JPH0662875A - Production of bio-polyester - Google Patents

Abstract

PURPOSE:To make it possible to utilize discharge water in a feed source of carbon by putting a part of activated sludge taken out from an aerobic tank in a bio-polyester producing tank and then giving a carbon source to activated sludge in the bio-polyester producing tank kept in an unaerated state. CONSTITUTION:Activated sludge from an aerobic tank 15 and discharge water during treatment are charged into a precipitation tank 17 and the activated sludge 33 is precipitated in the precipitation tank 17 and the activated sludge is separated from the treated discharge water. Organic substances are removed from the treated water 22 and the treated water is discharged and simultaneously part of activated sludge 33 is returned to the first step as a return sludge. The activated sludge 32 in the aerobic tank 15 is taken out and discharge water or a carbon source for producing polyester is fed to the activated sludge 32 to produce the objective bio-polyester such as PHB in the activated sludge. At this case, even if a nitrogen source exists in the discharge water or the carbon source for producing the polyester, it offers no problem. In the bio- polyester producing tank 19, aeration is not carried out and the tank 19 is not a closed type and is kept in a improper stirring state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing biopolyester using activated sludge.

[0002]

2. Description of the Related Art The following methods are known as prior art. <A> Method using polyester-producing bacteria (Japanese Patent Laid-Open No. 57-
No. 150393) For example, by using known producing bacteria such as Alcaligenes eutrophus, Pseudomonas oleovolans, and Bacillus megaterium, any one (or a plurality) of nutrient salts necessary for growth in the culture medium, such as nitrogen, phosphorus, and inorganic salts. It is necessary to supply abundant carbon sources such as organic acids by depleting these polyester-producing bacteria in a non-growing state. Usually, it is starved of nitrogen. <B> Method Using Activated Sludge The present applicant has invented a method for culturing a wide variety of microbial populations such as activated sludge to produce PHB (poly-β-hydroxybutyric acid) (Japanese Patent Laid-Open No. Hei 10 (1999) -242242). No. 3-143397). Microorganisms generally lack biosynthesis when some of the nutrients required for reproduction are deficient, and tend to start accumulating energy storage substances in the body using carbon sources. Therefore, in the above method, nitrogen is artificially made into a deficient nutrient,
It gives a carbon source in an aerobic state and produces PHB in microorganisms.

[0003]

However, the conventional method has the following problems. <B> In a system that produces PHB from a carbon source in wastewater as a raw material while performing wastewater treatment using activated sludge, PHB is not produced in the presence of a nitrogen source, so the nitrogen content in the wastewater is removed. There was a need. <B> Since PHB is generated in an aerobic state, aeration is required, and power for that is required, resulting in high energy cost.

[0004]

An object of the present invention is to provide a method for producing biopolyester using activated sludge even in the presence of a nitrogen source.

[0005]

The present invention uses poly-β-hydroxybutyric acid (PHB) or its copolymer or PHA (poly-β-hydroxyalkano) by using activated sludge used in an organic wastewater treatment method. Ate) (hereinafter referred to as biopolyester such as PHB) in the activated sludge cells. The present invention uses an activated sludge under an aerobic condition of an activated sludge that alternately circulates anaerobic conditions and aerobic conditions, and uses this activated carbon in a non-aeration state as a carbon source (acetic acid, propionic acid, butyric acid or other lower fatty acid or carbon). This is a method for producing a biopolyester such as PHB in the presence of a nitrogen component (such as ammoniacal nitrogen) in the presence of two or more organic acids). In this method, biopolyesters such as PHB can be produced even in the presence of a nitrogen source, which has not been produced in the past with a nitrogen source.

Embodiments of the present invention will be described below with reference to the drawings. <A> Wastewater treatment device 1 Wastewater (organic matter-containing liquid) 21 is activated sludge 3 as shown in FIG.
The treated water 22 is treated by the wastewater treatment device 1 including the anaerobic tank 13, which has 1, 32, and 33, the aerobic tank 15, and the precipitation tank 17.
Is discharged as. The activated sludge used at the beginning was taken from an urban end-of-life treatment plant. This contains a wide variety of fungi. The drainage 21 used the thing containing the component of Table 1.

[0007]

[Table 1] Anaerobic tank 13 is 11.7 liters, aerobic tank 15 is 18.7 liters.
There is a liter, the concentration of activated sludge in both tanks is about 6,500 mg
/ Liter, the amount of waste water supplied is 2 liters / hr, and the amount of returned sludge is 10 liters / hr. The wastewater 21 may be sewage, night urine, organic wastewater, or not generally called wastewater, but may be a culture solution that serves as a substrate for activated sludge containing an organic acid or the like. The drainage 21 is sucked up by the pump 12 from the drainage reservoir 11. Then, the sucked waste water is mixed with the activated sludge 33 returned from the settling tank 17 by the pump 18, and enters the anaerobic tank 13.

<B> Anaerobic tank 13 The anaerobic tank 13 is of a closed type, and the activated sludge 31 in the tank consumes the dissolved oxygen in the liquid in the tank to be in an anaerobic state. The activated sludge 31 is stirred by the motor 14 together with the drainage, and moves in the anaerobic tank 13. The activated sludge discharged from the anaerobic tank 13 and the wastewater being treated then enter the aerobic tank 15.

<C> Aerobic tank 15 The activated sludge 32 in the aerobic tank 15 and the wastewater being treated are aerated by the air 16 taken in by a blower or the like to receive aeration. The activated sludge discharged from the aerobic tank 13 and the wastewater being treated then enter the settling tank 17.

<D> Settling tank 17 The activated sludge 33 in the settling tank 17 is settled, and the activated sludge and the treated wastewater are separated. Organic matters are removed from the treated water 22 and the treated water 22 is discharged. On the other hand, a part of the activated sludge 33 returns first as return sludge.

<E> Biopolyester production tank 19 The activated sludge 32 in the aerobic tank 15 is taken out, and drainage or a carbon source for polyester production is supplied to this to produce biopolyester such as PHB in the activated sludge. Let In this case, there is no problem even if there is a nitrogen source in the waste water or the carbon source for polyester production. The biopolyester production tank 19 does not perform aeration, and is not a closed type like an anaerobic tank, and may be maintained in a proper stirring state in the tank. Such a state is called non-abnormal.

The first example of bio-polyester production is shown below. <A> First example of biopolyester production In FIG. 2, as the biopolyester production tank 19,
An example of using an Erlenmeyer flask and sealing with a silicon stopper is shown. The production conditions are those shown in Table 2, and the cells are cultured for 144 hours in a thermostatic chamber at 25 ° C. The pH is adjusted to 7.0 with a phosphate buffer. Using butyric acid as a carbon source, total organic carbon (T
OC) concentration was 3,000 mg / liter and no nitrogen component (ammonium sulfate was used) was given (carbon C / nitrogen N ratio = ∞ case) and given case (C / N = 20 and C / For N = 10), shaking culture is performed with and without aeration to produce biopolyester such as PHB. PHB
In the method for extracting biopolyester, etc., after 144 hours, the whole amount of the culture solution is taken out, the cells are collected by a centrifuge, and the sludge is dried. The dried sludge is subjected to extraction treatment with chloroform at 90 ° C., hexane is added to the extract to precipitate biopolyester such as PHB, and after overdrying, the weight is measured.

[0013]

[Table 2] 144 from the start of cultivation of activated sludge collected from this aerobic tank
Table 3 shows the amount of PHB produced in the sludge after the elapse of time.

[0014]

[Table 3] As can be seen from Table 3, in the aeration condition (Experiment 2), when the nitrogen source is present (C / N = 20, 10 cases), PHB
The production of iso-biopolyester is negligible (0.2-0.5% per dry sludge weight). On the other hand, in the case of non-aeration, the production amount is almost the same as the case without nitrogen (C / N = ∞) even if there is a nitrogen source (8.7 to 11.5% per dry sludge weight). (Experiment 1)).

<B> Time-dependent change in biopolyester production A graph showing the time-dependent change in production and accumulation of biopolyester such as PHB, which was carried out under almost the same production conditions as in Experiment 3,
Shown in FIGS. From each graph, regardless of the presence or absence of nitrogen, in each case, the biopolyester accumulation such as PHB once became maximum after the start of the culture, and then showed a decreasing tendency. In each graph, the accumulation rate of biopolyester such as PHB after 144 hours shows almost the same value as in Experiment 3 of Table 2. From the above results, it is understood that activated sludge consumes TOC and accumulates biopolyester such as PHB under non-aeration conditions regardless of the presence or absence of nitrogen. The accumulated amount is 23 ~ per dry sludge weight in 24 ~ 48 hours after culturing.
28% (see the scale on the right side of FIGS. 3-5). In addition,
In the figures, PHB means biopolyester such as PHB.

A second biopolyester production example is shown below. <A> Second biopolyester production example Since the activated sludge 31 in the anaerobic tank 13 of FIG. 1 produces biopolyester in the body, the anaerobic tank 13 also serves as a biopolyester production tank. Therefore, even if the anaerobic tank 13 in FIG. 1 is not so strong in the degree of anaerobicity, if there is no problem in the treated water quality, for example, the DO concentration in the anaerobic tank is 0 to 1 mg / liter, and the redox potential (ORP) is -1
In the case where the final treated water quality achieves the effluent standard even with an anaerobic degree of about 00 to +100 mV, the anaerobic tank is also used as it is as a biopolyester production tank as a modification of the flow of the apparatus of FIG. Such devices are possible. In this case, the activated sludge 31 can be taken out from the anaerobic tank 13 and freeze-dried in the same manner as in the first production example to produce biopolyester from the dried sludge.

[0017]

As described above, the present invention can obtain the following special effects. <B> When supplying the carbon source to the biopolyester production tank, biopolyester can be produced even if nitrogen content is present. Therefore, for example, when the system of the present invention is applied to organic wastewater treatment, the nitrogen content in the wastewater is reduced. Without removing
Wastewater can be used as it is as a carbon source. <B> Since aeration is unnecessary in the biopolyester production tank, aeration power is not required and an energy-saving system can be obtained. <C> By using the anaerobic tank also as the biopolyester production tank, the biopolyester can be produced directly from the activated sludge taken out from the anaerobic tank.

[Brief description of drawings]

[Fig. 1] Overall view of wastewater treatment equipment

Figure 2: Diagram of biopolyester production tank

[Fig. 3] Time-dependent change diagram of accumulated amount of biopolyester in the absence of nitrogen

FIG. 4 is a time-dependent change diagram of the accumulated amount of biopolyester in the presence of nitrogen.

FIG. 5: Time-dependent change diagram of accumulated amount of biopolyester when nitrogen is further present

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Tomozawa 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Taisei Corporation (72) Inventor Katsuo Sato 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Within Taisei Construction Co., Ltd.

Claims (2)

[Claims] 1. An activated air sludge and an organic matter-containing liquid are sequentially fed to an anaerobic tank,
In the wastewater treatment equipment in which the activated sludge is transferred to the aerobic tank and the sedimentation tank, the activated sludge is taken out of the sedimentation tank and returned to the anaerobic tank, and the organic matter-containing liquid is discharged from the sedimentation tank, a part of the aerobic tank is discharged. Taking out the activated sludge and putting it in a biopolyester production tank, supplying a carbon source to the activated sludge in the non-aerated biopolyester production tank, and extracting the biopolyester from the activated sludge obtained in the biopolyester production tank, A method for producing a biopolyester, characterized by: 2. An activated air sludge and an organic matter-containing liquid are successively supplied in an anaerobic tank,
In the wastewater treatment equipment in which the activated sludge is transferred to the aerobic tank and the sedimentation tank, the activated sludge is taken out of the sedimentation tank and returned to the anaerobic tank, and the organic matter-containing liquid is discharged from the sedimentation tank, the activated sludge is partially activated from the anaerobic tank. A method for producing biopolyester, characterized in that sludge is taken out and biopolyester is extracted from the activated sludge taken out from the anaerobic tank.