Surfactant and flocculants, influence on drying process / sludge drying, slurry drying, waste drying

Operation process in manufacturing industry generally includes cleaning process. Detergent is one of the substances used in the cleaning process. Detergent always contains surfactant and surfactant helps the cleaning process a lot.

Then, what is surfactant?

Surface
Materials can be classified into three types which are solids, liquids and gases. Boundary where these phases contact is called interface.  There are five patterns of interface as the following. Solid and solid, solid and liquid, solid and gas, liquid and liquid, then liquid and gas.

Activator
Chemical agents or products which exert one’s function and enhance its performance is called activator.

What is surfactant
Surfactant is generic name of chemical agents which exert specific function of interface and enhance its performance. For example, water and oils can hardly be mixed together normally. Water and oil are not mixed originally since interface exists between them, however, surfactant acts on the interface to change its characteristics and water and oils becomes to be able to mix together.

Function of surfactant
1) Emulsification, Break down
Even water and oil cannot be mixed together originally, they can be mixed easily by being stirred after a little amount of surfactant is added, and stable emulsion can be made. This function of surfactant is used for making ice cream, margarine, paints, inks, etc.

2）Moistening, osmosis,
Water normally forms spherical and roll on lotus leaves, however, water is spread on surface of the leaves when surfactant is dissolved in it. By using this function of surfactant, agricultural chemicals can be sprayed thinly and evenly onto leaves, so that large effect can be produced with small amount. Also, it is used for infiltrating dyestuffs and finishing agent evenly into fiber, leather, etc. since it makes water to infiltrate more easily. 

3）Forming, Deforming
Water that surfactant is dissolved makes foams easily. This is because surfactant makes water to take in air bubbles and make the bubbles stable to be kept their form. Also, some kinds of surfactant reduce foams, so that they are used when foaming need to be prevented.

4）Cleaning
Stains of oils and sweat are hardly removed. By using surfactant, it moistens both clothe and stain, takes off the stain by soaking into space between the clothe and stain, and also remove the stain by emulsifying and breaking down. In other words, multiple function of surfactant cooperate and stains are removed. Cleaning is an important process in many fields. For example, woolen textile starts with removing process of dirt of wool, then the wool is washed many times until it becomes fabric. Paper manufacturing starts with cleaning and bleaching the pulps reduced from wood, and also in metal industry, degreasers and detergents are necessary.

Detergents used in cleaning process contain surfactants, therefor oils are removed completely by this component. However, the surfactant affects on effluent treatment process in various ways.
For example, it causes negative effects such as foaming during effluent treatment process or increasing COD (Chemical Oxygen Demand). Cleaning process is an essential process in manufacturing, however, some kinds of measures to reduce its effect is necessary during treatment process of the water used for cleaning.
One of the counter measures is to use appropriate flocculants during effluent treatment and dehydration treatment processes. By using the appropriate flocculants, function of surfactant is weakened and condensation is done stably.
The flocculants are chemical agents to gather particles dispersed in muddy water and make assemblies, then let them settle to the bottom. Lumps of gathered particles are called aggregates or flocs. By settling the particles to the bottom, it becomes easy to separate water and flocs. This is used for settling tank and dehydration stage during water treatment process.

Drying process of the wastes discharged after effluent treatment and dehydration process such as sludge is affected by the flocculants.
Sludge containing flocculants are almost always agglomerated as the drying process goes on. The condition of them is sludge-like when they are fed to dryer, however, they form grains and lumps as they are heated and dried. It becomes difficult to dry inside as the lump get bigger since heat hardly reach to inside. Inner part is not dried even surface is dried.

Our KENKI DRYER dries and discharges material as small grains without forming lumps even it is organic sludge. As the size of grain gets smaller, it is heated and dried better from inside.
The reason is our agglomeration preventive function of the material to be dried.
Because of our original technology with international patent, blade inside the dryer cuts off the material to be dried when the blades passed by each other and when edges of blade touches trough.
Agglomeration can be prevented by repeating the cutting off process in the above.

Please refer to the following page for further details of our agglomeration preventive function of material to be dried.

Self-cleaning screw

Please refer to the following page for about effects of flocculants during drying process.

About effects of flocculants during drying -1 / Sludge drying, Recycling drying

Comparison of drying between organic sludge and inorganic sludge after dewatering

Comparison between organic sludge and organic matter