A METHOD FOR ENRICHMENT OF ANAEROBIC AMMONIUM

OXIDATION BACTERIA

Technical Field

The present invention relates to a method for rapidly enriching "Anaerobic Ammonium Oxidation" bacteria using activated sludge from wastewater treatment plants.

Prior Art

Ammonium removal, which is one of the most important parameters to be eliminated in the treatment of domestic and industrial wastewater, is now widely carried out by nitrification / denitrification processes. In the 1990s, the "Anaerobic Ammonium Oxidation_ANNAMMOX" bacteria was discovered by the Dutch Delf University. The said bacterium is used for ammonium removal from domestic and industrial wastewater in developed countries, especially in Europe and America, and its use is spreading under different process names. The most important advantages of using said bacteria over the nitrification / denitrification processes can be listed as; the reduction of energy use by almost 60%, elimination of the use of chemical as there is no need for the additional carbon source, low level waste sludge formation and the absence of C0 ₂ emission.,

However, the main disadvantage of said "Anaerobic Ammonium Oxidation" bacteria is that their growth rates are very slow. Optimum conditions are necessary for the enrichment of such bacteria in terms of mixture. Even though various periods of time are mentioned in the state of the art, generally 200 to 300 days are required for this process. There are no "Anaerobic Ammonium Oxidation" bacteria which can be proliferated as pure culture in the state of the art. For this reason, the enriched cultures taken from the other facilities, which have "Anaerobic Ammonium Oxidation" processes, are used as inoculum in the lab and/or pilot scale studies and in full scale plants. Activated sludge taken from conventional biological nitrogen removal plants can also be used as an inoculum. However, in this case the start-up phase can last for months or even years.

Activated sludge process is frequently used in the biological treatment of wastewater in the state of the art. This process, which is developed in 1914 by Ardern and Lockett in the UK, is called as activated sludge, due to the occurence of active mass production that can stabilize the waste aerobically. In the activated sludge processes, the wastewater coming from screening or primary settling tank is mixed with different amounts (20-100%) of the concentrated sludge coming from the secondary settling tank. This mixture is delivered to a aeration tank where the organisms and wastewater are aerated. By this process, the content is well mixed while the oxygen requirement of bacteria is met. Under these circumstances, while the organisms convert some of the organic matter to carbon dioxide, nitrogen gas and water to produce energy, the rest of the organic matter is used to produce new cells by using energy obtained in oxidation.

In Chinese patent document, numbered CN203112585, rapid enrichment reaction equipment is mentioned for "Anaerobic Ammonium Oxidation" (ANAMMOX). In the invention disclosed in said document, the reactor is a continuous stirred tank reactor containing a peristaltic pump and an inlet tank. At the base of this reactor, there is a water influent and effluent line. In the invention, there is also a thermometer and the temperature of the reactor is kept at 35 ±1. C. Brief Description of Invention

The aim of the present invention is to carry out a method for enriching the "Anaerobic Ammonium Oxidation" bacteria using activated sludge taken from wastewater treatment plants.

Another aim of the present invention is to carry out a method that enables "Anaerobic Ammonium Oxidation" bacteria to proliferate in a short period of time such as 60 days.

Detailed Description of the Invention

A method for the enrichment of the anaerobic ammonium oxidation bacteria to achieve the purpose of the invention; comprise the following steps:

-feeding of the reactor where an enrichment process will take place, with the active sludge comprising at least the heterotrophic carbon-removing bacteria that make carbon removal, autotrophic aerobic ammonium oxidation bacteria that remove ammonia in an aerobic environment; autotrophic nitrite oxidation bacteria that remove nitrite in an aerobic environment; heterotrophic denitrifying bacteria that convert nitrate to nitrogen gas (N ₂ (g)) in non-oxygen (in anoxic) environment, anaerobic ammonium oxidation bacteria that remove ammonium in the anaerobic environment, and phosphate accumulation bacteria that perform phosphorus removal and

-feeding of the reactor with nutrient solutions containing NH ₄ -N and N0 ₂ -N having a concentration of between 40 and 50 mg / L and nutrients and trace elements in predetermined concentrations in a preferred application of the invention, the content of nutrient solution is shown in Table 1 below: Table 1. The nutrient solution content in the exemplary application of the invention

Solution type Chemical substance Amount

(NH ₄ ) ₂ S0 ₄ 40 mg/L (NH ₄ ⁺ -N)

NaN0 ₂ 50 mg/L (N0 ₂ - -N)

KH ₂ P0 ₄ 0.0540 g/L

KC1 0.0014 g/L

Nutrient solution CaCl ₂ 0.0014 g/L

NaCl 0.0010 g/L

MgS0 ₄ 7H ₂ 0 0.0010 g/L

EDTA (C ₁₀ H ₁₄ N ₂ Na ₂ O ₈ 2H ₂ 0) 0.0050 g/L

Trace element solution I 1.25 ml/L

Trace element solution II 1.25 ml/L

Trace element solution EDTA (C ₁₀ H ₁₄ N ₂ Na ₂ O ₈ 2H ₂ 0) 5 g/L

I FeS0 ₄ 5 g/L

EDTA 15 g/L

ZnS0 ₄ 7H ₂ 0 0.430 g/L

CoCl ₂ 6H ₂ 0 0.240 g/L

MnCl ₂ 4H ₂ 0 0.990 g/L

Trace element solution CuS0 ₄ 5H ₂ 0 0.250 g/L

II Na ₂ Mo0 ₄ 2H ₂ 0 0.220 g/L

NiCl ₂ 6H ₂ 0 0.190 g/L

Na ₂ Se0 ₄ 10H ₂ O 0.210 g/L

H ₃ B0 ₄ 0.014 g/L

Na ₂ W0 ₄ 2H ₂ 0 0.050 g/L In the preferred application of the invention, the hydraulic retention time in the step of feeding the nutrient solution to the reactor is between 1 and 1.5 days.

In the preferred application of the invention, the nutrient solution is adjusted so as to contain concentration of 40 mg/L NH4-N and 50 mg/L NO2-N. Concentrations of NO2-N over 50 mg/L, slow down the anaerobic ammonium oxidation bacteria and stop the activity of these bacteria. In the preferred application of the invention, while preparing the nutrient solution, nitrogen gas was passed through the tap water to reduce the dissolved oxygen concentration below 0.1 mg / L. In a more preferred application of the invention, the concentration of dissolved oxygen in the tap water is brought into between 0.01 and 0.09 mg / L values while preparing the nutrient solution. Thus, when the dissolved oxygen concentration is above 0.1 mg / L value, it is ensured that the anaerobic ammonium oxidation bacteria, whose activities are slowing down or stopped, do not enter the internal respiratory phase. In the preferred application of the invention, while preparing the nutrient solution, the pH value of the solution is reduced to approximately 7 via nitrogen (N ₂ ) and / or carbon dioxide (C0 ₂ ); in a more preferred application of the invention the pH value of the nutrient solution is between 7 and 7.3. Thus, the negative effect of pH 8 or higher values, on anaerobic ammonium oxidation bacteria is prevented.

In the preferred application of the invention, while preparing the nutrient solution, C0 ₂ :N ₂ gas mixture at the rate of 10:90 is continuously supplied to the solution to keep the dissolved oxygen concentration constant and to keep the pH value at approximately 7.

In an alternative application of the invention, the pure N ₂ gas to prevent dissolved oxygen concentration from exceeding above 0.1 mg/L and the pure C0 ₂ gas to prevent the pH value of the solution from exceeding above 7, is manually supplied to the solution, while preparing the nutrient solution. In accordance with the method described above; experimental results related with the feeding of the nutrient solution with a dissolved oxygen concentration of less than 0.1 mg / L and a pH value of approximately 7, having a concentration of 40 mg / L of NH ₄ -N and 50 mg / L of N0 ₂ -N, and nutrient and trace elements with predetermined concentrations, to the activated sludge taken from the recycle line of a biological wastewater treatment plant previously into an upflow fixed bed reactor is shown in Graph 1 below. Accordingly, anaerobic ammonium oxidation bacteria are beginning to gain activity on the day of 60 . At the end of the day 110 ^th , depending on the PCR analysis results, it was observed that 10.48% of the sludge by weight was composed of anerobic ammonium oxidation bacteria, in addition to these, the amount of nitrogen removal reaches 1,48 kg/m ³ . day at the end of day 150 ^th .

Around these basic concepts, it is possible to develop a wide variety of applications related to the topic of invention "A Method for Enrichment of Anaerobic Ammonium Oxidation Bacteria" and the invention can not be limited to the examples described herein, it is essentially as specified in claims. Description of the Drawings

Figure 1. Graphic that shows analysis result of NH ₄ -N, N0 ₂ -N and N0 ₃ -N in an experiment made according to the method subject of the invention