DE102006050921B3 - Method and device for sewage sludge conditioning - Google Patents

Abstract

The sludge is mixed with flocculant then separated into de-watered sludge and filtrate water. The filtrate water flows through and is irradiated in, a measurement sensor (8). Reflection signals from the filtrate water are recorded. Should the reflectivity depart from a given value, the quantity of flocculant supplied is raised or lowered. The reflection signal is measured continuously. A motorized mixer introduces the flocculant. On reflectivity departures, its speed is raised or lowered. Raising or lowering the quantity of flocculant or the motor speed, is effected in steps. Irradiation takes place in the visible wavelengths. The equipment used, includes a feed vessel (2) and a de-watering unit (4), i.e. a centrifuge. The measurement system (6) includes the sensor for reflectivity measurement. A controller (14) makes corresponding adjustments. The optical transmitter and receiver include optical fibers. An independent claim IS INCLUDED FOR the equipment used.

Description

The This invention relates to a method and apparatus for sewage sludge conditioning.

Around sewage sludge machine drain to be able to conditioning must be carried out in advance. This is done by means of a Flocculant (FHM). Be under flocculation aids For example, treated synthetic organic polyelectrolytes understood, which are used to the processes of a solid / liquid separation technically and economically. When using flocculants It is the endeavor of plant operators to make these products economical use. Under ecological Aspects (eg use of dewatered sludge in agriculture) and for the economic Product use will therefore be for treatment plant operators increasingly important to optimize the use of flocculants and automate to recover as quickly as possible in all occurring fluctuations to achieve an optimal and stable operating condition. A possibility This optimization is the automation of flocculant dosage. This automation takes place today mainly as so-called Freight-related flocculation aid dosage.

The effectiveness and the associated needed Amount of flocculant in a solid / liquid separation is determined by the Composition of the respective waste water and specific wastewater parameters determines, to which charge, size and size distribution the solids as well as the electrolyte content and the organic components of suspensions as well as temperature and pH. For a freight-related Flocculant dosage is the amount of flocculant additive added in the fixed predetermined ratio to the dry matter content of the feed sludge determined. in this connection is usually dosed in more than needed, for any changes to be considered in the mud and a clean filtrate and on the other a stable operation to reach the centrifuge plant.

From the DE 101 15 179 A1 a method and a measuring arrangement is known, which is based on a one-dimensional incident light measurement without preceding degassing for detecting the flake structure and subsequent determination of chord lengths and / or run lengths from the gray scale gradients. From a determined frequency distribution, a concentration factor is subsequently determined.

Both from the DE 44 37 062 A1 as well as from the DE 38 72 838 T2 Methods and apparatuses for controlling or regulating a solid-liquid separation process are known, which use screen belt presses or screen belt thickeners as dewatering machines. On the sieve belt drained with flocculants and drained sludge drains. This process is monitored by means of a measurement based on the evaluation of surface reflection signals of the sludge being dewatered on the screen belt.

The The object of the invention is a comparison with the state of the simpler To provide a method and a simpler device that a more accurate Allow flocculant dosage.

• – Mischen von zu entwässerndem Schlamm mit einem Flockungshilfsmittel,
• – Trennen des mit Flockungshilfsmitteln versehenen Schlamms in entwässerten Schlamm und Filtratwasser.

The object is achieved by a method having the steps of patent claim 1. The method according to the invention is based on a process for sewage sludge conditioning with the following steps:

• Mixing sludge to be dewatered with a flocculant,
• - Separating the flocculants provided with sludge in dewatered sludge and filtrate water.

• – in einer durchströmten Messsonde Filtratwasser bestrahlt wird,
• – Reflexionssignale vom Filtratwasser erfasst werden, und
• – auf ein Abweichen von einem vorgegebenen Reflexionswert hin ein Erhöhen oder Erniedrigen der zugeführten Menge an Flockungshilfsmitteln erfolgt.

The inventive method is characterized in that

• - filtrate water is irradiated in a flow-through measuring probe,
• - Reflection signals are detected by the filtrate, and
• - If there is a deviation from a given reflection value, an increase or decrease in the amount of flocculation aids added takes place.

By a simple reflection measurement and detection of a simple sum parameter it is surprising easy way possible meaningful To obtain measured values that provide a reliable control of flocculant addition allow. The new procedure allows with the measuring probe and a controller system a dynamic control, d. H. through the surveillance of the filtrate water can be an exact quantity metering according to the actual Requirement and change can be reacted immediately. As a result, less flocculants needed and a more stable operation with less operating effort of the centrifuge system is achieved.

Of the Solids content can be z. B. determined at fixed time intervals become. Preferably, however, it is provided that the reflection signals be recorded continuously.

In a preferred embodiment of the method according to the invention, it is provided that the mixing takes place with a motor mixer, wherein, on a deviation from a predetermined reflection value, increasing or decreasing the rotational speed of the engine mixer. In this way, the respective required mixing energy can be optimized with changing properties of the sludge and the consumption of flocculants can be reduced.

The Adjustment of the supplied Amount of flocculants or the speed of the motor mixer can be done continuously, here, for example, a PID controller or an adaptive controller can be used. However, it is preferable provided that increasing or lowering the supplied Amount of flocculants and / or the speed of the motor mixer be done gradually so that only a single controller is needed, which can be realized, for example, with a PLC control. alternative You can also use a fuzzy logic controller.

Preferably is provided that the filtrate water with light in the visible wavelength range is irradiated. So can known light sources such. As LEDs are used. It can be light with a wavelength or with a spectrum of wavelengths. Prefers becomes white Light with a uniform spectrum used. However, it is also conceivable to use colored light or light, its wavelength range in the invisible area, such as As infrared or UV light.

The Device for controlling the addition of flocculant aid a flocculant auxiliary reservoir and a drainage device, wherein from the flocculant auxiliary reservoir or the storage container flocculants to be drained Mud fed can be and the drainage device for the separation of flocculants with sludge in dehydrated Mud and filtrate water is formed.

The inventive device is characterized in that a measuring device at least a flowed through during operation Measuring probe, irradiated in the flowing filtrate water is, wherein the measuring probe is designed for reflection measurement and a control device is provided, wherein the control device is formed such that a deviation from a predetermined Reflectance value supplied Amount of flocculant can be increased or decreased.

Consequently allows the device according to the invention a reliable one and accurate monitoring and thus an optimal dosage of the amount of flocculants added.

there it is preferably provided that the dewatering device a centrifuge having. It can but instead of a centrifuge, other drainage facilities be used, for example, presses or decanters.

Further It is preferably provided that a motor mixer for mixing the to drain Sludge is provided with the flocculant, wherein the Control device is designed such that a departure from a predetermined solids content, the speed of the motor mixer elevated or can be lowered and so the respective required mixing energy at changing Characteristics of the sludge optimized and the consumption of flocculants is reduced.

Preferably it is provided that the measuring probe has a transmitter and a receiver, so that the probe housed as a compact unit in a housing can be and at the same time splash-proofed.

In a preferred embodiment is provided that the transmitter for emitting light in the visible Wavelength range and the receiver for receiving reflected light in the visible wavelength range is trained.

there It is preferably provided that the transmitter and the receiver are optical fibers exhibit. The optical fibers make a connection between Sender and receiver and thus allow an arrangement of the housing in a suitable location.

It The invention will now be explained with reference to a drawing. It demonstrate:

1 a schematic representation of a first embodiment of a device according to the invention,

2 a schematic representation of a second embodiment of a device according to the invention with a motor mixer, and

3 a sectional view of an embodiment of a measuring probe.

It will be initially on the 1 and 2 Referenced.

The wastewater treatment apparatus, which may be part of a multi-stage wastewater treatment plant, comprises a sump 20 in which sludge to be dewatered can be collected and thus, in particular, fluctuations of the feed quantity can be compensated. A first line 22 connects to one as a centri fuge trained drainage facility 4 ago, with a pump 24 for the promotion of the sludge to be drained.

A container 2 for flocculation aids has a conveyor 28 on, with the over a second line 30 Flocculants at a junction 32 in the first line 22 can be promoted, where the flocculants mix with the sludge to be drained and the drainage device 4 be supplied.

The trained as a centrifuge dewatering device 4 separates the sludge provided with the flocculation aids in dewatered sludge, which is placed in a container 34 is collected and in filtrate water 59 passing through a filtrate water pipe 36 the further wastewater treatment of a multi-stage sewage treatment plant can be supplied.

At the Filtratwasserleitung 36 is a measuring channel 38 connected, with a part of the filtrate water 59 a measuring device 6 can be supplied to determine the solids content. The measuring device has a measuring probe 8th referred to below with reference to 3 is explained.

The by means of the measuring device 6 The measured value determined is via a measuring line 40 a control device 14 supplied, which has, for example, a PLC control and is designed in such a program that continuously or in fixed, predeterminable time intervals, a comparison with a predefinable reflection value takes place and increases to a deviation from the predetermined reflection value, the supplied amounts of flocculants in likewise predeterminable steps or is lowered. For this purpose, a first control line 42 a connection from the control device 14 with the conveyor 28 ago, by means of the conveyor 28 can be controlled.

This in 2 illustrated second embodiment has at the junction 32 in contrast to the first embodiment, a motor mixer 12 on, which causes an improved mixing of the flocculants with the sludge to be drained. This is a second control line 44 a connection to the control device 14 so that the control device 14 is additionally designed program-wise such that the speed of the motor mixer to a deviation from the predetermined Refflexionswert 12 increased or decreased.

In both embodiments, the control device 14 be designed self-diagnostic capable, so malfunctions of the probe 8th to capture, for example by a plausibility check of measured values.

It will now be on the 3 Referenced.

The measuring probe 8th is formed from a cylindrical body formed in the present embodiment basic body 50 , which is made of a permeable to light in the visible wavelength range material, such as plexiglass. Through the interior of the body 50 during operation filtrate water flows.

In a housing 52 are a transmitter 46 and a receiver 48 arranged, the transmitter 46 is designed for emitting light with wavelengths in the visible range and has, for example, an LED or other suitable source for this purpose. Analog is the receiver 48 designed to receive reflected light whose wavelengths are also in the visible range. For this purpose, the receiver 48 a photodiode, a phototransistor or another suitable component.

The transmitter 46 and the receiver 48 are ever with a light guide 56 . 58 connected, the connections to the body 50 make and allow light from the transmitter 46 on through the interior of the main body 50 flowing filtrate water 59 to judge and analog reflection signals or of flowing filtrate 59 reflected light to the receiver 48 to conduct, so as to allow a reflection measurement.

2

reservoir

4

dehydrator

6

measuring device

8th

probe

12

engine mixer

14

control device

20

Clippings

22

first management

24

first pump

28

Conveyor

30

second management

32

junction

34

Container

36

Filtratwasserleitung

38

measuring channel

40

Measurement line

42

first control line

44

second control line

46

transmitter

48

receiver

50

body

52

casing

54

Return line

56

optical fiber

58

optical fiber

59

filtrate water

Claims (11)

Sludge conditioning process comprising the steps of: - mixing sludge to be dewatered with a flocculant, - separating the flocculation aid sludge into dewatered sludge and filtrate water ( 59 ), characterized in that - in a flow-through measuring probe ( 8th ) Filtrate water ( 59 ) is irradiated, - reflection signals from the filtrate water ( 59 ), and - if a deviation from a given reflection value deviates, the amount of flocculation aids supplied is increased or decreased. Method according to claim 1, characterized in that that the reflection signals are detected continuously. Method according to claim 1 or 2, characterized in that mixing with a motor mixer ( 12 ), wherein upon a deviation from a predetermined reflection value, increasing or decreasing the rotational speed of the engine mixer ( 12 ) he follows. Method according to one of claims 1 to 3, characterized in that the increasing or decreasing the amount of flocculants and / or the speed of the motor mixer ( 12 ) progressively. Method according to one of the preceding claims, characterized in that the filtrate ( 59 ) is irradiated with light in the visible wavelength range. Sewage sludge conditioning device comprising a storage container ( 2 ) and a drainage device ( 4 ), whereby from the reservoir ( 2 ) Flocculant can be supplied to the sludge to be drained and the drainage device ( 4 ) for the separation of flocculants with sludge in dewatered sludge and filtrate water ( 59 ), characterized in that a measuring device ( 6 ) at least one measuring probe through which flow passes during operation ( 8th ), in which filtrate water flowing through is irradiated, wherein the measuring probe ( 8th ) is designed for reflection measurement and a control device ( 14 ), the control device ( 14 ) is designed such that, on a deviation from a predetermined reflection value, the supplied amount of flocculant can be increased or decreased. Apparatus according to claim 6, characterized in that the drainage device ( 4 ) has a centrifuge. Apparatus according to claim 6 or 7, characterized in that a motor mixer ( 12 ) is provided for mixing the sludge to be drained with the flocculation aid, wherein the control device ( 14 ) is designed such that, for a deviation from a predetermined solids content, the speed of the engine mixer ( 12 ) can be increased or decreased. Device according to one of claims 6 to 8, characterized in that the measuring probe ( 8th ) a transmitter ( 46 ) and a receiver ( 48 ) having. Device according to claim 9, characterized in that the transmitter ( 46 ) for emitting light in the visible wavelength range and the receiver ( 48 ) is adapted to receive reflected light in the visible wavelength range. Device according to one of claims 6 to 10, characterized in that the transmitter ( 46 ) and the recipient ( 48 ) Optical fiber ( 56 . 58 ) exhibit.