KR100285016B1 - Nitrogen and phosphorus removal from livestock wastewater and manure treatment in liquid corrosion method - Google Patents

Abstract

The present invention can be applied to TN, TP, BOD, and COD removal water quality standards that do not treat the high concentration organic wastewater such as manure and livestock manure, which occupy a large part as environmental pollution. The dewatered cake generated here relates to a method for removing TN, TP, COD and composting of high-concentration organic wastewater by liquid corrosion method that is made of high quality organic fertilizer and recycled by organic method or soil improving agent.

It is not sensitive to load fluctuations such as inflow amount and water quality because the organic organic wastewater is reacted while staying in the liquid corrosion tank for a certain period of time.

The high concentration organic wastewater is aerated for a certain period of time to oxidatively decompose various contaminants contained, and to stir in water for a certain period of time. The input flocculation reaction is performed to remove TP and remaining COD and to discharge the sterilization treatment in a daily cycle.

Description

Nitrogen and phosphorus removal method of livestock wastewater and manure treatment in liquid corrosion method

This invention is suitable to meet the water quality test standard by scientifically and economically treating nitrogen (N) and phosphorus (P) which are not treated well in the process of treating high concentration organic wastewater such as livestock wastewater and human manure by liquid corrosion method. The dehydrated cake produced from the treated water is organic fertilizer made from organic farming and recycled with a soil improver, and is related to the method of removing nitrogen (N) phosphorus (P) according to livestock wastewater and manure treatment.

Conventional livestock wastewater and manure treatment method (Environmental Notice No. 91-62 liquid corrosion method) mainly aimed at reducing BOD, SS, E. coli, and the application disclosed in the application number 92-13072 is to remove BOD, SS, TN, etc. In 1999, the standard of discharge water quality test is PH, BOD, COD, SS, TN, TP, E. coli.

Since the treatment result of the method does not meet the discharge water quality standards and items, the technique of the present invention is provided to obtain treated water that meets the inspection criteria.

Conventional treatment methods aim to reduce BOD, SS, TN, E. coli, etc. COD, TP, etc. are not properly treated and discharged, eutrophicated by an increase in nitrates and phosphates in streams, lakes and sea areas, which are discharged waters. The ton depleted the growth O ₂ , which polluted water resources such as odors from tap water and the death of fish.

Recently, all nitrogen (T-N), whole phosphorus (T-P), COD, etc. were regulated in the discharged water quality standards. Accordingly, as the necessity of advanced treatment is emphasized, the present invention is a nitrogen compound in the liquid corrosion method according to this need. And to provide a phosphorus compound and COD removal method.

In order to achieve the above object, the treatment method of the present invention basically uses the treatment method and the standard of the liquid corrosion method No. 91-62.

DO, PH, ORP detection sensor, temperature detection sensor, MLSS detection sensor at a certain position inside the liquid corrosion tank to perform the BOD removal process, nitriding, denitrification process of the present invention simultaneously or sequentially in the liquid corrosion tank It is characterized in that the aeration time and oxygen supply amount determined by the power pulse signal value applied from the interface unit for outputting the power pulse signal under the microcomputer control to detect the active state of the wastewater in the tank and control according to the detected value. .

1 is a livestock wastewater and manure treatment process diagram of the present invention

2 is a liquid corrosion tank automatic control of the present invention

3 is an operation control time schedule diagram of the liquid corrosion vessel of the present invention.

4 is a graph showing the effect of flocculant addition rate on the filtration ratio resistance of the sludge of the present invention.

5 is a graph showing the COD removal rate in the liquid corrosion tank of the present invention.

Referring to the treatment process of FIG. 1 for implementing this invention, it demonstrates dividing into five steps.

The first treatment process is a pretreatment process for livestock wastewater and manure to remove solid contaminants from the screen and to prevent sand wear and sedimentation in the tank.

Second treatment process: Homogenize pretreated livestock wastewater manure and transfer it to liquid corrosion vessel to remove BOD, COD and nitrogen. BOD removal process uses microorganisms in carbohydrates, fats, proteins, etc. Organic matter is removed in a quantitative relationship with CO ₂ and H ₂ O. The biological nitriding and denitrification process leads to nitriding and denitrification processes that convert nitrogen compounds in the wastewater into inert nitrogen gas by the action of nitrifying and denitrifying bacteria. Remove

The third treatment process: Residual COD and phosphorus removal process is to discharge phosphorus to the outside world in chemically and biologically bound state as insoluble precipitate, and adjust the pH to add the inorganic coagulant to remove the phosphorus compound by dehydration by dehydrator.

Fourth treatment process: Treated solid-liquid treated water is filtered and then filtered to remove residual suspended solids or sedimentation, and supernatant water meeting the water quality test standards is sterilized and discharged.

The fifth treatment step: The dehydrated cake treated in the dehydrator is fermented for a certain period of time to make organic fertilizer.

The water quality treated in the treatment step was obtained as shown in Table 1.

Item Circle wastewater Number of treatments Environmental standard PHBODCODSST-NT-P Escherichia coli 7.0 to 8.517,000 to 23,000 ppm3,500 to 6,000 ppm 2,000 to 4,000 ppm 6,000 to 6,500 ppm 700 to 1,000 ppm ³ x 10 ³ (MPN / 100 ml) 7 to 85 ppm 10 ppm 5 ppm 1 ppm 3 ppm 1000 (MPN / 100 ml) 7 to 830 ppm 60 ppm 30 ppm 6 ppm 18 ppm 3000 (MPN / 100 ml)

○ Example 1 T-N removal, BOD removal method

In order to satisfy the conditions of BOD removal and nitrogen removal of the liquid corrosion tank in the second treatment step of the treatment step, the present invention selectively agitates aeration in water to be aerobic for a predetermined time and a predetermined time for aerobic.

At this time, the ORP potential difference is -10 to + 20mv in the aerobic phase in the liquid corrosion tank, and the ORP potential difference is -200 to 300mv in the anaerobic state.

Where the BOD volume load is 0.8-1.4 kg / m 3. day

BOD.MLSS 0.1-0.4 kg / MLSS. Kg. Control operation by day.

At this time, BOD is removed while organic pollutants are removed according to the following mechanism.

- O ₂ → xCO ₂ + H ₂ O-△ H

- 5) O ₂

→ (C ₅ H ₇ NO ₂ ) n + n (x-5) CO ₂ + (y-4) H ₂ O-ΔH)

(Cytooxidation) (C ₅ H ₇ NO ₂ ) n + 5nO ₂ → 5nCO ₂ + 2nH ₂ O + nNH ₂ -ΔH

It automatically controls the aeration time set by the power pulse signal value applied from the micom and the interface outputting the signal according to the detected values such as PHIC, ORPIC, DOIC, MLSS sensor in the liquid corrosion vessel.

Here, in the aerobic state, when the BOD concentration of the wastewater is lowered and becomes 100ppm or less or the BOD is lowered, the nitriding proceeds rapidly.

In case of high BOD concentration, BOD oxidizing bacteria, which are other nutrients, become the dominant species.

Under aerobic conditions, ammonia nitrogen in wastewater is oxidized to nitrite by nitrite (Nitrosomonas, Nitrosococcus, etc.) and nitrite is further oxidized to nitrate by nitrate (Nitrobactor, etc.). have.

The isomerization proceeds in two stages.

NH ₄ ⁺ + 1.5 O ₂ → (Nitrosomonas) → 2H ⁺ + H ₂ O + NO ₂ + 66.5 kcal

^{_{NH 2 - + 0.5O 2 → (}} Nitrobactor) → NO 3 - + 17.5kcal

The total oxidation reaction of ammonia by the above two-stage equation (1) (2) is given by the following equation.

^{_{NH 4 + + 2O 2 → NO}} 3 - + H 2 O + 2H + + 84kcal

Nitriding bacteria are self-sustaining bacteria that reduce and propagate CO ₂ using "energy" obtained by oxidation of NH ₄ ⁺ or NO ₂ ^- without the need for organic matter for growth.

In the nitriding process, alkalinity is destroyed by oxidation of ammonia, producing carbon dioxide gas (H ₂ CO _{3 in} water), and 7.14 mg of alkalinity is consumed per 1 mg of ammonia nitrogen.

Nitrous oxidation of 1 kg of ammonia requires 3.43 kg and 1.14 kg of oxygen to nitrate 1 kg of nitrous acid.

The reaction of cell proliferation

^{_{5CO 2 + 55NH 4 + + 76O}} 2 → C 5 H 7 NO 2 + 54NO 2 - + 52H 2 O + 109H +

^{_{5CO 2 + 400NO 2 - + 195O}} 2 + NH 3 + 2H 2 O → C 5 H 7 NO 2 + 400NO 3 -

When 1 kg of NH ₄ ⁺ -N is oxidized, 0.147 kg of Nitrosomonas is synthesized. When 1 kg of NO ₂ ^- is oxidized, 0.02 kg of Nitrobacter is expanded.

The cell growth rate is considerably less than the growth rate of BOD oxidizing bacteria (0.5 ~ 0.7).

Under the anaerobic conditions of the denitrification process, it is reduced to nitrogen gas by the action of denitrification bacteria (Pseudomonas, etc.) that proliferates nitrite nitrogen and nitrate nitrogen.

This scheme is as follows.

2NO ₂ ^- + 6H ^- (organic _{material) → (Pseudomonas) → N 2} ↑

+ 2H ₂ O + 2OH ^-

2NO₃ ^-+ 10H^-(Organic) → (Pseudomonas) → N₂↑

+ 4H ₂ O + 2OH ^-

Defungal bacteria such as Pseudomonas are heterotrophic bacteria that require an organic carbon source (hydrogen donor) for proliferation, and are anaerobic bacteria that breathe oxygen under aerobic conditions and use oxygen in the NO ₃ ^- molecule under anaerobic conditions.

"Methanol" is used as a hydrogen donor in a general denitrification process, and this invention provides a denitrification reaction without using a separate methanol.

Especially when treating high concentration organic wastewater, scum injury may be a problem in the denitrification process.

In order to deal with this, in this invention, the scum removal apparatus is installed in the side of a tank.

Example 2 T-P removal, COD removal process

After the BOD removal and denitrification process in the first process, the daily capacity of sewage and wastewater is transferred to the second process to uniformly mix a certain amount, and then adjust the PH in the transfer coagulation reactor to adjust the conditions for good coagulation. Have it ready.

In this case, when the flocculant is added, the SS and the phosphorus compound are simultaneously aggregated, thus COD is also removed.

For this invention, 1.8 mg of iron ions (Fe ^3- ) are required, and the phosphate produced in 1 mg of phosphorus per 1 mg of iron ions is FePo ₄ 2.7 mgdl.

In addition, in the treatment method of the present invention, since alkaline component is present, the following reaction occurs.

_{FeCl 3 + 3HCO 3 → Fe (} OH) 3 + 3Cl - + 3CO 2

The hydroxide produced per mg of iron ions is 1.9 mg of Fe (OH) ₃ .

Since hydroxide is generated by reaction with alkali nitrile present in the wastewater, the metal salt-to-phosphorus Mole ratio (Fe: P, Al: P) to phosphorus is required to obtain treated water below the environmental standard value. Add.

In the present invention, aluminum salts or iron salts are effective as metal salts used for the removal of phosphorus (P), so that phosphorus forming a poorly soluble salt such as calcium is removed.

At this time, the operation was repeated with the new wastewater and the results obtained as shown in Table 2 were obtained.

The mechanism of phosphorus (P) removal is based on the following equation.

AL ³ + PO ₄ ^3- → ALPO ₄ ↓

Fe ³ + PO ₄ ^3- → FePO ₄ ↓

Metric aggregation BOD (%) COD (%) T-P (%) FeCl ₃ Ca (OH) ₂ Al ₂ (SO ₄ ) ₃ 88.889.5 not removed 73.873.0 not removed 40.097.124.896.8

○ Example 3 Composting Process

The dehydrated cake separated from the liquid-liquid dehydrator is transferred to the composting facility to adjust the input moisture, adjust the moisture first, then fermented completely in the secondary fermenter, and then screened in a screening device to convert to high quality compost. Package is shipped for easy adjustment, storage and storage.

Nitrogen and phosphorus removal method of the livestock wastewater and manure treatment according to the present invention is to install the pH, ORP, DO, temperature, MLSS detection sensor in the liquid corrosion tank and output the signal of the microcomputer and the microcomputer to control according to the detected value It is automatically controlled by the power pulse signal applied from the interface to selectively select the aerobic and anaerobic reactions respectively, remove BOD and TN according to biological activity, and provide TP and COD removal in the flocculation reaction process. It can be used for manure end treatment facilities as well as various industrial wastewaters.

Claims (2)

In the method of treating livestock wastewater or manure using liquid corrosion method, A detection device comprising a redox potential (ORP), dissolved oxygen (DO), temperature and mixed liquid suspended solids (MLSS) concentration detection sensor, an interface for outputting a power pulse signal corresponding to the detection value of the sensors, and microprocess control A wastewater from which solid particles are removed, using a process control system equipped with a liquid corrosion tank and a control device for maintaining the detected values of the sensors at respective preset values according to the power pulse signal value applied from the interface. BOD by biological liquid corrosion is inoculated with oxidizing bacteria, denitrifying bacteria and nitride bacteria in liquid corrosion tank for manure, and aerobic aeration and anaerobic agitation are carried out alternately so that the redox potential is 10-20mV and 200-300mV. And after the removal of nitrogen, the inorganic coagulant is added to the coagulation reactor to chemically coagulate the impurities. How to, nitrogen and phosphorus removal of livestock waste or manure, characterized in that performing the COD removal and phosphorus. The method of claim 1, wherein after dehydrating the aggregate formed in the flocculation tank, a fertilizer and a fermentation agent are added to the separated dehydrated cake to ferment and dry for a period of time to organically fertilize.