Denitrification alternatives



Reference flow in the MFA for which is suitable the technology

190703 - Leachate generated in an old landfill site for municipal solid waste

Incoming input

Leachate from a municipal waste landfill in aftercare phase (capping installed). The pollution load is relatively low

Outgoing output

Biologic sludge (recovery/disposal) + N2 to atmosphere + water effluent with a far lower nitrogen concentration.

Technology description

Anammox bacteria convert ammonium (NH4+) and nitrite (NO2-) into nitrogen gas. They are autotrophic and are active in a wide range of temperature. Possible reactors are sequencing batch reactors (SBR), moving bed reactors or gas-lift-loop reactors. Annamox, as example of alternative denitrification reactor, potentially required a minor duration of the previous oxidation phase. 

Organizative processes to support closing the loops

Practitioners opinion

Compared to conventional nitrification/denitrification savings on operational costs can reach up to 60%, while CO2 emission is reduced. The cost reduction compared to conventional nitrogen removal is considerable; the technique is still young but proven in several full-scale installations. The high capital costs balance the higher operation costs of traditional treatment nullifying possible economic advantages. A patent exist above Annamox bacteria, therefore expenses exist at every reactor restoration. 

Possible limiting factors

The doubling time is slow, between 10 days to 2 weeks. This makes it difficult to grow enough sludge for a wastewater treatment reactor. Also the recovery time after the loss of sludge by accident is longer than in conventional nitrogen removal systems. Depending on the exact species, the optimum pH level is 8. Therefore it can be necessary to adjust the pH of the wastewater by adding chemicals.

PP’s opinion of the technology

Since 2000 the bacteria are studied and the first technologies developed (above all in the Netherlands and Germany); there are still managerial difficulties for the reactor monitoring also because of low number of application and full-scale experiences.

Concept and conclusions how the technology can affect the CE effect

The low number of experiences increase the uncertainties of costs and efficiency rates. There is not a direct recover of valuable material (as in the previous solution), even if a correct management of alternative denitrification reactors results in a lower amount of generated sludge.

Is the technology a BAT?

Charts, photo, diagrams



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