P-removal in completely mixed systems
Ca. 60 % of the Dutch activated sludge plants consist of completely mixed systems, experiments have been carried out in completely mixed pilot plants to study the biological P-removal. The research was carried out in two pilot plants. The pilot plants consisted of: anaerobic reactor, anoxic reactor,...
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Veröffentlicht in: | Water science and technology 1985-11, Vol.17 (11-12), p.325-326 |
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Sprache: | eng |
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Zusammenfassung: | Ca. 60 % of the Dutch activated sludge plants consist of completely mixed systems, experiments have been carried out in completely mixed pilot plants to study the biological P-removal.
The research was carried out in two pilot plants.
The pilot plants consisted of: anaerobic reactor, anoxic reactor, aerobic reactor and a clarifier. All the reactors were completely mixed.
Both plants were fed with settled domestic waste water at a sludge loading of 400 and 250 g COD/kg sludge.day respectively. The results are given below:sludge loading (g COD/kg sludge.day)400400250ratio Anaerobic : Anoxic : Aerobic1: 1:2,71:1:4,11:1:2,7P-removal (%)802875N-removal (%)505065COD-removal (%)858585
It has been shown that there is no significant difference between the results at the two different sludge loadings.
Remarkable is the difference between the ratio 1:1:2,7 in combination with the internal recirculation flow anoxic-anaerobic of 160 % and the ratio 1:1:4,1 with a recirculation flow of 30 %.
During the start-up at a sludge loading of 250 g COD/kg sludge.day and an internal recirculation flow of 30 %, bulking sludge developed almost immediately. The Premoval was completely disturbed.
Increasing the internal recirculation flow to 160% had a positive effect on settling properties and P-removal.
This investigation has pointed out that a completely mixed system is suitable for biological P-removal, without negatively affecting the nitrification. Important factors in the process are the ratio anaerobic:anoxic:aerobic and the recirculation flows. |
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ISSN: | 0273-1223 1996-9732 |
DOI: | 10.2166/wst.1985.0254 |