Essde - Deammonification Systems

Partial nitritation , lack of nitrification and denitrification bring enormous economic advantages. An energy saving of around 60% is achieved. The operating resource costs for adding carbon are reduced to zero. The disposal costs for excess sludge are also greatly minimized. Since the EssDe  process is autotrophic, there is an important ecological advantage. The carbon dioxide is consumed in the EssDe  process (0.4 t CO2/t N), while other biological processes produce large amounts of carbon dioxide (>4.7 t CO2/t N).   

The EssDe process is technically simple and robust. The operation of a system is carried out continuously. This enables ideal living conditions for the bacteria involved in the process.

The high operational stability of the EssDe process is achieved by balancing the nitrite-producing (aerobic) and nitrite-consuming (anaerobic) biology. The growth rate of the anaerobic fraction is very slow compared to the aerobic bacteria. Therefore, a high mud age of the planctomycetes and a low one of the aerobes is required. There are 2 different sludge ages in an EssDe reactor .
Furthermore, it is absolutely necessary to keep the aerobic and fast-growing nitrate producers competing for the nitrite out of the system. This problem is solved in the EssDe  process by selectively separating the excess sludge using patented hydrocyclone technology. The return of planctomycetes ensures an enrichment of these bacteria, which is why a system is more resilient and resistant to disruption. At the same time, the shear forces generated in the hydrocyclones lead to the removal of disruptive diffusion barriers from the surface of the anaerobic organisms. The limitation of diffusion can be triggered by excess polymer or other ingredients in the wastewater to be treated.

Typically, the EssDe  process is used to treat municipal, highly concentrated sludge water (in the side stream ). To ensure a quick start, a corresponding amount of granular, anaerobic inoculation sludge is made available in new plants. With the help of a control system and simple measurement technology, the EssDe  process ensures stable process quality and easy control of the process flow.

In addition to sludge treatment , deammonification or nitrogen elimination is a crucial cost factor in wastewater treatment. The EssDe ® process provides a very efficient and cost-effective solution.

During anaerobic fermentation in the digestion tower of a biogas or sewage treatment plant, the nitrogen bound in the organic matter is released as ammonium nitrogen (NH 4 -N). The centrate of the dewatered digested sludge is very highly contaminated with NH 4 -N. Treatment in the sewage treatment plant without deammonification is cost-intensive and puts a strain on the biological purification stage.

Conventional nitrification / denitrification converts ammonium into nitrite and then into nitrate with the help of specialized bacteria. However, nitrate must be denitrified again with the addition of an external carbon source.

As early as 1997, we (as Cyklar GmbH at the time) installed the first deammonification systems for separate sludge water treatment (e.g. Bern/CH, Glarnerland/CH), in which denitrification was carried out starting from nitrite (denitritation). By avoiding nitrate, 25% energy and 40% carbon (methanol) could be saved.

With deammonification, the EssDe ® process, only 50% of the ammonium is oxidized to nitrite. The nitrite formed is subsequently reduced with the remaining ammonium to nitrogen gas. Compared to conventional nitrification/denitrification, this results in total savings of around 60% in energy consumption. The consumption of external carbon, which is the main cost factor of sludge water treatment, is reduced to zero.   
 
Technically, this process for eliminating ammonium in sludge water is carried out in a continuously operated system. Typical of the EssDe ® process, deammonification, is the intense red color of the biological sludge. The anaerobic bacteria form large, densely packed granules (10 10 cells ml -1 ), which have good settling properties. The growth rate of this mud is very slow, which is why a high mud age is mandatory.

The EssDe  process is used for highly concentrated wastewater with the aim of returning the efficiently pretreated wastewater (typical efficiency 80 - 95%) to the main stream.

Typical applications for the EssDe process are the centrate from sludge treatment, wastewater from biogas plants, landfill leachate or high-nitrogen wastewater from industry.

Nitrogen elimination is carried out especially in industrial applications in such a way that the carbon (BOD) is first eliminated and the nitrogen is then removed in a further stage. In the EssDe  process, carbon and nitrogen can be eliminated very efficiently and cost-effectively in a single process step, provided the carbon/nitrogen ratio is acceptable.

While previous applications were limited to NH4-N > 500 mg/l, today even slightly contaminated wastewater is advantageously treated with the EssDe process.

As a rule, laboratory tests are carried out to rule out any possible inhibition of wastewater in new applications. In special cases and at the customer`s request, semi-technical tests can also be carried out.

The EssDe  process saves 60% of the energy consumption of a conventional system. The addition of external carbon can be completely eliminated. This means that the amount of excess sludge produced is extremely low and the corresponding disposal costs are minimized. The result is a saving in operating resource costs by a factor of 10.

The EssDe  process is technically simple and robust. It can be designed for both continuous operation and batch operation. The investment costs are in the range of alternative processes. Thanks to the savings in operating resources, the process is extremely competitive overall.