الفلوكات المستخدمة للترسيب والتجفيف/Flocculant Applications For Precipitation And Dewatering

Flocculant Applications
For Precipitation And Dewatering

technolab el-bahaa group

general.dr

bahaa badr

I. INTRODUCTION

Precipitants, coagulants and flocculants are used in waste treatment to separate unwanted components from water and sludge.

Not only do these materials make the task easier, in some cases the separation would be impossible without them.

This page is divided up into three sections.

The first section

deals with inorganic coagulants and treatment chemicals.

It presents the products that are available, how they are typically used and any pertinent factors relating to their use.

The second section

covers water soluble wastewater treatment polymers. Here, too, we will look at the various products that are used, how they are applied and the various factors which determine their success in waste treatment.

The third section

will look at some of the typical waste treatment applications that you are likely to encounter in the field.

In this section you will see how the inorganics and polymers discussed in the first section are put to use.

Before we get started, let's look at some of the terms and concepts that we will encounter when we are doing waste treatment:

Coagulation -

Coagulation refers to the destabilization of suspended colloidal materials.

Because these particles all carry the same surface charge (usually negative), their mutual repulsion is enough to prevent them from settling.

Note that this is different from precipitation. Also, note that this is technically different from flocculation although the two terms are often used synonymously.

Flocculation -

Flocculation refers to the bridging between particles by a polymer chain, causing them to form flocs or larger aggregates.

These flocs float (flotation) or sink (sedimentation), making them easier to remove from the system.

Precipitation -

Precipitation is the insolubilization of dissolved materials.

An example is the precipitation of iron by raising the pH to 8 with sodium hydroxide to form an insoluble iron hydroxide precipitate.

Sludge Dewatering -

Sludge dewatering is the removal of water from sludge to reduce its volume, lowering hauling costs.

This process, typically accomplished with belt filter or screw presses or other equipment, also makes the sludge easier to burn, reducing fuel costs.

Clarifiers -

Clarifiers are large cylindrical or rectangular basins which allow the separated solids to settle from the water, permitting clear water to pass over a weir.

Dissolved Air Flotation (DAF) -

DAF is the process of passing dissolved air through flocculated wastewater.

The tiny bubbles attach to the flocs, floating them to the surface.

The resulting raft is then skimmed from the top of the water, allowing the clear water to exit the system.

Electrolytes -

Electrolytes are atoms and molecules that, when dissolved in water, ionize and carry a positive (cationic) or negative (anionic) charge.

Ferric chloride and aluminum sulfate are examples.

Polyelectrolytes -

Polyelectrolytes are electrolytes which have more than one charge-bearing atom in the molecule.

Examples are acrylamide copolymers and polyaluminum chloride.

Jar Testing -

Jar testing is the process of evaluating various treatments in the laboratory to determine the best method.

Often a four or six paddle "gang-stirrer" is used to view several treatments simultaneously.

» توريد الواح اللاميلا المستخدمة للترسيب الطبيعى فى معالجة الصرف الصناعى
» البوليمرات المستخدمة كمجلطات وفلوكات ومروقات لمعالجة الصرف الصناعى/Polymers for Coagulation, Flocculation and Dewatering of Solids and Sludge
» FLOCCULANTSانواع الفلوكات
» الفلوكات وانواعها
» طرق تعيين جرعات المجلطات والفلوكات/Coagulation and Flocculation Tests