University of Macau / Faculty of Science and Technology / Department of Civil and Environmental Engineering

The aim of this report is to present a proposal for a constructed wetland as a complement toHaga treatment plants, Surahammar. First, a literature study in the subject was made andthen a case study was conducted, where Ekeby and Trosa wetland was visited. Parallel anarchival study was performed and several field visits were made to the proposed site toinvestigate the local conditions for constructing a wetland adjacent to Haga treatment plants.Finally, a proposal for the design of the constructed wetland was made. The proposalincludes an oxygenating area for reduction of ammonium to nitrate followed by a system ofdams and channels to convert nitrate to nitrogen diffuses into the air. Phosphorus removaltakes place throughout the residence time in the wetland, as well as reduction of the bacterialload. Expected results for the outgoing water from the wetland is that P-tot can be reduced to0.10-0.11 mg / l, N-tot can be reduced to 11-14 mg / l, a reduction of E. coli, fecal streptococciand intestinal streptococci by 70-99% and a little reduction of residues from drugs take placedue to oxygenation and the UV-irradiation of the water. / Allt vatten här på jorden ingår i den hydrologiska cykeln, så även det renade avloppsvattnet.Avloppsvatten innehåller bland annat kväve och fosfor vilka bidrar till övergödningen avsjöar, vattendrag och hav. Övergödningen är ett utbrett problem och i Västmanland är 53 %av länets sjöar och vattendrag utsatta för det.Syftet med den här rapporten är att ta fram ett förslag till våtmark för Haga reningsverk,Surahammar. Först har information om hur en våtmark kan användas för efterpolering avrenat avloppsvatten tagits fram för att därefter nyttjas som grund i ett förslag till våtmark förHaga reningsverk, Surahammar. Först gjordes en litteraturstudie inom ämnesområdet ochdärefter gjordes en fallstudie där Ekeby och Trosa våtmark besöktes. Parallellt utfördes enarkivstudie och flera områdesbesök på den tilltänkta platsen för att få fram vilkaförutsättningar som finns för att anlägga en våtmark i anslutning till Haga reningsverk ochsist gjordes ett förslag på en våtmark.Anledningen till att anlägga en våtmark kan vara flera, men att avskilja fosfor, kväve samtbryta ner organiskt material är vanliga orsaker. En våtmark fungerar som ett kompletterandesteg till det ordinarie reningsverket och minskar belastningen på recipienten. Hur mycketutsläppen reduceras beror på många faktorer och egenskaper där utformning, vattnetsuppehållstid, syresättning och tillgång till organiskt material är viktiga men även parametrarsom förbehandling av avloppsvattnet och belastningen på våtmarken spelar stor roll. Ävenväxtligheten i våtmarken påverkar det slutliga resultatet, både vad det gäller vad och hurmycket som avskiljs. Avskiljningen av fosfor och kväve sker främst genom sedimentation ochnäringsupptag till växter samt att kväve även avskiljs vid denitrifikation. För den långsiktigaavskiljningen av kväve från vattnets kretslopp är nitrifikation och denitrifikation de som harstörst betydelse. Nitrifikationsprocessen är när ammoniumjoner omvandlas till nitratjoneroch det kräver god tillgång på syre, därefter följer denitrifikationen när nitratjonerna undersyrefria förhållanden omvandlas till kvävgas som diffunderar upp i atmosfären. För attnitrifikationsprocessen ska kunna fungera krävs antingen att det finns ennitrifikationsanläggning i reningsverket eller en syresättningsfas i våtmarken. Det kan skapasgenom att börja våtmarken med en översilningsäng, där det renade avloppsvattnet får strilaner över en bevuxen äng. Vattnet syresätts av luften och nitrifikationsbakterier som trivs bra iväxtligheten utför nitrifikationsprocessen och omvandlar ammoniumjonerna till nitratjoner.Därefter följer ett system av dammar och kanaler där denitrifikationsprocessen tar vid ochomvandlar nitratjonerna till harmlöst kväve. Även i dammar och kanaler har växtlighetenstor betydelse eftersom det bildas biofilm, ett tunt lager av bakterier på växterna, som deltar iden biologiska processen av nedbrytning av organiskt material samt avskiljning av fosfor ochkväve i vattnet.När vattnet passerar genom våtmarken sker också en reducering av antalet bakterier somfinns i det renade avloppsvattnet. Mätningar av E. coli, fekala streptokocker, Koliformabakterier och intestinala enterokocker visar på att halterna kan reduceras kraftigt. Även vissaläkemedel visar tendenser till att brytas ned, men läkemedel är en komplex grupp och detfinns begränsad kunskap om deras omvandling och påverkan i miljön. Det finns dock indikationer om att nedbrytningen av läkemedelsrester är högre i de våtmarker som harsyresättande delar som till exempel översilningsäng.Haga reningsverk är beläget strax utanför Surahammars tätort och har idag en kulvert somleder ut det renade avloppsvattnet från verket till recipienten. Mellan Haga och recipientenligger ett markområde på cirka 750 gånger 750 meter som skulle kunna utnyttjas till envåtmark. Redan idag ligger utsläppsvärdena för Haga reningsverk under de tillåtna halternamen en önskan att ytterligare minska belastningen på miljön finns. Vid analysering avutsläppsvärden för Haga reningsverk framkom att ammoniumkväve utgör en stor andel avutgående totalkväve samt att halterna av totalfosfor, BOD7 och suspenderade ämnen är lågatill måttliga. Ett förslag på våtmark anpassat till de förutsättningar som råder vid Hagareningsverk har tagits fram och presenteras i rapporten. Våtmarken föreslås innehålla tvåsektioner med först en översilningsäng för att reducera den höga andelen ammoniumkväveoch därefter ett damm och kanalsystem för att reducera nitratkvävet. Under hela processensker avskiljning av fosfor samt reducering av bakterier och en viss nedbrytning avläkemedelsrester. Förväntade resultat för det utgående vattnet från våtmarken är att P-totkan reduceras till 0,10–0,11 mg/l, N-tot kan reduceras till 11–14 mg/l, en reducering av E.coli, fekala streptokocker och intestinala streptokocker med 70-99 % samt att en vissminskning sker av läkemedelsrester tack vare syresättning och solens UV-bestrålning avvattnet.

The reduction of sulphur in transportation fuel has gained significant importance as the regulatory agencies worldwide react to air quality concerns and the impact of sulphur oxides on the environment. The overall objective of this research was to identify, develop and characterize, based on underlying scientific principles, sorbents that are effective in removal of refractory sulphur compounds from fuel through the process of selective adsorption. It was determined that impregnation of powdered activated carbon with a transition metal (TM) significantly boosted the adsorption performance of the activated carbon. It is hypothesized that the impregnation resulted in the formation of new adsorptive sites that strongly interacted with the lone pairs of electrons on sulphur and nitrogen while having minor impact on the existing oxygen functional groups on the surface of the activated carbon. The percent loading of the TM was determined through wet adsorption study. The best performing sorbent was shown to have maximum adsorption capacities of approximately 1.77 and 0.76 mmol-S/g-sorbent for DBT and 4,6 DMDBT, respectively, with approximately 100% regenerability through solvent wash and thermal treatment. On average, the PTM impregnation showed approximately 137% increase in adsorption capacity of the activated carbon. The sorbent also has good adsorption capacities for organo-nitrogen compounds (i.e., quinoline and carbazole) and a low selectivity towards aromatics, which is desired in adsorptive desulphurization. The surface morphology of the activated carbon, the oxygen functional groups on the surface of the activated carbon, as well as strong (chemisorption) interaction between the TM???s partly vacant and far reaching ???d??? orbital and lone pair electrons on sulphur and nitrogen are considered to be the main contributing factors to the observed enhancement. It was established in this study that the adsorption isotherms of the impregnated activated carbons best fit Sips isotherm equation, which is a combination of the Langmuir and Freundlich equations. This finding fits well with our initial hypothesis regarding the introduction of new adsorptive sites as a result of TM impregnation and that the sites did not fit well with Langmuir???s monolayer and uniform adsorption mechanism. A kinetic study of the sulphur adsorption using a flow reactor showed a good fit with pseudo second order kinetic model, indicative of an adsorption that is highly dependent on the concentration of available sites on the surface of the sorbent. On average, as expected, the TM impregnated ACC exhibited a higher initial rate of adsorption. The adsorption onto TM sites tends to be more exothermic than adsorption (mainly physisorption) on activated carbon. Therefore, more thermodynamically favoured chemisorption is expected to occur more rapidly than physisorption. It was determined that on average, the initial adsorption rate does not change significantly with temperature while the sulphur adsorption capacity decreases with increase in temperature. It is postulated that the increase in temperature increases surface diffusivity but impedes diffusion flux. The impediment of the diffusion flux will result in reduction in adsorbed quantity. It was also shown that the intra-particle diffusion exists in the adsorption of DBT on TM impregnated activated carbon, however, it is not likely that the overall adsorption is controlled or noticeable impacted by it. As the temperature of the reactor increases the Weber-Morris intra-particle diffusion plot moves away from the origin, and thus intra-particle diffusion becomes less of a controlling mechanism. This further confirms the fact that the boundary layer (i.e., surface diffusion) and potentially adsorptive interactions at the surface are the dominating mechanisms in the sulphur adsorption onto TM impregnated activated carbon. It was determined that the distribution of TM species on the surface of the activated carbon is relatively inhomogeneous, with some areas showing well dispersed TM species while other areas showing large clusters. Different impregnation method that can improve dispersion on the surface may significantly enhance adsorption performance of the sorbent. Furthermore, in this study impregnation of activated carbon using several other transition metals were examined. It was determined that other less expensive transition metals can also improve the adsorption performance of the activated carbon. Further study on less expensive options for impregnating the activated carbon may be beneficial.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Apesar da importÃncia do saneamento ambiental para o bem-estar do homem e para a conservaÃÃo dos recursos naturais, uma grande parcela da populaÃÃo mundial nÃo tem acesso aos serviÃos bÃsicos de saneamento. A disposiÃÃo no solo hà muitos anos mostra-se como opÃÃo para tratamento e pÃs-tratamento de efluentes domÃsticos, sendo que a recusa por grande parte da populaÃÃo reside da ignorÃncia e da falta de informaÃÃes adequadas quanto Ãs formas de reÃso que podem ser oferecidas. O escoamento superficial mostra-se simples quanto à construÃÃo e operaÃÃo, bem como a produÃÃo vegetal obtida com esse tipo de sistema. Foi testada a grama Tifton 85(Cynodon sp), pois possui grande adaptaÃÃo a condiÃÃes de altas concentraÃÃes de nutriente e umidade, mostrando-se como opÃÃo viÃvel para cultivo em rampas de escoamento superficial. O experimento foi realizaÃÃo no Centro de ReÃso da CAGECE localizado na EstaÃÃo de Tratamento de Efluentes da cidade de Aquiraz, CearÃ. Foram construÃdas trÃs rampas de escoamento superficial com inclinaÃÃes diferentes, 2%, 4% e 6% com 30 metros de comprimento e 10 metros adicionais na rampa de 6% de inclinaÃÃo. O lÃquido aplicado nas rampas era esgoto sanitÃrio tratado, proveniente de lagoa de maturaÃÃo. As taxas de aplicaÃÃo de esgoto testadas foram 0,2m3/m.h, 0,3 m3/m.h e 0,4 m3/m.h. Avaliou-se a capacidade do sistema em remover nutrientes, nitrogÃnio e fÃsforo, bem como matÃria orgÃnica. Com a realizaÃÃo de anÃlises quantitativas foi possÃvel determinar qual inclinaÃÃo permitia maior remoÃÃo e em qual vazÃo de operaÃÃo. Para taxas de 0,2m3/m.h, 0,3 m3/m.h a rampa com 2% de inclinaÃÃo alcanÃou 57,65% e 57,11% de remoÃÃo de matÃria orgÃnica respectivamente. Em termos de remoÃÃo de nitrogÃnio a rampa com 6% teve melhor desempenho. O sistema tambÃm apresentou remoÃÃes significativas de microalgas, avaliados em termos de clorofila-a. Em todos os aspectos analisados, o sistema melhorou a qualidade final do efluente, mostrando-se como alternativa viÃvel, com tÃcnica simples e barata compatÃvel com a realidade econÃmica do nordeste brasileiro

Call number: LD2668 .T4 1965 H36 / Master of Science

To reduce energy consumption, and to achieve the desired denitrification, the activated sludge process sometimes needs to operate at low dissolved oxygen concentrations. The ASM2d model describes the activated sludge process, if nitrification and denitrification occur during different phases in a sequencing batch reactor (SBR). Despite the widespread study of enhanced biological phosphorous removal, comprehensive sludge floc distribution model remains lacking that would better describe this process. Consequently, the integrated system model has been developed to understand the impact of floc at low DO concentrations, and during the process of biological nitrogen and phosphorous removal. In a wastewater treatment plant used in this study, the dissolved oxygen was controlled at a low concentration, 1.7〖gO_2 m〗^(-3), and the dispersion coefficient into the floc was found to be 〖D=1.2×10〗^(-4) m^2/day. Introduction of a number of effectiveness factors contributed to the development of the ASM2d model described herein. This developed model could be valuable for predicting process behaviours applicable under various configurations. Moreover, parameters and effectiveness factors for the model could be calibrated using a genetic algorithm approach. Optimisation was then achieved by controlling the solids retention time during the activated sludge process.

published_or_final_version / Civil and Structural Engineering / Master / Master of Philosophy

No description available.

2 pp. / Persistent woody plants can sometimes conflict with gardening and landscape goals. In many cases, plant removal becomes necessary. This may be accomplished through manual stump removal or the use of herbicides. With some knowledge of the life history of the target plant, cut stumps can be safely and effectively treated with herbicides to prevent regrowth. Species lists, safety tips, examples, photos, and non-herbicide alternatives are provided to ensure optimum stump killing success.

Effects of several important source-related and operation-related factors on particle formation and growth as well as potential particle and dissolved organic matter removal by alum coagulation are described. Two representative natural water sources, with low turbidities and high concentrations of dissolved organic matter, and one commercially available crystalline silica, with defined characteristics, were employed to establish initial aquatic particle and dissolved organic matter conditions. Six experimental variables utilized for evaluation include initial pH, initial turbidity, applied pre-ozonation dose, alum dose, flocculation time and sedimentation time. A bench-scale experimental apparatus with capabilities of ozonation, coagulation, sedimentation and membrane filtration was employed to conduct a series of selected experiments. Each factor investigated in this research proves to be able to inpart, individually or collectively, statistically significant effects on particle formation and growth during alum coagulation. While the addition of model particles shows significant enhancement in particle growth, it fails to demonstrate significant improvement in the removal of dissolved organic matter. On the contrary, effects of pH and alum dose on particle formation and growth are accompanied by corresponding effects on the removal of dissolved organic matter. Pre-ozonation of dissolved organic matter renders the dissolved organic matter more hydrophilic by increasing the number of carboxylic acid functional groups. This phenomenon can significantly improve or impede particle growth as well as dissolved organic matter removal during alum coagulation, depending on raw water chemistry and other operational factors. Alum coagulation under all of the conditions investigated in this research is demonstrably more effective in removing aquatic humic susbtances with higher apparent molecular weights and fewer carboxylic acid functional groups, as opposed to those with lower apparent molecular weight and more carboxylic acid functional groups. The predominant removal mechanisms were found to occur at the beginning stage of the coagulation process; that is, the rapid mixing period. The remaining dissolved organic matter and humic substances can form significant amounts of trihalomethanes upon reaction with chlorine.