KR101880619B1 - Method for treating wastewater from biogas plant using food waste - Google Patents

Abstract

The present invention relates to a method and a system for treating wastewater from food waste, which can improve treatment efficiency of wastewater generated during a food waste treating process by anaerobic digestion. According to the present invention, compared with a method for treating food waste which conventionally contains nitrogen and phosphorus at a high concentration, it is possible to treat anaerobic digestion sludge of the food waste and anaerobic digestion wastewater discharged after the anaerobic digestion with high efficiency.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and a system for treating wastewater generated in a food processing facility,

The present invention relates to a method and system for treating food waste wastewater, which can improve the treatment efficiency of wastewater generated during a food garbage disposal process by anaerobic digestion.

Currently, food waste (food waste) is processed through an anaerobic digestion process to produce methane gas, which is energy source.

Generally, the digested sludge generated after anaerobic digestion of food waste is separated into a solid dehydrated sludge cake and a liquid waste water (desalted liquid) after the dehydration process. The dehydrated sludge cake is dried or unloaded as it is, and the anaerobic digestion wastewater is discharged through a biological treatment process. However, since the anaerobic digestion wastewater of the food wastes contains nitrogen and phosphorus at a high concentration, it is difficult to satisfy the water quality required for the discharged water with high concentration of nitrogen and phosphorus only by the biological treatment process.

In order to remove nitrogen and phosphorus at high concentrations in the anaerobic digestion wastewater of the food wastes, the anaerobic digestion wastewater is treated with ammonia stripping to remove anaerobic digestion wastewater (SS, suspended solids), followed by biological treatment Has been developed.

FIG. 1 is a schematic diagram of a food waste disposal process according to the prior art, wherein a floating solid (SS) of anaerobic digestion wastewater of the food waste is removed, and a biological treatment is performed after pretreatment through an ammonia stripping process.

Referring to FIG. 1, the food waste treatment process includes an anaerobic digestion process; Digestion sludge dewatering process; A dehydrating sludge treatment process and a wastewater (desalination) treatment process.

The anaerobic digestion process may be carried out in a food waste disposal facility or a biogasification facility, where methane gas is produced by anaerobic digestion and the remaining digested sludge is transferred to a digester sludge storage for further processing.

Thereafter, the digested sludge is separated into a solid material as a dehydrated sludge and a waste water (desalination liquid) through a dehydration process.

The solid matter is discharged as it is or dried after it is dried.

The wastewater (desolvation solution) is discharged through a biological treatment process after a pretreatment process including ammonia stripping process after removing Suspended Solids (SS).

However, not only the ammonia stripping process requires elevating the pH to 11, but also difficulty in removing high concentration nitrogen and phosphorus in the wastewater of the food waste (ammonia stripping process) to suit the water quality conditions of the discharged water.

In addition, although the concept of dilution has been introduced, a linkage treatment method of transporting the waste water to a nearby sewage treatment plant has been attempted, but its application is limited depending on the surrounding location conditions of the food waste treatment facility.

Japanese Laid-Open Patent Publication No. 2003-334584 Korea Patent Publication No. 2013-0134149

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a treatment method capable of increasing the treatment efficiency of anaerobic digestion sludge of food waste containing high nitrogen and phosphorus concentration and anaerobic digestion wastewater discharged after anaerobic digestion .

According to an aspect of the present invention, there is provided an anaerobic digestion sludge digesting method, comprising: (A) an anaerobic digestion sludge reforming step for improving anaerobic digestion ability of an anaerobic digestion sludge;

(B) a dewatering step of subjecting the modified anaerobic digestion sludge to solid-liquid separation into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And

(C) a method for disposing of food wastes,

The anaerobic digester sludge reforming step

(a1) removing anaerobic digestion residual gas by stirring; And

(a2) a sludge stabilization step through aeration,

The desalination treatment step

(c1) removing the suspended solids (SS) in the desolvation solution;

(c2) biological treatment after removing the suspended solids;

(c3) separating the membrane through the separation membrane after the biological treatment;

(c4) adjusting the pH of the membrane-separated desalin solution to ammoniumate the ammonia in the desalin solution; And

(c5) heating and concentrating the desalted solution having the pH adjusted therein, and a method for treating garbage.

Another aspect of the present invention relates to a digestion sludge reforming tank for improving anaerobic digestion ability of anaerobic digestion sludge discharged from an anaerobic digestion tank;

A dehydrator for separating the anaerobically digested sludge modified in the digestion sludge reforming tank into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And

And a desorbing liquid treating apparatus for treating the desorbing liquid,

The desalination apparatus

A suspended solids removal tank for removing suspended solids (SS) in the desolvation solution;

A biological treatment tank for biological treatment of the desorbed liquid from which the suspended solids are removed;

A membrane separation tank for separating the biologically treated desolvation solution into a separation membrane;

An ammonium tank for ammoniumifying ammonia by adjusting the pH of the membrane-separated desalination liquid; And

The pH-adjusted desalted liquid And an evaporation concentrator for separating the concentrated water into condensed water and condensed water by evaporation.

In another aspect of the present invention, there is provided a method of treating food waste comprising an anaerobic digestion process,

(A) an anaerobic digestion sludge reforming step for improving the dehydration ability of the anaerobic digestion sludge;

(B) a dewatering step of subjecting the modified anaerobic digestion sludge to solid-liquid separation into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And

(C) the desalination treatment step,

The desalination treatment step

(c1) removing the suspended solids (SS) in the desolvation solution;

(c2) biological treatment after removing the suspended solids;

(c3) separating the membrane through the separation membrane after the biological treatment;

(c4) adjusting the pH of the membrane-separated desalin solution to ammoniumate the ammonia in the desalin solution; And

(c5) heating and concentrating the desalted solution having the pH adjusted therein by evaporation,

And the amount of the concentrated water to be recycled is adjusted according to the measurement value of TS (total solid), COD (chemical oxygen demand) or TN (total nitrogen) of the solid-liquid separated desalination liquid .

According to another aspect of the present invention, there is provided a digestion sludge reforming tank for anaerobic digestion sludge discharged from an anaerobic digestion tank,

A dehydrator for separating the anaerobically digested sludge modified in the digestion sludge reforming tank into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And

And a desorbing liquid treating apparatus for treating the desorbing liquid,

The desalination apparatus

A suspended solids removal tank for removing suspended solids (SS) in the desolvation solution;

A biological treatment tank for biological treatment of the desorbed liquid from which the suspended solids are removed;

A membrane separation tank for separating the biologically treated desolvation solution into a separation membrane;

An ammonium tank for ammoniumifying ammonia by adjusting the pH of the membrane-separated desalination liquid;

The pH-adjusted desalted liquid An evaporation concentrator for evaporating and concentrating the water into concentrated water and condensed water; And

And a control unit including the TS or the COD or TN measurement apparatus of the solid-liquid separated desalination liquid and the concentrated water.

According to the present invention, it is possible to treat anaerobic digestion sludge of food waste and anaerobic digestion wastewater discharged after anaerobic digestion with higher efficiency as compared with the conventional method of treating garbage containing nitrogen and phosphorus at high concentration.

FIG. 1 is a flowchart showing a process of treating garbage according to Comparative Example 1. FIG.
FIG. 2 is a flowchart showing a process of treating garbage according to Comparative Example 2. FIG.
3 is a flowchart of a method of treating anaerobic digestion sludge and anaerobic digestion wastewater (desalination solution) of food waste according to an embodiment of the present invention.
4 is a flowchart of a method of treating anaerobic digestion sludge and anaerobic digestion wastewater (desalination solution) of food waste according to another embodiment of the present invention.
5 is a schematic diagram of a treatment system of anaerobic digestion sludge and anaerobic digestion wastewater (desalination solution) of food waste according to an embodiment of the present invention.
6 shows agglomerated photographs of pre-digestion sludge reforming (agglomeration of unmodified sludge) and post-agglomeration of reforming sludge in Experimental Example 2. FIG.
FIG. 7 is a graph showing changes in COD of a desorbing liquid (inflow water) flowing into a membrane separation tank and a desorbing liquid (treated water) passing through a membrane separation tank according to the method of Example 1. FIG.
8 is a graph showing changes in nitrogen of a desorbing liquid (inflow water) flowing into a membrane separation tank and a desalination liquid (treated water) passing through a membrane separation tank according to the method of Example 1. FIG.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 3 is a flow chart of a method for treating anaerobic digestion wastewater of food waste according to an embodiment of the present invention, and FIG. 4 is a schematic diagram of a system for anaerobic digestion wastewater treatment of food waste according to an embodiment of the present invention.

Referring to FIG. 3, the present invention provides a method for treating garbage including an anaerobic digestion process,

(A) an anaerobic digestion sludge reforming step for improving anaerobic digestion ability of the anaerobic digestion sludge;

(B) a dewatering step of subjecting the modified anaerobic digestion sludge to solid-liquid separation into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And

(C) a method for disposing of food wastes,

The anaerobic digester sludge reforming step

(a1) removing anaerobic digestion residual gas by stirring; And

(a2) a sludge stabilization step through aeration,

The desalination treatment step

(c1) removing the suspended solids (SS) in the desolvation solution;

(c2) biological treatment after removing the suspended solids;

(c3) separating the membrane through the separation membrane after the biological treatment;

(c4) adjusting the pH of the membrane-separated desalin solution to ammoniumate the ammonia in the desalin solution; And

(c5) heating and concentrating the desalted solution having the pH adjusted therein, and a method for treating garbage.

5, the digester sludge reforming tank 20 removes anaerobic digestion residual gas from anaerobic digestion sludge discharged from the anaerobic digestion tank 10 and stabilizes sludge through aeration; A dehydrator 30 for separating the anaerobically digested sludge modified in the digestion sludge reforming tank 20 into solid phase dehydrated sludge cake and liquid anaerobic digestion wastewater desorption liquid; And a desorbing liquid treatment device (40) for treating the desorbing liquid, the system comprising: an anaerobic digestion wastewater treatment system for food waste,

The desalination apparatus 40 includes a suspended solids removal tank 41 for removing suspended solids (SS) in the desalination liquid; A biological treatment tank (42) for biological treatment of the desorbed liquid from which the suspended solids are removed; A membrane separation tank (43) for separating the biologically treated desalination liquid into a separation membrane; An ammonium tank 44 for adjusting the pH of the membrane-separated desalination solution to ammoniumate ammonia; And the pH-adjusted desalted solution And an evaporation concentrator (45) for separating the concentrated water into condensed water and condensed water by evaporation.

The purpose of the digestion sludge reforming tank 20 is to improve the dehydration ability of the anaerobic digestion sludge. By removing the residual gas from the anaerobic digestion process through agitation and reducing the pollution load due to simple aerobic digestion using aeration . Further, coagulation property of the sludge is increased by CO ₂ depletion and reduction of alkalinity, and the dewatering efficiency can be increased when the cohesiveness of the sludge is increased. The increase of dehydration efficiency showed the effect of reducing the amount of chemicals required for dehydration by about 30% or more, and it was confirmed that the concentration of dehydrated desalted solution can also be reduced. In addition, by controlling the bubbles during the pH adjustment in the post-ammonium tank and reducing the amount of sulfuric acid used, the TS in the influent water of the evaporator concentrator of FIG. 2 is reduced to about 35 to 40% It is possible to increase it. It is preferable that the aeration amount of the digestion sludge reforming tank is maintained so that the DO concentration in the reforming tank is maintained at 0.5 mg / L or less. In this range, it is confirmed that the improvement of the water quality of the desalination liquid and the reduction effect of the chemical amount are optimum.

In the method of treating food waste according to the present invention, after the anaerobic digestion sludge generated after the anaerobic digestion process is dehydrated, a dehydrated sludge cake and an anaerobic digestion wastewater (desalination solution) are produced.

The dewatered sludge cake can be discharged as it is or dried and discharged.

The anaerobic digestion wastewater (desalin solution) contains nitrogen and phosphorus at a high concentration, and can be treated according to the above-described anaerobic digestion wastewater (desalination solution) treatment process so as to efficiently remove nitrogen and phosphorus at a high concentration .

In step (S1) of the anaerobic digestion wastewater (desalin) treatment process, suspended solids in the wastewater (desalin solution) can be removed using one or more methods selected from coagulation sedimentation and flocculation. At this time, the anaerobic digestion wastewater (desalination solution) may be the anaerobic digestion wastewater (desalination solution) generated after the anaerobic digestion process.

The coagulation sedimentation is a method of adding a flocculant to the anaerobic digestion wastewater (desalting solution) to flocculate the suspended solids, and then precipitating the flocculated sediment. The flocculation flocculation is carried out by using a dissolved-air flotation method (DAF) And the like.

The suspended solids in the anaerobic digestion effluent (desolvation solution) are removed by the coagulation sedimentation or flocculation, and CO ₂ can also be deaerated, particularly when applying the pressurized flotation separation method. Since the suspended solids are removed from the anaerobic digestion wastewater (desalin solution), the efficiency of evaporation and concentration can be increased, scale formation can be prevented, and the suspended solids must be removed in order to facilitate the membrane separation process do.

The concentration of suspended solids in the wastewater (desalination solution) after removal of the suspended solids may be up to 1000 mg / L.

(S2) is a step of biologically treating the anaerobic digestion wastewater (desalination solution) after the removal of the suspended solids.

In the present invention, the biological treatment process is performed prior to the evaporation concentration process, so that the generation of the concentrated water in the evaporation concentration process, which is a post-process, can be remarkably reduced. Further, since the membrane separation, ammoniumation, and evaporation and concentration processes described below are performed sequentially after the biological treatment process, the biological treatment process has an advantage that no separate chemical treatment is required.

More specifically, in order to biologically treat the anaerobic digestion wastewater (desalination liquid), it is preferable to form a biological treatment tank composed of a biological reaction unit and a sedimentation unit, and to treat nitrogen and phosphorus using microorganisms in the biological reaction unit.

(S3), the anaerobic digestion wastewater (desalin solution) subjected to biological treatment can be subjected to a membrane separation process using a separation membrane.

The membrane separation step is a step for securing the quality of the wastewater (desolvation solution) to be connected and minimizing the concentrated water generated through the evaporation and concentration process as a post-process. This process has effectively played an effective role in facilitating the maintenance and management of the evaporation concentrator to be described later as the effluent of the effluent (desalination liquid) is more efficiently filtered than the existing gravity sediment.

 The separation membrane used in the membrane separation process is preferably a flat membrane or a hollow fiber membrane, but is not limited thereto.

(S4), the pH of the anaerobic digestion wastewater (desalination solution) that has undergone the membrane separation process can be adjusted to ammoniumate the ammonia in the desalination solution.

Sulfuric acid may be used as the pH adjusting agent, and ammonium produced from ammonia by the pH drop may remain in the concentrated water produced after evaporation concentration. That is, it is determined that the ammonia removal efficiency in the desalination liquid is higher as the content of ammonium remaining in the concentrated water produced after evaporation concentration is higher.

When the pH of the anaerobic digestion wastewater (desalin solution) is adjusted to 4.5-6 by using the pH adjusting agent, the content of ammonium remaining in the concentrated water produced after the concentration of the evaporation can be improved, Can be recycled to the digestion sludge reforming process and discharged in the form of a dehydrated sludge cake.

In this case, when the pH is controlled excessively, it may be difficult to control the pH accurately. Therefore, it may be possible to remove the bubbles by adding a defoaming agent. Also, it may be advantageous to adjust the pH more effectively by forming the ammonium tank in a multi stage rather than a single stage when adjusting the pH.

(S5), the wastewater (desalination solution) subjected to the ammoniumation process can be heated and concentrated by evaporation. At this time, the evaporation and concentration process can be performed using the evaporation concentrator used in the field of food processing.

When heat is applied to the wastewater (desalination solution) subjected to the membrane separation step, ammonium produced from ammonia is not evaporated together with water vapor but remains in the concentrated water for the most part.

According to this principle, it is possible to separate the ammonium-containing concentrated water and the condensed water generated after evaporation and concentration, and the weight of the ammonium-containing concentrated water and the condensed water may be 3-10% by weight of concentrated water and 90-97% by weight of condensed water, respectively . For example, the concentrate ratio after evaporation and concentration may be different by design, but it can be generally divided into 5 wt% of concentrated water and 95 wt% of condensed water. Here, the condensed water can be formed by condensing the water vapor generated in the evaporative condensation process.

It is possible to remove more than 90% of nitrogen, more than 99% of suspended solids, and more than 70% of organic matter (COD) compared to the pH-controlled anaerobic digestion wastewater (desalination solution) flowing into the evaporation concentration stage depending on the pH condition. Accordingly, the condensed water processed in the step S5 described later can satisfy the water quality of a level that allows the direct discharge.

(S5) is a step of separating and removing nitrogen and phosphorus through an evaporation concentration process. In the step (S5), the condensed water generated after the evaporation concentration can be discharged or treated in connection with a sewage treatment plant, The number can be processed separately.

4, when the concentrated water is recirculated, the concentrated water is recycled to the digested sludge reforming tank where the anaerobic digestion sludge stagnation process is performed, and then the concentrated water and the digested sludge are dehydrated in a mixed state to form a dehydrated cake Can be discharged.

In this case, the mixed weight of the concentrated water and the digested sludge may be 1-10 wt.% And 90-99 wt.%, Respectively, considering the removal efficiency of contaminants to be removed. When dehydrating after 22-26 hours, The pollutant can be discharged to the dehydrated sludge cake.

Thus, since the pollutants in the concentrated water are mostly discharged in the form of a dehydrated sludge cake, the concentration of water in the anaerobic digestion wastewater (desalted liquid) produced after the concentrated water and the anaerobic digested sludge are mixed and dehydrated is not mixed with concentrated water, The sludge is not significantly increased as compared with the anaerobic digestion effluent (desalted liquid) generated after dehydration.

The method of treating garbage of the present invention is characterized in that the concentrated water to be recycled is regulated according to measured values of TS (total solid), COD (chemical oxygen demand) or TN (total nitrogen) of the solid- do.

Measuring TS or COD or TN of the solid-liquid separated desalin; Measuring the amount of concentrated water recirculated to the anaerobic digester sludge reforming step; And increasing the TS, COD and TN of the solid-liquid separation effluent to decrease the amount of the recirculated concentrate and increasing the amount of the recirculated concentrated water when the TS, COD and TN of the solid-liquid separation effluent are decreased The concentrated water to be recycled can be adjusted by the step. At this time, the amount of the concentrated water can be adjusted as a valve provided on a pipe provided between the evaporation concentrator and the digestion sludge reforming tank.

The food garbage disposal system of the present invention may further include a control unit including a TS or COD or TN measuring apparatus of a solid-liquid separated desalination liquid and a concentrated liquid, wherein the control unit controls the TS and COD of the solid- Increasing the amount of the recirculated concentrated water and increasing the amount of the recirculated concentrated water when the TS, COD, and TN of the solid-liquid separated desalin decrease, and have.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope and content of the present invention can not be construed to be limited or limited by the following Examples. In addition, it is apparent that, based on the teachings of the present invention including the following examples, those skilled in the art can easily carry out the present invention in which experimental results are not specifically shown.

Example  One

Using the food garbage disposal apparatus of the present invention, the food garbage was treated at 400 liters / day according to the conditions shown in Table 1 below.

As the anaerobic digestion tank, anaerobic digestion of 400 liters / day of food waste was performed in a bio gas plant (BGP), and the anaerobic digested sludge was agitated and aerated and stabilized in a digestion sludge reforming tank.

The anaerobic digestion sludge was dehydrated using a dehydrator, and the resulting dehydrated sludge cake was dried and discharged.

The liquid desalted liquid produced after the digestion of the digested sludge was flocculated by adding a flocculant to remove suspended solids in anaerobic digestion wastewater (desalin).

Thereafter, the mixture was treated in a biological treatment tank according to a biological treatment method, passed through a membrane separator equipped with an MF flat membrane (PUREMBITECH), and then sulfuric acid was added thereto as a pH adjuster to adjust the pH to 5 to produce anaerobic digestion wastewater The ammonia in the desalted solution was ammoniumated.

The pH-adjusted anaerobic digestion wastewater (desalin solution) was heated to 110 ° C in an evaporator, concentrated by evaporation, and 3 wt% of the total weight of the wastewater (desalin solution) passed through the membrane separation tank was concentrated water and 97 wt% Respectively.

The concentrated water was treated separately, and the condensed water was discharged to perform food treatment.

Example  2

The anaerobic digestion wastewater of the food waste was treated in the same manner as in Example 1, and when the suspended solids were removed from the anaerobic digestion wastewater (desalination liquid), the suspended solids (SS) were removed by flocculation by a pressurized floating separation method using an aeration device Respectively.

Comparative Example  One

1, ammonia was stripped from the SS removal anaerobic digestion wastewater (desalting solution) by adding caustic soda to the pH of 11 to degas the ammonia in the form of gas, instead of ammonium concentration of the desalination solution of the example process And treated according to the biological treatment method.

Comparative Example  2

As a anaerobic digestion tank, anaerobic digestion of 400 liters / day of food waste was carried out in a bio gas plant (BGP), followed by anaerobic digestion sludge aeration and stabilization in the digestion sludge reforming tank.

The anaerobic digestion sludge was dehydrated using a dehydrator, and the resulting dehydrated sludge cake was dried and discharged.

The liquid desalted liquid produced after the digestion of the digested sludge was flocculated by adding a flocculant to remove suspended solids in anaerobic digestion wastewater (desalin).

Then, the pH of the anaerobic digestion wastewater (desalin solution) was adjusted to 5 to ammoniumate the ammonia in the anaerobic digestion wastewater (desalin solution).

The pH-adjusted anaerobic digestion wastewater (desalin solution) was heated to 110 ° C in an evaporator, concentrated by evaporation, and 3% by weight of concentrated water and 97% by weight of the total weight of the wastewater Respectively.

The concentrated water was treated separately and the condensed water was discharged after treatment according to the biological treatment method.

Comparative Example  3

Anaerobic digestion wastewater of food waste was treated in the same manner as in Example 1 except that the membrane separation tank was removed so that the wastewater (desalination liquid) passing through the biological treatment tank was directly introduced into the ammoniumation tank rather than the membrane separation tank.

Experimental Example  One: Digested sludge In the reforming tank  Water quality comparison

Each experiment was conducted to compare the water quality of the treated water with the aeration amount of the digested sludge reforming tank and the presence or absence of aeration. The operating conditions of the digested sludge reforming tank were pH 8.8 to 9.0, dissolved oxygen (DO) of 0.5 mg / Reduction potential (ORP) -10 to 20 mV.

The amount of aeration was checked at 0.5, 1, 3, 5, 10, 20 Lpm to confirm the changes in the water quality and the amount of sulfuric acid injected according to the aeration amount of the digestion sludge reforming tank. The results are shown in Table 1 below.

Aberration
(Lpm = L / min) Alkalinity
(mg / L as CaCO ₃₎ Polymer injection amount (0.2% dissolution) (L / ton) Desalination water quality Sulfate amount
(MVR inflow)
(Based on 95% sulfuric acid)
L / ton TS (mg / L) after sulfuric acid injection TS (mg / L) CODcr
(mg / L) TN
(mg / L) 0 13,240 150 9,130 3,830 3,632.7 5.5 23,210 20 9,240 150 13,435 8,790 2,711.7 3.0 - 10 9,710 150 10,065 4,877 2,408.3 3.3 - 5 10,220 150 10,020 4,581 2,584.9 3.7 19,550 3 11,050 150 9,750 4,326 2,691.7 3.8 19,380 One 11,920 150 9,720 4,202 2,739.3 4.6 20,355 0.5 12,510 150 9,480 4,089 2,801.4 5.2 22,870

As shown in Table 1, when the aeration amount is 3 Lpm, the optimum results are obtained when the desalination water quality and the sulfuric acid injection amount are compared. This is because the increase in the aeration rate is not an improvement of the desalinization water quality but the improvement of the quality of the desalinization solution only when the optimum aeration amount and the amount of the sulfuric acid injection amount are satisfied.

In addition, the desalination water quality according to presence or absence of aeration was compared in the digestion sludge reforming tank, and the results are shown in Table 2 below.

division Polymer injection rate (%) TS
(mg / L) SS
(mg / L) CODcr
(mg / L) TN
(mg / L) Before aeration 15 8,810 1,750 11,227 3,181 After aeration 12 6,800 430 1,781 3,014

As can be seen from the above Table 2, it can be seen that the water quality change of the desalination liquid after the aeration modification application is remarkably changed, and it is confirmed that the concentrated water can be remarkably reduced due to the aeration performance by the aeration in the digestion sludge reforming tank have.

Experimental Example  2: Digested sludge Reforming tank  Before and after drug use and Concentrated water  Emission comparison

The digestion sludge reforming tank was operated under the same conditions as Experimental Example 1, and the amounts of chemicals used and the amounts of concentrated water generated before and after the digestion sludge reforming were compared. The results are shown in Table 3 below. 6.

division Before digestion sludge reforming After digestion sludge reforming Reduced Polymer usage (ton / d) 34.5 28.8 5.7 Sulfuric acid consumption (ton / d) 3.7 2.5 1.2 Concentrated water generation (ton / d) 32.0 24.5 7.5

As shown in Table 3, the amount of polymer used was reduced by about 16%, the amount of sulfuric acid used was reduced by about 32%, and the amount of concentrated water was reduced by about 23% by performing digestion sludge modification according to the present invention. It is possible to reduce the amount of concentrate generated to 40% of the process of Comparative Example 2 by maximizing the concentration of solidification (TS) of process influent to a maximum of 30 times.

Experimental Example  3: Example  1 and Comparative Example  1 process efficiency comparison

The removal efficiencies of nitrogen and ammonia treated through the evaporation concentration process of Example 1 and the ammonia stripping process of Comparative Example 1 were compared and the results are shown in Table 4 below.

division Comparative Example 1 (ammonia stripping process) Example 1 (Evaporation Concentration Process) SS T-N NH ₃ -N SS T-N NH ₃ -N Primary Influent (mg / L) 593 1,535 1,195 161 2,239 1,937 Treated water (mg / L) 418 228 209 0 86 84 Throughput (% 30 85.1 82.5 100 96.2 96.1 Secondary Influent (mg / L) 312 1,411 1,098 313 2,170 1,822 Treated water (mg / L) 143 202 188 0 68 67 Throughput (% 54.2 85.7 82.9 100 96.8 96.3

As can be seen from Table 4, in the ammonia stripping process of Comparative Example 1, the throughput of the suspended solids (SS) was only 30% to 54.2% at maximum, whereas in the case of Example 1, the SS treatment rate reached 100% . In addition, it can be confirmed that the processing rate of total nitrogen (TN) and ammonia nitrogen (NH ₃ -N) is also remarkably excellent in the evaporation concentration process of Example 1.

Experimental Example  4: membrane Separation  Analysis of constituents of talli juice according to presence or absence

The nitrogen, phosphorus, suspended solids (SS) and COD changes of the desorbing liquid (inflow water) flowing into the membrane separation tank and the desorbing liquid (treated water) passing through the membrane separation tank were measured according to the method of Example 1, 7, 8, and Table 5 below.

division
(Unit mg / L) Influent Treated water nitrogen 3,540 1,121 sign 11 2 TS 10,760 8,943 COD 9,326 1,671

As a result, as shown in Table 5, it was confirmed that nitrogen, phosphorus, suspended solids (SS) and COD were significantly reduced when the desalination liquid was separated through the membrane separation tank.

Experimental Example  5: Example  1 and Comparative Example  2 Comparison of final discharge water quality

The CODcr, T-N, and SS values were measured to compare the final discharged water quality through the treatment methods of Example 1 and Comparative Example 2, and the results are shown in Table 6 below.

division Evaporation Concentration Influent TS (%) Evaporation Concentration Amount (ton / d) Concentrated water generation (ton / d) Final discharge water quality (mg / L) CODcr T-N SS Comparative Example 2 2.1 379 22 78 31 50 Example 1 1.3 385 13 26 13 0

As shown in Table 6, it can be seen that the final effluent quality of Example 1 is remarkably improved as compared with Comparative Example 2, and the quality of water is remarkably improved by the process of ammoniumation by means of the membrane separation tank after the biological treatment, This is the result that confirms that it can be improved.

That is, in other words, it is not possible to improve the water quality of the treated water simply by arbitrarily executing each process, but it is possible to prevent the contamination load of the dehydrating desalination liquid and to reduce the TS firstly by improving the deodorizing ability through the digestion sludge modification, The removal of suspended solids (SS) from the dehydrated desalin can be reduced by SSF and TS by applying a pressurized flotation separation method (DAF) using micro-bubbles. After the biological treatment, membrane separation is applied instead of existing gravity settling, It is possible to reduce the amount of TS to about 35-40% of the TS content of conventional evaporative condensation influent water, which can increase the efficiency up to 300% of the conventional condensation ratio. Therefore, Therefore, the above-described effects can be exhibited only when the process is carried out in the order according to the present invention.

It will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above and that various changes and modifications may be made without departing from the scope of the present invention as defined by the appended claims and without departing from the spirit or essential characteristics thereof. As shown in FIG.

It will be understood by those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention as defined by the appended claims and their equivalents. .

10: anaerobic digester
20: Digestion sludge reforming tank
30: Dehydrator
40: Desalination (anaerobic digestion wastewater) treatment device
41: suspended solids removal tank
42: Biological treatment tank
43: membrane separation tank
44: ammonium salt tank
45: Evaporation concentrator

Claims (22)

A method of treating food waste comprising an anaerobic digestion process,
(A) an anaerobic digestion sludge reforming step for improving anaerobic digestion ability of the anaerobic digestion sludge;
(B) a dewatering step of subjecting the modified anaerobic digestion sludge to solid-liquid separation into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And
(C) a waste liquid treatment step,
The anaerobic digester sludge reforming step
(a1) removing anaerobic digestion residual gas by stirring; And
(a2) a sludge stabilization step through aeration,
The desalination treatment step
(c1) removing the suspended solids (SS) in the desolvation solution;
(c2) biological treatment after removing the suspended solids;
(c3) separating the membrane through the separation membrane after the biological treatment;
(c4) adjusting the pH of the membrane-separated desalin solution to ammoniumate the ammonia in the desalin solution;
(c5) heating and concentrating the desalted solution having the pH adjusted therein; And
(c6) concentrating the concentrated water produced after the evaporation to the anaerobic digester sludge reforming step, and discharging the condensed water after the biological treatment,
The evaporation concentration in the step (c3) is carried out by separating the desorbing liquid into 3-10% by weight of ammonium-containing concentrated water and 90-97% by weight of condensed water,
In the step (c6), the recycled concentrated water and the anaerobic digested sludge are mixed at a ratio of 1-10% by weight and 90-99% by weight,
Wherein the concentrated water is recycled to the digested sludge reforming tank where the anaerobic digestion sludge is reformed and the concentrated water and the anaerobic digested sludge are mixed and aerated and then dehydrated and discharged to the dehydrated sludge cake,
Wherein the aeration is performed for 22-26 hours. The method according to claim 1, wherein the step (c1) comprises removing the suspended solids by at least one method selected from coagulation sedimentation by a drug and flocculation by pressurized powder phase separation. The method of claim 1, wherein the pH of the food waste is adjusted by using sulfuric acid as a pH adjuster. The food garbage disposal method according to claim 1, wherein the defoaming agent is further added to the step (c2). delete delete delete delete delete A digestion sludge reforming tank for improving the deodorizing ability of the anaerobic digestion sludge discharged from the anaerobic digestion tank;
A dehydrator for separating the anaerobically digested sludge modified in the digestion sludge reforming tank into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And
And a desorbing liquid treating apparatus for treating the desorbing liquid,
The desalination apparatus
A suspended solids removal tank for removing suspended solids (SS) in the desolvation solution;
A biological treatment tank for biological treatment of the desorbed liquid from which the suspended solids are removed;
A membrane separation tank for separating the biologically treated desolvation solution into a separation membrane;
An ammonium tank for ammoniumifying ammonia by adjusting the pH of the membrane-separated desalination liquid; And
The pH-adjusted desalted liquid And an evaporation concentrator for separating the concentrated water into condensed water and condensed water by evaporation,
In the evaporation concentrator, the influent water is concentrated by evaporation to separate 3-10 wt% of ammonium-containing concentrated water and 90-97 wt% of condensed water,
A pipe for recirculating the concentrated water concentrated by evaporation in the evaporation concentrator to the digester sludge reforming tank is installed between the evaporation concentrator and the digestion sludge reforming tank,
Wherein the digested sludge reforming tank is formed by mixing concentrated water recycled from the evaporation concentrator and anaerobic digested sludge at a ratio of 1-10% by weight and 90-99% by weight,
The concentrated water is recycled to the digested sludge reforming tank where the anaerobic digestion sludge is reformed, and after the concentrated water and the anaerobic digested sludge are mixed and aerated, they are dehydrated and discharged to the dehydrated sludge cake,
Wherein the aeration is performed for 22-26 hours. 11. The system of claim 10, wherein the suspended solids removal tank is one or more selected from the group consisting of coagulation sedimentation and coagulated sedimentation by pressure fractionation to remove suspended solids. 11. The system of claim 10, wherein sulfuric acid is added to the ammonium tank as a pH adjuster to adjust the pH of the desalination liquid. 11. The system according to claim 10, wherein bubbles are removed by adding an antifoaming agent in the ammoniumification tank. delete delete delete delete delete A method of treating food waste comprising an anaerobic digestion process,
(A) an anaerobic digestion sludge reforming step for stabilizing anaerobic digestion sludge by aeration;
(B) a dewatering step of subjecting the modified anaerobic digestion sludge to solid-liquid separation into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And
(C) a stripping liquid treatment step,
The desalination treatment step
(c1) removing the suspended solids (SS) in the desolvation solution;
(c2) biological treatment after removing the suspended solids;
(c3) separating the membrane through the separation membrane after the biological treatment;
(c4) adjusting the pH of the membrane-separated desalin solution to ammoniumate the ammonia in the desalin solution;
(c5) heating and concentrating the desalted solution having the pH adjusted therein; And
(c6) concentrating the concentrated water produced after the evaporation to the anaerobic digester sludge reforming step, and discharging the condensed water after the biological treatment,
The amount of the concentrated water to be recycled is adjusted according to the measurement values of TS (total solid) or COD (total oxygen demand) or TN (total nitrogen) of the solid-
The evaporation concentration in the step (c3) is performed by separating the desorbing liquid into 3-10% by weight of ammonium-containing concentrated water and 90-97% by weight of condensed water,
In the step (c6), the recycled concentrated water and the anaerobic digested sludge are mixed at a ratio of 1-10% by weight and 90-99% by weight,
The concentrated water is recycled to the digested sludge reforming tank where the anaerobic digestion sludge is reformed, and after the concentrated water and the anaerobic digested sludge are mixed and aerated, they are dehydrated and discharged to the dehydrated sludge cake,
Wherein the aeration is performed for 22-26 hours. 20. The method of claim 19, further comprising: measuring TS or COD or TN of the solid-liquid separated desalin;
Measuring the amount of concentrated water recirculated to the anaerobic digester sludge reforming step; And
Decreasing the amount of recycled concentrated water when the TS, COD and TN of the solid-liquid separated desalin solution is increased, and increasing the amount of the recycled concentrated water when the TS, COD and TN of the solid- And adjusting the amount of the recycled concentrated water by the amount of the concentrated water. A digestion sludge reforming tank for aerating and stabilizing the anaerobic digestion sludge discharged from the anaerobic digestion tank;
A dehydrator for separating the anaerobically digested sludge modified in the digestion sludge reforming tank into a solid phase dehydrated sludge cake and a liquid phase anaerobic digestion effluent; And
And a desorbing liquid treating apparatus for treating the desorbing liquid,
The desalination apparatus
A suspended solids removal tank for removing suspended solids (SS) in the desolvation solution;
A biological treatment tank for biological treatment of the desorbed liquid from which the suspended solids are removed;
A membrane separation tank for separating the biologically treated desolvation solution into a separation membrane;
An ammonium tank for ammoniumifying ammonia by adjusting the pH of the membrane-separated desalination liquid;
The pH-adjusted desalted liquid An evaporation concentrator for evaporating and concentrating the water into concentrated water and condensed water; And
And a control unit including the TS or the COD or TN measuring device of the solid-liquid separated desalination liquid and concentrated water,
In the evaporation concentrator, the influent water is concentrated by evaporation to separate 3-10 wt% of ammonium-containing concentrated water and 90-97 wt% of condensed water,
A pipe for recirculating the concentrated water concentrated by evaporation in the evaporation concentrator to the digester sludge reforming tank is installed between the evaporation concentrator and the digestion sludge reforming tank,
Wherein the digested sludge reforming tank is formed by mixing concentrated water recycled from the evaporation concentrator and anaerobic digested sludge at a ratio of 1-10% by weight and 90-99% by weight,
The concentrated water is recycled to the digested sludge reforming tank where the anaerobic digestion sludge is reformed, and after the concentrated water and the anaerobic digested sludge are mixed and aerated, they are dehydrated and discharged to the dehydrated sludge cake,
Wherein the aeration is performed for 22-26 hours. 22. The method of claim 21, wherein the controller reduces the amount of concentrated water recirculated when the TS and COD and TN of the solid-liquid separated effluent increase, and reduces the amount of the recirculated concentrated water when the TS, COD, and TN of the solid- Increasing the amount of the concentrated water to regulate the amount of the recycled concentrated water.

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