KR101074035B1 - On-site sludge composting method for small-scale sewage treatment plant - Google Patents

Abstract

Disclosed is a sludge treatment apparatus and method for a small sewage treatment plant.

In the sludge treatment apparatus of a small sewage treatment plant according to an embodiment of the present invention, the sludge is separated into a solid phase and a liquid phase, and the solid-liquid separator 110 for making a sludge mixture by mixing the solid phase and the swelling material is heated to a constant temperature. Aerobic fermentation apparatus 120 for fermentation, post-aging apparatus 130 for post-aging and stabilizing fermented sludge mixture, sorting apparatus 140 for separating composted sludge mixture into compost and swelling material, aerobic fermentation apparatus 120 And an air pump 150 for supplying external air to the post-housing device 130 and a control device 160 for controlling the operation of the entire device, and having a high water content without a separate pretreatment process such as drying or dehydration. Sludge can be composted on-site, preventing re-emission of phosphorus in the reservoir and promoting sludge treatment.

Small scale sewage treatment plant, sewage sludge, biological removal, re-release of phosphate, composting

Description

Sludge treatment method in small sewage treatment plant {ON-SITE SLUDGE COMPOSTING METHOD FOR SMALL-SCALE SEWAGE TREATMENT PLANT}

The present invention relates to a treatment apparatus for composting sewage sludge generated in a small sewage treatment plant, and more particularly, to substantially reduce water discharge by periodically drawing sewage sludge having a high water content and composting in the field to substantially contribute to water quality improvement. The present invention relates to a sludge treatment apparatus and method for a small sewage treatment plant capable of immediately reducing the continuously generated compost to a green farmland of a nearby area.

Recently, sewage sludge has been banned and marine dumping has become difficult to deal with. As effluent water quality standards are strengthened, the process of removing nutrients such as nitrogen and phosphorus is essential in small sewage treatment facilities.

In the case of phosphorus removal, a biological removal process that induces luxury uptake of phosphorus by using Phosphate Accumulation Organisms (PAO), which is a phosphorus removal microorganism, is adopted, and the phosphorus thus removed from the water treatment system is contained in the sludge. It exists in an integrated state.

The small sewage treatment plant in the rural area is operated by an unmanned system without manpower, so the sludge generated is transported to the nearby medium-sized sewage treatment plant at a frequency of 1 ~ 2 times a year. It is left in the reservoir for a long time.

As such, when the sludge containing phosphorus stays in the storage tank for a long time, phosphorus is re-emitted from the sludge into sewage under anaerobic conditions.Re-discharged phosphorus is included in the sewage and returned to a bioreactor or a flow control tank, thereby substantially removing Difficult to expect effect.

Therefore, there is a need for a method that can utilize the sludge generated at the same time to solve the problem of re-released phosphorous from the sludge by utilizing the sludge generated in the small sewage treatment plant in the field without moving to the medium and large sewage treatment plant.

It is preferable to compost the sludge on site as this method, but in the case of the sewage sludge which is not dehydrated, the water content is very high, around 99%, which is a problem.

In other words, when composting sludge, the water content is 50 to 60%, so it is necessary to lower the water content through dehydration. However, it is difficult to equip a separate sewage treatment plant in a small sewage treatment plant that is operated unattended. There is a problem that it is practically impossible to do.

Accordingly, an object of the present invention for solving the above problems is to provide a sludge treatment apparatus of a small sewage treatment plant to facilitate the composting operation in a small sewage treatment plant to promote the treatment of sludge.

Another object of the present invention is to provide a sludge treatment apparatus of a small sewage treatment plant which can prevent the re-release of phosphorus from the sludge in the storage tank of the small sewage treatment plant.

In addition, another object of the present invention is to provide a sludge treatment apparatus of a small sewage treatment plant that can be composted on-site by using the sludge of the high water content as it is without a separate pretreatment process such as drying or dehydration.

Another object of the present invention is to provide a sludge treatment apparatus of a small sewage treatment plant capable of composting sludge of a small sewage treatment plant on site.

According to an aspect of the present invention,

A solid-liquid separation device for separating the sludge introduced from the storage tank into a solid phase and a liquid phase, and returning the liquid phase to the storage tank, and mixing the solid phase with the swelling material to adjust the initial water content of the sludge to 60 to 70%;

An aerobic fermentation apparatus for fermenting the sludge mixture introduced from the solid-liquid separator while being heated at a constant temperature by a heat source in an aerobic state;

A post-boiling apparatus for completing the compost by incubating and stabilizing the sludge mixture introduced from the aerobic fermentation apparatus in an aerobic state;

A sorting device for separating the swelling material from the sludge mixture introduced from the post-boiling apparatus, transferring the composted sludge to the adjacent green farmland, and transferring the sorted swelling material to the solid-liquid separator to be recycled;

An air pump for supplying air so that the aerobic fermentation apparatus and the post-warmer are maintained aerobic; And

A control device for operating the respective devices and controlling the entire processing device; It provides a sludge treatment apparatus of a small sewage treatment plant comprising a.

The solid-liquid separator includes a floating valve for sucking and discharging the liquid phase of the upper layer portion at the interface between the solid and liquid phases, an agitator for mixing the solid sludge and the swelling material, and an opening and closing device for discharging the stirred sludge mixture downward.

The liquid phase flowing out of the solid-liquid separator is returned to the bioreactor or flow rate adjustment tank.

Sludge introduced into the solid-liquid separator is preferably suspended for 24 to 36 hours to separate the liquid phase and the solid phase.

The swelling material may be made of any one or more of wood chips, sawdust or chaff.

In the aerobic fermentation apparatus, it is preferable to hold the sludge mixture introduced therein for 8 to 12 days while maintaining the internal temperature at 50 to 55 ° C.

The sludge treatment apparatus may further include a biofilter for collecting and treating odor generated.

It is preferable to install a screw conveyor between the solid-liquid separator, aerobic fermentation apparatus, a post-aging apparatus and a sorting apparatus to simultaneously carry out the transport and stirring of the sludge mixture.

In addition, the present invention, in order to achieve the above object,

A first step of introducing the sludge of the storage tank into the solid-liquid separator and separating the solid phase and the liquid phase, then returning the liquid phase to the storage tank and mixing the solid phase with the swelling material to adjust the initial water content of the sludge to 60 to 70%;

A second step of introducing the sludge mixture of the solid-liquid separator into the aerobic fermentation apparatus while fermenting while heating to a predetermined temperature in an aerobic state;

A third step of introducing the sludge mixture of the aerobic fermentation apparatus into a post-preparation apparatus to incubate and stabilize in aerobic state to complete the compost;

After the sludge mixture of the post-boiling device is introduced into the sorting device to separate the swelling material from the sludge mixture, the composted sludge is transferred to the adjacent green farmland, and the sorted swelling material is transferred to the solid-liquid separator and recycled. ; And

A fifth step of checking whether or not there is sludge in the storage tank, if the sludge is present, proceeding to the first step again; It provides a sludge treatment method of a small sewage treatment plant.

Preferably, the aerobic fermentation apparatus and the post-aging apparatus continuously supply external air by an air pump to maintain aerobic characteristics.

In the first step, in the solid-liquid separator, a floating valve is installed at the sludge interface to suck the liquid phase of the upper layer portion and return it to the bioreactor or the flow adjusting tank, and the lower portion is discharged to discharge the sludge mixture mixed with the solid sludge and the swelling material. An opening and closing device is installed at the inside, and an agitator can be installed inside to mix the solid sludge and the swelling material.

In the first step, the sludge introduced into the solid-liquid separator is preferably held for 24 to 36 hours to separate the liquid phase and the solid phase, the swelling material may be made of any one or more of wood chips, sawdust or rice husk. .

In the second step, the aerobic fermentation apparatus is preferably to hold the sludge mixture for 8 to 12 days while maintaining the internal temperature at 50 to 55 ℃.

The sludge treatment method may collect and treat odor generated during the treatment process as a biofilter at the same time as the first to fourth steps.

It is preferable to install a screw conveyor between the solid-liquid separator, the aerobic fermentation apparatus, the post-aging apparatus and the sorting apparatus, respectively, to stir the sludge mixture simultaneously with the transfer.

According to the sludge treatment apparatus and method of the small sewage treatment plant of the present invention, phosphorus is re-released from the sludge in the storage tank by allowing the sludge of the high water content to be composted on site without any pretreatment such as drying or dehydration. It is possible to prevent sludge and facilitate the composting operation to promote the treatment of sludge.

The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may properly define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meanings and concepts corresponding to the technical spirit of the present invention.

Hereinafter, a sludge treatment apparatus of a small sewage treatment plant according to an embodiment of the present invention will be described based on the accompanying drawings.

1 is a block diagram showing the overall configuration of a sludge treatment apparatus according to an embodiment of the present invention, referring to the drawings, the sludge treatment apparatus of a small sewage treatment plant according to an embodiment of the present invention is a sludge solid and liquid Solid-liquid separator (110) for separating and mixing the solid phase and the swelling material to make a sludge mixture, aerobic fermentation apparatus (120) for heating the sludge mixture to a certain temperature for fermentation, and post-aging apparatus for post-aging and stabilizing the fermented sludge mixture. 130, the sorting device 140 for separating the composted sludge mixture into the compost and swelling material, the air pump 150 for supplying external air to the aerobic fermentation device 120 and the post-treatment device 130 and the entire device It includes a control device 160 for controlling the operation of these.

With reference to the drawings will be described in detail with respect to each of the components as follows.

2 is a cross-sectional view schematically showing the solid-liquid separation device in one embodiment of the present invention. As can be seen in the figure, the sludge inlet 103 for introducing the sludge of the storage tank 100 and the swelling material inlet 143 for introducing the swelling material into the tank is installed on the upper portion of the solid-liquid separator 110. Floating valve 112 is installed inside and floats along the interface between the solid sludge 10 and the liquid sewage 20 and flows the upper liquid sewage 20 into the storage tank 100 through the outlet pipe 102. Return it.

That is, the sludge in the solid-liquid separator 110 is separated into the solid sludge 10 and the liquid sewage 20, and the liquid sewage 20 flows out toward the storage tank 100 to be a bioreactor (not shown) or a flow adjusting tank (not shown). Is returned. In addition, the floating valve 112 is installed at the interface between the solid phase and the liquid phase in consideration of the fact that the interface between the concentrated solid phase may vary according to the amount of sludge and the suspended state.

3 is a graph showing the water content of the sludge drawn in the storage tank 100 and the volume change of the concentrated sludge according to the time, the water content of the sludge decreases depending on the concentration time, but is not concentrated any more after about 30 hours You can see that it doesn't.

Therefore, in order to separate the sludge introduced from the storage tank 100 into the liquid phase and the solid phase, it is preferable to hold the sludge in the solid-liquid separator 110 for 24 to 36 hours, at which time the water content is 96 to 98%. Is in the range of.

In addition, the inside of the solid-liquid separator 110 is provided with a stirrer 114 for mixing the swelling material and the solid sludge 10 in order to lower the water content of the solid sludge 10, the lower portion of the sludge mixture is stirred An opening and closing device 113 for discharging is provided.

Solid sludge 10, the initial moisture content of about 96 to 98% concentration is mixed with the swelling material to be lowered to about 60 to 70% in the solid-liquid separator 110, and then aerobic fermentation through the opening and closing device 113 Ejected towards device 120. The swelling material may be wood chips, sawdust, rice hulls or mixtures thereof.

The optimum water content of aerobic composting is known to be 50 to 60%, but the water content of concentrated sludge is in the range of 96 to 98%. When controlling the water content with swelling material, not only excessive swelling material is required but also degradable organic substances As the content of is lowered, the progress of the effective composting reaction becomes difficult.

Therefore, in one embodiment of the present invention, the water content is controlled by the swelling material to a level of 60 to 70% higher than the initial water content in the conventional composting process, and the initial composting reaction in the aerobic fermentation apparatus 120 is a heat source 122 ) To maintain the fermentation temperature.

Next, the aerobic fermentation device 120 is a device for fermenting the sludge mixture introduced from the solid-liquid separator 110 while heating to a constant temperature in an aerobic state, a heat source for supplying heat to the outside of the aerobic fermentation device 120 122 is provided. The heat source 122 is provided with a temperature control device that can maintain the aerobic fermentation apparatus 120 at a constant temperature, such as a heating film or hot air blower.

The aerobic fermentation apparatus 120 preferably maintains an internal temperature in the range of 50 to 55 ° C. by heating the heat source 122, and preferably, the sludge mixture is allowed to stand for 8 to 12 days.

Figure 4 shows the change in moisture content during the composting process according to the initial moisture content in one embodiment of the present invention, by installing a heating film as a heat source 122 in the aerobic fermentation apparatus as described above 50 to the internal temperature As a result of observing the progress of the composting reaction while controlling to maintain at 55 ℃, it can be seen that after about 9 days the water content is lowered to 60% or less as shown in the figure.

In addition, since the aerobic fermentation apparatus 120 should always be maintained in the aerobic state, the outside air is continuously supplied from the air pump 15 installed outside. When the supply amount is excessively cooled, the temperature is lower than the appropriate temperature, and when the supply amount is small, it is difficult to maintain the aerobic state, so the proper supply amount is about 50 to 200 L / min per 1 m 3, which is controlled by the controller 160.

In addition, since the sludge mixture in the aerobic fermentation apparatus 120 may have a liquid phase at a lower portion due to the solid-liquid separation phenomenon generated by its own weight, the bottom of the aerobic fermentation apparatus 120 may be inclined by about 2 to 5 degrees, and the coke may be lowered. It is desirable to install the si) to discharge the collected liquid.

Next, the post-aging device 130 is a device for completing the compost by incubating and stabilizing the sludge mixture introduced from the aerobic fermentation device 120 in an aerobic state.

When the microorganism reaches the range of water in which it can function properly, it is necessary to stop the warming and go through the housing time to supply only the proper amount of air. This period is about 5 to 6 days, after which the sludge compost is completed.

Since the inside of the after-aging device 130 must maintain an aerobic state similarly to the aerobic fermentation device 120, the outside air is continuously supplied from the air pump 15 installed outside. This is also the proper supply of air is made and controlled by the controller 160.

Next, the sorting device 140 separates the swelling material from the sludge mixture introduced from the after-treatment device 130, and the composted sludge is separated into the solid-liquid separator 110 so that the swelling material selected by the adjacent green farmland is recycled. It is a device to transfer. That is, in the after-aging device 130, the composted sludge mixture is separated into swelling material and the final product compost, and the compost is transferred to the green farmland 200, and the swelling material is returned to the high temperature fermentation tank for reuse.

Preferably, the swelling material has a particle size of about 5 to 15 mm to facilitate separation from the composted sludge as a final product. Figure 5 is a graph showing the change in the water content according to the size of the swelling material in the embodiment of the present invention, the smaller the size of the swelling material, as shown in the drawing is advantageous to the composting reaction, but the sorting operation and swelling of the produced compost Considering the recycling aspect of the ash, the optimum size is preferably about 5 to 15mm.

In addition, the air pump 150 in FIG. 1 is a device for supplying air to maintain the aerobic fermentation apparatus 120 and the post-treatment device 130 as described above, the control device 160 is the respective devices It drives the fields 110, 120, 130, 140, 150 and controls the operation.

In order to operate the entire system unattended, the solid-liquid separation device 110, aerobic fermentation device 120, the post-warming device 130 and the sorting device 140 are sequentially arranged inside the oval ring configured to circulate infinitely, Screw conveyors (111, 121, 131, 142) between each device is preferably configured to be moved at regular time intervals while simultaneously performing the transport and agitation of the sludge mixture. The moving speeds of the screw conveyors 111, 121, 131, and 142 are adjusted by the controller 70 so as to satisfy the residence time required by each device.

On the other hand, the sludge treatment apparatus according to an embodiment of the present invention preferably further includes a biofilter 170 for collecting and treating the odor generated during the entire process of treating the sludge.

Next, a sludge treatment method of a small sewage treatment plant according to an embodiment of the present invention will be described. 6 is a flowchart illustrating a sludge treatment method according to an embodiment of the present invention at each stage, which will be described with reference to FIGS. 1 to 6.

First, in the first step (S1), the sludge of the storage tank 100 is introduced into the solid-liquid separator 110 and separated into a solid phase and a liquid phase, the liquid sewage 20 is returned to the storage tank 100 and the solid sludge 10 ) Is mixed with the swelling material to adjust the initial moisture content of the sludge to 60 to 70%.

That is, the solid phase and the liquid phase are separated by stabilizing the sludge in the solid-liquid separator 110 for about 24 to 36 hours, and the liquid phase is extracted and conveyed from the interface to obtain concentrated sludge, and the water content of the sludge is 96 To 98%. The swelling material such as wood chips or sawdust is mixed with the solid sludge 10 to be adjusted to a level of 60 to 70% higher than the initial moisture content in a conventional composting process.

Next, in the second step S2, the sludge mixture of the solid-liquid separator 110 is introduced into the aerobic fermentation apparatus 120 and fermented while heating to a predetermined temperature in an aerobic state.

That is, while controlling the aerobic fermentation apparatus 120 to maintain the internal temperature 50 to 55 ℃ while heating the heat source 122, such as a heating film so that the moisture content is lowered to 60% or less. In this case, the required period is preferably in the range of 8 to 12 days, and the supply amount of external air by the air pump 150 is about 50 to 200 L / min per 1 m ³ of volume inside the aerobic fermentation apparatus 120. Do.

In addition, in the actual site, by composting a large amount of sludge, partial solid-liquid separation may occur due to its own weight even after the water content is adjusted, so that the liquid may fall into the bottom of the aerobic fermentation apparatus 120, so that the bottom may be prepared. It is desirable to have a slope of about 2 to 5% and to collect the collected water with a cock.

Next, in the third step (S3), the sludge mixture of the aerobic fermentation apparatus 120 is introduced into the post-aging apparatus 130 to incubate and stabilize in aerobic state to complete the compost.

That is, when the microorganism reaches the moisture range in which it can be properly activated, it is necessary to stop the heating, and after that, it is necessary to pass the aging time of supplying only the appropriate amount of air, so that the high-temperature fermentation solids during the composting process according to an embodiment of the present invention. The post-boiling device 130 to ripen is a step of stabilizing the sludge compost fermented to a high temperature through a ripening step, but not heated, but must maintain aerobic state continuously. This period is about 5 to 6 days, after which the sludge composting process ends.

Next, in the fourth step (S4), the sludge mixture of the post-adjustment unit 130 is introduced into the sorting unit 140 to sort the swelling material from the sludge mixture by sieving, and then the composted sludge is located in the adjacent green farmland. The swelling material is sent to the solid-liquid separator 110 and recycled. At this time, the swelling material having a size of about 5 to 15mm is used to easily separate the swelling material from the final product.

Finally, in the fifth step (S5) to check the sludge of the storage tank 100, if there is sludge proceeds to the first step again, if there is no sludge is terminated. This operation is controlled by the controller 160.

In the present invention, the solid-liquid branching device 110, the aerobic fermentation device 120, the post-treatment device 130 and the sorting device 140 to operate the entire system except the on and off of the control device 160, etc. Arranged sequentially in an elliptical ring configured to infinitely circulate in a donut shape, and between each device is installed screw conveyors (111, 121, 131, 142) to be moved at regular intervals. In this case, the screw conveyors 111, 121, 131, and 142 simultaneously perform the functions of feeding and mixing. In addition, the moving speed of the screw conveyors (111, 121, 131, 142) is adjusted by the controller 160 to satisfy the residence time required by each device.

In addition, the odor generated in the entire composting process is collected and treated by the biofilter 50, wherein the filler inside the biofilter may be used by mixing the previously produced compost and swelling material.

When the sludge is drawn and treated using the sludge treatment apparatus and method of a small sewage treatment plant according to an embodiment of the present invention will be described through the experimental example Table 1 to minimize the re-release of phosphorus in the storage tank.

Storage period of sludge in storage tank Liquid / Solid Moisture content (%) Volume (L) Concentration (mg / L or mg / kg) T-P (mg) T-P (%) Long stayed sludge Liquid 96 0.85 9.2 7.82 45.4 elegance 4 0.15 1570 9.42 54.6 Recently Generated Sludge Liquid 98 0.77 26.4 20.33 40.1 elegance 2 0.23 6600 30.36 59.9

Table 1 shows the contents of phosphorus by measuring the total concentration of phosphorus in concentrated sludge and liquid sewage after solid-liquid separation of sludge that has been in the sludge storage tank for a long time and sludge that is newly generated and not old for a long time. ) And percentage (%). The content of phosphorus in old sludge is 7.87mg in liquid phase, 9.42mg in solid phase, and the ratio of liquid to solid phase is 45.4: 54.6%. In addition, the content of phosphorus in the recently produced sludge can be seen that the liquid phase is 20.33mg, the solid phase is 30.36mg, the ratio of the liquid phase to solid phase is 40.1: 59.9%.

That is, it shows that the phosphorus content of the sludge produced recently is higher than that of the sludge which has been retained for a long time, and when the sludge stays in the storage tank for a long time, it can be confirmed that phosphorus is re-released into the water treatment system. In addition, the phosphate contained in the concentrated sludge is periodically removed from the water treatment system to confirm the actual phosphorus removal in the water treatment system.

Although the present invention has been described in detail only with respect to specific examples described in the embodiments, it is apparent that various modifications and variations can be made by those skilled in the art within the scope of the present invention, and such variations and modifications also belong to the appended claims. Of course it is.

1 is a block diagram showing the overall configuration of a sludge treatment apparatus according to an embodiment of the present invention.

2 is a cross-sectional view schematically showing the solid-liquid separation device in one embodiment of the present invention.

3 is a graph showing the water content and the volume change of the concentrated sludge over time in the solid-liquid separation apparatus according to an embodiment of the present invention.

4 is a graph showing a change in moisture content according to the initial moisture content in one embodiment of the present invention.

5 is a graph showing the change in moisture content according to the size of the swelling material in the embodiment of the present invention.

6 is a flowchart showing a sludge treatment method according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: solid sludge 20: liquid sewage

100: storage tank 101: inflow pipe

102: outflow pipe 103: sludge inlet

110: solid-liquid separator 111, 121, 131, 141, 142: screw conveyor

112: floating valve 113: opening device

114: agitator 120: aerobic fermentation apparatus

122: heat source 130: rear housing device

140: sorting device 143: swelling material inlet

150: air pump 160: controller

170: biofilter 200: green farmland

Claims (14)

delete delete delete delete delete delete delete A first step of introducing the sludge of the storage tank into the solid-liquid separator and separating the solid phase and the liquid phase, then returning the liquid phase to the storage tank and mixing the solid phase with the swelling material to adjust the initial water content of the sludge to 60 to 70%; A second step of introducing the sludge mixture of the solid-liquid separator into the aerobic fermentation apparatus while fermenting while heating to a predetermined temperature in an aerobic state; A third step of introducing the sludge mixture of the aerobic fermentation apparatus into a post-preparation apparatus to incubate and stabilize in aerobic state to complete the compost; After the sludge mixture of the post-boiling device is introduced into the sorting device to separate the swelling material from the sludge mixture, the composted sludge is transferred to the adjacent green farmland, and the sorted swelling material is transferred to the solid-liquid separator and recycled. ; And A fifth step of checking whether or not there is sludge in the storage tank, if the sludge is present, proceeding to the first step again; Sludge treatment method of a small sewage treatment plant comprising a. The method of claim 8, Sludge treatment method of a small sewage treatment plant, characterized in that the aerobic fermentation device and the post-aging device is continuously supplied with the outside air to the air pump to maintain aerobic. The method of claim 8, In the solid-liquid separator in the first step, a floating valve is installed at the sludge interface to suck the liquid phase of the upper layer and return it to the bioreactor or the flow adjusting tank, and to discharge the sludge mixture in which the solid sludge and the swelling material are mixed. Sludge treatment method of a small sewage treatment plant characterized in that the switchgear is installed in the lower portion, a stirrer is installed inside to mix the solid sludge and the swelling material. The method of claim 8 or 10, Sludge treatment method of a small sewage treatment plant characterized in that the sludge introduced into the solid-liquid separator in the first step is suspended for 24 to 36 hours to separate the liquid phase and the solid phase. The method of claim 8, The aerobic fermentation apparatus in the second step is a sludge treatment method of a small sewage treatment plant characterized in that the sludge mixture is suspended for 8 to 12 days while maintaining the internal temperature at 50 to 55 ℃. The method according to any one of claims 8, 9, 10 or 12, The sludge treatment method is a sludge treatment method of a small sewage treatment plant, characterized in that the processing of the odor generated during the treatment process at the same time as the first to fourth stages by collecting the biofilter. The method according to any one of claims 8, 9, 10 or 12, Sludge treatment method of a small sewage treatment plant characterized in that a screw conveyor is installed between the solid-liquid separation device, aerobic fermentation device, post-aging device and the sorting device, respectively, to transport and stir the sludge mixture.

Images