JP2008173614A - Wastewater treatment method and treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce heating costs required in an acid generation process in wastewater treatment. <P>SOLUTION: A heat exchanger 15 in installed on a wastewater supply pipeline 16a to an acid generation tank 12. A delivery pipeline 16d for water treated in a methane fermentation tank 13 is connected to an aerobic treatment apparatus through the high temperature side 15 of the heat exchanger. Wastewater supplied to the acid generation tank 12 is preheated by heat energy of the treated water treated in the methane fermentation tank 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wastewater treatment method and a treatment apparatus.

  Wastewater discharged from factories, etc. is first recycled as fuel by decomposing organic matter in the wastewater into methane gas in the anaerobic treatment process using anaerobic microorganisms, and then using the aerobic microorganisms. In the tempering process, inorganic substances such as phosphorus and nitrogen are removed, and chemical substances that adversely affect the environment are removed before being drained. The anaerobic treatment process consists of an acid generation process that decomposes organic matter in wastewater into low molecular weight fatty acids that can be fermented with methane, such as formic acid, acetic acid, propionic acid, etc. It consists of a methane fermentation process that decomposes low-molecular-weight fatty acids produced in the acid production process by methane producers, which are anaerobic microorganisms separate from liquefied bacteria, into methane gas and carbon dioxide. In the aerobic treatment process following the anaerobic treatment process, the aerobic layer is treated with aerobic microorganisms, the sludge layer is separated in the settling tank, and the purification layer present as the supernatant is drained. Such a wastewater treatment method and treatment apparatus are described in Patent Document 1.

The acid generation step and the methane fermentation step are performed independently, because the liquefied bacteria that act on acid generation and the methanogen that acts on methane fermentation can be maintained under optimum conditions, respectively. This is to treat organic wastewater in a short time and to separate and recover gas with high methane purity.
JP 2003-71486 A

  In the acid production step, the reaction by the liquefied bacteria is effectively performed at around 27 to 28 ° C. Therefore, it is necessary to heat the waste water in the acid generation tank to about 27 to 28 ° C. by heating means by steam blowing or the like, which requires heating costs. Particularly in the winter season, the temperature of the wastewater supplied to the acid generation tank is low, so that a larger heating cost is required.

  This invention is made | formed in view of such a situation, and it aims at reducing the heating cost required for the acid production | generation process in wastewater treatment.

  The present invention provides a wastewater treatment method for sequentially performing an acid generation process, a methane fermentation process, and an aerobic treatment process on wastewater, and the wastewater supplied to the acid generation process is discharged from the methane fermentation process. It preheats by carrying out heat exchange with the treated water sent to a tempering treatment process.

  Further, another aspect of the present invention is an acid generator, a methane fermentation tank disposed on the downstream side of the acid generation tank, an aerobic treatment device disposed on the downstream side of the methane fermentation tank, and heat exchange. In the wastewater treatment apparatus comprising a vessel, the heat exchanger exchanges heat between the wastewater supplied to the acid generation tank and the treated water sent from the methane fermentation tank to the aerobic treatment apparatus. The waste water supplied to the acid generation step is preheated by the heat exchange.

  ADVANTAGE OF THE INVENTION According to this invention, the heating cost required at the acid production | generation process in waste water treatment can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The wastewater treatment apparatus in one embodiment according to the present invention is suitable for the treatment of wastewater discharged from, for example, a beer factory, and anaerobic treatment apparatus 10 that treats wastewater anaerobically and treats wastewater aerobically. An aerobic treatment device 20.

  The anaerobic treatment apparatus 10 includes an adjustment tank 11, an acid generation tank 12 that decomposes organic substances contained in the waste water into low molecular fatty acids, a methane fermentation tank 13 that decomposes the low molecular fatty acids and generates methane gas and carbon dioxide gas. A treated water tank 14 for storing treated water after methane fermentation and a heat exchanger 15 are provided. The factory wastewater to be treated is temporarily stored in the adjustment tank 11 in the anaerobic treatment apparatus 10, and from there, the heat exchanger 15, the acid through the wastewater supply pipe 16 a, the wastewater transfer pipe 16 b and the treated water transfer pipe 16 c. The treated water that has been transferred in the order of the production tank 12 and the methane fermentation tank 13 and has undergone anaerobic treatment is stored in the treated water tank 14. Then, the treated water after the anaerobic treatment is transferred from the treated water tank 14 to the aeration tank 21 of the aerobic treatment apparatus 20 through the treated water delivery line 16d.

  The adjustment tank 11 is a tank in which wastewater discharged from the factory is temporarily stored, and the amount of wastewater supplied to the acid generation tank 12 is adjusted according to the degree of anaerobic treatment of the wastewater in the acid generation tank 12 and the methane fermentation tank 13. To do. The temperature of the wastewater stored in the adjustment tank 11 is substantially equal to the outside air temperature, and decreases to, for example, about 15 ° C. in winter. The wastewater stored in the adjustment tank 11 is supplied to the acid generation tank 12 through the drainage supply line 16a.

  The waste water flowing through the waste water supply pipe 16 a is heated by the heat exchanger 15. The heat exchanger 15 exchanges heat between the treated water transferred from the treated water tank 14 to the aeration tank 21 through the treated water delivery pipe line 16d and the wastewater transferred through the drainage supply pipe line 16a, thereby providing a drainage supply pipe line 16a. The waste water supplied to the acid generation tank 12 is preheated. The treated water delivery line 16d that passes through the heat exchanger 15 is integrated with the treated water transfer line 16c, and is a line that transfers treated water from the methane fermentation tank 13 to the aeration tank 21 without passing through the treated water tank 14. It may be.

  In the acid generation tank 12, organic substances in the wastewater are decomposed by anaerobic liquefied bacteria and decomposed into low-molecular fatty acids such as formic acid, acetic acid, propionic acid and the like. The acid production tank 12 needs to be maintained at a temperature of about 27 to 28 ° C., which is the optimum condition for liquefied bacteria. Therefore, the acid generation tank 12 is heated by blowing steam or the like. As a means for heating the acid generation tank 12, an internal heater may be provided in the acid generation tank 12. The wastewater that has been subjected to the acid generation treatment is transferred to the methane fermentation tank 13 through the drainage transfer pipe 16b.

  In the methane fermentation tank 13, the low-molecular-weight fatty acid in the wastewater is further decomposed into methane gas and carbon dioxide gas by anaerobic methanogen. Methane gas and carbon dioxide gas generated in the methane fermentation tank 13 are recovered via the exhaust pipe and can be effectively used as fuel or the like. The temperature of the treated water after being subjected to the methane fermentation treatment in the methane fermentation tank 13 is about 32 ° C. and higher than the drainage temperature in the acid generation tank 12.

  The treated water from which the organic matter has been removed by the methane fermentation tank 14 is transferred to the treated water tank 14 and stored by the treated water transfer pipe 16c. The treated water is temporarily stored in the treated water tank 14 in order to adjust the amount of treated water sent to the aerobic treatment device by the treated water delivery pipe 16d in accordance with the degree of the aerobic treatment which is the next step of the anaerobic treatment. . When there is no need to particularly adjust the amount of treated water sent to the aerobic treatment apparatus, the treated water tank 14 may not be provided.

  The treated water at around 32 ° C. flowing through the treated water delivery line 16d is heated to about 30 ° C. near the outside temperature flowing through the waste water supply line 16a via the heat exchanger 15, and then an aerobic treatment device. It is sent to 20 aeration tanks 21. Therefore, the heating cost of the acid generation tank 12 can be reduced by the amount preheated by the treated water.

  The temperature of the treated water flowing through the treated water delivery line 16d is lowered to, for example, close to 30 ° C. by heat exchange with the wastewater flowing through the drainage supply line 16a. However, since the aerobic treatment apparatus 20 does not require any special temperature management, no trouble occurs even if the temperature of the treated water is lowered by several degrees Celsius.

  The aerobic treatment apparatus 20 includes an aeration tank 21 in which treated water having undergone anaerobic treatment is injected through the treated water delivery line 16d and treated aerobically, and a sedimentation tank 22 that separates the sludge layer. The purification layer existing as the supernatant in the sludge tank 22 is drained as it is, the precipitated sludge layer is circulated to the aeration tank 21, and the surplus is discharged as excess sludge. In the aeration tank 21, inorganic substances such as phosphorus and nitrogen that have not been treated by the anaerobic treatment apparatus 10 are removed from the treated water by the action of aerobic microorganisms.

It is a figure which shows the waste water treatment apparatus of one Embodiment in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Anaerobic processing apparatus 11 Adjustment tank 12 Acid production tank 13 Methane fermentation tank 14 Treated water tank 15 Heat exchanger 16a Drain supply pipe 16b Drain transfer pipe 16c Treated water transfer pipe 16d Treated water delivery pipe 20 Aerobic treatment apparatus 21 Aeration tank 22 Precipitation tank

Claims (2)

A wastewater treatment method that sequentially performs an acid generation process, a methane fermentation process, and an aerobic treatment process on wastewater,
A wastewater treatment method, wherein the wastewater supplied to the acid generation step is preheated by exchanging heat with treated water sent to the aerobic treatment step after the methane fermentation step is completed. An acid generator,
A methane fermentation tank disposed downstream of the acid generation tank;
An aerobic treatment device disposed downstream of the methane fermentation tank;
A wastewater treatment apparatus comprising a heat exchanger,
The heat exchanger is for exchanging heat between wastewater supplied to the acid generation tank and treated water sent from the methane fermentation tank to the aerobic treatment apparatus, and wastewater supplied to the acid generation tank Is preheated by the heat exchange.

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