Most industrial production facilities generate wastewater, which has to be treated and purified.

For many years ACAT has been dealing with the various requirements of these cleaning processes.

Usually, the first step of a purification process is the separation of the solids, which is achieved by adding various chemicals. Precipitation and flocculation cause an increase in the density difference between the particles and the liquid phase making separation possible.

Example of a Typical Flotation Plant

For many decades, precipitants such as iron or aluminium salts have been used very successfully for the pre-flocculation to achieve the desired clarity of the solution. But in some wastewater flows this process could cause undesirable side effects such as a reduction in pH, the introduction of metal ions, or an increase in salinity, etc.

Sometimes the separated solids can be reused, but the application possibilities are limited due to the use of conventional precipitants.

New Organic Polymers of Natural Origin

Currently ACAT is testing new organic polymers of natural origin.

Natural coagulants are present in two forms, first is plant based coagulants (PBC) and second is non-plant based coagulants. Natural coagulants are produced or extracted from different sources such as microorganisms, animals, or plants.

FlocStar® N is a range of coagulants composed of natural extracts from plants, algae or animals.

FlocStar® N is based on polymers of natural origin, mainly polysaccharides, substances soluble in water from materials of vegetable or animal origin that act as coagulation and / or flocculation agents. The plant-based coagulants are broadly utilized for the purification of contaminated water.

Advantages of Predominantly Plant-derived Products

The predominantly plant-derived products have many advantages compared to traditional inorganic coagulants:

• Higher efficiency
• No introduction of metals or salts
• Full efficiency in the range of pH 4-10
• Reduced sludge generation
• No change in the pH value, therefore neutralization is not necessary
• Improved dewatering properties and much more

A good example of application is the agri-food sector as it is an important consumer of water for different stages of the process.

One of the advantages of the FlocStar® N products for these sectors is that they are metal free and, therefore, do not provide metal to the sludge. Due to the organic nature of the products, a valuable sludge is obtained that can be used in agriculture.

Finally, the quality of the sludge produced is maximized, which optimizes also the amount of biogas produced. With that range of new products ACAT follows the strategy to enlarge the product range with green technology treatment processes for special applications in water and wastewater treatment.

Some producers of flocculants recommend certain quality requirements for the preparation water to produce an optimal polymer solution. These are only a recommendation for the operators, as these requirements cannot always be met. Therefore, they only serve as guide values for optimising sludge thickening or dewatering. The quality requirements and their influence on the polymer solution can be summarised as follows:

• Temperature:

Warm water accelerates the dissolving process of any polymer solution, the ideal water temperature is 10-30 °C

• pH Value:

A high pH value leads to hydrolysis (degradation) of cationic polymers. The ideal pH value for the preparation water is pH 6-8. The ready to use polymer solution should have a pH value between 4-6.

• Water hardness:

Too hard preparation water accelerates the hydrolysis (degradation) of a polymer solution. Medium-hard water 8-12 °, German hardness < 300 mg/l CaCo₃ is ideal.

• Conductivity:

Too high conductivity increases the maturing time and the dissolving process of the polymer solution, as well as its viscosity. Ideal conductivity < 10,000 µS/cm

• Solids – process water:

A solid content in the process water reacts with the polymer solution and causes deposits in the dissolving station and in the pumps. Ideally no solids or < 5 mg/l

• Divalent irons such as Fe², Cu²,…:

Free radicals can cleave the polymer chain and thus have an influence on the effectiveness. Ideal concentration < 1 mg/l

• Oxidants such as chlorides:

A too high chloride concentration can cleave the polymer chain and thus have an influence on the effectiveness. Ideal concentration < 0.5 mg/l

• Bacteria/Algae:

Bacterial growth accelerates the hydrolysis (degradation) of any polymer solution. Ideal: no biological activity

• Maturation time:

A high mixing energy and an appropriate maturation time increase the efficiency of a polymer solution. Ideal maturation: time more than 30 minutes

Analysis of the parameters of the preparation water

Using the example of AWV Völkermarkt Jaunfeld, the parameters of the preparation water for the production of a polymer solution were analysed. AWV Völkermarkt Jaunfeld operates a sludge dewatering system using IEA screw presses. The conditioning of the statically thickened excess sludge is carried out exclusively with liquid polymer. The polymer preparation station is a „tower plant“ with 750 litres batch volume per preparation. From the preparation tank equipped with an agitator, the polymer solution is transferred to the storage tank by using a transfer valve.

The maturing time is about 10 minutes! Drinking water from the local network was used for the preparation of the polymer solution. A water analysis was carried out, the exact results can be found in Table 1.

Furthermore, a polymer solution with a preparation concentration of 0.25 % commercial product = 0.125 % active polymer was prepared on a laboratory scale. The pH value and conductivity of this polymer solution were recorded over the entire period. Based on the conductivity and its course, a possible conclusion can be drawn about an ideal maturing time of the polymer solution. In a beaker, 800 ml of preparation water with about 6 °C was added and stirred with a magnetic stirrer.

Before adding the polymer, the pH value and the conductivity were noted. In addition, the pH value of the preparation water was adjusted to approximately pH 4 by adding acetic acid (0.6 ml acetic acid per 800 ml preparation water). Subsequently, 2 ml FlocStar® 200L (dispersion) were added under strong stirring and the conductivity and the pH value was recorded over the entire period.

The preparation concentration of the laboratory scale polymer solution was 0.25 % commercial or 0.125 % active polymer.

As can be seen from Table 2, the conductivity increases with increasing stirring time. The liquid polymer starts to dissolve in the water and causes an increase in conductivity.

From a stirring time/maturing time of 20 minutes, the maximum possible conductivity is reached, so that one can speak of an ideal dissolution of the liquid polymer. Therefore, we recommend a maturing time (net stirring time after reaching the maximum level of the preparation tank) of >/= 20 minutes.

The pH value of the polymer solution was about pH 4.

Summary:

An optimisation of sludge dewatering and, associated with this, a possibly higher dry residue in the discharge is particularly important in view of rising disposal costs. Depending on the sludge quality and dewatering unit, the selection of the conditioning agent is the most important factor from a technical and economic point of view.

When using solid polymer, optimum wetting of the solid polymer with the preparation water is crucial.

A sufficiently high mixing energy, a sufficient preparation volume, an optimal maturing time as well as the quality of the preparation water, are only a few parameters to dissolve the flocculant in the preparation water and thus positively influence the dewatering results. The quality characteristics of the preparation water listed above are recommendations of the polymer manufacturers. How these characteristics affect the respective sludge dewatering can only be determined empirically; it is not possible to make a general statement.

There is a whole range of factors that can positively influence sludge dewatering in terms of process technology and lead to improved dewatering values. However, the main component is always the existing sludge composition and the proportion of „free water“ (water that does not bind to the sludge particles) in the sludge suspension.

In addition to polymers and equipment for industrial and municipal sewage treatment plants, ACAT is now also your contact for splitting agents used in the garage and recycling sector. ACAT strives to be together with you at the forefront wherever environmental protection is required.

Our new product FlocStar® Wash consists of various partially water-soluble components with a very high proportion of absorbent sub-
stances and coagulating polymers. It is used in the treatment of industrial waste water to eliminate high amounts of organic and inorganic contaminants.

As required, we offer you a wide range of services together with our products. Our service technician will be happy to assist you with any questions you may have. Filter bags and filter rolls can be ordered together with the product.

The exact description of the properties of our products will help you to find the right product, but of course we will also be pleased to advise you on site. Please do not hesitate to contact us.

Plastics are produced by polymerization. Polymers: (poly = many, meros = part). Nomen est omen. In fact, carbon compounds are extracted from the raw material crude oil. In addition to these carbons, the plastic also contains the elements hydrogen, oxygen, nitrogen and sulphur. By adding plasticizers, stabilizers, reinforcing agents, fire retardants and dyes, the properties of the respective plastic can be individually influenced. Thus, many different plastics can be produced with a wide variety of properties. Plastics are mainly distinguished according to the following properties:

THERMOPLASTICS:

Thermoplastics consist of long macromolecules making it possible to form these plastics under the influenceof heat. Thermoplastics can be processed in different ways; for example they can be melted, injection moulded, foamed or glued. Primarily we know the injection moulding, in which plastic is heated and pressed into a mould under great pressure. The starting material is granulated thermoplastics. In this way, for example, the PET bottles are produced, we use almost daily.

THERMOSETS:

Unlike thermoplastics thermosets are produced by the hardening of powdery basic substances. Under high pressure and high temperature the basic substance is pressed into a mold to link the macromolecules together. Thermosets are used, for example, in mattresses, shoe soles or protective helmets.

ELASTOMERS:

Elastomers are wide-meshed cross-linked polymers. The main characteristic of these plastics is their enormous extensibility. Elastomers are able to return to their original shape even after extreme elongation. We know elastomers as rubber bands or sterile disposable gloves. One problem of all types of plastic is their disposal. We all know the frightening images of animals trapped in plastic waste and the reports of huge floating „plastic islands“ in the oceans. According to current studies, around 50 billion plastic parts are floating in the oceans of our planet.

These parts collect in the so-called current vortices of the oceans when they are carried along by the flow. Today there are five of these garbage collections in the oceans, two in the Pacific, two in the Atlantic and one in the Indian Ocean. The area of one of these „plastic islands“ is estimated to be 16 times the size of Austria. The surprising thing is that these huge „islands“ represent only one percent of the total plastic waste. The remaining 99 percent of the plastic in the sea is not visible on the surface.

WHERE IS THE REST TO FIND?

The answer is micro plastics! The majority of the packaging materials and other plastic products are not found in their original form in the oceans, but they appear much more

inconspicuous: as micro plastics. This term is used to describe plastic pieces with a size of up to five millimetres, with the smallest particles being only a few micrometres in size and thus they are invisible to the naked eye. In this form, plastic can only be detected under the microscope.

In the form of micro plastics the plastic waste is less visible in the sea, however it is no less problematic. On the contrary! This makes it even easier for the small plastic particles to find their way into the ecosystem. For example, fish and other marine animals also absorb micro plastics in their natural environment in addition to their food. This can become particularly problematic because the micro plastics in water attract chemicals, bind them chemically and this way it can get toxic characteristics. Primary micro plastics are plastics that are already small in their original form. This includes, for example, tiny plastic beads added to cosmetics to enhance the cleaning effect. These products and the containing micro plastics find their way with the waste water into the sewage system. However, these particles are so small that to the present day it has not been possible to develop suitable filters for sewage treatment plants to remove them from wastewater. Another type of primary micro plastics are small plastic pellets used to make other plastic products. They too can get into the rivers and finally the oceans via the drains of factories. The effects are devastating: On some beaches of the Canary Islands in one kilogram of sand up to 100 grams of micro plastics can be detected and plastic pellets account for a large proportion of the total quantity.

The secondary micro plastics are plastic particles having detached themselves from larger plastic parts, such as electronic waste or the like. Therefore, it is particularly important to be careful when using plastics.

It is recommended to use recirculating plastic such as PET if possible. PET – RECYCLE PLASTICS! For the production of PET polyethylene terephthalate (PET) no plasticizers and NO bisphenol A is used, as it is often wrongly claimed. In the recycling process PET must first be separated from other plastics such as PVC, HDPE bottles and impurities such as aluminum etc. Then the PET bottles and the containers are shredded. In several further steps the labels and other impurities are separated. The PET flakes enter the mixing screw, where they are mixed with 50% caustic soda (sodium hydroxide). In the kiln the flake-lye mixture is heated to temperatures from 197 to 207 degrees Celsius. The hot caustic solves

a thin PET layer from the surface of the flakes. In this way, the impurities are removed. The PET flakes are washed with water and then dried. Finally, a laser sorter measures the structure of the flakes and ejects any foreign material particles (such as silicon). At the end of the recycling process, the flakes are of such a high quality that they are suitable for food packaging.

ENVIRONMENTALLY FRIENDLY CLEANING OF WASTE WATER

To clean the waste water the caustic solution is neutralized with AluStar® products. The dirt particles are separated with FlocStar® products and various other products are used in the cooling and in the boiler area.

Thus, ACAT can make a significant contribution to the sustainable use of resources as well as to the protection of our environment, both in the reuse of PET products and in the water cycle.

Who does not know the famous milk lemon experiment? A few drops of lemon juice are enough to make a nice tasty fresh milk a flaky unappetizing liquid. An unpleasant, unwanted effect “happening” in many areas, needed to be prevented. I would like to deal with this topic today.

Milk is a classic example of an emulsion. An emulsion is a highly dispersed mixture of two normally immiscible liquids (such as oil and water). One liquid (phase) forming small droplets is dispersed in the other one. The phase forming droplets is called the internal or dispersed phase, the phase in which the droplets “swim” is called the outer phase or continuous phase. Emulsions belong to the disperse systems and they differ from completely miscible liquids, like for example ethanol and water. Usually, emulsions are cloudy, milky liquids. In the case of milk, we are happy about the stable emulsion. But in many chemical processes, the emulsified liquids have to be separated. For this purpose, demulsifiers, also called emulsion breakers, are used. Demulsifiers are typically based on acids (example: lemon / milk) or on organic compounds.

ACAT has developed a new product line of highly efficient organic demulsifiers. Our new DispStar® products are used in all areas of emulsion splitting, from the petrochemical industry to wastewater treatment.

If you are looking for a solution to such problems, please contact our field service!