The high-load anaerobic reactors are great alternatives for treating effluents with high concentrations of organic load with lower power consumption and reduced sludge production. However it is overly dependent on the sludge granulation capacity and performance is easily affected by variations in effluents composition, complicating the operation.

Additionally, the effluent usually requires a polishing, generally obtained by aerobic treatment. Another limitation is the fact that the anaerobic reactors do not remove nutrients.

On the other hand the technologies that uses aerobic reactors require lower costs for installation, but require higher energy consumption and larger surface areas to remove large organic loads.

The innovative DACS DANA System ("Downflown Aerobic Dynamic Anaerobic Aerobic System") was developed in order to unify the advantages and overcome the limitations of both types of reactors..
It consists of a reactor designed for medium and high load effluents which combines anaerobic and aerobic reactor into a single unit, as illustrated in the schematic representation inserted beside:
In DACS DANA these reactors are overlapped and consist of two attached biomass reactors, in which the microorganisms grow forming biofilms on PEAD biomass carriers. The carriers are designed to provide a high internal area (650 m2 of protected area / m3 plastic carrier).

Carriers are drilled to prevent clogging, facilitating oxygen transport, biogas and substrates for biofilm. Another difference is the constant clash between the carriers, which is important to assist the detachment of the biofilm when its thickness increases excessively.

The effluent is circulated in a downward flow to the anaerobic compartment, performing an upward trajectory for aerobic compartment (in which reactor occurs polishing, removing the residual organic load and part of the nutrients).

High volumetric organic loads are applied (15-20 kg / m3.d), making them very compact reactors.

Other advantages of the DACS DANA reactor are:

- The technology is simple and contains few internal, being very easy to accomplish "retrofits" of aerobic and anaerobic reactors complete mixture;

- Due to adherence in the biofilm formed on the biomass carriers, conversion of particulate organic material into biogas affluent exceeds in the anaerobic compartment;

- The performance of anaerobic compartment independent of the sludge ability to form granules;

- The concentration of biomass per cubic meter reactor is much higher when considering that there is a fraction of biomass suspended and a large amount of biomass attached in the carriers. So it becomes possible to design more compact reactors;

- The contents of H2S and CO2 in the produced biogas are less (are dissolved in the treated effluent) because the effluent flow in the DACS is downward. Thus the potential energy of the biogas obtained is greater;

- As the thickness of the biofilm increases in the aerobic compartment, the superficial regions of the biofilm are predominantly aerobic (prevailing the carbonaceous oxidation and nitrification) and regions near the biomass carriers assume character next to the anoxic (denitrification occurs in significant amounts). Thus, in the same reactor can be removed a wider range of pollutants (ammonia, nitrite and nitrate);

- Operation of the system is simple and requires minimal automation, enabling the implementation of the system in places with few resources, and stations where the operation is shared with other units such as, for example, the areas of the various utilities industry segments;

- The durability of carriers is high, with 20 year warranty for biomass carriers (both sanitary and industrial effluents).

The technology of anaerobic reactors DANA DACS was developed by Dutch company AQANA, which belongs to the group AQWISE.

Since 2013 the UPE has a partnership with the Israeli group AQWISE to provide biological treatment systems with attached biomass.

The AQWISE Israeli company is a world leader in deploying adhered biomass in moving bed systems. With extensive operations in the Americas, the Middle East, Europe and Southeast Asia, the AQWISE implemented MBBR systems, IFAS, DACS and DANA DACS in more than 300 municipal and industrial facilities spread across 35 countries.

The partnership between the UPE and AQWISE enables the development of customized projects according to the specific needs of each client