CN101519267B - A combined treatment process for high-concentration organic wastewater - Google Patents

Abstract

The present invention aims at the difference in biodegradability of a large amount of organic matter in the current high-concentration organic wastewater, and according to the current status of high-concentration organic wastewater treatment technology, provides a high-concentration organic wastewater "micro-aerobic" with high removal efficiency and wide adaptability Bacterial treatment method + chemical oxidation method + activated sludge method" combined treatment process. The process first uses micro-aerobic bacterial treatment to remove most of the biodegradable organic matter, so that the chemical oxidation method basically treats the refractory organic matter; then the chemical oxidation method is used to improve the biodegradability of wastewater, laying the foundation for subsequent biological treatment. The basis; finally, the activated sludge method is used as a post-treatment to ensure the quality of the effluent. This process can be directly applied to different types of high-concentration organic wastewater including high oil, high sulfur and high ammonia, and has the advantages of high removal efficiency, low sludge output and wide application range.

Description

A combined treatment process for high-concentration organic wastewater

technical field

The invention belongs to the fields of environmental engineering and wastewater treatment engineering, and in particular relates to a combined process of "micro-aerobic bacteria treatment method + chemical oxidation method + activated sludge method". The combined process is widely applicable to different types of high-concentration organic wastewater including fermentation industrial wastewater, sugar wastewater, printing and dyeing wastewater, food processing wastewater, and landfill leachate.

Background technique

With the rapid growth of my country's economy, a large amount of sewage discharge has caused water pollution problems to become more and more serious. It is predicted that China's current industrial wastewater accounts for more than 70% of the total wastewater, including fermentation industrial wastewater (such as citric acid water, brewing wastewater, antibiotic wastewater, etc.), sugar wastewater, printing and dyeing wastewater, food processing wastewater (such as salad oil processing Wastewater, etc.), landfill leachate, etc. belong to high-concentration organic wastewater, which is characterized by extremely high concentration, COD value generally reaches tens of thousands or even hundreds of thousands mg/L, and contains a wide variety of organic substances, except for a large number of biodegradable substances. In addition, it may also include a large number of non-biodegradable substances (such as fermentation residues, synthetic detergents, organochlorine pesticides, polychlorinated biphenyls, antibiotics, endocrine disruptors, organophosphorus pesticides, surfactants, organic dyes, etc.), These refractory substances have poor biodegradability and are not easily degraded by microorganisms. Many of them even have relatively high biological toxicity. Although the content is low, they have a great impact on the environment and human health. Once discharged, they will have a serious impact on the environment.

At present, high-concentration organic wastewater that is difficult to degrade or contains toxic organic substances can be treated by a single chemical oxidation method. For example, the application number is 200510100249.0, and the name is a method for treating polyvinyl alcohol wastewater by catalytic oxidation process. The publication number is the invention patent of CN1944281A. Fast, good effect, and for example, the application number is 02144567.2, the name is a method for catalytic wet oxidation treatment of high phenolic wastewater, and the invention patent with the publication number CN1498861A adopts precious metal and rare earth metal catalysts with extremely high catalytic activity. Improve the efficiency of catalytic wet oxidation reaction and improve the biodegradability of wastewater. Another example is the application number 200510026670.1, which is a method for catalytic oxidation treatment of high-concentration wastewater. Then add appropriate air, waste water, and solid catalyst into the catalytic oxidation tower to form a three-phase catalytic oxidation, which is used to treat high-concentration organic waste water with high chroma and high salt content, easy to operate, no secondary pollution, and no dross generation . The application number is 200410014620.7, and the name is the pretreatment method of high-concentration, refractory industrial wastewater. When the pH is 6-7, the scum is separated by air flotation, and when the pH is 8-9, coagulation is separated and precipitated, which can greatly improve the biodegradability of wastewater. Although the ideal treatment effect can be obtained by directly using chemical oxidation, it has the disadvantage of high treatment cost, which affects the wide application of chemical oxidation.

In order to reduce operating costs, more and more attention has been paid to the combined process of using chemical oxidation as pre-treatment and biological method as post-treatment. For example, the application number is 200410040058.5, the name is Ultrasonic Catalytic Oxidation-Biological Treatment of Refractory Organic Wastewater, the publication number is CN1594146A invention patent, the application number is 200410022411.7, the name is ozone + biochemical method for treating wastewater containing natural gas antifreeze, publication number It is the invention patent of CN1689992A, the application number is 200310122764.X, the name is organic wastewater treatment process, the publication number is CN1631818A invention patent, the application number is 02136127.4, the name is catalytic oxidation-biochemical combined treatment method and device for refractory organic wastewater, The invention patent with the publication number CN1468816A, the application number is 200610041550.3, the coking wastewater treatment method with the oxidation of tetravalent manganese compound, chemical precipitation and biochemical combination, the invention patent with the publication number CN1927744A, the application number is 03146091.7, the name is a An integrated process and device for oilfield drilling wastewater treatment, the invention patent with the publication number CN1569695A, the application number is 200610034589.2, the multiple combination process for the treatment of high-concentration refractory organic wastewater, the invention patent with the publication number CN101041531A, and the application number It is 03131943.2, the name is high-concentration organic nitrogen compound wastewater treatment system and its treatment process, and the publication number is the invention patent of CN1480412A. They all use chemical oxidation method as pretreatment (including ultrasonic method, ozone method, tetravalent manganese method, iron carbon Micro-electrolysis, Fenton oxidation, etc.), and the aerobic or anaerobic method is used as post-treatment to ensure the quality of effluent water, which reduces the operating cost compared with a single chemical oxidation method. However, this combined process still has the defect of high treatment cost when dealing with many high-concentration organic wastewaters, mainly because many high-concentration organic wastewaters often contain a large amount of biodegradable substances in addition to refractory organic substances, and due to the Selective oxidation cannot be achieved. When chemical oxidation is used as pretreatment, in addition to the oxidation of refractory organic substances, a large amount of oxidants are consumed on biodegradable substances, so that the consumption of oxidants greatly exceeds the actual demand.

In view of the characteristics of high-concentration organic wastewater, the use of biological pretreatment to fully remove biodegradable organic matter and then the "chemical oxidation method + biological method" is undoubtedly the most rationally designed combined process, which can minimize chemical oxidation and The operating cost of the entire process. For example, the application number is 200310103223.2, and the name is a treatment method for high-concentration organic wastewater. The invention patent with the publication number CN1611457A adopts the combined process of "anaerobic biological filter-Fenton reagent oxidation-contact oxidation method". Fully remove biodegradable organic matter, so that the target of chemical oxidation treatment is basically refractory biodegradable organic matter, while chemical oxidation method is mainly used to improve biodegradability and lay the foundation for subsequent biological treatment, so it has the lowest chemical oxidation cost and process operation cost. However, the anaerobic method still has some shortcomings when used as a pretreatment, for example, the affinity of anaerobic microorganisms to oil is low, and the anaerobic products with high concentrations of sulfate have higher toxicity to methanogens, etc. , The limitations of the anaerobic method determine that the application of the combined process of "anaerobic method + chemical oxidation method + biological treatment method" in the treatment of high-concentration organic wastewater has certain limitations.

In fact, in addition to the anaerobic method, many biological treatment technologies targeting high-concentration organic wastewater have already been developed, among which new biological treatment technologies such as yeast treatment and micro-aerobic bacteria treatment can be directly applied to high-concentration organic wastewater. Sulfur or high-oil-type high-concentration organic wastewater has achieved good treatment effects. In some occasions, it can be used as an alternative technology for anaerobic method with a wider range of applications. For example, the application number is 200510130318.2, the name is a multi-stage yeast low-oxygen treatment process and method for high-concentration organic wastewater, the invention patent with the publication number CN1807285A, the application number is 200510130317.8, and the name is Yeast for high-concentration organic wastewater Low-oxygen SBR process and device, the patent of invention with the publication number CN1807284A, the application number is 200510123100.4, the method of microaerobic hydrolysis acidification pretreatment of organic wastewater containing high concentration of sulfate, the patent of invention with the publication number CN1803670A, and the application number is 200710106974.8, titled Microaerobic Bacteria Treatment Method for High Concentration Organic Wastewater, invention patent with publication number CN101058464A, etc. Among them, the treatment method of micro-aerobic bacteria depends on the treatment object (mainly to remove organic matter, there is no significant amount of nitrate nitrogen or nitrite nitrogen in the target wastewater, and microorganisms only absorb ammonia nitrogen for the synthesis of cell matter and cannot utilize nitrate nitrogen or nitrite nitrogen) Different from the facultative biological treatment method (mainly to remove nitrate nitrogen or nitrite nitrogen, there must be a significant amount of nitrate nitrogen or nitrite nitrogen and organic matter in the target wastewater at the same time to allow facultative denitrification to occur. For example, the application number is 200410034973.3, The name is a high-efficiency wastewater treatment process, the publication number is CN1689993A invention patent), it uses micro-aerobic bacteria as the main body of treatment, and the microbial metabolism process is complete under micro-aerobic conditions, which can completely remove high-concentration organic waste like aerobic treatment. For biodegradable organic matter in wastewater, the aeration cost is about 5% or even lower than that of aerobic conditions, which saves operating costs, lowers the sludge yield, and is more applicable than anaerobic processes.

It can be seen from the above-mentioned invention patents that the current biological wastewater treatment technology has a certain distance from cost-effectiveness in the treatment of high-concentration organic wastewater, and there is still a certain distance to meet the requirements of a wide range of applications. A new type of combined treatment process for high-concentration organic wastewater is developed, and It has very practical significance to make it highly efficient, economical and widely adaptable to different types of wastewater.

Contents of the invention

The present invention aims at the characteristic that the biodegradability of organic substances in the current high-concentration organic wastewater is quite different, and according to the current status of high-concentration organic wastewater treatment technology, it provides a more efficient, economical and widely applicable high-concentration organic wastewater. Wastewater "micro-aerobic bacterial treatment method + chemical oxidation method + activated sludge method" combined treatment process. The process includes the following three stages: first, micro-aerobic bacterial treatment is used to remove most of the biodegradable organic matter under micro-aerobic conditions, so that the chemical oxidation method basically treats difficult biodegradable organic matter; Improve the biodegradability of wastewater and lay the foundation for subsequent biological treatment; finally, the activated sludge method is used as post-treatment to ensure the quality of effluent water. The process degrades the differences in the biodegradability of organic matter in high-concentration organic wastewater in stages, and applies the micro-aerobic bacteria treatment method to the pretreatment of the combined process, which minimizes the operating cost of the chemical oxidation method and makes the whole process The design of the combined process tends to be reasonable, and it has the characteristics of high removal efficiency and wide application range.

The present invention is characterized in that the combined treatment process for high-concentration organic wastewater carries out phased removal of high-concentration organic substances based on the differences in biodegradability of organic substances in high-concentration organic wastewater, and most of the biodegradable organic substances in the wastewater are first passed through low The micro-aerobic bacterial treatment method of operating costs can be removed, so that the residual organic components in the first stage of the effluent are mainly refractory organic matter, and then appropriate chemical oxidation methods (such as ultrasonic method, ozone method, Fenton oxidation method) are used according to the characteristics of wastewater quality etc.) to improve the biodegradability of wastewater, and adopt the activated sludge method as a post-treatment to ensure the quality of effluent water, which saves the operating cost of chemical oxidation to the greatest extent, and meets the requirements of both cost and effect and wide adaptability in the treatment of high-concentration organic wastewater Require.

The present invention is also characterized in that the high-concentration organic wastewater combined treatment process adopts micro-aerobic bacteria treatment method as pretreatment, and under micro-aerobic conditions, the selective advantage of micro-aerobic bacteria is used to carry out TCA cycle and efficiently decompose The biodegradable organic matter in high-concentration organic wastewater has a complete and thorough metabolic process, and the BOD removal rate can reach more than 95%.

The object of the present invention is to provide a high-concentration organic wastewater treatment process with wide application range and high removal efficiency, so as to solve the shortcomings of the existing process. Compared with the prior art, the invention patent has the following advantages:

(1) The process design is reasonable and the operating cost is low: according to the difference in the biodegradability of organic matter in high-concentration organic wastewater, the staged removal of high-concentration organic matter is carried out, which minimizes the operating cost of chemical oxidation. At the same time, this process uses micro-aerobic bacteria method to fully remove biodegradable organic matter, which can completely remove biodegradable organic matter in high-concentration organic wastewater like aerobic treatment, and the cost of aeration is only 5% of aerobic conditions or so or even lower. The combined process meets the requirements of both cost and effect and low operating cost in the treatment of high-concentration organic wastewater.

(2) Wide application range: the present invention is applicable to different types of high-concentration organic wastewater including high oil, high sulfur and high ammonia.

(3) High removal rate of organic matters: The removal rate of COD after wastewater treatment by this process is as high as 99%.

(4) low sludge output: the present invention adopts the micro-aerobic bacteria method as pretreatment and can degrade most of the biodegradable substances in high-concentration organic wastewater, and the sludge amount produced at this stage accounts for the vast majority of the whole process. Lower than the aerobic treatment under the same conditions, close to the anaerobic treatment.

Description of drawings

Accompanying drawing has provided process flow chart of the present invention.

Among them, 1 micro-aerobic reactor 2 is sedimentation tank 3 is chemical oxidation tank (tower)

4 is the intermediate tank 5 is the activated sludge tank 6 is the secondary sedimentation tank

Detailed ways

The working principle and implementation mode of the present invention will be described in detail below in conjunction with the accompanying drawings

A high-concentration organic wastewater combined treatment process of the present invention fully combines the advantages of chemical and biological treatment, and strengthens the staged removal effect of high-concentration organic matter. As shown in Figure 1, the wastewater enters a micro-aerobic reactor, and the mixed liquid After sedimentation in the 2nd sedimentation tank, the supernatant enters the 3rd chemical oxidation tank (tower), and the oxidized mixture flows into the 4th intermediate tank, and the effluent from the intermediate tank enters the 5th activated sludge tank, and the mixed solution is settled in the 6th secondary sedimentation tank to remove suspended solids and then discharged up to standard , part of the sludge at the bottom of the secondary settling tank in 6 returns to the activated sludge tank in 5.

Example 1

A certain high-sulfur fermented industrial waste water, its water quality characteristics are as shown in table 1, the present invention inoculates micro-aerobic bacteria in the micro-aerobic reactor and carries out batch culture, when MLSS reaches 8g/L, directly pass into this undiluted The fermentation waste water starts to be treated continuously, the dissolved oxygen content in the reactor is controlled between 0-0.5 mg/L, and the hydraulic retention time is 3 days. 60-120 minutes, after ozone oxidation, the wastewater enters the activated sludge tank after passing through the intermediate tank. On the 12th day, 40% of the sludge was refluxed, and the effluent from the activated sludge tank was settled in the secondary settling tank to remove suspended solids and then discharged up to the standard. The water output indicators are shown in Table 1.

Table 1 The index values before and after a certain fermentation industrial wastewater is treated by the combined process of the present invention

COD(mg/L) BOD(mg/L) Reducing sugar (mg/L) TN(mg/L) TP (mg/L) before processing 71134 52090 66722 1386 223 after processing 100 20 5 50 12

Example 2

The water quality characteristics of a certain food processing wastewater are shown in Table 2. First, microaerobic bacteria were inoculated in a microaerobic reactor and cultured in batches. When the MLSS reached 4g/L, the undiluted fermentation wastewater was directly introduced into Continuous treatment, control the dissolved oxygen content in the reactor between 0-0.5mg/L, the hydraulic retention time is 3d, the supernatant after the mixed solution is precipitated in the sedimentation tank enters the Fenton reagent oxidation reactor, according to H ₂ O ₂ /COD ( Add Fe ²⁺ and H _{2 O 2 at a ratio of W/W)=4.0, Fe 2+ /H 2 O 2} ⁽ _{W /} W)=0.08, react for 130 minutes and enter the intermediate pool, and the water from the intermediate pool (pH 7.5) enters Activated sludge tank, the temperature of the reaction zone is normal temperature, the hydraulic retention time is 10h, the dissolved oxygen concentration is greater than 2mg/L, the sludge concentration is 3g/L, the sludge residence time is 10d, the sludge is refluxed at 20%, and the effluent of the activated sludge tank is passed through two The sedimentation tank removes suspended solids and discharges up to the standard. The water output indicators are shown in Table 2.

Table 2 The index value before and after a certain food processing wastewater is treated by the combined process of the present invention

COD(mg/L) BOD(mg/L) Oil (mg/L) TN(mg/L) TP (mg/L) before processing 8659 3651 8.8 twenty four 18 after processing 50 12 0 2 1

Claims (1)

1. combined treatment process for high-concentration organic waste water, it is characterized in that: this technology is composed in series by micro-aerobic bacteria facture, chemical oxidization method, activated sludge process, the stage that it carries out high-enriched organics based on organic biodegradability difference in the high concentrated organic wastewater is removed, adopt the micro-aerobic bacteria facture to remove biodegradable organic earlier, improve the biodegradability of waste water subsequently by chemical oxidization method, adopt activated sludge process to ensure effluent quality at last as aftertreatment.