JPH10296299A - Method for removing polychlorinated-dibenzo-p-dioxins in sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove polychlorinated-dibenzo-p-dioxins in sludge. SOLUTION: When wastewater containing polychlorinated-dibenzo-p-dioxins is treated by a calcium-removing facility, a bioremediation facility, a coagulation-treatment facility, and a hazardous matter-treating facility and sludge 3a, 4a, 5a produced by each of the facilities are treated, the polychlorinated-dibenzo-p-dioxins is decomposition-removed by a method wherein eluent of the polychlorinated-dibenzo-p-dioxins 58 is added into the sludge 3a, 4a, 5a and the polychlorinated-dibenzo-p-dioxins in sludge 55, 56 is allowed to be eluted into the eluent of the polychlorinated-dibenzo-p-dioxins 58 and desorbed water 62 containing the eluent of the polychlorinated-dibenzo-p-dioxins 58 is returned to the hazardous matter-treating facility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing dioxins in sludge for removing dioxins from sludge generated when treating leachate at a final disposal site for waste.

[0002]

2. Description of the Related Art Conventionally, sewage containing harmful substances such as dioxins, such as leachate at a final landfill of general and industrial wastes, is treated as follows. .

[0003] Sewage is introduced into a pretreatment facility to remove contaminants and sand, etc., and then water quality and water amount are adjusted. This pretreatment water is introduced into a calcium removal facility, and calcium and manganese in the pretreatment water are removed. Heavy metals such as the above are aggregated, the aggregates are separated by settling, and the supernatant water is neutralized.

[0004] The calcium-removed water is introduced into a biological treatment facility, and sequentially flows into an anaerobic tank and an aerobic tank to decompose and remove BOD substances and TN in the calcium-removed water by the action of microorganisms. The obtained biologically treated water is introduced into a coagulation sedimentation treatment facility, where COD substances, suspended substances, TP, etc. in the biologically treated water are aggregated, and the aggregates are settled and separated.

[0005] The coagulated sedimentation water is introduced into a sand filtration tower to remove fine suspended substances in the coagulated sedimentation water, and then introduced into an ozone / ultraviolet reactor and an activated carbon adsorption tower to remove remaining dioxins. , COD substances, chromaticity components, etc. are removed to obtain treated water.

[0006] At this time, the sludge generated in the calcium removing facility, the biological treatment facility, and the coagulation sedimentation facility is treated as follows. Sludge generated in each facility is transferred to a sludge thickening tank and concentrated, and the concentrated sludge is transferred to a sludge storage tank and temporarily stored therein. The concentrated sludge is taken out of the sludge storage tank by a sludge pump, added with a dehydration aid and dewatered by a sludge dewatering machine, and the dewatered cake is stored in a cake hopper and then carried out for disposal. The concentrated separated liquid and the dewatered filtrate separated in the sludge thickening tank, sludge storage tank, and sludge dewatering machine are returned to the pretreatment equipment,
The above series of sewage treatment is performed.

[0007]

However, dioxins are also contained in the sludge generated in each of the above facilities, and therefore, the desorbed liquid from which dioxins have been eluted is discharged from the sludge dewatering machine. . Therefore, in the conventional method of returning the concentrated separated liquid or the dehydrated filtrate to the pretreatment equipment as it is, the dioxins pass through the pretreatment equipment without dioxin decomposability, the calcium removal equipment, and the coagulation sedimentation treatment equipment, and the water treatment is carried out. It is concentrated in the equipment system.

The present invention has been made to solve the above problems, and has as its object to efficiently decompose and remove dioxins in sludge to render them harmless.

[0009]

In order to solve the above-mentioned problems, a method for removing dioxins in sludge according to the present invention comprises the steps of treating wastewater containing dioxins with a biological treatment facility, a coagulation treatment facility, an ozone / ultraviolet treatment facility. In treating the sludge generated in the biological treatment equipment and the coagulation treatment equipment, the dioxin eluent is added to the sludge to elute dioxins in the sludge into the dioxin eluent,
The sludge containing the dioxin eluate is dewatered by a dewatering means, the separated water from the sludge discharged from the dewatering means and the dioxin eluate are returned to the ozone / ultraviolet treatment equipment, and the dioxins in the dioxin eluate are removed. It is decomposed and removed by ozone and ultraviolet rays.

As the dioxin eluent, acetone,
Acetonitrile, benzene, DMSO, chlorobenzene, o-dichlorobenzene, LAS (sodium linear alkylbenzene sulfonate) and the like can be used.

[0011] With the above structure, dioxins in sludge can be efficiently decomposed and removed by effectively utilizing equipment for treating wastewater.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show a schematic overall configuration of a sewage treatment facility for treating sewage containing harmful substances such as dioxins, such as leachate from a general waste landfill or an industrial waste landfill. The processing facility
Pretreatment facility 2 and calcium removal facility 3 into which sewage 1 flows
And biological treatment equipment 4, coagulation and sedimentation treatment equipment 5, trace harmful substance removing equipment 6, activated carbon adsorption tower 7, and sludge treatment equipment 8.

The sewage treatment flow in this sewage treatment facility is as follows. First, sewage water 1
And the contaminants and sand are removed in the settling tank 8 and the adjusting tank 9
Adjust the water quality and quantity with.

The pretreated water 10 is supplied to the calcium removal equipment 3
And the calcium in the pretreatment water 10 is converted into calcium carbonate by the sodium carbonate 12 in the reaction tank 11, and then sequentially introduced into the mixing tank 13 and the coagulation tank 14, and heavy metals such as manganese in the pretreatment water 10 are introduced. Is coagulated with a coagulant 15 and a coagulation aid 16, and aggregates of calcium carbonate and heavy metals are settled and separated in a sedimentation tank 17, and supernatant water in the sedimentation tank 17 is introduced into a neutralization tank 18 for neutralization. . 19, 20, 21 are pH adjusters.

The calcium removal water 22 flowing out of the calcium removal equipment 3 is introduced into the biological treatment equipment 4 and
3 and the nitric acid solution 25 in the aerobic tank 24 is circulated to the anaerobic tank 23, and phosphoric acid 26 and methanol 27 are added as necessary, so that BOD substances and TN are decomposed and removed by microorganisms.

Biological treated water 2 flowing out of biological treatment facility 4
8 is introduced into the coagulation sedimentation treatment equipment 5, and the coagulant 31 and the coagulation aid 32 are sequentially added in the mixing tank 29 and the coagulation tank 30, whereby COD substances, suspended substances, T
-P and the like are aggregated, the aggregates are settled and separated in the sedimentation tank 33, and the supernatant water in the sedimentation tank 33 is guided to the neutralization tank 34 for neutralization, and then to the raw filtration water tank 35. 36 and 37 are pH adjusters.

The coagulated sedimentation treatment water 39 flowing out of the coagulation sedimentation treatment equipment 5 is introduced into the harmful substance removing device 6 through the sand filtration tower 40 and the filtration treatment water tank 41, and while passing through the inside of the reaction tank 42, an ultraviolet lamp is used. Irradiation with ultraviolet rays from 43 and contact with high concentration ozone supplied from an ozone generator 44 to dissolve soluble organic pollutants such as dioxins and other remaining COD substances contained in the coagulated sedimentation water 39. Decompose. The discharged ozone 45 is led to an ozone treatment tower (not shown).

The ultraviolet light flowing out of the harmful substance removing device 6
The ozonated water 46 is introduced into the activated carbon adsorption tower 7 through the activated carbon raw water tank 47, passes through a layer of activated carbon 48 filled in the tower, and dioxins and heavy metals remaining in the ultraviolet / ozonated water 46 are removed by activated carbon. Remove by adsorption.

The activated carbon treated water 49 flowing out of the activated carbon adsorption tower 7 is introduced into an activated carbon treated water tank 50, a part of which is circulated back to the activated carbon adsorption tower 7 as a circulating liquid 51, and the rest is treated water 52 as final neutralized water. Discharge through a tank and a disinfection tank (not shown).

At this time, the sludge generated in the calcium removal equipment 3, the biological treatment equipment 4, and the coagulation sedimentation equipment 5, respectively, is treated as follows. Calcium removal equipment 3
The sludge 3a generated in the above is introduced into the first sludge concentration tank 53 and concentrated, and the sludge 4a generated in the biological treatment equipment 4 and the sludge 5a generated in the coagulation sedimentation treatment equipment 5 are introduced into the second sludge concentration tank 54. And concentrate. The concentrated sludge 5 in the first sludge thickening tank 53
5 and the concentrated sludge 56 in the second sludge concentration tank 54 are transferred to a sludge storage tank 57 and temporarily stored therein.

At an appropriate time, the concentrated sludge 55, 56 in the sludge storage tank 57 is added to a dioxin eluent 5 such as DMSO.
8 and stirred to elute dioxins in the concentrated sludge 55 and 56 into the dioxin eluent 58.

The concentrated sludge 59 containing the dioxin eluent 58 is taken out of the sludge storage tank 57, and after adding a dehydration aid 60, it is dewatered by a sludge dehydrator 61 such as a filter press. The desorbed water 62 composed of the separated water from the concentrated sludge 59 discharged from the sludge dewatering device 61 and the dioxin eluent 58 is passed through the filtration raw water tank 35, the sand filtration tower 40, and the filtration water tank 41 to remove harmful substances. The dioxins in the desorbed water 62 are decomposed and removed by ozone and ultraviolet rays together with the dioxins and other COD substances contained in the flocculated water 39 and flown.

The separated water 63, 64 separated in the first and second sludge concentration tanks 53, 54 and the separated water 65 separated in the sludge storage tank 57 before the dioxin elution operation are returned to the pretreatment facility 2. Then, the above series of sewage treatment is performed. The dewatered cake 66 discharged from the sludge dewatering machine 61 is carried out to a landfill or the like.

According to the above-described treatment method, dioxins in sludge can be efficiently removed by effectively utilizing the harmful substance removing device 6 conventionally used only for sewage treatment.

As the dioxin eluent 58, in addition to the above-described DMSO, LAS (sodium linear alkylbenzene sulfonate), benzene, acetone, chlorobenzene, acetonitrile, o-dichlorobenzene and the like can be used. For example, for 2% sludge, DMSO
In the case of, a 10 to 20% concentration sludge is added in an amount equal to or greater than the amount of sludge, and benzene (or acetone, chlorobenzene,
20 in the case of acetonitrile, o-dichlorobenzene)
% Sludge is added in an amount equal to or greater than the amount of sludge.

[0026]

As described above, according to the present invention, the dioxins in the sludge are eluted by the dioxin eluent, so that the ozone / ultraviolet reactor for sewage treatment can be effectively used, and the sludge can be effectively used. Dioxins contained therein can be efficiently decomposed and removed to make them harmless.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the configuration of each facility from which sludge to be treated is discharged is a sewage treatment facility in which a sludge treatment method of the present invention is implemented.

FIG. 2 is an explanatory diagram showing the configuration of the sludge treatment facility, which is the wastewater treatment facility shown in FIG.

[Explanation of symbols]

 1 Wastewater 3 Calcium removal equipment 4 Biological treatment equipment 5 Coagulation treatment equipment 3a, 4a, 5a Sludge 6 Hazardous substance removal equipment (ozone / ultraviolet reactor) 55,56 Condensed sludge 57 Sludge storage tank 58 Dioxin eluent 62 Dewatering water

Claims (1)

[Claims] 1. A wastewater containing dioxins is treated by a biological treatment facility, a coagulation treatment facility, and an ozone / ultraviolet treatment facility, and the sludge generated in the biological treatment facility and the coagulation treatment facility is treated with the sludge. The dioxin eluent is added to elute the dioxins in the sludge into the dioxin eluent, the sludge containing the dioxin eluate is dehydrated by the dewatering means, and the separated water and dioxin eluted from the sludge discharged from the dewatering means The liquid and the ozone
A method for removing dioxins in sludge, comprising returning the dioxins in a dioxin eluent to ozone and ultraviolet rays by returning the dioxins to an ultraviolet treatment facility.