JPS5861890A - Treatment for sewage - Google Patents

Abstract

PURPOSE:To treat law night soil and the sludge in a purifying tank simultaneously by settling and separating the activated sludge in a liquid mixture after aeration of the night soil, returning part thereof to the aeration treatment and aerating the sludge in an inflow purifying tank and the excess sludge mixture. CONSTITUTION:After law night soil receives pretreatments such as settling in a pretreating tank 1, the night soil is stored in a storage tank 2, from which the same is introduced into a tank 3 for primary treatment where the night soil receives an anaerobic or aerobic digestion treatment. The liquid after the primary treatment is fed together with diluting water to a tank 4 for secondary treatment, where the liquid receives secondary treatment by aeration and is fed into a settling tank 5 so that the liquid is subjected to the sepn. of activated sludge. The sludge of the purifying tank treated together with the low night soil is treated in a pretreatment tank 6, thereafter the sludge is stored in a storage tank 7, from which the sludge is fed into an aerating tank 8. In the tank 8, the sludge of the purifying tank and the activated sludge drawn from the tank 5 are mixed, and the mixture is aerated for, for example, about 3 days.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a sewage treatment method that simultaneously treats human waste and septic tank sludge.

The absolute amount of human waste septic tank sludge delivered to human waste removal sites is increasing year by year as the number of people using water washing increases. According to current structural standards, septic tank sludge undergoes pre-treatment and is then stored, after which it is heated with raw human waste.
It is now mixed and processed at human waste treatment facilities. However, septic tank sludge has a relatively low content of BOD and other substances compared to raw human waste, and the operating conditions of human waste treatment facilities tend to be low-load.The properties of septic tank sludge vary depending on the form of the septic tank. Since the clothes are different, it is inevitable that the situation at the human waste treatment facility will fluctuate and the quality of the treated water will become unstable.

An object of the present invention is to provide a sewage treatment method that can efficiently treat septic tank sludge while operating a human waste treatment facility stably under a sewage system.

Next, an example of the steps of the method of this invention will be explained with reference to the drawings. In the figure, the raw human waste to be treated is first treated in the front Asahi tank 1, then all the pre-treatment substances such as Isin are stored in the storage tank 2, and then introduced into the primary treatment 4113 at an appropriate flow rate. Here, they undergo anaerobic or aerobic digestion. After this primary treatment, the liquid is sent to the secondary treatment tank 4 along with an appropriate amount of dilution water, where it undergoes secondary treatment by aeration, and then sent to the settling tank 5 where activated sludge is separated. .

The supernatant water is then discharged as treated water, and a portion of the activated sludge is returned to the secondary treatment tank 4 as return sludge.

Since the above processing is the same as that of general human waste processing, detailed explanation thereof will be omitted.

On the other hand, the septic tank sludge that is treated together with human waste is pretreated in a pretreatment tank 6, then stored in a storage tank 7, and sent to the next aeration storage tank 8. In this aeration storage tank 8, the septic tank sludge sent from the storage Wi7 and the activated sludge pulled out from the settling tank 5 are mixed, and this mixture is kept for a relatively long time, for example, about 3 days. I'm exposed. The activated sludge immediately after being pulled out from the settling tank 7 has high anastomological activity, so the septic tank sludge mixed with this activated sludge is purified while being aerated, and the flocculation and sedimentation properties are reduced. Generates sludge with excellent quality.

After being aerated for a predetermined period of time in the aeration storage tank 8, the sludge from the septic tank is sent to the shrinkage tank 9, where the sludge is shrunk. The thickened sludge is further dehydrated in the next dewatering step 61110, and then discharged as a dehydrated cake. on the other hand,
- The separated liquid separated from the sludge in the shrinking tank 9 and the dehydrator 10 are both introduced into the secondary treatment tank 4. This separated liquid is S
Not only does it contain almost no S, but also because it has been sufficiently aerated in the aeration storage tank 8, its water quality is extremely low in organic matter. However, it does not interfere with the treatment of human waste that has undergone the primary filtration, and has little influence on fluctuations in the load.

The water quality analysis values of the fresh human waste and septic tank sludge subjected to the experiment conducted according to the process shown in Figure 1 are shown in Table 1 on the next page, together with those of the excess sludge extracted from the settling tank 5.

The ratio of 9 septic tank sludge and excess sludge shown in ttagl@ is 3:10.
The water quality of the separated liquid obtained by flowing it into the sludge storage tank 8 and aerating it for 3 days was then separated from the sludge.
Shown in the table.

Table 1 #12 Table 21! As is clear from &, the water quality of the separated liquid introduced into the secondary treatment tank 4 is extremely good, and this water quality is not affected by the properties of the inflowing septic tank sludge, and K is almost constant. Therefore, the series of human waste treatment conditions are not influenced by the conditions on the septic tank sludge side, and stable treatment can be performed at all times.

As described above, in the method of this invention, the septic tank sludge is
Unlike the conventional method in which human waste is introduced into the primary treatment step of the human waste treatment process, the raw human waste is mixed with surplus sludge obtained in the human waste treatment process, and then passed through an aeration chamber in advance. The sludge is separated and the separated liquid is introduced into the aeration stage of the human waste treatment process. Even if the amount of inflow of septic tank sludge or its vk condition changes over time, the human waste treatment process will not be affected by this, and a stable treated water quality will always be ensured.

[Brief explanation of the drawing]

The figure is a flow sheet showing an example of the steps of the method of this invention. 1... Pretreatment tank, 2... Storage tank, 6... Primary treatment hinoki, 4... Secondary treatment tank, 5... Sedimentation tank, 6... Pretreatment tank, 7 ...Storage tank, 8...Flash storage tank, 9.
... desalination tank, 1° ... dehydrator.

Claims (2)

[Claims] (1) The aeration process in which the human waste is aerated, the precipitation process in which the activated sludge contained in the heated mixture is separated by precipitation, and the activated sludge is separated and activated. A step in which a part of the sludge is returned to the above-mentioned flash relief and the remainder is taken out as surplus sludge, a step in which the mixture of the inflow septic tank sludge and the above-mentioned surplus sludge is treated with air, and A sewage treatment method comprising the steps of separating m-purified matter from the above-mentioned mixture and sending it to the above-mentioned flash treatment facility. (2) The sewage treatment method according to claim 1, wherein the mixing ratio of the inflow septic tank sludge and the excess sludge is about s=1.