JPS6324438B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for treating human waste or domestic wastewater in a septic tank type septic tank using immobilized microorganisms.

[Prior art]

Conventional septic tank-type septic tanks have poor treatment performance compared to aeration-type septic tanks, and the purification function deteriorates especially when the temperature rises in summer and when the temperature drops in winter, causing many problems such as deterioration of effluent water quality. have.

[Purpose of the invention]

An object of the present invention is to solve the problems of the prior art and provide an efficient method for purifying human waste or domestic wastewater.

[Structure of the invention]

The present invention includes methane bacteria immobilized by a gel entrapment method and/or methane bacteria immobilized by a gel entrapment method using an organic polymer substance that does not contain a water-soluble silicate compound as a fixed gelling material. This is a method for purifying human waste and/or domestic wastewater, which is characterized by causing anaerobic sludge to exist in a septic tank type septic tank for human waste and/or domestic wastewater.

The present inventors have conducted various studies to solve the above-mentioned problems in septic tank-type septic tanks, and as a result, have completed the present invention.

Several reports have been made to date that the function of a septic tank-type human waste septic tank can be improved by introducing methane bacteria and anaerobic sludge containing methane bacteria into the septic tank. In these conventional methods, a culture solution of methane bacteria itself or a material adsorbed and immobilized on a carrier is introduced.

The present inventors immobilized methane bacteria or anaerobic sludge containing methane bacteria by a comprehensive immobilization method using an organic polymer substance that does not contain water-soluble silicic acid compounds as a gelling agent, and It was discovered that it exhibited excellent functionality when put into a tank-type septic tank.

Next, the present invention will be explained in detail.

In order to demonstrate the effects of the present invention, methane bacteria adsorbed and immobilized on a carrier (activated carbon) using the conventional method, and methane bacteria in which the same amount of methane bacteria was entrapped and immobilized in a gel with a photocrosslinkable resin were tested for household use. A septic tank type human waste septic tank was injected with these immobilized bacteria, and a septic tank type human waste septic tank without these immobilized bacteria was used as a control to investigate the purification ability over the year.

In this investigation, culture solution 50 obtained by culturing methane bacteria for 30 days at 25°C using acetic acid medium was immobilized by adsorbing it on 4 kg of activated carbon, and the same culture solution 50 was immobilized using 8% photocrosslinkable resin. The entrapping and immobilized methane bacteria obtained by entrapping gelatinization were introduced into a household septic tank-type human waste septic tank with an effective volume of 6.4 m ³ . In this case, the photocrosslinkable resin gel was prepared by adjusting the particle size to 1 to 2 mm, and after gelling, it was placed in a KCl solution to harden the surface.

The results are shown in FIG.

As can be seen from Fig. 1, in human waste septic tank a in which immobilized bacteria were not introduced, the BOD removal rate decreased in summer and winter, and the purification function decreased; In human waste septic tank b into which bacteria were introduced, no decrease in purification function was observed in winter, but in summer a decrease in purification function similar to that in tank a was observed. The main reason for this is thought to be that the ammonia concentration in the liquid in the septic tank exceeds 160mg/d in summer, as shown in Figure 1. Such an increase in ammonia concentration in the summer is brought about by the rise in liquid temperature, and is caused by the increase in the liquid temperature, and is caused by the increase in the temperature of the liquid. It was also observed in septic tanks. However, in septic tank c into which gel-entrapping and immobilized methane bacteria was introduced, a high BOD removal rate was achieved throughout the year, and sufficient purification ability was maintained even when the free ammonia concentration exceeded 180 mg/in the summer. .

When the particle size of K-carrageenan gel is 2 mm or more, it will not flow only by liquid flow, so it is effective to put a stirring device in the septic tank to force the fluid to flow. However, since excessive flow causes loss of the gel, it is necessary to appropriately select the stirring intensity in relation to the sedimentation rate of the gel.

It is well known that the reduction in the purifying ability of a septic tank-type human waste septic tank is caused by the reduction in the methane fermentation ability of methane bacteria. That is, methane bacteria ultimately converts organic acids such as acetic acid produced by hydrolysis bacteria and acid fermentation bacteria into methane gas and removes it from the liquid. When this methane bacteria loses its activity, fermentation stops after producing organic acids, and BOD removal is no longer possible. It has often been pointed out that methane bacteria are inhibited by temperature drops and free ammonia and lose their activity. In winter, the deterioration in the purification function of human waste septic tanks into which methane bacteria immobilized by gel entrapment immobilization or carrier adsorption immobilization has been introduced can be improved by using immobilized bacteria to maintain a sufficient amount of methane even at low water temperatures. This is thought to be caused by bacteria being retained in the tank. On the other hand, in the summer, it is thought that most of the methane bacteria that were simply adsorbed and immobilized on the carrier were inactivated by being directly exposed to the toxic effect of free ammonia. This is because the immobilized methane bacteria is stabilized against this toxicity even under high ammonia concentration conditions such as human waste, that is, when free ammonia is produced in summer, or is protected by the gel and is not deactivated. Conceivable.

In addition to the above-mentioned photocrosslinkable resins, other immobilizing gel materials that can comprehensively immobilize anaerobic biological sludge containing methane bacteria and exhibit sufficient biological metabolic functions in septic tanks include k-carrageenan and sodium alginate. , gelatin, agar, polyacrylamide,
Different monomer gelling agents such as copolymers of acrylamide and acrylic acid, organic polymer gelling agents such as polyvinyl acetate, polyvinyl alcohol, photocurable resin prepolymers, hydraulic resin prepolymers, and ethyl cellulose are used.

Although JP-A-60-202794 describes the use of a water-soluble silicic acid compound as a gelling agent or the combined use of a water-soluble silicic acid compound and a synthetic polymer, it is not possible to use an organic silicon compound as a gelling agent. In this case, alcohol is produced during gelation, and the activity of the methane bacteria is significantly inactivated by the alcohol. Moreover, even if alcohol is removed before and after gelation, it is difficult to remove the methane bacteria so that they do not come into contact with oxygen, and thus cannot be used.

Cultivating methane bacteria at a high concentration prior to gel entrapment is to compensate for the deactivation of some of the methane bacteria during the gel immobilization operation, and also to culture the methane bacteria that has been immobilized in the gel in the septic tank. It is clear from the experimental results shown in Fig. 2 that it is extremely effective in fully demonstrating the methane fermentation function after being added to the water. Figure 2 shows methane bacteria pre-cultured (acclimated culture) while continuously supplying human waste supplemented with 5000 mg of acetic acid, and pre-cultured while continuously supplying acetic acid medium containing 20000 mg of acetic acid as the main carbon source and energy source. The figure shows the amount of methane gas generated when methane bacteria was immobilized in a gel as in the survey related to Figure 1 and put into a human waste septic tank, along with a control group. In this case, it is found that it is more effective to use methane bacteria pre-cultured with acetic acid and human waste.

For pre-culturing, it is more economical to use industrial wastewater from food, fermentation, pulp, etc. because the culture solution can be obtained at low cost. In addition, using sewage sludge for this purpose is effective in obtaining highly concentrated methane bacteria, while using human waste fixes human waste-adapted methane bacteria when applying the present invention to a human waste septic tank as described above. It is extremely effective because it can be converted into Furthermore, in order to accumulate more methane bacteria, it is effective to use industrial products such as methanol, ethanol, and acetic acid as a growth source. Furthermore, for example, when using a human waste septic tank as a control, it is possible to obtain high-concentration methane bacteria that are compatible with raw water by freely combining these materials depending on the target wastewater, such as a combination of human waste and acetic acid. Since multiple effects such as these can be obtained, it is effective to entrap and immobilize pre-cultured anaerobic bacteria including methane bacteria in a gel in order to express the purification function of a septic tank type septic tank (anaerobic digestion tank). It is.

In addition to the above, anaerobic bacteria including methane bacteria after gel entrapment fixation can be transferred to various organic wastewaters (including industrial wastewater, human waste, sewage, etc.) similar to the wastewater to be treated, or industrial products (methanol If the anaerobic bacteria in the gel are once grown using a medium containing (including , ethanol, and acetic acid) and then introduced into a septic tank type septic tank, the purification function can be immediately improved. An example of this experiment is shown in FIG.

Before this human waste septic tank was injected with gel-enclosed and immobilized bacteria, organic acids remained in the treated water and the odor caused by butyric acid, grass acid, etc. was extremely bad. Results of sludge gelling and entrapping immobilized bacterial cells post-cultured with acetic acid + human waste, post-cultured only with acetic acid medium containing acetic acid as the main carbon source and energy source, and cases where it was added without post-culture However, after culturing with acetic acid + human waste, the purification function appears immediately. In addition, when compared with the control plot, it can be seen that the purification function was expressed faster in those post-cultured with acetic acid medium alone than in the control plot. That is, when using a product that has been post-cultured with human waste + acetic acid, its purifying function is quickly expressed, so it is extremely effective in preventing pollution such as bad odors.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the effect of the gel-entrapping and immobilized methane bacteria of the present invention, Figure 2 is a diagram showing the effect of pre-culture of the gel-entrapping and immobilized methane bacteria, and Figure 3 is a diagram showing the effect of post-culture. It is a drawing.

Claims (1)

[Scope of Claims] 1 Methane bacteria and/or anaerobic sludge containing methane bacteria are immobilized by a gel entrapment method using an organic polymer substance that does not contain a water-soluble silicic acid compound as an immobilizing gelling agent. A method for purifying human waste and/or domestic wastewater, comprising allowing the immobilized bacterial cells to exist in a septic tank type septic tank for human waste and/or domestic wastewater. 2. Before anaerobic bacteria containing methane bacteria are immobilized by gel, various organic wastewaters, human waste, sewage sludge, methanol medium, ethanol medium and/or acetic acid medium containing ammonia nitrogen and/or urea are used. The method for purifying human waste and/or domestic wastewater according to claim 1, wherein the method is pre-cultured by a method of purifying human waste and/or domestic wastewater. 3 After immobilizing anaerobic sludge containing methane bacteria and/or methane bacteria by gel entrapment method, it is immobilized in various organic wastewaters containing ammonia nitrogen and/or urea, human waste, methanol medium, ethanol medium and/or acetic acid medium. A method for purifying human waste and/or domestic wastewater according to claim 1, wherein the post-cultured product is allowed to exist in a septic tank type septic tank.