CA2147253A1 - Process for treating industrial waste waters with low concentrations of toxic organic pollutants - Google Patents
Process for treating industrial waste waters with low concentrations of toxic organic pollutantsInfo
- Publication number
- CA2147253A1 CA2147253A1 CA002147253A CA2147253A CA2147253A1 CA 2147253 A1 CA2147253 A1 CA 2147253A1 CA 002147253 A CA002147253 A CA 002147253A CA 2147253 A CA2147253 A CA 2147253A CA 2147253 A1 CA2147253 A1 CA 2147253A1
- Authority
- CA
- Canada
- Prior art keywords
- activated charcoal
- bar
- temperatures
- organic pollutants
- adsorption
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/06—Treatment of sludge; Devices therefor by oxidation
- C02F11/08—Wet air oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/26—Treatment of water, waste water, or sewage by extraction
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/36—Organic compounds containing halogen
Abstract
The invention describes an effective process which combines the adsorption on activated charcoal of toxic organic pollutants from waste water, the desorption of the pollutants in hot water, and the subsequent oxidative decomposition of the desorbed pollutants in a trickle bed reactor.
Fig. 1
Fig. 1
Description
-ILE. Pll`l ~ t~N[~LU 21~172S3 .. TE~XT JRANS~ATION
Process for Treating Industrial Waste Waters with Low Concentrations of Toxic Organic Pollutants The invention relates to a process for effectively removing organic pollutants from waste water flows. In particular, the invention relates to a process in which toxic organic pollutants are adsorbed and concentrated on granul~r activated charcoal in a first step, and a second step follows in which the organic pollutants are desorbed, so that the activated charcoal is regenerated, and the pollutants are subsequently decomposed in a 3-phase oxidation reactor.
Technical Background of the Invention Many waste water flows which originate in industrial activity contain organic pollutants that are either toxic or extrenlely difficult to decompose biologically, so that no direct biological treatment is possible. As an alternative in such cases, it can be necessary ~_, , 2197253 to use less common techniques, for example, chemical oxidation or wet-air oxidation, in order to oxidize the organic material contained in the waste water. As a means for purifying waste water, an alternative to non-catalytic wet-air oxidation is the oxidation of diluted hydrous solutions of organic pollutants using oxygen via a solid-matter catalyst (J. Levec, Appl. Catal., 63, 1990, p. 1; A. Pintar and J. Levec, J. Catal., 135, 1992, p. 345). In this process, organic substances are oxidized to carbon dioxide at substantially lower temperatures and pressures than in non-catalytic thermal processes. The key to effective catalytic oxidation, ho~ever, is the catalyst. Recently, a catalyst has been developed that promotes oxidation of organic substances in hydrous solutions below 200 C (DE 39 38 835 A1; EP 0 429 750 B1). With these new catalysts, a large area of application opens up for using the oxidation process to completely oxidize toxic organic substances in waste waters.
Adsorption with granulated activated charcoal is a proven method of purifying process water (W.W. Eckenfehler Jr. et al., Chemical Engineering, 2 September 1985, p. 60). Activated charcoal is especially effective in removing organic pollutants when the pollutants are dissolved in the waste water in small quantities. Through the coal adsorption process, the organic pollutants are also concentrated into the coal particles. Frequently, the coal exchange, the removal of used coal and the supply of fresh coal are the most critical parameters in operating the adsorption system and can be the determinant factors in operating costs. The in situ regeneration of used activated charcoal with steam or hot gas is effective in regenerating fluid-phase activated charcoal only to a limited extent. In the most frequently used '._ regeneration technique, the used coal is heated in a controlled atmosphere in a multistage or rotary kiln. Up to 10% of the coal is lost during such a reactivation process.
The process of the present invention permits activated charcoal to be regenerated within the adsorber without the removal of the coal from the latter. This is achieved by recycling hot water through the adsorber and the oxidation reactor at an increased temperature and increased pressure. During recycling, most of the organic pollutants are desorbed by the coal and released into the water; after this, they are oxidized through catalysis in a trickle bed reactor.
For optimum effect, the process according to the invention should be installed at the location in an industrial facility where waste water is created.
Brief Description of the Invention The process of the present invention consists of the following steps:
a) Adsorption step, in which waste water containing toxic organic pollutants and/or organic pollutants difficult to decompose biologically is run through a column (adsorber) loaded with activated charcoal until the coal bed is fully consumed, i.e., until its adsorption capacity has been used up. The inflow concentration can fluctuateconsiderably without endangering the target outflow levels. Adsorption is advantageously carried out at ambient pressure and ambient temperature. In fact,_ pressure has practically no influence on adsorption, although temperature undoubtedly does. Higher temperatures should therefore be avoided.
. . . _ . . _ ~ . . .
. ~
Cooling at the ambient temperature or at the usual cooling water temperature is not advisable, due to the required expenditure of energy. The possible temperature range is between 10 and 30 C.
b) Desorption/regeneration step, in which the used activated charcoal is regenerated in fluid-phase operation at temperatures from 80 to 200C and an increased pressure lying abo~e the steam pressure of the fluid. If possible, an overpressure of 30 bar (31 bar absolute) should not be exceeded. The flow of liquid within the adsorber can be directed upwards or downwards in the adsorption operating mode as well as in thedesorption/regeneration operating mode.
c) Oxidative decomposition step, in which the desorbed organic pollutants are oxidized to carbon dioxide in a trickle bed via a catalyst. An especially effective catalyst is described in I)E 39 38 835 A1 and EP 0 429 750 B1 and contains 30-50% by weight copper oxide, 40-50% by weight zinc oxide, 0-4% by weight chromium oxide and 5-15% by weight aluminum oxide. Oxidation is carried out in the liquid phase at increased pressure (up to 60 bar ovelpress~lre) and increased temperatures of at least 120 C to 250 C. In the oxidation reactor, the gaseous phase (air or oxygen) and the liquid phase can each flow upward or downward in parallel flow. The oxygen partial pressure should be at least 3 bar.
The process of the present invention is represented schematically in Figure 1. The waste water which contains solute toxic organic pollutants is ..
. . .
21q7253 conveyed through a conduit 1 via a 3-way valve (inlet valve 2) into the adsorber 3, which is loaded with granulated activated charcoal. The flow of liquid through the coal bed is forced by a pressure gradient. The consumption of the coal bed (loading with pollutants) is monitored through the appearance of the "breakthrough curve." After the coal bed becomes saturated with organic substances and the inlet valve 2 and the outlet valve 4, which are arranged in an outlet conduit 5 at the lower end of the adsorber 3, are closed, the adsorber 3 is heated to working temperature. At the same time, the preheater 13, which is connected to the adsorber 3 via a hot water supply conduit 15 containing a 3-way valve, is switched on.
The adsorber 3 is connected at its upper end to a hot water extraction conduit 7, in which there is a blocking valve 6 and which leads to a reactor 9. In turn, the reactor 9 is connected at its lower end to the preheater 13 via a tube. As soon as the water temperature in the adsorber 3 and the preheater 13 has reached the working temperature, the valves 6 and 14 are opened, and the hot water begins to be circulated by means of a pump 12 through the adsorber 3 and the reactor 9. After the hot circ~ ting water (recycling water) has reached the reaction temperature (120-250C), a flow containing oxygen (e.g., air) is introduced through a conduit 8 topside into the reactor 9. Advantageously, the pressure in both units (adsorber 3, reactor 9) is the same and measures, for example, 20 bar or even as much as 30 bar (ove.pres~-lre). The reactor 9 works under 2-phase flow conditions, while only one phase (liquid) occurs in the adsorber 3. Due to the increased temperature in the adsorber 3, the organic substances which were adsorbed at the ambient temperature are now desorbed and released into the hot recycling water; they are subsequently oxidized to carbon dioxide in the trickle bed reactor 9. The flow of recycling water treated in this manner makes its way behind the reactor 9 into a gas/liquid separator 10, so that the gas phase (especially ` ,~, the CO2 which has formed and the oxygen-containing gas which has not been consumed) can be extracted through an exhaust conduit 11, while the pollutant-free recycling water is conveyed back into the preheater 13 via the pump 12. During desorptive operation, the flow of waste water to be purified is conveyed ~ia the 3-way valve 2 through the conduit 16 to a second adsorption column (not shown) connected in a parallel hshion. The desorption/regeneration and the associated oxidative reaction are ended as soon as the residual content of organic substances in the recycling water drops below a certain concentration limit.
It must be emphasized that the organic substances do not have to be fully desorbed by the activated charcoal or completely oxidized in the reactor 9. In such a case, the adsorption capacity of the activated charcoal is simply reduced accordingly. As a result, the capacity of the activated charcoal to remove organic substances at low concentrations in the adsorption step can be reduced.
The process of the present invention, which consists of a combination of adsorption and oxidative regeneration, utilizes the advantages of both of these individual processes. For example, the regeneration of the coal can be carried out in situ without any loss of coal, so that no coal preparation is needed. The discharged treated water is not polluted by metal cations which might possibly wash out of the catalyst, because the cations remain in the recycling water and also act there as a homogeneous catalyst. The deactivation of the catalyst is significantly increased and the useful life of the catalyst is substantially lengthened in the process according to the invention, compared to a process without prior adsorption (i.e., direct oxida~ion). Furthermore, compared to direct oxidation, the prior concentration of organic pollutants on activated charcoal results in higher oxidation rates and ' thus in shorter catalyst beds.
Detailed Description of the Invention ~xample 1: Regeneration of Used Activated charcoal with Hot Pressurized Water A hydrous phenol solution with a concentration of 1.0 g/l was used as the waste water in a test. The solution was introduced at a flow rate of 3 I/h into a stainless-steel adsorption column (inner diameter 34 mm), which was filled ~ith 125 g activated charcoal (bed height 380 mm) with a particle size of 1.6 mm. The consumption of the activated charcoal ~as monitored by means of phenol concentration measurements (HPLC) in the adsorber outflow.
As soon as phenol was found in the outflow (concentration below 0.2 mg/l), the activated charcoal was assumed to be saturated by the polluting substances. The adsorption process was carried out at ambient pressure (1 bar absolute) and ambient temperature (c. 22 C).
Desorption/regeneration of the used activated charcoal was carried out by means of hot water (150 C; 10 bar ovel~res~-lre) flowing through the adsorber at a rate of 3 l/h. The phenol concentration in the discharged water was monitored by means of HPLC and is indicated in the graph in Fig. 2 as a function of time (Curve I). After the phenol concentration dropped below 1.5 g/l, the desorption/regeneration process was ended. Results showed that 26.7 g phenol was adsorbed on the activated charcoal at room temperature; after the desorption/regeneration step was carried out, 5.6 g phenol still remained adsorbed on the coal.
This means that under the conditions used approximately 80% of the original activated charcoal capacity was again obtained. Catalytic treatment of the hot water loaded with phenol according to the present invention was 21~7253 not yet carried out in this example.
xample 2: Regeneration of Used Activated charcoal with Hot Water and Simultaneous Oxidative Decomposition of Desorbed Phenol The activated charcoal bed saturated with phenol from Example 1 was regenerated by means of hot water, which was circulated through the adsorber and the trickle bed reactor according to the invention. The flow rate of the recycling water was set at 2 I/h. After the recycling water had reached the predetermined temperature of 150 C, a flow of oxygen was introduced into the trickle bed reactor at a rate of 2 I/min. The reactor (inner diameter 34 mm) was loaded with 730 g of a catalyst (bed height 810 mm) as described in DE 39 38 835 A1 and EP
0 429 750 B1. The operating pressure in the adsorber and in the reactor was 10 bar (ovel~ressllre). The hot water (2.51) circulated for a period of 10 h. During this time, the phenol concentration in the hot recycling water, which was monitored by means of an HPLC
analyzer (high performance liquid chromatography) and a TOC analyzer kotal organic coal), dropped to 0.8 g/l (Curve II in Figure 2), which corresponds roughly to a 90% restoration of the original activated charcoal adsorption capacity. After 5 subsequent adsorption/regeneration/oxidation cycles, the adsorption characteristics of the activated charcoal had not changed. The concentration of leached-out copper and zinc ions in the recycled water was measured at 20 and 32 mg/l, respectively, by means of AAS (atomic absorption spectroscopy). In each case, the treated water discharged from the adsorption stage contained neither phenol nor copper or zinc.
Process for Treating Industrial Waste Waters with Low Concentrations of Toxic Organic Pollutants The invention relates to a process for effectively removing organic pollutants from waste water flows. In particular, the invention relates to a process in which toxic organic pollutants are adsorbed and concentrated on granul~r activated charcoal in a first step, and a second step follows in which the organic pollutants are desorbed, so that the activated charcoal is regenerated, and the pollutants are subsequently decomposed in a 3-phase oxidation reactor.
Technical Background of the Invention Many waste water flows which originate in industrial activity contain organic pollutants that are either toxic or extrenlely difficult to decompose biologically, so that no direct biological treatment is possible. As an alternative in such cases, it can be necessary ~_, , 2197253 to use less common techniques, for example, chemical oxidation or wet-air oxidation, in order to oxidize the organic material contained in the waste water. As a means for purifying waste water, an alternative to non-catalytic wet-air oxidation is the oxidation of diluted hydrous solutions of organic pollutants using oxygen via a solid-matter catalyst (J. Levec, Appl. Catal., 63, 1990, p. 1; A. Pintar and J. Levec, J. Catal., 135, 1992, p. 345). In this process, organic substances are oxidized to carbon dioxide at substantially lower temperatures and pressures than in non-catalytic thermal processes. The key to effective catalytic oxidation, ho~ever, is the catalyst. Recently, a catalyst has been developed that promotes oxidation of organic substances in hydrous solutions below 200 C (DE 39 38 835 A1; EP 0 429 750 B1). With these new catalysts, a large area of application opens up for using the oxidation process to completely oxidize toxic organic substances in waste waters.
Adsorption with granulated activated charcoal is a proven method of purifying process water (W.W. Eckenfehler Jr. et al., Chemical Engineering, 2 September 1985, p. 60). Activated charcoal is especially effective in removing organic pollutants when the pollutants are dissolved in the waste water in small quantities. Through the coal adsorption process, the organic pollutants are also concentrated into the coal particles. Frequently, the coal exchange, the removal of used coal and the supply of fresh coal are the most critical parameters in operating the adsorption system and can be the determinant factors in operating costs. The in situ regeneration of used activated charcoal with steam or hot gas is effective in regenerating fluid-phase activated charcoal only to a limited extent. In the most frequently used '._ regeneration technique, the used coal is heated in a controlled atmosphere in a multistage or rotary kiln. Up to 10% of the coal is lost during such a reactivation process.
The process of the present invention permits activated charcoal to be regenerated within the adsorber without the removal of the coal from the latter. This is achieved by recycling hot water through the adsorber and the oxidation reactor at an increased temperature and increased pressure. During recycling, most of the organic pollutants are desorbed by the coal and released into the water; after this, they are oxidized through catalysis in a trickle bed reactor.
For optimum effect, the process according to the invention should be installed at the location in an industrial facility where waste water is created.
Brief Description of the Invention The process of the present invention consists of the following steps:
a) Adsorption step, in which waste water containing toxic organic pollutants and/or organic pollutants difficult to decompose biologically is run through a column (adsorber) loaded with activated charcoal until the coal bed is fully consumed, i.e., until its adsorption capacity has been used up. The inflow concentration can fluctuateconsiderably without endangering the target outflow levels. Adsorption is advantageously carried out at ambient pressure and ambient temperature. In fact,_ pressure has practically no influence on adsorption, although temperature undoubtedly does. Higher temperatures should therefore be avoided.
. . . _ . . _ ~ . . .
. ~
Cooling at the ambient temperature or at the usual cooling water temperature is not advisable, due to the required expenditure of energy. The possible temperature range is between 10 and 30 C.
b) Desorption/regeneration step, in which the used activated charcoal is regenerated in fluid-phase operation at temperatures from 80 to 200C and an increased pressure lying abo~e the steam pressure of the fluid. If possible, an overpressure of 30 bar (31 bar absolute) should not be exceeded. The flow of liquid within the adsorber can be directed upwards or downwards in the adsorption operating mode as well as in thedesorption/regeneration operating mode.
c) Oxidative decomposition step, in which the desorbed organic pollutants are oxidized to carbon dioxide in a trickle bed via a catalyst. An especially effective catalyst is described in I)E 39 38 835 A1 and EP 0 429 750 B1 and contains 30-50% by weight copper oxide, 40-50% by weight zinc oxide, 0-4% by weight chromium oxide and 5-15% by weight aluminum oxide. Oxidation is carried out in the liquid phase at increased pressure (up to 60 bar ovelpress~lre) and increased temperatures of at least 120 C to 250 C. In the oxidation reactor, the gaseous phase (air or oxygen) and the liquid phase can each flow upward or downward in parallel flow. The oxygen partial pressure should be at least 3 bar.
The process of the present invention is represented schematically in Figure 1. The waste water which contains solute toxic organic pollutants is ..
. . .
21q7253 conveyed through a conduit 1 via a 3-way valve (inlet valve 2) into the adsorber 3, which is loaded with granulated activated charcoal. The flow of liquid through the coal bed is forced by a pressure gradient. The consumption of the coal bed (loading with pollutants) is monitored through the appearance of the "breakthrough curve." After the coal bed becomes saturated with organic substances and the inlet valve 2 and the outlet valve 4, which are arranged in an outlet conduit 5 at the lower end of the adsorber 3, are closed, the adsorber 3 is heated to working temperature. At the same time, the preheater 13, which is connected to the adsorber 3 via a hot water supply conduit 15 containing a 3-way valve, is switched on.
The adsorber 3 is connected at its upper end to a hot water extraction conduit 7, in which there is a blocking valve 6 and which leads to a reactor 9. In turn, the reactor 9 is connected at its lower end to the preheater 13 via a tube. As soon as the water temperature in the adsorber 3 and the preheater 13 has reached the working temperature, the valves 6 and 14 are opened, and the hot water begins to be circulated by means of a pump 12 through the adsorber 3 and the reactor 9. After the hot circ~ ting water (recycling water) has reached the reaction temperature (120-250C), a flow containing oxygen (e.g., air) is introduced through a conduit 8 topside into the reactor 9. Advantageously, the pressure in both units (adsorber 3, reactor 9) is the same and measures, for example, 20 bar or even as much as 30 bar (ove.pres~-lre). The reactor 9 works under 2-phase flow conditions, while only one phase (liquid) occurs in the adsorber 3. Due to the increased temperature in the adsorber 3, the organic substances which were adsorbed at the ambient temperature are now desorbed and released into the hot recycling water; they are subsequently oxidized to carbon dioxide in the trickle bed reactor 9. The flow of recycling water treated in this manner makes its way behind the reactor 9 into a gas/liquid separator 10, so that the gas phase (especially ` ,~, the CO2 which has formed and the oxygen-containing gas which has not been consumed) can be extracted through an exhaust conduit 11, while the pollutant-free recycling water is conveyed back into the preheater 13 via the pump 12. During desorptive operation, the flow of waste water to be purified is conveyed ~ia the 3-way valve 2 through the conduit 16 to a second adsorption column (not shown) connected in a parallel hshion. The desorption/regeneration and the associated oxidative reaction are ended as soon as the residual content of organic substances in the recycling water drops below a certain concentration limit.
It must be emphasized that the organic substances do not have to be fully desorbed by the activated charcoal or completely oxidized in the reactor 9. In such a case, the adsorption capacity of the activated charcoal is simply reduced accordingly. As a result, the capacity of the activated charcoal to remove organic substances at low concentrations in the adsorption step can be reduced.
The process of the present invention, which consists of a combination of adsorption and oxidative regeneration, utilizes the advantages of both of these individual processes. For example, the regeneration of the coal can be carried out in situ without any loss of coal, so that no coal preparation is needed. The discharged treated water is not polluted by metal cations which might possibly wash out of the catalyst, because the cations remain in the recycling water and also act there as a homogeneous catalyst. The deactivation of the catalyst is significantly increased and the useful life of the catalyst is substantially lengthened in the process according to the invention, compared to a process without prior adsorption (i.e., direct oxida~ion). Furthermore, compared to direct oxidation, the prior concentration of organic pollutants on activated charcoal results in higher oxidation rates and ' thus in shorter catalyst beds.
Detailed Description of the Invention ~xample 1: Regeneration of Used Activated charcoal with Hot Pressurized Water A hydrous phenol solution with a concentration of 1.0 g/l was used as the waste water in a test. The solution was introduced at a flow rate of 3 I/h into a stainless-steel adsorption column (inner diameter 34 mm), which was filled ~ith 125 g activated charcoal (bed height 380 mm) with a particle size of 1.6 mm. The consumption of the activated charcoal ~as monitored by means of phenol concentration measurements (HPLC) in the adsorber outflow.
As soon as phenol was found in the outflow (concentration below 0.2 mg/l), the activated charcoal was assumed to be saturated by the polluting substances. The adsorption process was carried out at ambient pressure (1 bar absolute) and ambient temperature (c. 22 C).
Desorption/regeneration of the used activated charcoal was carried out by means of hot water (150 C; 10 bar ovel~res~-lre) flowing through the adsorber at a rate of 3 l/h. The phenol concentration in the discharged water was monitored by means of HPLC and is indicated in the graph in Fig. 2 as a function of time (Curve I). After the phenol concentration dropped below 1.5 g/l, the desorption/regeneration process was ended. Results showed that 26.7 g phenol was adsorbed on the activated charcoal at room temperature; after the desorption/regeneration step was carried out, 5.6 g phenol still remained adsorbed on the coal.
This means that under the conditions used approximately 80% of the original activated charcoal capacity was again obtained. Catalytic treatment of the hot water loaded with phenol according to the present invention was 21~7253 not yet carried out in this example.
xample 2: Regeneration of Used Activated charcoal with Hot Water and Simultaneous Oxidative Decomposition of Desorbed Phenol The activated charcoal bed saturated with phenol from Example 1 was regenerated by means of hot water, which was circulated through the adsorber and the trickle bed reactor according to the invention. The flow rate of the recycling water was set at 2 I/h. After the recycling water had reached the predetermined temperature of 150 C, a flow of oxygen was introduced into the trickle bed reactor at a rate of 2 I/min. The reactor (inner diameter 34 mm) was loaded with 730 g of a catalyst (bed height 810 mm) as described in DE 39 38 835 A1 and EP
0 429 750 B1. The operating pressure in the adsorber and in the reactor was 10 bar (ovel~ressllre). The hot water (2.51) circulated for a period of 10 h. During this time, the phenol concentration in the hot recycling water, which was monitored by means of an HPLC
analyzer (high performance liquid chromatography) and a TOC analyzer kotal organic coal), dropped to 0.8 g/l (Curve II in Figure 2), which corresponds roughly to a 90% restoration of the original activated charcoal adsorption capacity. After 5 subsequent adsorption/regeneration/oxidation cycles, the adsorption characteristics of the activated charcoal had not changed. The concentration of leached-out copper and zinc ions in the recycled water was measured at 20 and 32 mg/l, respectively, by means of AAS (atomic absorption spectroscopy). In each case, the treated water discharged from the adsorption stage contained neither phenol nor copper or zinc.
Claims (4)
1. Process for the treatment of industrial waste water flows which contain organic pollutants in low concentration, characterized by the following process steps:
a) Adsorption of organic pollutants from the waste water flow on granular activated charcoal carried out at temperatures between 10 and 30°C;
b) Desorption of the organic pollutants from the activated charcoal and in situ regeneration of the activated charcoal by means of hot water which is circulatedthrough the active coal bed (adsorber) and an oxidation reactor at increased pressures up to 30 bar (overpressure) and temperatures between 80 and 200°C.
c) Decomposition of the organic substances desorbed from the activated charcoal through catalytic fluid-phase oxidation in a 3-phase reactor via a catalyst, whereby increased pressures of up to 60 bar (overpressure) and temperatures between 120 and 250°C prevail at a minimum oxygen partial pressure of 3 bar and the flowing phases in the oxidation reactor are directed either upwards or downwards, respectively, in parallel flow.
a) Adsorption of organic pollutants from the waste water flow on granular activated charcoal carried out at temperatures between 10 and 30°C;
b) Desorption of the organic pollutants from the activated charcoal and in situ regeneration of the activated charcoal by means of hot water which is circulatedthrough the active coal bed (adsorber) and an oxidation reactor at increased pressures up to 30 bar (overpressure) and temperatures between 80 and 200°C.
c) Decomposition of the organic substances desorbed from the activated charcoal through catalytic fluid-phase oxidation in a 3-phase reactor via a catalyst, whereby increased pressures of up to 60 bar (overpressure) and temperatures between 120 and 250°C prevail at a minimum oxygen partial pressure of 3 bar and the flowing phases in the oxidation reactor are directed either upwards or downwards, respectively, in parallel flow.
2. Process as in Claim 1 -characterized by the following steps: -a) Adsorption of phenol from a hydrous solution which contains 0.1 to 5 g phenol per liter of water, in a fixed bed adsorber which is loaded with activated charcoal, whereby the adsorption takes place at atmospherlc pressure and temperatures between 15 and 25°C;
b) Desorption of the phenol from the activated charcoal in hot recycling water and in situ regeneration of the activated charcoal bed at increased pressures up to 20 bar (overpressure) and temperatures in the range of 130-160°C;
c) Decomposition of the desorbed phenol through catalytic liquid-phase oxidationto carbon dioxide in the trickle bed reactor via a catalyst at increased pressures up to 20 bar (overpressure) and temperatures between 130 and 160°C and anoxygen partial pressure of at least 3 bar.
b) Desorption of the phenol from the activated charcoal in hot recycling water and in situ regeneration of the activated charcoal bed at increased pressures up to 20 bar (overpressure) and temperatures in the range of 130-160°C;
c) Decomposition of the desorbed phenol through catalytic liquid-phase oxidationto carbon dioxide in the trickle bed reactor via a catalyst at increased pressures up to 20 bar (overpressure) and temperatures between 130 and 160°C and anoxygen partial pressure of at least 3 bar.
3. Process as in one of the Claims 1 or 2, characterized by the fact that the liquid-phase oxidation is carried out with a catalyst which contains 20-40% by weight CuO, 15-25% by weight ZnO, 0-4% by weight Cr2O2 and 20-40% by weight AI2O3.
4. Process as in one of the Claims 1 to 3, characterized by the fact -that during desorption and liquid-phase oxidation the same overpressure is established in the adsorber and in the 3-phase reactor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SIP9200263 | 1992-10-19 | ||
| SI9200263A SI9200263B (en) | 1992-10-19 | 1992-10-19 | Process for catalytic oxidation of organic impurities in waste waters |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2147253A1 true CA2147253A1 (en) | 1994-04-28 |
Family
ID=20431016
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002147253A Abandoned CA2147253A1 (en) | 1992-10-19 | 1993-10-19 | Process for treating industrial waste waters with low concentrations of toxic organic pollutants |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0664771B1 (en) |
| JP (1) | JPH08506044A (en) |
| AT (1) | ATE148429T1 (en) |
| AU (1) | AU5368394A (en) |
| CA (1) | CA2147253A1 (en) |
| DE (1) | DE59305357D1 (en) |
| DK (1) | DK0664771T3 (en) |
| ES (1) | ES2096954T3 (en) |
| FI (1) | FI951788A0 (en) |
| SI (1) | SI9200263B (en) |
| WO (1) | WO1994008905A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU776320B2 (en) * | 2000-05-11 | 2004-09-02 | Trident Trade Waste Treatment Pty. Ltd. | Waste water treatment apparatus |
| JP2017000992A (en) * | 2015-06-15 | 2017-01-05 | 東洋紡株式会社 | Water treatment system |
| CN114684952B (en) * | 2020-12-31 | 2023-08-01 | 中国石油化工股份有限公司 | Method and device for treating low COD sewage |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI64793C (en) * | 1977-01-27 | 1984-01-10 | Degussa | FOERFARANDE FOER RENING AV AVFALLSVATTEN SOM INNEHAOLLER FENOLFENOLDERIVAT ELLER FENOL OCH FORMALDEHYD |
| DE3938835A1 (en) * | 1989-11-23 | 1991-05-29 | Sued Chemie Ag | METHOD FOR THE OXIDATION OF ORGANIC IMPURITIES IN SEWAGE |
-
1992
- 1992-10-19 SI SI9200263A patent/SI9200263B/en unknown
-
1993
- 1993-10-19 CA CA002147253A patent/CA2147253A1/en not_active Abandoned
- 1993-10-19 DK DK93924005.7T patent/DK0664771T3/en active
- 1993-10-19 EP EP93924005A patent/EP0664771B1/en not_active Expired - Lifetime
- 1993-10-19 AU AU53683/94A patent/AU5368394A/en not_active Abandoned
- 1993-10-19 JP JP6509518A patent/JPH08506044A/en active Pending
- 1993-10-19 ES ES93924005T patent/ES2096954T3/en not_active Expired - Lifetime
- 1993-10-19 AT AT93924005T patent/ATE148429T1/en not_active IP Right Cessation
- 1993-10-19 WO PCT/DE1993/001016 patent/WO1994008905A1/en active IP Right Grant
- 1993-10-19 DE DE59305357T patent/DE59305357D1/en not_active Expired - Fee Related
-
1995
- 1995-04-13 FI FI951788A patent/FI951788A0/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| AU5368394A (en) | 1994-05-09 |
| ES2096954T3 (en) | 1997-03-16 |
| EP0664771B1 (en) | 1997-01-29 |
| SI9200263A (en) | 1994-06-30 |
| FI951788A (en) | 1995-04-13 |
| FI951788A0 (en) | 1995-04-13 |
| DE59305357D1 (en) | 1997-03-13 |
| WO1994008905A1 (en) | 1994-04-28 |
| ATE148429T1 (en) | 1997-02-15 |
| EP0664771A1 (en) | 1995-08-02 |
| JPH08506044A (en) | 1996-07-02 |
| SI9200263B (en) | 2000-04-30 |
| DK0664771T3 (en) | 1997-02-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |