JP2008012476A - Wastewater treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wastewater treatment system having high sludge volume reducing effect. <P>SOLUTION: In this treatment system, a sludge volume reducing agent 13 is added to an aeration tank 3, a biological agent 14 is added to at least one of an activated sludge settling tank 4, a chemical settling pond 8, or a thickening tank 11, and an enzyme 15 decomposing organic matter into water and carbon dioxide is added to the thickening tank 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wastewater treatment system excellent in volume reduction of excess sludge.

  Conventionally, wastewater from factories, toilets, kitchens, and the like is decomposed using microorganisms to ultimately reduce the amount of remaining sludge. Microorganisms are classified into aerobic microorganisms that proliferate in the presence of oxygen and anaerobic microorganisms that dislike the presence of oxygen, and many proposals have been made for treatment using either one or these in succession.

  In Patent Document 1, when the excess sludge is subjected to anaerobic treatment and volume reduction by aerobic treatment, the pH is set to 9 to 13 (alkali treatment) before the aerobic treatment, and the aerobic / anaerobic treatment temperature. It is disclosed that promoting the volume reduction of sludge by keeping the temperature between 40 and 80 ° C.

  In Patent Document 2, ammonia nitrogen (NH4-N) in raw water is converted to nitrate nitrogen (NOx-N) by nitrifying bacteria, and this nitrate nitrogen (NOx-N) is removed by anaerobic microorganisms. The contents of nitrogen and discharge as nitrogen gas (N2) are disclosed.

  Patent Document 3 discloses that the sludge is solubilized by subjecting the sludge to pressurization before treatment with microorganisms and then depressurization so that the sludge can be efficiently decomposed by microorganisms.

  Patent Document 4 discloses that a solubilizer is added to surplus sludge, an ultrasonic wave is applied, and a microbial treatment is performed after a vacuum expansion treatment is performed. In particular, as a solubilizer, NaOH, KOH, Mg Examples include alkalis such as (OH) 2 and Ca (OH) 2, and bacteriolytic agents such as hydrogen peroxide, sodium hypochlorite, and ozone that exert an action of destroying microbial cells.

  In Patent Document 5, as a means for reducing excess sludge, a microorganism culture tank is attached to the sludge concentration tank, and a microorganism mixing apparatus in which a mixture of a corrosive substance and a microorganism is added to the microorganism culture tank. It is disclosed.

  In Patent Document 6, a methane luminescence tank is disposed upstream of a denitrification tank, a nitrification tank is disposed downstream of the denitrification tank, and a deoxygenation tank is disposed downstream of the nitrification tank. It is disclosed that biogas is supplied to a deoxygenation tank and the biogas and dissolved oxygen are reacted to render both harmless.

  In Patent Document 7, waste water is fed into the bottom of an aerobic contact digestion unit and allowed to flow as an upward flow to perform aeration and aerobic microbial treatment. The apparatus of the structure which introduce | transduces into the aerobic contact digestion part and introduce | transduces the sludge isolate | separated here here again is disclosed.

  Patent Document 8 provides a recovery step for extracting organic components contained in the reduced sludge in the form of methane gas after the sludge volume reduction processing step, and the recovered methane gas is used in the sludge volume reduction processing step. Reuse is disclosed.

JP 2000-185299 A JP-A-63-72398 JP 2003-305499 A JP-A-2005-230582 JP 2003-225694 A JP 2003-24980 A JP-A-1-168395 JP 2002-35779 A

  In the above wastewater treatment, the sludge that remains finally is reused as a raw material for cement. However, if the sludge remains excessively, it cannot be disposed of. Therefore, it is desired that there is as little surplus sludge as possible, but the above-described conventional technology is not sufficient.

In order to solve the above-described problems, a wastewater treatment system according to the present invention is a wastewater treatment system including an aeration tank, an activated sludge precipitation tank, a nitrification tank, a denitrification tank, a precipitation tank, and a concentration tank. At least two of 3) were implemented.
(1) Add sludge reduction solvent to aeration tank drainage.
(2) A biopharmaceutical is used in at least one of an activated sludge settling tank, a settling tank, and a concentration tank.
(3) An enzyme that accelerates the reaction of decomposing organic substances into water and carbon dioxide is added to the concentration tank.

  There is an optimum temperature range for the enzyme, and in the concentration tank, the water temperature is maintained at 25 ° C. to 35 ° C. to activate the enzyme.

As the sludge reducing solvent, alkali such as NaOH, KOH, Mg (OH) 2, Ca (OH) 2, or / and a bacteriolytic agent such as hydrogen peroxide, sodium hypochlorite and ozone are suitable. An example is Kuridus S100 (trade name) manufactured by Kogyo Co., Ltd.
In addition, the biopharmaceutical is preferably a product obtained by breeding microorganisms collected from water or soil on a porous material such as barley-stone, for example, Envirozain (trade name) manufactured by Kikusui Protech Co., Ltd. .
As the enzyme, an enzyme that promotes a reaction for decomposing an organic substance into water and carbon dioxide gas is selected. For example, Aqua Lift 700P (trade name) manufactured by Aqua Service Co., Ltd. may be mentioned.

  According to the present invention, by treating the waste water using at least two of the sludge volume reducing agent, the enzyme and the bio preparation, than the case where the sludge volume reducing agent, the enzyme and the bio preparation are used alone, respectively. The volume of sludge can be reduced by the synergistic effect when the additive is used.

  Specifically, as shown in the following (table), BOD, SS, oil content, and TP (phosphorus) were greatly reduced, and the amount of sludge generated was 160 tons per year, but was reduced to 48 tons. In the table, “raw water” is treated with sludge volume reducing agent, enzyme and bio preparation, “activated sludge treated water” is treated water with sludge volume reducing agent, and “treated water” uses bio preparation. Represents treated water.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall view of a wastewater treatment system according to the present invention. In the wastewater treatment system, the most upstream part is a pretreatment tank 1 for wastewater, and the raw water preparation tank 2 and the aeration tank are sequentially arranged downstream from the pretreatment tank 1. 3, an activated sludge settling tank 4, a nitrification tank 5, a denitrification tank 6, a nitrogen removal settling tank 7, a coagulation settling tank 8, a sterilization tank 9, and a filter 10 are provided, and the nitrogen removal settling tank 7 and the coagulation settling tank 8 are further provided. And a dehydrator 12 for dehydrating the precipitate from the concentration tank 11.

  In the aeration tank 3, BOD, COD, SS and oil are removed by aeration. In the nitrification tank 5, ammoniacal nitrogen (NH 4 -N) is converted into nitrate nitrogen (NOx-N) by nitrifying bacteria, In the denitrification tank 6, the nitrate nitrogen (NOx-N) is denitrified by anaerobic microorganisms and discharged as nitrogen gas (N2).

  In the present invention, the sludge volume reducing agent 13 is added to the aeration tank 3. As the sludge volume reducing agent, for example, an alkali such as NaOH, KOH, Mg (OH) 2, Ca (OH) 2 or a lysing agent such as hydrogen peroxide, sodium hypochlorite, ozone or the like is used.

  In the present invention, the biopharmaceutical 14 is submerged in at least one of the activated sludge settling tank 4, the coagulation settling tank 8, or the concentration tank 11. The biopharmaceutical 14 is preferably a product obtained by breeding a microorganism collected from water or soil on a porous material such as barley stone. When this biopharmaceutical 14 comes into contact with sludge, microorganisms propagating on the surface of the porous body consume sludge as a nutrient source, and the volume of sludge can be reduced.

  In the present invention, the enzyme 15 is added to the concentration tank 11. As the enzyme 15, an enzyme having a function of promoting a reaction of decomposing an organic substance (hydrocarbon) in the concentration tank 11 into water and carbon dioxide gas is selected.

  FIG. 2 is a graph showing the change over time in the sludge removal rate when only the sludge volume reducing agent is used, FIG. 3 is a graph showing the change over time in the sludge removal rate when using only the enzyme, and FIG. It is a graph which shows a time-dependent change of the sludge removal rate at the time of using. On the other hand, FIG. 5 is a graph showing the change over time in the sludge removal rate when using a sludge volume reducing agent and an enzyme, and FIG. 6 is a graph showing the change over time in the sludge removal rate when using a sludge volume reducing agent and a biopharmaceutical. FIG. 7 is a graph showing the change over time in the sludge removal rate when a biopharmaceutical and an enzyme are used.

  FIG. 2 shows that when only the volume reducing agent is used, the sludge removal rate is around 6%. Moreover, FIG. 3 shows the sludge removal rate when only the enzyme is used, and when the water temperature (water temperature in the concentration tank) is 20 ° C., the enzyme activity is not sufficient, and the water temperature is preferably in the range of 25 ° C. to 35 ° C. I understand. Further, FIG. 4 shows that the sludge removal rate is limited to about 20% when only the biologic is used.

  In addition, from the results of FIGS. 5, 6 and 7, it can be said that the volume reduction effect is higher when two or more kinds of sludge volume reducing agents, biopharmaceuticals and enzymes are used alone.

Overall view of wastewater treatment system according to the present invention A graph showing the change over time in the sludge removal rate when only the sludge volume reducing agent is used. Graph showing time-dependent change of sludge removal rate when using only enzyme A graph showing the change over time in the sludge removal rate when only biologics are used Graph showing the time course of sludge removal rate when using sludge volume reducing agent and enzyme Graph showing the time course of sludge removal rate when using sludge volume reducing agent and biopharmaceutical Graph showing the change over time in the sludge removal rate when using biopharmaceuticals and enzymes

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pretreatment tank, 2 ... Raw water preparation tank, 3 ... Aeration tank, 4 ... Activated sludge precipitation tank, 5 ... Nitrification tank, 6 ... Denitrification tank, 7 ... Nitrogen removal sedimentation tank, 8 ... Coagulation sedimentation tank, 9 ... Sterilization Tanks, 10 ... filters, 11 ... concentration tanks, 12 ... dehydrators, 13 ... sludge volume reducers, 14 ... bio preparations, 15 ... enzymes.

Claims (6)

In a wastewater treatment system equipped with an aeration tank, an activated sludge settling tank, a nitrification tank, a denitrification tank, a settling tank and a concentration tank, a sludge reducing solvent is added to the wastewater of the aeration tank and the activated sludge settling tank, the settling tank and the concentration tank A wastewater treatment system using a biopharmaceutical in at least one of the tanks. In a wastewater treatment system equipped with an aeration tank, an activated sludge settling tank, a nitrification tank, a denitrification tank, a settling tank and a concentration tank, a sludge reducing solvent is added to the drainage of the aeration tank and organic substances are added to the concentration tank with water and carbon dioxide. A wastewater treatment system characterized by adding an enzyme that promotes a decomposition reaction. In a wastewater treatment system including an aeration tank, an activated sludge settling tank, a nitrification tank, a denitrification tank, a settling tank, and a concentration tank, a biopharmaceutical is used in at least one of the activated sludge settling tank, the settling tank, and the concentration tank and the concentration is performed. A wastewater treatment system, wherein an enzyme that promotes a reaction to decompose organic matter into water and carbon dioxide gas is added to the tank. In a wastewater treatment system equipped with an aeration tank, an activated sludge settling tank, a nitrification tank, a denitrification tank, a settling tank and a concentration tank, a sludge reducing solvent is added to the wastewater of the aeration tank, and the activated sludge settling tank, the settling tank and the concentration tank A wastewater treatment system, wherein a biopharmaceutical is used in at least one of the tanks, and an enzyme that promotes a reaction of decomposing organic substances into water and carbon dioxide gas is added to the concentration tank. The wastewater treatment system according to any one of claims 1 to 4, wherein the water temperature in the concentration tank is maintained between 25C and 35C. The wastewater treatment system according to any one of claims 1 to 4, wherein the sludge reducing solvent is an alkali such as NaOH, KOH, Mg (OH) 2, Ca (OH) 2, or / and hydrogen peroxide, It is a lysing agent such as sodium chlorite and ozone, and the biopharmaceutical product is produced by breeding microorganisms collected from water or soil in a porous material such as barley stone, and the enzyme converts organic matter into water and carbon dioxide. A wastewater treatment system characterized by promoting a decomposition reaction.