Spotlight on water technology products: What is...?

How many of you still remember Alf? You're probably thinking of the little red-haired alien? Well, I can tell you that he's not the one I have in mind. More than twenty years ago, the water technology product families included Donau Klar, Donau PAC and Alf, Donau Alf. The Alf products have since been replaced by Donau Acquabella. Donau Bellair, Donau Bellamethan, Donau Press and Donau Evolution complete the extensive portfolio.

But what do they stand for?
 

Donau Klar: Classic coagulant for wastewater and drinking water treatment

On the one hand, there is our classic Donau Klar: For more than 30 years, Donau Klar classic has been synonymous with high quality. Over the years, a number of variants have been added, such as Donau Klar ferro, Donau Klar smart and several others. These differ in concentration and content of accompanying substances. All products meet the requirements of the EN 888 standard (chemicals used for treatment of water intended for human consumption – Iron(III)chloride) with regard to the accompanying elements.

Donau Klar is the classic coagulant for the removal of phosphates from wastewater. As a cationic coagulant, it also improves the settling of activated sludge, removes turbidity in drinking water treatment and organic loads in primary clarification or industrial wastewater treatment. The use of Donau Klar products also results in a reduction of the hydrogen sulfide content in the digester gas.
 

Donau PAC: Effective flocculation processes with polyaluminum chloride

For a long time, iron salt solutions were the main phosphate precipitating agents used in Austria's waste water treatment plants. In the 1990s, a mysterious product that had originally been developed in Japan for the treatment of drinking water began to appear more frequently: Polyaluminium chloride - a rather strange chemical substance. We have grouped these kinds of products together as the Donau PAC family. Like ferric chloride, PAC is an inorganic metal salt. However, because of its special structure, it forms polymers known as ion clusters.

For coagulation processes, e.g. for turbidity removal in drinking water plants or in industrial wastewater treatment processes, high basic PAC products such as Donau PAC Venezia, Donau PAC calzifloc or Donau PAC LOTUS are particularly suitable. The classic Donau PAC activis supplements the iron products in phosphate precipitation. The polymeric structure leads to better floc formation and additionally the product supports the wastewater treatment plant in the control of bulking and floating sludge incidents.

Aluminium products (alum or aluminium sulfates) have been used in paper making since the 19^th century. They have even been called "paper makers' aspirin". Changes in the papermaking process and the increased use of recovered paper resulted in at least partial substitution of "alum" by the less acidic polyaluminium chloride.
 

Donau Acquabella: A wide range of wastewater treatment options tailored to your needs.

Both types of metal salts ("Klar" and "PAC" families) have partly similar functionalities, but also substance-specific advantages. So, we soon started combining the products and adding additives to make them suitable for specific applications. The resulting product group was initially marketed under the name Donau Alf.

With these products, excellent phosphate elimination is guaranteed, and at the same time they can also fix hydrogen sulfide, for example, and resolve malfunctions in the sedimentation properties of the biological sludge - and everything in close coordination with the requirements of the wastewater treatment plant. "No problem!" the little extraterrestrial namesake would say.

The Donau Alf products have since been integrated into the new Donau Acquabella product line. The products of the Donau Acquabella Group can do everything that the Alf products can do. They offer additional benefits such as more variation and customisation options. This makes them even better at their many wastewater treatment tasks.

Incidentally, the quality meets the requirements for drinking water treatment, where flocculation and coagulation are also required.
 

Donau Evolution: Long life iron and aluminium combinations

According to the Merriam-Webster’s Dictionary, evolution is defined as "a process of gradual advance". And that is exactly what the products of the Donau Evolution family stand for. Established combinations of active ingredients in a completely new form. In Donau Evolution products, we have succeeded in creating combinations of iron and aluminium solutions that can be stored almost unlimited time.
 

Donau Bellair: Selective sulfur fixation and phosphate precipitation in one solution

Donau Bellair products are the first choice when only sulfur compounds need to be selectively removed from wastewater. They are optimised for the specific requirements of odour control in sewer systems. In this case, phosphate precipitation is of secondary importance. The highly selective effect and the fact that the active ingredient can be used several times are the particular advantages of Bellair products for odour control in wastewater:

In the sewer, hydrogen sulfide is effectively fixed and the odour problem is solved; in the aerated zone of the biological treatment step, the active ingredient is released and is available for phosphate precipitation. Finally, sulfides can be precipitated again in a downstream digestion tower. This is economic cascade utilisation.
 

Donau Bellamethan: Eco-friendly solutions for biogas plants

The products of the Donau Bellamethan family not only reduce the concentration of hydrogen sulfide in the biogas, but also permanently fix the free sulfides (H₂S), which inhibit methane production, as insoluble iron sulfides. In addition, the acidic nature of the products helps to shift the ammonium-ammonia balance towards ammonium. This reduces the amount of ammonia entering the gas phase and retains the important nitrogen in the fermentation residue.
 

Donau Multifloc and Donau Press: Effective flocculation and decalcification

Finally, it remains to be resolved what Donau Press and Donau Multifloc might be. Unlike the previously mentioned ones, these are not inorganic coagulants. Donau Multifloc are classic organic polymers. They are used as flocculants in sludge dewatering and for flocculation in industrial and drinking water treatment.

Lime deposits in dewatering equipment, such as chamber filter presses, must be removed regularly.  Treatment with diluted acid, usually hydrochloric acid, has proved effective. For a better result with less corrosiveness, the products of the Donau Press family have been developed. They have proven themselves in many years of use. Other types of scale can also be removed using Donau Press products.
 

Continuous development of water technology products

As you can see, Donau Chemie AG's Water Technology Group offers a wide range of chemical products for water treatment. As requirements change, new regulations emerge or existing ones become more stringent, Water Technology products are subject to constant further evolution.

For example, the removal of micro pollutants will become increasingly important in the coming years. Here, too, we are working at the cutting edge to find a solution and can draw on the knowledge we already have. We do, in fact, have an experienced activated carbon manufacturer in the group with Donau Carbon.

Our Donau PAC Aquaclear, which has already been tested at the Vienna University of Technology, is a promising first result of this synergy. You can read about the exciting results in the latest issue of ÖWAW and in the Journal of Environmental Chemical Engineering.

This brings me to the end of my little excursion into the world of Donau Chemie's water technology products. There will be more to come - I can promise you that...