Single-reactor technology of nitrogen removal from wastewater

Summary

The experts of R&D Centre of «Mosvodokanal» OJSC developed high-effective technology of removing nitrogen from wastewater. The technology was tested at the Kur’ianovo wastewater treatment plant of the city of Moscow during processing filtrate of the digested sludge belt thickeners. The method is based on the use of specific Anammox-bacteria that oxidize ammonium with nitrite under anoxic conditions. Filtrate is processed in a sequencing batch reactor with complete mixing (SBR-reactor). Partial nitrification processes (ammonium oxidation into nitrite), ammonium oxidation with nitrite and organic matter oxidation are carried out in one reactor. Retention of extremely slow growing biomass of Anammox-bacteria has been a critical problem for all the reactors. In this particular case the problem was solved with bacteria adhesion on the reactor walls and the feed as well as with flotation. To evaluate the treatment efficiency standard methods were used. The developed single-reactor modification of the anoxic oxidation of ammonium differs from the well-known by the following parameters: high nitrogen removal efficiency, the method of biomass bacteria retention in the reactor, the availability of new Anammox bacteria, heterotrophic denitrification. All other conditions being equal the integration of Anammox single-reactor technology requires the size of the facilities ten times smaller than double-reactor technology; for this reason it is more preferable for implementation. The new technology was given the name AUTOHETAMMOX.

Key words

wastewater , nitrogen removal , bioreactor , nitrification-denitrification , anammox bacteria

Development of the first in Russia Anammox type technology

Summary

The first in Russia Anammox type technology has been developed in «Mosvodokanal» JSC in cooperation with «Fundamental principles of biotechnology» Federal Research Centre of the Russian Academy of Sciences with support from RF Ministry of Education and Science. The technology is designed for the purification of filtrate of centrifuges that dewater digested wastewater sludge. Anammox technology is based on the microbiological process of ammonium oxidation with nitrite under anoxic conditions. This process has been implemented at more than 100 wastewater treatment facilities all over the world in various technologic options. This group of technologies is the most cost-effective and high developing biotechnology of nitrogen removal from wastewater. Anammox type technology has been implemented at the pilot plant that provides for the purification of dewatering centrifuge filtrate. In terms of the process parameters the developed technology can be compared to the foreign alternatives but adapted to the conditions of the Liuberetskie Wastewater Treatment Facilities in Moscow. Single reactor process is carried out at 30–37 °С with new anammox-bacteria. From the economic, technologic and environmental point of view Anammox technology is very attractive compared to the traditional options of biological nitrogen removal. Anammox process lacks the demand in organic matter; whereas the oxygen demand is reduced by 60% resulting in significant energy saving. It can be applied at the wastewater treatment facilities both in Russia and overseas.

Key words

wastewater , pilot plant , anammox bacteria , ammonium removal technology , large-scale bioreactor , dewatering centrifuge filtrate