DE202007019512U1 - Device for reducing odor nuisance in waste water - Google Patents

Abstract

A device for reducing odor in sewage characterized by at least two located on a sewer line sampling points through which the sample passes into a measuring device for the hydrogen sulfide or sulfide concentration, and at least one supply line into the sewer line for the wastewater treatment agent, which is connected to a metering device , And a particular controlled by the signals emanating from the measuring signals computer for dosing wastewater treatment agents.

Description

The present invention relates to a device for reducing odor nuisance in wastewaters.

Among the odor-causing substances in wastewater, H ₂ S is the most toxic and, because of its low odor threshold, the most unpleasant. It is caused by anaerobic decay processes and at the same time it is a marker for a deficit of oxidants, especially oxygen. To reduce the odor nuisance, therefore, oxygen, nitrate or other oxidizing agents are added to the waste water, or the sulfide is precipitated by metal ions.

Various methods and devices have been described in the literature for automating the difficult analytical detection of H ₂ S in wastewater and providing a quasi-continuous signal that can be used as a guide to dosing an odor control agent.

So will in the DE 10 2005 060 193 A1 proposed to record the degree of contamination of the wastewater analytically and to use as a control variable for the dosage of odor reducing agents.

However, the relationship between sulfide content and necessary dosage is complex and depends on temperature, pH, microbial population and other factors, so the relationship between sulfide value and dose of the water treatment agent must be empirically determined and can not be considered constant.

In many cases, an overdose occurs in order to compensate for deficits in the determination of the rate of formation of odorous substances, which, however, leads to increased costs for the odor control agent and may cause undesirable side reactions.

In order to avoid an overdose of nitrate - containing wastewater treatment agents WO 03/086986 the sewer is subdivided into sections, each equipped with a H ₂ S measuring device and a metering device for nitrate-containing chemicals. In this case, an underdosing is detected in the respective next section and it can be replenished accordingly. However, there is an increased effort for the additional metering and conveying technology in the individual sections.

A precise, exact dosage of wastewater treatment chemicals can not be realized so far.

The present invention is based on the problem of developing a device which makes it possible to optimize the amount of treatment agents required to reduce the hydrogen sulfide content of waste water.

This problem is solved according to the claims by a device having the features of claim 1. Further developments will become apparent from the dependent claims.

At least two measuring points, which are located on a sewer, are used to determine the guiding parameter hydrogen sulfide in the gas and / or liquid phase of a sewer line by means of hydrogen sulfide and / or sulfide analyzers.

The measured values obtained are fed to a control computer, which calculates the required addition amount of wastewater treatment agents, such as oxidants, precipitants or biocidal substances, and controls the dosing pumps for the wastewater treatment agent. The regulation of the dosage of the wastewater treatment agent is carried out by the use of the measured values, which are obtained from the simultaneous determination of the hydrogen sulfide or sulfide concentrations at least two measuring points, preferably at the entrance and exit of sewers. The measured values obtained at the inlet provide the basic concentration of hydrogen sulfide or sulfide ions and in correlation with the value at the outlet, the possible hydrogen sulfide formation is determined. With both measured values dosing profiles are created, which allow an optimal use of the treatment agents. It is also possible to use a measurement, which is determined at a further measuring point after the addition of the treatment agent, for regulation.

The metered amount of treatment agent is modulated by a slowly adjusted base value and the variations of the hydrogen sulfide value caused by this modulation are analyzed, the modulation of the metered quantity by means of a periodic function, preferably a triangular or sawtooth function, and the evaluation by assignment of the measured values takes place to the metered amount.

With the help of hydrogen sulfide sensors either directly outgassed from the wastewater or extracted from a wastewater sample hydrogen sulfide are detected continuously or quasi-continuously.

The gas phase detection of H ₂ S is very selective by the gas sample continuously and with defined flow conditions the detector is supplied. Through integrated calibration functions, the analysis result is either related to the gas phase of the wastewater system, to the gas phase extracted from the wastewater or directly to the wastewater.

The required amount of treating agent is determined by titrating the waste water with the treating agent using the treating agent as the titrator and using the H ₂ S concentration as an indicator.

The analyzes of the gas phase of the sewage system and / or the liquid phase with downstream gas extraction step take place after mixing with the wastewater treatment agent in the gas analyzer. In both cases, it is important that the detection system be rinsed. The detection system is preferably supplied with fresh air, the sampling system flushed with water.

For direct analysis of the liquid phase, a sulfide analyzer can also be used.

To increase the reliability of measurement, the decoupling of the sampling system from the detector is advantageous. This is also beneficial if in the room in which the sampling takes place, risk of explosion is possible.

embodiments

The invention will be explained in more detail in five figures and examples. Show it:

1 a scheme for itself at a sewer pipe in the flow direction between two sampling points for the measuring points located supply line with metering device for the wastewater treatment agent

2 : a scheme for itself at a sewer pipe in the flow direction between two sampling points for the measuring points located supply line with metering device for the wastewater treatment agent and another sampling point in the flow direction

3 : a scheme for itself at a sewer pipe in the flow direction between two sampling points for the measuring points located supply line with metering device for the wastewater treatment agent and another sampling point in the flow direction

4 A device for detecting the H ₂ S formation potential by detecting the H ₂ S content at the entrance and exit of a sewer

5 : the acquisition and correlation of H ₂ S measurement data at the inlet and outlet of a pressurized water pipeline

Example 1:

According to 1 is via the control computer ( 5 ) the dosage of the water treatment agent ( 6 ), z. B. of iron salts, continuously increased and lowered again after reaching a maximum value again. The answer function to measuring point ( 3 ) is based on the flow rate of the time of dosing and determines the necessary amount of water treatment agent. In order to be able to react to rapid changes in demand, the measured value at the measuring point ( 4 ) and takes into account the new formation rate in the pipe system obtained from previous measurements.

Example 2:

According to 2 is via the control computer ( 5 ) by means of metering pump ( 6 ) continuously increased amount of water treatment agent until the H ₂ S content at measuring point ( 2 ) falls below a minimum threshold. This is done taking into account the flow rate of the waste water, so that always a defined ratio of the two volume flows can be set. The H ₂ S content at the measuring point ( 3 ) is calculated taking into account the calculated from the flow rate runtime with the H ₂ S content at measuring point ( 2 ) and thus determines the rate of regeneration during transport in the tube. To compensate for the H ₂ S regeneration, an additional amount of water treatment agent via the metering pump ( 6 ), whose quantity from the response function of the measuring point ( 2 ) due to the modulation of the dosing amount of the pump ( 6 ) is calculated. After a training phase, at which 3 ) even larger amounts of H ₂ S should occur, the necessary overdose of water treatment agent from the on the interaction between dosing ratio and response of the measuring point ( 2 ) obtained data from the measurement signal of the measuring point ( 4 ) and corrected according to temperature and flow.

Example 3:

According to 3 is via the control computer ( 5 ) by means of metering pump ( 6 ) continuously increased amount of water treatment agent until the H ₂ S content at measuring point ( 2 ) falls below a minimum threshold. This is done taking into account the flow rate of the waste water, so that always a defined ratio of the two volume flows can be set. The H ₂ S content at the measuring point ( 3 ) is calculated taking into account the calculated from the flow rate runtime with the H ₂ S content at measuring point ( 2 ) and thus determines the rate of regeneration during transport in the tube. The amount of water treatment agent that corresponds to the rate of regeneration is controlled by the dosing pump ( 7 ), taking into account the trend seen from the time course.

The rate of water treatment agent to be metered is determined by modulating the amount of metering pump ( 6 ) and evaluation of the signal at the measuring point ( 2 ) periodically determined, the effect of this modulation on the H ₂ S content in the pipeline by pump ( 7 ) is compensated again. With this arrangement, both the current value and the H ₂ S new formation can be detected.

Example 4

According to 4 H ₂ S detectors at the measuring point ( 3 ) and measuring point ( 4 ) of the sewer ( 1 ) fixed. According to the residence time in the line is a simultaneous data recording. Depending on local circumstances, the sample gas obtained in the analyzer either directly or by mixing after mixing a defined volume of the sample with a reagent, eg. B. 2 mol / l HCl solution, the H ₂ S gas is released and analyzed. In 4 is the application of a H ₂ S analyzer for H ₂ S determination in the water phase at the measuring point ( 4 ) and for H ₂ S determination in the gas phase at the measuring point ( 3 ) of the sewer ( 1 ).

For H ₂ S determination in the gas phase, the sample gas above the waste water of the sewer ( 1 ) by the gas sampling line ( 8th ) by means of the gas sampling pump ( 11 ) by the H ₂ S detector ( 10 ) and then via the sample return ( 9 ) led back into the sewer. The detector provides a continuous measurement signal in this mode of operation, while allowing a continuous purge with sample gas.

If a discontinuous measurement of the gas sample at defined times is intended, then by turning the two three-way valves ( 12 ) between the measurements fresh ambient air ( 13 ), which has optionally been cleaned via a filter cartridge, are fed, whereby a longer life of the detectors is achieved. After rinsing the detector until a stable baseline is reached, both three-way valves ( 12 ) is switched into the sample position and fresh sample gas is flushed through until a stable measuring signal is achieved.

If defined conditions exist with regard to the gas conduction in the sewer or in the corresponding building, so that a stable equilibrium between gas phase and water phase is established, the H ₂ S detector ( 10 ) without gas sampling pump ( 11 ) and without gas sampling line ( 8th ) and without sample recycling ( 9 ) operate.

For H ₂ S determination in the water phase, the wastewater is removed via the water sampling line ( 15 ) by means of a pump for the water sample ( 16 ) through the gas extraction chamber ( 17 ) and then via the sample return ( 9 ) led back into the sewer. Simultaneously, the supernatant gas from the gas extraction chamber ( 17 ) by means of the gas sampling pump ( 11 ) by the H ₂ S detector ( 10 ) and via the gas outlet ( 14 ) dissipated. The detector provides a continuous measurement signal in this mode of operation, while allowing a continuous flushing with the water sample.

If a discontinuous measurement of the water sample at defined times is intended, then by rotating the two three-way valves ( 12 ) between the measurements constantly with fresh ambient air, which was optionally cleaned via a filter cartridge, be rinsed, whereby a longer life of the detectors is achieved. At the same time, the three-way valve ( 21 ) and the gas extraction chamber ( 17 ) with H ₂ S-free rinse water ( 20 ). After rinsing the detector until a stable baseline is reached, both three-way valves ( 12 ) into the sample position for gas passage through the gas extraction chamber ( 17 ). Via the three-way valve ( 21 ) fresh water sample is flushed through until a stable measurement signal is achieved. Allows the gas velocity of the gas sampling pump ( 11 ) for flushing the gas extraction chamber ( 17 ), a shorter rinsing time than with the pump for the water sample ( 16 ) can be achieved for rinsing the water sample, in the rinsing step on the direct gas path connection between the three-way valves ( 12 ) are waived. The rate-limiting step in this case is to achieve a constant H ₂ S signal in the gas extraction chamber due to the filling with the current wastewater sample.

Both obtained H ₂ S measurement signals at the measuring point ( 3 ) and measuring point ( 4 ) of the sewer are controlled by the control computer ( 5 ) synchronized taking into account the flow rate and temperature of the waste water and provide the evidence for H ₂ S formation potential and thus for the multi-dose of the treatment agent.

Example 5

5 shows a comparison of H ₂ S measurement data of input and output of a sewer. If a significant H ₂ S concentration is detected at the entrance to the sewer, it can be assumed that H ₂ S will increasingly form during the residence time in the sewer, which will ultimately lead to odor nuisance. When using the H ₂ S detectors, it must be ensured that H ₂ S analyzes with high detection sensitivity, preferably in the range between 0.005 to 10 mg / l wastewater, are possible at the entrance to the sewer. Depending on the nature of the sewer pipe (eg length, residence time, concentration of the organic components), concentrations of up to 200 ppm H ₂ S relative to the gas phase can be expected at the outlet of the sewer pipe.

LIST OF REFERENCE NUMBERS

1

sewer

2

H ₂ S measuring point

3

H ₂ S measuring point

4

H ₂ S measuring point

5

tax calculator

6

Dosing pump for wastewater treatment agent

7

Dosing pump for wastewater treatment agent

8th

Gas sampling line

9

Sample return

10

H ₂ S detector

11

Gas sampling pump

12

Three-way valve

13

Supply of ambient air

14

gas output

15

Water sampling line

16

Pump for the water sample

17

Gas extraction chamber

18

reagent addition

19

Reagent

20

dishwater

21

Three-way valve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005060193 A1 [0004]
• WO 03/086986 [0007]

Claims (6)

A device for reducing odor in sewage characterized by at least two located on a sewer line sampling points through which the sample passes into a measuring device for the hydrogen sulfide or sulfide concentration, and at least one supply line into the sewer line for the wastewater treatment agent, which is connected to a metering device , And a particular controlled by the signals emanating from the measuring signals computer for dosing wastewater treatment agents. Apparatus according to claim 1, characterized in that in the flow direction of the waste water, the supply line for the wastewater treatment agent is located between two sampling points. Apparatus according to claim 1 and 2, characterized in that there is another sampling point in the flow direction. Apparatus according to claim 1 to 3, characterized in that there is an additional supply line for the wastewater treatment agent in the flow direction before the first sampling point. Apparatus according to claim 1 to 4, characterized by analyzers with a self-cleaning detection system for the continuous and / or discontinuous determination of the hydrogen sulfide concentration in the sample gas taken. Apparatus according to claim 1 to 4, characterized by analyzers for continuous and / or discontinuous determination of the sulfide concentration in the withdrawn liquid phase.

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