Minimização do impacto ambiental do processo de curtume de pele de bovino

O presente trabalho teve como objectivo a minimização do impacto ambiental do processo de curtume da pele de bovino. A indústria de curtumes transforma a pele, material putrescível, em couro, material nobre, termicamente estável e imputrescível. A transformação da pele em couro origina uma carga poluente apreciável quer quanto a efluentes líquidos quer quanto a resíduos sólidos. O fluxo produtivo da indústria de curtumes pode dividir-se em quatro sectores: ribeira, curtume, tinturaria e acabamento, sendo que os três primeiros geram efluentes líquidos com elevada carga poluente. Neste trabalho, foram avaliadas as fases do processo que geram efluentes líquidos: molho, caleiro, curtume e tinturaria. Na avaliação do processo do molho testou-se uma protease e uma lipase contra um molhante e um desengordurante tradicional, agentes químicos normalmente utilizados no molho mas menos biodegradáveis que as enzimas testadas. Salienta-se o bom resultado obtido quanto à eficiência do molho Na avaliação do processo de caleiro testaram-se várias alternativas no sentido da redução da quantidade de sulfureto de sódio utilizada e da minimização da carga poluente. Entre as alternativas, depilação por oxidação, depilação enzimática com e sem destruição do pêlo, elegeu-se a depilação enzimática sem destruição do pêlo que conduziu a resultados com menor impacto ambiental, nomeadamente a redução da % da quantidade de sulfureto de sódio, sendo a redução da carga poluente de 4,19 % de sulfureto, 32.80% de sólidos suspensos totais (SST),27.09% de sólidos totais (ST) e de 76.90% da carência química de oxigénio (CQO) no efluente de caleiro. No processo do curtume da pele é utilizado crómio como agente de curtume em cerca de 80% das peles tratadas, sendo este metal problemático em termos ambientais. No sentido de reduzir a quantidade de crómio utilizada no processo foi realizado um planeamento factorial onde as variáveis a estudar foram a concentração de crómio e a temperatura, tendo este como objectivo observar qual a quantidade mínima de crómio necessária para termos um produto final nas condições desejadas e gerando um menor impacto ambiental. Concluiu-se desenvolvendo um processo que mostra ser possível reduzir a quantidade de sal de crómio de 7% para 5%, além de ter um impacto ambiental claramente menos agressivo nos efluentes de curtume gerado. Este processo quando comparado com o processo tradicional permite a redução de 27% na CQO, 79% nos SST, 11% nos ST e 38% no teor de crómio Na avaliação do processo de tinturaria foi estudado um processo compacto contra o processo tradicional, tendo-se concluído pelo menor impacto ambiental do processo estudado, nomeadamente ao nível da redução do consumo de água e da carga poluente gerada. A comparação dos dois processos, no que respeita à carga poluente gerada, permitiu concluir por uma redução de 39% da CQO, 50% dos SST, e 12% dos ST quando aplicado o processo compacto Por fim foi feita uma avaliação do impacto ambiental do efluente global gerado pelos processos considerados com menor impacto ambiental contra o processo tradicional, normalmente aplicado na indústria. A aplicação do conjunto dos processos desenvolvidos, quando comparada com a aplicação do conjunto dos processos tradicionais, mostra uma redução de 1% no sulfureto, 40% na CQO, 60 % nos SST, 42 % no crómio e 11% nos ST, mostrando claramente que é possível reduzir a carga poluente da indústria de curtumes atuando no processo. Este trabalho mostrou a importância de atuar no processo para minimizar os custos de tratamento e mesmo de investimento dos efluentes da indústria de curtumes. Importa salientar que os processos desenvolvidos necessitam de validação a uma escala semi-industrial.

Deeper insights into SRB-driven biocorrosion mechanisms

Dissertação para obtenção do Grau de Doutor em Química Sustentável

Assessment of hydrogen sulfide removal from biogas using a field scale anoxic biotrickling filter.

Hydrogen sulphide is one of the most toxic and corrosive compound present in swine-derived biogas streams.In this study, afield scale biotrickling filter for the removal of hydrogen sulfide was investigated.A Biofilter packed with supporting biofilm materials was fed continuously with a proprietary nutrient solution and operatedfor over 73days. The system has been operating with a H2S inlet concentrations ranging from 1,000to 3,000 ppm.Significant removal efficiencies >95% was demonstrated. pH of the stock feeding solution decreased from 6.2 to as low as 3.5within couple days.The resulting drop in pH provided circumstantial evidence to support biological H2 Soxidation to sulphuric acid by sulfide-oxidizers. Sulfur precipitation was also observed to occur. The results suggested that H2S removal from biogas stream can be efficiently achieved using portable, low cost and maintenance free biotrickling filters.

Methanogens, sulphate and heavy metals: a complex system

Anaerobic digestion (AD) is a well-established technology used for the treatment of wastes and wastewaters with high organic content. During AD organic matter is converted stepwise to methane-containing biogasa renewable energy carrier. Methane production occurs in the last AD step and relies on methanogens, which are rather sensitive to some contaminants commonly found in wastewaters (e.g. heavy metals), or easily outcompeted by other groups of microorganisms (e.g. sulphate reducing bacteria, SRB). This review gives an overview of previous research and pilot-scale studies that shed some light on the effects of sulphate and heavy metals on methanogenesis. Despite the numerous studies on this subject, comparison is not always possible due to differences in the experimental conditions used and parameters explained. An overview of the possible benefits of methanogens and SRB co-habitation is also covered. Small amounts of sulphide produced by SRB can precipitate with metals, neutralising the negative effects of sulphide accumulation and free heavy metals on methanogenesis. Knowledge on how to untangle and balance sulphate reduction and methanogenesis is crucial to take advantage of the potential for the utilisation of biogenic sulphide as a metal detoxification agent with minimal loss in methane production in anaerobic digesters.

Sulphate-reducing bacteria associated with biocorrosion: a review

Biocorrosion means any process of corrosion in wich microorganisms are somehow involved. As far as the petroleum industry is concerned, the anaerobic type is the more important, with Sulphate-Reducing Bacteria (SRB) accouting for half of the described processes. SRB are obligate anaerobs that use sulphur, sulphate or other oxidized sulphur compounds as oxidizing agents when decomposing organic material. A typical product of SRB metabolism, hydrogen sulphide -H2S-, is extremely toxic. In the present work we review the literature on mechanisms underlying biocorrosive process in wich SRB are involved and summarize some of the ultrastructural and eletrochemical work developed using SRB obtained from water injection flow in wells located on PETROBRAS offshore marine plataforms, sampled directly in the field over metallic probes, or cultured under laboratory conditions. Biofilms develop when SRB adhere to inert surfaces. A high diversity of morphological types is found inside these biofilms. Their extracellular matrix is highly hydrated and mainly anionic, as shown by its avid reaction with cationic compounds like ruthenium red. We have noted that variations in iron contet lead to interesting changes in the ultrastructure of the bacterial cell coat and also in the rate of corrosion induced in metallic test cupons. Since routine methods to prevent and treat SRB contamination and biodeterioration involve the use of biocides that are toxic and always have some environmental impact, an accurate diagnosis of biocorrosion is always required prior to a treatment decision. We developed a method that detects and semi-quantifies the presence of living or dead SRB by using free silver potentials as an indicator of corrosive action by SRB-associated sulphides. We found a correlation between sulphide levels (determined either by spectrophotometry, or using a silver electrode -E(Ag)- that measured changes in free potentials induced by the presence of exogeneously added sulphide) and SRB concentration (enumerated by a culturing method). E (Ag) was characterized under a variety of conditions andwas found to be relatively immune to possible interference resulting from aeration of media or from the psence of iron corrosion products. The method offers a simple, rapid, and effective means of diagnosing biocorrosive processes prior to their control.

Geological setting of the Guelb Moghrein Fe oxide-Cu-Au-Co mineralization, Akjoujt area, Mauritania

The Guelb Moghrein Fe oxide-Cu-Au-Co deposit is located at the western boundary of the West African craton in NW Mauritania. The wall rocks to the mineralization represent a meta-volcanosedimentary succession typical of Archaean greenstone belts. Two types of meta-volcanic rocks are distinguished: (1) volcanoclastic rocks of rhyodacite-dacite composition (Sainte Barbe volcanic unit), which form the stratigraphic base; (2) tholeiitic andesites-basalts (Akjoujt meta-basalt unit). The trace element signature of both types is characteristic of a volcanic arc setting. A small meta-pelitic division belongs to the Sainte Barbe volcanic unit. A meta-carbonate body, which contains the mineralization, forms a tectonic lens in the Akjoujt meta-basalt unit. It can be defined by the high X(mg) (=36) of Fe-Mg carbonate, the REE pattern and the delta(13)C values of -18 to -17 parts per thousand as a marine precipitate similar to Archaean banded iron formation (BIF). Additionally, small slices of Fe-Mg clinoamphibole-chlorite schist in the meta-carbonate show characteristics of marine shale. This assemblage, therefore, does not represent an alteration product, but represents an iron formation unit deposited on a continental shelf, which probably belongs to the Lembeitih Formation. The hydrothermal mineralization at 2492 Ma was contemporaneous with regional D(2) thrusting of the Sainte Barbe volcanic unit and imbrications of the meta-carbonate in the upper greenschist facies. This resulted in the formation of an ore breccia in the meta-carbonate, which is enriched in Fe, Ni, Co, Cu, Bi, Mo, As and Au. Massive sulphide ore breccia contains up to 20 wt% Cu. The ore fluid was aqueous-carbonic in nature and either changed its composition from a Mg-rich oxidizing to an Fe-rich reducing fluid or the two fluid types mixed at the trap site. All lithologies at Guelb Moghrein were deformed by D(3) thrusting to the east in the lower greenschist facies. The mobility of REE in the retrogressed rocks explains the formation of a second generation of hydrothermal monazite, which was dated at c. 1742 Ma. Archaean rocks of the West African craton extend to the west to Guelb Moghrein. The active continental margin was deformed and mineralized in the Late Archaean-Early Proterozoic and again reactivated in the Mid-Proterozoic and Westphalian, showing that the western boundary of the craton was reactivated several times.

Pharmacotherapy and analysis of gaseous mediators in hypertensive patients

OBJECTIVE To evaluate the effect of using antihypertensive classes of drugs of the calcium channel antagonists and inhibitors of angiotensin-converting enzyme in plasma concentrations of hydrogen sulfide and nitric oxide in patients with hypertension. METHODS Cross-sectional study with quantitative approach conducted with hypertensive patients in use of antihypertensive classes of drugs: angiotensin-converting enzyme inhibitors or calcium channel antagonists. RESULTS It was found that the concentration of plasma nitric oxide was significantly higher in hypertensive patients that were in use of angiotensin-converting enzyme inhibitors (p<0.03) and the hydrogen sulphide concentration was significantly higher in hypertensive plasma in use of calcium channel antagonists (p<0.002). CONCLUSION The findings suggest that these medications have as additional action mechanism the improvement of endothelial dysfunction by elevate plasma levels of vasodilatory substances.

Serial protein labeling with infrared maleimide dyes to identify cysteine modifications

Cysteine thiol modifications are increasingly recognized to occur under both physiological and pathophysiological conditions, making their accurate detection, identification and quantification of growing importance. However, saturation labeling of thiols with fluorescent dyes results in poor protein recuperation and therefore requires the use of large quantities of starting material. This is especially important in sequential dye-labeling steps when applied for an identification of cysteine modifications. First, we studied the effects of different detergents during labeling procedure, i.e. Tween 20, Triton X-100 and CHAPS, on protein yield and composition. Tween 20 and Triton X-100 resulted in yields of around 50% labeled proteins compared to only 10% with PBS alone and a most diversified 2-DE protein pattern. Secondly, Tween 20 was used for serial protein labeling with maleimid fluorophores, first to conjugate to accessible thiols and after a reduction to label with another fluorophore previously masked di-sulphide and/or oxidized proteins in frontal cortex autopsy tissue of a subject with mild Alzheimer's disease. Two-DE DIGE revealed a complex protein pattern of readily labeled thiols and di-sulphide and/or oxidized proteins. Seventeen proteins were identified by MALDI-TOF and by peptide fingerprints. Several proteins were oxidized and involved in Alzheimer's disease. However methionine oxidation was prevalent. Infrared DIGE may provide an additional tool for an identification of oxidation susceptible proteins.

Application de nanoparticules luminescentes pour la detection de traces papillaires

Après avoir situé le contexte de la recherche et défini les enjeux principaux du travail, différents types de nanoparticules, ainsi que leurs principales caractéristiques, sont parcourues. L'élaboration de critères de sélection ayant permis de déterminer les types de nanoparticules potentiellement adaptés à !a détection de traces papillaires, l'étude s'est alors focalisée sur deux familles de composés: les quantum dots et les nanoparticules d'oxyde de silicium. Deux types de quantum dots ont été synthétisés : le tellurure de cadmium et le sulfure de zinc). Ils n'ont toutefois pas permis la détection de traces papillaires réalistes. En effet, seules des traces fraîches et enrichies en sécrétions ont pu être mises en évidence. Toutefois, des résultats ont été obtenus avec les deux types de quantum dots pour la détection de traces papillaires sanglantes. Après optimisation, les techniques rivalisent avec les méthodes couramment appliquées en routine. Cependant, l'interaction se produisant entre les traces et les nanoparticules n'a pas pu être déterminé. Les nanoparticules d'oxyde de silicium ont dès lors été appliquées dans le but de comprendre plus en détails les interactions avec les traces papillaires. Ces nanoparticules ont l'avantage d'offrir un très bon contrôle de surface, permettant ainsi une étude détaillée des phénomènes en jeu. Des propriétés de surface variables ont dès lors été obtenues en greffant diverses molécules à la surface des nanoparticules d'oxyde de silicium. Après avoir exploré différentes hypothèses d'interaction, il a pu être déterminé qu'une réaction chimique se produit lors qu'un groupement de type carboxyle est présent à la surface des particules. Ce groupement réagit avec les fonctions amines primaires des sécrétions. L'interaction chimique a ensuite pu être renforcée par l'utilisation d'un catalyseur, permettant d'accélérer la réaction. Dans la dernière partie du travail, les nanoparticules d'oxyde de silicium ont été comparées à une technique utilisée en routine, la fumigation de cyanoacrylate. Bien que des études plus approfondies soient nécessaires, il s'avère que l'application de nanoparticules d'oxyde de silicium permet une détection de très bonne qualité, moins dépendante du donneur que les techniques courantes. Ces résultats sont prometteurs en vue du développement d'une technique possédant une sensibilité et une sélectivité accrue. - Having situated the background of research and identified key issues of work, different types of nanoparticles and their main features are reviewed. The development of selection criteria lead to the identification of nanoparticles types potentially suitable for fingermarks detection. The study focused then On two families of compounds: quantum dots and silicon oxide nanoparticles. Two types of quantum dots were synthesized and characterised: cadmium telluride and zinc sulphide. Unfortunally, they did not allow the detection realistic fingermarks. Indeed, only fresh and groomed fingermarks have been detected. However, results have been obtained with both types of quantum dots for the detection of fingermarks in blood. After optimization procedures, the quantum dots based teshniques compete with the methods currently used in routine. However, the interaction occurring between fingermarks and nanoparticles could not be determined. Silicon oxide nanoparticles have therefore been applied in order to understand in detail the interactions With fingermarks. These nanoparticles have the advantage of providing a very good surface control, allowing am in-depth study of the phenomena involved. Versatile surface properties were therefore obtained by grafting various molecules on the surface of silicon oxide nanoparticles. Different hypotheses were investigated and it was determined that a chemical reaction occurred between the surface functionalised nanoparticles and the fingermark residues. The carboxyl groups on the surface of the particles react with primary amines of the secretions. Therefore, this interaction was improved by the use of a catalyst. In the last part of the work, silicon oxide nanoparticles were compared to a routinely used technique: cyanocrylate fuming. Although further studies are still needed, it appears that the application of silicon oxide nanoparticles allows fingermark detection of very good quality, with a lowered donor dependency. These results are promising for the development of techniques with greater sensitivity and selectivity.

Origin of siderite mineralisation in Petrova and Trgovska Gora Mts., NW Dinarides

The Petrova and Trgovska Gora Mts. (Gora=Mountain) are Variscan basement units incorporated into the northwestern Dinarides during the Alpine orogeny. They host numerous siderite-quartz-polysulphide, siderite-chalcopyrite, siderite-galena and barite veins, as well as stratabound hydrothermal-replacement ankerite bodies within carbonates in non-metamorphosed, flysch-like Permo-Carboniferous sequences. The deposits have been mined for Cu, Pb, Ag and Fe ores since Medieval times. Fluid inclusion studies of quartz from siderite-polysulphide-quartz and barite veins of both regions have shown the presence of primary aqueous NaCl-CaCl(2)+/- MgCl(2)-H(2)O +/- CO(2) inclusions. The quartz-sulphide stage of both regions show variable salinities; 2.7-26.2 wt% NaCl eq. for the Trgovska Gora region and 3.4-23.4 wt% NaCl eq. for the Petrova gora region, and similar homogenisation temperatures (100-230A degrees C). Finally, barite is precipitated from low salinity-low temperature solutions (3.7-15.8 wt % NaCl equ. and 115-145A degrees C). P-t conditions estimated via isochore construction yield formation temperatures between 180-250A degrees C for the quartz-sulphide stage and 160-180A degrees C for the barite stage, using a maximum lithostatic pressure of 1 kbar (cc. 3 km of overburden). The sulphur isotope composition of barite from both deposits indicates the involvement of Permian seawater in ore fluids. This is supported by the elevated bromium content of the fluid inclusion leachates (120-660 ppm in quartz, 420-960 ppm in barite) with respect to the seawater, indicating evaporated seawater as the major portion of the ore-forming fluids. Variable sulphur isotope compositions of galena, pyrite and chalcopyrite, between -3.2 and +2.7aEuro degrees, are interpreted as a product of incomplete thermal reduction of the Permian marine sulphate mixed with organically- and pyrite-bound sulphur from the host sedimentary rocks. Ore-forming fluids are interpreted as deep-circulating fluids derived primarily from evaporated Permian seawater and later modified by interaction with the Variscan basement rocks. (40)Ar/(39)Ar data of the detrital mica from the host rocks yielded the Variscan age overprinted by an Early Permian tectonothermal event dated at 266-274 Ma. These ages are interpreted as those reflecting hydrothermal activity correlated with an incipient intracontinental rifting in the Tethyan domain. Nevertheless, 75 Ma recorded at a fine-grained sericite sample from the alteration zone is interpreted as a result of later resetting of white mica during Campanian opening/closure of the Sava back arc in the neighbouring Sava suture zone (Ustaszewski et al. 2008).

Cadmium-free quantum dots in aqueous solution: potential for fingermark detection, synthesis and an application to the detection of fingermarks in blood on non-porous surfaces

The use of quantum dots (QDs) in the area of fingermark detection is currently receiving a lot of attention in the forensic literature. Most of the research efforts have been devoted to cadmium telluride (CdTe) quantum dots often applied as powders to the surfaces of interests. Both the use of cadmium and the nano size of these particles raise important issues in terms of health and safety. This paper proposes to replace CdTe QDs by zinc sulphide QDs doped with copper (ZnS:Cu) to address these issues. Zinc sulphide-copper doped QDs were successfully synthesized, characterized in terms of size and optical properties and optimized to be applied for the detection of impressions left in blood, where CdTe QDs proved to be efficient. Effectiveness of detection was assessed in comparison with CdTe QDs and Acid Yellow 7 (AY7, an effective blood reagent), using two series of depletive blood fingermarks from four donors prepared on four non-porous substrates, i.e. glass, transparent polypropylene, black polyethylene and aluminium foil. The marks were cut in half and processed separately with both reagents, leading to two comparison series (ZnS:Cu vs. CdTe, and ZnS:Cu vs. AY7). ZnS:Cu proved to be better than AY7 and at least as efficient as CdTe on most substrates. Consequently, copper-doped ZnS QDs constitute a valid substitute for cadmium-based QDs to detect blood marks on non-porous substrates and offer a safer alternative for routine use.

Nauhasuodatukseen vaikuttavien parametrien tutkiminen

Nauhasuodattimia käytetään teollisuuden aloilla, joissa suodatettavan suspension määrä vaihtelee laajalti ja suodinkakun peseytyminen on tärkeää. Oikean kangasrakenteen valinnalla voidaan kasvattaa suodatuskapasiteettia ja parantaa suodatustulosta. Tämän diplomityön tavoitteena oli tutkia metallisulfidisakan nauhasuodatukseen liittyviä parametreja suodatuksen parantamiseksi. Tavoitteena oli löytää sopiva kangas ja ajoparametrit kloridin pesemiseksi suodinkakusta mahdollisimman tarkasti ja samalla säilyttää hyvä suodospuhtaus. Suodatuskapasiteetin kasvattaminen oli myös toivottavaa. Kirjallisuusosassa keskityttiin kakkusuodatuksen teoriaan, nauhasuodatukseen ja tutustuttiin hieman nauhasuodatukseen liittyvään laskentaan. Uusia kehitteillä olevia suodatusta parantavia menetelmiä käsiteltiin myös kirjallisuusosassa. Kokeellisessa osassa tutkittiin koesuunnittelua hyväksi käyttäen metallisulfidisakan suodatukseen vaikuttavienparametrien vaikutusta. Testattavia parametreja olivat mm. alipaine, lietteen kiintoainepitoisuus, syötön ja pesuveden määrä. Kokeet osoittivat, että kankaan rakenteella ei ole suurta vaikutusta pesutulokseen. Pesuilla ei myöskään voida kokonaan poistaa suodinkakussa olevaa kloridia. Tulosten perusteella kokeissa käytetyillä kudotuilla kankailla päästiin yhtä hyviin kuin huopakankaalla. Suodattimen toiminnan kannalta paras tilanne on, jos suodattimelle tulevan lietteen kiintoainepitoisuus pysyy melko vakiona. Suodattimella käytettävän kankaan käyttöikää kasvattaa kankaan hyvä kulutuskestävyys, kakun irtoaminen helposti kankaan pinnalta ja kankaan pysyminen huokoisena kankaan pesujen ansiosta.

Selvityksiä reaktiokalorimetrin soveltuvuudesta hydrometallurgiaan

Tämän työn tavoitteena oli reaktiokalorimetrin käyttöönotto sekä sen käyttökelpoisuuden selvittäminen hydrometallurgisten sovellusten ja erityisesti sinkkisulfidin liuotuksen tutkimiseen. Työn kirjallisuusosassa on käsitelty yleisellä tasolla kalorimetrian ja reaktiokalorimetrian teoriaa, termodynamiikkaa sekä sinkkirikasteen liuotuksen kemiaa. Lisäksi työssä esitellään erilaisten kalorimetrien ja termoanalyyttisten mittauslaitteiden toimintaperiaatteita. Työn kokeellisessa osassa selvitettiin reaktiokalorimetrin mittaustulosten tarkkuutta vesi- kokeiden avulla. Laitteistolla määritettiin myös reaktiolämmöt sinkkisulfidin liukenemisreaktiolle sekä elohopeasuolan saostusreaktiolle. Lisäksi tutkittiin sekoitusnopeuden, lämpötilan ja kiintoainepitoisuuden vaikutusta mittaustuloksiin. Reaktiokalorimetrillä suoritettujen kokeiden perusteella havaittiin, että reaktiolämpöjen absoluuttisten arvojen määrittäminen laitteistolla on käytännössä vaikeaa. Koska reaktiokalorimetrillä pystytään määrittämään vain mittauksen aikana tapahtunut kokonaislämpömuutos, vaikuttavat mahdolliset faasimuutokset ja reaktorin lämpöhäviöt mittaustuloksiin. Näiden tekijöiden vaikutus on pyrittävä eliminoimaan tai niiden vaikutus on tunnettava tarkkaan, jos laitteella halutaan saada luotettavia reaktiolämpömittaustuloksia. Laitteiston mittaustarkkuus huononee huomattavasti, kun reaktorin lämpötila nousee yli 60 °C:een. Laitteistolla mitatut reaktiolämmöt poikkeavat huomattavasti vastaavista kirjallisuuden arvoista. Vedelle määritetyt ominaislämpökapasiteetit poikkeavat kirjallisuuden arvoista enintään 5 alle 90 °C:een lämpötilassa.

Benthos of Spanish lakes and reservoirs

A summary of the results from the study of benthos of lakes and reservoirs in Spain is provided, with a list of the species found to date. Spanish natural lakes are smaller than European lakes; the largest is Lake Sanabria, of glacial origin, which is 3 Km long and half a kilorneter wide. Many are very small and situated in the mountains; more than 200 hundred have been recorded in Spain, but only in Lake Sanabria and Lake Banyoles have the benthos been studied. Lake Sanabria is a cold oligotrophic, monomictic lake with oxygen always present in the deepest zones. Its fauna is similar to that of other central European lakes, with Mici.opsectra c.orztractu (a chironomid) as the dominan1 species. Lake Banyoles is a karstic, monomictic and multibasin lake; despite the low primary productivity, due to the abundante of sulphate in the water, the allochthonous inflow of organic matter and the inflow of water from bottom springs, the profunda1 environinent is very stressing for benthic fauna. Very low oxygen concentrations and high sulphide content in the water and sediments dueto meromixis mean that only the larva of the dipteran Chaohoi.lcs flai7icans was present in one of the 5 basins of the lake. In other basins, when oxygen is available (no meromixis), the fauna is similar to that of tlie inineralized lakes of the Aegean region and some lakes in central Italia. On the other hand, preliminary data from the Pyrenean lakes and from Sierra Nevada ponds reveal no differences with northern cold lakes. Tlie largest lakes in Spain are the reservoirs. There are nearly 1000 and data are available on 100 of them, including the kargest. In addition to oxygen and sulphide content in the bottom waters, water level fluctuation and high sedimentation rates are disturbance factors that prevented the organization of the community. Allochthonous inputs of organic matter are also an important factor both in the reservoirs and also in the small, oligotrophic lakes like Banyoles and Sanabria. As a result the meiofaunal loop is very important in many of the Spanish water bodies . For this reason the natural lakes and reservoirs of Spain are dominated by Oligochaeta, small crustaceans and the microcarnivore chironomids (such as Procladi~ls, Cladopelma and Mi(,rnc.hil-onnmus) that feed on these meoifaunal elements. The phytophagous chironomids, like Chironomus, are only abundan1 in the shallow areas of mesotrophic and eutrophic reservoirs. This situation makes it difficult to apply the typological system of SAETHER which predicts with some confidence only the benthic communities of Spanish natural lakes above 1500 m in the Pyrenees or the ponds above 2000 m in Sierra Nevada mountains. Higher temperatures (which originate a longer stratification period), the presence of sulphate in the waters of the eastern part of Spain and high inputs of sediments and allochthonous organic matter seem to be the factors that originated the differences between the benthic profunda1 faunas of Spanish lakes and reservoirs and those of the temperate lakes of north and central Europe.

Sinkkirikasteen suoraliuotusreaktorin kehittäminen

Hydrometallurgiseen sinkinvalmistusprosessiin kuuluu yleensä pasutus, liuotus, puhdistus ja elektrolyysi. Sinkkirikasteen suoraliuotusmenetelmässä sinkkisulfidi liuotetaan suoraan ilman pasutusta. Suoraliuotusprosessissa prosessiliuokseen lietettyä sinkkisulfidia syötetään liuotusreaktoriin, jossa on liuottimena rikkihappoa. Sinkkisulfidi reagoi ferrisulfaatin kanssa muodostaen sinkkisulfaattia ja ferrosulfaattia, ja samalla rikki hapettuu alkuainerikiksi. Ferro-ionit hapetetaan takaisin ferri-muotoon syöttämällä reaktoriin happea. Tämän työn tarkoituksena oli löytää uudentyyppinen, edullisempi reaktori sinkkirikasteen suoraliuotukseen. Suunnittelussa pyrittiin kehittämään mahdollisimman monipuolinen koereaktori, jota voidaan hyväksikäyttää useiden suoraliuotuksen ilmiöiden, esimerkiksi hapen liukenemisen, tutkimiseen. Reaktori mitoitettiin pilot-laitteiston kokoiseksi. Valmiilla koelaitteistolla tehtiin lyhyt sarja kokeita ja jo niiden perusteella pystyi havaitsemaan reaktorin toimivan hyvin. Kokeiden päätarkoituksena oli testata laitteiston toimivuutta ja soveltuvuutta sinkkirikasteen liuotukseen. Työhön kuului myös kehitetyllä reaktorilla myöhemmin suoritettavan koetoiminnan suunnittelu.