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Removal of bis (2-ethylhexyl) phthalate from reject water in a nitrogen-removing sequencing batch reactor

Research output: Contribution to journalArticleScientificpeer-review


Original languageEnglish
Pages (from-to)103-109
Number of pages7
JournalJournal of Environmental Management
Issue number2
Publication statusPublished - Nov 2004
Externally publishedYes
Publication typeA1 Journal article-refereed


Reject water from sewage sludge processing may contain high concentrations of nutrients and organic pollutants and cause internal pollution load at a sewage treatment plant (STP) if circulated to the headworks of an STP. In the present study removal of nitrogen and bis (2-ethylhexyl) phthalate (DEHP) from reject water was studied in two sequencing batch reactors (SBRs) with different aerobic/anoxic periods during a 6-h total cycle period. Ammonia-nitrogen (NH4-N) was almost totally removed in both reactors, apparently by nitrification throughout the run, while denitrification declined with decreasing SCOD in the influent resulting in an increase in the effluent nitrate-nitrogen (NO3-N) concentration. DEHP removals from the water phases were above 95% in both reactors, while the average total removals were 36 and 42%, calculated on a mass basis. Much higher removals occurred in the experiment where one of the systems was spiked with a given amount of DEHP. The spiking experiment suggested that SBRs had the potential to remove DEHP biologically from reject water but that the removal was restricted by the poor bioavailability of DEHP as a result of sorption to solids. This study showed that SBR has the potential to cut the internal load of nitrogen and hydrophobic organic pollutants in cases where reject water is circulated to the headworks of an STP.


  • Bioavailability, Di (2-ethylhexyl) phthalate, Reject water, SBR