Electrocoagulation in the treatment of industrial waters and wastewaters

Chemical coagulation is commonly used in raw water and wastewater treatment plants for the destabilisation of pollutants so that they can be removed in the subsequent separation processes. The most commonly used coagulation chemicals are aluminium and iron metal salts. Electrocoagulation technology has also been proposed for the treatment of raw waters and wastewaters. With this technology, metal cations are produced on the electrodes via electrolysis and these cations form various hydroxides in the water depending on the water pH. In addition to this main reaction, several side reactions, such as hydrogen bubble formation and the reduction of metals on cathodes, also take place in the cell. In this research, the applications of electrocoagulation were investigated in raw water treatment and wastewater applications. The surface water used in this research contained high concentrations of natural organic matter (NOM). The effect of the main parameters – current density, initial pH, electric charge per volume, temperature and electrolysis cell construction – on NOM removal were investigated. In the wastewater treatment studies, the removal of malodorous sulphides and toxic compounds from the wastewaters and debarking effluents were studied. Also, the main parameters of the treatment, such as initial pH and current density, were investigated. Aluminium electrodes were selected for the raw water treatment, whereas wastewaters and debarking effluent were treated with iron electrodes. According to results of this study, aluminium is more suitable electrode material for electrocoagulation applications because it produces Al(III) species. Metal ions and hydroxides produced by iron electrodes are less effective in the destabilisation of pollutants because iron electrodes produce more soluble and less charged Fe(II) species. However, Fe(II) can be effective in some special applications, such as sulphide removal. The resulting metal concentration is the main parameter affecting destabilisation of pollutants. Current density, treatment time, temperature and electrolysis cell construction affect the dissolution of electrodes and hence also the removal of pollutants. However, it seems that these parameters have minimal significance in the destabilization of the pollutants besides this effect (in the studied range of parameters). Initial pH and final pH have an effect on the dissolution of electrodes, but they also define what aluminium or iron species are formed in the solution and have an effect on the ζ-potential of all charged species in the solution. According to the results of this study, destabilisation mechanisms of pollutants by electrocoagulation and chemical coagulation are similar. Optimum DOC removal and low residual aluminium can be obtained simultaneously with electrocoagulation, which may be a significant benefit of electrocoagulation in surface water treatment compared to chemical coagulation. Surface water treatment with electrocoagulation can produce high quality water, which could be used as potable water or fresh water for industrial applications. In wastewater treatment applications, electrocoagulation can be used to precipitate malodorous sulphides to prevent their release into air. Technology seems to be able to remove some toxic pollutants from wastewater and could be used as pretreatment prior to treatment at a biological wastewater treatment plant. However, a thorough economic and ecological comparison of chemical coagulation and electrocoagulation is recommended, because these methods seem to be similar in pollutant destabilisation mechanisms, metal consumption and removal efficiency in most applications.

Ultrafiltration of pulp mill bleaching effluents

Main objective of this research was to find suitable polymeric ultrafiltration membranes with high retentions, good capacities and low fouling tendencies for the E2- and EP-effluent ultrafiltration. Purpose was to treat alkaline bleaching effluents with ultrafiltration in a way that permeates of the filtrations could be recycled back to process and the consumption of fresh water in the pulp mill could be reduced significantly. In the theoretical part of this work the challenges set by the pulp and paper indus-try processes for membranes were examined. An overview of the membrane tech-nology in the pulp industry was also provided. In addition process conditions in the chemical pulp bleaching and properties of bleaching effluents were discussed in literature study. In experimental part the E2- and EP-stage bleaching effluents from Stora Enso Imatra kraft pulp mill were ultrafiltered with CR250- and CR200-filters. Suitable membranes for ultrafiltration were chosen after screening experiments. Concentra-tion experiment was made for the E2-effluent in order to estimate water saving potential. The E2-effluent was finally ultrafiltered in the pulp mill in order to test the feasibility of ultrafiltration in a real industrial environment. Good membrane for the EP-effluent ultrafiltration based on the EP-screening ex-periments was polyethersulfone membrane UP020 with cut-off value of 20 000 Da. Polysulfone membrane UFX05 with cut-off value of 5 000 Da was promising membrane for the ultrafiltration of the E2-effluent. Based on the concentration filtration of the E2-effluent with UFX05 membrane the water saving potential could be 2.2 m3/Adt for the industrial scale ultrafiltration process. Retention re-sults, such as average COD retention of 60 %, from the trial filtration at the pulp mill with UFX05 membrane were modest compared to the screening experiments, where average COD retention was 75 %. Therefore tighter ultrafiltration mem-branes should be tested for the ultrafiltration of the E2-effluent. The UP020 mem-brane seemed to be suitable for the ultrafiltration of the EP-effluent however con-centration and pilot scale ultrafiltration experiments are needed to verify this.

Main diseases of pejerrey (Odontesthes bonariensis) in central Argentina

Argentina's central region includes an important area covered by shallow pampean lakes and dams. In these environments, fishing of pejerrey Odontesthes bonariensis Valenciennes, 1835 (Pisces, Atherinopsidae), the most important fresh-water fish of the country, is a relevant social activity and also a considerable economic resource. The main diseases found in this species were studied from 1992 to 2003 in the provinces of Córdoba, La Rioja and Santa Fe (30º and 35º S, 61º and 67º W). Most cases were registered in high temperature months. Lernaea sp and Aeromonas hydrophila were the etiological agents most frequently found. The trophic characteristics of the aquatic environments enhanced disease processes and caused massive death of O. bonariensis, due to complex hydrochemical interactions.

Arseeni ja elohopea maaperässä ja vesistöissä

Maapallon väestön kasvaessa ja tarpeen makealle vedelle, ruualle ja viljelymaalle noustessa on tärkeää alkaa kiinnittää entistä tarkemmin huomiota vesistöjen ja maaperän saastumiseen myrkyllisillä raskasmetalleilla. Erityisesti elohopea ja arseeni, jotka jo nyt vaikuttavat heikentävästi miljoonien ihmisten elämään eri puolilla maapalloa, on syytä ottaa huolelliseen tarkkailuun. Raskasmetallien päästölähteet voidaan jakaa kahteen luokkaan, luonnollisiin ja ihmisperäisiin. Ihmisperäisiin päästölähteisiin voidaan vaikuttaa muun muassa teollisuutta ja liikennettä koskevalla lainsäädännöllä. Luonnollisiin päästölähteisiin vaikuttaminen on huomattavasti haastavampaa, mutta niiden haittaa ihmisille on mahdollista pienentää muun muassa parempien vedenpuhdistustekniikoiden avulla. Tämän työn kirjallisuusosassa tullaan esittelemään erityyppisiä luonnossa esiintyviä arseenin ja elohopean yhdisteitä, suurimpia arseenin ja elohopean päästölähteitä, sekä näiden raskasmetallien haitallisia terveysvaikutuksia. Kokeellisessa osassa tullaan keskittymään arseenin analysointiin nestemäisistä näytteistä. Näytteinä käytettiin tuntemattomilta kaatopaikoilta otettuja suotovesinäytteitä, sekä Pien-Saimaan pintavesinäytteitä. Analyyseihin on käytetty ICP-AES laitteistoa sekä kapillaarielektroforeesia.

Veden desinfiointi UV-LED-valolla

Veden riittämätön puhdistus aiheuttaa riskin veden käyttäjille. Miljoonia kuolemia vuosittain aiheuttavien vesiteitse leviävien sairauksien ehkäisemiseksi vaaditaan tehokkaita juomaveden desinfiointimenetelmiä. Kuivuuden ja väestönkasvun myötä veden tarve on lisääntynyt ja vedenkulutus tulee yhä kasvamaan. Tästä syystä mahdollisuus kierrättää vettä hyödyntäen sitä esimerkiksi kasteluun on saanut yhä enemmän huomiota. Kierrätettävä vesi on kuitenkin käsiteltävä huolellisesti sen sisältämän mikrobiologisen kontaminaatioriskin vuoksi. Ultraviolettisäteily luokitellaan fysikaaliseksi desinfiointimenetelmäksi. Sen tehokkuus perustuu mikro-organismien absorboimaan UV-säteilyyn, jonka aiheuttamien DNA:ssa tai RNA:ssa tapahtuvien muutoksien seurauksena mikro-organismi inaktivoituu ja estyy lisääntymästä. UV-desinfioinnissa on tyypillisesti käytetty elohopeahöyrylamppuja. Vaihtoehtoinen UV-säteilyn lähde ovat LEDit eli valoa emittoivat diodit. Matalapaine-elohopeahöyrylamppujen emittoima säteily on aallonpituudella 254 nm ja keskipaine-elohopeahöyrylamppujen emittoima säteily on laajakaistaista säteilyä. Energiatehokkuuden lisäksi LEDien etuna on, että niillä voidaan tuottaa kapeakaista säteilyä aallonpituudella, joka parhaiten absorboituu DNA:han. Tämän diplomityön tarkoituksena oli tutkia, onko UVC-alueen aallonpituuksien yhdistelmillä synergistisiä etuja LEDien desinfiointitehokkuuteen, kun desinfioidaan virtaavaa vettä useilla säteilyannoksilla ja indikaattorimikrobina käytetään kolibakteeria. Tavoitteena oli myös tutkia tällä hetkellä saatavissa olevien LEDien desinfiointitehokkuutta energiatehokkuuden näkökulmasta. Yksittäisistä aallonpituuksista desinfiointitehokkuudeltaan parhaimmaksi osoittautui 260 nm, aallonpituuksien yhdistelmistä tehokkain oli 265 nm:n ja 260 nm:n yhdistelmä. Muilla aallonpituuksien yhdistelmillä ei saavutettu odotettua parempaa desinfiointitehokkuutta. Optiselta teholtaan parhaimmat LEDit, 265 nm, 270 nm ja 275 nm olivat kokeiden perusteella myös energiatehokkuuden kannalta tarkasteltuina parhaimmat sekä yksittäin että yhdistelminä. UVC-aallonpituuksia emittoivien LEDien optisen tehokkuuden paraneminen on edellytys LEDien hyödyntämiselle desinfioinnissa.

Cyanobacterial toxins in Portugal: effects on aquatic animals and risk for human health

Toxic cyanobacteria are common in Portuguese freshwaters and the most common toxins are microcystins. The occurrence of microcystin-LR (MCYST-LR) has been reported since 1990 and a significant number of water reservoirs that are used for drinking water attain high levels of this toxin. Aquatic animals that live in eutrophic freshwater ecosystems may be killed by microcystins but in many cases the toxicity is sublethal and so the animals can survive long enough to accumulate the toxins and transfer them along the food chain. Among these, edible mollusks, fish and crayfish are especially important because they are harvested and sold for human consumption. Mussels that live in estuarine waters and rivers where toxic blooms occur may accumulate toxins without many significant acute toxic effects. In this study data are presented in order to understand the dynamics of the accumulation and depuration of MCYST-LR in mussels. The toxin is readily accumulated and persists in the shellfish for several days after contact. In the crayfish the toxin is accumulated mainly in the gut but is also cleared very slowly. In carps, although the levels of the toxins found in naturally caught specimens were not very high, some toxin was found in the muscle and not only in the viscera. This raises the problem of the toxin accumulation by fish and possible transfer through the food chain. The data gathered from these experiments and from naturally caught specimens are analyzed in terms of risk for human consumption. The occurrence of microcystins in tap water and the incidence of toxic cyanobacteria in fresh water beaches in Portugal are reported. The Portuguese National Monitoring Program of cyanobacteria is mentioned and its implications are discussed.

Kartonkikoneen tuoreveden käytön vähentäminen kemiallisesti puhdistettua jätevesikirkastetta hyödyntäen

Tämän diplomityön tarkoituksena oli tutkia mahdollisuutta hyödyntää kemiallisesti puh-distettua jätevettä prosessivetenä. Vedensäästöpotentiaalin perusteella tutkimuskohteeksi valittiin kartonkikone 4. Tutkimuksen tavoite oli tuoreveden käytön ja jätevesipäästöjen vähentäminen Stora Enso Imatran tehtailla. Työn kirjallisuusosa keskittyy kemialliseen jätevedenkäsittelyyn, kartonkikoneen veden käyttöön ja prosessiveden laatuun vaikuttaviin tekijöihin. Työn kokeellisessa osassa laa-dittiin vesitase tuoreveden käyttökohteiden ja veden tarpeen määrittämiseksi. Kemialli-sesti puhdistetun jäteveden ja prosessiveden ominaisuudet määritettiin, jotta saatiin sel-ville ne ominaisuudet, jotka voisivat estää jätevesikirkasteen hyötykäytön. Laboratoriomääritykset osoittivat, että hyötykäytön esteenä ovat jätevesikirkasteen kiin-toaine-, sulfaatti- ja karbonaattipitoisuus sekä mikrobitaso ja väri. Metallien ja suolaionien haittavaikutusten selvittäminen vaatii lisätutkimusta. Lisäpuhdistusmenetelmien avulla, kuten käänteisosmoosi, jätevesikirkasteen laatu saataisiin vastaamaan prosessiveden tasoa ja hyötykäyttö olisi mahdollista myös kartonkikone 4:n ulkopuolella.

Effects of reflection and social isolation on crayfish behaviour /

Visual stimuli and socialization influence exploratory behaviour in crayfish. The predominant components of spontaneous exploratory behaviour were determined by observing the activity of solitary adult crayfish (Procambarus clarkii) in a glass aquarium containing fresh water and no objects. Five distinct behaviours were observed: rearing up (climbing on the wall), turning around, cornering (facing the comer), backward walking, and crossing (crossing the midline of the aquarium). The frequency of rearing up, cornering and turning around decreased when reflection from the glass wall was blocked with black cardboard, black paint or non-reflective transparent plastic. In a tank containing mirrors on one side and non-reflective plastic on the other, crayfish cornered, reared up, and turned around more in front of the mirrors. Socialization was necessary for crayfish to respond to the reflection. Crayfish that were housed in pairs for two weeks exhibited more rearing up, turning around and cornering in front of the mirrors than in the non-reflective side. Crayfish isolated for two weeks did not show these differences. Socialized crayfish also exhibited more rearing up, turning around and cornering than did isolated crayfish. Thus, crayfish respond to visual stimuli provided by a glass tank, but the responds depends on socialization.

Microstructural and geochemical investigation of North American lower-middle Paleozoic trilobites and recent arthropods

Trilobites ¥tere collected from Ordovician and Devonian formations of Ontario} New York} Ohio} Oklahoma} and Indiana. Diversity was generally low} but 19..?telllS and Ph..~tY>ps ¥tere the most abundant species from the Ordovician and Devonian} respectively. Recent marine arthropods ¥tere collected from the Atlantic shore of the middle Florida Keys} and from the Pacific and lagoonal waters at Cape Beale} B. C. Fresh-water arthropods were collected along the shore of the Severn River in northcentral Ontario. Cuticles ¥tere analyzed for major} minor and trace elements, 180 and 13C isotopes, as ¥tell as examined by scanning electron micr?scope to identify original and diagenetic fabrics. Examination of trilobite cuticles by scanning electron microscope revealed several microstructures consistent with those observed in Recent arthropods. Microstructures} such as setae and tegumental gland duct openings} in like sized Lim/IllS and Isoteline trilobites may indicate common ancestral origins for these organisms, or simply parallel cuticle evolutions. The dendritic microstructure, originally' thought to be a diagenetic indicator, was found in Recent specimens and therefore its presence in trilobites may be suggestive of the delicate nature of diagenesis in trilobites. The absence of other primary microstructures in trilobites may indicate alteration, taxonomic control} or that there is some inherent feature of S EM examination which may' not allow detection of some features} while others are apparently visit·le onl~1 under SH.·1. The region of the cuticle sampled for examination is also a major influence in detecting pristine microstructures, as not all areas of trilobite and Recent arthropod cuticles will have microstructures identifiable in a SEM study. Subtleties in the process of alteration, however} ma~·· leave pristine microstructures in cuticles that are partial~/ silicified or do 10m itized, and degree and type of alteration may vary stratigraphically and longitudinally within a unit. The presence of fused matrices, angular calcite rhombs, and pyrite in the cuticle are thought to be indicative of altered cuticles, although pyritization may not affect the entire cuticle. t-~atural processes in Recent arthropods, such as molting, lead to variations in cuticle chemistries, and are thought to reflect the area of concentration of the elements during calcification. The level of sodium in Recent arthropods was found to be higher than that in trilobites, but highly mobile when sUbjected to the actions of VY'€'athering. Less saline water produced lovy'€'r magnesium and higher calcium values in Recent specimens .. and metal variations in pristine Ordovician trilobite cuticle appears to follow the constraints outlined for Recent arthropods, of regulation due to the chemislry of the surrounding medium. In diagenetic analysis, sodium, strontium and magnesium proved most beneficial in separating altered from least altered trilobites. Using this criterion, specimens from shale show the least amount of geochemical alteration, and have an original mineralogy of 1.7 - 2.4 mole % MgC03 (8000 t(> 9500 ppm magnesium) for both /s>..?/e/11S lJA'i.riff!11S and PseIAit'11J17ites I..itmirpin..itl/~ and 2.8 - 3.3 mole % MgC03 (5000 to 7000 ppm magnesium) for Ph.i{).?PS This is Slightly lower than the mineralogy of Recent marine arthropods (4.43 - 12.1 mole % MgC03), and slightly higher than that of fresh-water crayfish (0.96 - 1.82 mole % MgC03). Geochemically pristine trilobites were also found to possess primary microstructures. Stable isotope values and trends support the assertion that marine-meteoriclburial fluids were responsible for the alteration observed in a number of the trilobite specimens. The results of this stUdy suggest that fossil material has to be evaluated separately along taxonomic and lithological lines to arrive at sensible diagenetic and e nvironmenta I interpretations.

Faut-il en finir avec le développement durable ? Regard sur les zones humides méditerranéennes.

A partir de projets de conservation de la biodiversité ou de gestion intégrée des zones humides méditerranéennes, cet article montre que le développement durable de ces milieux relève avant tout d’une réflexion politique sur le maldéveloppement. Les projets de conservation de la biodiversité tentent de concilier conservation et développement avec divers succès. Parmi les obstacles, la réduction de la ressource en eau douce s’ajoute aux inégalités sociales et à la pauvreté. Favoriser et gérer les changements institutionnels, accroître le capital social des parties prenantes, apprendre et décider collectivement, constituent les éléments clés du développement durable.Il existe encore de nombreuses disparités dans les processus démocratiques aux échelles locales,régionales et nationales,mais un développement participatif est proposé. En étant davantage centré sur les besoins des populations locales que sur la croissance économique,en étant plus réflexif,en plaçant la critique de la science et la co-construction de projets au coeur du processus, le développement participatif des zones humides méditerranéennes peut offrir une alternative aux approches qui ont prévalues jusqu’à présent. Le développement durable des zones humides méditerranéennes est encore possible s’il accroît la capacité d’adaptation des systèmes sociaux et écologiques afin de repousser toute irréversibilité.

Développement d’outils analytiques pour évaluer la biodisponibilité du Cd dans les eaux douces

Les phytochélatines (PC) sont des polypeptides ayant la structure générale, (alpha-Glu-Cys)n-Gly, où n = 2 à 11. Leur synthèse est induite par un grand nombre de végétaux en réponse à une élévation de la concentration du milieu en métaux, en particulier le cadmium (ci-après, Cd). Le but de cette étude a été de développer un outil pour évaluer la biodisponibilité du Cd dans les eaux douces. Pour ce faire, une méthode analytique a été réalisée afin de déterminer les phytochélatines induites dans les algues C. reinhardtii. Celle-ci consiste à utiliser la chromatographie liquide couplée à la spectrométrie de masse en tandem (LCHP-SM/SM) "on-line". L’ionisation des molécules est celle faite par électronébulisation (IEN) (traduction de electrospray ionisation). L’objectif principal de ce mémoire est la validation de cette méthode : la détermination des courbes de calibration et des limites de détection et l'identification d'interférences potentielles. L’utilisation de dithiothreitol (DTT) à une concentration de 25 mM a été nécessaire à la conservation de la forme réduite des phytochélatines. En effet, suite à la validation de la méthode d’analyse des phytochélatines il a été démontré qu’elle représente un potentiel d’application. Ceci dans la mesure où l’induction des phytochélatines (PC2, PC3 et PC4) dans les algues C. reinhardtii a été possible à deux concentrations de Cd (1 x 10-7 M et 1 x 10 6 M) et ce, après plusieurs temps d'induction (1, 2, 4, et 6 h). Ainsi, l’étude de la stabilité des phytochélatines a été réalisée et toutes les températures examinées ont démontré une diminution des phytochélatines analysées par HPLC-ESI-MS/MS. Il se pourrait que la cause de la dégradation des phytochélatines soit physique ou chimique plutôt que bactérienne. Toutefois, un approfondissement au niveau de la purification de la solution d’extraction serait nécessaire à la mise au point de la dite méthode analytique afin de quantifier les phytochélatines dans l’algue C. reinhardtii.

La préservation de l'eau face à la pollution industrielle : le rôle de l'État Québécois

Le Québec, qui dispose de près de 3 % des ressources d’eau douce de la planète, a longtemps géré cette ressource selon une rationalité permissive, ce qui a encouragé la pollution de celle-ci. Le secteur industriel est à l’origine des rejets de polluants les plus difficiles à décomposer, lesquels auraient déjà occasionné une baisse de la biodiversité. Dès 1978, le Québec commence à réaffirmer le rôle de l’État dans la protection et la préservation de l’eau. À ce sujet, un programme d’assainissement des eaux, associé à une législation plus contraignante, a permis de récupérer les eaux des fleuves et des rivières les plus polluées. Avec l’adoption de la Politique nationale de l’eau et de la Loi affirmant le caractère collectif des ressources en eau et visant à renforcer leur protection, le Québec réaffirme de nouveau le rôle de l’État en tant que fiduciaire des ressources en eau dans le but de les préserver et de les gérer pour les générations futures.

L’or bleu, une ressource à redéfinir : la conciliation du droit à l’eau et de ses enjeux

Naguère perçue comme une ressource inépuisable, nous assistons actuellement à une crise mondiale de l’eau douce. Dans ce contexte, il est primordial de vérifier si et comment les individus peuvent bénéficier d’une protection adéquate en ce qui a trait à la fourniture d’eau et comment une telle protection pourrait être mise en place. Au moyen d’une approche juridicopolitique, le présent mémoire vise à renforcer l’existence d’un droit de l’homme à l’eau et à analyser la problématique de la gestion des ressources en eau à travers différents accords commerciaux et la gouvernance de l’eau, à l’échelle internationale et au Canada. Au final, le mémoire démontre qu’il pourrait exister une telle protection puisqu’un droit à l’eau évolue en droit international, mais le caractère exécutoire de ce droit est conditionnel à sa reconnaissance par les États. L’observation de ce cas a plutôt mis en lumière une tendance à la privatisation des ressources en eau à l’échelle internationale, tendance qui devrait être révisée afin que le droit à l’eau puisse être réalisé pour tous.

Petrography, Geochemistry and Diagenesis of Coral Deposits of Kavaratti and Minicoy Islands, Lakshadweep, India

In the present thesis the petrographic, geochemical and digenetic variability of the sediments in the islands of Kavaratti and Minicoy has been investigated .The beach profile studies show that in the Kavaratti lagoon beach, the slope is steeper in the southern and south central part than in the northern end’s marginal deposition is taking place in the northern end of the Kavaratti island, whereas a marginal erosion is observed at the southern end. In Minicoy the slope of the lagoon beach is gentle in the south and is slightly steeper at the northern part of the beach. The southern and northern beach sections show a marginal deposition. Based on the mineralogical and geochemical studies it is concluded that the main digenetic changes observed is the transformation of aragonite to LMC.The transformation takes place mainly in the vadose zone and is caused by the abundance of fresh water infiltration.

Sediment Budgeting Studies for the Kollam Coast

The Sediment budgeting studies are done to bring out the coastal processes at work, to understand the beach-innershelf sedimentary dynamics and to assess the stability of any coastal stretch. There is a dearth of such studies as far as the Indian coast is concerned. The Chavara coast of Kollam district, Kerala, is world famous for its rich heavy mineral resources. These mineral resources are being commercially mined by the Indian Rare Earths Ltd. (IREL) and Kerala Minerals and Metals Ltd. (KMML), two Public Sector Undertakings located in the area. The impact of mining on stability of the beach has been a point of debate among the local people as well as researchers. The coastal stretch of 22km length from Neendakara to Kayamkulam which is referred to as the Chavara coast. The tidal, wind driven and continental shelf currents, there could also be the contribution of coastal trapped waves and baroclinic flow associated with the plumes of fresh water coming from the estuaries. The main objectives of the study are the hydrodynamic processes and mechanism involved in the sediment movement along the Chavara coast, Identify the different sources and sinks of beach sand along the coast, Quantify the sediment input/output into/from the coast and assess the erosion/accretion scenario of the coast.