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| Titel: |
Fate of trace organics during land application of municipal wastewater |
| Auteur: |
Hutchins, S. R. Tomson, M. B. Bedient, P. B. Ward, C. H. Wilson, John T. |
| Verschenen in: |
Critical reviews in environmental science and technology |
| Paginering: | Jaargang 15 (1985) nr. 4 pagina's 355-416 |
| Jaar: |
1985 |
| Inhoud: |
Recent developments in analytical techniques have provided a better characterization of trace organics in municipal wastewater and have increased public awareness concerning potential health risks of renovated waters. Although renovation of wastewater by land application is an economical alternative to conventional treatment processes and can provide comparable treatment with respect to standard water quality parameters, there have been few quantitative studies on the fate of trace organics in these systems. This review evaluates the potential for trace organic removal by abiotic and biotic processes during rapid infiltration, irrigation, and overland flow of municipal wastewater. Special emphasis is directed towards rapid infiltration because this method of land application has the greatest potential for affecting associated groundwaters. Many trace organics which are present in municipal wastewater are transported to groundwater during rapid infiltration, although concentrations of most compounds are attenuated by the process. Much of the removal can be attributed to microbial activity. Labile compounds are readily degraded by both soil and wastewater microorganisms, whereas the fate of recalcitrant compounds may be primarily influenced by abiotic processes. Biodegradation of most trace organics is clearly enhanced by the presence of an acclimated microbiota and is usually inhibited by the development of anaerobic conditions. This implies that trace organic removal can be optimized by maintaining aerobic conditions in the soil during flooding. Even so, biodegradation of most compounds is generally incomplete. In many cases, rates of mineralization are much less than rates of biotransformation. Hence, one of the results of microbial involvement may be the production of metabolites which are more refractory. In addition, for several compounds there is a threshold concentration below which further removal does not occur, regardless of whether the compound is being used as a primary substrate. This indicates that groundwater contamination by trace organics will probably result from rapid infiltration of wastewater, and this has been observed in field studies as well. In contrast, enhanced removal of trace organics should occur during either irrigation or overland flow of municipal wastewater because the rate of application is much lower and significant water loss occurs by evapotranspiration. Hence, the rate of movement to groundwater is much slower and the compounds are in contact with the degradative consortia of microbes for a longer period of time. In addition, the roles of sorption and volatilization are more important in slow rate systems than in rapid infiltration systems. Additional research is required to develop design criteria for optimizing removal of trace organics during land application of municipal wastewater. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 2 van 4 gevonden artikelen
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