KR100948494B1 - A method for pretreatment of waste sludge - Google Patents

Abstract

The present invention relates to a sewage sludge pretreatment method, wherein the synergistic effect of hydraulic cavitation and ozone is improved by injecting ozone generated from the ozone generator into the sludge at the front end or the rear end of the apparatus for generating the hydraulic cavitation. Sewage sludge pretreatment method and method for comprehensively performing sludge reduction, improving sludge dewatering capacity, improving anaerobic digestion efficiency, etc. by raising and destroying sludge structure and destroying cell membranes. It relates to a sewage sludge pretreatment apparatus using. The sewage sludge pretreatment apparatus is circular, elliptical, having a small cross-sectional area by a pipe (with a motor) capable of transporting sludge at high pressure and high speed, and a pipe having an ozone injection unit optimizedly disposed at an appropriate interval with the ozone generator. Or through a polygonal orifice to create a hydraulic cavitation phenomenon.

Sewage Sludge Pretreatment, Cavitation, Ozone

Description

A method for pretreatment of waste sludge}

The present invention relates to a sewage sludge pretreatment apparatus and a method for pretreating sewage sludge using the same.

Waste sludge or excessive sludge, which is continuously generated in biological treatment tanks of sewage and wastewater treatment plants, is one of the representative organic wastes. To date, these organic waste sludges have been treated in many ways, including landfilling, incineration, dumping, composting, auxiliary fueling, and carbonization, but most sewage and wastewater treatment plants have adopted the most cost-effective treatment. For this reason, a large amount of organic waste sludge has been dumped or landfilled around the world. In Korea, more than 70% of sewage sludge has been disposed of by dumping at the end of 2006, since direct landfilling of organic waste sludge was banned in 2003. However, with the joining of the London Convention, an international environmental convention, such sea dumping will be banned in Korea after January 1, 2012. Therefore, in the future, this organic waste sludge will have to be treated in an appropriate way on land. Against this background, the future solution is to reduce sludge generation by itself, to recycle it as compost or cover material or auxiliary fuel, and to recover energy sources such as methane (CH ₄ ) through anaerobic digestion. Emerging into the room. Therefore, the methods for properly pretreating waste sludge to implement these methods have attracted great attention in the related industry in recent years. However, many technologies are still insufficient in terms of efficiency and cost.

In order to properly pretreat the sludge, it is important to first understand the structure of the sludge floc. Sludge flocs are lumps of microorganisms frozen together and are connected to each other as shown in FIG. 1 through extracellular polymeric substances (EPS).

In order to reduce sludge fundamentally, these sludge floc structures must be broken and the cell walls must be broken to allow the release of microbial components. The sludge treated in this way is returned to the biological treatment tank or used as a carbon source of the advanced treatment process to remove nitrogen or phosphorus, so that the waste sludge discharged from the sewage treatment plant can be zeroed. In addition, in order to be recycled by composting, the water content must be lowered to less than 60% after dehydration. In this case, the pore water and some internal water of the cells around the sludge should be removed. There is a limit that only free water can be removed only by the commonly used mechanical dehydration method. Therefore, other alternatives are needed, and suitable alternatives must be techniques that can destroy these sludge floc structures and break cell walls. In the case of sludge treatment through anaerobic digestion, when the anaerobic digestion efficiency is increased, the solids are converted into biogas, which can recover a large amount of energy source, and consequently, the amount of sludge to be disposed of eventually decreases. You get an effect. Therefore, a pretreatment technique is required to increase the extinguishing efficiency. For this purpose, the amount of organic matter present as a solid and the amount of dissolved organic matter must be increased. This is possible only by breaking the sludge floc structure as described in the above two methods and at the same time destroying the microbial cell wall to release the intracellular material to the outside.

So far, sludge pretreatment methods have been tested and developed such as ultrasonication, high temperature heat treatment, ozone oxidation, cavitation treatment, alkali treatment, enzyme treatment, mechanical treatment, acid treatment, microbial treatment, wet oxidation process and vacuum treatment. Kyu-Cheol, cited in 2008 KOSEN Expert Review).

Ozone oxidation of sewage sludge destroys the cell walls of the sludge reacted with ozone, releasing substances inside the cells (COD components). In addition, polysaccharides, proteins, lipids, and the like react with ozone to be converted to low molecular weight compounds. If the ozone dose is high enough, intracellular substances can be converted to carbon dioxide and water and mineralized. Sludge treatment using ozone can be divided into treatment for sludge reduction and pretreatment of anaerobic digestion. In the sludge reduction treatment, it was reported that an ozone injection of 0.05 kgO ₃ / kgTSS resulted in a sludge reduction effect of 19-35%. When applied to anaerobic digestion pretreatment, digestive sludge reduction of about 10% was obtained. The ozone dose was increased from 0.03 kgO ₃ / kgTSS to 0.06 kgO ₃ / kgTSS, resulting in an increase in soluble COD emissions from 11% to 16%. However, it has been reported that after the anaerobic digester, the COD of the effluent is increased and the cost is higher than the sludge reduction amount. In one study, the payback period for ozone pretreatment was estimated to be about six years. On the other hand, as a solution to this problem, it was reported that the closed-loop ozonation unit in the medium temperature digester after ozone pretreatment was able to obtain much better gas production and COD reduction than the ozone injection amount (Nam Gung Kyu, 2008 KOSEN Expert Review) Requoted from).

Hydrodynamic cavitation ( HC ) differs in ultrasonic cavitation and principle, but shows similar characteristics in effect. HC is produced through turbulent flow of liquids, and often occurs when there is a large pressure difference in the flow of liquids. For example, if the device is made to pass through an orifice with a small cross-sectional area while moving the fluid at high pressure in a pipe with a constant cross-sectional area, there is a large pressure difference at the discharge portion of the orifice, which causes cavitation immediately after the discharge portion. This happens. Another example is a device that allows a fluid passing through an orifice to meet a blade. The orifice shape is not spherical but excellent in elliptical shape. In this case, as the blade vibrates, the cavitation can be made very clear and effective. On the other hand, unlike the cavitation through one orifice, passing the fluid through a plurality of orifices can increase the cavitation effect. Variables affecting HC include the timing of cavitation, together with pressure, flow rate, and cavitation chamber design. The pressure at the orifice inlet, the restoring pressure at the orifice outlet, and the minimum pressure for cavitation are important, and clarification of the time factors is essential for commercial applications (Arrojo and Benito, "A theoretical study of hydrodynamic cavitation ", Ultrasonics Sonochemistry, doi: 10.1016 / j.ultsonch. 2007.03.007 2007) (Re-quoted by Nam Gung-Kyu Chul, Journal of the Korean Society of Civil Engineers, Vol. 55, pp. 50-55, (2007)).

One study reported that the residence time of cavitation pretreated sludge could be drastically reduced from 13 days to 6 days when not treated at moderate anaerobic digestion. In addition, treatment efficiency has been reported to be considerably improved by adding alkali treatment prior to cavitation treatment in terms of sludge reduction effect and gas production. This process has been commercialized under the name MicroSludge ^™ (Canada) and has recently been applied to real scale plants. In this process, the concentrated sludge is alkali treated with a rotary drum concentrator at pH 8.5-10 for about 1 hour, followed by cavitation at high pressure of 12,000 psi. As a result, up to 80% of sludge solubilization was possible. At this time, the pH of the solubilized sludge changes to 6.8-7.4. It has been reported that mesophilic digestion of this treated sludge can reduce volatile solids by 18-78%. Another example of a commercially available cavitation process is the Biogest Crown Disintegration System (UK). This process uses very fast flow rates and performs three cavitation treatments before sludge is introduced into the anaerobic digester. Another example of a commercialization process is Rapid Non-equilibrium Decompression (RND). This process takes advantage of the phenomenon that CO ₂ dissolved due to supersaturation under high pressure rapidly expands with the pressure drop, thereby destroying the cell wall. The advantage of this process is that CO ₂ can be reused and energy costs are low, resulting in a payback period of less than two years.

The present inventors inject the ozone generated from the ozone generator into the sludge at the front end or the rear end of the device which causes the hydraulic cavitation, thereby inducing the synergy effect of the hydrodynamic cavitation and ozone, and thus the sludge structure. And the cell wall (membrane), so as to solubilize the sludge as a result of reducing the sludge, improved sludge dewatering capacity, anaerobic digestion efficiency can be achieved in one process. The invention was completed.

In order to increase the overall efficiency of the sewage sludge treatment, as described in the background, a process that effectively dismantles the structure of the sludge floc and attacks and destroys the cell walls of the microorganisms to release the intracellular material and the internal water to the outside; and A device is needed. Cavitation and ozonation technologies provide an effective means of achieving this goal and, when used together, provide excellent synergy. Therefore, by effectively integrating these technologies to pre-treat waste sludge, it is to provide a process and apparatus that can totally reduce sludge, improve sludge dewatering efficiency, and improve digestion efficiency.

According to a first aspect of the present invention, there is provided a method of pretreating sewage sludge, comprising: treating sewage sludge with ozone generated from an ozone generator; And it provides a sewage sludge pretreatment method comprising the step of passing the ozone treated sewage sludge having an orifice having a cross-sectional area smaller than the inlet at a high pressure of 2000 ~ 8000 psi. When the pressure applied to the sewage sludge is less than 2000 psi, it is difficult to obtain a hydrodynamic cavitation effect to dismantle the sludge floc structure and destroy microorganisms or cells, and when the pressure is higher than 8000 psi, The structure has to be high pressure resistance, and requires a lot of energy in terms of operation of the device, and the economy is inferior.

As a second aspect of the present invention, there is provided a method of pretreatment of sewage sludge, comprising: passing an orifice having a cross-sectional area smaller than the inlet at a high pressure of 2000-8000 psi; And it provides a sewage sludge pretreatment method comprising the step of treating the passed sewage sludge with ozone generated from the ozone generator.

As a third aspect of the present invention, the present invention provides a method of pretreatment of sewage sludge, wherein the sewage sludge is passed through an orifice having a cross-sectional area smaller than the inlet at a high pressure of 2000 to 8000 psi, between the high pressure generating portion and the orifice. The present invention provides a sewage sludge pretreatment method, wherein the sewage sludge is treated by injecting ozone generated by an ozone generator, and the ozone treated sewage sludge passes through the orifice and is further treated by a hydraulic cavitation phenomenon. As another embodiment of the present invention, an effective amount of hydrogen peroxide (H ₂ O ₂ ) in addition to the ozone supply; Sodium hydroxide (NaOH); Or it can be supplied with the hydrogen peroxide (H ₂ O ₂₎ and sodium hydroxide (NaOH).

As a fourth aspect of the present invention, the present invention provides a sewage sludge pre-treatment apparatus as shown in Fig. The sewage sludge pretreatment device is a high pressure pump (2) for supplying a high pressure of 2000 to 8000 psi to the pipe (3), a concentration tank (1) in which activated sludge is concentrated, the pipe (3), discharged from the high pressure pump The sewage sludge is passed through the high pressure state and is connected between the pipe (3) having an orifice having a cross-sectional area smaller than the inlet at the end, a storage tank (5) for collecting the sewage sludge passing through the pipe, and from the concentration tank to It characterized in that it comprises an ozone generator (4) for supplying ozone to sewage sludge.

According to an embodiment of the present invention, ozone generated by the ozone generator may be supplied between the concentrating tank 1 and the tube 3, and between the inlet and the orifice portion of the tube 3. It may be supplied, or may be supplied between the tube (3) and the reservoir (5). The present invention may be any one type of tube selected from the group consisting of a tube having a circular, oval or polygonal shape according to an embodiment.

As a fifth aspect of the present invention, the present invention provides a sewage sludge treatment method using the sewage sludge pretreatment method.

As a sixth aspect of the present invention, the present invention provides a sewage sludge treatment apparatus including the sewage sludge pretreatment apparatus.

When the sludge was treated using the apparatus according to the present invention, it was confirmed that the improved effect than the case of only cavitation treatment or only ozone treatment. Ozone oxidation of sludge treated only once with cavitation to obtain the best results in a short time period adequately accounts for the synergistic effect of the cavitation and ozone oxidation processes presented in the present invention. Therefore, the sewage sludge pretreatment apparatus and method according to the present invention have the effect of reducing sludge, improving sludge dewatering efficiency and improving anaerobic digestion efficiency.

Hereinafter, the present invention will be described in detail with reference to the drawings. However, this description is not intended to limit the scope of the present invention. The scope of the present invention is defined by the claims, and can be easily replaced by those skilled in the art based on the description of the present invention and the claims. Crazy

Example  1.Activity according to the present invention Sludge  Pretreatment unit

2 shows a schematic view of an activated sludge pretreatment apparatus according to the present invention. The surplus sludge (1) generated in the biological treatment process (typically activated sludge process) is concentrated in a concentration tank, and then conveyed at a high speed through a high pressure pump (2) to produce an orifice with a small cross-sectional area. The ozone generated by the ozone generator 4 is injected in conjunction with this process. The treated sludge is returned to the bioreactor 6 or transferred to the dehydration device 7 through a process that is appropriately treated as necessary in the storage tank 5. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 3 to 5. However, the original characters such as 1 to 7 are not intended to indicate the structure of the present invention but are intended to indicate the processing sequence shown in each embodiment.

Example  2. Cavitation  Ozone treatment Sewage sludge  Impact

  (1) Experimental Materials and Methods

1) The sewage sludge used in this experiment was sampled from a biofilm reactor (MBR) pilot facility (treatment capacity: 300 tons / day, average MLSS: 8000 mg / L) installed in the sewage treatment plant. Samples used for each experiment were taken at 0 minutes (raw water), 1 minute, 5 minutes, and 10 minutes, respectively, with cavitation treatment, ozone treatment, and ozone treatment after one cavitation treatment.

2) Analysis method

① pH-Each sample was measured for pH using a pH meter.

② Temperature-Each sample was measured for temperature using a thermometer.

③ Suspended solids (SS; suspended solids)-Wash the glass fiber filter (GF / C) with purified water in advance, place it on a watch plate and dry it for 2 hours in a dryer at 105-110 degrees. Was weighed precisely and attached to the filter. Aspirate the sample with a suitable amount and filter it, and then wash the filter wall and filter residue with water several times, take out the glass fiber with a pincent, take it out of the filter and place it on a watch plate and dry it in a dryer at 105-110 degrees for 2 hours. The mixture was allowed to cool in a sulfuric acid desiccator, and weighed precisely as a constant weight. The difference in the weight of the glass fiber filter before and after filtration was calculated to be the amount of suspended solids.

④ SCODcr-After filtering the sample with glass fiber filter (GF / C), the filtered solution is injected into 2ml of water CODcr analysis kit and reacted at 150 ℃, and then SCODcr is analyzed using HS-2300Plus water analyzer (Humas, Korea). Analyzed.

3) Experiment apparatus

Sludge treatment experiment using only cavitation, the sludge introduced in the sludge storage tank (see 5 in Fig. 2), such as '①' shown in Figure 3 was to have a constant residence time. As shown in FIG. 2, the sludge of the reservoir (see 5 in FIG. 2) is a cavitation device composed of a rectangular box longitudinally bonded to the tube 3 interposed between the high pressure pump 2 and the reservoir 5. The treated sludge was treated at the sampling port as shown in ④ in FIG. 3, and the treated sludge was transported through the tube as shown in ⑤ in FIG. 3.

In the sludge treatment experiment using only ozone (Fig. 4), sludge introduced in the sludge storage tank (see Fig. 2 in Fig. 2) as shown in Fig. 4 has a constant residence time. The sludge of the reservoir (refer to 5 in FIG. 2) was treated by contacting the sludge with ozone generated in the ozone generator (see 4 in FIG. 2) through the gas-liquid mixing pump shown in FIG. The sludge treated in contact with ozone was sampled at the sampling port as shown in ⑤ shown in FIG. 4, and the treated sludge as shown in ⑥ shown in FIG. 4 was transferred through the tube.

Sludge treatment experiment using a combination of cavitation and ozone (Fig. 5) is the sludge introduced as shown in ① shown in Fig. 5 as shown in ② of Fig. In FIG. 2, 5), the sludge has a constant residence time. The sludge of the reservoir (refer to 5 in FIG. 2) was subjected to the sludge secondary by contacting the sludge with ozone generated in the ozone generator (see 4 in FIG. 2) through the gas-liquid mixing pump shown in ④ of FIG. . The sludge treated secondly in contact with ozone was sampled at the sampling port as shown in ⑥ shown in FIG. 5, and the treated sludge as ⑦ shown in FIG. 5 was transferred through the tube.

 (2) Effect of Cavitation Treatment on Sewage Sludge

The cavitation device was manufactured by itself (see FIG. 3), and the characteristics of the sludge were tested by changing the pressure of the cavitation and the cavitation contact time according to the change of the orifice size and the motor frequency. 20L of sludge samples were tested at a cavitation pressure of 200 bar (Oripisk machine D1.5mm).

enemy 1 minute 2 minutes 5 minutes 10 minutes Sludge Contact Count (times) - 0.8 1.6 4 8 pH 7.14 7.12 7.11 7.03 6.91 Temperature (℃) 26 32 36 44 55 SCODcr (mg / L) 45.2 262.49 325.76 532.29 1070.81 SCODcr / SS Ratio (× 1000) 5.02 29.17 40.72 66.54 133.85

   -Processing time

     When the sludge from the storage tank is circulated to the cavitation, the sludge passes through the cavitation device about 0.8 times a minute. Therefore, after 10 minutes of processing, the number of passes through the cavitation device is about eight times.

   Temperature change

     When processed through cavitation, a rapid pressure change occurs from high pressure to low pressure as it passes through the cavitation device, at which time a strong shear force is applied, a shock wave is generated, and a cavitation phenomena is generated, which generates considerable heat. Will be. The generation of heat causes the sludge temperature to rise as it passes through the cavitation apparatus.

   pH change

     When treated with cavitation alone, the pH change is mainly due to the elution of internal substances due to the destruction of microorganisms. As a rule, they do not deviate significantly around neutral and the experimental results show this well.

   -SCODcr

     Soluble COD changes significantly before and after cavitation. This is because the soluble COD component is greatly increased due to the elution of the intracellular material due to the destruction of the microbial floc structure and the collapse of the cell wall.

   -SCODcr / SS

     Reduction of SS occurs with an increase in soluble COD due to microbial flocs and cell destruction. As a result, the SCOD / SS ratio is the most important variable in indicating the degree of microbial floc and cell destruction. The decrease in SS is small compared to the increase in SCOD, because in the case of cavitation, the reaction of converting a large molecular weight material into a small molecular weight rarely occurs within a short time of 10 minutes. In general, the rate of increase of SCOD varies much like the change of rate of increase of SCOD / SS.

  (3) Effect of ozone treatment on sewage sludge

The ozone generating device is a water-cooled device (SW-50 of Sewang C-Tech Co., Ltd.), and the ozone generating capacity is up to 50g-O3 / hr. The raw material oxygen was pure oxygen (99.99%) stored in a high pressure vessel. The ozone treatment experiment was conducted by contacting the sludge and ozone with 20 l sludge in a reaction tank of D30cm, H1000cm (see Fig. 4). The ozone generated by the ozone generator was contacted with the sludge and ozone by using a gas-liquid mixing pump (Vacuum Hog Pump SP-VF1 of Sin-pung acid pump). A stirrer was installed at the upper end to remove bubbles generated in the reactor.

Gas-liquid Mixing Pump Capacity: 1HP (0.75Kw), 60Hz

Gas-liquid Mixing Pump Flow Rate: 20L / min

Sample volume: 20L

① Ozone Concentration: 30g / hr

enemy 1 minute 5 minutes 10 minutes Ozone Sludge Contact Count (times) - One 5 10 pH 7.14 6.63 6.46 6.19 Temperature (℃) 26 27 30 33 SCODcr (mg / L) 37.69 107.91 350.97 557.96 SCOD / SS Ratio (× 1000) 5.38 15.42 87.74 139.49

② Ozone Concentration: 50g / hr

enemy 1 minute 5 minutes 10 minutes Ozone Sludge Contact Count (times) - One 5 10 pH 7.14 6.44 6.19 5.75 Temperature (℃) 26 28 30 35 SCODcr (mg / L) 37.69 278.49 616.89 907.46 SCOD / SS Ratio (× 1000) 5.38 46.42 154.22 302.49

   -Processing time

     The sludge was circulated with the gas-liquid mixing pump and the sludge passed through the gas-liquid mixing pump once a minute. Eventually, as the number of passes increases, ozone input increases and ozone oxidation of sludge increases.

   Temperature change

     When oxidizing the sludge liquid by ozone, a slight temperature rise occurs while passing through the gas-liquid mixing pump, and the temperature rise is caused by some exothermic reaction. However, compared to cavitation treatment, the temperature rise is slight and the experimental results are well shown.

   pH change

     Unlike cavitation treatment, ozone oxidation causes a relatively large pH change due to ozone sludge and substances in the liquid phase and the reactor. As ozone is introduced, the pH shifts towards acidity and changes significantly with ozone dose and treatment time. The experimental results show this well. In particular, when comparing the ozone dose 30g / hr results and 50g / hr results it can be seen that the pH decrease becomes more significant as the ozone dose increases.

   -SCODcr

     In the case of ozonation, unlike cavitation, the increase in SCOD is expected to be slightly slower than cavitation because ozone reacts directly with sludge solids and substances in the liquid phase to destroy sludge. As the ozone dose increases, the SCOD growth rate is expected to increase, and a significant increase in SCOD can be observed when the ozone dose increases (30g / hr-> 50g / hr).

   -SCODcr / SS

     In the case of ozonation, unlike cavitation, ozone reacts directly and converts a large molecular weight material into a small molecular weight material, which is accompanied by a change in SS. As a result, the SCOD growth rate and the SCOD / SS change rate are different. Experimental results show this well.

   -Effect of ozone input

     Increasing the input ozone amount from 30 g / hr to 50 g / hr increases sludge breakdown, as is generally expected, resulting in an increase in SCOD and an increase in SCOD / SS. Experimental results show this well.

  (4) Effect of Cavitation and Ozone Treatment on Sewage Sludge

Cavitation Pressure: 200bar (Orispisk D1.5mm)

Cavitation processing count: 1 time

Gas-liquid Mixing Pump Capacity: 1HP (0.75Kw), 60Hz

Gas-liquid Mixing Pump Flow Rate: 20L / min

Sample volume: 20L

① Ozone Concentration: 30g / hr

enemy 1 minute 5 minutes 10 minutes Ozone Sludge Contact Count (times) - One 5 10 pH 7.14 6.53 6.32 6.18 Temperature (℃) 26 30 32 35 SCODcr (mg / L) 37.69 404.28 719.74 1065.90 SCOD / SS Ratio (× 1000) 5.38 67.38 179.94 355.30

② Ozone Concentration: 50g / hr

enemy 1 minute 5 minutes 10 minutes Ozone Sludge Contact Count (times) - One 5 10 pH 7.14 6.42 6.17 5.76 Temperature (℃) 26 28 32 35 SCODcr (mg / L) 37.69 549.99 924.69 1242.10 SCOD / SS Ratio (× 1000) 5.38 78.57 231.17 414.03

   -Processing time

     After one treatment with cavitation, ozone oxidation treatment was performed. Therefore, processing time of about 1 minute and 15 seconds is given. Since then, the experiment was carried out with different ozone inputs, and the total treatment time was 1 minute and 15 seconds to the ozone treatment time.

   Temperature change

     The temperature change is not large because only one cavitation treatment is performed, and the increase tends to be similar to that of only ozone treatment.

   pH change

     It can be seen that the pH change is significantly decreased due to the effect of ozone treatment compared with the cavitation treatment alone. The effect of one cavitation treatment was found to be slightly lower than the treatment with ozone alone. In particular, when the ozone input amount is small (30 g / hr) is stronger and the ozone treatment time is longer, there is no big difference, but the difference can be seen at the initial ozone treatment.

   -SCODcr

     In ozone treatment after cavitation, the SCODcr rises very rapidly. The rate of increase is very high compared to cavitation only. In addition, the rate of increase of SCODcr is much higher than in the case of treatment with ozone alone. In the case of ozone treatment at 30 g / hr, the SCOD increased to about 350 after 5 minutes. However, when ozone was injected for 5 minutes after one treatment by cavitation, the SCOD rose to about 720 and increased by more than 100%. In addition, the SCOD increased to about 910 after 10 minutes of treatment at 50 g / hr of ozone injection, and the SCOD value increased to about 925 after 5 minutes of cavitation treatment.

   -SCODcr / SS

     As described above, when cavitation treatment alone, SS decreases relatively, so that the SCOD / SS ratio is smaller than that of ozone oxidation. However, when combined with cavitation and ozone oxidation, excellent synergy can be obtained. In the case of 30 g / hr of ozone dose, the SCOD / SS value was 355 for 10 minutes ozone treatment after one cavitation treatment, and 139 for 10 minutes treatment with ozone alone. As a result, the SCOD / SS value increased by more than 150%, which is much higher than the 91% increase rate of the SCOD value. From this, it can be seen that ozone oxidation effectively caused SCOD increase and SS decrease following destruction of the floc structure by cavitation. As the ozone dose increased to 50 g / hr, the SCOD increase was 37% and the SCOD / SS increase was 37%, which is understood as the effect of ozone oxidation was relatively increased.

   Synergy

     As described above, when ozone injection was performed for 5 minutes after one cavitation treatment, the total treatment reaction time was about 6 minutes and 15 seconds. The increase of SCODcr by this treatment is more than 30% at 30g / hr ozone dose and about 2% at 50g / hr ozone dose, compared to 10 minutes treatment with ozone alone. It can be seen that even a reaction time of about 60% yielded better treatment results. As a result, it can be seen that the combination of cavitation and ozone effectively worked on the SCOD rise.

     This synergy effect is expected to be efficiently obtained through the proper combination of cavitation treatment and ozone treatment. For example, as shown in the previous experimental results, after one cavitation treatment and 10 minutes of treatment with an ozone dose of 30 g / hr, the SCOD increase and SCOD / SS increase could be obtained. The following table shows the SCOD increase per unit ozone dose.

division SCOD (mg / L) Increase / ozone dose (g) 30g / hr ozone treatment 104 One Cavitation + 30g / hr Ozone Treatment 206 50g / hr Ozone Treatment 104 One Cavitation + 50g / hr Ozone Treatment 145

     As can be seen from this result, the best SCOD increase compared to the unit ozone dose is the case of 30g / hr ozone treatment after one cavitation. As a result, it can be seen that there is a combination that obtains the highest efficiency compared to the input energy.

The sewage sludge pretreatment apparatus and sewage sludge pretreatment method using the same according to the present invention can reduce sludge, improve sludge dewatering efficiency, and improve anaerobic digestion efficiency. By combining synergy with physical treatment and chemical treatment, it can be used more efficiently than existing methods in sewage sludge treatment.

1 The structure of the sludge flocs and the type of surrounding water are shown.

2 shows a schematic view of an activated sludge pretreatment apparatus according to the present invention. The waste sludge (1) generated in the biological treatment process (typically activated sludge process) is concentrated in a concentration tank and then conveyed at a high speed through a high pressure pump (2) so that the end portion has an orifice of small cross-sectional area (3). It is discharged through, and in connection with this process, ozone generated in the ozone generator 4 is injected. The sludge treated in this way is transferred (6) to a bioreactor (6) or to a dehydrator or anaerobic (or aerobic) digester through a process that is appropriately treated as needed in the reservoir (5).

3 schematically shows a sludge treatment method using cavitation and an apparatus used therein. ①: inflow sludge, ②: reactor, ③: cavitation device, ④: sampling port, ⑤: treated sludge.

4 schematically illustrates a method of treating sludge using ozone and an apparatus used therein. ①: inflow sludge, ②: reaction tank, ③: gas-liquid mixing pump, ④: ozone generator, ⑤: sampling port, ⑥: treated sludge.

5 schematically shows a sludge treatment method using cavitation and ozone and an apparatus used therein. ①: inflow sludge, ②: cavitation device, ③: reactor, ④: gas-liquid mixing pump, ⑤: ozone generator, ⑥: sample collection port, ⑦: treatment sludge.

Claims (11)

A method of pretreating sewage sludge, the method comprising: treating sewage sludge with ozone generated from an ozone generator; And Treating the ozone treated sewage sludge by passing it through an orifice having a cross-sectional area smaller than the inlet at a high pressure of 2000 to 8000 psi to treat the ozone treated sewage sludge. A method of pretreating sewage sludge, the method comprising: treating sewage sludge by passing it through an orifice having a cross-sectional area smaller than the inlet at a high pressure of 2000 to 8000 psi; And treating the passed sewage sludge with ozone generated from an ozone generator. In the method for pretreatment of sewage sludge, ozone generated by the ozone generator between the orifice and the high pressure generator which passes through an orifice having a cross-sectional area smaller than the inlet at a high pressure of 2000 to 8000 psi and generates a high pressure of 2000 to 8000 psi Treating the sewage sludge by injecting the sewage sludge pre-treatment method characterized in that the ozone treated sewage sludge passes through the orifice and is further processed by hydraulic cavitation. The method according to any one of claims 1 to 3, further comprising an effective amount of hydrogen peroxide (H ₂ O ₂ ) in addition to the ozone supply; Sodium hydroxide (NaOH); Or sewage sludge pretreatment method characterized in that the hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) is supplied together. delete delete delete delete delete A sewage sludge treatment method comprising a sewage sludge pretreatment method, wherein the sewage sludge pretreatment method includes a sewage sludge pretreatment method according to any one of claims 1 to 3. delete

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