JP2010253437A - Method for treating organic wastewater and chemical used for the method for treating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biological treatment method for organic wastewater which can achieve further improvement of water quality of treated water, improvement of settleability of sludge to be generated, securement of stability of treatment, and improvement of dewaterability of excess sludge in biological treatment of organic wastewater, and can provide an effective use of incinerated ash of organic wastes such as excess sludge and food residues. <P>SOLUTION: The method for treating organic wastewater, which biologically treats the organic wastewater using the incinerated ash obtained by incinerating the organic wastes, includes at least any incinerated ash addition step of making the incinerated ash added to the organic wastewater raw water, adding the incinerated ash to a biological reaction tank, or adding the incinerated ash to returned sludge. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a biological treatment method of water to be treated containing an organic pollutant component (hereinafter also referred to as organic wastewater or raw water), more specifically, incineration ash of organic waste can be used effectively, The present invention relates to a biological treatment method capable of achieving improvements in the quality of treated water after biological treatment, improvement in sludge settling, stabilization of treatment, improvement in dewaterability of excess sludge, and the like for various organic wastewater.

  Industrial wastewater such as papermaking wastewater, chemical factory wastewater, dyeing wastewater, and food manufacturing wastewater contains a lot of organic pollutants, but the treatment of these wastewater (called organic wastewater) is generally microbial. Is carried out by biological treatment to decompose organic pollutant components. Examples of biological treatment methods include activated sludge method, catalytic oxidation method, fixed bed biological treatment method, fluid carrier activated sludge method, anaerobic digestion (methane fermentation method) and the like. These biological treatment methods all utilize the biological activities of microorganisms, and thus various studies have been made, but it is difficult to increase the treatment efficiency, and further studies are required. At the same time, there were the following problems specific to biological treatment. For example, an activated sludge method widely used in sewage treatment, factory wastewater treatment, etc., 50 to 70% of the BOD decomposed by the method is consumed as microbial maintenance energy, but the remaining 30 to 30%. Since 50% is used for the growth of bacterial cells, the amount of sludge gradually increases. Since the sludge increased beyond the amount required for the treatment needs to be solid-liquid separated and removed as excess sludge, the treatment of a large amount of excess sludge generated in biological treatment is always a problem. The amount of surplus sludge generated as secondary waste has been increasing in recent years, and various volume reduction methods have been tried. However, at present, it is difficult to completely eliminate surplus sludge by an economical method. is there. On the other hand, when surplus sludge is disposed of, there is a problem of secondary pollution, and a large amount of surplus sludge is serious. In recent years, awareness of environmental conservation has increased, and its importance has attracted attention. Further improvement of treated water quality after biological treatment and ensuring its stability are also important issues.

  As the treatment of excess sludge, after sludge is dehydrated, it is often landfilled as it is or after incineration. On the other hand, various methods for effectively using the incineration ash of excess sludge generated in large quantities have been studied. For example, after granulating and molding the sewage sludge incineration ash generated in the sewage sludge treatment facility, the molded product is dried and fired to form an aggregate (for example, see Patent Document 1), incineration ash such as sludge incineration ash, It has been proposed to use incinerated ash as various product raw materials, such as mixing organic sludge such as activated sludge treatment to make a soil improvement material (see, for example, Patent Document 2).

  On the other hand, along with the development of industry and life in recent years, large amounts of organic waste from agriculture, livestock, fisheries, forestry, etc. have been generated in a concentrated manner. The disposal of a large amount of incinerated ash generated after processing these materials has also become a problem. On the other hand, it has been proposed to use the melted product as a microorganism adhesion carrier used in wastewater treatment (see, for example, Patent Document 3).

JP 2004-67493 A Japanese Patent Laid-Open No. 9-111238 JP 2000-107787 A

  Therefore, an object of the present invention is to provide a biological material that can further improve the quality of treated water in biological treatment of organic wastewater, improve the sedimentation of generated sludge, ensure the stability of treatment, and improve the dewaterability of excess sludge. It is to provide a processing method. Another object of the present invention is to provide a more economical and better biological treatment method for organic wastewater and to provide an effective use of incineration ash of organic waste such as excess sludge and food residues. It also contributes to the treatment of these organic wastes.

  The above object is achieved by the present invention described below. That is, the present invention is an organic wastewater treatment method for biologically treating organic wastewater using incineration ash obtained by incineration of organic waste, and the incineration ash is added to the organic wastewater. It is characterized by having an incineration ash addition step of at least one of using the raw water as raw water, adding the incineration ash to a biological reaction tank, or adding the incineration ash to return sludge Provide a method for treating organic wastewater. Furthermore, the present invention provides a chemical for wastewater treatment, which is a chemical used in the method for treating organic wastewater, comprising incinerated ash obtained by incineration of organic waste as a main component. To do.

  According to the present invention, there is provided a biological treatment method capable of realizing further improvement of treated water quality in biological treatment of organic wastewater, improvement of settling property of generated sludge, ensuring treatment stability, and improvement of dewatering property of excess sludge. Provided. ADVANTAGE OF THE INVENTION According to this invention, the more economical and better biological treatment method of organic waste water is implement | achieved, and the way of the effective utilization of the incineration ash of organic waste is provided.

  The present invention will be described in detail with reference to preferred embodiments of the present invention. As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors have either treated incineration ash obtained by incineration of organic waste during the biological treatment of organic wastewater. It was found that by adding at this stage, the sedimentation property of the generated sludge is improved, the solid-liquid separation is performed in a good state, and at the same time, the quality of the treated water is improved. Specifically, it has been found that it is effective to add incineration ash in at least one of the following stages. In other words, at least the incineration ash added to the organic waste water is used as raw water, the incineration ash is added to the biological reaction tank, or the incineration ash is added to the return sludge. And Of course, you may make it add incineration ash combining these. The inventors of the present invention have confirmed that, by configuring as described above, the stability of the treatment is ensured and good biological treatment can be performed continuously. It was also found that the dewaterability of excess sludge was improved. Improvement of the dewaterability of excess sludge results in an improvement in the economic efficiency of the treatment of excess sludge that is incinerated after drying.

  Regarding the reason why the above-described excellent effect can be obtained by adding incineration ash obtained by incineration of organic waste at any stage of treatment and using it for biological treatment of organic wastewater, the present inventor Think as follows. In the examination process, for example, when biologically treating various factory effluents such as paper effluents, chemical factory effluents, dyeing effluents, food manufacturing effluents, etc., organic pollutants and inorganic components contained in these effluents It was confirmed that the balance was not necessarily in a state suitable for biological treatment. That is, when it comes to inorganic components, the main constituent elements of microorganisms such as nitrogen and phosphorus may be deficient in the wastewater, but in that case, the biological treatment efficiency is clearly inferior. . For this reason, such waste water lacking nitrogen or phosphorus is usually treated artificially by adding nitrogen and phosphorus to compensate for the shortage. According to further studies by the present inventors, not only the above, but also necessary to constitute a living organism such as sodium, potassium, calcium, magnesium, chloride ion, sulfur, or iron, zinc, copper, aluminum, etc. There is a wastewater with a rare composition or a biased composition. However, at present, such components are not particularly considered for the effects on biological treatment. In order to improve the efficiency of biological treatment, the present inventors have considered that the presence of these components is not negligible, and have conducted detailed studies including this point, and have reached the present invention.

  First of all, the inventors of the present invention have experience that activated sludge generated in wastewater treatment that is considered to have a small amount of inorganic components has poor sedimentation and dehydration properties, and may have difficulty in ensuring the stability of the treated water. We focused on the fact that there are many cases. Possible causes of the deterioration of sludge sedimentation include the case where filamentous bacteria grow abnormally and the case where the viscosity of activated sludge increases. Conventionally, the above-mentioned phenomenon has frequently occurred in wastewater with insufficient nutrients.

  Filamentous bacteria form a filamentous body and have a large body surface area. As a result, it is thought that the absorption rate of low-concentration nutrients is increased. The present inventors presume that there is a similar tendency not only for absorption of organic components as nutrients but also for inorganic components as listed above. That is, it is considered that the growth rate of filamentous bacteria is faster than that of floc-forming bacteria under the condition of lacking nutrients regardless of inorganic / organic. As a result, for example, in the activated sludge method, filamentous bacteria in the activated sludge become the dominant species, and abnormal growth of the filamentous bacteria occurs, which contributes to poor sedimentation of the sludge. It is thought that.

  On the other hand, the clear mechanism of the increase in the viscosity of activated sludge is unknown, but as described below, it is thought that this is also due to the nutritional balance of the wastewater (raw water) to be treated. Bacteria are generally known to actively produce extracorporeal polymers to protect bacterial cells when placed in an oligotrophic state. From this, it is considered that the mineral nutrition balance of the raw water is lost or insufficient, which causes an increase in the viscosity of the activated sludge.

  Based on the above knowledge, the present inventors are inexpensive and easy to obtain, and are suitable for biological treatment by adding to the wastewater the balance between organic pollutant components and inorganic components in various organic wastewaters having different properties. We thought that it would be very useful if there was a material that could be made, and conducted various studies. Specifically, from the standpoint of improving the efficiency of biological treatment, we examined whether various materials are effective as additive materials. As a result, the incineration ash of organic waste was found to be an optimum material for achieving the object of the present invention, and the present invention was achieved. According to the study by the present inventors, sewage sludge, surplus sludge generated from biological treatment of industrial wastewater, dredging, food residues, agricultural waste, livestock / poultry manure, livestock waste, aquatic waste, forest waste, etc. Any organic waste incineration ash can achieve the effects of the present invention. In particular, the effects of the present invention can be obtained more significantly by using incineration ash of sewage sludge and incineration ash of surplus sludge generated from biological wastewater treatment equipment.

  As shown below, in activated sludge microorganisms used for biological treatment, inorganic components constituting the body of wastewater treatment microorganisms are contained in a very balanced manner, which is suitable for achieving the object of the present invention. Table 1 shows an analysis example of the composition of sewage sludge incineration ash, but it contains not only phosphorus but also trace components that are considered necessary for maintaining the life of microorganisms in a well-balanced manner. According to the study by the present inventors, it is preferable that 100 g of incinerated ash contains at least 5 g of phosphorus in terms of oxide. As other components, those containing at least potassium, calcium, sodium, magnesium, manganese, iron, zinc, copper and the like, particularly those containing potassium, calcium and magnesium are preferred. Since these components are contained in a well-balanced manner in the incineration ash of organic waste, any of them can be preferably used, but in particular, sewage sludge, surplus sludge generated from biological treatment of industrial wastewater, food residues, etc. It is preferable to use incineration ash of organic waste. About potassium, calcium, sodium, and magnesium, it is preferable that at least 1 g or more is contained in 100 g of incinerated ash in terms of oxide. Moreover, about manganese, iron, zinc, and copper, it is preferable that at least 0.1g or more is contained in 100g of incineration ash in conversion of an oxide.

  The present invention is characterized in that incineration ash of organic waste is added at any stage of biological treatment, and the incinerated ash is used for biological treatment. In the present invention, when using the incinerated ash as described above, it is not particularly necessary to perform pretreatment such as pulverization of the incinerated ash, particle size adjustment, or extraction of organic substances, and they can be used as they are. In other words, it can be said that the present invention has made it possible to provide a method for using organic waste at a very low cost. However, when incineration ash of organic waste is obtained, depending on the form of organic waste, its handling property, transportability, etc. may be inferior. What is necessary is just to carry out the sieving of the foreign substance of a particle size, the drying operation of a water | moisture content, etc.

  The biological treatment method used in the present invention is not limited to the activated sludge method, but uses a biological activity of microorganisms, such as a catalytic oxidation method, a fixed bed biological treatment method, a fluidized carrier activated sludge method, or an anaerobic digestion (methane fermentation method). Any of them may be used.

  Examples of organic wastewater to which the effect of the present invention is applicable and to which the biological treatment method of the present invention can be applied include all organic wastewater capable of biological treatment. Especially, pulp and paper factory wastewater, wastepaper recycling factory wastewater, petrochemical industry wastewater, organic synthetic chemical factory wastewater, fat and oil chemical wastewater, pharmaceutical and pharmaceutical intermediate wastewater, textile industry wastewater, dyeing wastewater, scouring wastewater, metal surface treatment Degreasing wastewater, food production wastewater, papermaking wastewater or chemical factory wastewater. Among these, especially when applied to food production effluents such as confectionery / bread effluent, liquor effluent, beverage effluent, dairy effluent, noodle effluent, tofu effluent, prepared food / frozen food effluent, etc. High effect is obtained.

  The amount of incineration ash of organic waste to the organic wastewater as described above varies depending on the organic wastewater to be treated, but continuously adds 2 to 1,000 mg / l to the wastewater amount, It is effective to treat this as raw water. However, the present invention is not limited to this, and it is also effective to add temporarily for the purpose of improving these when, for example, sedimentation failure occurs or the quality of treated water deteriorates. In this case, for example, it is effective to add about 100 to 3,000 mg / l with respect to the amount of drainage at a time.

Next, the present invention will be described in more detail with reference to examples and comparative examples of the present invention.
<Examples 1 and 2 and Comparative Example 1>
Three series of activated sludge test devices with an aeration tank capacity of 5 L and a sedimentation tank capacity of 3 L were prepared, and the wastewater recycling wastewater was treated with 20 L / day water continuously for each series. At that time, the treatment test was started by adding sewage activated sludge as seed sludge to each aeration tank so as to be 2,000 mg / l. The average water quality of the precipitation-treated water of the used paper recycled wastewater used in the test was pH = 6.7, SS = 25 mg / l, COD = 130 mg / l, BOD = 180 mg / l.

  One series of the above was continuously added as sewage sludge incineration ash to 10 mg / l with respect to the amount of treated wastewater, and this was treated as raw water to give Example 1. In addition, another series is continuously added to forest waste incinerated ash from incineration of thinned wood, tree branches, etc. so that the treated wastewater becomes 10 mg / l, and this is treated as raw water. Example 2 was adopted. The remaining one series was treated as it was without adding incineration ash, and Comparative Example 1 was obtained. And processing was continued for 2 months about any series. The water quality of the treated water obtained after 2 months is shown in Table-2.

  As shown in Table 2, with respect to the pH, SS, and BOD of each treated water, there was no significant difference in measurement results between Examples 1 and 2 and Comparative Example 1. However, the COD of each treated water was 18 mg / l in the treatment of Example 1 and 19 mg / l in the treatment of Example 2, whereas it was 39 mg / l in the treatment of Comparative Example 1, which depends on the example. The result of treatment was about 20 mg / l better and it was confirmed that there was a significant difference. In addition, SVI, which is a sedimentation index of activated sludge, showed good sedimentation properties of 120 in the treatment of Example 1 and 110 in the treatment of Example 2, but 330 and poor sedimentation state in the treatment of the comparative example. It was confirmed that Furthermore, when the viscosity of the mixed liquid of activated sludge and raw water in the aeration tank was measured with a rotary viscometer, it was 3 cp in the treatments of Examples 1 and 2, whereas it was 8 cp in the treatment of Comparative Example 1. Yes, the viscosity of the activated sludge mixed solution of the comparative example showed a high value, and it was confirmed that there was a clear significant difference. The difference in the sedimentation index SVI between the example and the comparative example is considered to be caused by the difference in the viscosity of the activated sludge. The MLSS concentration of the activated sludge mixed solution in the aeration tank was measured after adjusting the concentration to 5,000 mg / l in both Examples 1 and 2 and Comparative Example 1.

<Example 3 and Comparative Example 2>
Two series of the same activated sludge test apparatus as used in Example 1 and the like were prepared, and the same test was performed with the treatment target being drainage from a beverage manufacturing factory. In Example 3 and Comparative Example 2, sewage treatment activated sludge was added to the aeration tank as seed sludge so as to be 4,000 mg / l. The average water quality of the beverage factory waste water used for the test was pH = 6.2, SS = 250 mg / l, COD = 880 mg / l, BOD = 1,750 mg / l.

  At the time of treatment, in the series of Comparative Example 2, 5% of raw water BOD was continuously added with urea as nitrogen, and 1% of raw water BOD was continuously added with phosphoric acid as phosphorus. On the other hand, in the series of Example 3, only 5% of raw water BOD was continuously added using urea as nitrogen, and phosphorus was not added. Instead, activated sludge generated from the wastewater treatment facility of liquor manufacturing plant was used. The incineration ash of excess sludge was processed while continuously adding 50 mg / l to the amount of waste water. And the water quality and sludge property of the treated water obtained at the time of 50 days after the start of treatment are shown in Table-3.

From Table-3, in process water quality, a big difference was not recognized by Example 3 and the comparative example 2 about SS and BOD. However, the COD of each treated water was 22 mg / l in the treatment of Example 3, whereas it was 29 mg / l in the treatment of Comparative Example 2, and the treatment of Example 3 was 7 mg / l lower. It was. Thus, there was a clear significant difference in the properties of the treated water obtained by the treatment between the example and the comparative example, and better results were obtained with the treatment of the example. Further, in the SVI of the sludge sedimentation index, the treatment of Example 3 showed a good sedimentation value of 80, whereas the treatment of Comparative Example 2 was in a very poor sedimentation state of 620, and the water treatment was continued. It was a difficult situation. When the state in the aeration tank was observed, a large amount of filamentous bacteria was observed in the activated sludge of Comparative Example 2, and this abnormal occurrence of filamentous bacteria is considered to be the cause of the deterioration of sedimentation.
Furthermore, the activated sludge in each settling tank after the treatment used in the treatment of Example 3 and Comparative Example 2 was dehydrated with a filter cloth compression type dehydration test apparatus, and the moisture content of the dehydrated cake was measured. As a result, it was 82% in Example 3 and 86% in Comparative Example 2, and the effect of improving the dewaterability of sludge could be confirmed.

<Example 4>
In Example 1, biological treatment was performed in the same manner as in Example 1 except that sewage sludge incineration ash was not added to the raw water, but sewage sludge incineration ash was added to the aeration tank. The amount of sewage sludge incineration ash added was such that the amount of incineration ash in the aeration tank was 10 mg / l with respect to the amount of treated wastewater. As a result, it was confirmed that good treatment was performed as in Example 1.

<Example 5>
In Example 1, the biological treatment was performed in the same manner as in Example 1 except that the sewage sludge incinerated ash was not added to the raw water, but the sewage sludge incinerated ash was added to the returned sludge into the aeration tank. The amount of sewage sludge incinerated ash added was such that the amount of incinerated ash in the aeration tank to which the returned sludge was returned was 10 mg / l with respect to the amount of treated wastewater. As a result, it was confirmed that good treatment was performed as in Example 1.

  As an application example of the present invention, it can be applied to various organic wastewaters having various properties, realize more economical and better treatment of organic wastewater, and effectively use incineration ash of organic waste Can be achieved at the same time.

Claims (5)

  Organic wastewater treatment method that uses biologically treated organic wastewater using incinerated ash obtained by incineration of organic waste, and uses raw water that is the organic wastewater added with the above incineration ash Or adding the incineration ash to the biological reaction tank, or adding the incineration ash to the return sludge, or at least one of the incineration ash addition steps, .   The method for treating organic waste water according to claim 1, wherein the incinerated ash contains at least 5 g of phosphorus in terms of oxide in 100 g of the incinerated ash.   Incineration ash is selected from the group consisting of sewage sludge, surplus sludge generated from biological treatment of industrial wastewater, dredging, food residues, agricultural waste, livestock / poultry manure, livestock waste, aquatic waste and forest waste The method for treating organic wastewater according to claim 1 or 2, wherein the organic wastewater is obtained by incineration of organic waste containing at least one of them.   Organic wastewater, pulp and paper factory wastewater, wastepaper recycling factory wastewater, petrochemical industry wastewater, organic synthetic chemical factory wastewater, fat and oil chemical wastewater, pharmaceutical / pharmaceutical intermediate wastewater, textile industry wastewater, dyeing wastewater, scouring wastewater, metal The processing method of the organic waste_water | drain of any one of Claims 1-3 selected from the group which consists of surface treatment and a degreasing waste water, food manufacturing waste water, paper manufacture waste water, and chemical factory waste water.   It is a chemical | medical agent used for the processing method of the organic waste_water | drain of any one of Claims 1-4, Comprising: Incineration ash obtained by incinerating organic waste becomes a main component, It is characterized by the above-mentioned. Wastewater treatment chemical.