Semi-coke wastewater biochemical treatment system and treatment process thereof

Abstract

The invention discloses a semi-coke wastewater biochemical treatment system and a treatment process thereof, and relates to the technical field of semi-coke wastewater biochemical treatment, the semi-coke wastewater biochemical treatment system comprises a treatment system, the treatment system comprises an oil removal flotation module, an anaerobic module and a multi-stage anaerobic-aerobic module; the oil removal air floatation module comprises an oil separation tank, a buffer tank, an accident tank and an inert air floatation tank, and the oil separation tank, the buffer tank, the accident tank and the inert air floatation tank are connected with one another. Through combination of oil removal flotation, anaerobic treatment and multi-stage anaerobic-aerobic treatment, oil, phenols and other refractory organic matters in the wastewater can be effectively removed, and the biodegradability of the wastewater is remarkably improved. The oxidation problem of phenolic substances is avoided by adopting inert gas floatation, the toxicity of the wastewater is remarkably reduced by the composite anaerobic fluidized bed reactor, finally, organic pollutants are stably degraded by virtue of a multi-stage anaerobic-aerobic process, the concentration of the pollutants can be effectively reduced, the effluent quality is ensured to be stable and reach the standard, and the semi-coke wastewater treatment device is suitable for biochemical treatment of semi-coke wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of biochemical treatment of blue charcoal wastewater, and in particular to a blue charcoal wastewater biochemical treatment system and a treatment process thereof. Background Art

[0002] Semi-coke wastewater is low-grade coal medium-low temperature dry distillation wastewater, mainly produced in the wet quenching unit of semi-coke cooling and the residual circulating ammonia water unit of coal gas purification. Low-grade coal has a high volatile content. During the medium-low temperature dry distillation (500-650℃), a large amount of volatiles break bonds to form low-molecular organic matter and adhere to the semi-coke pores or leave the dry distillation furnace with coal gas. Sulfur and nitrogen react under reducing conditions to convert into inorganic pollutants such as H2S, NH3, cyanide and thiocyanate. Therefore, semi-coke wastewater has the characteristics of high oil dust, high ammonia nitrogen, high phenol and high COD, and its composition is complex and extremely difficult to treat.

[0003] The lignite industry started relatively late, and its current wastewater treatment process mainly refers to the wastewater treatment standards of the coking industry. However, there are certain differences between coking wastewater and lignite wastewater.

[0004] The semi-coke wastewater is pre-treated by tar, phenol, ammonia recovery and other facilities. It contains high COD, high ammonia nitrogen, BC ratio <0.3, and also contains phenol, cyanide, oil and other bio-inhibitory and bio-toxic substances.

[0005] The semi-coke wastewater pre-treated after phenol-ammonia recovery has the following characteristics:

[0006] ① The biochemical system has poor stability and the tail water COD is high; oil, phenol, ammonia, thiocyanate and sulfide influence and restrict each other during the utilization of microorganisms; the COD of organic wastewater from the medium-temperature gasification process is still high after complex biochemical treatment.

[0007] As mentioned above, we have designed a biochemical treatment system for lignite wastewater and its treatment process to solve the above problems. Summary of the invention

[0008] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a biochemical treatment system for blue carbon wastewater and a treatment process thereof.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A biochemical treatment system for semi-carbon wastewater, comprising a treatment system, wherein the treatment system comprises an oil removal flotation module, an anaerobic module and a multi-stage anaerobic-aerobic module;

[0011] The oil removal flotation module comprises an oil separator, a buffer tank, an accident tank and an inert gas flotation tank, wherein the oil separator, the buffer tank, the accident tank and the inert gas flotation tank are connected to each other, and the oil separator is provided with two outlets, one outlet is connected to the accident tank, and the other outlet is connected to the buffer tank;

[0012] The anaerobic module includes an anaerobic tank and a composite anaerobic fluidized bed reactor, the composite anaerobic fluidized bed reactor is connected to an anaerobic water inlet tank, the composite anaerobic fluidized bed reactor includes an inlet end and an outlet end in an external circulation form, and the outlet end of the composite anaerobic fluidized bed reactor is connected to a multi-stage anaerobic-aerobic module;

[0013] The multi-stage anaerobic-aerobic module comprises an improved AO unit, a middle sedimentation tank, a biologically enhanced AO unit, and a final sedimentation tank, wherein the improved AO unit, the middle sedimentation tank, the biologically enhanced AO unit, and the final sedimentation tank are connected in sequence, and the outlet end of the final sedimentation tank is connected to a biochemical effluent tank.

[0014] Preferably, the biochemical effluent pool is provided with two outlets, which are respectively connected to the biochemical effluent pipe and the quenching water pool.

[0015] Preferably, the inert gas flotation tank is filled with nitrogen.

[0016] A treatment process of a semi-carbon wastewater biochemical treatment system comprises the following working steps:

[0017] Step S1, grease trap pretreatment: the wastewater first passes through the grease trap to initially remove the floating oil therein, and then enters the inert flotation tank containing nitrogen for flotation oil removal treatment;

[0018] Step S2, using a composite anaerobic fluidized bed reactor for the wastewater output from step S1, using microbial extracellular enzymes to decompose macromolecular organic matter into small molecular organic matter, hydrolyzing long chains into short chains, branched chains into straight chains, and ring structures into straight chains or branched chains, so as to improve the biodegradability of the wastewater and remove a certain amount of COD, and then entering the multi-stage anaerobic-aerobic module;

[0019] Step S3, allowing the wastewater entering the multi-stage anaerobic-aerobic module to pass through the improved AO unit, the intermediate sedimentation tank, the bio-enhanced AO unit, and the final sedimentation tank in sequence;

[0020] First, the wastewater enters the improved AO pool. The characteristics of the improved AO pool are that it has the characteristics of large reflux ratio and low oxygen aeration, which can effectively enhance the biochemical impact resistance and reduce the impact of toxic substances in the incoming water. The wastewater after removing most of the COD and total nitrogen enters the intermediate sedimentation tank for mud and water separation. After the wastewater is precipitated, the secondary AO process further treats the wastewater. During the treatment, biological carriers are added in the bio-enhanced AO process for treatment, and then the wastewater enters the final sedimentation tank for treatment to achieve solid-liquid separation.

[0021] Preferably, the improved AO unit operation control conditions are:

[0022] Low dissolved oxygen: 0.3mg / L-0.35mg / L;

[0023] High sludge concentration 8000mg / L-8500mg / L.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: the blue carbon wastewater treatment system provided by the present invention can effectively remove oils, phenols and other difficult-to-degrade organic matter in wastewater through the combination of oil removal flotation, anaerobic treatment and multi-stage anaerobic-aerobic treatment, and significantly improve the biodegradability of wastewater. The use of inert gas flotation avoids the oxidation problem of phenolic substances, and the composite anaerobic fluidized bed reactor significantly reduces the toxicity of wastewater, and finally the organic pollutants are stably degraded through a multi-stage anaerobic-aerobic process. The system can effectively reduce the concentration of pollutants, ensure that the effluent water quality is stable and meets the standards, and is suitable for deep treatment of blue carbon wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention provides a process flow chart of a biochemical treatment system for blue carbon wastewater and its treatment process. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0027] Reference Figure 1 , a biochemical treatment system for blue carbon wastewater, comprising a treatment system, wherein the treatment system comprises an oil removal flotation module, an anaerobic module and a multi-stage anaerobic-aerobic module;

[0028] In this embodiment, the oil removal flotation module includes a grease trap, a buffer tank, an accident tank and an inert gas flotation tank. The inert gas flotation tank is filled with nitrogen. The grease trap, the buffer tank, the accident tank and the inert gas flotation tank are connected. The buffer tank is provided with two outlets, one outlet is connected to the accident tank, and the other outlet is connected to the anaerobic module.

[0029] The anaerobic module includes an anaerobic tank and a composite anaerobic fluidized bed reactor, the composite anaerobic fluidized bed reactor is connected to the anaerobic tank, the composite anaerobic fluidized bed reactor includes an inlet end and an outlet end in an external circulation form, and the outlet end of the composite anaerobic fluidized bed reactor is connected to the multi-stage anaerobic-aerobic module;

[0030] The multi-stage anaerobic-aerobic module comprises an improved AO unit, a middle sedimentation tank, a biologically enhanced AO unit, and a final sedimentation tank, wherein the improved AO unit, the middle sedimentation tank, the biologically enhanced AO unit, and the final sedimentation tank are connected in sequence, and the water outlet end of the final sedimentation tank is connected to a biochemical water outlet tank, and the biochemical water outlet tank is provided with two outlets, which are respectively connected to a biochemical water outlet pipe and a coke quenching water tank.

[0031] In the above embodiment,

[0032] A treatment process of a semi-carbon wastewater biochemical treatment system comprises the following working steps:

[0033] Step S1, after the semi-coke wastewater is recovered by phenol and ammonia, the oil content is as high as about 500 mg / L, and the wastewater is first pre-treated in a grease trap, wherein the wastewater first stays in a grease trap to initially remove the floating oil therein, and then enters an inert flotation tank containing nitrogen for flotation oil removal treatment;

[0034] If it enters the biochemical system directly without pretreatment, it will cause the following problems:

[0035] The floating oil layer on the water surface affects the transfer of oxygen and is not conducive to the progress of biochemical reactions.

[0036] Oil substances will adhere to and wrap the flocs, hindering the metabolic process and material exchange of the flocs, and may cause the sludge to become less active or even die.

[0037] The oil layer increases the demand for oxygen, which may cause a sharp drop in dissolved oxygen in the biochemical pool, impacting the stability of the entire biochemical system.

[0038] In the above-mentioned oil separation treatment, more specifically, the wastewater first passes through the oil separation tank to stay and initially remove the floating oil therein, and then enters the inert flotation tank from the oil separation tank. Conventional flotation treatment uses air as a foaming agent, which may cause phenolic pollutants to be oxidized into benzoquinone intermediates that are difficult to degrade.

[0039] This process uses inert gas (such as nitrogen) for flotation oil removal, avoiding the problem of air oxidation of phenolic substances.

[0040] At the same time, through the oil separator and flotation treatment, the floating oil on the surface of the wastewater is basically removed, creating favorable conditions for subsequent biochemical treatment.

[0041] Step S2, using a composite anaerobic fluidized bed reactor for the wastewater output from step S1, using microbial extracellular enzymes to decompose macromolecular organic matter into small molecular organic matter, hydrolyzing long chains into short chains, branched chains into straight chains, and ring structures into straight chains or branched chains, so as to improve the biodegradability of the wastewater and remove a certain amount of COD, and then entering the multi-stage anaerobic-aerobic module;

[0042] It should be noted that in the prior art, after the recovery and pretreatment of phenol and ammonia, the semi-coke wastewater still has a low biodegradability, usually manifested as a B / C ratio of <0.3. The organic matter in the wastewater is mainly polycyclic aromatic hydrocarbons and oil substances that are difficult to degrade, and contains biologically toxic phenols, cyanides, thiocyanides, etc.

[0043] The processing method in step S2 is:

[0044] A composite anaerobic fluidized bed reactor is used for treatment, which utilizes microbial extracellular enzymes to decompose macromolecular organic matter into small molecular organic matter, thereby improving the biodegradability of the wastewater.

[0045] External circulation: The reactor adopts external circulation, diluting the inlet water through the reactor effluent to reduce the toxicity of phenolic substances and cyanide in the wastewater to hydrolytic bacteria.

[0046] Degradation of organic matter: In the reactor, organic matter is degraded by hydrolytic bacteria into short-chain, branched or linear compounds, thereby improving the biodegradability of the wastewater and removing a certain amount of chemical oxygen demand (COD).

[0047] Step S3, allowing the wastewater entering the multi-stage anaerobic-aerobic module to pass through the improved AO unit, the intermediate sedimentation tank, the bio-enhanced AO unit, and the final sedimentation tank in sequence;

[0048] First, the wastewater enters the improved AO pool. The characteristics of the improved AO pool are that it has the characteristics of large reflux ratio and low oxygen aeration, which can effectively enhance the biochemical impact resistance and reduce the impact of toxic substances in the incoming water. The wastewater after removing most of the COD and total nitrogen enters the intermediate sedimentation tank for mud and water separation. After the wastewater is precipitated, the secondary AO process further treats the wastewater. During the treatment, biological carriers are added in the bio-enhanced AO process for treatment, and then the wastewater enters the final sedimentation tank for treatment to achieve solid-liquid separation.

[0049] It should be noted that the multi-stage anaerobic-aerobic unit in step S3 is the core biochemical unit for the treatment of lignite wastewater, which aims to further degrade COD and total nitrogen in the wastewater while removing residual refractory organic matter.

[0050] More specifically, in step S3:

[0051] During treatment, the operation control of the improved AO unit is: operating under conditions of low dissolved oxygen (about 0.3 mg / L) and high sludge concentration (about 8000 mg / L).

[0052] Large-ratio circulation dilution technology: The large-ratio circulation dilution technology can increase the total nitrogen removal rate by about 10%, while reducing the impact of toxic substances in the incoming water on the system and reducing the power consumption of the system.

[0053] Secondary sedimentation tank: The wastewater after improved AO enters the secondary sedimentation tank for mud-water separation and removal of most COD and total nitrogen.

[0054] Bio-augmented AO process: After the wastewater is precipitated, although most of the COD and total nitrogen have been removed, some COD and total nitrogen that are difficult to degrade still remain.

[0055] The wastewater is further treated by the bioaugmented AO process.

[0056] Bio-augmented AO: Adding biological carriers to the secondary AO process to improve the removal rate of poorly biodegradable organic compounds and total nitrogen.

[0057] Bioaugmented AO also has the function of improving color and enhancing sludge settling performance.

[0058] The adsorption balance function of activated carbon can improve the overall anti-shock load capacity of the system.

[0059] Final sedimentation tank: Finally, the wastewater is treated in the final sedimentation tank to achieve solid-liquid separation, and the effluent is stable and meets the standards.

[0060] The semi-coke wastewater treatment process of the present invention gradually removes oils, phenols, cyanides and other refractory organic matter in the wastewater through the synergistic effect of the oil removal flotation unit, the anaerobic unit and the multi-stage anaerobic-aerobic unit, and significantly improves the biodegradability of the wastewater. The process can effectively reduce the concentration of pollutants, ensure that the effluent water quality is stable and meets the standards, and is suitable for the deep treatment of semi-coke wastewater.

[0061] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A biochemical treatment system for blue carbon wastewater, comprising a treatment system, characterized in that: The treatment system includes an oil removal flotation module, an anaerobic module, and a multi-stage anaerobic-aerobic module; The oil removal flotation module comprises an oil separator, a buffer tank, an accident tank and an inert gas flotation tank, wherein the oil separator, the buffer tank, the accident tank and the inert gas flotation tank are connected to each other, and the oil separator is provided with two outlets, one outlet is connected to the accident tank, and the other outlet is connected to the buffer tank; The anaerobic module includes an anaerobic water inlet tank and a composite anaerobic fluidized bed reactor, the composite anaerobic fluidized bed reactor is connected to the anaerobic water inlet tank, the composite anaerobic fluidized bed reactor includes an inlet end and an outlet end in an external circulation form, and the outlet end of the composite anaerobic fluidized bed reactor is connected to the multi-stage anaerobic-aerobic module; The multi-stage anaerobic-aerobic module comprises an improved AO unit, a middle sedimentation tank, a biologically enhanced AO unit, and a final sedimentation tank, wherein the improved AO unit, the middle sedimentation tank, the biologically enhanced AO unit, and the final sedimentation tank are connected in sequence, and the outlet end of the final sedimentation tank is connected to a biochemical effluent tank.

2. A biochemical treatment system for blue carbon wastewater according to claim 1, characterized in that: The biochemical water outlet pool is provided with two outlets, and the two outlets are respectively connected to the biochemical water outlet pipe and the quenching water pool.

3. A biochemical treatment system for blue carbon wastewater according to claim 1, characterized in that: The inert gas flotation tank uses nitrogen as the pressurized dissolved gas.

4. A treatment process based on the biochemical treatment system of blue carbon wastewater according to claims 1-3, characterized in that: The following steps are included: Step S1, grease trap pretreatment: the wastewater first passes through the grease trap to initially remove the floating oil therein, then passes through the buffer tank for homogenization and equalization, and then enters the inert gas flotation tank using nitrogen as the pressurized dissolved gas for flotation oil removal treatment; Step S2, using a composite anaerobic fluidized bed reactor for the wastewater output from step S1, using microbial extracellular enzymes to decompose macromolecular organic matter into small molecular organic matter, hydrolyzing long chains into short chains, branched chains into straight chains, and ring structures into straight chains or branched chains, so as to improve the biodegradability of the wastewater and remove a certain amount of COD, and then entering the multi-stage anaerobic-aerobic module; Step S3, allowing the wastewater entering the multi-stage anaerobic-aerobic module to pass through the improved AO unit, the intermediate sedimentation tank, the bio-enhanced AO unit, and the final sedimentation tank in sequence; First, the wastewater enters the improved AO pool. The characteristics of the improved AO pool are that it has the characteristics of large reflux ratio and low oxygen aeration, which can effectively enhance the biochemical impact resistance and reduce the impact of toxic substances in the incoming water. The wastewater after removing most of the COD and total nitrogen enters the intermediate sedimentation tank for mud and water separation. After the wastewater is precipitated, the secondary AO process further treats the wastewater. During the treatment, biological carriers are added in the bio-enhanced AO process for treatment, and then the wastewater enters the final sedimentation tank for treatment to achieve solid-liquid separation.

5. The treatment process of a biochemical treatment system for blue carbon wastewater according to claim 4 is characterized in that: The improved AO unit operation control conditions are: Low dissolved oxygen: 0.3mg / L-0.35mg / L; High sludge concentration 8000mg / L-8500mg / L.

Images