Analyses of heavy metals in sewage and sludge from treatment plants in the cities of Campinas and Jaguariúna, using synchrotron radiation total reflection X-rayfluorescence

Abstract

A major consequence of accelerated urban and industrial development in the last decades is water pollution. In particular, metal contamination is a significant problem, causing serious changes to the environment and adversely affecting human health. The cities of Campinas and Jaguariúna are inserted in the Campinas Metropolitan Region (CMR), one of the most dynamic regions in the Brazilian economy, accounting for 2.7% of Gross National Product (GNP) and 7.83% of São Paulo State Product—or approximately $ 70.7 billion per year. Besides having a strong economy, the region also presents an infrastructure that provides the development of the entire metropolitan area. Therefore, to study the anthropogenic influences of the cities, the evaluation of the quality of raw and treated effluent and, the sludge generated in sewage treatment plants (STP), especially with regard to heavy metals was performed by Total Reflection X-Ray Fluorescence with Synchrotron Radiation technique. The results were compared with the allowed values established by Brazilian Legislation. For raw and treated effluents collected in Jaguariúna and Campinas city in the Stations of Treatment of Sewage (Camanducaia and Anhumas), Cr presented higher concentrations than the maximum allowed values established by CONAMA 357. However, it is necessary to do other studies to define the fraction of Cr⁺³ and Cr⁺⁶ to compare to the new legislation. The other elements were in agreement with established regulations. For sludge sampled in the same locations, the concentrations of Cr, Cu, Pb, Ni and Zn were compared with the CONAMA 375 and showed values smaller than the maximum allowed values, indicating the possibility to re-use the sludge.

Introduction

The lack of planning of city growth is, today, one of the major causes of river pollution. Often, growth happens in the most disorderly and unreasonable ways. Among the types of pollution found throughout the world, water pollution is considered a serious threat to the environment because it involves several forms of waste including residential, industrial, agricultural, and hospital (Moreira and Fazza, 2008).

This study is based on concern for the depletion and degradation of natural resources. Contaminations of water resources due to anthropogenic actions present a picture of imbalance. The treated wastewater can be discarded in the water bodies directly and/ or reused. The sludge generated at sewage treatment plants, is an important source of nutrients and organic matter, and therefore it can also be reused mainly for agricultural use, since contaminants are removed.

Therefore, the main objective of this study was to evaluate the quality of the raw effluent treated and the sludge from the sewage treatment plants (STP) of Jaguariúna (STP Camanducaia) and Campinas (STP Anhumas).

With the goal of applying treated effluent for reuse and even a possible application of sludge for agricultural uses, were determined potentially toxic elements using X-ray fluorescence by total reflection with synchrotron radiation (SR-TXRF) (Bertoncini and Mattiazzo, 1999, Bettiol et al., 1983).

SR-TXRF was used in this study because of the small sample size that was required and for its sensitivity to detect very low concentrations (Klockenkamper, 1997).