain oxidation-electrolysis effluent.
In the embodiment of the present application, the processing system preferably further includes: and the inlet of the second-stage coagulating sedimentation tank 5 is communicated with the water outlet of the electrolytic tank. The second-stage coagulating sedimentation tank can be called a 2-stage coagulating sedimentation tank, an inlet of the second-stage coagulating sedimentation tank is communicated with a water outlet of the electrolytic tank, and the second-stage coagulating sedimentation tank can further coagulate and precipitate the water discharged from the electrolytic tank to obtain final discharged water. The second-stage coagulating sedimentation tank is not particularly limited in the application, and a coagulating sedimentation tank conventional in the field can be adopted.
In a preferred embodiment of the present application, the second stage coagulating sedimentation tank comprises: a neutralization unit 5A with an inlet communicated with the water outlet of the electrolytic bath; the second coagulation unit 5B is communicated with the water outlet of the neutralization unit; the inlet of the second precipitation unit 5C is communicated with the second coagulation unit, and the second precipitation unit is provided with a water outlet; in the tank body of the second-stage coagulating sedimentation tank, the neutralizing unit, the second coagulating unit and the second sedimentation unit are mutually separated and communicated through holes. Further, the second coagulation unit may communicate with the first coagulation unit through an air compressor or the like.
In the embodiment of the invention, after micro-electrolysis reaction, the pH value of the effluent is still about 4-5, so that alkaline substances such as calcium oxide, calcium hydroxide and the like need to be added for neutralization coagulation. In a preferred embodiment of the present application, the pH of the neutralization coagulation needs to be adjusted to be more than 10.5, and PAM is added at the same time, so that the neutralization coagulation can be effectively performed, and the final effluent is obtained through a precipitation unit. After the coagulation and precipitation, the COD of the effluent is about 250mg/L, and the chroma is yellowish.
Correspondingly, the application also provides a treatment method of cellulosic ethanol production wastewater, which comprises the following steps:
performing biochemical treatment on cellulosic ethanol production wastewater to obtain biochemical effluent;
and collecting the biochemical effluent, performing acid precipitation, and performing coagulation and precipitation to obtain effluent.
The water treatment method provided by the application can effectively reduce COD (chemical oxygen demand) of the cellulosic ethanol production wastewater and the like, and has a good wastewater treatment effect.
The application mainly aims at the wastewater generated in the production of cellulosic ethanol, and the wastewater is used as raw water for treatment. According to the characteristics of the wastewater from the production of cellulosic ethanol, in the embodiment of the application, the COD of the wastewater can be 55000-60000 mg/L; the content of ammonia nitrogen can be 2000-3000 mg/L.
According to the embodiment of the application, the wastewater from the cellulosic ethanol production is subjected to biochemical treatment to obtain biochemical effluent. In the embodiment of the application, after conventional anaerobic and aerobic biochemical treatment in the field, the COD of the biochemical effluent can be 2600-2700 mg/L; the ammonia nitrogen content can be about 80 mg/L.
The embodiment of the application can collect the workshop waste water after biochemical treatment device handles in the clean water basin, sends to the acidification unit through the measuring pump, carries out the acidification to desorption lignin, COD etc..
In the embodiment of the application, the acid precipitation unit is an acid-resistant structure; the pH value of the system can be adjusted by using sulfuric acid, hydrochloric acid, nitric acid and the like, wherein the pH value of the acidification condition is required to be kept below 3. In a preferred embodiment of the present application, the pH of the acidification may be 3. In the application, the lignin and the like are preferably precipitated by adopting sulfuric acid, the mass concentration of the sulfuric acid can be 20%, and the treatment effect is better. In the examples of the present application, the concentrated sulfuric acid used for the acid precipitation may be used in an amount of 3.5L/ton of water.
In the present application, the acidification is preferably carried out in the presence of a coagulant and/or coagulant aid, i.e. the coagulant and/or coagulant aid is added to further settle the suspended matter and clarify the water. Wherein, the coagulant includes but is not limited to ferrous sulfate, polyaluminium chloride (PAC) and the like. According to the embodiment of the application, ferrous sulfate is preferably used as a flocculating agent (namely a coagulant), the ferrous sulfate not only has a good flocculation effect, but also can be decolorized, and also has the functions of removing heavy metal ions, removing phosphorus, sterilizing and the like, and the price is low. In the embodiment of the application, Polyacrylamide (PAM) can be used as a coagulant aid, and a commercially available product can be used.
In the embodiment of the application, acid and a coagulant can be added into the acid precipitation unit to carry out acid precipitation coagulation, and the retention time is preferably 10min to 30min, and more preferably 15min to 25 min. In some preferred embodiments of the present application, 20% by mass of sulfuric acid and ferrous sulfate are added in the acidification unit, and the ratio is preferably 1400 mL/h: 15-20 g/h.
Then, the embodiment of the application can add coagulant aids into the coagulation unit, and obtain acid precipitation effluent through precipitation. In some preferred embodiments of the application, 3-4ppm PAM is added into the coagulation unit, namely 105-140mg/H (PAM is prepared into 1/1000, namely 105-140ml/H, and is added by a peristaltic pump); the residence time is preferably 10 to 30min, more preferably 15 to 25 min. The residence time of the embodiment in the precipitation unit can be 30-60 min, preferably 40-50 min.
After obtaining the acid-out water, the present application preferably further comprises: and buffering the effluent after coagulation and precipitation, and then carrying out electrocatalytic oxidation to obtain oxidized-electrolyzed effluent.
The embodiment of the application can collect the acid-precipitated water in the buffer tank, and then the acid-precipitated water enters the electrolytic cell through the lift pump, and the flow can be 35L/H. The embodiment of the application can adopt hydrogen peroxide and ferrous sulfate in an electrolytic tank, and carry out electrocatalytic oxidation on acid-separated water under the action of an external power supply to obtain oxidized-electrolyzed water. In the embodiment of the application, 290-300 mL/H of 10% hydrogen peroxide solution and 400-450 mL/H of 10% ferrous sulfate solution are supplemented in the electrolytic cell. The voltage of the electrocatalytic oxidation can be 18V; the retention time is 15min, and the pH value of the effluent is about 4-5.
After obtaining the oxidation-electrolysis effluent, the present application preferably further comprises: and sequentially neutralizing, coagulating and precipitating the oxidized-electrolyzed effluent to obtain final effluent.
In the embodiment of the application, alkaline substances such as calcium oxide, calcium hydroxide and the like can be added for neutralization coagulation. In some embodiments of the present application, the calcium oxide used for neutralization may be used in an amount of 1.5 to 2 kg/ton of water. In other embodiments of the present application, 105g/H of calcium hydroxide is added to prepare 10% calcium hydroxide, that is, 1050 mL/H.
In the application example, the pH value is neutralized to be above 10.5, and the effluent is discharged. PAM is preferably supplemented in the coagulation sedimentation tank at the same time, and coagulation sedimentation is effectively carried out. In some embodiments of the application, 3-4ppm PAM (105-140 mg/H) can be added (the PAM is prepared into 1/1000, namely
105-140mL/H, and adding by a peristaltic pump). The retention time of the coagulation sedimentation tank in the embodiment of the application can be 1h, and the final effluent with COD of about 250mg/L and yellowish chroma is obtained through sedimentation.
To sum up, the cellulosic ethanol production wastewater treatment system that this application provided mainly includes: the device comprises a biochemical treatment device, a clear water collecting tank, an acid precipitation unit, a coagulation unit and a precipitation unit. In this application, cellulose ethanol workshop waste water is collected in clear water collecting pit after biochemical treatment device handles. This application mainly utilizes the acid out technique advanced treatment cellulose ethanol waste water, and its acid out process makes the lignin in this waste water turn into the suspended solid by the dissolving state promptly under the acid condition and separates out, thoughtlessly congeals, deposits again, effectively gets rid of the suspended solid to realize the purpose of desorption lignin. Simultaneously, but this application desorption partial COD obviously reduces the COD of waste water, reaches better treatment effect.
For further explanation of the present application, the treatment system and method for cellulosic ethanol production wastewater provided in the present application will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present application.
In the following examples, PAM was purchased from Xinyu chemical Co., Ltd, Zhengzhou, and its molecular formula: (C)3H5NO)nEnglish: polyacrylamide, abbreviated: PAM, solid content: 90%, pH application range: 4-14, CAS: 9003-05-8; 62649-23-4; 25085-02-3; EINECS No.: 203-750-9, HS coding: 3906901000.
examples
The wastewater treatment system shown in FIG. 1 is adopted, wherein the biochemical treatment device comprises an anaerobic unit and an aerobic unit which are communicated in sequence; the clean water tank is an open square plastic bucket (one meter in length, width and height) with the volume of 1m3(ii) a The upper edge of the square barrel is provided with a suspended PVC water inlet which extends into the clean water tank for about 0.2 m, and the water flow rate is 40L/h.
The treatment capacity was 1m2And d, treating the cellulosic ethanol workshop wastewater by using an anaerobic and aerobic biochemical treatment device, collecting the wastewater in a clean water tank 1, and pumping the wastewater to a 2A area of a first-stage coagulating sedimentation tank 2 (a 1-stage coagulating sedimentation tank) by using a metering pump. 20% sulfuric acid and ferrous sulfate (1400 mL/hr: 17.5 g/hr) were added to zone 2A, and a peristaltic pump was used to add the solution to the bottom, and a top cap was placed over the top of this zone to collect the foam. The first-stage coagulating sedimentation tank 2 is provided with partitions between the tank bodies and is communicated with each other through holes; the groove body area is divided into: the 2A area is an acid precipitation area; the area 2B is a coagulation area; the 2C area is a precipitation area.
The residence time of the 2A zone is 20 min; adding 3-4ppm PAM in the 2B zone, namely 105-140mg/H (adding PAM to 1/1000, namely 105-140ml/H, adding by a peristaltic pump), wherein the retention time is 20 min. The residence time in the 2C zone is 40 min; the obtained acid precipitation effluent passes through a water outlet of the 2C area and is collected in the buffer tank 3. The above treatment steps are referred to as acid separation process, and the condition parameters of this part are shown in table 1, and table 1 is the condition parameters of the acid separation process in the examples of the present application.
TABLE 1 Condition parameters of the acid out procedure in the examples of the present application
Figure BDA0001194209920000101
Figure BDA0001194209920000111
The top of the buffer tank 3 is provided with a buffer tank lift pump, so that the flow of the inlet water of the electrolytic tank 4 is 35L/H. The COD of the buffer tank 3 is calculated according to 1600mg/L, and the electrolytic tank 4 is supplemented with 294mL/H of hydrogen peroxide (10%); ferrous sulfate (10%) 420 mL/H; the voltage is 18V; the retention time is 15min, and oxidation-electrolysis effluent is obtained. The oxidation-electrolysis condition parameters and the like are shown in table 2, and table 2 shows the optimized oxidation-electrolysis results in the examples of the present application.
The effluent of the electrolytic cell 4 flows into a 2-stage coagulating sedimentation tank 5, and the area of the tank body is divided into: the 5A area is a neutralization area; the 5B area is a coagulation area; the 5C area is a precipitation area. 105g/H of calcium hydroxide is added in the area 5A to prepare 1050ml/H of 10% calcium hydroxide; neutralizing and coagulating until pH is 10.5, and discharging the discharged water. And 4ppm PAM (140 mg/H) is added into the 5B zone (PAM is prepared into 1/1000, namely 105-140ml/H, and is added by a peristaltic pump). The retention time of the 2-level coagulating sedimentation tank 5 is 1h, after coagulation and sedimentation, the COD of the final effluent discharged from the water outlet of the 5C area is 250mg/L, and the chroma is yellowish.
The water is detected by adopting a conventional method in the field, the water outlet test results of each stage of the pilot plant test are shown in table 3 and fig. 2, the table 3 is the water outlet test result of each stage of the pilot plant test in the embodiment of the application, and fig. 2 is the effect diagram of the main water treatment stage provided by the embodiment of the application.
According to the embodiment, the COD of the inlet water is 58320mg/L, the ammonia nitrogen content is 2556.7mg/L, the COD of the acid-precipitated water treated by the method is 1600-1800 mg/L, the chroma is shallow, and the water quality is clear. The method mainly utilizes the acidification technology to deeply treat the cellulosic ethanol wastewater, realizes the purposes of removing lignin, COD and the like, effectively reduces the COD of the wastewater, has better treatment effect, and has great significance for promoting the commercialization of cellulosic ethanol to be smoothly carried out.
TABLE 2 results of the optimization of the oxidation electrolysis in the examples of the present application
Figure BDA0001194209920000112
TABLE 3 Water test results of the various stages of the test in the examples of the present application
Figure BDA0001194209920000121

Claims (4)

1. A treatment method of cellulosic ethanol production wastewater comprises the following steps:
performing biochemical treatment on cellulosic ethanol production wastewater to obtain biochemical effluent with reduced COD and ammonia nitrogen content;
collecting the biochemical effluent, performing acid precipitation, and performing coagulation and precipitation to obtain effluent; the pH value of the acid precipitation is below 3; the acid precipitation is carried out in the presence of a coagulant and a coagulant aid;
buffering the effluent after coagulation and precipitation, and then carrying out electrocatalytic oxidation to obtain oxidation-electrolysis effluent;
sequentially neutralizing, coagulating and precipitating the oxidized-electrolyzed effluent to obtain final effluent;
the processing system adopted by the processing method comprises the following steps:
a biochemical treatment device for biochemical treatment of cellulosic ethanol production wastewater;
the inlet of the clear water collecting tank is communicated with the water outlet of the biochemical treatment device;
the inlet of the acidification unit is communicated with the water outlet of the clear water collecting tank;
the first coagulation unit is communicated with the water outlet of the acid precipitation unit;
the inlet of the first precipitation unit is communicated with the first coagulation unit, and the first precipitation unit is provided with a water outlet;
the inlet of the buffer tank is communicated with the water outlet of the first precipitation unit;
the inlet of the electrolytic cell is communicated with the water outlet of the buffer tank, and the electrolytic cell is provided with a water outlet;
and the inlet of the second-stage coagulating sedimentation tank is communicated with the water outlet of the electrolytic bath.
2. The treatment method according to claim 1, wherein the acid precipitation unit, the first coagulation unit and the first precipitation unit form an integrated first-stage coagulation precipitation tank; in the first-stage coagulating sedimentation tank body, the acid precipitation unit, the first coagulation unit and the first sedimentation unit are mutually separated and communicated through holes.
3. The treatment method according to claim 2, wherein in the first-stage coagulating sedimentation tank, a pump is arranged at the bottom of the acidification unit, and a top cover is arranged at the top of the acidification unit.
4. The treatment method according to any one of claims 1 to 3, wherein the second-stage coagulating sedimentation tank comprises:
the inlet of the neutralization unit is communicated with the water outlet of the electrolytic bath;
the second coagulation unit is communicated with the water outlet of the neutralization unit;
the inlet of the second precipitation unit is communicated with the second coagulation unit, and the second precipitation unit is provided with a water outlet;
in the tank body of the second-stage coagulating sedimentation tank, the neutralizing unit, the second coagulating unit and the second sedimentation unit are mutually separated and communicated through holes.
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