Polütsüklilste aroomatsete süsivesinikke (PAH-ide) ja raske metallide leostus põlevkivitöötlemise jäätmetest ja põlvekivi jäätmete – põhi nevatest produktidest

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Antud doktoritöö eesmärgiks on põlevkivi termilise töötlemise jäätmete ja põlevkivi töötlemise jäätmetest valmistatud ehitusmaterjalide keskkonnaohtlikkuse hindamine. Põlevkivi suure mineraalaine sisalduse tõttu tekitatakse töötlemise käigus suurtes kogustes tahkeid jäätmeid: termilise töötlemise käigus tekib põlevkivi poolkoks ja põletamisel tekib põlevkivi tuhk, millest taaskasutatakse ainult väike osa. Põlevkivi termilise töötlemise jäätmed sisaldavad ohtlikke raskmetalle ja polütsüklilisi aromaatseid süsivesinikke (PAH-e). Jäätmete keskkonnamõju sõltub pigem saasteainete mobiilsusest, mitte nende sisaldusest lähtematerjalis. Seetõttu saab mõju keskkonnale hinnata vaid läbi aine ülekande tahkest faasist vesifaasi, ehk leostumise abil. Käesolev töö tutvustab leostuvusuuringud väli- ja laboritingimustel. Uuring näitas võimalust hinnata tahkete jäätmete hoidlate keskkonnamõju tõhusa ning odava meetodiga välitingimustes kasutamiseks. Selgus, et poolkoksimäed on ohtlikke PAH-ide ja metallide allikaks pika aja jooksul. PAH-ide leostuvus vanast poolkoksi jäätmehoidlast oli suurem võrreldes hiljuti võetud kasutusele hoidlaga. Töös näidati, et metallide transpordiga keskkonnas võivad olla seotud kolloidid. Uuriti fluoro-PAH-ide (F-PAH-id) kasutust sisestandarditena GC-MS analüüsil. Käesolevas töös uuriti uudse SPME (Solid Phase Microextraction, ehk Tahke Faasi Mikroekstraktsioon) meetodi rakendamist leovee analüüsil. SPME metoodikat kasutati bioloogiliselt kättesaadava (Cfree) PAH-ide fraktsiooni määramiseks. Selgus, et Cfree on väike osa kogu PAH-idest (ainult 0,01-2,7%) leostusvee proovides, mis näitab PAH-ide tugevat seost orgaaniliste ja mineraalainetega. Hinnati PAH-ide ja metallide leostuskäitumist tolmpõletuse ja keevkihtkatla lendtuhast ning tuhast valmistatud mörtidest ja betoonkehadest. Selleks kasutati granuleeritud materjali leostustesti EN 12457-2(2002) ja monoliitse materjali leostustesti EN CEN/TC 15862(2012). PAH-ide sisaldus leovees oli madalam põhjavee keskkonnakvaliteedinäitajatest. Väikese molekulmassiga PAH-ide leostumine leidis aset kõikidest mörtidest ja betoonkehadest, sõltumata tardumisajast. Töö tulemusena saadi väärtusliku infot põlevkivitööstuse tahkete jäätmete ning neist valmistatud produktide käitumise keskkonnas.The largest industrially used oil shale basin in the world is based in Estonia. Due to the high content of mineral matter in oil shale a significant amount of oil shale processing waste is formed. Spent shale – the waste from oil shale retorting, oil shale ash – the waste from oil shale combustion and oil shale processing waste-based products were in¬vestigated in terms of organic and inorganic pollutant leaching (PAHs and metals). The deposit and/or reuse of oil shale processing wastes may be detrimental for both the environment and human health because of entrained organic (polycyclic aromatic hydrocarbons – PAHs) and inorganic (heavy metals) pollutants. In general, the environmental impact of the pollutants is related to their availability for transport and bio-uptake, rather than their total concentrations in waste material. The long-term fate of PAHs and heavy metals in the environment from oil shale processing waste disposal at field conditions was investigated. A simple and effective low-cost field sampling method was used. Results from the present study indicate an increased leachibility of PAHs with time from spent shale deposits, however important to note that their concentrations were low. Although the concentration of PAHs and heavy metals in field leachates were below permissible limits, the spent shale deposit may represent a constant source of low concentrations of potentially hazardous PAHs and metals. The application of fluorinated PAHs as internal standards in GC-MS analysis for PAHs in oil shale wastes was per¬formed. New Solid Phase Microextraction (SPME) method coupled with GC-MS was developed and opti¬mised for determination of the bioavailable fraction of PAHs. Bioavailable fraction (Cfree) of PAH is small, indicating strong association of PAHs with organic and mineral (colloid, clay) matter. Only 0.01–2.7% of total concentration of studied PAHs in the leachate samples comprised for Cfree. A com¬pa¬rative study of the ash and ash-based materials originating from the new cir¬culating fluidized bed combustion (CFB) com-bustion technology and the old pulverized-fired (PF) was conducted. The leaching characteristics from both granular and monolithic waste-based materials were assessed. New method of monolith leaching (CEN/TC 15862, 2012) was applied and performed. The leaching properties of oil shale ash – based material depended on the specific characteristics of ash and hardening time. The obtained results enlarge our knowledge about the environmental pro¬perties of oil shale processing wastes and waste-based materials

Deriving Nutrient Concentrations from Sentinel-3 OLCI Data in North-Eastern Baltic Sea

Nutrients are important elements in marine ecosystems and water quality, and have a major role in the eutrophication of water bodies. Monitoring nutrient loads is especially important for the Baltic Sea, which is especially sensitive to the eutrophication. Using optical remote sensing data in mapping total nitrogen (TN) and total phosphorus (TP) is challenging because these substances do not have a direct influence on the water optics that remote sensing sensors can detect. On the other hand, it would be very rewarding. In this study, more than 25,000 Sentinel-3 Ocean and Land Colour Instrument (OLCI) data algorithms were tested in order to detect the TN and TP concentrations in the Estonian marine waters between 2016–2021. The TN estimations were well derived for Estonian marine waters (R2 = 0.73, RMSE = 4.87 µmolN L−1, MAPE = 14%, n = 708), while the TP estimations were weaker (R2 = 0.38, RMSE = 0.23 µmolP L−1, MAPE = 24%, n = 730). The Estonian marine waters were divided into six geographic regions in order to study the effect of regional water quality on the TN and TP retrievals. The nutrient concentrations were derived in every region when spring and summer periods were treated separately. In this study, the detection of both nutrients was more successful in more closed areas with P deficiency, while in open sea areas it was more challenging. This study shows that it is possible to estimate nutrients, especially TN, from remote sensing data. Consequently, remote sensing could provide a reliable support to the conventional monitoring by covering large marine areas with high temporal and spatial resolution data

Study of Thermooxidation of Oil Shale Samples and Basics of Processes for Utilization of Oil Shale Ashes

A circular economy becomes an object of actual discussions as a real alternative to the existing linear economy system. The problem is actually in Estonia also, first of all in the sector of heat and power production which based mainly on the combustion of local solid fossil fuel—Estonian oil shale (OS) resulting in the formation of ~5–6 million tons of OS ashes annually. The thermooxidative decomposition of OS samples from different deposits and estimation of the possibilities of utilization of OS ashes formed at both—pulverized firing (PF) and circulating fluidized bed combustion (CFBC) of Estonian OS were studied. The thermal analysis combined with evolved gas analysis (EGA) methods like Fourier transform infrared (FTIR) and mass-spectroscopy (MS) was exploited. It was established that the differences in the thermal behaviour of different OS samples are caused by the differences in the chemical matrix of organic matter, chemical and mineralogical composition of the inorganic part of OS, and morphology of samples. It was also found that moderate grinding of OS ashes with simultaneous moderate water treatment notably improved the SO2 binding efficiency of cyclone ash, and that the strength and leachability characteristics of granulated OS ashes strongly depend on the post-granulation treatment conditions allowing to increase the soil neutralizing ability of the granulated products. This overview was based on our investigations carried out during the last fifteen years