KR20180061642A - Treatment method of cokes wastewater using algal and bacteria - Google Patents

Abstract

The present invention relates to a method for treating coke wastewater using microalgae and bacteria. More specifically, the present invention relates to a method for treating coke wastewater using microalgae and bacteria, comprising the following steps: culturing microalgae; culturing aerobic bacteria; and removing solid from coke wastewater and inoculating coke wastewater with microalgae and aerobic bacteria. Provided is a method for treating coke waste water, which ensures simple processes while treating coke waste water stably and efficiently.

Description

[0001] The present invention relates to a method for treating coke wastewater using microalgae and bacteria,

The present invention relates to a method for treating coke wastewater using microalgae and bacteria.

The steel production process can be roughly classified into steelmaking, steelmaking, performance, and rolling processes. The ironmaking process is a process for making iron ore and coking coal to produce molten iron (impurities containing a lot of impurities), charging the coking furnace into a coke oven and brewing it at a temperature higher than 1,000 degrees. However, in this process, a gas containing a large amount of toxic substances is generated, which is called a coke oven gas (COG). Since the COG contains toxic substances such as tar, naphthalene, hydrogen sulfide, ammonia and BTEX, it is necessary to further purify the COG gas to recover by-products and distill or collect toxic substances. In this process, Waste water is generated. Phenol, cyanide (CN), cyanide (SCN), and ammonium nitrogen (NH ₄ ⁺ -N) are the most problematic when treating coke wastewater.

The most important process for treating organic matter and nitrogen pollutants in a typical coke wastewater treatment process is the biological nitrification-denitrification process. This process removes most of the organic and inorganic contaminants. However, the toxic substances present in the coke wastewater are mainly due to the activities of ammonium-oxidizing bacteria (hereinafter referred to as 'AOB') and nitrite-oxidizing bacteria (hereinafter referred to as 'NOB') which are mainly involved in nitrification and denitrification It is one of the main causes that makes it difficult to treat nitrogen pollutants especially because it has a very fatal effect. For example, it is known that the activity of AOB and NOB is seriously inhibited even when cyanide is present at only 1-2 mg / L. It is known that cyanide is less toxic than cyanide, but only at a small concentration of 0.5 mg / L It is reported that it corresponds to half the lethal dose of daphnia. In addition to the inhibition of the activity of major communities, the water treatment process consists of anoxic, aerobic, and sedimentation tanks, which are complicated to operate and expensive to maintain and repair.

In order to solve this problem, it is necessary to provide a simple and simple coke waste water treatment method capable of treating nitrogen pollutants of coke wastewater more stably and efficiently.

Patent Registration No. 10-1444643

An object of the present invention is to provide a method for treating coke waste water with a simple process while stably and efficiently treating coke waste water.

In order to achieve the above object,

The present invention relates to a method for culturing microalgae, Culturing aerobic bacteria; And removing the solid matter from the coke wastewater, and inoculating the microalgae and the aerobic bacteria into the coke wastewater. The present invention also provides a method of treating coke wastewater using microalgae and bacteria.

According to the present invention, a microalgae, which is resistant to phenol and a cyanide compound, can be used as Scenedesmus quadricauda) of the ammonium nitrogen by micro algae used as the inorganic nutrient nitrogen in photosynthesis (photoautotrophic), heterotrophic (heterotrophic), or mixed nutrition (mixotrophic) conditions (NH ₄ ⁺ -N), nitrate nitrogen (NO ₃ ^- -N) , And nitrite nitrogen (NO ₂ ^- N) can be treated directly without additional nitrification or denitrification processes.

In addition, using microalgae, which are resistant to phenolic compounds and cyanide compounds, it is possible to treat nitrogen pollutants that have been difficult to treat in the conventional biological nitrification-denitrification process more stably and efficiently, and to simplify the entire process .

In addition, the aerobic sludge bacteria can be co-cultured with microalgae to improve the treatment of organic pollutants.

1 is a graph showing removal rates of phenol with time in a method of treating coke wastewater using microalgae and bacteria according to the present invention.
FIG. 2 is a graph showing removal rates of ammonium nitrogen with time in a method of treating coke wastewater using microalgae and bacteria according to the present invention. FIG.
3 is a graph showing changes in chlorophyll concentration of microalgae over time in the method of treating coke wastewater using microalgae and bacteria according to the present invention.
FIG. 4 is a graph showing changes in removal rates, solubility chemical oxygen demand, and chlorophyll concentrations of phenol and ammonium nitrogen in a photo fermenter in a method of treating coke wastewater using microalgae and bacteria according to the present invention.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for culturing microalgae,

Culturing aerobic bacteria;

And removing the solid matter from the coke wastewater, and then inoculating the microalgae and the aerobic bacteria into the coke wastewater. The present invention also provides a method of treating coke wastewater using microalgae and bacteria.

The method of treating coke wastewater using microalgae and bacteria according to the present invention is a method of treating coke wastewater using microalgae and bacteria by using microorganisms such as Scenedesmus quadricauda resistant to phenol and cyanide compounds as microalgae, nitrogen (NH ₄ ⁺ -N), nitrate nitrogen (NO ₃ ^- N), and nitrite nitrogen (NO ₂ ^- N), which are nitrogen in photoautotrophic, heterotrophic or mixedotrophic conditions Can be treated directly without additional nitrification or denitrification processes. In addition, using microalgae, which are resistant to phenolic compounds and cyanide compounds, it is possible to treat nitrogen pollutants that have been difficult to treat in the conventional biological nitrification-denitrification process more stably and efficiently, and to simplify the entire process . In addition, the aerobic sludge bacteria can be co-cultured with microalgae to improve the treatment of organic pollutants.

The method for treating coke wastewater using microalgae and bacteria according to the present invention includes culturing microalgae.

At this time, the microalgae are resistant to phenol and cyanide compounds in order to treat coke wastewater. Examples of the microalgae include Scenedesmus quadricauda , Chlorella vulgaris), Mike Santini below Moth inner stops (Micractinium inermum), in the wrong ah (Ettlia sp.) can be used.

The microalgae are cultured in a Beigerinck's solution, a phosphate buffer solution, a Hunter's trace metal solution, and a Tris-acetate solution Tris-acetate phosphate (TAP) medium may be used.

The culture is preferably irradiated with fluorescent light of 100 to 140 μmol / m ² / s and stirred at 25 ° C. at 120 rpm.

Next, a method for treating coke wastewater using microalgae and bacteria according to the present invention includes culturing aerobic bacteria.

At this time, the aerobic bacterial community can be sampled and recovered from the aerobic reactor return water of the domestic sewage end treatment plant, and bio-pellets (biopellet) except for the supernatant after centrifugation are preferably used as seeds.

The method of treating coke wastewater using microalgae and bacteria according to the present invention includes the steps of removing solid matter from coke wastewater and inoculating the microalgae and the aerobic bacteria into the coke wastewater.

At this time, it is preferable that the coke wastewater uses raw water that enters the biological nitrification-denitrification tank, and the collected coke wastewater is filtered to remove suspended solids such as bacteria.

The microalgae and the aerobic bacteria community are preferably prepared by centrifugation so that initial concentrations of the microalgae and the aerobic bacteria are 150 to 1,500 mg / L. (NH ₄ ⁺ -N), nitrite nitrogen (NO ₂ ^- N), and nitrate nitrogen (NO ₃ ^- N) contained in the coke wastewater when the initial concentration is less than 150 mg / too much and the operating time is to be spent, respectively, of the case that the initial concentration is more than 1,500 mg / L ammonium nitrogen has blossomed is difficult to light is transmitted to the difficulty of photosynthetic microalgae (NH ₄ ⁺ -N) for processing, It is not possible to remove nitrite nitrogen (NO ₂ ^- N) and nitrate nitrogen (NO ₃ ^- N) to 100%.

Preferably, the inoculation is performed by irradiating light of 100 to 140 μmol / m ² / s and supplying CO ₂ at a concentration of ₂ to 15% at a flow rate of 0.20 to 0.30 vvm (gas volume per liter volume per minute).

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Example  1: Treatment of coke wastewater using microalgae and bacteria

1. Microbial seeds

Microalgae is a three or four des mousse Choir give the cow (Scenedesmus quadricauda) known to be resistant to a phenol and a cyan-based compounds were used as inoculum. Tris-acetate phosphate (TAP) medium containing Bayel's solution, phosphate buffered saline, Hunter's trace metal solution, and tris-acetate solution was used to culture seeds, and 120 μmol / m 2 ² / s of fluorescent light and stirred at 25 DEG C at 120 rpm.

Aerobic bacterial populations were sampled from the aerobic reactor return water of the domestic sewage treatment plant and centrifuged at 6000 g for 10 min. The biopellets were then used as seeds except for the supernatant.

2. Coke wastewater

The raw water entering the biological nitrification-denitrification tank in the coke wastewater treatment process was sampled and analyzed for properties. The results are shown in Table 1 below. The collected wastewater was filtered at 0.22 μm to remove suspended solids such as bacteria, transferred to a sterilized bottle, and stored at 4 ° C. Batch tests were conducted to evaluate the possibility of 100%, 80%, 60%, 40%, and 20% coke wastewater by dilution with distilled water.

Water quality analysis item value pH 7.8 Total solids (TS) (mg / L) 737.0 + - 7.8 Total suspended solids (TSS) (mg / L) 260.0 ± 14.1 Volatile solids (VS) (mg / L) 340.0 ± 28.3 Volatile suspended solids (VSS) (mg / L) 10.0 0.0 Solubility Chemical Oxygen Demand (SCODcr) (mg / L) 2,860 ± 42.4 Phenol (mg / L) 429 ± 9.2 Ammonium ^{_{(NH 4 +) -N (mg}} / L) 114.4 ± 4.5 Nitrate (NO ₃ ^- ) ^- N (mg / L) 6.9 ± 0.2 Nitrite (NO ₂ ^- ) ^- N (mg / L) Not detected Precyan (CN ^- ) (mg / L) 6.1 ± 0.8 Fluorine (F ^- ) (mg / L) 104.3 ± 0.9 Sulfate (SO ₄ ^{2 -} ) (mg / L) 999.6 ± 4.4 Sodium (Na ⁺ ) (mg / L) 1998.2 ± 52.9

3. Inoculation and culture

Micro-algae and aerobic bacterial populations were centrifuged and adjusted to an initial concentration of 200 mg / L. After inoculation with the prepared coke wastewater, S. quadricauda (microalgae alone) and S. quadricauda -aerobic sludge, microalgae-bacteria) were cultured and compared. The sample was irradiated with 120 μmol / m ² / s fluorescent light, and 2% CO ₂ was supplied at a flow rate of 0.25 vvm (gas volume per liquid volume per minute). Under light conditions of each condition, changes of organic pollutants and microalgae were observed. Culturing experiments were carried out in 250 mL flasks and the applicability was demonstrated by increasing the volume with a 4 L photofermentor.

Experimental Example  1: Analysis of phenol and ammonium nitrogen removal rate

1. Analysis of phenol removal rate

The phenol removal rates were compared and analyzed in the algal culture and algal-bacterial culture over time, and the results are shown in FIG.

As shown in FIG. 1, in the microalgae-bacterial culture, almost all the phenol was removed within 144 hours although the removal rate per hour was different according to the concentration of coke wastewater. In the microalgae cultivation, the higher the dilution ratio of the coke wastewater, the higher the removal rate of phenol. However, in order to completely remove phenol by microalgae alone, many dilution magnification and removal time will be required.

2. Ammonium Nitrogen Removal Rate Analysis

Ammonium nitrogen (NH ₄ ⁺ -N) removal rates in microalgae cultures and microalgae-bacterial cultures over time were compared and analyzed as shown in Fig.

As shown in FIG. 2, when ammonia nitrogen was diluted to less than 50% of the concentration of raw coke wastewater, almost all ammonium nitrogen was removed after 144 hours regardless of the presence or absence of aerobic bacteria. In the course of 94 hours, it was confirmed that nitrogen treatment efficiency was about twice higher than microalgae culture in microalgae-bacteria culture, which is a combination of aerobic bacteria and microalgae in 40% coke wastewater treatment. It is considered that aerobic bacteria eliminated the toxic organic substances including phenol present in coke wastewater, thereby improving the nitrogen treatment efficiency of microalgae. This result shows that the combination of microalgae alone or microalgae-bacteria can be applied to nitrogen treatment depending on the concentration of the coke wastewater influent.

Experimental Example  2: Analysis of microalgae growth

The degree of growth of microalgae was estimated by measuring the amount of chlorophyll change with time during the treatment of phenol and nitrogen, and is shown in Fig. It was confirmed that the chlorophyll content of the microalgae was increased more when the concentration of the coke wastewater was lower and the aerobic bacteria were present together. Since the degree of microalgae growth is inversely related to the amount of ammonium nitrogen treatment, it can be interpreted as a result of disproving that ammonium nitrogen is well treated by photosynthesis of microalgae. Especially, when microalgae grow with aerobic bacteria, .

Experimental Example  3: Analysis of Coke Wastewater Treatment Using Algae-Bacterial Culture

4 L of 20% coke wastewater was treated using algae-bacteria culture in a photofermentor by increasing the volume of the experiment and the results are shown in FIG. As in the flask test, it was confirmed that phenol and ammonium nitrogen (NH ₄ ⁺ -N) were removed. It was also confirmed that COD, which is an indicator of organic pollutants in wastewater, was removed by about 60%. In addition, a small amount of nitrite nitrogen (NO ₂ ^- N) was also present, but all of them were removed by microalgae (see Table 2). Of course, both the ammonium nitrogen and nitrite nitrogen, nitrate nitrogen in the aerobic condition ^- may seem as if the oxidation of (NO ₃ -N) up if removed, but before nitrate nitrogen ^- was not (NO ₃ -N) observed (see Table 2) . Nitrate (NO ₃ ^- N) could be reduced to nitrogen gas (N ₂ ) and removed under anaerobic conditions. However, since this experiment environment itself maintained the aerobic condition, nitrate Reduction from nitrogen to nitrogen gas (N ₂ ) can not occur. And it was confirmed that the micro-algae were growing, so that the nitrogen pollutants present in the coke wastewater were used as the nitrogen source necessary for growth under the photosynthesis condition of microalgae.

Water quality analysis item Content in initial wastewater Content after treatment SCODcr (mO ₂ / L) 645.0 + - 11.3 275.5 ± 8.5 Phenol (mg / L) 97.3 ± 3.6 Not detected NH ₄ ⁺ -N (mg / L) 20.2 ± 0.2 Not detected ^{_{NO 2 - -N (mg / L}} ) 1.4 ± 0.2 Not detected ^{_{NO 3 - -N (mg / L}} ) Not detected Not detected Chlorophyll-a (mg / L) Not detected 10.3 ± 0.2 DCW (mg / L) 10.0 0.0 1,180 ± 56.6

Experiments in the light fermenter have also been conducted in a batch mode, but various operations can also be performed by adjusting the hydraulic retention time (HRT) by switching to a continuous process based on the dilution ratio information obtained from the present study results.

Claims (8)

Culturing a microalgae;
Culturing aerobic bacteria; And
And removing the solid matter from the coke wastewater, and inoculating the micro-algae and the aerobic bacteria into the coke wastewater, wherein the micro-algae and the bacteria are used to treat the coke wastewater.
The method according to claim 1,
The microalgae may be selected from the group consisting of Scenedesmus quadricauda , Chlorella vulgaris , Micractinium inermum , and Ettlia < RTI ID = 0.0 > sp . ) Microorganism and a method for treating coke wastewater using bacteria.
The method according to claim 1,
Wherein the microalgae is cultured in a Tris-acetate phosphate (TAP) medium.
The method according to claim 1,
Wherein the aerobic bacteria are bio-pellets precipitated after centrifugation except for the supernatant. ≪ RTI ID = 0.0 > 8. < / RTI > The method of treating coke wastewater using microalgae and bacteria.
The method according to claim 1,
Wherein the concentration of the microalgae and the aerobic bacteria is 150 to 1,500 mg / L.
The method according to claim 1,
Wherein the coke wastewater is sterilized by removing the suspended solids from the filtration process and treating the coke wastewater using the microalgae and the bacteria.
The method according to claim 1,
Wherein the inoculation of the microalgae and the aerobic bacteria is carried out while supplying CO ₂ to the micro-algae and bacteria.
The method according to claim 1,
The microalgae and bacteria are characterized by removing phenol, ammonium nitrogen (NH ₄ ⁺ -N), nitrite nitrogen (NO ₂ ^- N) and nitrate nitrogen (NO ₃ ^- N) contained in coke wastewater to 100% And a method for treating coke wastewater using bacteria.

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