Bioavailability and characterization of dissolved organic nitrogen and dissolved organic phosphorus in wastewater effluents

There is still a great knowledge gap in the understanding of characteristics and bioavailability of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in wastewater effluents, which surmise implications related to both discharge regulation and treatment practice. In this study,...

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Bibliographic Details
Published in:The Science of the total environment 2015-04, Vol.511, p.47-53
Main Authors: Qin, Chao, Liu, Haizhou, Liu, Lei, Smith, Scott, Sedlak, David L., Gu, April Z.
Format: Article
Language:English
Subjects:
Algae
Bioavailability
Dissolution
Dissolved organic nitrogen
Dissolved organic phosphorus
DON
Dopants
Effluents
Environmental Monitoring
Eutrophication
Fluorescence spectroscopy
Hydrophilic
Hydrophobic fractionation
Nitrogen - analysis
Nitrogen - chemistry
Phosphorus - analysis
Phosphorus - chemistry
Plants (organisms)
Resins
Waste Disposal, Fluid
Waste water
Waste Water - chemistry
Wastewater effluent
Wastewater treatment
Water Pollutants, Chemical - analysis
Water Pollutants, Chemical - chemistry
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Summary:There is still a great knowledge gap in the understanding of characteristics and bioavailability of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in wastewater effluents, which surmise implications related to both discharge regulation and treatment practice. In this study, we simultaneously investigated the characteristics and bioavailability of both DON and DOP, with separated hydrophilic versus hydrophobic fractions, in highly-treated wastewater effluents for the first time. The tertiary effluents from two wastewater treatment plants were separated into two fractions by XAD-8 resin coupled with anion exchange resin based on the hydrophobicity. Results showed that the majority of DON was present in hydrophilic forms while more DOP existed in hydrophobic forms. Hydrophilic DON contributed to 64.0%–72.2% of whole DON, while hydrophobic DOP accounted for 61.4%–80.7% of total DOP for the two plants evaluated. The effluents and their fractions were then subject to bioavailability assay based on 14-day algae growth. The results indicated that majority (~73–75%) of the effluent DOP, particularly the hydrophobic fraction with lower C/P ratio was more likely to be bioavailable for algal growth. The bioavailable fraction of DON varied widely (28%–61%) for the two plants studied and the hydrophilic fraction with lower C/N ratio seemed to exhibit higher bioavailability than the hydrophobic portion. The differences in bioavailable DON and DOP distributions of effluents from those two plants could be attributed to different receiving effluent compositions and wastewater treatment processes. In addition, fluorescence excitation–emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) were used to characterize the dissolved organic matter (DOM) in wastewater effluent, which provided insights into the nature of organic matter in wastewater samples with different characteristics and originating sources. [Display omitted] •The bioavailability of DON/DOP in wastewater effluents were examined.•The majority of DON was hydrophilic while more DOP existed in hydrophobic forms.•Hydrophobic fraction of effluent DOP was more likely to be bioavailable for algae.•Hydrophilic fraction of effluent DON seemed to exhibit higher bioavailability.•Fluorescence spectroscopy analysis provided insights of DOM in wastewater effluents.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2014.11.005