Monitoring of effluent DOM biodegradation using fluorescence, UV and DOC measurements.
The potential of effluent DOM to undergo microbial degradation was assessed in batch experiments. Effluent samples from Haifa wastewater treatment plant and Qishon reservoir (Greater Haifa wastewater reclamation complex, Israel) were incubated either with effluent or soil microorganisms for a period of 2-4 months and were characterized by dissolved organic carbon contents (DOC), UV(254) absorbance and by fluorescence excitation-emission matrices. Three main fluorescence peaks were identified that can be attributed to humic/fulvic components and "protein-like" structures. During biodegradation, specific fluorescences (F/DOC) of the three peaks were increased at various extents, suggesting selective degradation of non-fluorescing constituents. In some cases increase in the effluent fluorescence (F) was observed thus proposing (i) the formation of new fluorescing material associated with DOM biodegradation and/or (ii) degradation of certain organic components capable of quenching DOM fluorescence. Based on the ratio between fluorescence intensity and UV(254), different biodegradation dynamics for fluorescent DOM constituents as compared with other UV-absorbing molecules was delineated. Overall, about 50% of the total DOM was found to be readily degradable such that residual resistant DOC levels were between 8 and 10 mg l(-1). Enhanced levels of residual DOM in effluent-irrigated soils may contribute to the DOM pool capable of carrying pollutants to groundwater.
Saadi
Ibrahim
I
Agricultural Research Organization, Institute of Soil, Water and Environmental Sciences, Newe Ya'ar Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel.
Borisover
Mikhail
M
Armon
Robert
R
Laor
Yael
Y
D000383:Agriculture / Q000379:methods; D001578:Benzopyrans / Q000032:analysis; D001673:Biodegradation, Environmental; D002244:Carbon / Q000032:analysis*; D004784:Environmental Monitoring; D005308:Fertilizers; D005453:Fluorescence; D006812:Humic Substances / Q000032:analysis; D007557:Israel; D011506:Proteins / Q000032:analysis; D013056:Spectrophotometry, Ultraviolet; D014865:Waste Disposal, Fluid
D001578:Benzopyrans; D005308:Fertilizers; D006812:Humic Substances; D011506:Proteins; D002244:Carbon; C005023:fulvic acid