At one of the largest landfills of eastern Austria large quantities of household waste had to be loaded and disposed by incinerating. Already at the beginning of the operation it turned out that the odour nuisance for the population was too heavy and this resulted in massive neighbour complaints.

The wind mostly blowing from west to north-west drove odours to an eastern settlement. A solution had to be found to remove the household waste without creating significant odour problems.

ACAT recommended a procedure to eliminate odours directly at the source by atomizing Ecosorb ™.

Mechanism of Ecosorb™action:

Ecosorb ™ is a blend of natural essential oils and emulsifiers, it is non-toxic and biodegradable.

Highly diluted Ecosorb ™ (1:10 – 1:2000) is sprayed directly over the odour source. Once the odour molecules come into contact with the finest water droplets, they are adsorbed into the droplet and they are no longer perceived to be bad smelling.

The tiny water droplets have a thin oil skin creating electrostatic charge.  The charge facilitates the adsorption of the malodourous molecules onto the droplet surface. Although the water drops exists only for a few moments the malodour molecules are captured and neutralized.

First, several tests were carried out at the landfill with two turbofans with a theoretical throwing range of up to 30 meters. Finally it was decided to treat the area with a turbofan and a high pressure system with 100 nozzles.

This treatment made it possible to load about 13,000 tons of household waste. The close cooperation with the local residents could eliminate quickly temporarily accumulating odour problems. Such problems sometimes occurred at low wind speeds. Also a short-term increase of dosage up to 7 l / h helped to avoid odour nuisance.

During the treatment period the average daily dose was about 25 kilograms per day or 0.100 kg Ecosorb ™ per ton loaded household waste. As the treatment was successful the spraying systems were purchased. They continue to be used in order to prevent any arising odour problems in time.

The substances, which are responsible for the diffusion of odors into the atmosphere in the vicinity of treatment plants, are generally inorganic gas products or highly volatile organic compounds. The inorganic products are mainly the result of biological activity in sewage and the organic compounds are often caused by the presence of industrial waste, in the sewer.

The following compounds are associated with bad odors:

• Mercaptans,
• Inorganic acids,
• Aldehydes,
• Ketone
• Organic compounds which

contain nitrogen or suflur atoms.

These compounds are a result of the anaerobic decomposition with a high molecular weight, especially

proteins and are recognized as being among the causes of bad smelling odors at the outlet of sewer lines and in treatment plants in general.

Ammonia and hydrogen sulfide, which are the inorganic compounds, are considered to be the main cause of odor, when the sewage comes mainly from households.

In gravity sewer systems, in which the speed of the sewage flows, thus allowing for continuous reaeration, there is no significant production of hydrogen sulfide or other odor causing reasons.

Under such circumstances, however, it has been determined that odors can still find favorable conditions to form the sludge film that covers the submerged surface of the sewer lines. The hydrogen sulfide, which is formed in these areas, diffusing into the overlying sewage, lowers the redox potential, counter‐balancing the opposite effect of the natural reaeration.

Therefore it can be understood how septic conditions may arise in low‐speed sewage which trigger very intense activities on the sulfate‐reducing bacteria.

These conditions can become more severe if the collection lines are particularly long and the system is located in a region that experiences high temperatures.

Sewage and wastewater odors are more often associated with hydrogen sulfide and ammonia. ECOSORB® 606 is the solution against these odors. In typical airborne applications of ECOSORB® products, the atomized (High Pressure System) or vaporized (Vapor Phase System) material is carried into the atmosphere where it attracts, or is attracted the odors in the atmosphere; whether it is a pleasant, malodor, or particulate odor. The selection, of which method works best, depends on the concentration of the odor causing compounds, the air flow rate, the area of the system and the capital budget. In any event, the odor is eliminated.

Wollsdorf Leder is one of the best-known tanneries in Europe and quality is a top priority of the company. Customers like Audi, BMW, Air Berlin, Deutsche Bahn and many more swear by the professionalism of the Austrian company. Here attention is paid to every detail, not only in the choice of raw materials, but also in dealing with employees and neighbors. In 2015 immediate neighbors complained about odour nuisance. There was an unpleasant, biting smell in the air. Wollsdorf leather was in the crossroads of criticism first and the company immediately acted sparing neither expense nor effort to get the problem sustainably under control. With the solution of the odour problems, a company was commissioned believing to be able to be up to the job: Two high-tech HPS plants with UV irradiation were installed, and the areas to be treated were sprayed with about 100 nozzles. The result: Wet soils, clogged nozzles, frozen pipes, leakages at various parts of the machine – but no success in neutralizing the malodours! The frustration of the management was understandably great! The information on the unsuccessful attempt to neutralize odours also reached the ACAT environmental department and we contacted the company Wollsdorf. Quickly there was a personal meeting, but the skepticism was great. After three hours of intense discussion and numerous questions and answers, the company site was visited. It quickly became clear that in this case the HPS plant was not an optimal solution. The disadvantages of such a system were obvious: Enormous water consumption, wet soils, operation in winter not possible, constant service of the nozzles.

Advantages of the VPS system in combination with Ecosorb®

As an alternative, ACAT offered a VPS system. The offer was approved and the first VPS system was built for testing purposes and leased to the company Wollsdorf.

The advantage of this system is that the odour inhibitor Ecosorb® is decomposed into minute particles and then sprayed via a pipeline into the ambient air. The odour molecules are attracted and captured by the electrostatic force of the Ecosorb® molecules. Ecosorb® acts immediately when it comes into contact with the odour molecules and it neutralizes them completely by an acid / base reaction. What remains is the naturally fresh air.

We have succeeded! No more ammonia smell!

The test area was a hall where the ammonia smell was very intense. First, it was tested with a four percent solution (Ecosorb® 606). It quickly became clear that this concentration was too high. A two-percent solution was sufficient, and Wollsdorf could also save money. For ten minutes Ecosorb® was „sprayed“ in a half-hour cycle. After a six-month test phase, it was clear: IT WORKS! The employees noticed a marked improvement. The neighbors also, but as there are still other problem areas, the odour problem had not yet been solved completely.

Two other halls are „odour treated“

As the first VPS system has been successfully in operation for one year, at the beginning of 2017 another meeting was held between ACAT and Wollsdorf. Two other halls were selected for the performance of tests: the ”Rothauthalle” and the “Äscherei”. The odour sources and the odour intensity were the same or even more intense than in the first hall treated. We did not hesitate and worked out a plan resulting in the construction of two more VPS systems.