CS262746B1 - A method of activating biological wastewater treatment using carbon particles generated in the process of partial oxidation of petroleum distillation residues - Google Patents

Abstract

A method of activating biological treatment of wastewater using carbon particles produced in the process of partial oxidation of oil or tar distillation residues, in which the wastewater is introduced into the activated sludge biological treatment process, where carbon particles are simultaneously introduced, preferably in the form of a suspension, in an amount of 0.05 to 0.5 kg of carbon/m3 of wastewater and together with the activated sludge they participate in the treatment process with a retention time of 3 to 24 hours and are maintained at a concentration of 0.5 to 5.0 g.l”1 by recirculation. It is preferable to disperse the carbon particles by introducing oxygen or air.

Description

The invention relates to the use of specific properties of carbon particles formed in the process of partial oxidation of petroleum or tar distillation residues in the biological treatment of wastewater.

In the biological treatment of wastewater containing substances that are difficult to biodegrade, such as water from oil and coal processing, it is necessary to ensure a considerably long contact time between the wastewater and the biomass in the reactor in order to achieve the desired cleaning effect. In the treatment of some types of wastewater, especially industrial wastewater, a phenomenon occurs when the wastewater effluent shows a good cleaning effect according to BSKg, but the COD value of the effluent is very high, on the order of

-3 g. m, and the effluent shows strong sensory defects (color, odor). This phenomenon is mainly caused by non-biodegradable substances present in the incoming wastewater, or metabolites formed during biological treatment.

When treating wastewater _containing practically non-biodegradable substances as part of the pollution, these substances penetrate the treatment plant into the recipient without a significant reduction in their content.

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These disadvantages are eliminated by a method of wastewater treatment using carbon particles produced in the process of partial oxidation of petroleum distillation residues, which, according to the invention, consists in the fact that wastewater is introduced into a biological treatment process with biological activated sludge with the addition of carbon particles produced in the partial oxidation of petroleum and/or tar distillation residues, preferably in the form of an aqueous suspension resulting from this process, in an amount of 0.005 to 0.? kg carbon • ^m3 of wastewater, preferably 0.05 to 0.166 kg carbon per 1 ^m3 of wastewater and together with biological activated sludge participate in the purification process with a retention time of 3-24 hours, preferably 5-15 hours and recirculation is maintained in the range of 0.5 to 5.0, preferably 1.5 to 2.5 kg, 1. The carbon particles are dispersed when introduced into the wastewater, preferably with the addition of oxygen or air.

The specific properties of carbonaceous particles resulting from the partial oxidation of petroleum or tar distillation residues are determined by the conditions of their formation and are characterized by a microscopic structure of graphitic nature, a basic particle size of 1 to 2 . ÍO“ ⁷ m, a specific surface area of 700 to 1200 m ² . g” ¹ , a porosity of 85 to 90%, the presence of micro and macropores and trace amounts of metals present in the particles in degraded organometallic form. Furthermore, these particles are characterized by the ability to form agglomerates of basic particles of considerable size in an aqueous suspension, which allows their separation by conventional hydroseparation procedures. These particles leave the process of partial oxidation of petroleum distillation residues in the form of a pumpable aqueous suspension, which can be used for direct dosing of carbonaceous particles into the biological treatment process, or at least a proportional part of the carbonaceous particles into the stream of wastewater supplied before the treatment process. The supply pipe or upstream tank can be used to capture part of the pollution, or by adding air or oxygen to the pipe or tank, catalytic oxidation of part of the pollution that could have an adverse effect on biological treatment can be used.

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For perfect dispersion of carbon particles, possibly also air or oxygen into the stream of supplied wastewater, it is advantageous to use turbulence when the mixture passes through a centrifugal pump, or behind the pump or in another suitable way. The usable dose of carbon particles from the partial oxidation of petroleum distillation residues into the cleaning process varies depending on the type of wastewater, the type of treatment process and the ratio between the maintained sludge age and the hydraulic retention time of 0.005 to 0.3 kg. m $ of supplied wastewater. This corresponds to the dose of a waste aqueous suspension of carbon particles from the partial oxidation of petroleum distillation residues with a concentration of 1.5% by weight of 1 m of this suspension per 50 to 3,000 m of supplied wastewater. The preferred dose of carbon particles is usually 0.05 to 0.166 kg. m” ³ of supplied wastewater, when dosing a suspension of 1.5% by weight, the preferred ratio is 1 m of suspension per 90 to 300 m of supplied wastewater, when dosing a more diluted or concentrated suspension, resulting from the process of partial oxidation of oil or tar residues, the ratio changes proportionally. A sufficient concentration of carbon particles is achieved by recirculating them together with biological sludge and increasing the age of the sludge. The resulting steady concentration of carbon particles corresponds to the technological parameters and is governed by the formula x _A · A ^x c “ --------* where

T x is the steady-state concentration of carbon particles in the cleaning process, x _A is the concentration of carbon particles in the influent, or the concentration corresponding to the dose of carbon particles related to the influent, A is the age of the sludge in the system, T is the hydraulic retention time of the wastewater in the reaction tank. Carbon particles from the partial oxidation of petroleum distillation residues together with biological sludge create specific conditions for the cleaning process. The joint movement of carbon particles and biological sludge during the ongoing assimilation of the organic substrate creates a specific mixture, where microorganisms are both captured on agglomerates of carbon particles and freely dispersed and further form flakes in which carbon microparticles are present. Carbon microparticles are also freely dispersed to a certain extent into the reaction medium, or form agglomerates.

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The representation of active components, i.e. agglomerates of carbon particles with captured microorganisms, freely dispersed microorganisms, flakes of microorganisms with carbon microparticles and freely dispersed carbon microparticles, is influenced, among other things, by the technological arrangement and parameters of the cleaning process and the aeration method used, on which the achieved velocity gradients in the reaction mixture depend and thus the ability to improve agglomeration or break up the resulting agglomerates. The main mechanisms reducing the pollution content are: biological assimilation of organic pollution present in the solution and captured in the biological sludge flakes, sorption of pollution on carbon particles, biological assimilation of pollution sorption captured on carbon particles, catalytic oxidation of the present pollution by the action of trace amounts of metals present in carbon particles and released into the reaction mixture and . biological assimilation of reaction products of catalytic oxidation.

In this specific mixture, the interaction of the participating components and the interaction of the mechanisms removing pollution from wastewater leads to increased efficiency and acceleration of the cleaning process.

The method according to the invention and the effect achieved are shown in the following examples.

Example 1 —1

Wastewater from oil and tar processing with a COD of 950 mg. 1 was subjected to sorption purification using carbon particles generated in the process of partial oxidation of oil and/or distillation residues. Carbon particles were added to the wastewater at various final concentrations and the mixture was intensively mixed for 15 minutes. The sorption resulted in a reduction in the COD values contained in the water. The results are shown in the table:

concentration of carbon particles /g . I ¹ / 0 0.3 0.9 1.2 1.7 decrease in COD after 15 minutes /%/ 0 7.5 16.7 25.8 31.2

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Wastewater from oil and/or tar processing with COD

OOO mg . 1 was mixed in various proportions with carbon particles and then aerated. The combined effect of sorption and catalytic oxidation resulted in a reduction in COD in the effluent. The results are shown in the table:

Concentration of carbon particles /g . I” ¹ / 0 0.3 0.9 1.2. 1.7 COD reduction in % after 1 hour θ,7 12.5 18.8 24.3 27.5 COD reduction in % 23.5 27.5 32.0 42.5 51.5

after 5 o'clock

Example 3

A batch kinetic test was used to verify the biological treatment of wastewater from oil and tar processing. The tests were carried out in parallel at a constant concentration of activated sludge x = 2.0 g 1** and at different concentrations of carbon particles. The tested mixtures were aerated in flasks and samples were taken at selected time intervals, in which COD was determined after filtration.

The course of the experiment is illustrated in the table:

Attempt Time 0, 1, :-2^3^ COD /mg • 1 / ..24 _tons _ Act, sludge + waste, water 930 350 230 140 130 125 120 Act, sludge + waste, water 860 250 180 120 - - - + 0.27g carbon . I ¹ Act, sludge + waste, water 780 205 150 105 95 85 55 + 0.93 g particles • l^carbon Act, sludge + waste, water 695 205 140 75 65 60 - + 1.19 g particles • l~^carbon

Continued tables: 262,746 TIME θ· 1* 2, 3. 4» 5. 24. Attempt COD /mg . Γ ¹ / Act. kal + waste, water 650 195 135 75 50 45 45 + 1.67 grams . l" ¹ carbon particles

The increase in efficiency of the system with a concentration of 1.67 g. l of carbonaceous particles from the partial oxidation of petroleum distillation residues compared to the conventional system with only activated sludge is 65% after 5 hours, and 62.5% after 24 hours.

In the monitored system with carbon particle concentration *1

1.67 g, 1 under the experimental conditions the purification process was practically completed after 5 hours.

Example 4

In parallel/continuously operating laboratory models of biological treatment plants, wastewater from oil and tar processing was treated. The models had the same activation mixture retention time of 13 hours, the same sludge age A = 5 days, and the return sludge is recirculated with recycle in proportion to the inflow.

R = 1. In the first model, the wastewater was treated by a conventional activation process with dosing of FeSO. , 7 H _o 0 to the inflow -1 ⁴ at a level of 200 mg . 1 . In the second model, the wastewater was treated by activated sludge, to which an aqueous suspension was continuously pumped at a dose of 0.215 g of carbon particles per 1 1 of incoming wastewater. At a sludge age of A = 5 days, a uniform concentration of carbon particles in the activation mixture was established at a level of 2 g . 1 . At an input wastewater concentration in the range of 1,650 - 2,000 mg . 1 , the increase in the efficiency of the process using carbon particles compared to the comparative process represented an average of 38% relative. Water polluted by the activation process using carbon particles was colorless and odorless.

Claims (3)

A method of activating biological wastewater treatment using carbonaceous particles resulting from the partial oxidation process of petroleum and / or tar distillation residues; characterized in that the waste water is fed to an activated sludge biological treatment process which is simultaneously fed with carbon particles resulting from the partial oxidation of petroleum and / or tar distillation residues, preferably in the form of a slurry leaving this process, in an amount of 0.005 to 0.5 kg carbon per m ^{3 of} waste water, preferably 0.05 to 0.166 kg carbon per m ^{3 of} waste water and together with activated sludge participate in a purification process with a residence time of 3 to 24 hours, preferably 5 to 15 hours and the recirculation is maintained at a concentration of 0 5 to 5.0 g l ^"1, preferably 1.5 to 2.5 g · l" ¹ 2. A method according to claim 1, wherein the carbon particles or at least a proportion thereof are dispersed when introduced into the waste water or into one of the waste water streams, preferably by introducing oxygen or air. Printed by Moravian printing works, center. 11 100, People's Miles Class 3, Olomouc Price: 2,40 CZK