No description available.

The need of making arsenic contaminated ground water potable is urgent in parts of Burkina Faso. An implementation of a treatment design using Granular Ferric Hydroxide (GFH) is under development. Water from a tube-well in Lilgomdé, Yatenga province, Burkina Faso, has been treated with the adsorbent GFH through column experiments. The water had an arsenic concentration varying between 99 and 215 μg/L and an average pH of 7.9. The study has shown that arsenic, predominantly in the form of arsenate, can be adsorbed to the material in significant amounts despite a high natural pH and the presence of ions competing with arsenic for adsorption sites on the GFH. When run through the column, the pH of the effluent water drastically decreased in the beginning. However, the low pH was soon followed by a slower readjustment towards the pH of the influent water. The adsorption of phosphates and fluorides was also studied. Both competitors exist in higher molar quantities than arsenic in the ground water. Even though arsenic displays a higher affinity for the GFH, an average 44 % of total phosphate and 64 % of the fluoride were adsorbed, making them a factor affecting the results of the study. Hydrogen carbonate is also believed to affect the adsorption process but this could not be confirmed. The empty bed contact time (EBCT), describing the average time of contact between the adsorbent and the water, has shown to be of importance. Increasing the EBCT resulted in notably more arsenic being adsorbed per volume GFH. When increasing the contact time, the study showed that reducing the speed of the flow was more effective than increasing the volume of the adsorbent. The GFH was also found to have a self-regenerating ability to a certain extent. When interrupting the experiment and leaving the column material in the aqueous solution for several days, the arsenic adsorption capacity after the break was shown to be higher than just before it. A 13 % increased capacity was shown in one experiment. Conclusively, the results of this study suggest no hindrances towards developing larger scale columns and prototypes to be applied at tube-well pump stations. Further investigations on the treatment method with GFH, on arsenic contaminated water, are recommended.

No description available.

<p>Mine waste from Ljusnarsbergsfältet in Kopparberg, Sweden, is considered to constitute a great risk for human health and the surrounding environment. Some of the waste rock consists of sulphide minerals. When sulphide minerals come into contact with dissolved oxygen and precipitation, oxidation may occur resulting in acid mine drainage (AMD) and the release of heavy metals. The purpose of this study has been to characterise the waste material and try to chemically stabilize the waste rock with a mixture of sewage sludge and calcium carbonate. The drawback of using organic matter is the risk that dissolved organic matter can act as a complexing agent for heavy metals and in this way increase their mobility. An additional study to examine this risk has therefore also been performed.</p><p>The project started with a pilot study in order to identify the material fraction that was suitable for the experiment. When suitable material had been chosen, a column test was carried out for the purpose of studying the slurry’s influence on the mobility of metals along with the production of acidity. To clarify the organic material’s potential for complexation a pH-stat batch test was used. Drainage water samples, from the columns, were regularly taken during the experiment. These samples were analysed for pH, electrical conductivity, alkalinity, redox potential, dissolved organic carbon (DOC), sulphate and leaching metals. The effluent from the pH-stat-test were only analysed on a few occasions and only for metal content and change in DOC concentration.</p><p>The results from the laboratory experiments showed that the waste rock from Ljusnarsberg easily leached large amounts of metals. The stabilization of the waste rock succeeded in maintaining a near neutral pH in the rock waste leachate, compared to a pH 3 leachate from untreated rock waste The average concentration of copper and zinc in the leachate from untreated waste rock exceeded 100 and 1000 mg/l respectively, while these metals were detected at concentrations around 0.1 and 1 mg/l, respectively, in the leachate from the treated wastes. Examined metals had concentrations between 40 to 4000 times lower in the leachate from treated waste rock, which implies that the stabilisation with reactive amendments succeeded. The long term effects are, however, not determined. The added sludge contributed to immobilise metals at neutral pH despite a small increase in DOC concentration. The problem with adding sludge is that if pH decreases with time there is a risk of increased metal leaching.</p> / <p>Gruvavfallet från Ljusnarsbergsfältet i Kopparberg anses utgöra en stor risk för människors hälsa och den omgivande miljön. En del av varpmaterialet, ofyndigt berg som blir över vid malmbrytning, utgörs av sulfidhaltigt mineral. Då varpen exponeras för luft och nederbörd sker en oxidation av sulfiderna, vilket kan ge upphov till surt lakvatten och läckage av tungmetaller. Syftet med arbetet har varit att karaktärisera varpen och försöka stabilisera den med en blandning bestående av mesakalk och avloppsslam, samt att undersöka risken med det lösta organiska materialets förmåga att komplexbinda metaller och på så vis öka deras rörlighet.</p><p>Efter insamling av varpmaterial utfördes först en förstudie för att avgöra vilken fraktion av varpen som var lämplig för försöket. När lämpligt material valts ut utfördes kolonntest för att studera slam/kalk-blandningens inverkan på lakning av metaller, samt pH-statiskt skaktest för att bedöma komplexbildningspotentialen hos det organiska materialet vid olika pH värden. Från kolonnerna togs lakvattenprover kontinuerligt ut under försökets gång för analys med avseende på pH, konduktivitet, alkalinitet, redoxpotential, löst organiskt kol (DOC), sulfat och utlakade metaller. Lakvattnet från pH-stat-testet provtogs vid ett fåtal tillfällen och analyserades endast med avseende på metallhalter och förändring i DOC-halt.</p><p>Resultatet från den laborativa studien visade att varpmaterialet från Ljusnarsberg lätt lakades på stora mängder metaller. Den reaktiva tillsatsen lyckades uppbringa ett neutralt pH i lakvattnet från avfallet, vilket kan jämföras med lakvattnet från den obehandlade kolonnen som låg på ett pH kring 3. Medelhalten av koppar och zink översteg under försöksperioden 100 respektive 1000 mg/l i lakvattnet från det obehandlade avfallet, medan halterna i det behandlade materialets lakvatten låg kring 0,1 respektive 1 mg/l. Av de studerade metallerna låg halterna 40-4000 gånger lägre i lakvattnet från den behandlade kolonnen, vilket innebär att slam/kalk-blandningen har haft verkan. Stabiliseringens långtidseffekt är dock okänd. Det tillsatta slammet resulterade inte i någon större ökning av DOC-halten i det pH-intervall som åstadkoms med mesakalken. Utifrån pH-stat-försöket kunde det konstateras att det tillsatta slammet bidrog till metallernas immobilisering vid neutralt pH, trots en liten ökning av DOC-halten. Om en sänkning av pH skulle ske med tidens gång föreligger dock risk för ökat metalläckage.</p>

Kate Valley is a municipal waste landfill situated in Waipara, Northern Canterbury. It is a joint venture between the 6 local regional councils and Transwaste Canterbury Ltd to help dispose of waste quantities generated in the wider Canterbury region. Landfill waste disposal also generates waste streams. Major waste streams can include methane gas production and liquid leachate. One practice which can turn liquid leachate waste streams into a nutrient source for plants is land irrigation. It is important to have a thorough understanding of the interactions involved with leachate, soil structure, soil microbiology, flora. This thesis investigates the sorption mechanisms between Kate Valley soil and leachates, through batch and column experiments. Sorption mechanisms between leachate and soil were investigated through batch and column tests. Ex-situ soil samples were extracted from Kate Valley, along with raw leachate samples for batch tests at a soil to liquid ratio of 30 g vs. 70 ml respectively. Tested dilution leachate strengths ranged from raw to 50x raw leachate dilution; meanwhile soil samples were categorized into 3 groups based on soil depth: 0-20 cm, 20-40 cm, and 40-60 cm. Column tests were conducted on 3 extracted in-situ soil column monoliths. Column test irrigation conditions included: control case, 2x and 10x raw leachate dilution, and 200 mg/L KBr (bromide column), where the same soil column was used for bromine testing after control testing had ceased. Batch results suggest deeper soils are less effective at sorption of ammonia, where partitioning coefficient ranged from 9.5x*10-7 to 6.4*10-7 L/mg for 0-20 cm soil to 40-60 cm soil respectively. Column results generally showed lower partitioning capacity than batch results, at 4*10-8 and 5*10-8 L/mg for 10x and 2x dilution leachate irrigation respectively. Discrepancies in experimental data have been attributed to: different dilution leachates tested between batch and column tests, making it difficult for direct comparison; extreme soil to liquid ratios employed in experiments; direct data comparison between the “full-contact” experimental data (between leachate and soil), obtained from batch tests with column results, where not all soil may have been fully exposed for shrinkage of boundary layers of soil particles; and oxygen exposure of samples during testing and sampling, possibly encouraging nitrification.

Mine waste from Ljusnarsbergsfältet in Kopparberg, Sweden, is considered to constitute a great risk for human health and the surrounding environment. Some of the waste rock consists of sulphide minerals. When sulphide minerals come into contact with dissolved oxygen and precipitation, oxidation may occur resulting in acid mine drainage (AMD) and the release of heavy metals. The purpose of this study has been to characterise the waste material and try to chemically stabilize the waste rock with a mixture of sewage sludge and calcium carbonate. The drawback of using organic matter is the risk that dissolved organic matter can act as a complexing agent for heavy metals and in this way increase their mobility. An additional study to examine this risk has therefore also been performed. The project started with a pilot study in order to identify the material fraction that was suitable for the experiment. When suitable material had been chosen, a column test was carried out for the purpose of studying the slurry’s influence on the mobility of metals along with the production of acidity. To clarify the organic material’s potential for complexation a pH-stat batch test was used. Drainage water samples, from the columns, were regularly taken during the experiment. These samples were analysed for pH, electrical conductivity, alkalinity, redox potential, dissolved organic carbon (DOC), sulphate and leaching metals. The effluent from the pH-stat-test were only analysed on a few occasions and only for metal content and change in DOC concentration. The results from the laboratory experiments showed that the waste rock from Ljusnarsberg easily leached large amounts of metals. The stabilization of the waste rock succeeded in maintaining a near neutral pH in the rock waste leachate, compared to a pH 3 leachate from untreated rock waste The average concentration of copper and zinc in the leachate from untreated waste rock exceeded 100 and 1000 mg/l respectively, while these metals were detected at concentrations around 0.1 and 1 mg/l, respectively, in the leachate from the treated wastes. Examined metals had concentrations between 40 to 4000 times lower in the leachate from treated waste rock, which implies that the stabilisation with reactive amendments succeeded. The long term effects are, however, not determined. The added sludge contributed to immobilise metals at neutral pH despite a small increase in DOC concentration. The problem with adding sludge is that if pH decreases with time there is a risk of increased metal leaching. / Gruvavfallet från Ljusnarsbergsfältet i Kopparberg anses utgöra en stor risk för människors hälsa och den omgivande miljön. En del av varpmaterialet, ofyndigt berg som blir över vid malmbrytning, utgörs av sulfidhaltigt mineral. Då varpen exponeras för luft och nederbörd sker en oxidation av sulfiderna, vilket kan ge upphov till surt lakvatten och läckage av tungmetaller. Syftet med arbetet har varit att karaktärisera varpen och försöka stabilisera den med en blandning bestående av mesakalk och avloppsslam, samt att undersöka risken med det lösta organiska materialets förmåga att komplexbinda metaller och på så vis öka deras rörlighet. Efter insamling av varpmaterial utfördes först en förstudie för att avgöra vilken fraktion av varpen som var lämplig för försöket. När lämpligt material valts ut utfördes kolonntest för att studera slam/kalk-blandningens inverkan på lakning av metaller, samt pH-statiskt skaktest för att bedöma komplexbildningspotentialen hos det organiska materialet vid olika pH värden. Från kolonnerna togs lakvattenprover kontinuerligt ut under försökets gång för analys med avseende på pH, konduktivitet, alkalinitet, redoxpotential, löst organiskt kol (DOC), sulfat och utlakade metaller. Lakvattnet från pH-stat-testet provtogs vid ett fåtal tillfällen och analyserades endast med avseende på metallhalter och förändring i DOC-halt. Resultatet från den laborativa studien visade att varpmaterialet från Ljusnarsberg lätt lakades på stora mängder metaller. Den reaktiva tillsatsen lyckades uppbringa ett neutralt pH i lakvattnet från avfallet, vilket kan jämföras med lakvattnet från den obehandlade kolonnen som låg på ett pH kring 3. Medelhalten av koppar och zink översteg under försöksperioden 100 respektive 1000 mg/l i lakvattnet från det obehandlade avfallet, medan halterna i det behandlade materialets lakvatten låg kring 0,1 respektive 1 mg/l. Av de studerade metallerna låg halterna 40-4000 gånger lägre i lakvattnet från den behandlade kolonnen, vilket innebär att slam/kalk-blandningen har haft verkan. Stabiliseringens långtidseffekt är dock okänd. Det tillsatta slammet resulterade inte i någon större ökning av DOC-halten i det pH-intervall som åstadkoms med mesakalken. Utifrån pH-stat-försöket kunde det konstateras att det tillsatta slammet bidrog till metallernas immobilisering vid neutralt pH, trots en liten ökning av DOC-halten. Om en sänkning av pH skulle ske med tidens gång föreligger dock risk för ökat metalläckage.

Throughout Central Florida surface water and ground water are decreasing in quantity and quality in part because of excess Nitrate and Phosphorus nutrients. Stormwater runoff serves as a medium for transport of Nitrate and Phosphorus to surface water and ground water. The goal of this experiment is assess the Nitrate and Phosphorus removal in stormwater using select media. The results of a literature search, batch test experimentation and column test experimentation are used to determine an optimal media blend that may be implemented in detention ponds to reduce Nitrate and Phosphorus. The extensive literature search revealed 32 different media that may be used to remove Nitrate and Phosphorus. Each potential media was qualitatively and quantitatively evaluated based on 5 criteria: 1) relevance, 2) permeability, 3) cost, 4) availability in Florida, and 5) additional environmental benefit. The top 7 performing media: Florida peat, sandy loam, woodchips, crushed oyster shell; crushed limestone, tire crumb and sawdust were selected for batch test experimentation. The aerobic conditions in batch test experimentation prohibited the growth of denitrifying bacteria, therefore media mixes were selected for column test experimentation based on Ammonia and Orthophosphate concentrations. Batch test experimentation showed the most effective media to be 50% sand, 30% tire crumb, 20% sawdust by weight (media mix 1) and 50% sand, 25% sawdust, 15% tire crumb, 10% limestone by weight (media mix 2). Media mix 1, media mix 2 and a control are tested in column test experimentation, where the control is site soil from Hunters Trace development in Ocala, Florida. Column test experimentation models a dry detention pond where water passes through a 48 inch unsaturated zone then a 48 inch saturated zone. To test Nitrate and Orthophosphate removal potential, pond water augmented with Nitrate (0.38, 1.26, 2.5 mg/L NO3-N) and Orthophosphate (0.125, 0.361, 0.785 mg/L PO4-P) was pumped into the columns. Media mix 1 and media mix 2 outperformed the control in both Nitrate and Orthophosphate removal. Media mix 1 and media mix 2 had Nitrate removal efficiencies ranging from 60% to 99% and the control had Nitrate removal efficiencies ranging from 38%-80%. Media mix 1 and media mix 2 averaged Orthophosphate removal efficiencies ranging from approximately 42% to 67%. For every run in every influent Orthophosphate concentration the saturated control added Orthophosphate to the water. The Nitrate and Orthophosphate removal performances for media mix 1 and media mix 2 could not be directly compared because of different influent saturated nutrient concentrations.

Organohalogen compounds are formed in swimming pool waters when natural organic matter, such as hair, urine or sweat etc., react with the used disinfectant (usually chlorine). Many of the organohalogen compounds are persistent and hazardous for human health and aquatic ecosystems. Backwash water from swimming pool facilities is often released to the sewer and contain these compounds. The connected wastewater treatment plant receives this water, where some of these compounds escapes the treatment process, into the recipient. It is therefore important to minimize the levels of organohalogen compounds in the influent water to the wastewater treatment plant. In this study, potential treatment techniques for organohalogen compounds at the swimming pool facility have been investigated. The main focus have been on an experimental column test with four filter materials applied (granular activated carbon, natural zeolites, PoloniteR and Zugol). Real backwash water was used. Furthermore, other techniques have been theoretically investigated as well. The activated carbon directly showed the most efficient removal efficiency (above 95 %), but all filter materials had a removal to a certain degree and became more efficient by time. The results further suggest that the more lipophilic organohalogen compounds are bound to particulate matter and highly affected by physical filtration. Another important conclusion is that the specific activated carbon used in the study is not suitable for the purpose, because it released very high levels of phosphorus in the beginning of the column test as well as showing some practical problems. However, other types of activated carbon exists. Next step recommended is to determine the lifetime of the filters. / När människor badar i bassänger hamnar vanligtvis naturligt organiskt material i dem, såsom urin, svett, hår och hudflagor. Desinfektionsmedlet som tillsätts (oftast klor) har som syfte att avlägsna mikroorganismer, men när naturligt organiskt material hamnar i vattnet kommer också oavsiktliga reaktioner ske och halogenerade organiska föreningar bildas. Dessa föreningar kan kvantifieras via AOX måttet (adsorberbar organisk halogen), vilket är den samlade förekomsten av alla bundna organiska halogener i ett prov. AOX består således av flera hundra olika föreningar, varav vissa är mer lipofila och benämns EOX (extraherbar organisk halogen). Många av de föreningar inkluderade i AOX är bioackumulativa, persistenta och giftiga för akvatiska organismer, även i låga koncentrationer. Förutom att vara miljöfarliga för akvatiska ekosystem, kan de också vara skadliga för människans hälsa. Filtret som renar badvattnet i simhallar behöver backspolas regelbundet och backspolvattnet, som innehåller AOX, skickas vanligen till spillvattennätet. Vid avloppsreningsverket är det visat i ett tidigare examensarbete samt i andra rapporter att en del av de inkommande AOX ämnena även följer med det utgående, renade, vattnet ut i recipienten. Det är därmed av vikt att minimera ämnena redan vid källan, det vill säga på badanläggningen. I denna masteruppsats har behandlingstekniker för halogenerade organiska föreningar undersökts. Huvudfokus har varit på experimentella kolonntester för fyra filtermaterial (granulerat aktivt kol, naturliga zeoliter, PoloniteR och Zugol), men även andra tekniker har studerats teoretiskt. I testerna användes äkta backspolvatten från en simhall. Alla material reducerade AOX till viss del och visade på effektivare reducering efter hand. Det var dock tydligt att det aktiva kolet var mest effektivt och hade hög reducering redan i första mätningen, AOX-reduceringen låg på över 95 % (jämfört med det obehandlade backspolvattnet). Vad som dock var problematiskt med det aktiva kolet var att det släppte höga halter fosfor i början av kolonntestet, vilket också bekräftades med ett skaktest. Dessutom uppvisade materialet praktiska problem. Ur ett realistiskt perspektiv med dessa problem i åtanke, blir det inte hållbart i längden att använda detta specifika kol. Det finns dock många olika typer av aktivt kol, vilka förmodligen är mer lämpliga och som inte uppvisar dessa problem, och kan användas för detta ändamål. Vidare antyder det erhållna resultatet att de mer lipofila föreningarna av AOX (EOX) är bundet till partikulärt organiskt material och därmed påverkas väsentligt av mekanisk filtrering. Det är dock viktigt med en aktiv bindning. Projektet har påverkats av covid-19 pandemin med lägre antal folk på badhusen samt mindre tillgång till laboratoriet vid KTH. En föreslagen förbättring av metoden är att ha en kontinuerlig omblandning i förvaringskärlet med det obehandlade vattnet innan det tillförs kolonnerna. Vidare nämns det att modifierade zeoliter verkar lovande samt att nästa viktiga steg för projektet är att bestämma livstiden för filtermaterialen.

Cold-formed steel roof truss systems that use complex stiffener patterns in existing hat shape members for both top and bottom chord elements are a growing trend in the North American steel framing industry. When designing cold-formed steel sections, a structural engineer typically tries to improve the local buckling behavior of the cold-formed steel elements. The complex hat shape has proved to limit the negative influence of local buckling, however, distortional buckling can be the controlling mode of failure in the design of chord members with intermediate unbraced lengths. The chord member may be subjected to both bending and compression because of the continuity of the top and bottom chords. These members are not typically braced between panel points in a truss. Current 2001 North American Specifications (NAS 2001) do not provide an explicit check for distortional buckling. This dissertation focuses on the behavior of complex hat shape members commonly used for both the top and bottom chord elements of a cold-formed steel truss. The results of flexural tests of complex hat shape members are described. In addition, stub column tests of nested C-sections used as web members and full scale cold-formed steel roof truss tests are reported. Numerical analyses using finite strip and finite element procedures were developed for the complex hat shape chord member in bending to compare with experimental results. Both elastic buckling and inelastic postbuckling finite element analyses were performed. A parametric study was also conducted to investigate the factors that affect the ultimate strength behavior of a particular complex hat shape. The experimental results and numerical analyses confirmed that modifications to the 2001 North American Specification are necessary to better predict the flexural strength of complex hat shape members, especially those members subjected to distortional buckling. Either finite strip or finite element analysis can be used to better predict the flexural strength of complex hat shape members. Better understanding of the flexural behavior of these complex hat shapes is necessary to obtain efficient, safe design of a truss system. The results of these analyses will be presented in the dissertation. / Ph. D.

Carbon –based engineered nanoparticles have been widely used due to their small size and uniquephysical and chemical properties. They can dissolve in water, transport through soil and reach drinkingwater resources. The toxic effect of engineered nanoparticles on human and fish cells has beenobserved; therefore, their release and distribution into the environment is a subject of concern. In thisstudy, two types of engineered nanoparticles, multi-walled carbon nano-tubes (MWCNT) and C60 withcylindrical and spherical shapes, respectively, were used. The aim of this study was to investigatetransport and retention of carbon-based engineered and natural nanoparticles through saturated porousmedia. Several laboratory experiments were conducted to observe transport behavior of thenanoparticles through a column packed with sand as a representative porous media. The columnexperiments were intended to monitor the effect of ionic strength, input concentration and the effect ofparticle shape on transport. The results were then interpreted using Derjaguin-Landau-Verwey-Overbeak (DLVO) theory based on the sum of attractive and repulsive forces which exist betweennanoparticles and the porous medium. It was observed that as the ionic strength increased from 1.34mM to 60 mM, the mobility of the nanoparticles was reduced. However, at ionic strength lower than10.89 mM, mobility of C60 was slightly higher than that of MWCNTs. At ionic strength of 60 mMMWCNT particles were significantly more mobile. It is rather difficult to relate this difference to theshape of particle and further studies are required.The effect of input concentration on transport of MWCNTs and C60 was observed in bothmobility of the particle and shape of breakthrough curves while input concentration was elevated from7 mg/l to 100 mg/l. A site-blocking mechanism was suggested to be responsible for the steep andasymmetric shape of the breakthrough curves at the high input concentration.Furthermore inverse modeling was used to calculate parameters such as attachment efficiency,the longitudinal dispersivity, and capacity of the solid phase for the removal of particles. The inversionprocess was performed in a way that the misfit between the observed and simulated breakthroughcurves was minimized. The simulated results were in good agreement with the observed data.