Analysis of inlet and outlet industrial wastewater effluents by means of benchtop total reflection X-ray fluorescence spectrometry.

The monitoring of heavy metals in industrial waste water effluents is an important activity in many laboratories. Of special interest is the screening of elemental composition of inlet effluents and quantitative analysis of outlet effluents to study the efficiency of chemical treatment process to eliminate metals and to comply with current established concentration limits, respectively. In this sense, fast analytical methodologies which entail simple sample preparation are desired. In the present work, the possibilities and drawbacks of a benchtop total reflection X-ray fluorescence spectrometer (TXRF) for the rapid and simple determination of some inorganic impurities (As, Ba, Cd, Cu, Cr, Sn, Fe, Mn, Ni, Pb, Se and Zn) in inlet and outlet industrial waste water effluents from metallurgical and tanning leather factories have been tested. An evaluation of different simple sample treatments is presented and it is followed by a discussion of spectral and chemical matrix effects when dealing with this type of samples. Analytical figures of merit such as accuracy, precision and limits of detection have also been carefully studied. Finally, the data obtained by direct TXRF analysis has been compared to that obtained by ICP-OES/ICP-MS after a microwave digestion.

Secondary effluent reclamation: combination of pre-treatment and disinfection technologies.

A study was carried out to evaluate the efficiency of secondary effluent additional treatment, using a combination of pre-treatments (ring filter, physico-chemical and infiltration-percolation) followed by disinfection methods (chlorine dioxide, peracetic acid and ultraviolet light). Three different indicator microorganisms were determined: E. coli, total coliforms and somatic bacteriophages. The results show better efficiency of physico-chemical and infiltration-percolation processes. Bacteriophages were eliminated to a lesser extent than bacterial indicators in all the treatment systems. Chlorine dioxide and peracetic acid seems to be more efficient in disinfection than ultraviolet light when a ring filter is the pre-treatment used. For the same doses and contact times, the efficiency of the disinfection methods is higher when the pre-treatment used is the physico-chemical or the infiltration-percolation system. The final effluent quality from the physico-chemical treatment train and the infiltration-percolation treatment train, followed by the disinfectants, achieves an E. coli content that allows the reuse in most of the uses described in the Spanish legislation for wastewater reuse.

Wastewater reclamation systems in small communities.

The demands established in the rules and regulations by the administration in Catalonia seem to exclude small communities from wastewater reclamation and reuse, due to the comparatively high costs associated with the practice at small scale. In the framework of the DRAC project (Demonstration on Wastewater Reclamation and Reuse in Catalonia) two different pre-treatment systems, one extensive (infiltration-percolation) and another intensive (ring filter), each one followed by chlorine dioxide disinfection, were tested in order to be applied for small communities wastewater reclamation and reuse. The results of this study show that infiltration-percolation systems remove very efficiently physico-chemical contaminants and microorganisms. The ring filter system does not show a significant removal rate of contaminants, The use of infiltration-percolation as a pre-treatment for advanced chemical disinfection allows reducing the dose of disinfectant and the contact time needed to achieve a specific water quality, and diminishes disinfection byproducts (DBPs) generation. Therefore, this reclamation line is suitable for small communities due to its efficiency and low cost. However, further studies are needed in relation to the removal mechanisms of microorganisms, organic compounds in IP systems and the possible DBPs formation using chlorine dioxide.

Biological control tools for wastewater reclamation and reuse. A critical review.

The health related risk of wastewater reclamation and reuse is usually defined by laws, rules or regulations by using only biological tools; i.e. bacteria, viruses, or other pathogens or indicators determination. Those determinations exert some influence in the costs of the mentioned practices, and it seems probable that in the near future more determinations will be required. Nevertheless, a total indication of wastewater biological quality is not given by such organisms; in fact, long-term toxicity is not detected by such means. The future of biological control of reclamation and reuse systems and the price associated to such determinations is examined through a practical application case.