KR20020035801A - Development of Soil Clothing-Style SBR for Sewage Treatment, Soil-SBR - Google Patents

Abstract

PURPOSE: A soil clothing-style SBR for sewage treatment, which has an effect of counterbalance of pH variations because nitrification/denitrification reactions is occurred in same reactor, can be provided in case of low alkalinity of sewage because that can prevent pH decline in nitrification reaction. The plants and soil microorganisms at the upper part of the reactor can purify the polluted materials by using them with nutrition. CONSTITUTION: The soil clothing-style SBR comprises a sequencing batch reactor(10) in which a filter layer(12) is installed at the upper part; a net(13) placed on the filter layer; a soil layer placed on the net; a sensor(15) which measures DO, pH, temperature and controls anaerobic/aerobic reactions by aeration; a PLC(20) which is transmitted the signal from the sensor; a computer(30) which controls aeration volume and aeration/agitation time with output unit by controlling the PLC. On the soil layer, plants such as grass that can provides soil microorganisms to the reactor is planted.

Description

Development of Soil Clothing-Style SBR for Sewage Treatment, Soil-SBR}

The present invention relates to a sewage treatment method, and more particularly to a soil-coated continuous batch sewage treatment method.

In recent years, eutrophication in closed waters such as lakes and coasts, which has become a major social problem, is caused by the influx of nitrogen and phosphorus compounds, which promote the growth of algae, phytoplankton in the water. Nitrogen and phosphorus compounds in water are themselves contaminants and cause loss of water resources, but they are used as nutrients necessary for algae growth and thus worsen water quality.

Therefore, since 1998, nitrogen and phosphorus items were added to the treatment plant effluent water quality standard (total nitrogen (N) = 60 mg / L, total phosphorus (P) = 8 mg / L), and from 2002, the water quality standard was defined as total nitrogen (N). = 20 mg / L, total phosphorus (P) = 2 mg / L.

Referring to the process of removing nitrogen or phosphorus as described above, first, the denitrification process includes a biosynthetic denitrification method using a hydrogen donor and an endogenous respiratory denitrification method using endogenous respiration of denitrified microorganisms. .

Biosynthetic denitrification is a method of using organic substances in untreated wastewater as a hydrogen donor and adding a chemical such as methanol or acetic acid.

Phosphorus removal methods are largely classified into chemical and biological methods. Chemical removal technology uses metal salts such as aluminum salts (Al ₂ (SO ₄ ) ₃ · 14H ₂ O) and iron salts (FeCl ₃ ) into water containing phosphorus to form insoluble phosphorus binders. It is widely used as a technique for precipitating and removing components.

The activated sludge process also allows the removal of phosphorus from BOD removal plants by adding metal salts to the final settling basin without adding a special facility.

Recently, a recognized stone method for making and removing phosphorus compounds into crystals has been developed and used. Phosphorus removal using such chemicals is excellent in terms of phosphorus removal efficiency, but generally has a disadvantage in that the operation cost is very high due to the cost of chemicals, and chemical sludge containing a large amount of phosphorus is generated.

Biological removal technology was developed to compensate for the drawbacks of chemical phosphorus (P) removal technology. The principle of phosphorus removal by this technique is very different from the removal of organic matter and nitrogen by microorganisms.

Phosphorus (P) is also an essential ingredient for the growth of microorganisms, so the amount used for microbial somatic cell synthesis is the same as sludge, but the main mechanism of phosphorus removal is the phenomenon caused by the excessive intake of phosphorus by microorganisms. In activated sludge, there is a poly-P microorganism which is a mainstream Acinetobacter species that can ingest excessive phosphorus.If the environment in the phosphorus removal reactor is changed repeatedly with anaerobic and aerobic state, the activity of Poly-P microorganism is relatively As a result, the intake of phosphorus increases accordingly.

This is called the over-phosphorus intake of microorganisms, and the principle of biological removal technology is to increase the phosphorus removal rate by removing microorganisms with high phosphorus content with sludge. Phosphorus content of ordinary microorganisms in activated sludge is usually 2-3%, while poly-P microorganisms are much higher, 5-10%.

Biological phosphorus (P) removal processes are largely divided into main stream processes and side stream processes. All inflows go through the anaerobic and aerobic processes in the mainstream process, and only part through the anaerobic and aerobic processes in the sidestream process. The A / O process is a typical initial phosphorus removal method. And some are disposed of as waste sludge.

This process can occur with nitrogen removal depending on the operation conditions of the aerobic tank, it is known that the operation is simple and the phosphorus removal efficiency is high.

On the other hand, Phostrip process is the end purpose of phosphorus removal and endogenous dephosphorization process that uses sludge sludge in anaerobic tank for a long time and uses organic material produced by cell decomposition as organic matter required for phosphorus discharge from dephosphorization tank. Not greatly affected by

However, the phosphorus released from the anaerobic tank in the Phostrip process is agglomerated and processed by the injection of slaked lime, which is expensive and cumbersome to operate. In addition, when the aeration tank of this process is operated for nitrification, phosphorus release from the dephosphorization tank is affected by the nitrates formed in the aeration tank.

As such, various treatment methods have been proposed to treat wastewater, such as domestic sewage.

In Korea, various types of SBR variants are made by changing the machinery or parts of the SBR process. Typical examples are the continuous inflow type and aerobic cycle extended aeration system (ICEAS). Batch Activated Sludge Process, Introduced to Yangyang Sewage Treatment Plant), Aqua-MSBR, Aqua-SBR, Omniflo-SBR, Swirl Swirl-BBR Activated sludge method (PSBR).

The treatment principles of these methods are all similar, but the biggest difference between them is the sewage inflow method and the mechanism. The first three methods use a continuous inflow method, while the next four methods use a batch (intermittent) inflow method.

The continuous inflow method does not necessarily require a flow adjustment tank, but the batch inflow method requires a flow adjustment tank. However, in the continuous inflow method, the water quality of the treated water is not stable. In particular, the treated water quality may deteriorate at a high concentration of sewage inflow. However, the batch inflow method is relatively stable in the quality of treated water.

The continuous inflow intermittent discharge type long-term aeration method (KIDEA) installs a localized decanter at the top of the reactor for easy maintenance, and installs a hollow pipe at the bottom of the SBR reactor to allow the inflow of raw water from the KIDEA process to flow into the tank evenly. Internal conveyance and agitator are not necessary due to the equal distribution of raw water by the piping system for the piping equipment.However, if the air supply is blocked by the front diffuser method, the reactor needs to be emptied for maintenance, and scum occurrence in the reactor is problematic. In addition, the precipitation efficiency is lower than the batch type because raw water is introduced in the precipitation process.

The reactor structure of the continuous batch activated sludge process (ICEAS), unlike other SBR methods, is dualized as a pretreatment reactor and a main treatment reactor. The pretreatment reactor is an organic selection tank that induces maximum biosorption by microorganisms, thus inhibiting the growth of filamentous bacteria that cause sludge bulking, removing substances such as milk fat, and preventing vortices of influent sewage during the treatment water outflow stage. Also perform.

However, because the pretreatment reactor is fixed as a civil structure, it is difficult to control when the flow rate and load fluctuate, and it is difficult to maintain because the front diffuser type, and the reactor must be completely empty during maintenance.

Aqua-MSBR is an SBR method developed by Aqua-Aerobic in the US and it is an advanced activated sludge process developed by adopting the advantages of the existing continuous inflow activated sludge process and SBR to treat heavy sewage wastewater. Very economical and effective. Aqua-MSBR has the features and advantages of SBR, as well as continuous inflow of raw water, continuous discharge of treated water, and constant surface maintenance in the tank.Aqua-MSBR divides one reactor into 5-9 cells, each cell containing organic matter, nitrogen, and phosphorus. It has an independent function to remove it.

Each cell is equipped with the necessary equipment according to its function. In addition, continuous inflow of raw water, continuous discharge of treated water, and constant sleep in the tank are possible, and one reactor is divided into 5-9 cells, and the cell has an independent function to remove organic matter, nitrogen, and phosphorus.

Aqua-SBR (Aqua-SBR) method increases the energy saving effect by improving the oxygen transfer capacity by installing agitator in addition to the aeration device.However, the removable acid engine, DDM-MiXER (Aqua-Aerobic, USA) It is difficult to maintain and maintain the reactor in case of several reactors because it is divided into three devices such as direct-drive mixer and floating decanter.

Omniflo-SBR is a SBR (Sequencing Batch Reactor) system developed by the US (US FILTER / JET TECH Co., Ltd.), which is used for inflow, reaction, sedimentation, treatment water discharge and idle. A step process is a process performed sequentially in one reactor. By discharging the sludge evenly and stably with ID / SC distribution pipe, the water content of the waste sludge can be lowered. The non-powered floating decanter is used for easy maintenance, and the use of jet aerator keeps oxygen transfer efficiency even during long-term use.

However, in order to prevent the closing of the jet injection nozzle, it is necessary to install a fine screen on the settlement, and the machinery / piping of the recirculation pipe, the aeration device cleaning facility, etc. is complicated.

Swirl Vortex-SBR method is simpler than the method using diffuser by installing and operating surface stirrer which performs aeration and agitation function simultaneously. There is a problem that the number of.

Pumyang Continuous Batch Activated Sludge Process (PSRB) is a process that improves the ability to remove sewage, nitrogen and phosphorus in sewage and maximizes the discharge rate per cycle. There is a decanting system that can secure stable treated water quality without disturbing.

When the sludge conveying process is completed, the discharge ratio is controlled by raising and lowering the curtain wall of the discharge reserve chamber, and the discharge reserve chamber secures the sludge settling layer by the fixed wall and the moving wall, and operates a preliminary pump in case of failure. You can carry out parallel processing and repairs.

The PSBR method is a pressurized discharge by the pump, which incurs additional costs in maintenance of power consumption compared to the general system based on the natural discharge method, and increases the number of pumps for sludge transfer and discharge functions including reserves. The machine room must be installed, and the piping is complicated, and the discharge pump has to handle up to the flow rate in the rain, so that the capacity of the rear end equipment is increased, and the curtain wall inside the reactor for the automatic control must be driven electrically. have.

In addition to the various sewage treatment methods described above, there are a variety of methods, but recently, a sequencing batch reactor (SBR) method has been developed. The method based on the initial batch method is Thomas Wardle of England in 1893. It was first proposed by Sir.

Since then, it has been used on a small scale by Meling and Suckworth in 1914, and it can automatically open and close a large amount of influent wastewater due to the rapid population growth and industrialization of the city since the 1930s. ) And other subsidiary facilities, the development of which is no longer possible. Since then, the development and practical use of automated valve systems, electrical timers and other water level control devices have become possible.In the 1950s, Sequencing Batch Reactor (SBR) was developed by Hoover and Porges. After the 1970's, Irvine began to attract attention as the superiority of the SBR method was confirmed by Irvine.

Non-SBR-based methods divide each reactor in a spatial manner, but SBR combines the spatially divided reactors into a single reactor to allow each reaction to proceed in the order of time. In other words, in SBR, inflow, anaerobic, aerobic, sedimentation, and discharge are performed in order of time in one reactor.

SBR combines spatially partitioned reactors into a single reactor, allowing each reaction to proceed in chronological order. In other words, SBR inflow, anaerobic, aerobic, sedimentation, discharge in one reactor is made in the order of time.

1) Fill: During the inflow period, the sewage is filled with the desired volume as it comes into contact with the microorganisms remaining in the reactor. The inflow volume can be determined within 30-75% depending on the nature of the sewage. There are three main types of inflows: static fills, mixed fills, and aerated fills. Among them, the mixed inflow method is most commonly adopted. In the case of the mixed inflow, the anaerobic reaction takes place during the inflow period, so that denitrification and phosphorus emission are performed, resulting in an improvement in treatment efficiency.

2) React: The reaction period consists of aerobic reaction time to supply oxygen and anaerobic or anoxic reaction time without oxygen supply. During this time, not only organic matter but also nitrogen and phosphorus can be simultaneously removed. The reaction time is operated at about 50% or less of the total time in one cycle, and the reaction time is periodically repeated an aerobic / anaerobic state.

3) Settle: This is the step of separating solid-liquid from mixed liquid and has high settling efficiency because there is no flow of influent during settling period. SBR is directly related to improvement of treatment efficiency because sludge precipitated without recycle of sludge remains as microorganism for reaction in the next cycle. Generally, if the load of influent is not high, the settling time is about 0.5-1.5 hours.

4) Draw: The discharge uses a fixed discharge pump or a floating discharge pump, and various other discharge methods are used. In particular, in the discharge step, it is important to stabilize the water quality of the treated water so that the sedimented sludge is not shaken because the purpose is to discharge only the supernatant separated from the solid solution.

The characteristics of the SBR method are to calculate the aeration time in the SBR treatment system.The basic characteristics of the influent water, the amount of water treated in one cycle, the capacity of the reactor, the shape of the reactor, and the MLSS in the tank are used to calculate the aeration time in the SBR treatment system. System operating factors such as concentration, aeration intensity, oxygen transfer rate, and target removal rate for each item should be considered at the same time.

In the SBR treatment system, when the removal of nitrogen should be prioritized due to the characteristics of the influent, the aeration time and aeration intensity are increased to maintain sufficient nitrification (at least 1 mgO ₂ / L dissolved oxygen is maintained), and the removal of phosphorus is more important. Should be maintained at 0.5 mg / L. In the application of SBR for nitrogen removal, attention should be paid to controlling the aeration time so that the organics necessary for the denitrification reaction are present in the reactor.

In addition, by repeatedly changing the environment in the anaerobic and aerobic state in a single reactor, the uptake of phosphorus (Luxury Uptake) of the microorganisms is increased to increase the amount of phosphorus removal.

However, the SBR method has not been activated because it requires a highly automated operation system, but these problems have been overcome by generalization of automation technology and have been widely used in recent years. Common advantages of the SBR process include: (1) small footprint and simple process, (2) instantaneous high flow rates or pollutant loads, (3) transportation and transport costs are low because no transport of sludge is required, and (4) ) There is no bulking due to the inhibition of filamentous fungi due to the alternating aerobic and anaerobic conditions in a single reactor. (6) Sludge bulking is unlikely to occur. In particular, by maintaining the inflow period of the waste water in the anaerobic state, the SVI is lowered and the energy cost of the aeration is also reduced.

In addition, the nitrogen removal method is largely divided into physical and chemical methods and biological methods. Physical and chemical methods include ammonia stripping, discontinuous chlorine injection, ion exchange, reverse osmosis, and electrodialysis. These include installation and operating costs, environmental impact, and treatment of concentrated water generated during regeneration. Is rarely used.

On the other hand, biological methods are widely used as nitrogen removal techniques in water because their principles are elucidated to some extent, and cost, environmental problems, and by-products are rarely generated compared to physical and chemical treatment methods.

However, the SBR method is a commonly used method for removing organic matter, but it can be removed together with nitrogen depending on the operating conditions and has been reported to have high efficiency. However, in the application of SBR for nitrogen removal, it is necessary to pay attention to the aeration time. The organic matter necessary for the denitrification reaction must be maintained in the reaction tank through the control of. In addition, the environment is repeatedly changed to anaerobic and aerobic conditions in a single reaction tank, resulting in the uptake of microorganisms due to excessive uptake of microorganisms. Care should be taken to increase.

Although various sewage treatment methods have been developed as described above, the SBR method has been in the spotlight in terms of environmental aspects, installation space, and maintenance and maintenance costs, but it has not been put into practical use.

According to the present invention, since the nitrification reaction to lower the pH and the denitrification reaction to raise the pH occur in the same reactor, the pH increase and the effect of offsetting the increase and decrease of each other can be obtained. The purpose is to provide a SBR method when the alkalinity level that can be prevented is very low.

An object of the present invention is to provide the following to improve the processing efficiency of the process.

As the SBR method, the batch water of the treated water is more stable than the continuous method, and in the past, a decanter (a symbol discharge device) has to be installed due to the sludge bulking occurring on the surface of the reactor, but in this method, the soil microorganism By covering the porous soil inhabiting this many species, the treatment function was maintained by the soil microorganisms without installing a decanter.

Even if microorganisms in the reactor die due to abnormalities in the inflow water quality or breakdown of the air supply system, the microorganisms in the soil layer are naturally supplied by covering the porous soil on the upper part, so no artificial supply is required. Deodorizers are also unnecessary.

In order to increase the nitrogen removal rate, it is necessary to keep the hydraulic residence time as short as possible in treating the same amount of influent, and to allow more anaerobic reaction time in the time allocation of the anaerobic and aerobic reactions that occur repeatedly in one cycle. Lengthened.

When the DO concentration in the reactor is high when the aerobic reaction is converted to anaerobic reaction, the conversion time is longer and the anaerobic reaction (denitrification) time is reduced by that amount. Various sensors were installed in the reaction tank so as not to exceed ˜2 mg / ℓ), and the pH, DO, and temperature were monitored and controlled by remotely monitoring and controlling the signals detected by the sensors.

In order to increase the amount of phosphorus removed, the repetition time of anaerobic and aerobic cycles is shortened as much as possible within a given reaction time, thereby increasing the number of repetitions, thereby increasing the cell uptake due to excessive intake of phosphorus due to the stress of microorganisms. There is a purpose.

In addition, the reaction immediately before the settling time at the end of one cycle aims to improve the efficiency of phosphorus by setting the anaerobic / aerobic repetition cycle so that the aerobic reaction to absorb the phosphorus comes.

1 is a detailed view of the reactor according to the present invention,

2 is a view showing the operating status for each sample of the reaction tank according to the present invention,

3 is an overall configuration diagram of an automated operation PLC (Programmable Logic Controller) according to the present invention;

4 is a block diagram of a monitoring system according to the present invention.

<Description of Signs of Major Parts of Drawings>

10: reactor 11: soil layer

12: Media layer 13: Maternal network

15: automatic measuring instrument

20: Programmable Logic Controller

30: computer

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

In order to achieve the object of the present invention, as shown in Figure 1, a batch-type SBR process is combined with the soil purification method, a natural method. In other words, the porous soil was coated on the upper part of the reactor 10 and the grass was planted thereon to use the natural purification function of the soil and the plant. As a result, the soil layer 11 placed on the upper part of the reactor and the grass thereon can increase treatment efficiency by serving as an auxiliary function for treating pollutants using BOD, TN, TP, etc. together with soil microorganisms as nutrients. It became.

In addition, when microorganisms in the reaction tank 10 are killed due to abnormalities in the inflow water quality or failure of the air supply device, the microorganisms in the soil layer 11 (soil ecological layer) may be naturally supplied into the reaction tank 10. Even if the microbial culture tank is not separately installed, the soil layer 11 may replace this role.

As such, organisms such as plants, animals, and microorganisms live in the soil layer 11 while maintaining interdependence. In particular, the odor generated in the reaction vessel is adsorbed while passing through the porous soil layer on the upper side, the adsorbed odor substance may be gradually converted into a odorless material by soil microorganisms, the top of the reaction tank 10 to a vegetation plant such as grass It is covered and can be used as a member of landscaping facilities.

A capillary network 13 is installed between the reactor media layer and the soil layer 11 to fix the capillary network so that the soil does not fall to the bottom, and using crushed stone (φ100 to 150) to the bottom of the soil layer to a depth of 20% of the total capacity. Filled.

The filter media layer 12 may not only connect the sewage and soil layers introduced into the reactor, but also remove some of the contaminants in the sewage by the microorganisms attached to the filter media.

It also includes the ability to mitigate the impact of water on the bottom of the soil layer as it is stirred in the reactor.

The reason for using the crushed stone as the filter media filler is because it is economical and easy to obtain in nature, and it is determined that the soil microorganisms can give the closest condition to grow not only in the soil layer 11 but also inside the reactor.

The lower filter layer 14 is to perform the same function as the SBR. In other words, the state of the reaction tank is changed to the role of inflow tank / aerobic tank / anaerobic tank / sedimentation tank according to the time zone. The sewage inflow method used a batch (intermittent) inflow method, but in the present invention, the inflow sewage was continuously injected into the two reaction tanks in different time periods.

The aerobic reaction, anaerobic reaction and the biological or chemical reaction according to nitrogen and phosphorus removal according to the present invention will be described.

※ About aerobic reaction,

Aerobic microorganisms decompose organic matter to obtain energy and synthesize cells, which are expressed as follows.

COHN (organic) + O ₂ + nutrients → C5H7O2N + CO ₂ + NH ₃ + other products

As shown in the above equation, organic matter in waste water is converted to new cells of microorganisms (C ₅ H ₇ O ₂ N), CO _2, etc. and removed. At this time, 0.12 kg of nitrogen and 0.025 kg of phosphorus are consumed to synthesize 1 kg of C ₅ H ₇ O ₂ N.

Anaerobic reaction

The process of decomposition of organic matter by anaerobic microorganism can be divided into two stages. The first organic material by the acid producing bacteria in the step of acetic acid (CH ₃ COOH), or as will be converted into an organic acid such as propionic acid (CH ₃ CH ₂ COOH) is ammonia (NH ₃₎ is generated in addition to the organic acid in the course of decomposition in the case of a protein . In the second stage, the organic acid produced in the first stage is converted by the methane producing bacteria into the final products methane and carbon dioxide. Since the growth rate of organic acid producing bacteria is fast while the growth rate of methane producing bacteria is slow, the efficiency of wastewater treatment by anaerobic method is dependent on the role of methane producing bacteria rather than organic acid producing bacteria. The process of decomposition of organic matter by methane-producing bacteria is as follows.

COHN (organic) + H ₂ O + Nutrients → C ₅ H ₇ O ₂ N + CH ₄ + CO ₂ + NH ₃ + HCO ₃ + Other products

As shown in the above equation, the organic matter is converted to C ₅ H ₇ O ₂ N, CH ₄ , CO _2, etc. by methane producing bacteria.

Nitrogen removal theory

The predominant nitrogen forms for wastewater are organic nitrogen and ammonia nitrogen (NH ₃ -N). Organonitrogen is converted to NH ₃ -N by the decomposition of microorganisms under anaerobic or aerobic conditions. NH ₃ -N is converted to nitrate nitrogen (NO ₃ -N) via nitrite nitrogen (NO ₂ -N) by a microorganism oxidizing it.

This oxidation process of NH3-N is called nitrification, and NO ₃ -N produced by nitrification is reduced to nitrogen gas (N ₂ ) and released into the atmosphere by microorganisms that reduce it. Denitrification).

Nitrification Process

There are many kinds of microorganisms that cause oxidation of ammonia, but the representative ones are Nitrosomonas and Nitrobacter . These are all aerobic autotrophic Bacteria and grow by oxidizing ammonia with oxygen. The nitrification of ammonia in water in the form of ammonia ions (NH ₄ ⁺ ) is as follows.

^{_{22NH 4 + + 37O 2 + 4CO}} 2 + HCO 3 - → C 5 H 7 O 2 N + 21NO 3 - + 20H 2 O + 42H +

Nitrification has a very low cell yield produced by the oxidation of ammonia compared to heterotrophic Bacteria. Nitrogen microorganisms, which are independent nutrients, have a much higher proliferation rate than heterotrophic microorganisms that decompose organic matters. Therefore, if the concentration of organic matter is high in the wastewater, the proliferation rate of heterotrophic microorganisms that decomposes it is difficult to accumulate nitrifying microorganisms in the reactor.

In addition, since nitric oxide (H +) is generated in the nitrification process, the nitrification rate may be reduced due to the pH decrease in water. The optimum pH for nitrification is a narrow range between 7.5 and 8.6, but in the case of microorganisms adapted to lower pH, nitrification can be successful even at low pH.

However, when the pH is lowered below 5, it is known that nitrification no longer occurs. Therefore, in order to maintain an appropriate pH in the reactor, it is necessary to supply 7.14 mg of alkalinity (as CaCO ₃ ) per 1 mg of ammonia nitrogen.

※ Denitrification Process

Denitrification refers to a process in which nitrates (NO ₃ ) generated during nitrification are reduced to harmless nitrogen gas (N ₂ ). In the denitrification process, since NO ₃ ⁻ is used as a hydrogen acceptor, it becomes an anaerobic reaction. In the case of supplying methanol as a carbon source, the biological equation for removing NO 3 is as follows.

^{_{NO 3 - + 1.08CH 3 OH +}} H + → 0.065C 5 H 7 O 2 N + 0.47N 2 + 0.76CO 2 + 2.44H 2 O

Denitrifying bacteria include species such as Pseudomonas, Micrococcus, Archomobactor, Bacillus, etc. Since these microorganisms are facultative heterotrophic microorganisms, denitrification does not occur because molecular oxygen is used as an electron acceptor. Therefore, in order to activate the denitrification, an oxygen-free environment and supply of sufficient organic matter are absolutely necessary. Methanol is the most widely used organic material for denitrification because of its economic feasibility. However, if a useful alternative is obtained in the waste water, the cost of supplying methanol can be reduced.

Denitrification is reported to have an appropriate pH of 7 to 7.5 and denitrification is inhibited when the pH is 6 or less or 8 or more. However, Pseudomonas et al. Are known to be denitrified even at pH 5.8-9.2. In the denitrification process, as opposed to nitrification, the pH of the water rises because it consumes rather than releases hydrogen ions. In order to properly utilize these effects, a method of placing a nitrification reactor behind the denitrification reactor and internally circulating the nitrification liquid into the denitrification reactor has been widely applied.

※ phosphorus removal theory

Phosphorus content in the cells of the microorganism is about 1.5 to 2% by dry weight ratio, so biological removal is rarely performed under normal circumstances. However, when the environment in the reactor repeats anaerobic and aerobic conditions, phosphorus intake by microorganisms (PAOs, phosphate accumulatingorganisms) increases, which is called luxury uptake of microorganisms. Phosphorus is finally removed by sludge removal of microorganisms with high phosphorus intake. The main dominant species of PAOs has been found to be Acinetobacter.

PAOs utilize the energy generated when the orthophosphate polymers (poly-phosphate) accumulated in the cell in the anaerobic state are decomposed and released into phosphate ions to convert organic matter into cells in the form of poly-β-hydroxybutyrate (PHB). In the aerobic state, phosphate ions (orthophosphate) are ingested from the outside while being decomposed into oxygen by PHB and stored in the cell in the form of poly-phosphate. Therefore, in order to increase the phosphorus removal rate, it is preferable to remove the sludge immediately after passing through the aerobic state. Anaerobic conditions can be a serious deterrent to aerobic microbes that breathe only with oxygen.

However, PAOs are slow in growth and can only be used for carbohydrates. However, repetition of aerobic and anaerobic conditions is advantageous for PAOs that can store and extract energy from polyphosphates. That is, when only aerobic conditions are maintained, growth of PAOs is inferior to general aerobic microorganisms, but general aerobic microorganisms and PAOs may compete in a situation where the aerobic and anaerobic cycles are periodically repeated. In more detail, the process of phosphorus release and phosphorus intake by PAOs is as follows.

※ Phosphorus release process

In the anaerobic phosphorus release process, most of the acetic acid (HAc) is present in the ionic state at normal pH conditions, and high concentrations of Acetate (Ac) are passively diffused into the cells.

Phosphorus Release Process in Anaerobic Conditions

HAc passively diffused into cells is converted to acetyl-coenzyme (acetyl-CoA, AcCoA) using energy generated when Poly-P is decomposed to release phosphate ions, and part of the generated AcCoA is TCA (tricarboxylic acid). It produces NADH (reduce nicotinamide adenine dinucleotide) and stores it in PHB form using the remaining NADH. It has been reported that the concentration of nitrate (NO ₃ ) has a significant effect on phosphorus release under anaerobic conditions, and the higher the concentration of nitrate, the lower the phosphorus release rate. This is because some of the phosphorus-removing microorganisms (denitrifying PAOs) that store Poly-P and PHB in the absence of oxygen (O ₂ ) use NO ₃ as the final electron acceptor, consuming PHB and not phosphorus release. Because it reproduces.

※ phosphorus intake process

As shown in the figure below, the phosphorus intake process in aerobic state is anaerobic and the phosphorus removing microorganism becomes aerobic or anaerobic, and when there is an electron acceptor such as O ₂ or NO ₃ , PHB stored in the cell Convert to Acetyl-CoA.

Phosphorus intake process in aerobic conditions

Acetyl-CoA produces NADH2 through the TCA circuit, and NADH2 is oxidized to form the energy source ATP necessary for cell synthesis and resynthesis of Poly-P. Therefore, the intake of phosphorus from the outside occurs to continue to supply the ATP required for this synthesis process. Dissolved oxygen (DO) is required when decomposing organic materials to obtain the energy needed to store phosphate ions in the form of poly-P in the cells of microorganisms. If the load of organic matter is low, the phosphorus release occurs at 0.3 mg / L or less. If the load of organic matter is high, phosphorus release starts at 0.1 mg / L or less.

※ Biopurification theory by soil

Up to about 1 meter below the soil surface, organisms such as plants, animals, and microorganisms live in interdependence. When contaminants enter the soil layer, the contaminants become nutrients to soil organisms and are decomposed and removed. Earthworms, especially earthworms, are very fond of sludge as is commonly seen in general sewers, and have the ability to break down sludge by passing their weight into their bodies every day.

On the other hand, harmful bacteria in wastewater, such as E. coli, have mutual relations with soil microorganisms, which can be completely eliminated by feeding on soil microorganisms.

The main equipment specifications of the wastewater treatment field test apparatus and the test apparatus used in the present invention are summarized in Table 1 and Table 2 below.

Major facility functions and specifications of field test equipment Name Specification Reactor Standard Effective Capacity 0.6 × 0.3 × 1.0 (m) 0.1㎥2 set Air Blower Quantity 2 units Flow Control Pump Quantity 2 units Soil layer Thickness surface 0.15m grass vegetation Filling Media Material Pole Rate Roasted Yellow Clay Pipe Piece 0.46 PLC standard Master-K series (K10S) Automatic measuring machine standard DO, pH, temperature meter

SBR reactor design capacity division Volume Flow rate (Q) 0.025㎥ × 4cycle / day × 2 sets Volume (V) 0.1㎥ × 2 set HRT 24hour MLSS 3000-3500 mg / ℓ Cycle 6hour4cycle / day Media layer volume 0.02㎥ × 2 sets SBR reactor volume 0.08㎥ × 2 set Total volume 0.1㎥ × 2 set

The total number of reactors was two, and the treatment capacity of each reactor was based on 0.1 m 3 / day. The design details of the reactor are shown in Table 2 above.

The reactor was manufactured using an acrylic plate, and as shown in FIG. 1, the upper part of the reactor was used to grow soil layers and grasses thereon, thereby improving the pollutant purification function by using the soil and plant natural purification functions.

In other words, the soil layer placed on the upper part of the reactor and the grass on it will be able to increase the treatment efficiency by serving as an auxiliary function of treating pollutants using BOD, T-N, T-P, etc. together with soil microorganisms.

In addition, microorganisms in the soil layer (soil ecological layer) can be naturally supplied into the reactor when the microorganisms in the reactor die due to abnormalities in inflow water quality or failure of the air supply device. Soil layer can take over. As described above, organisms such as plants, animals, and microorganisms live in the soil layer while maintaining interdependence.

In particular, the odor generated in the reaction vessel is adsorbed while passing through the porous soil layer on the upper side, the adsorbed odorous substance can be gradually converted into an odorless substance by soil microorganisms, and the top of the reaction vessel is covered with vegetation plants such as grass. It can also be used as a member of landscaping facilities.

A capillary network was installed between the upper part of the reactor and the soil layer to prevent the soil from falling to the bottom.

Such a filter bed may not only connect the wastewater and the soil layer introduced into the reactor, but also remove some of the pollutants in the wastewater by the microorganisms attached to the filter medium. It also includes the ability to mitigate the impact of water on the bottom of the soil layer as it is stirred in the reactor.

The reason for using the ocher tube as the filter layer filler is that the ocher tube is almost similar to the soil component, and it was determined that the soil microorganisms could give the closest condition for growth not only in the soil layer but also inside the reactor.

The lower layer of the filter media was to perform the same function as the Sequential Batch Reactor (SBR). In other words, the state of the reaction tank is changed to the role of inflow tank / aerobic tank / anaerobic tank / sedimentation tank according to the time zone.

The sewage inflow method used a batch (intermittent) inflow method, but the inflow sewage was continuously injected into the two reaction tanks used in the present invention in different time periods.

In addition, in order to confirm the effect of the internal agitation of the reactor, the first reactor caused internal agitation at the anaerobic reaction time using a stirrer, and the second reactor did not install the internal agitation during the anaerobic reaction time because no agitator was installed. It was not. However, during the aerobic reaction time, internal agitation occurred in both reactors by injection of bottom air.

By operating the reactor according to the present invention as described above was performed as follows.

Influent sewage concentrations of major water quality items are CODcr 169.9 to 401.9 mg / L, BOD 85.0 to 211.5 mg / L, SS 66.0 to 238.0 mg / L, TN 37.1 to 75.1 mg / L, NH3-N 17.6 to 48.6 mg / L, NO3--N 0.0-4.6 mg / L, TP 2.6-8.6 mg / L, PO4-P 2.4-5.5 mg / L.

The operating conditions of this experiment focused on the removal of nitrogen phosphorus rather than organic matter removal. The experimental unit was operated under four different conditions, with a total cycle of 4 cycles / day and a reaction time of 6 hours / cycle. 6 hours / cycle is suitable for small wastewater treatment, but 4 hours / cycle is generally used at low concentrations. And when manure is mixed and the concentration of influent is gradually increased, the reaction time is increased to 8 hours / cycle, 12 hours / cycle, and 24 hours / cycle as well.

In the present invention, the reactor was operated at 6 hours / cycle based on small scale wastewater treatment. In this condition, the inflow time was 20-30 minutes / cycle, the reaction time was repeated anaerobic and aerobic, and the precipitation was set to 40 minutes / cycle in common.

Inflow Concentration Status Unit by Step (mg / L) Step Item Above standard value Sample 1 Sample 2 Sample 3 Sample 4 CODcr 169.9 to 401.9 208.8-305.2 224.9-452.7 162.1 to 270.6 223.9-250.9 BOD 85.0-187.5 103.6-151.2 120.7 to 211.5 87.5-127.3 120.2-146.0 SS 87.0-200.0 66.0-115.0 102.0 to 238.0 74.2-128.0 114.5-137.5 T-N 38.8 ~ 64.3 37.1 to 63.1 51.3 ~ 75.1 44.8 to 68.2 52.7-60.4 T-P 2.6-8.6 4.2-7.0 4.1-6.0 3.7 to 4.5 3.5 to 4.1 NH3-N 18.6-40.9 17.6 to 30.6 34.5-41.0 23.5 to 48.6 29.1 to 34.6 NO3-N 0.0 to 4.1 2.3 to 4.6 3.2 to 4.2 2.6 to 3.4 2.3-3.1 PO4-P 3.2 to 5.5 3.2 to 4.9 3.1 to 4.1 2.9 to 3.6 2.4 to 3.1 Water temperature 10.5-22.5 ℃ 15.3 ~ 25.6 ℃ 18.4 ~ 27.6 ℃ 27.1 ~ 35.4 ℃ 30.2-35.1 ℃ Alkalinity 164.9-245.6 154.8-204.8 212.4 to 257.4 175.6 ~ 278.4 205.6-224.5

The discharge was allowed to operate simultaneously with the inflow. The operating conditions were classified according to the change in the time of inflow / expiration / anaerobic / sedimentation and the order of anaerobic / exhalation within one cycle, and the hydraulic residence time of Samples 1 to 3 was 24 hours, and Sample 4 was 18 hours . On the other hand, MLSS concentration in the reaction tank was to maintain about 3000 to 3500mg / L.

Water analysis method Samples were collected and analyzed at a frequency of about once a week, and the sampling points were inflow and outflow. However, samples were analyzed for each time period during which anaerobic and aerobic cycles were repeated within one cycle (6hour / cycle) before the operating conditions of the reactor were changed.

In order to understand the characteristics of influent sewage treatment according to the change of each operating condition, the water quality items measured regularly are CODcr, TN, NH3-N, NO3--N, TP, PO4-P, SS, BOD, pH, temperature, DO to be.

Among these items, pH, temperature, and DO were measured in the field using a portable device. The remaining items were taken in an ice box and transported to a laboratory, followed by environmental pollution test method and US standard method (Standard). Method). The analysis method for each item of water quality analysis is shown in Table 4.

Analysis method by water quality item Items Testing methods (Methods) and devices pH pH / mv meter (Fisher Scientific Accument 1003) DO (Dissolved Oxygen) O'Brein dlectrode method (YSI model 51B) CODcr (Chemical Oxygen Demand) Closed Reflux Titrimetric method (Standard Methods) Biological Oxygen Demand (BOD) 5-Day BOD Test (YSI model 51B) T-N (Total Nitrogen) Environmental pollution official method (Korea) Shimadzu UV-1601 UV-Visible Spectrophometer T-P (Total Phosphorus) Environmental pollution official method (Korea) Shimadzu UV-1601 UV-Visible Spectrophometer NH3-N(Ammonium Nitrogen) Phenate Method (Standard Methods) Shimadzu UV-1601 UV-Visible Spectrophometer NO3-N (Nitrate Nitrogen) Ultraviolet Spectrophotometric Screeing Method Shimadzu UV-1601 UV-Visible Spectrophomet Phosphorus PO4-P Ascorbic Acid Method Shimadzu UV-1601 UV-Visible Spectrophomet Temperature Fisher Scientific Accument 1003 Alkalinity Titration Method Suspended Solid Gravimetric method (Standard Methods) Drying Oven (Temp: 105 ℃)

As described above, the experiment was performed by distinguishing Reactor 1 with agitator and Reactor 2 without agitator, and the removal characteristics of COD, BOD, TN, TP, and SS by each reactor were as follows. same.

※ COD, BOD removal rate

The mean influent COD concentration during this experiment was 260 mg / L, and the mean influent concentrations for each of Samples 1-4 were 255 mg / L, 332 mg / L, 219 mg / L, and 235 mg / L. Except for sample 1, the effluent COD concentration was less than 20 mg / L. The average COD removal efficiency was 93.7% in Reactor 1, 92% in Reactor 2, and the COD removal efficiency was 1 ~ 2% higher. This is because the sludge is agitated even under anaerobic conditions, increasing the amount of contact between contaminants and microorganisms.

The COD removal efficiency in sample 1 was 87% in reactor 1 and 89% in reactor 2, which was lower than in other samples because both reactors were not stabilized yet. to be. In Sample 2, the COD removal efficiencies of Reactors 1 and 2 were 94% and 93%, respectively. The COD removal efficiency of Sample 3 was 93% in Reactor 1 and 90% in Reactor 2.

COD removal efficiencies in Sample 4, which reduced hydraulic retention time from 24 to 18 hours, were 94% and 91% in Reactors 1 and 2, respectively. This reason is believed to be due to the increase in the amount of microbial growth due to the increase in the reactor load.

It seems to be because the growth amount of a living thing increased.

Graph 1 (Change of inflow and outflow COD concentration)

Graph 2 (Processing Rate of COD by Operation Sample)

The average influent BOD concentration for this experiment was 134 mg / L, and the average influent concentrations for each of Samples 1-4 were 130 mg / L, 168 mg / L, 109 mg / L, and 130 mg / L. The effluent BOD concentrations in all samples except Sample 1 were below 10 mg / L in almost all cases (Graph 3). On the other hand, the ratio of BOD / COD of influent during the experiment period was 0.52.

Looking at graph 4 showing the BOD removal efficiency, in sample 1 reactor 1 is 91%, reactor 2 is 86%. BOD removal efficiency of reactors 1 and 2 in sample 2 was 94% and 93%, respectively.In sample 3 where the anaerobic (aerobic) reaction time was increased to increase denitrification efficiency, reactor 1 was 94% similar to sample 2. Reactor 2 is 94%.

Therefore, even if the aerobic reaction time of high microbial growth rate was reduced and the anaerobic reaction time of low microbial growth rate was increased, the BOD treatment efficiency was not affected. In Sample 4, in which only the hydraulic residence time was reduced under the conditions of Sample 3, BOD removal efficiencies of Reactors 1 and 2 were 93% and 92%, respectively.

Graph 3 (Change of Inflow and Outflow BOD Concentration)

Graph 4 (Processing Rate of BOD by Operation Sample)

※ Nitrogen removal rate

Operating conditions The nitrogen removal characteristics of each sample are shown in Graphs 5 and 9. The average concentrations of TN, NH ₃ -N and NO ₃ ^-- N in the influent during this experiment were 56.7 mg / L, 33.1 mg / L and 2.9 mg / L, respectively. / L, 2.2 mg / L, 13.3 mg / L, and reactor 2 was 19.7 mg / L, 2.5 mg / L, 14.4 mg / L, respectively. In the case of NO3--N, the effluent concentration is higher than the influent concentration because NH3-N is converted to NO3--N by nitrification.

NH ₃ -N removal efficiency of the sample from the two, as shown in the graph 8 is approximately 90%, it is almost all of the NH ₃ -N NO ₃ ^- means that the conversion to -N. As described earlier, since hydrogen ions (H ⁺ ) are generated in the nitrification process, the nitrification rate may be reduced due to the pH drop in the water. In order to maintain a proper pH in the reaction tank, 7.14 mg of alkalinity (as CaCO per 1 mg of NH ₃ -N) may be used. ₃ ) must be supplied. During the experimental period of the present invention, the average concentration of alkalinity in the influent sewage was 212 mg / L, which was about 10.1% short of the theoretical requirement, but the lack of alkalinity occurred when the NH ₃ -N concentration was much higher than the average value.

Graph 5 (Changes in inflow and outflow T-N concentrations)

Graph 6 (Processing Rate of T-N by Phase)

Graph 7, (Change in Concentration of NH ₃ -N by Phase)

Graph 8 (Processing Rate of NH ₃ -N by Phase)

Graph 9 (COD Treatment Rate by Phase)

However, the pH range of the effluent was shown to be 6.5-7.4, which is a good level for nitrification, so that the pH drop in the reaction tank was not large. This is because the increase in pH that occurs during the anoxic reaction has an effect of canceling the pH decrease seen in the nitrification reaction. In the anaerobic denitrification process (NO ₃ ^-- N → N ₂ ), in contrast to nitrification, the pH of the water rises because it consumes rather than releases hydrogen ions.

The removal efficiency of T-N is shown in Graph 6. The TN removal efficiency in sample 1 was 66% in reactor 1 and 56% in reactor 2, because the TN removal efficiency was lower than in other samples because both reactors were not stabilized yet. to be. In Sample 2, the T-N removal efficiencies of Reactors 1 and 2 were 70% and 64%, respectively.

In order to increase the denitrification time, which is an anoxic reaction, T-N removal efficiency of sample 3, which was reduced by 10 minutes and aeration time by 10 minutes, was 73% in reactor 1 and 67% in reactor 2 in one cycle.

These results show that it is necessary to adjust the aerobic or anaerobic reaction time according to the T-N inflow concentration. T-N removal efficiencies in Phase 4, which reduced hydraulic retention time from 24 to 18 hours, were 74% and 72% in Reactors 1 and 2, respectively. The reason why the T-N removal efficiency was high in Sample 4, which had a short hydraulic residence time, was because the concentration of DO in the reactor was lower than that of other samples during the aerobic reaction time.

In other words, the appropriate DO concentration required for aerobic reaction was about 1 to 2 mg / L, but the DO concentration in the reaction tank from sample 1 to 3 was 1.5 to 6.6 mg / L, which was much larger than that. DO concentrations were 1.5-2.1 mg / L, lower than those of the other samples. Therefore, when the DO concentration in the reactor is high when the aerobic reaction is converted into an anaerobic reaction, the conversion time becomes longer and the anoxic / anaerobic reaction time is reduced. There is a need to minimize it.

On the other hand, T-N removal efficiency was about 5% higher in Reactor 1 with agitator than in Reactor 2 without agitator, which is considered to be the result of the stirrer promoting the reaction during the anaerobic time.

※ Phosphorus removal rate

The phosphorus removal characteristics for each run sample are shown in Graph 10 and Graph 13. The mean concentrations of TP and PO4-P in the influent during the experimental period were 4.5 mg / L and 3.4 mg / L, respectively. In the case of effluent, reactor 1 was 1.6 mg / L and 1.2 mg / L, respectively. 1.8 mg / L and 1.3 mg / L, respectively.

The TP removal efficiencies in Phase 1 were 51% and 46% in Reactors 1 and 2, respectively. The reason for the lower TP removal efficiency than in other samples was that both reactors were not stabilized yet. This is because, as shown in Sample 1, the last reaction ended in anaerobic in one cycle. As described above, in the anaerobic state, phosphorus release by sludge may occur to increase the T-P concentration in the effluent.

Therefore, the TP removal efficiency of sample 2, which changed the operating conditions graph so that the last reaction in one cycle could end in aerobic state where phosphorus absorption by sludge occurred, showed 61% of reactor 1 and 56% of reactor 2. The removal efficiency of TP by) 2 is significantly higher than that of Sample 1. These results show that the last reaction in one cycle should end in aerobic state.

Graph 10 (T-P Concentration Change by Phase)

Graph 11 (Processing Rate of T-P by Operation Sample)

Graph 12 (Change of Concentration of PO ₄ -P by Phase)

Graph 13 (Removal Rate of PO ₄ -P by Phase)

In the case of Phase 3, which reduced the aerobic reaction time and increased the anaerobic reaction time in one cycle, the removal efficiencies of T-P by reactors 1 and 2 were 67% and 63%, respectively. In case of sample 4, which reduced hydraulic residence time from 24 hours to 18 hours, the treatment efficiency of T-P was 80% and 78%, respectively.

The increase in TP treatment efficiency may be caused by the increase of microbial proliferation due to the increase in reactor loading, but as described above, the anaerobic / oxygen-free reaction time of Phase 4 is greater than that of Phase 3 due to the reduction of DO concentration in the aerobic reaction time. .

On the other hand, the reason was high removal efficiency of TN and TP period standards above (Start-Up) is adsorption by the yellow soil pipe used as a filter medium to filter material layer above each reaction vessel is to occur at the initial stage NH ₃ ^+, NO ₃ ^- is because the ionic materials such as PO -3 ₄ was adsorbed to the yellow soil pipe. However, as the operation period passed, the adsorption effect by the ocher tube disappeared as the microorganisms adhered to the ocher tube surface.

※ SS removal rate

As shown in Graph 14, the average SS concentration of the influent during the experiment was 116 mg / L, and the average SS concentration of the effluent of each of Samples 1-4 was 11.4 mg / L, 6.6 mg / L, and 5.2 mg of Reactor 1, respectively. / L, 6.3 mg / L, Reactor 2 is 16.7 mg / L, 8.6 mg / L, 6.6 mg / L, 7.0 mg / L. Except for the start-up period, the effluent SS concentrations of the samples were below 10 mg / L in most cases.

In graph 15, the removal efficiency of SS can be seen to be removed more than 90% in all the (Phase). The lower removal efficiency in Sample 1 is due to the SS concentration of the effluent being similar to that of other samples, but due to the low SS concentration of the influent. The soil-coated continuous batch method of the present invention did not install a decanter as a effluent discharge device, but the average removal efficiency of SS from Samples 2 to 4 was 95% and 94% in each of Reactors 1 and 2, which was applied to other SBR methods. Compared with SS removal efficiency did not fall. This is because the SS was removed by the filtration of the media layer located above the reactor.

Graph 14 (Change inflow and outflow SS concentration)

Graph 15 (Processing Rate of SS for Each Operation Sample)

On the other hand, in general, when filling the filter medium in the reaction tank with the passage of time, the microorganisms are proliferating frequently clogging phenomenon occurs in the filter layer, the experimental apparatus of the present invention operated for more than 200 days, but this phenomenon did not appear. There are two reasons for the blockage of the media layer.

The first is because soil organisms such as earthworms in the upper soil layer use sludge as food, and the second is because sludge generated in the media layer falls into the SBR reactor, the lower space.

※ Concentration change by reaction time in one cycle

As shown in Graphs 1-4, the reaction of one cycle while operating the reactor with Samples 2 to 4 is performed by inflow (discharge) / anaerobic / aerobic / aerobic / aerobic / aerobic / sedimentation / aerobic / sedimentation. In order.

However, based on the quantity and concentration of influent and the quantity and concentration of water remaining in the reactor after discharge, the concentrations of these mixed waters at the inlet (discharge) time were calculated, and the concentration of the remaining time was measured directly.

The reason for not directly measuring the concentration of the mixed water for each water quality item is that the concentration of all parts in the reaction vessel could not be uniformed because the water in the reaction vessel was not stirred during the inflow and discharge at the same time.

※ COD concentration change with the reaction time

Changes in COD concentrations in Reactors 1 and 2 over time are shown in Graph 16 and Graph 17, respectively. COD concentration of influent was 374mg / L, 203mg / L, 244mg / L in sample 2, 3 and 4, respectively, and the mixed water COD concentration of Reactor 1 was 105mg / L, 61mg / L and 87mg / L, respectively. Is 71.9%, 69.9%, 64.4%.

Graph 16 (Changes in COD Concentration by Operation Cycle of Reactor 1)

Graph 17 (Change of COD Concentration by Operation Cycle of Reactor 2)

On the other hand, the mixed water COD concentration of Reactor 2 was 107 mg / L, 63 mg / L, 82 mg / L in Samples 2, 3, and 4, and the reduction rates due to dilution were 71.4%, 69.2%, and 66.4%. In the first anaerobic time, the COD removal rates of Reactor 1 were 91%, 78%, and 72% in Samples 2, 3, and 4, respectively, and in Reactor 2, 88.1%, 69.4%, and 72.4%, respectively.

Removal of the influent COD was almost complete at the first anaerobic and aerobic time zones, with the COD being slightly removed over time in the remaining time zones.

Although the first anaerobic reaction time of Sample 2 was 10 minutes shorter than Samples 3 or 4, the reason for the high COD treatment efficiency was presumably due to the relatively unusual amount of solids in the number of samples. This was determined by looking at the values measured after 60 minutes of elapsed time, as expected, with a higher residual COD of Sample 2 than Samples 3 or 4. COD analysis measured total COD, not dissolved COD.

※ Changes in nitrogen concentration with the passage of reaction time

Graphs 19 and 20 show changes in the concentration of NH ₃ -N in Reactors 1 and 2 as the reaction time elapsed. The NH ₃ -N concentrations of influent for each of Samples 2, 3 and 4 are 35.3 mg / L, 48.6 mg / L and 34.0 mg / L. At this time, the NH ₃ -N concentration of the mixed water in the reactor 1 is 9.2mg / L, 13.8mg / L, 11.8mg / L, respectively, in the case of reactor 2 13.6mg / L, 13.3mg / L, 11.7mg / L

Therefore, the reduction rate of NH ₃ -N concentration by dilution during the operation of Samples 2, 3, and 4 was 73.8%, 71.5%, and 65.2% in Reactor 1, respectively, and 61.5%, 72.6%, and 65.5% in Reactor 2, respectively. On the other hand, the NO3-N concentration change of Reactors 1 and 2 over time is shown in the graphs and graphs, respectively. NO3--N concentrations in the influent were 2.8 mg / L, 2.3 mg / L and 2.3 mg / L for Samples 2, 3 and 4, respectively. The mixed water NO3--N concentrations of Reactor 1 were 10.5 mg / L, 7.2 mg / L, and 5.8 mg / L, respectively, and the increase rates by dilution were 73.8%, 64.6%, and 60.0%, respectively. N concentrations were 7.7 mg / L, 7.0 mg / L, and 5.9 mg / L, and the increase rates due to dilution were 6.42%, 63.4%, and 60.6%.

Graph 18, (Change of NH ₃ -N Concentration by Operation Cycle of Reactor 1)

Graph 19 (Change in NH ₃ -N Concentration by Operation Cycle of Reactor 2)

Graph 20 (N0 ₃ ^-- N Concentration Change by Operation Cycle of Reactor 1)

Graph 21 (N0 ₃ ^-- N Concentration Change by Operation Cycle of Reactor 2)

As shown in the concentration gradients of NH ₃ -N and N0 ₃ ^-- N over time, sample 2, which had more aerobic time than anaerobic time, had a high nitrate rate in the early and mid-time periods, Under all operating conditions, nitrification of NH ₃ -N is almost complete.

However, when the dissolved TN removal amount of Graph 22 and Graph 23 showing the demassation was observed, the denitrification rates of Phases 3 and 4 where anaerobic time was greater than Phase 2 than the aerobic time were almost reached in the second half of the reaction time. It is similar to Sample 2, but the denitrification rate is higher in the early and mid-hours.

However, when the third anaerobic reaction was completed (230 minutes elapsed), the samples (Phase) 3 and 4 were almost completely denitrified at this point, but in the case of sample 2, the reaction time period Denitrification is nearing the end (Graph 22 and Graph 23). Therefore, in order to reduce the 6 hours set as one cycle in the present invention to increase the amount of water per day in terms of nitrogen removal, the anaerobic reaction time should be greater than the aerobic reaction time as in Samples 3 and 4.

Since sample 4 was operated for 18 hours, which was 6 hours shorter than the sample 3, the T-N load was higher than that of sample 3, but the residual amount of T-N was about the same. On the other hand, the reason why the dissolved TN concentration of the mixed water in the graph and the graph was lower than the concentration at the end of the first anaerobic reaction was that there was no elution of nitrogen component from the sludge because there was no agitation during the inflow (discharge) period, but the first anaerobic reaction time During the elution of the nitrogen component in the sludge, it is assumed that the concentration of TN is increased.

Graph 22, (T-N concentration change by operation cycle of reactor 1)

Graph 23, (Change of Dissolved T-N Concentration by Operation Cycle of Reactor 2)

※ Changes in phosphorus concentration over time

Changes in dissolved T-P concentrations in Reactors 1 and 2 over time are shown in Graph 24 and Graph 25, respectively. The influent TP concentrations were 5.5 mg / L, 4.9 mg / L and 3.5 mg / L in Samples 2, 3 and 4, respectively, and the mixed water TP concentrations in Reactor 1 were 2.6 mg / L, 1.8 mg / L and 1.5 mg / L. The reduction rate by dilution as L is 52.0%, 60.0%, 56.3%. On the other hand, the mixed water T-P concentration of Reactor 2 is 2.7 mg / L, 1.8 mg / L, 1.6 mg / L in Samples 2, 3, 4, the reduction rate by dilution is 51.5%, 59.0%, 55.5%.

The reason why the concentration of TP in the mixed water was lower than the concentration at the end of the first anaerobic reaction was that, as in the case of TN, the elution of nitrogenous components from the sludge did not occur during the inflow (discharge) period, but during the first anaerobic reaction, It seems to have occurred. As shown in (Figure 24 and Figure 25), the removal of T-P rarely occurs at the beginning of the reaction time, but has been increasing since the middle.

This phenomenon is due to the PO₄The change in concentration of -P is almost identical (graph 26 and graph 27). The reason for this is that the repetition time of anaerobic / aerobic reaction is shorter than the early part after the middle part.

Therefore, it is necessary to keep the anaerobic / aerobic repetition time as short as possible within a given reaction time in order to increase the amount of phosphorus removed during operation of the reactor. On the other hand, the amount of phosphorus removal of sample 4, which has a shorter hydraulic residence time than sample 3, is higher because the inflow load increased, and thus the amount of phosphorus consumption increased.

This suggests that rather than lengthening the hydraulic residence time in treating the same amount of influent, it is possible to increase the removal of phosphorus by increasing the growth of microorganisms within a unit time.

Graph 24 (Change of Dissolved T-P Concentration by Operation Cycle of Reactor 1)

Graph 25 (Change of Dissolved T-P Concentration by Operation Cycle of Reactor 2)

Graph 26 (PO ₄ -P Concentration Change by Operation Cycle of Reactor 1)

Graph 27 (Change of PO ₄ -P Concentration by Operation Cycle of Reactor 2)

In addition, the PLC (20, Programmable Logic Controller, hereinafter referred to as PLC) was mounted as shown in FIGS. 1, 3, and 4 for the automatic operation of the SBR reactor, and real-time image monitoring and operation status through a remote monitoring system. The configuration is as follows.

In the present invention, a more efficient PLC was installed and used than a timer to automatically adjust the reaction time of the SBR reactor.

PLC is a highly autonomous control device that replaces the functions such as relay timer and counter in the control panel, which are used in the past, with semiconductor elements such as ICs and transistors, and adds numerical operations to basic sequence control functions to enable program control.

The field of application of PLC is being expanded by the demand for automation and high efficiency of equipment. In the past, over the medium-sized relay control panel replacement effect, the current trend of high performance and high speed can be widely applied from small scale machine to large system equipment.

PLC is composed of a microprocessor and a memory centered around a central processing unit (CPU) that acts as a human brain, an input / output unit that connects signals to external devices, and each part. It is composed of a power supply unit for supplying power to a peripheral device and a peripheral device for writing a program to a memory in the PLC.

The PLC used for the automated operation of the reactor in the present invention is Master-K10S. The reason for using this is because the maximum number of contacts is 24 points and it is suitable for small use. Another feature of this PLC is the application of EEPROM, which eliminates the need for a battery for long-term storage of user programs, and enables wide communication control with support for RS-232C / RS-485 communication. Schedule program is available with clock function (Option).

And PLC program of Master-K10S uses ladder program. According to the method of writing this program, the operation condition by reaction time is matched, and PLC's data memory is classified into various types according to the intended use.

The first is an input / output relay that is directly connected to an external device. Since input state is saved in memory inside PLC, a, b contact is available, and only a contact is available for output contact. Use the symbol P as the identifier.

The second is an auxiliary release. This is PLC's internal relay, so it is impossible to output directly to the outside, but when connected to I / O relay, external output is possible. It is used to convey information when processing internal information during program operation.

The third is the keep relay. The auxiliary relay has the same usage purpose, but the a and b contacts can be used as an area to preserve the previous data when the RUN is started by turning on the power, and is distinguished from other relays by attaching K as an identifier.

The fourth is a special relay, which is an internal contact that provides the dynamic state or pulse of PLC. When PLC is in (RUN) state or (PROGRAM) state, it turns on a specific contact point or generates pulses that are ON / OFF at intervals of 0.1 seconds, 1 second, 1 minute, etc. during operation.

Here, the PLC will be briefly described. As shown in FIGS. 3 and 4, information is detected by an input device 21 including a limit switch, a proximity switch, and a photoelectric switch (hereinafter referred to as a sensor), and the detected signal is a microprocessor. The microprocessor 25 stores the information in the memory 26 and operates the output unit 24 including the electronic switch, the solenoid and the lamp according to the information.

Each of the components transmitted to the output unit 24, that is, the electromagnetic switch and the solenoid, opens and closes a valve to introduce air into the SBR reactor through the blower to control the amount and time of the aeration. In various variations, this controls the locking and closing through a timer to control the amount of air inlet or shut off. Here, in addition to the components of the output unit may be replaced with equivalents having the same similar function.

Through the PLC it is possible to remotely control the reactor and to monitor the state of the reactor. In other words, Such a system may be particularly useful for small wastewater treatment plants, such as village-level sewage treatment plants, which do not have on-site personnel or do not require management at all times.

The real-time monitoring system configuration of the field experiment device is installed in the SBR reactor, pH, DO, water temperature automatic measuring device, the field host (Host) with such automatic measuring device and the server and client (receiving, storing and managing each information) A real-time field tester monitoring system was constructed for each location where) is located.

In the first step, the information of the field host is generated and sent to the server at 9 second intervals, and the server is stored at the database based on the 9 second intervals for transmission.

In the second step, considering that the network between the site host and the server is temporarily or long suspended, the site host only stores data when the server is disconnected, and only the server when connected. .

In addition, the client where the third administrator is located has established a system that transmits the information after confirming the identity of the visitor when requesting data transmission. As shown in FIG. 4, the computer 30 displays the information coming from the input devices, that is, sensors, installed in the PLC 20 and the reactor 10 through the soil layer. Administrators can report this and monitor or control the status. Of course, it is also connected to the Internet and can be observed on the Internet.

The present invention is not limited to the above-described embodiment and can be applied to those who are engaged in the industry within the scope of the claims without departing from the scope of the claims.

As described above, the soil-coated continuous batch sewage treatment method;

First, the processing efficiency of nitrogen and phosphorus is improved, without burdening the appeal and coastal waters,

Secondly, deodorization facilities to remove odors are unnecessary,

Third, because it does not cause secondary pollution by pathogens caused by scattering, etc., it is possible to install facilities in residential areas of large cities.

Fourth, there is no need to separately install suspended solids countermeasure and decanter (treated water discharge device) by sludge bulking,

Fifth, since microorganisms are naturally supplied from the coated soil, artificial supply is not necessary due to the death of microorganisms, so that the processing function is stable.

Sixth, it can be used as a landscaping facility with vegetation on top of the covered soil.

Seventh, equipped with a PLC for automatic operation in the reaction tank can always know the operating state without the operator,

Eighth, the maintenance cost is low because the above-mentioned effect is easy to maintain and do not need microorganism supply,

Ninth, there is no need for separate facilities such as odor removal, bulking prevention, decanter, and landscaping, which greatly reduces the cost of facilities.

Therefore, according to the present invention, it is considered that it is possible to contribute to the change of residents' awareness about the sewage treatment facility, which is composed of environmentally friendly and ecological facilities and avoids hate facilities.

In addition, in terms of economics, compared to the previously developed SBR method, additional facilities according to the mechanical facilities and processing functions are greatly reduced, which is advantageous in terms of maintenance and energy saving.

Claims (1)

In the sewage treatment method, provided with a predetermined space portion inside the continuous batch reactor 10 having an inlet and discharge outlet for waste water inlet, and install the filter media layer 12 so as to be spaced apart from the bottom by a predetermined space, After the capillary network 13 is fixed to the upper part of the filter medium layer 12, the soil layer is coated on the upper part of the capillary network 13, and plants such as grass are planted thereon so that the microorganisms of the soil are naturally supplied into the reactor. and, DO, pH, temperature measurement to automatically measure the DO, pH temperature in the reaction tank 10 to control the aerobic and / or aerobic reaction to proceed by aeration and agitation through the aeration pipe inside the reactor (10) For example, the sensor 15 may be installed and the signal detected by the sensor may be transmitted to the PLC 20 to be stored in the computer 30 so as to be monitored and controlled at a long distance through the computer 30. A soil-coated continuous batch sewage treatment method characterized by purifying wastewater by controlling the aeration amount, aeration time and stirring time through an output unit such as an electronic switch or solenoid by controlling the PLC (20).