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Abstract

Two different porous ceramic carriers with immobilized activated sludge comprised a stationary filling of the reactors. Municipal wastewater was treated at hydraulic retention times from 15 to 70 min and internal circulation capacity of 20, 40 and 60 drn':h'. Depending on hydraulic retention time, the sludge yield ranged from 0.138 to 0.066 g TSS·g COD·' in reactor I and from 0.175 to 0.107 g TSS·g COD·' in reactor li. An increase in volumetric loading rate and internal circulation capacity caused a reduction in sludge yield. A decrease in the sludge yield corresponded to an increase in the ratio of endogenous to substrate respiration by the immobilized biomass
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Authors and Affiliations

Magdalena Zielińska
Irena Wojnowska-Baryła
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Abstract

The paper presents the results of an experiment with sugar-industry waste (molasses) as an organic carbon source for denitrification. The investigations concern the influence of untreated molasses and molasses after pretreatment (hydrolyzed molasses) and variable COD/N ratio (6.0: 5.0: 4.0) on denitrification efficiency and kinetics. Moreover, sludge production, in dependence on tested carbon source, was estimated. Al COD/N ratio 6 and 5, regardless or applied organic carbon source (untreated molasses. hydrolyzed molasses), the denitrification efficiency was over 98%,. However. from kinetic analysis it results that a kind or carbon source and COD/N ratio have an effect on denitrification rate. The highest nitrate removal rate - 9.5 mg N,0/(dm-1-h) was obtained al COD/N = 6 in the reactor with hydrolyzed molasses as a carbon source and the lowest - 5.14 mg N,0J(dm1-h) in reactor with untreated molasses at COD/N = 5.0. The lowering or COD/N ratio to 4 caused decrease otthe process efficiency to 27.6% (untreated molasses) and 44.3% (hydrolyzed molasses). Hydrolyzed molasses as a carbon source caused higher production of activated sludge. In reactors with untreated molasses Y equals 0.40 mg VSS/rng COD at COD/N ratio 6 and 0.31 111g VSS/111g COD at COD/N ratio 5. In reactors with molasses alter hydrolysis Y, were 1.35-lolcl and 1.5-lold higher, respectively. Since, the molasses hydrolysis results in rising costs of wastewater treatment and cause higher sludge production, untreated molasses seems to be a more suitable carbon source for dcniuification.
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Authors and Affiliations

Dorota Kulikowska
Karolina Dudek

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