SMOOTH TEMPERATURE DECREASING FOR NITROGEN REMOVAL IN COLD (9-15° C) ANAMMOX BIOFILM REACTOR TESTS

For N-rich wastewater treatment the anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used. In a deammonification moving bed biofilm reactor (MBBR) a maximum total nitrogen removal rate (TNRR) of 1.5 g N m-2d-1(0.6 kg N m-3d-1) was achieved. During biofilm cultivation, temperature was gradually lowered by 0.5° C per week, and a similar TNRR was sustained at 15° C. qPCR analysis showed an increase in Candidatus Brocadia quantities from 5×103 to 1×107 anammox gene copies g-1 TSS despite temperature lowered to 15° C. Fluctuations in TNRR were rather related to changes in influent NH4+ concentration. To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments were performed which showed sufficient TNRRs even at 9-15° C (4.3-5.4 mg N L-1 h-1, respectively) with anammox temperature constants ranging 1.3-1.6. After biomass was adapted to 15° C, the decrease in TNRR in batch tests at 9° C was lower (15-20%) than for biomass adapted to 17-18° C. Our experiments show that a biofilm of a deammonification reactor adapted to 15° C successfully tolerates shortterm cold shocks down to 9° C retaining a high TNRR

Kinetics of extraction and in situ transesterification of oils from spent coffee grounds

Resource limits, environmental concerns and unstable petroleum costs have led to an increased effort to develop alternative liquid fuels. Purpose grown feedstocks are expensive and demand additional resources such as land and water. Spent coffee grounds (SCGs) are a good potential low-cost feedstock, however, processing times and costs must be lowered in order to be cost competitive with fossil fuels. In this work, we investigated the kinetics of oil extraction from SCGs to explore if current methods of oil extraction could be hastened and if an integrated process which couples oil extraction and conversion to biodiesel stages in one single step (in situ transesterification) was viable. Kinetics of oil extraction from SCGs using n-hexane as solvent was studied as a function of temperature, solvent to solid ratio and water content. We have found that oil extraction times could be as low as 10 min due to higher diffusion coefficients of oils from SCGs. Further, we demonstrate, for the first time, the successful in situ transesterification of SCGs using different concentrations of sodium hydroxide as a catalyst and methanol to oil mole ratios. Both of these outcomes show promise for lowering biodiesel production costs from SCGs, a ubiquitous waste product around the world

Autotroofne lämmastikuärastus ja sellega seotud tasakaalulised protsessid

Väitekirja elektrooniline versioon ei sisalda publikatsiooneViimastel aastakümnetel on tehtud ridamisi avastusi, mis on oluliselt täiendanud teadmisi loodusliku lämmastikuringe kohta. Üks olulisemaid neist on reoveepuhastuses kasutatav anammoks-protsess, mis toimub Planctomycetes hõimkonda kuuluvate autotroofsete bakterite vahendusel ja mille käigus ammooniumlämmastik oksüdeeritakse anoksilistes tingimustes, kasutades elektronaktseptorina nitritit. On teada, et teatud osa anammoks-bakterid võivad kasutada peale ammooniumi ka teisi substraate. Käesolevas töös uuriti lämmastikuärastust, kasutades elektronaktseptorina sulfaati. Uuritud tingimustes jäi ärastuse efektiivsus madalaks (ca ¼ lämmastikust) ning protsess oli ebastabiilne. Töö ühe osana teostati autotroofse lämmastikuärastusega pilootseadme käivitamine kolmes erinevas konfiguratsioonis (eraldatud biomudaga nitritatsiooni- ja biokilepõhine anammoks reaktor, vahelduvaeratsiooniga biokilereaktor ja biomudapõhine annuspuhasti). Protsessi aluseks oli ammooniumlämmastiku osalise nitriteerimise kombineerimine konventsionaalse anammoks protsessiga. Protsessi sissevooluna kasutati munitsipaalreoveepuhasti liigmuda anaeroobsel stabiliseerimisel tekkivat eeltöötlemata vädu. Autotroofne lämmastikuärastus käivitus kõikides uuritud reaktorites, parimad tulemused (ärastuskiirus kuni 1 kg-N m–3 d–1) saavutati vahelduvaeratsiooniga biokilereaktoris. Edukas protsessi käivitamine nõuab pH kontrolli (pH<7,5), vaba ammoniaagi kontsentratsiooni jälgimist (< 10 mg-N L–1), aeratsiooni aja- ja hapniku kontsentratsiooni (0,3-0,8 mg-O2 L–1) ning sissevoolu heljumi kontrolli (heljumit < 1000 NTU). Vädu on keerulise koostisega süsteem, mille üksikute komponentide kontsentratsioonid on määratud mitmete pH-st sõltuvate tasakaaluliste protsessidega. Vädu efektiivseks käitluseks on oluline teada selle koostises olevate komponentide kontsentratsioone. Käesolevas töös tuletati matemaatilised mudelid kolmele heterogeensele tasakaalulisele süsteemile: avatud ja suletud süsteemidele CO2–HCO3––CO32––CaCO3 ning suletud süsteemile H2O–CO2–CaCO3–NH4Cl. Kõigile kolmele mudelile teostati eksperimentaalne valideerimine. Mudelite kasutamine võimaldab hinnata konjugeeritud tasakaalulisi protsesse keskkonnas ning leida nendes protsessides osalevate osakeste kontsentratsioone.In recent decades, a couple of discoveries have been made that greatly improve the knowledge of the natural nitrogen cycle. In wastewater treatment, the anammox-process is implemented, where ammonium nitrogen is oxidized under anoxic conditions using bacterial phylum Planctomycetes. In this process, nitrite is used as an electron acceptor. In present work, nitrogen removal by the bacterial consortia containing anammox bacteria under anoxic conditions using sulphate as an electron acceptor was studied. Nitrogen removal involving different groups of bacteria and different metabolic pathways took place, but only in a modest extent, (about ¼ of nitrogen was removed) and the process as a whole was unstable. As part of the work within the scope of the current thesis, the start-up of autotrophic nitrogen removal pilot plant was performed and operated in three different configurations (separated biosludge-based nitritation reactor and biofilm-based anammox reactor; intermittently aerated biofilm reactor; and biosludge-based sequence batch reactor). It was concluded that autotrophic nitrogen removal while treating reject water can be started up independently of applied technological concept, but the best results (nitrogen removal rate up to 1 kg-N m–3 d–1) were achieved in an intermittently aerated biofilm reactor. The critical factors for start-up of a deammonification process are pH control (pH <7.5), free ammonia concentration in reject water (< 10 mg-N L–1), time and concentration-based aeration control (dissolved oxygen 0.3-0.8 mg-O2 L–1) and the control of suspended solids of influent (< 1000 NTU). Reject water is a complex multi-component system. The concentrations of its components are determined by multiple pH-dependent equilibrial processes which are interconnected over protons. In order to ensure efficient and stable treatment of reject water, it is important to know the accurate concentrations of its components. In the present thesis, theoretical mathematical models for three heterogeneous equilibrium systems were derived: for open and closed systems CO2-–HCO3––CO32––CaCO3 and for closed system H2O–CO2–CaCO3–NH4Cl. All three models were experimentally validated. Mathematical models allow to calculate the concentrations of all components in the observed systems and to evaluate the impact of anthropogenic processes on the environment.https://www.ester.ee/record=b5258602~S

Viron kansalaisyhteiskunnan rakentuminen : diskurssin ja instituutioiden kehitys

Construction of Civil Society in Estonia: Discursive and Institutional Changes The dissertation is a study of the emergence of civil society in Estonia on a discursive as well as institutional level. More precisely, I analyse a process which might be called the construction of civil society , i.e., how a new set of knowledge (a new discourse) has appeared in Estonia; and how it has developed and become institutionalised in terms of both form and content. This development has, among other things, been influenced by a transmission of transnational models, but also by structural features of the recipient society. The study s theoretical framework and key concepts rely above all on an approach characteristic for the sociology of knowledge. In explaining Estonian developments and peculiarities, I also analyse the consequences of the rapid transformation that has taken place in the post-Soviet societies. The thesis consists of seven articles and an integrative summary chapter. The articles have been divided into three groups based on subjects: (i) Estonian civil society in its early development, (ii) the consolidation and the problems of civil society in Estonia, and (iii) Estonian civil society in a comparative perspective. I have combined different methods in order to obtain empirical sensitivity: I have studied NGOs through questionnaires and interviews with their representatives as well as through data from the registry. I have conducted in-depth interviews with other social groups or agents who have played an important role in the development of civil society with their specific values, social identities and knowledge of civil society. The use of multi-perspective methods and the theoretical framework of the sociology of knowledge provides the study with new information on the development of civil society in Estonia. It shows the social context in which the construction of civil society started, the main actors, and the special features of civil society in contemporary Estonia. Discursive and institutional developments seem to take place at different pace in different parts of society. This, in turn, has an impact on the domestication and naturalisation of new knowledge. Hence, the outcome may significantly differ from the original transnational model. This asymmetry of discursive and institutional changes causes tension in a society and its power structure. The selective nature of the domestication of transnational models in rapidly changing societies may also explain the differences in how civil society has developed in different post-Socialist countries. Keywords Estonia, civil society, discursive and institutional changes, Project Civil Society, domestication, objectivated knowledgeViron kansalaisyhteiskunnan rakentuminen: diskurssin ja instituutioiden kehitys Väitöskirja käsittelee Viron kansalaisyhteiskunnan kehkeytymistä sekä diskurssin että instituutioiden kannalta. Analysoin kehityskulkua jota voidaan nimittää kansalaisyhteiskunnan rakentumiseksi , eli uuden tiedon (uuden diskurssin) saapumista Viroon sekä sen kehitystä ja institutionalisoitumista niin muodoltaan kuin sisällöltään. Tähän kehitykseen ovat vaikuttaneet sekä ylirajaisten mallien välittyminen Viroon että sen oman yhteiskunnan rakenteelliset ominaisuudet. Tutkimuksen teoreettinen lähtökohta ja keskeiset käsitteet ovat luonteeltaan tiedonsosiologisia. Viron kehityksen ja sen erityispiirteiden selittämiseksi tarkastelen Neuvostoliiton hajoamisen jälkeisten yhteiskuntien nopeaa muutosta. Viimeisen sadan vuoden aikana Viro on toistuvasti kokenut koko yhteiskuntarakenteensa mullistuksen. Tämän vuoksi uuden tiedon ja uusien toimintastrategioiden kehkeytyminen ja institutionalisoituminen ovat siellä selkeämmin nähtävissä kuin vakaamman diskurssijärjestyksen yhteiskunnissa. Väitöskirja koostuu seitsemästä artikkelista ja niitä yhdistävästä yleiskatsauksesta. Artikkelit on aiheidensa mukaan jaettu kolmeen ryhmään: (i) Viron kansalaisyhteiskunnan kehkeytyminen; (ii) sen vakiintuminen ja keskeiset ongelmat; sekä (iii) Viron kansalaisyhteiskunta kansainvälisessä vertailussa. Olen tutkimuksessani käyttänyt erilaisia metodeja: järjestöjä on tutkittu sekä kyselylomakkeiden, haastattelujen että rekisteritietojen avulla. Olen kartoittanut haastatteluissa paitsi järjestöaktiivien, myös toisten kansalaisyhteiskunnan kehitykseen vaikuttaneiden tahojen näkemyksiä. Tutkimus näyttää kansalaisyhteiskunnan rakentumisen yhteiskunnalliset yhteydet, sen tärkeimmät toimijat sekä nyky-Viron kansalaisyhteiskunnan erityispiirteet. Diskurssin ja instituutioiden kehitys näyttää tapahtuvan eri nopeudella yhteiskunnan eri osissa. Sillä puolestaan on vaikutuksensa uuden tiedon vastaanottamiseen ja kotoutumiseen. Lopputulos voi täten huomattavasti poiketa alkuperäisestä ylirajaisesta mallista. Mainittu diskursiivisen ja institutionaalisen kehityksen epäsymmetria synnyttää jännitteitä yhteiskunnassa ja sen valtarakenteissa. Erot siinä, miten kansalaisyhteiskunta on kehittynyt reaalisosialismin jälkeisissä yhteiskunnissa, selittyvät sillä että kansainväliset mallit on omaksuttu valikoivasti. Avainsanat Viro, kansalaisyhteiskunta, diskurssin ja instituutioiden muutos, Project Civil Society, domestication, objektivoitu tiet

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Construction of road embankments in peatlands commonly involves replacement of the peat with a fill-up soil of an adequate load-bearing capacity. This usually requires a lowering of the water level, turning a peatland from a carbon sink to a source of greenhouse gases. Thus, alternatives are sought that are less costly in both economic and ecological terms. Mass-stabilization technology can provide a cheap substitute for Portland cement. Calcareous ashes (waste materials), supplemented with pozzolanic and alkali additives to facilitate and accelerate the setting and hardening processes, are attractive alternatives to soil excavation or replacement techniques. Silica fume and waterglass were used as pozzolanic agents and KOH as a soil-alkalizing agent. X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses and stress–strain tests were performed for the hardened samples. Crystallization of alkali feldspars was observed in all test samples. Comparable hardening of peat soil was achieved for both ashes. It was shown that the ashes of Estonian kukersite (oil shale) from both pulverized firing and a circulating fluidized bed incineration process (produced in energy sector as quantitatively major solid waste in Estonia) can be used as binding agents for peat stabilization, even without the addition of Portland cement. Hardened peat soil samples behaved as a ductile material, and the cellulose fibers naturally present in peat gave the peat–ash composite plasticity, acting mechanically in the same way as the steel or glass fiber in ordinary reinforced concrete. The effect of peat fiber reinforcement was higher in cases of higher load and displacement of the composite, making the material usable in ecological constructions