Dissertation May 20 - improving water quality
On Friday May 20 Ola Svahn (Kristianstad University) is defending his thesis within Environmental Science, about how to improve the water quality with less pharmaceuticals upgrading treatment plants with a so-called fourth step.
Time and place: 13:00, Naturum, Kristianstad.
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Ola about his research:
When I grew up in the Småland forests around Alvesta me, my brothers and friends spent a lot of time outdoors. We built huts and dam both at possible and impossible places. We always went without a compass, and taught us to find the way home with the help of nature's signs offered by anthills and lichens. I think these childhood experiences amidst nature has greatly contributed to my interest in the environment, and has led me to want to preserve natures values through active work.
The Biosphere Reserve Kristianstads Vattenrike is one out of only five biosphere reserves in Sweden, which is officially recognized by the UN agency UNESCO. Micropollutans as antibiotics and other pharmaceuticals are leeking out into this environment from primearely sewage treatment plants 24 hours a day, seven days a week. Particularly urgent is the effect that follows when compounds are present in a mixture, with the potential to cause a so-called "cocktail effect". New tools, new techniques and better analytical methods are urged for in order to study their fate and effect on the environment. Additionally measures such as advanced wastewater treatment technologies for preventing the leakage from society to environment is of need. Pharmaceuticals are a very inhomgenous group of substances with many different properties including neutrals, acids, bases and zwitterions. These differences make the challenge even greater.
A new technique using a pressurized dynamic flow-through system for studying thermal stability assessment of antibiotics in moderate temperature and subcritical water was developed in this thesis. The design of the system allowed a fast access to a large number of data at medium to subcritical water temperatures, ranging from 50 - 250 °C. The investigated antibiotics showed high degree of stability with a maximum degradation of less than 30% at 150 °C. At 250 °C all antibiotics were either partly of fully removed. This knowledge was important to assure that antibioticas could be extracted from solid samples without being themally degraded. The results also indicated that the heat generated by the digestion processes in a treatment plant process do not affect the stability of antibiotics over a short time period.
A chromatographic system with on-line detection was developed to perform sorption studies of six selected pharmaceuticals with differing physicochemical characteristics to four natural sediments and dewatered digested sewage treatment plant sludge. Sorption effects, measured as asymmetry factors and recoveries, differed pronouncedly among the pharmaceuticals and between the matrices, which could be explained by basic physicochemical properties of the investigated compounds in relation to matrix characteristics. Protonated and deprotonated molecular properties had the greatest importance for sorbate–sorbent interactions. The matrix content of organic matter measured as total organic carbon (TOC) clearly dictated drug sorption. Beside from studying matrix interaction, these results and the developed technique and methodology might find use in the development of new removal processes of pharmaceuticals from wastewater based on improved knowledge concerning chemical interactions to filter materials.
The majority of analyzes in environmental analytical chemistry performed during the last 30 years, has been carried out at a pH adjusted to the acidic side. This ingrained behavior is challenged in this thesis. By performing fundamental exploration of the ESI positive mode the full potential of a multi-component UPLC-MS/MS-system, adapted to analyze antibiotic and drug residues with widely different properties could be utilized. The underlying hypothesis is that by examining chemical compounds in regard to chromatographic and mass spectrometric preferences, without historical prejudice, better conditions are created. This reduces the element of compromise in the performance of the analytical separation and detection. Our data strongly supports the questioning of the assumption that equilibrium concentrations of ions in solution reflect those produced during the electrospray process. ESI responses of [M+H]+ and limits of detection were comparable, or often better at high pH compared to acidic eluents. Presence of nitrogen basic groups such as tertiary and secondary amines in a compound increased the intensity of the ESI+ signal, and was even further elevated in basic eluent. The proton affinity probably changes for many nitrogen-containing compounds during the ionization process, making the gas-phase processes very important in generation of these ions by ESI+. It was showed that the develpoed UPLC-MS/MS method, including a simple optimization protocol, is cabale of analysing both known micropollutants as well as those yet to be discovered as environmental contaminants.
To improve the degree of purification of the micropollutants in sewage treatment plants of today, there is a potential of upgrading treatment plants with a so-called fourth step as investigated in this work. A full scale pilot plant, based on activated carbon, filtering 2 m3 effluent water/hour, was evaluated with the above described analytical method. The filter showed very robust performance and the filtering of 2500 m3 cubic water showed a nearly 100% removal rate of the measured pharmaceuticals.