Existing municipal effluent treatment plants designed earlier for the BOD removal are usually not suitable for nitrification at low temperatures, because of
Small plant dimensions and low sludge age, respectively
of biokinetical reasons.
Consequences are in the cases of required nitrifications expensive plant extensions.
2. Our problem solution means the
Plant upgrading into fluidised bed reactors using microorganisms immobilised on adsorbing LEVAPOR-carrier.
Immobilising nitrifying bacteria on adsorbing carriers they
become more robust and efficient,
do produce lower quantities of excess sludge and
are able to maintain their activity even after a storage over 12 months.
Upgrading of a small municipal WWTP with aerated basin of 45 m³, for nitrification in winter, by filling it with 12 vol.% of LEVAPOR carrier
As a possible alternative to plant extension, it was considered to establish the nitrification by a susequent WWTP- upgrading via immobilisation of nitrifying sludge on 12 vol.% of adsorbing LEVAPOR-carrier.
Results: After addition into the basin the carrier cubes became colonised and fluidised directly and despite to low temperatures (November) the nitrification has been established at 17°C within two to three weeks and kept efficient, achieving 70 to 80% nitrification over several months, despite to lower temperatures in December (12 °C).
TKN-inlet- and NH4N-/NO3N-outlet concentrations during nitrification at 10 to 17°C by immobilised microorganisms.
Nitrification performance of the plant at different temperatures
immobilising of the activated sludge, nitrification has been established within 2 to 3 weeks
the nitrification remained stable and efficient even at lower temperatures, of 8 to 13°C and increased volumetric N-loading rates
the existing aeration system was proven as sufficient for a practically full fluidisation of the colonised carrier cubes.
removal of excess biomass from the surface of carrier cubes occurred automatically by fluidisation without any additive measure.
B. Nitrification and removal of hazardous pollutants from municipal effluents ( pilot plant tests)
Comparison of immobilised -LEVAPOR-carrier - vs. suspended sludge
Pilot plants In two parallel operated fluidised bed reactors, each of 3,1 m³, nitrification and hazardous pollutant removal of immobilised and suspended biomass have been compared. Additionally to higher degree of nitrification and denitrification ( due to inner pores of carrier cubes ), immobilised biomass achieved also a remarkably higher removal of polycondensed aromatic compounds.
Enhanced elimination of hazardous pollutants by biomass immobilised on adsorbing, porous carrier.
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The aerated upflow biological filtration (biofiltration) is a technology which is today successfully used in more than 500 European wastewater treatment plants. Among this, the one of Sallek Valley, in Slovenia, differs by a two stage biofiltration and a part-recirculation of sludge from thickener to increase the COD concentration needed for denitrification. This process allows an advanced denitrification- nitrification in a very compact way and low operation costs. The results of the wastewater treatment plant...
The demand for efficiency improvement in municipal and industrial wastewater treatment plants (WWTP’s) is increasingly based on problems related to the water quality, process stability and/or insufficient performance in the COD removal and/or nitrification process.
New, stricter requirements or the need for higher removal efficiency intensify the demand for optimizing the existing technology by means of “tuning“.
This article is about the efficiency improvement of existing biological treatment...