JPH03207497A - Treatment of sewerage sludge - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application Field The present invention relates to a method for treating sewage sludge generated from domestic wastewater, industrial wastewater, and the like.

<Prior art> In order to improve people's health and hygiene management, sewage systems are being popularized in various regions. At sewage treatment plants, a large amount of sludge is generated as a result of sewage treatment, and although some sludge is used as fertilizer, the majority of the sludge is not used effectively and is disposed of in landfills after dewatering or in landfills after dewatering and incineration. It has been disposed of.

Although this sludge contains organic matter and has value as fuel, it is ultimately dumped due to its high moisture content and difficulty in handling. Establishment of more effective utilization technology is desired.

What is shown in Fig. 2 is an example of a general domestic sewage treatment facility, in order from the upstream side: a settling tank 50, a first settling tank 51.
, an aeration tank 53 using an air compressor 52, and a final sedimentation tank 54 are provided, and the initial sedimentation 55 and final sedimentation 56 are removed by a dehydrator 57.
Dehydrated cake (sludge) is obtained by dehydration. This dehydrated cake is generally either incinerated after adding a combustion improver or the like, or disposed of in a landfill.

The following methods have been proposed as methods for treating sludge or wastewater.

■ Japanese Patent Publication No. 61-59800 (method for processing surplus sludge using coke dry extinguishing equipment) The dehydrated sludge cake is blown into the system through the gas circulation path to treat excess sludge and improve coke cooling efficiency.

■ JP-A-61-271098 (Incineration treatment method for wastewater sludge) In this method, before incineration of wastewater sludge containing phosphorus, sludge and a calcium compound 'JIyJ (for example, CaCOa) are mixed to produce stable calcium phosphate. It is designed to prevent trouble and corrosion of the coals in incinerators, cyclones, etc.

■ Japanese Patent Publication No. 63-45639 (Method for treating organic waste liquid) This is an anaerobic and aerobic activated sludge method for waste liquid containing organic matter and phosphorus, in which concentrated primary settled sludge and concentrated surplus sludge are mixed at the same time or immediately after mixing. , iron salt compounds and slaked lime Ca (
OH) is added and then dehydrated to reduce the phosphorus concentration in the separated liquid during dehydration.

[Problems to be solved by this invention]

In the case of the conventional sludge treatment method as described above, there are the following problems.

(i) Landfill disposal law (b) There is a possibility of groundwater contamination.

(Explanation) It is difficult to secure a landfill site.

(c) Useful ingredients are not utilized efficiently.

(11) Incineration disposal method (b) Equipment costs are high.

(Mouth) Running costs are high.

(c) A certain amount of useful material is not used as a resource.

(ni) Use of coke dry fire extinguishing equipment It is difficult to process large quantities due to the influence of coke quality.

Conventional sludge treatment methods have the above-mentioned problems: ■ They are unhygienic. It can be said that the development of a treatment method for sewage sludge that satisfies the following conditions: ■It is inexpensive; and ■It can be used effectively as a resource.

This invention was made in view of these circumstances,
The purpose is to provide a method for treating sewage sludge that can hygienically and inexpensively treat sludge after sewage treatment, and that can completely and reuse a large amount of useful substances as resources.

[Means to solve the problem]

As shown in FIG. 1, in the present invention, quicklime CaO is added to a dehydrated cake (sludge) 2 discharged from a sewage treatment facility Oi1 such as domestic sewage, and the mixture is kneaded by a kneader 3.
In the hydration reaction of quicklime and the reaction heat during hydration, the heat-treated dust 4 is heated and dried, and this heat-treated dust 4 is used as a part of the sintering raw material 6 of the sintering equipment 5.

The sintering raw materials consist of iron ore 7, limestone 8, and coke 9, and after adding heat-treated dust 4 to these, they are mixed in a kneader 1.
The sintered ore 12 mixed in the blast furnace 1 and sintered in the sintering machine 11 is
Charge to 3.

Generally used equipment can be used for the sewage treatment equipment l and the sintering equipment m5.

<Function> (1) By kneading sludge and quicklime, CaO +
The water content in the sludge is reduced by the hydration reaction of HzO → Ca(OH)z+ Qkcal, and excess water is evaporated due to the reaction heat during hydration, making it possible to heat and dry the sludge without a special heating source. At the same time, the bacteria are also killed by heating.

(j1) By using heat-treated dust as a sintering raw material, slaked lime Ca (OH) z is used as a part of limestone, and the amount of limestone used can be reduced. In addition, slaked lime acts as a granulating agent for the fine powder raw material, improving productivity in the sintering process.

(iii) The slaked lime content in the heat-treated dust improves the combustibility of coke, and the organic content becomes part of coke powder by burning, thereby reducing the coke consumption for sintering.

The mixing ratio of sludge and quicklime is appropriately determined from the viewpoint of calorific value, economical efficiency, etc., but it is preferable that the weight ratio is 1=1.

In addition, the addition ratio of heat-treated dust to the sintering raw material is 25%.
The following is true. In the production of sintered ore, not only iron ore but also limestone is used as a raw material in order to make it a self-soluble sintered ore, and in the present invention, the slaked lime content in the heat-treated dust is used as part of the limestone. If more than 25% is added, the lime content in the raw material will be excessive and the quality of the sintered ore will deteriorate.

Practical example> This is a case where quicklime C is added to the dehydrated cake 2 from the sewage treatment equipment 1.
This is an example in which aO was mixed at a weight ratio of 1:l and the resulting heat-treated dust 4 was sintered in a sintering equipment 5, and the results shown in the following table were obtained.

Table 1 Heat treatment results Table 2 Results of sintering heat treated dust From these tables, it is possible to heat dry and sterilize sludge, improve production rate, and reduce coke consumption and limestone consumption in the sintering process. I understand that.

A trial calculation of the amount of sewage sludge that can be treated is as follows.

■Assumed amount of crude steel 7,000 KT/year Required amount of sintered ore for integrated steelworks: 800 (KT/month) Required amount of sintering raw material: 890 (KT/month) (800 x
1/0.9) Heat treatment dust addition amount: 45 [κT/month] (890X5
%) ■Sludge treatment amount 45κTXI/1.8 (yield) = 2 5 (K
T/month]■Population that can be treated [Effects of the invention] As mentioned above, the method for treating sewage sludge according to this invention is as follows:
By mixing quicklime with sludge to obtain heat-treated dust and using this heat-treated dust as part of the sintering raw material, the sludge can be heated to dry and sterilized, and the slaked lime content and organic components in the heat-treated dust can be reduced. It is possible to improve the production rate, reduce the coke consumption rate and the amount of limestone used, and the sludge after sewage treatment can be treated hygienically and inexpensively, and the useful portion can be completely and in large quantities used as a resource. It can be effectively reused and rendered harmless.

[Brief explanation of drawings]

FIG. 1 is a system flow diagram showing a sewage sludge treatment method according to the present invention, and FIG. 2 is a system flow diagram of a general sewage treatment facility. 1... Sewage treatment equipment, 2... Dehydrated cake (sludge) 3
...Kneading machine, 4...Heating treatment dust 5...
Sintering equipment, 6...Sintering raw material 7...Iron ore,
8... Limestone 9... Coke, ■0...
Kneader 11...Sintering machine, 12...Sintered ore 13
...blast furnace

Claims (1)

[Claims] (1) Treatment of sewage sludge characterized by mixing quicklime with sludge to obtain heat-treated dust through hydration reaction and reaction heat during hydration, and using this heat-treated dust as part of the sintering raw material. Method.