Land Application of Wastewater in Brazil - A scientific challenge: Chemical Characterization of Soil at Populina, São Paulo State (9 pp)

The rapid increase of wastewater worldwide and the consequently urgently needed treatment measures towards disposal purposes has led to an expansion of alternative treatment methods. Besides conventional and cost intensive systems, domestic wastewater treatment by overland flow process represents an...

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Bibliographic Details
Published in:Journal of soils and sediments 2005-06, Vol.5 (2), p.112-120
Main Authors: Rosolen, V, Herpin, U, Fraenzle, S, Breulmann, G, de Camargo, P B, Paganini, W S, Cerri, C C, Melfi, A J, Markert, B
Format: Article
Language:English
Subjects:
Chemical elements
Grain size
Soils
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Summary:The rapid increase of wastewater worldwide and the consequently urgently needed treatment measures towards disposal purposes has led to an expansion of alternative treatment methods. Besides conventional and cost intensive systems, domestic wastewater treatment by overland flow process represents an effective and low-cost alternative. However, in addition to beneficial elements in wastewaters, there is a release of other elements of the Periodic Table into the environment, which can be considered as potentially toxic. This requires a reliable chemical characterization of the wastewater element composition as well as the soils onto which it will be applied. This paper aims at presenting the chemical fingerprint methodology to characterize concentrations of a large set of elements in a tropical ferralsol in order to provide information concerning chemical modifications after long-term application of wastewater by overland flow process. The results are also used to estimate environmental implications according to guiding values for soils in Sao Paulo State. The wastewater treatment in Populina has been operating for 18 years. Composite soil samples were taken in a treated plot and a control plot. Wastewater was chemically characterized by using AAS. Total C and total N of soil samples were determined by Delta Plus Mass Spectrometer. The remaining elements (32) were analyzed using ICP-OES. Grain size analysis was carried out after oxidation by H202, and soil dispersion with NaOH and Na4P2O7 treatments. pH was measured in water. Quality control of all measurements was verified by corresponding reference materials. Fingerprint graphs were generated by standardizing the values of the control plot and by graphically displaying positive/negative percentage deviations of the element values at the treated plot from values of the control site. Chemical analyses of the wastewater used showed high BOD, COD, TOC and N values, while the majority of metals were below the detection limit that is attributed to the limitations in the instrumental techniques (AAS) utilized. The comparison of the two selected sites revealed substantial changes of the element contents associated with long-term application of domestic wastewater. Fingerprint graphs of the treated field indicated higher values for the vast majority of macro and micro-nutrients (C, N, P, K, Ca, Mg, Mo, Zn, Cu), as well as for other elements, e.g. Ba, Sr, Na, Li, or La. Enrichments of ecotoxic elements (e.g. As or P
ISSN:1439-0108
1614-7480
DOI:10.1065/jss2005.05.137