CN106542630B - PACT (Picture archiving and communication technology) process for reducing sludge discharge and recycling activated carbon - Google Patents
PACT (Picture archiving and communication technology) process for reducing sludge discharge and recycling activated carbon Download PDFInfo
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Abstract
The invention relates to the field of wastewater treatment, and discloses a PACT (Picture archiving and communication technology) process for reducing sludge discharge and recycling activated carbon, which comprises the following steps: (1) carrying out aeration treatment on the wastewater under the combined action of activated carbon and microorganisms; (2) carrying out precipitation separation on the effluent after aeration treatment to obtain supernatant and bottom sludge, discharging the supernatant as treated effluent, and refluxing part of the bottom sludge to the step (1); (3) and (4) carrying out sludge reduction and activated carbon recovery treatment on the excess sludge. The PACT process for reducing sludge discharge and recycling activated carbon integrates reduction treatment of residual activated sludge and recycling of activated carbon on the basis of the traditional PACT process, so that the process has the advantages of low operation cost, greatly reduced sludge external discharge, more flexible operation and the like.
Description
Technical Field
The invention relates to the field of wastewater treatment, in particular to a PACT (Picture archiving and communication technology) process for greatly reducing sludge discharge and recycling activated carbon.
Background
An Activated sludge-Powdered Activated Carbon process (namely, a Powdered Activated Carbon treatment process, which is abbreviated as PACT process) is an improved process of an Activated sludge method, and the process increases the removal of pollutants by adding Powdered Activated Carbon into a biochemical aeration tank and utilizing the combined action of the Powdered Activated Carbon and microorganisms in the Activated sludge. The PACT process is generally believed to have the following advantages: (1) the removal effect of the refractory organic matters is improved; (2) the capability of resisting poison impact of the system is improved; (3) the decoloring effect of the system is improved; (4) the settling and dewatering performance of the sludge is improved; (5) improving the nitration reaction efficiency; (6) the hydraulic retention time of the system is shortened; (7) the foam generation amount of the aeration tank is reduced; (8) and the running stability of the system is improved.
The price of the activated carbon is high, so that the operation cost of the PACT process is high, and the activated carbon becomes an important factor influencing the popularization and application of the PACT process. The running cost of the PACT process can be reduced by regenerating and recycling the activated carbon in the residual activated sludge of the PACT process. At present, a plurality of PACT technologies and related patent technologies and literature reports on the regeneration of activated carbon can be found. For example:
CN102616922A provides a novel PACT process for treating difficultly biodegradable wastewater by using renewable and recyclable powdered activated carbon, which comprises the following steps: 1) pumping out the powdered activated carbon and the biological activated sludge precipitated in the secondary sedimentation tank; 2) dehydrating the powdered activated carbon and the biological activated sludge extracted in the step 1); 3) drying, dry distilling and activating the dehydrated powdered activated carbon and the biological activated sludge obtained in the step 2) in sequence to decompose and volatilize organic matters adsorbed by the powdered activated carbon, and pyrolyzing the biological activated sludge into activated carbon; 4) grinding the product obtained in the step 3) into powder, and putting the powder into a biochemical pool as regenerated powder activated carbon for use.
CN101553435A proposes a method and apparatus for treating wastewater. The wastewater treatment system includes a bioreactor containing activated carbon and a first biological population, and may further include a membrane bioreactor and/or a wet oxidation unit. The invention is actually a combined process combining the PACT process and wet air oxidation regeneration of activated carbon.
CN1493535A proposes a method for preparing activated peat: the activated sludge is treated at a high temperature of 200-700 ℃ to obtain activated sludge carbon. The activated sludge is the activated sludge produced in the process of treating domestic sewage or industrial wastewater by microorganisms in order to reach the discharge standard, and the main components of the activated sludge are microorganisms and metabolic products thereof.
However, the existing activated carbon recycling technology has the problems of complex operation and high cost, and is not beneficial to effectively reducing the running cost of the PACT process.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a PACT process which is simple and convenient to operate, has low cost, reduces sludge discharge and recycles activated carbon.
In order to achieve the above objects, the present invention provides a PACT process for reducing sludge discharge and recycling activated carbon, the process comprising:
(1) carrying out aeration treatment on the wastewater under the combined action of activated carbon and microorganisms;
(2) carrying out precipitation separation on the effluent after aeration treatment to obtain supernatant and bottom sludge, discharging the supernatant as treated effluent, and refluxing part of the bottom sludge to the step (1);
(3) and (4) carrying out sludge reduction and activated carbon recovery treatment on the excess sludge.
Preferably, the method for sludge reduction and activated carbon recovery treatment comprises a thermal digestion method; more preferably, the conditions of the thermal digestion solution include: the temperature is 120-220 ℃, and the more preferable temperature is 150-200 ℃; the operation pressure is 2-16atm, and the preferable pressure is 6-15 atm; the reaction time is 0.5 to 4 hours, and more preferably 1 to 2.5 hours.
Preferably, the excess sludge is concentrated before being subjected to sludge reduction and activated carbon recovery treatment.
Preferably, the water content of the concentrated sludge is 96 to 99 wt%, more preferably 97.5 to 98.5 wt%.
Preferably, the concentrated clear solution is refluxed to step (1).
Preferably, at least 60% of the product after the sludge reduction and activated carbon recovery treatment is returned to the step (1), more preferably 70 to 90% of the product after the sludge reduction and activated carbon recovery treatment is returned to the step (1), the remaining part is precipitated and separated to obtain a clear liquid and a residual sludge, and the clear liquid is returned to the step (1) to discharge the residual sludge.
Preferably, in the step (1), the adding amount of the activated carbon is 10-300mg/L, more preferably 10-50mg/L, relative to the wastewater.
According to the PACT process for reducing sludge discharge and recycling activated carbon, the reduction treatment of the residual activated sludge and the recycling of the activated carbon are integrated on the basis of the traditional PACT process, the adding amount of the fresh powdered activated carbon is greatly reduced, the operation of the activated carbon recycling process is simple and convenient, the condition is mild, and the cost is greatly lower than that of the added fresh activated carbon, so that the operation cost of the PACT process is effectively reduced; almost all organic components in the residual sludge are converted into water-soluble low-molecular organic matters in the reduction treatment and enter the PACT unit again, so that the discharge of the sludge is greatly reduced, and the operation difficulty and the treatment cost of the subsequent sludge treatment are saved; the discharge of the excess sludge and the discharge of the residual activated carbon in the combined process are independent, so that the sludge age of the activated sludge and the retention time of the activated carbon in the aeration treatment are independent, the retention time of the activated carbon is further prolonged on the premise of reasonably controlling the sludge age, the concentration of the activated carbon in the aeration tank is flexibly controlled, and the overall treatment effect is improved.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
FIG. 1 is a process flow diagram of the PACT process of the present invention for reducing sludge discharge and recycling activated carbon.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The invention provides a PACT process for reducing sludge discharge and recycling activated carbon, which comprises the following steps:
(1) carrying out aeration treatment on the wastewater under the combined action of activated carbon and microorganisms;
(2) carrying out precipitation separation on the effluent after aeration treatment to obtain supernatant and bottom sludge, discharging the supernatant as treated effluent, and refluxing part of the bottom sludge to the step (1);
(3) and (4) carrying out sludge reduction and activated carbon recovery treatment on the excess sludge.
The PACT Process refers to an Activated sludge-Powdered Activated carbon Process (Powdered Activated carbon treatment Process), is an improved Process of an Activated sludge method, and adds Powdered Activated carbon into a biochemical aeration tank, so that the removal of pollutants is increased by utilizing the combined action of the Powdered Activated carbon and microorganisms in the Activated sludge. As shown in FIG. 1, the PACT process for reducing sludge discharge and recycling activated carbon of the present invention is a combined process combining conventional PACT process with excess sludge reduction and activated carbon recycling. Thus, the process of the present invention includes two process units, biochemical (conventional PACT unit) and abatement recovery.
Step (1) and step (2) of the process of the present invention are conventional PACT processes, constituting a biochemical unit. The invention aims to carry out sludge reduction and activated carbon recovery treatment on excess sludge so as to simply, conveniently and effectively reduce the cost of the PACT process, so that the aeration treatment in the step (1) and the precipitation separation in the step (2) have no special requirements and can be carried out by adopting a conventional method in the field.
The aeration treatment in the step (1) is generally carried out in an aeration tank, as shown in fig. 1, aeration oxygen supply equipment is generally arranged at the bottom of the aeration tank, wastewater enters the aeration tank, powdered activated carbon is added into the aeration tank, the wastewater is aerated in the aeration tank under the combined action of microorganisms and the activated carbon, and the microorganisms and the activated carbon in the aeration tank play a role in removing pollution together. It will be understood by those skilled in the art that the microorganisms are those produced in the activated sludge of wastewater. In the present invention, there is no particular requirement for the hydraulic retention time of the aeration tank, and the conventional arrangement in the art may be adopted, for example, the hydraulic retention time of the aeration tank may be 2 to 50 hours, preferably 8 to 30 hours.
The sedimentation separation in step (2) is generally carried out in a secondary sedimentation tank, as shown in fig. 1, the effluent of the aeration tank enters the secondary sedimentation tank for sedimentation separation, the supernatant is discharged out of the system as the treated effluent, a part of the sludge at the bottom returns to the aeration tank, and the rest is the residual sludge. In the invention, the hydraulic retention time of the secondary sedimentation tank has no special requirement, and the conventional setting in the field can be adopted, for example, the hydraulic retention time of the secondary sedimentation tank can be 45-240min, and preferably 80-120 min. There is no particular requirement for the reflux ratio of the bottom sludge, and the settings conventional in the art may be adopted, for example, the reflux ratio may be 10 to 300%, preferably 20 to 100%.
In the present invention, the method for sludge reduction and activated carbon recovery treatment in step (3) preferably includes a thermal digestion method. The conditions of the thermal digestion process preferably include: the temperature is 120-220 ℃, and the temperature is more preferably 150-200 ℃; the operating pressure is 2-16atm, more preferably 6-15 atm; the reaction time is 0.5 to 4 hours, more preferably 1 to 2.5 hours. In the above preferred case, sludge reduction and activated carbon recovery can be performed more favorably.
In the present invention, the sludge reduction and activated carbon recovery treatment may be performed in a reduction reactor.
In the present invention, since the excess sludge still contains a large amount of water, in order to achieve better sludge reduction and activated carbon recovery, it is preferable that the excess sludge is subjected to a sludge concentration treatment before the sludge reduction and activated carbon recovery treatment, as shown in fig. 1.
In the present invention, there is no particular requirement for the method of sludge concentration, and various methods commonly used in the art can be adopted. The water content of the concentrated sludge is preferably 96 to 99% by weight, more preferably 97.5 to 98.5% by weight.
In the present invention, in order to further reduce the process cost and better treat the wastewater, it is preferable to return the concentrated clear solution to step (1), i.e., to the aeration tank, as shown in fig. 1.
In the present invention, in order to achieve a better sludge reduction and activated carbon recovery, it is preferable to return at least 60% of the products after the sludge reduction and activated carbon recovery treatment to step (1), and it is more preferable to return 70 to 90% of the products after the sludge reduction and activated carbon recovery treatment to step (1), that is, to the aeration tank, as shown in fig. 1.
The rest is subjected to precipitation separation, which can be carried out in a separation tank to obtain clear liquid and residual sludge, and in order to further reduce the process cost and better treat the wastewater, the clear liquid is preferably returned to the step (1), namely to an aeration tank, and the residual sludge is discharged out of the system as shown in figure 1.
In the invention, no special requirement is required for the hydraulic retention time of the sedimentation separation in the separation tank, and the value can be taken according to the design standard of a common sedimentation tank, for example, the hydraulic retention time of the separation tank can be 45-240min, preferably 80-120 min.
In the process, due to the adoption of sludge reduction and activated carbon recovery treatment, most of activated carbon in the activated sludge can be recycled, so that the adding amount of fresh powdered activated carbon of a system can be greatly saved, in the step (1) of the invention, the adding amount of the activated carbon is preferably 10-300mg/L and more preferably 10-50mg/L relative to the wastewater, the wastewater refers to the system inlet water, and the adding amount of the activated carbon refers to the adding amount of the fresh powdered activated carbon, as shown in figure 1, i.e. relative to the system inlet water, the adding amount of the fresh powdered activated carbon is preferably 10-300mg/L and more preferably 10-50 mg/L.
In the present invention, as shown in FIG. 1, a biochemical unit is constituted by aeration treatment in an aeration tank and precipitation separation in a secondary sedimentation tank, and a reduction recovery unit is constituted by sludge concentration and reduction reaction of excess sludge and precipitation separation in a separation tank.
In summary, according to a preferred embodiment of the present invention, the process of the present invention preferably comprises: the wastewater to be treated is treated according to the process flow shown in figure 1. Aerating the wastewater to be treated in an aeration tank of a biochemical unit under the combined action of activated carbon and microorganisms, wherein the adding amount of fresh powdered activated carbon in the aeration tank is 10-50mg/L and the hydraulic retention time of the aeration tank is 8-30h relative to the system water inlet; the effluent after aeration treatment in the aeration tank enters a secondary sedimentation tank for sedimentation separation, the hydraulic retention time of the secondary sedimentation tank is 80-120min, supernatant and bottom sludge are obtained, the supernatant is taken as treated effluent and discharged out of the system, the bottom sludge partially flows back to the aeration tank, and the sludge reflux ratio of the secondary sedimentation tank is 20-100%; the excess sludge enters a decrement recovery unit, sludge concentration is firstly carried out until the water content is 97.5-98.5 wt%, and concentrated clear liquid flows back to an aeration tank; the concentrated sludge enters a decrement reactor to carry out sludge decrement and activated carbon recovery treatment by a thermal digestion method, the reaction temperature of the thermal digestion decrement operation is 150-200 ℃, the operation pressure is 6-15atm, and the reaction time is 1-2.5 h; 70-90% of the discharged material of the decrement reactor returns to the aeration tank, the rest discharged material enters a separation tank for precipitation separation, the hydraulic retention time of the separation tank is 80-120min, clear liquid and residual sludge are obtained, the clear liquid returns to the aeration tank, and the residual sludge is discharged out of the system.
Examples
The following examples further illustrate the invention but are not intended to limit the invention thereto.
In the following examples and comparative examples:
determination of COD: adopting a dichromate method (GB 11914-89);
measurement of BOD: measuring by using a BOD (biochemical oxygen demand) measuring instrument of Germany WTW company;
and (3) measuring ammonia nitrogen: adopting a Nas colorimetric method (GB 7479-87);
measurement of suspended matter: adopting a gravimetric method (GB 11901-89);
and (3) determination of oil content: adopts a method for measuring the oil content in the produced water of an oil field (SY/T0530-2011).
Example 1
This example illustrates the PACT process of the present invention for reducing sludge discharge and recycling activated carbon.
Basic conditions of wastewater to be treated: the waste water is the waste water produced by a certain oil refining enterprise, the COD is 550-650mg/L, the BOD is 230-350mg/L, the ammonia nitrogen is 25-35mg/L, the oil content is 16-32mg/L, and the suspended matter content is 100-200 mg/L.
The wastewater to be treated is treated according to the process flow shown in figure 1. Aerating the wastewater to be treated in an aeration tank of a biochemical unit under the combined action of activated carbon and microorganisms, wherein the adding amount of fresh powdered activated carbon in the aeration tank is 40mg/L relative to the system water inlet, the hydraulic retention time of the aeration tank is 12h, and the water temperature of the aeration tank is 20-25 ℃; the effluent after aeration treatment in the aeration tank enters a secondary sedimentation tank for sedimentation separation, the hydraulic retention time of the secondary sedimentation tank is 100min, supernatant and bottom sludge are obtained, the supernatant is discharged out of the system as treated effluent, part of the bottom sludge flows back to the aeration tank, and the reflux ratio of the sludge in the secondary sedimentation tank is 40%; the excess sludge enters a decrement recovery unit, sludge concentration is firstly carried out until the water content is 98 weight percent, and concentrated clear liquid flows back to an aeration tank; the concentrated sludge enters a decrement reactor to carry out sludge decrement and activated carbon recovery treatment by a thermal digestion method, the reaction temperature of the thermal digestion decrement operation is 180 ℃, the operation pressure is 10atm, and the reaction time is 2 h; and returning 85% of the discharged material of the decrement reactor to the aeration tank, and allowing 15% of the discharged material to enter a separation tank for precipitation separation, wherein the hydraulic retention time of the separation tank is 90min, clear liquid and residual sludge are obtained, the clear liquid is returned to the aeration tank, and the residual sludge is discharged out of the system.
COD of treated effluent was determined after 20 days of stable operation<30mg/L ammonia nitrogen<2mg/L, oil content<2mg/L, suspended matter content<30 mg/L. The amount of discharged residual sludge was 2L/m relative to the system feed water in terms of the water content of the discharged residual sludge of 98 wt%3And (4) waste water.
Example 2
This example illustrates the PACT process of the present invention for reducing sludge discharge and recycling activated carbon.
Basic conditions of wastewater to be treated: the waste water is the waste water produced by oil refining enterprises, the COD is 280-400mg/L, the BOD is 130-220mg/L, the ammonia nitrogen is 20-30mg/L, the oil content is 15-25mg/L, and the suspended matter content is 100-150 mg/L.
The wastewater to be treated is treated according to the process flow shown in figure 1. Aerating the wastewater to be treated in an aeration tank of a biochemical unit under the combined action of activated carbon and microorganisms, wherein the adding amount of fresh powdered activated carbon in the aeration tank is 30mg/L relative to the system water inlet, the hydraulic retention time of the aeration tank is 8h, and the water temperature of the aeration tank is 20-25 ℃; the effluent after aeration treatment in the aeration tank enters a secondary sedimentation tank for sedimentation separation, the hydraulic retention time of the secondary sedimentation tank is 80min, supernatant and bottom sludge are obtained, the supernatant is discharged out of the system as treated effluent, part of the bottom sludge flows back to the aeration tank, and the reflux ratio of the sludge in the secondary sedimentation tank is 20%; the excess sludge enters a decrement recovery unit, sludge concentration is firstly carried out until the water content is 97.5 weight percent, and concentrated clear liquid flows back to an aeration tank; the concentrated sludge enters a reduction reactor to carry out sludge reduction and activated carbon recovery treatment by a thermal digestion method, the reaction temperature of the thermal digestion reduction operation is 200 ℃, the operation pressure is 15atm, and the reaction time is 1 h; returning 80% of the discharged material of the decrement reactor to the aeration tank, allowing 20% of the discharged material to enter a separation tank for precipitation separation, allowing the hydraulic retention time of the separation tank to be 80min to obtain clear liquid and residual sludge, returning the clear liquid to the aeration tank, and discharging the residual sludge out of the system.
COD of treated effluent was determined after 20 days of stable operation<30mg/L ammonia nitrogen<2mg/L, oil content<2mg/L, suspended matter content<40 mg/L. The amount of discharged residual sludge was 1.5L/m relative to the system feed water in terms of the water content of the discharged residual sludge of 98 wt%3And (4) waste water.
Example 3
This example illustrates the PACT process of the present invention for reducing sludge discharge and recycling activated carbon.
Basic conditions of wastewater to be treated: the waste water is the waste water produced by a chemical industry enterprise, the COD is 1200-1600mg/L, the BOD is 380-680mg/L, the ammonia nitrogen is 32-42mg/L, the oil content is 18-35mg/L, and the suspended matter content is 150-300 mg/L.
The wastewater to be treated is treated according to the process flow shown in figure 1. Aerating the wastewater to be treated in an aeration tank of a biochemical unit under the combined action of activated carbon and microorganisms, wherein the adding amount of fresh powdered activated carbon in the aeration tank is 50mg/L relative to the system water inlet, the hydraulic retention time of the aeration tank is 30h, and the water temperature of the aeration tank is 20-25 ℃; the effluent after aeration treatment in the aeration tank enters a secondary sedimentation tank for sedimentation separation, the hydraulic retention time of the secondary sedimentation tank is 120min, supernatant and bottom sludge are obtained, the supernatant is discharged out of the system as treated effluent, part of the bottom sludge flows back to the aeration tank, and the reflux ratio of the sludge in the secondary sedimentation tank is 50%; the excess sludge enters a decrement recovery unit, sludge concentration is firstly carried out until the water content is 98.5 weight percent, and concentrated clear liquid flows back to an aeration tank; the concentrated sludge enters a decrement reactor to carry out sludge decrement and activated carbon recovery treatment by a thermal digestion method, the reaction temperature of the thermal digestion decrement operation is 180 ℃, the operation pressure is 10atm, and the reaction time is 2 h; 70% of the discharged material of the decrement reactor returns to the aeration tank, 30% of the discharged material enters the separation tank for precipitation separation, the hydraulic retention time of the separation tank is 100min, clear liquid and residual sludge are obtained, the clear liquid returns to the aeration tank, and the residual sludge is discharged out of the system.
COD of treated effluent was determined after 20 days of stable operation<60mg/L、Ammonia nitrogen<15mg/L, oil content<5mg/L, suspended matter content<50 mg/L. The amount of discharged residual sludge was 5L/m relative to the system feed water in terms of the water content of the discharged residual sludge of 98 wt%3And (4) waste water.
Example 4
This example illustrates the PACT process of the present invention for reducing sludge discharge and recycling activated carbon.
Basic conditions of wastewater to be treated: the waste water is the waste water produced by a chemical industry enterprise, the COD is 900-1100mg/L, the BOD is 280-520mg/L, the ammonia nitrogen is 20-35mg/L, the oil content is 15-30mg/L, and the suspended matter content is 100-200 mg/L.
The wastewater to be treated is treated according to the process flow shown in figure 1. Aerating the wastewater to be treated in an aeration tank of a biochemical unit under the combined action of activated carbon and microorganisms, wherein the adding amount of fresh powdered activated carbon in the aeration tank is 10mg/L relative to the system water inlet, the hydraulic retention time of the aeration tank is 24h, and the water temperature of the aeration tank is 20-25 ℃; the effluent after aeration treatment in the aeration tank enters a secondary sedimentation tank for sedimentation separation, the hydraulic retention time of the secondary sedimentation tank is 90min, supernatant and bottom sludge are obtained, the supernatant is discharged out of the system as treated effluent, part of the bottom sludge flows back to the aeration tank, and the reflux ratio of the sludge in the secondary sedimentation tank is 100%; the excess sludge enters a decrement recovery unit, sludge concentration is firstly carried out until the water content is 98 weight percent, and concentrated clear liquid flows back to an aeration tank; the concentrated sludge enters a decrement reactor to carry out sludge decrement and activated carbon recovery treatment by a thermal digestion method, the reaction temperature of the thermal digestion decrement operation is 150 ℃, the operation pressure is 6atm, and the reaction time is 2.5 h; returning 90% of the discharged material of the decrement reactor to the aeration tank, and allowing 10% of the discharged material to enter a separation tank for precipitation separation, wherein the hydraulic retention time of the separation tank is 120min, clear liquid and residual sludge are obtained, the clear liquid is returned to the aeration tank, and the residual sludge is discharged out of the system.
COD of treated effluent was determined after 20 days of stable operation<50mg/L ammonia nitrogen<5mg/L, oil content<3mg/L, suspended matter content<40 mg/L. The amount of discharged residual sludge was 4L/m relative to the system feed water in terms of the water content of the discharged residual sludge of 98 wt%3And (4) waste water.
Comparative example 1
Basic conditions of wastewater to be treated: the same as in example 1.
The wastewater treatment was carried out according to the procedure of example 1, except that the excess sludge in the secondary sedimentation tank was directly discharged to the outside, and the amount of fresh powdered activated carbon added in the aeration tank was 200 mg/L.
COD of treated effluent was determined after 20 days of stable operation<40mg/L, ammonia nitrogen<3mg/L, oil content<2mg/L, suspended matter content<35 mg/L. The amount of sludge discharged was 6L/m relative to the system feed water in terms of the water content of the discharged sludge of 98 wt%3And (4) waste water.
Comparing the comparative example 1 with the example 1, it can be seen that the excess sludge in the secondary sedimentation tank is directly discharged, even if the adding amount of the fresh powdered activated carbon is greatly increased, the wastewater treatment effect is not much different from that of the example 1, and the sludge discharge amount is much higher than that of the example 1.
Comparative example 2
Basic conditions of wastewater to be treated: the same as in example 1.
The wastewater treatment was carried out according to the process of example 1, except that the excess sludge in the secondary sedimentation tank was directly discharged, and activated carbon was not added in the aeration tank, and the hydraulic retention time in the aeration tank was 18 hours.
COD of treated effluent was determined after 20 days of stable operation<60mg/L ammonia nitrogen<10mg/L, oil content<5mg/L, suspended matter content<70 mg/L. The amount of sludge discharged was 5L/m relative to the system feed water in terms of the water content of the discharged sludge of 98 wt%3And (4) waste water.
Comparing the comparative example 2 with the example 1, it can be seen that the excess sludge in the secondary sedimentation tank is directly discharged outside, and no activated carbon is added in the aeration tank, even if the hydraulic retention time is improved by 50%, the treatment effect is worse than that of the example 1, and the sludge discharge amount is much higher than that of the example 1.
Comparing the example 1 with the comparative example 1 and the comparative example 2 respectively, the process of the invention can treat the wastewater well, greatly reduce the external discharge of the sludge, recycle the activated carbon and reduce the process cost. Compared with the existing process for recycling the activated carbon, the process provided by the invention is simple and convenient to operate, mild in condition and capable of effectively reducing the operation cost of the PACT process.
According to the PACT process for reducing sludge discharge and recycling activated carbon, the reduction treatment of the residual activated sludge and the recycling of the activated carbon are integrated on the basis of the traditional PACT process, the adding amount of the fresh powdered activated carbon is greatly reduced, the operation of the activated carbon recycling process is simple and convenient, the condition is mild, and the cost is greatly lower than that of the added fresh activated carbon, so that the operation cost of the PACT process is effectively reduced; almost all organic components in the residual sludge are converted into water-soluble low-molecular organic matters in the reduction treatment and enter the PACT unit again, so that the discharge of the sludge is greatly reduced, and the operation difficulty and the treatment cost of the subsequent sludge treatment are saved; the discharge of the excess sludge and the discharge of the residual activated carbon in the combined process are independent, so that the sludge age of the activated sludge and the retention time of the activated carbon in the aeration treatment are independent, the retention time of the activated carbon is further prolonged on the premise of reasonably controlling the sludge age, the concentration of the activated carbon in the aeration tank is flexibly controlled, and the overall treatment effect is improved.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (10)
1. A PACT process for reducing sludge discharge and recycling activated carbon, which is characterized by comprising a biochemical unit consisting of a step (1) and a step (2) and a decrement recycling unit consisting of a step (3):
(1) carrying out aeration treatment on the wastewater under the combined action of activated carbon and microorganisms;
(2) precipitating and separating the effluent after aeration treatment in a secondary sedimentation tank to obtain supernatant and bottom sludge, discharging the supernatant as treated effluent, and refluxing part of the bottom sludge to the step (1), wherein the reflux ratio of the bottom sludge is 10-100%;
(3) performing sludge reduction and activated carbon recovery treatment on the excess sludge by a thermal digestion method; the conditions of the thermal digestion process include: the temperature is 120-220 ℃; the operation pressure is 2-16 atm; the reaction time is 0.5-4 h;
wherein the excess sludge is subjected to sludge concentration before sludge reduction and activated carbon recovery treatment, the water content of the concentrated sludge is 96-99 wt%, and clear liquid obtained by concentration is refluxed to the step (1);
returning at least 60% of the products after the sludge reduction and activated carbon recovery treatment to the step (1), precipitating and separating the rest in a separation tank to obtain clear liquid and residual sludge, returning the clear liquid to the step (1), and discharging the residual sludge.
2. The process according to claim 1, wherein the conditions of the thermal digestion process comprise: the temperature is 150-200 ℃; the operating pressure is 6-15 atm; the reaction time is 1-2.5 h.
3. The process as claimed in claim 1, wherein the water content of the concentrated sludge is 97.5-98.5 wt%.
4. The process according to claim 1, wherein 70-90% of the product after the sludge reduction and activated carbon recovery treatment is returned to the step (1).
5. The process according to claim 1, wherein in the step (1), the amount of the activated carbon added is 10 to 300mg/L relative to the wastewater.
6. The process of claim 5, wherein the amount of activated carbon added is 10-50 mg/L.
7. The process of claim 1, wherein the reflux ratio of the bottom sludge is 20-100%.
8. The process as claimed in claim 1, wherein the aeration treatment is carried out in an aeration tank, the hydraulic retention time in the aeration tank is 2-50h, and the water temperature in the aeration tank is 20-25 ℃.
9. The process according to claim 1, wherein the hydraulic retention time in the secondary sedimentation tank and the separation tank is each independently 45-240 min.
10. The process of claim 1, wherein the sludge reduction and activated carbon recovery process is performed in a reduction reactor.
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| CN201510614086.1A CN106542630B (en) | 2015-09-23 | 2015-09-23 | PACT (Picture archiving and communication technology) process for reducing sludge discharge and recycling activated carbon |
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| CN107522353A (en) * | 2017-08-17 | 2017-12-29 | 河海大学 | A kind of activated sludge membrane capacitance Integrated Processing Unit and technique that high-salt wastewater is handled using Facultative Halophiles |
| CN109626756A (en) * | 2019-01-29 | 2019-04-16 | 中环清源(北京)科技有限公司 | A kind of method of PACT-MBR coupling technique treatment of laboratory waste water |
| CN109650559A (en) * | 2019-02-22 | 2019-04-19 | 江苏同瑞环保有限公司 | A kind of modified form charcoal processing system technique |
| CN114291914A (en) * | 2020-12-23 | 2022-04-08 | 吴植仁 | Novel sewage treatment process using self-produced peat as adsorbent and method for measuring carbon-water ratio |
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| CN102616922A (en) * | 2012-04-23 | 2012-08-01 | 重庆康达环保产业（集团）有限公司 | PACT (Production Analysis Control Technique) novel process for treating non-biodegradable waste water by using circularly-reproducible powdered activated carbon |
| CN102964021A (en) * | 2011-09-01 | 2013-03-13 | 中国石油化工股份有限公司 | Method for processing organic waste water |
| CN103086503A (en) * | 2013-02-26 | 2013-05-08 | 广东新大禹环境工程有限公司 | PACT (powdered activated carbon treatment) process and device, and activated carbon-microbial zoogloea culture method using same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102964021A (en) * | 2011-09-01 | 2013-03-13 | 中国石油化工股份有限公司 | Method for processing organic waste water |
| CN102616922A (en) * | 2012-04-23 | 2012-08-01 | 重庆康达环保产业（集团）有限公司 | PACT (Production Analysis Control Technique) novel process for treating non-biodegradable waste water by using circularly-reproducible powdered activated carbon |
| CN103086503A (en) * | 2013-02-26 | 2013-05-08 | 广东新大禹环境工程有限公司 | PACT (powdered activated carbon treatment) process and device, and activated carbon-microbial zoogloea culture method using same |
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