JPH04310292A - Treatment of methanol-containing waste water - Google Patents

Abstract

PURPOSE:To perform high load methane fermentation treatment by allowing methane bacteria belonging to the genus methganosarcina or Methanococcus live in seed sludge. CONSTITUTION:In a method for high temp. methane fermentation treatment of methanol-containing waste water by an ascending flow type anaerobic sludge bed method, granular sludge of medium temp. fermentation treatment is used alone or together with anaerobic digested sludge as seed to sludge to start high temp. methane fermentation treatment.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is an upflow anaerobic sludge bed method (Upflow Anaerobic Sludge Bed Process) for organic wastewater containing methanol discharged from food, chemical, pulp and paper industries, etc.
robic Sludge BlanketProce
ss, hereinafter referred to as the UASB method. ).

0002

[Prior art] Organic wastewater containing methanol is
Found in the chemical, paper and pulp industries, etc. In particular, kraft pulp drain wastewater discharged at high temperatures in the pulp and paper industry contains a large amount of methanol, making it highly applicable to high-temperature methane fermentation treatment. Methanol at high temperature (50-55℃)
The methane bacteria that can be assimilated are limited to the genus Methanosarcina and Methanococcus. Since these bacteria have a spherical shape, they are difficult to turn into granules when starting up with anaerobic digestion sludge as seed sludge in the UASB method, and fixed bed methane fermentation treatment is usually applied. (Paper and Pulp Technology Times, August 1988, P66-P70
)

0003

[Problems to be Solved by the Invention] In order to solve the above-mentioned problems in the prior art, the present invention uses granular sludge obtained from a UASB reactor for medium-temperature methane fermentation as a seed sludge, and uses Methanosarcina sp. The purpose of the present invention is to provide a method for treating methanol-containing wastewater that allows methane bacteria of the genus Coccus to live and enables high-load methane fermentation treatment.

0004

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for treating methanol-containing wastewater with high-temperature methane fermentation using an upflow anaerobic sludge bed method. This is a method for treating methanol-containing wastewater characterized by starting up sludge as seed sludge, and the present invention also provides a method for treating methanol-containing wastewater by high-temperature methane fermentation using an upflow anaerobic sludge bed method. , a method for treating methanol-containing wastewater is characterized by starting up granule sludge from mesophilic methane fermentation treatment and anaerobic digestion sludge as seed sludge.

[0005] The UASB method allows raw water to flow upward from the bottom of the fermenter, without using a carrier for bacteria to adhere to.
It is an anaerobic microbial treatment technology that forms a sludge bed by flocculating or granulating sludge (bacteria) and can tolerate a higher volume load to ensure a high concentration of microorganisms in the fermenter. , medium-temperature granule sludge is used as seed sludge in a compacted state from the bottom of the reactor.
The tank is filled to a depth of 1.5 m, and raw wastewater is passed through in an upward flow. Inside the mesophilic granule sludge, there are many filamentous methane bacteria of the genus Methanothrix that assimilate acetic acid. Since the wastewater contains no acetic acid and only methanol, the methane bacteria belonging to the genus Methanothrix gradually become inactive, and in their place, methane bacteria belonging to the genus Methanosarcina or Methanococcus begin to inhabit the granules. Usually, granule sludge contains 20 to 40% Ca, depending on the wastewater composition.
Because it contains inorganic compounds such as Fe, and these serve as a support for methane bacteria, it is an environment in which even spherical methane bacteria of the genus Methanosarcina or Methanococcus can easily inhabit. By taking advantage of this unique structure of granule sludge, it has become possible to immobilize methane bacteria of different shapes. Furthermore, by mixing medium-temperature granule sludge and high-temperature digested sludge and starting up as seed sludge, the former will support high-temperature methane bacteria, and the latter will serve as a seed for high-temperature methane bacteria. The mixing ratio of both may be about 1:4 to 2:1, preferably about 1:2 to 1:1 in MLVSS weight ratio.

[0006]

[Effect] In the fixed bed method that is commonly used for high-temperature methane fermentation treatment of methanol-containing wastewater, methane bacteria of the genus Methanosarcina or Methanococcus are attached to the packing material, so the adhesion state may vary depending on the properties of the surface of the filter material. It is difficult to understand the amount of bacteria in the reactor. In the present invention, since bacteria can be immobilized inside and on the surface of the granule sludge, operation similar to the normal medium temperature UASB method is possible, making it easy to grasp and handle the amount of bacteria in the reactor.

[0007]

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. Example 1 Using a UASB reactor with a tank effective capacity of 33 liters and using medium-temperature granule sludge as the seed sludge for wastewater containing a large amount of methanol discharged from a food factory at a temperature of 50 to 55 °C (Run 1) ) and when high temperature sewage digested sludge was used as seed sludge (Run 2), a comparative experiment was conducted. The raw water properties are shown below. Most of the organic matter is methanol. Raw water properties... pH: 7.7 Methanol: 8300mg/l TOC: 3800 BOD: 8600 CODcr: 14000 SS
: 10〃

FIG. 1 shows an overview of the processing results. In Run 1 (in which medium-temperature granule sludge was used as the seed sludge), the CODcr load was increased stepwise to 15 Kg/m3·d on the 40th day and 40 Kg/m3·d on the 70th day. Treated water CODcr
is stable at around 100 mg/l. Although the MLVSS concentration in the sludge bed decreased slightly at the beginning, COD
cr gradually increased with increasing load and reached 8% at day 130. When the granule sludge in the tank was collected and observed under a scanning electron microscope, it was confirmed that many methane bacteria of the genus Methanosarcina were living on the surface and inside of the granules.

On the other hand, in Run 2 (when high-temperature sewage digested sludge is used as seed sludge), the CODcr load is 15 kg/m
Things are going well up to 3.d, but beyond that (70
Day 2) The treated water CODcr increased and the treatment results deteriorated. Furthermore, the MLVSS concentration in the sludge bed was initially 2%, but it increased to 3 to 4%, but did not rise above that. When the reactor sludge was collected and observed under a scanning electron microscope, it was found that the methane bacteria of the genus Methanosarcina were clustered in a lump shape with a particle size of about 0.1 to 0.3 mm. In this case, when digested sludge is used as seed sludge, there is no carrier to immobilize the spherical methane bacteria of the genus Methanosarcina, so it is thought that when the load becomes high, the bacteria will be washed away. It will be done.

Example 2 Using the same UASB reactor as Example 1,
Regarding kraft pulp drain wastewater* (methanol accounts for 70 to 80% of the total organic matter) discharged from a pulp and paper mill at a temperature of An example of an experiment conducted as 1) is shown below. The raw water properties are as follows. pH: 9.0 Methanol: 4500mg/l TOC: 3360 BOD: 6000 CODcr: 9520 *After steam stripping (most of the sulfur content has been removed)
Table 1 shows elapsed days and CODcr, volumetric load, CODcr
The relationship between the removal rate and the methane production activity of the granule sludge in the sludge bed is shown.

[0011] As is clear from Table 1, the start-up is slightly slower than when the entire amount of medium-temperature granule sludge in Example 1 is inoculated, but the CODc
A stable treatment result with a CODcr removal rate of 80% was obtained at a volumetric load of 20 Kg/m3/d.

[Table 1]

0012

[Effects of the Invention] As is clear from the above results, in the present invention, by using medium-temperature granule sludge as seed sludge, high-temperature UASB treatment of methanol-containing organic wastewater is made possible.

[Brief explanation of drawings]

FIG. 1 is a graph showing the processing results of Example 1.

Claims (2)

[Claims] Claim 1: A method for treating methanol-containing wastewater by high-temperature methane fermentation using an upflow anaerobic sludge bed method, characterized in that granule sludge from medium-temperature methane fermentation treatment is started up as seed sludge. Processing method. 2. A method for treating methanol-containing wastewater by high-temperature methane fermentation using an upflow anaerobic sludge bed method, characterized in that granule sludge from medium-temperature methane fermentation treatment and anaerobic digestion sludge are used as seed sludge for startup. A method for treating methanol-containing wastewater.