DD254730A1

DD254730A1 - DEVICE FOR DEHUMIDIFYING WASTEWATER SLUDGE

Info

Publication number: DD254730A1
Application number: DD29772786A
Authority: DD
Inventors: Guenter Ostermann; Kristian Marten
Original assignee: Wasserversorgung Abwasse
Priority date: 1986-12-17
Filing date: 1986-12-17
Publication date: 1988-03-09

Abstract

Die Erfindung betrifft die maschinelle Entwaesserung von Schlamm aus Abwasserklaeranlagen unter Verwendung von polymeren Flockungsmitteln. Ziel der Erfindung ist es, mit geringem Ausruestungs- und Energieaufwand eine betriebssichere und kontinuierliche Schlammentwaesserung bei geringem Flockungsmitteleinsatz zu erreichen. Die Aufgabe wird durch eine Einrichtung, bestehend aus einer Mischeinrichtung fuer Schlamm und Flockungsmittel mit anschliessender Flockenstabilisierungsrinne und danach angeordneter Siebtrommel geloest. Erfindungsgemaess wird der mit Flockungsmittel durchmischte Schlamm in eine Rinne mit mindestens 4 Flockungskammern geleitet, in der sich stabile Schlammflocken bilden. In der anschliessenden Siebtrommel mit grosser Maschenweite fliesst das Schlammwasser schnell ab und es bildet sich eine entwaesserte Schlammrolle, die zwischengelagert oder abgefahren werden kann. Die Schlammrolle entwaessert bei Zwischenlagerung nach, nimmt aber keine Feuchtigkeit mehr auf. Der spezifische Flockungsmittelbedarf kann gegenueber Zentrifugen um 20...50% verringert werden. Es tritt kein mechanischer Verschleiss bei der Schlammentwaesserung auf. Fig. 1The invention relates to the machine dewatering of sludge from sewage plants using polymeric flocculants. The aim of the invention is to achieve a reliable and continuous Schlammentwaesserung with low flocculant use with little equipment and energy expenditure. The object is achieved by a device consisting of a mixing device for sludge and flocculants with subsequent flake stabilization channel and then arranged sieve drum. According to the invention, the sludge mixed with flocculant is passed into a channel with at least 4 flocculation chambers in which stable sludge flocs are formed. In the subsequent sieve drum with a large mesh size, the sludge water flows quickly and it forms a dewatered sludge roll, which can be stored or driven off. The sludge roll dewatered during storage, but absorbs no more moisture. The specific flocculant requirement can be reduced by 20 ... 50% compared to centrifuges. There is no mechanical wear on the Schlammentwaesserung. Fig. 1

Description

Schlammwasser wird über eine Auffangrinne abgeleitet. In gröeren Zeitabständen werden restliche Schlammteile aus dem Maschensieb abgespült.Mud water is discharged via a gutter. At longer intervals residual sludge parts are rinsed from the mesh screen.

Die Erfindung wird an einem in den Figuren 1 und 2 dargestellten Ausführungsbeispiel näher erläutert: Der zu entwässernde Abwasserschlamm 11 wird mit dem gelösten Flockungsmittel 12 in dem Mischgefäß 1 intensiv durchmischt. Die Ablenkplatte 2 bewirkt eine Strömungsumlenkung und verhindert eine Kurzschlußströmung zum Gefäßablauf. In der anschließenden Flockenstabilisierungsrinne 3 wird der Schlamm in den Flockungskammem 4 jeweils in Teilströme aufgeteilt und anschließend wieder vermischt. Dieser Flockenstabilisierungseffekt ist von entscheidender Bedeutung für die Entwässerung des Schlammes, da der Schlamm sonst die Sieböffnungen verklebt. Bereits in der vorletzten Kammer trennt sich das Wasser deutlich vom Schlamm. Ein Beispiel ist in Figur 2 dargestellt mit 4 runden Flockungskammem und eingebautem Strömungsteiler 10.The invention will be explained in more detail on an exemplary embodiment illustrated in FIGS. 1 and 2: The sewage sludge 11 to be dewatered is thoroughly mixed with the dissolved flocculant 12 in the mixing vessel 1. The baffle 2 causes a flow deflection and prevents a short circuit flow to the vessel outlet. In the subsequent flake stabilizing channel 3, the sludge in the flocculation chambers 4 is divided into sub-streams and then mixed again. This floc stabilizing effect is of crucial importance for the drainage of the sludge, since the sludge otherwise sticks to the sieve openings. Already in the penultimate chamber, the water separates significantly from the mud. An example is shown in FIG. 2 with four circular flocculation chambers and built-in flow divider 10.

In der anschließenden, langsam rotierenden Siebtrommel 5 in Form eines Innenfilters mit 1 mm Maschenweite ballen sich die Schlammflocken zu einer Schlammrolle zusammen. Das Schlammwasser tritt durch das Sieb durch und wird über die Auffangrinne 8 abgeleitet. Infolge der Achsneigung von etwa 1:10 erfolgt der Austrag der Schlammrolle selbsttätig ohne behindernde Einbauten. Dieser entwässerte Schlamm 9 kann zwischengestapelt oder mittels Gurtbandförderer auf LKW geladen werden. Schlammreste in der Siebtrommel werden intermittierend durch eine äußere Wasserspülung 7 entfernt. In einer halbtechnischen Versuchsanlage wurde mit einer 3 m langen Flockenstabilisierungsrinne und einer 1,2 m langen Siebtrommel bei Zugabe von 5g Separan je kg Schlammfeststoffe ein Durchsatz von über 80 kg/m² h erreicht. Der Energieaufwand war mit 2 kW minimal. Der abgetrennte Schlammkuchen war gut transportfähig und nahm anschließend kein Niederschlagswasser mehr auf. Restliche Schlammflocken im Schlammwasser oder Spülwasser waren gut absetzbar.In the subsequent, slowly rotating sieve drum 5 in the form of an inner filter with 1 mm mesh size, the sludge pellets are combined into a mud roller. The muddy water passes through the sieve and is discharged via the gutter 8. Due to the axial inclination of about 1:10, the discharge of the mud roller is done automatically without obstructing installations. This dewatered sludge 9 can be stacked or loaded onto trucks by belt conveyors. Sludge residues in the sieve drum are removed intermittently by an external water rinse 7. In a pilot plant, a throughput of more than 80 kg / m ² h was achieved with a 3 m long flake stabilizing trough and a 1.2 m long screening drum with the addition of 5 g of separator per kg of sludge solids. The energy consumption was minimal with 2 kW. The separated mud cake was well transportable and then took no more rain water. Remaining mud flakes in the mud or rinse water were well deductible.

Claims

1. A device for continuous drainage of sewage sludge, especially of digested sludge when using polymeric flocculants, characterized in that they from a round mixing vessel (1) with flow baffle plate (2), from a subsequent, strongly inclined flake stabilizing channel (3) with at least 4 rounded Flocculation chambers (4) with flow divider (10) and from a low-pitched and low-speed rotating sieve drum (5) with large mesh size, wherein the sieve drum an inner axial mud entry and discharge and an outer rinsing device (7) and under the sieve drum a Containing gutter (8) for the muddy water.

2. Device according to item 1, characterized in that the rotating screen drum has a diameter of 0.4m to 0.8m, with 1: 5 to 1:20 is inclined in the axis and the mesh size is 0.5 to 2.0 mm ,

3. Device according to item 1, characterized in that the peripheral speed of the screening drum is 0.4 m / s to 2 m / s.

For this 1 page drawings

Field of application of the invention

The invention relates to a device for the continuous dewatering of sludge in wastewater treatment plants

Characteristic of the known state of the art

Devices are known for mechanical sludge dewatering using polymeric flocculants, such as decanter centrifuges with large rotating masses and high wear on solids discharge screws. The investment and operating costs, the failure rate and the repair costs are very high. The use of belt filter presses with different filter and pressing areas and with many deflections for the endless filter belt are known. To form large Schiammflocken also polymeric flocculants are used. The complicated mechanical structure and the many roller drives also require high investment and operating costs and frequent repairs. The mixing of flocculants and sludge takes place in closed pipelines with and without flow diverters and in special containers. Always preclude coarse shredders. There is also the risk of fixing fibrous materials contained in the sewage sludge. Furthermore, vacuum filters and filter presses for machine sludge dewatering have been used. For sludge flocculation, large quantities of iron and aluminum salts and lime are added. The high energy requirement, the precipitant requirement, the strong corrosion and the wear of the filter cloths are significant disadvantages of these devices.

Object of the invention

The aim of the invention is to achieve a reliable, continuous sludge dewatering with low flocculant use with little equipment and energy.

Explanation of the essence of the invention

The invention has for its object to provide a device with the addition of low flocculant so stable mud flakes can be formed that neither high-speed, massive centrifuges or complicated belt filter presses nor expensive vacuum systems or high filter pressures are required for the subsequent dewatering. The mixing device for sludge and flocculant must work without clogging. According to the invention the object is achieved in that an open mixing device for the sewage sludge and the dissolved polymeric flocculant with a subsequent flake stabilizing trough and a simple, slowly rotating sieve drum for the separation of the sludge water is provided. For flow diversion and for better mixing, a baffle plate is arranged in the upstream round mixing vessel. The flake stabilizing trough is strongly inclined and consists of at least 4 sequentially arranged flocculation chambers. The subsequent rotating at low speed screen drum has a large-meshed internal filter and a mounted above the screen drum flushing device.

With this solution, it is possible to intensively mix the dissolved polymeric flocculants and the sewage sludge and to achieve in the downstream flocculation stabilization channel the optimum floc structure determined in our own laboratory experiments. The sewage sludge flocculated until the formation of clear water runnels is then subsequently dewatered in a screen drum while avoiding high shear forces to form a sludge roll. The passage through the sieve