Paques b.v.

Major Breakthrough in Wastewater Nitrogen Removal


Courtesy of Paques b.v.

Working together in close collaboration, the Hollandse Eilanden en Waarden Water Authority (Zuiveringsschap Hollandse Eilanden en Waarden, ZHEW) and Paques are pleased to announce the world's first system for sustainable nitrogen removal from waste water. In May of next year, an Anammox® system will be opened in the Dokhaven waste water purification plant of ZHEW in Rotterdam. Through the combination of the Anammox® process with de existing nitrogen removal plant (SHARON - process), a high level of sustainable and economical nitrogen removal from the rejection water of the sludge digestion plant will be achieved.

The Anammox® process was developed in the 1990s by the Delft University of Technology. Paques, that specialises in the development and manufacture of biological water purification systems, then developed the process for commercial purposes. ZHEW, that was involved in the development of the process from a very early stage, saw the economic and environmental benefits of the process, and decided to commission the first industrial application of the Anammox® process.

Brocadia Anammoxians

The Anammox® process is based on the short-circuiting of the nitrogen cycle: ammonium and nitrite are converted directly into harmless nitrogen gas. The bacteria used to trigger this process, Brocadia Anammoxidans, occurs naturally in ammonium-rich environments. The process creates a saving of about 70% in aeration energy and works entirely without chemicals. Both the operational costs and the CO2 emissions are ten times lower compared with conventional nitrification/denitrification processes. Moreover, the system only requires half the space.

As well as applications in municipal waste water treatment, the Anammox® process is also very interesting for the treatment of all types of waste water with a relatively high nitrogen level and a low organic density, occurring in the (petro)chemical, food, fertiliser, and manure processing industries. There is already international interest in the process; not only in Europe, but also in Japan and Australia.

Paques has developed a low cost sustainable solution for NH4+ removal in waste water treatment, especially applicable for high ammonia containing municipal or industrial waste water.The partial nitrification and anaerobic ammonium oxidation (Anammox®) processes are completely new treatment concepts in biological ammonia removal from waste water. The processes are a short-cut in the nitrogen cycle for ammonia conversion into nitrogen gas. 70% of the oxidation energy for nitrification and 100% of the electron donor for denitrification can be saved. Nitrogen removal based on this concept consists of two treatment steps: partial nitrification followed by anaerobic ammonium oxidation.

Partial nitrification

The first step is the partial nitrification of the ammonia. In this step 50% of the ammonia is biologically converted to nitrite, using nitrifying bacteria. Partial nitrification requires oxygen and therefore (limited) aeration is required. Our CIRCOX® reactor is particularly suitable for this process, due to its efficient mass transfer and mixing, leading to a small footprint and compact design. The partial nitrification process is patent protected. The process ensures a required ammonia conversion efficiency of 50%.

Anammox® (anaerobic ammonium oxidation)

The second step is the anaerobic ammonia oxidation (Anammox® process). In this step, ammonia and nitrite are biologically converted into nitrogen gas. The Anammox® process proceeds only in the absence of oxygen. Our gas-lift-loop Anammox® reactor is particularly suitable for this process. This type of reactor ensures excellent mass transfer, mixing and biomass retention. This results in a stable and compact process.
The combined partial nitrification-Anammox® process is a very competitive and sustainable process since less energy is consumed and no chemicals are required as compared to the conventional nitrification and denitrification process. As a consequence CO2 emission can be reduced by 88% as indicated in the table.

CO2 emission

The combined partial nitrification -Anammox® process is very cost-efficient: 90% reduction of operational costs compared to conventional technology for ammonia removal from medium to high strength waste streams (typically > 400 mg/l ammonium-N) containing little or no organic carbon, such as for example rejection water from sludge digestion or effluents from anaerobic wastewater treatment. Also sour water from the oil and gas industry and NH3-containing gasses can be treated effectively using the proposed process. 

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