KR100373413B1 - Process for removing heavy metal components from fly ash by using microorganism - Google Patents

Abstract

The present invention relates to a method for removing heavy metals in an incineration ash by using microorganisms. When the medium is mixed with water and incubated in the incineration ash, the microorganism is added to the culture, and the metal in the incineration ash is formed into an aqueous solution by the organic acid generated as the microorganism grows. When the metal is eluted and adsorbed to the microorganism by the metal adsorption capacity of the microorganism in the aqueous solution, the microorganism is recovered by recovering the microorganism.

According to the method of the present invention, since heavy metals and the like contained in the incineration ash can be adsorbed and recovered by microorganisms, the metal in the incineration ash can be removed in an environmentally friendly manner within a short time without any special device.

Description

Process for removing heavy metal components from fly ash by using microorganism}

The present invention relates to a method for removing heavy metals contained in an incineration ash. More specifically, the present invention relates to a method for removing heavy metals contained in incineration ash generated by coal incineration using microorganisms.

Since incineration ash generated by incineration of coal contains metals such as copper, arsenic, chromium, and zinc, when landfilled directly, the metals eluted from the incineration ash contaminate water quality and cause serious environmental problems. do.

As a countermeasure, until now, the method of embedding an incineration ash after storing it for a long time in a limited space rather than embedding it is used. In the case of long-term incineration (eg, 10 years or more), metals in the incinerators have been reported to be immobilized to the material in the incinerators, so that the metals do not elute at the time of landfilling. Conference Fly Ash Disposal and Utilization: India Central Board of Inigation and Power New Delhi, 1998, pp 1-7].

However, this method takes a long time and requires a large amount of temporary storage space and is not a technology for effectively removing and stabilizing metal.

Recently, a heat treatment method has been developed to vaporize a metal by heating the incinerator at a high temperature (800-1000 ° C.) and recover the evaporated metal again [A. Jakob S. Stuck, "Complete Heavy Metal Removal from Fly Ash by Heat Treatment": Environ. Sci. Technal 1996, 30, 3275-3283. However, this method is economically unreasonable because it not only consumes a lot of energy but also requires a separate device for recovering evaporated metal.

Therefore, the present inventors solve the problems of the prior art, and continue to research for the development of a method for effectively removing the harmful heavy metals from incineration ash, economical and environmental that can remove heavy metals from incineration ash using microorganisms A friendly method was developed to complete the present invention.

Referring to the heavy metal removal method in the incineration ash according to the present invention in detail.

That is, when the microorganisms are properly mixed with water and the medium so that the microorganisms grow, the microorganisms are grown and the organic acid is produced as the microorganisms grow, and the organic acid lowers the pH in the treatment tank.

Accordingly, the metal in the incineration ash is eluted into the aqueous solution phase, so that the solubility increases as the pH is lowered.

At this time, the eluted metal is adsorbed to the microorganism by the metal adsorption capacity of the microorganism present in the aqueous solution.

Therefore, the metal contained in the incineration ash is removed together by recovering the microorganisms on which the metal is adsorbed.

The microorganisms that can be used in the present invention can be used for all kinds of microorganisms that emit organic acids upon growth and have a metal adsorption capacity. Examples of such microorganisms include some molds and yeasts that can grow at low pH.

Particularly preferably used is a microbial fungus called Aspergilus niger. When the microorganism is stirred at low speed, the fungus tangles like a thread and can be easily separated by filtration.

The medium added for the cultivation of the microorganism can be used as long as it is a medium suitable for the growth of the selected microorganism, the culture temperature is arbitrarily selected from a temperature range suitable for the growth of the microorganism, about 30 ℃ is preferred.

<Example>

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to this embodiment.

Example 1

100 g of the incineration ash was pulverized finely with a blender and mixed in 1 L of distilled water. To this was added 10 g of YM medium (3 g / l yeast extract, 3 g / l malt extract, 5 g / l peptone, 10 g / l glucose) and then put into a 2 L incubator and sterilized. The same medium was inoculated with 5% of microorganism-fungus (Aspergilus niger) cultured one day ago.

Air was supplied at a rate of 0.05 vvm without pH adjustment at 30 ° C. Stirring at a relatively low speed of 100 rpm allowed the fungus to entangle like a yarn and easily separate from the culture.

After incubation, the cells were filtered / separated using a 40 mesh sieve, dried at 100 ° C. for 1 day, and then dried. Metal content was measured using Atomic Absorption.

The culture results for 5 days are shown in Table 1.

Day 0 One 2 3 4 5 Cell volume (g / ℓ) 0 0.3 0.7 1.5 2.5 2.7 pH 7 5.2 4.0 3.2 3.2 3.2 Glucose (g / ℓ) 10 7.3 5.6 2.3 1.1 0 Incinerator Residual Cu (ppm) 165 141 105 54 31 13 Cu recovery rate of microorganism (%) 0 14.5 36 67 81 92 Incinerator ash (ppm) 280 230 150 45 29 14 % Of microorganisms in zinc 0 18 46 84 89 94

As shown in the results of the above embodiment, according to the present invention can be recovered by adsorbing metals such as heavy metals contained in the incineration ash to the microorganisms, it is possible to remove the metal in the incineration ash in an environmentally friendly manner in a short time without a special device It can be effective. In addition, since the scale of implementation does not affect the growth of microorganisms, it is applicable to large scale processes.

Claims (2)

When the incineration ash is mixed with water and a medium, and microorganisms are added and cultured, the metal in the incineration ash is eluted into an aqueous solution by the organic acid generated as the microorganism grows, and the metal is adsorbed to the microorganism by the metal adsorption capacity of the microorganism in the aqueous solution. If so, the method for removing heavy metals in the incineration ash using a microorganism, characterized in that by recovering the microorganism. [Claim 2] The method of claim 1, wherein the microorganism is Aspergilus niger.