JPH0126757B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a domestic septic tank.

(Prior Art) Household septic tanks primarily process human waste.

In recent years, household septic tanks that use various aerobic bacteria have been developed, but their processing capacity is very low and they are only able to treat a small portion of the human waste, making it difficult to judge the quality of the treated water. At present, it is difficult to hope for any long-term improvement. Furthermore, in conventional household septic tanks, surplus sludge is generated, and this surplus sludge must be periodically removed from the septic tank, making its management troublesome. Furthermore, since the suspended suspended solids in the treated water, that is, the SS content (suspended particles of 2 mm or less), are not removed, the amount of solid organic matter contained in the treated water is large, and it cannot be said that the treatment is complete.

(Problems to be Solved by the Invention) The present invention has been made to solve the problems of the prior art described above. The purpose of the present invention is to provide a septic tank that is simple in structure and extremely economical.

(Means for Solving the Problems) The household septic tank of the present invention includes a treatment tank, an inner tank provided in the treatment tank and having an opening that fluidly communicates with the treatment tank, and a an introduction part for introducing sewage; an aeration device for supplying air to at least the inner tank to agitate and aerate the sludge; and a discharge part for discharging treated water from the treatment tank to the outside of the treatment tank; a net-like body which is provided in a state surrounding the inner tank in the treatment tank and allows microorganisms to adhere and multiply to form a microbial layer, and the net-like body is made of synthetic resin. It is formed by assembling ring-shaped filaments radially around a core material made of synthetic resin in a lattice pattern, and furthermore, all of the treated water is After passing through the microorganism layer, it is configured to be discharged from the discharge section to the outside of the processing tank.

(Function) When sewage is introduced into the septic tank of the present invention having the above-described configuration, the sewage is agitated by air from the aeration tube and undergoes the purification action of the activated sludge.

Here, various types of bacteria, protozoa, micrometazoa, etc. present in the wastewater undergoing purification adhere to the reticulate body and form a microbial layer on the reticulate body. The shape of the string-like body consisting of ring-like thread-like bodies growing densely in a radial manner around the core material and the structure of the network body in which the string-like bodies are combined in a lattice shape are very favorable for the formation of a microbial layer.

In addition, the microbial layer formed on each string-like body consists of aerobic bacteria in the radially outer part, where there is more chance of contact with dissolved oxygen, and radially inner part, where there is less chance of contact with dissolved oxygen. has a structure in which facultative anaerobes exist, and the food chain interaction between these aerobic bacteria and facultative anaerobes causes the microbial layer itself, that is, activated sludge, to be digested, resulting in the generation of surplus sludge. can be prevented.

Furthermore, all treated water is discharged from the discharge section to the outside of the treatment tank after passing through the microbial layer, so SS (suspended solids) contained in the treated water passes through the microbial layer. captured when In other words, the microbial layer acts as a filtration membrane for SS content, making it possible to discharge treated water with extremely low SS content.

(Effects of the Invention) As is clear from the above-described configuration and operation, the present invention provides a household septic tank that does not generate surplus sludge and can discharge treated water with extremely low SS content. Ru. Therefore, it becomes possible to discharge treated water into a river, thereby making it possible to economically and efficiently treat domestic wastewater in areas without complete sewerage systems.

(Example) Examples of the household septic tank of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the household septic tank of the present invention, which includes a treatment tank 2 having a discharge section 1 for discharging treated water to the outside, and a treatment tank installed approximately in the center of the treatment tank. an inner tank 5 having an opening 4 in fluid communication with the treatment tank 2; a support 8 for fixing a dense mesh or fabric 7 (FIG. 4) around the outer circumference of the inner tank; , an internal air diffuser 9 that supplies air to the bottom of the inner tank;
Inside the processing tank 1 formed between the inner tank and the support part 8
It is composed of an external aeration pipe or external aeration device 10 that supplies air to the bottom 3 of the tank 2, and an inflow pipe or introduction section 11 that introduces wastewater into the interior of the inner tank.

In this embodiment, the inner tank is provided with its lower end in contact with the bottom 3 of the processing tank and has an opening 4 that communicates with the inside 12 of the processing tank. A spacing can also be provided between the bottom 3 of the treatment tank and in this case the opening 4 can also be omitted.

In the illustrated embodiment, there are also two sets of internal and external diffuser pipes 9 each branching from a common branch pipe.
and 10 are provided, but the number and shape of these diffuser pipes can be selected as appropriate.

Various shapes can be used for the net-like body, but a string-like body formed by densely growing annular thread-like bodies made of synthetic resin radially around a core material 20 made of synthetic resin as shown in FIG. It is preferable to use a net-like body 7 shown in FIG. 4, which is formed by combining 6 in a lattice shape into a net shape. The network thus formed has the excellent property of easily trapping microorganisms in and around it, forming a stable microbial layer. In this example, the core material 20 is a wire 21.
When it is knitted around the center and later stretched around the net-like body, the tension is received by this wire and is not applied to the synthetic resin string-like body.

Next, the operation of the septic tank of the present invention will be explained.

The wastewater flowing into the inner tank 5 from the inflow pipe 11 is rapidly stirred and aerated inside the inner tank by compressed air jetted from the internal aeration pipe 9. At this time, solid matter such as feces in the sewage is crushed and dispersed, and at the same time, organic substrates in the sewage are decomposed by activated sludge that grows in the sewage. The agitated and aerated wastewater is sent from the inner tank to the treatment tank interior 12 through the opening 4 according to the amount of wastewater flowing in from the inflow pipe 11. Domestic wastewater is not discharged continuously but intermittently, so if the inflow of wastewater from the inflow pipe 11 is stopped, the solids remaining inside the inner tank are further crushed and dispersed. At the same time, it is purified by activated sludge.

The sewage flowing into the treatment tank interior 12 through the opening 4 is agitated by compressed air blown out from the external diffuser pipe 10 and is subjected to the purifying action of the activated sludge. Here, various types of bacteria, protozoa, micrometazoans, etc. existing in the wastewater undergoing purification adhere to the net-like body 7 and form a microbial layer on the net-like body. The microorganism layer formed here has facultative anaerobic bacteria on the radially inner side of the string-like body 6, and an aftergrowth containing aerobic bacteria on the radially outer side thereof, The screen action of the net captures suspended solids in the treated water passing through this microbial layer and removes them from the treated water. Since it also digests itself, it can also digest activated sludge. In particular _, denitrifying bacteria, which are facultative anaerobes, occur inside _the network where microorganisms adhere and proliferate. Denitrification is possible because it is configured so that denitrifying bacteria can change the substance into nitrogen gas (N ₂ ). Furthermore, bacteria,
Since it can coexist with protozoa and micrometazoa from lower to higher levels, most of the phosphorus is consumed by activity and fission energy, and is finally reduced to an acceptable SS content or higher levels of organisms.

By discharging the treated water to the outside through the microbial layer formed in the network, the SS content in the treated water can be completely removed, resulting in highly transparent treated water with a low BOD value. Can be discharged.

As described above, according to the present invention, it is possible to prevent clogging of the network and the microbial layer by the digestive function of the microbial layer itself, and to suppress the increase in activated sludge in the treatment tank. This provides a septic tank that is easy to maintain and does not generate excess sludge, which inevitably occurs in the normal activated sludge method.

If the degree of contamination of the inflowing raw sewage water is high, install multiple nets on the outside of the inner tank or install a third
By arranging a plurality of string-like bodies shown in the figure between the inner tank and the net-like body, the purification performance can be increased. Note that instead of a high-density net-like body made of string-like bodies, a cloth-like body or a filter cloth having a large number of protrusions or ring-like filaments on the surface can also be used.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the septic tank according to the present invention, FIG. 2 is a cutaway plan view of FIG. 1, FIG. 3 is a side view of the string-like body, and FIG. 4 is a side view of the string-like body of FIG. FIG. 3 is a front view of the constructed net-like body. DESCRIPTION OF SYMBOLS 1... Discharge part, 2... Processing tank, 3... Bottom of processing tank, 4... Opening, 5... Inner tank, 6... String-like body, 7... Net-like body or cloth-like body, 8 ...Support part,
9, 10... Diffusion pipe, 11... Introduction part, 12...
Inside the treatment tank, 13... Exhaust pipe, 20... Core material, 2
1...Wire.

Claims (1)

[Claims] 1 a processing tank; an inner tank provided in the processing tank and having an opening that fluidly communicates with the processing tank;
an introduction section for introducing sewage into the inner tank; an aeration device for supplying air to at least the inner tank to agitate and aerate the sludge; and an aeration device for discharging treated water from the treatment tank to the outside of the treatment tank. A domestic septic tank comprising: a discharge part; and a net-like body that is provided in the treatment tank to surround the inner tank and to which microorganisms can adhere and multiply to form a microorganism layer. The net-like body is formed by assembling string-like bodies in a lattice shape, which are formed by densely growing ring-like filament bodies made of synthetic resin in a radial manner around a core material also made of synthetic resin. A household septic tank, further comprising a structure in which all of the treated water passes through the microbial layer and then is discharged from the discharge section to the outside of the treatment tank.