CS241619B1 - Liquidation method of sludges produced at waste waters purification process - Google Patents

Abstract

The invention relates to a method of disposal primary and biological sludge formed in the wastewater treatment process, which retain bound waste water at sludge in the mixture with solid wastes from combustion and / or gasification of fossil fuels put into a mixer in which it is mechanically it excites and releases the water from which it is made organic and inorganic sorbents are irreversible on the active surface of solid wastes and together they are led to the depot where it will occur for aerobic treatment of residual impurities.

Description

(54) Method of disposal of sludge arising from the waste water treatment process

The invention relates to a method of disposal of primary and biological sludge generated in wastewater treatment process, which retain bound waste water, in which the sludges are mixed _{in the} solid waste from the combustion and / or gasification of fossil fuel introduced into the mixer in which the mechanically disrupted and releases water from which the organic and inorganic substances are irreversibly absorbed on the active surface of the solid waste and taken together to a dump where the remaining impurities are aerobically cleaned.

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The invention relates to a process for the disposal of sludge resulting from the waste water treatment process, in particular primary sludge, i.e., raw sludge formed by settling from water, and biological sludge.

The sludge settles in sewage treatment plants in the form of raw (primary) sludge in sedimentation tanks and in biological treatment in the form of biological sludge in sedimentation tanks. Because of their defect, which is largely due to colloidal bound water, capillary forces bound water and water bound in the cell mass, which is released only after the cell membrane has been disrupted, these sludges need to be treated by other technological procedures.

All known processes have a number of disadvantages. For example, the most commonly used process of thickening sludge, digestion, re-thickening the digested residue, and depositing it in the soil requires the construction of investment-intensive equipment.

Another process in which the sludge is drained and incinerated is not only expensive to invest, but also consumes fuel and energy.

The last procedure, which removes the shortcomings of the previous two processes, uses the hydraulic transport of ash from power plants and gas plants / waste from incineration and fossil fuel / to deposition to remove biological sludge or its mixture and primary sludge. it is biological and thus retained in the ashes

- 2 241 619 sludges are subject to a gradual anaerobic decomposition in which methane fermentation occurs, releasing into the atmosphere, in addition to methane, odorous substances such as skatol and indole. The use of this procedure also causes secondary pollution of floatable water, either of which all or part of it flows into public streams. These disadvantages are solved by a method for the disposal of sludge resulting from the waste water treatment process, in particular of primary sludge resulting from sedimentation from water and biological sludge, which according to the invention consists in mixing the biological sludge together with the primary sludge with solid incineration waste. and / gasification of fossil fuels in a proportion from 3.5 to 18.5 mg / g, preferably 5.1 to 9.6 mg / g, then the primary and biological sludges mechanically dissociated by stirring in the mixing ReynolcčUvě number R _{M is} equal to 1 · 10 ^ to 1. 10? preferably 1. 10 ° to 1. 10 ° by releasing the water bound outside the sludge, while the organic and inorganic substances contained in the water are absorbed on the active surface of the waste. Stirring and disruption takes place in the water used for the hydraulic transport of the poles at a solid to liquid ratio of 1: 15 to 1; 25 is preferably 1:20. The mixture is set to settle, where the organic residues in the water are purified aerobically with oxygen in the water.

In addition to avoiding secondary water contamination from organic anaerobic decomposition products and methane releases, the process described above is not energy-intensive, but can be realized with minimal investment cost in an existing plant.

The method of applying the described procedure will be apparent from the following examples.

Example 1

In each of the two five-liter containers A, B was measured

500 ml water from hydraulic transport of solid waste from combustion and gasification of fossil fuels. Furthermore, a mixture of sludge from primary sedimentation, flotation and biological sludge was dosed into each vessel

241 619 and a mixture of heating ashes and cinder in an amount of 3.5 mg sludge per 1 g of ash.

The resulting chemical oxygen demand (COD) of this mixture was 32.5 mg / L, the biochemical oxygen demand over 5 days (BODg) was 12.64.

The contents of vessel A were transferred to a mixer in which the mixture was disintegrated at R e = 1, 10. The next step was 30 min. agitated on a mixer at a peripheral speed of the mixer of 1.25 m / s.

After stopping the stirrer, a sample was taken for COD and BOD ₅ control determinations.

COD .................. 13.8 mg / l

BOD ............. 4.2 mg / l

Oakmile was sampled for control, the contents of vessel A were transferred to a gas tight vessel, the vessel sealed and allowed to stand at 20 ° C. Another water sample taken after 3 days showed the following values:

COD .................. 12.9 mg / l

BOD ₅ .................. 3.2 mg / l

The disintegrated mixture of sludge and ash was left in a closed vessel for 60 days, and was monitored by manometer * for gas evolution. Since no gas evolution was observed during this period, the experiment was terminated.

The water above the sedimented ash was clear, odorless and showed the following COD and BODg values:

COD ................. 12.9 mg / l

BSKg ................. 3.2 mg / l

The contents of vessel B were stirred on the mixer for 30 min, again at a stirrer speed of 1.25 m / s. After the stirrer was stopped, a sample of water was taken for COD and BODg determination.

<* »

In this case:

COD .......... »...... 18.9 mg / l

BOD ................. 12.0 mg / l

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The mixed mixture was transferred, as in case A, to a gas-tight container in which it was left at 20 ° C for 60 days. Manometric monitoring showed gas evolution starting on day 3. Due to the fact that gas development stopped after about 58 days, the experiment was stopped on day 60. The water sample taken over the sedimented ash matter smelled slightly rotting and cloudy. The following values were found during the analytical check:

COD .......... 18.2 mg / l

BSI < ₅ ................ 10.3 mg / L

The experiment showed that using the process of the invention (vessel A) reduced BOD ₅ by 74.7 while the original process (vessel B) reduced BOD ₅ by only 14.17%,

Example 2

The experiment in Example 1 was repeated under the same conditions, except that the ratio of the sludge from the primary sedimentation, flotation and biological sludge to the mixture of heating ashes and damage was 18.5 mg sludge per 1 g of ash.

The resulting chemical oxygen demand (COD) of this mixture was 112 mg / l, the biochemical oxygen demand over 5 days (BODg) was 54.2 mg / l

The contents of vessel A were transferred to a mixer in which mixture 7 was disintegrated at Re, 1, 10. In the next step, the mixture was stirred for 30 minutes on a mixer at the peripheral speed of the mixer

1.4 m / s. After stopping the stirrer, a sample was taken for COD and BOD control.

COD ................. 17.6 mg / l

BSI < ₅ ................. 7.3 mg / L

Oakmile was sampled for control, the contents of vessel A were transferred to a gas tight vessel, the vessel sealed, and allowed to stand at 20 ° C. Another water sample taken after 3 days showed the following values:

COD ................. 13.4 mg / l

BSI < ₅ ................. 4.1 mg / l

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The disintegrated mixture of sludge and ash (sample A) was kept in a closed vessel for 60 days, followed by manometric methods for gas evolution,

Since no gas evolution was observed during this period, the experiment was terminated.

The water above the sedimented ash was clear, odorless and showed the following COD and BOD values.

COD .................. 13.0 mg / l

BSI < ₅ .................. 3.8 mg / l

The contents of vessel B were mixed on the mixer for 30 minutes, again at a peripheral speed of the mixer of 1.4 m / s. After stopping the stirrer, a sample of water was taken to determine COD and BODg,

COD ................. 98 mg / l

BOD ............... 53.8 mg / l

The mixed mixture was transferred, as in the case of Aperture, into a gas-tight container, which was left at 20 ° C for 60 days. Manometric monitoring revealed that, starting on the third day, there was a rapid evolution of gas. After 60 days, when the experiment was completed, the water sample taken over the sedimented ash matter smelled rotting and was cloudy. During the analytical check the following values were found

COD ................... 46.8 mg / l

BSl < ₅ ................... 28.5 mg / l

The experiment showed that using the process according to the invention (vessel A) reduced BODg by 93¾. whereas according to the original procedure (vessel B) to reduce the BSI < _{5 by} only 47.03

Example 3

The suction tank comes from two heating plants and a pressure gas plant, as well as waste sludge from coal treatment, waste water from gasification of the black oil and waste brine. This tank also comes

- 6 241 619 biological sludge from sewage treatment plants, flotation sludge and sedimentation sludge sludges. This mixture, at a solid-to-liquid ratio of 1: 17 to 1: 22, a ratio of 5.2 to 9.6 mg of sludge per gram of ash and COD in the range of 70-95 mg / l, is conveyed by pumps through two pipes.

Js 500 to an ash dump of approximately 300,000 m.

A static mixer was placed in one of the two ducts (A) to achieve Re _f1 1. 10. The second pipe (B) remained in its original condition. After equalizing the flow ratios between lines A and B, it was found that the mixture collected in the manifold, approximately 3,000 m from the pumping station from line A, had a COD of 15.4 - 17.3 mg / l, while the same mixture was collected. from pipe B, it has a COD in the range of 64 - 77 mg / l. Furthermore, it was found that the sample taken from line A left at room temperature (20 ° C) showed no evolution of gas and after 4 days the COD of the water above the ash has dropped to 12.7 mg / l.

In contrast, the same mixture taken from line B under the same conditions showed COD of 58 mg / l (water over ash) after 4 days. In addition, the development of gas bubbles was observed in this sample starting on the second day.

Claims (2)

SUBJECT OF THE INVENTION Λ A process for the disposal of sludge resulting from a waste water treatment process, in particular primary sludge, i.e. raw sludge resulting from settling from water, and biological sludge, characterized in that the biological sludge together with the primary sludge are mixed with solid incineration waste and / or gasification of fossil fuels at a ratio of 3.5 to 18.5 mg / g, preferably 5.1 to 9.6 mg / g, after which the primary and biological sludges in the mixture with the solid waste are mechanically destroyed! by stirring, preferably in an environment of water used for the hydraulic transport of the ashes at a Reynolde number for stirring R &lt; 1. 10 to 1. 10, preferably 1. 10 ⁵ to 1. 10®, whereupon the mixture is said to settle, where the organic matter residues in the water are aerobically purified with oxygen contained in the water. Method according to claim 1, characterized in that the ratio of water used for the hydraulic transport of the ash to the solid phase is 1: 15 to 1: 25, preferably 1: 20.