Organic contaminants present in the water are not eliminated properly in treatment plants. These contaminants gradually build up in the places where the treated water is discharged, and also in the compost obtained from the sludge produced in the treatment process. UPV/EHU researchers have developed new analytical methods to determine compounds in water from treatment plants, in compost obtain from the sludge and in plants grown in soils fertilised by this compost that may affect the endocrine system.

The aim of wastewater treatment plants is to treat urban and industrial wastewater and return it to the environment once it has been treated. Another of the products obtained in the treatment plants is sludge; this is usually treated and turned into compost or incinerated -among other treatments-. In any case, the treatment plants are not designed to eliminate all the contaminants. Specifically, organic contaminants are not properly eliminated; they slowly accumulate in the places where the wastewater is discharged and the compost produced using treatment plant sludge may end up becoming a source of contaminants.

The researcher Arantza Iparraguirre, of the IBeA research group of the Department of Analytical Chemistry of the UPV/EHU's Faculty of Sciences and Technology, has developed various analytical methods that are effective in establishing and quantifying organic contaminants that may affect the endocrine system in treated wastewater, in soil fertilised with compost that has come from the treatment plant sludge, and in plants grown in these soils. Organic contaminants that hamper hormonal functioning are known as endocrine disruptors and they can be harmful for certain physiological processes controlled by hormones. Among other things, they intervene in the growth of organisms, in their behaviour, in their reproduction and in their immune function.

If these contaminants are to be eliminated in the future, they need to be specified and quantified beforehand. The analytical methods that Iparraguirre has developed in her PhD thesis are highly sensitive ones, in other words, they are capable of detecting very small concentrations. This is due to the fact that endocrine disruptors are found in very low concentrations in environmental samples. It is worth pointing out that endocrine disruptors may have adverse effects even at very low concentrations. On the other hand, some of the methods developed for analysing treated water are related to green chemistry. The last few years have seen the predominance of the trend in developing methods that harm the environment as little as possible. In line with this trend, the researcher has developed specification methods that use the lowest possible quantity of organic solvents and methods that use no organic solvents.

In order to recycle the sludge produced by treatment plants, compost is produced and used to fertilise soil. This research concluded that this compost contains organic contaminants. However, carrots have been grown in soil using this compost and in the conditions used in the research the organic contamination was not found to have reached the vegetables. However, the researcher explained that in the research very specific conditions were used so "it could happen that with higher concentrations of contaminants in the soil, the contamination could reach the vegetables".

The legislation will have to be amended first

Many contaminating components are legislated by the EU's Water Framework Directive and the risks they entail are known. For other contaminants, however, the legislation has yet to specify anything concrete, although there could be doubts as to whether they are harmful. Treatment plants comply with protocols to determine and eliminate certain compounds in wastewater (above all metals) in line with the legislation in force; so, first of all, the legislation would need to be amended to incorporate organic contaminants into these protocols.

But there is still so much more on which to conduct research, and what is more, to eliminate these contaminants the treatment plants would need to be fitted with specific equipment. A first step would be to install suitable equipment to determine and quantify organic compounds in the laboratories of the treatment plants; in other words, one would have to start monitoring these compounds in a systematic way. "It isn't that straightforward. Organic compounds are determined using specific equipment, using chromatographs," explained Iparraguirre. And once the quantification protocols of these contaminants have been specified, one would need to come up with and develop new effective elimination treatments".

Additional information

Arantza Iparraguirre-Izaga (Igorre, Basque Country, 1986) is a graduate in Chemistry and has a Master's in Environmental Contamination and Toxicology. She wrote up her PhD thesis Development of novel analytical methods for the determination of endocrine disrupting compounds in wastewater, amended soil and vegetables at the Department of Analytical Chemistry of the UPV/EHU's Faculty of Science and Technology under the supervision of the tenured lecturer Olatz Zuloaga-Zubieta.

References:

A. Iparraguirre, P. Navarro, R. Rodil, A. Prieto, M. Olivares, N. Etxebarria, O. Zuloaga. "Matrix effect during the membrane-assisted solvent extraction coupled to liquid chromatography tandem mass spectrometry for the determination of a variety of endocrine disrupting compounds in wastewater". Journal of Chromatography A, (2014) 1356:163-170. DOI 10.1016/j.chroma.2014.06.051

A. Iparragirre, R. Rodil, J.B. Quintana, E. Bizkarguenaga, A. Prieto, O. Zuloaga, R. Cela, L.A. Fernández. "Matrix solid-phase dispersion of polybrominated diphenyl ethers and their hydroxylated and methoxylated analogues in lettuce, carrot and soil". Journal of Chromatography A, (2014) 1360:57-65. DOI 10.1016/j.chroma.2014.07.079

A. Iparraguirrea, A. Prieto, A. Vallejo, M. Moeder, L.A. Fernandez, O. Zuloaga, A. Paschke. "Tetraphasic polar organic chemical integrative sampler for the determination of a wide polarity range of organic pollutants in water. The use of performance reference compounds and in-situ calibration". Sent for publication.

Image: Arantza Iparragirre

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