This is a project about The Water Treatment System at Djupdalen. The leakage water comes to the Water Treatment System from a deposition plant through the land. The leakage water is characterized by a high concentration of nitrogen and the system is based on biological removing of the nitrogen in the water, by nitrifying and denitrifying bacteria. Four different problems are found in the system: 1. High level of nitrogen concentration in the outgoing water of the system. It should be due to the lack of phosphate in the water, that do not let the bacteria to grow. 2. Low temperature during the most part of the year. Nitrifying and denitrifying bacteria are temperature-dependent, that are very slow at low temperatures. 3. High oxygen concentration in one of the anoxic pond, where the denitrification process take place. This oxygen concentration is too high for denitrifying bacteria to work. 4. The nitrification and denitrification bacteria need to be “old” to work efficiently. They need a surface to attach, because if not they flow with the water and they leave the system. And four possible solutions for the system are presented: 1. Phosphate should be added to the system to let bacteria growth. 2. Store the water at a store pond during the winter months and transport it to the system when the temperature is optimum for the bacteria to work. 3. Add carbon matter to improve the carbon oxidation and to low down the oxygen levels at the anoxic ponds. 4. Two options are presented to improve the system, the first one is based on the construction of a dark wavy bottom in the channel system, which will give a surface for bacteria to attaché, it will produce oxygenation in the water, and it will also improve the water temperature; and the second one is based on the addition of panels made of black material, which will give to bacteria a surface to attach, and improve the water temperature.

This research focuses on anoxic ammonium oxidation (anammox). The anammox process for treating high ammonium and low organic carbon wastewater can reduce operational costs to a greater extent than the conventional autotrophic/heterotrophic treatment process can. The process has been widely researched because of its potential economic benefits. However, during long-term reactor operation, sudden reductions of nitrogen removal rates have been reported; maximum nitrogen removal rates in different reactor configurations could not approach values predicted based on mathematical modeling; and the crucial stability parameter, such as nitrite, did not have defined threshold concentration. It was hypothesised that free ammonia (FA) increase is the precursor of the instability of the anammox reactor. If it is true that nitrite up to about 200 mg N/L should stimulate nitrogen removal rate inside of the anammox reactor, when FA is kept below the inhibition threshold concentration. The research presented in the thesis argues that FA plays a larger role than has been previously considered in the instability of the anammox reactor. This study found FA inhibited nitrogen removal rates (NRR) at concentrations exceeding 2 mg N/L. In the pH range 7 to 8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 200 mg N/L did not negatively affect nitrogen removal rate. This study further found that low nitrite provided stable anammox reactor performance, but that high nitrite was not necessarily the cause for reactor destabilization. During the research high nitrogen removal rate was achieved when low FA was provided. During regular reactor operation at pH 6.5, the NRR at about 6.2 g N/Ld was archived. This value was never achieved before till this study was conducted. Conducted research showed controlling FA at low level is required to approach high rates in anammox reactors. Achieving high rates in anammox reactors allow significant reduction in reactor volume which saves resources. Further studies will be required to identify the FA effect on different microbial interactions, and that may provide more in-depth understanding of the nitrite and FA effect than observations based on NRR alone.

This research focuses on anoxic ammonium oxidation (anammox). The anammox process for treating high ammonium and low organic carbon wastewater can reduce operational costs to a greater extent than the conventional autotrophic/heterotrophic treatment process can. The process has been widely researched because of its potential economic benefits. However, during long-term reactor operation, sudden reductions of nitrogen removal rates have been reported; maximum nitrogen removal rates in different reactor configurations could not approach values predicted based on mathematical modeling; and the crucial stability parameter, such as nitrite, did not have defined threshold concentration. It was hypothesised that free ammonia (FA) increase is the precursor of the instability of the anammox reactor. If it is true that nitrite up to about 200 mg N/L should stimulate nitrogen removal rate inside of the anammox reactor, when FA is kept below the inhibition threshold concentration. The research presented in the thesis argues that FA plays a larger role than has been previously considered in the instability of the anammox reactor. This study found FA inhibited nitrogen removal rates (NRR) at concentrations exceeding 2 mg N/L. In the pH range 7 to 8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 200 mg N/L did not negatively affect nitrogen removal rate. This study further found that low nitrite provided stable anammox reactor performance, but that high nitrite was not necessarily the cause for reactor destabilization. During the research high nitrogen removal rate was achieved when low FA was provided. During regular reactor operation at pH 6.5, the NRR at about 6.2 g N/Ld was archived. This value was never achieved before till this study was conducted. Conducted research showed controlling FA at low level is required to approach high rates in anammox reactors. Achieving high rates in anammox reactors allow significant reduction in reactor volume which saves resources. Further studies will be required to identify the FA effect on different microbial interactions, and that may provide more in-depth understanding of the nitrite and FA effect than observations based on NRR alone.

A presente dissertação apresenta e discute os resultados do trabalho experimental cujo objetivo foi avaliar a remoção de nitrogênio na forma de mitrato (N-NO3-) pelo processo de desnitrificação biológica em reator anóxico horizontal de leito fixo (RAHLF) contendo matrizes de espuma de poliuretano, em escala de laboratório, utilizando gás metano como fonte de carbono e único doador de elétrons adicionado ao sistema. Para concentrações iniciais de N-NO3- de 20 mg/L e 40 mg/L no substrato sintético, foi possível obter diminuição das concentrações iniciais em 85% e 50%. No entanto, os altos níveis de redução de N-NO3-, obtidos sob condições limitantes de metano, deram suporte à hipótese de que parte da remoção do N-NO3- foi realizada mediante a utilização de compostos reduzidos de enxofre ou nitrogênio, tais como: S0, HS- ou NH4+, provavelmente formados sob condições anóxicas, simultaneamente com o processo de desnitrificação. Foi possível verificar, também, a influência da relação carbono (mg/L CH4 / nitrogênio (mg/L N-NO3-) no estabelecimento das rotas metabólicas de desnitrificação predominantes, quais sejam, a redução dissimilativa do nitrogênio à amônia (RDNA) ou a desnitrificação. Adicionalmente, foram realizados ensaios em reatores tipo batelada, com o objetivo de se medir o consumo de metano. Porém, os resultados não foram satisfatórios, provavelmente em razão da diversidade microbiana presente no inóculo. Foram realizadas análises de microscopia óptica e de fluorescência, assim como de DGGE, para avaliar a diversidade e as alterações nas populações microbianas ao longo do RAHLF e do tempo de experimento. Os diferentes sistemas utilizados apresentaram limitações relacionadas à baixa solubilidade do gás metano no meio líquido, à resistência à transferência de massa da fase gasosa para a líquida e desta última para a biomassa aderida à espuma. / This study presents and discusses experimental work results conducted with the purpose of evaluating nitrate - nitrogen (N-NO3-) removal by biological denitrification process in a lab scale horizontal flow fixed bed anoxic reactor (RAHLF), using methane gas as sole carbon source and electron donor. Support media for microorganisms were polyurethane foam matrixes. For initial N-NO3- concentrations of 20 mg/L and 40 mg/L present in synthetic substrate, it was possible to obtain 85% and 50% removal respectively. These high reduction rates, obtained under limiting conditions of methane, sustained the idea of part of the N-NO3- removal being accomplished by reductive sulfur or nitrogen species utilization, such as: S0, HS- or NH4+, probably formed under anoxic conditions simultaneously to denitrification process. It was possible to verify also carbon (mg/L CH4) / nitrogen (mg/L N-NO3-) ratio effect in denitrification metabolic paths establishment, i.e. dissimilative reduction of nitrogen to ammonia or denitrification itself. In addition, batch tests where conducted with methane consumption measuring purpose. Yet, results where not satisfactory probably due to great microbial diversity present in inoculum. Optical microscopy and fluorescence exams where developed, as well as, DGGE, in order to evaluate diversity and alterations in bacterial populations as a function of reactor\'s length and time. Different systems used in experimental work presented limitations due to low methane gas solubility in bulk liquid and mass transfer resistance from gas to liquid phase and from this to fixed biomass.

This thesis examines the effect of solids recycling on nitrification, organic carbon removal, and algal-bacterial productivity in bench-scale photobioreactors (PBRs) simulating winter pond conditions in San Luis Obispo, California and a 6-acre raceway system in Delhi, California. Two sets of duplicate photobioreactors operated with or without solids recycling were fed primary clarifier effluent (1oEff) for the first experiment, and facultative pond effluent (FAC) for the second experiment. In both experiments mean productivity was lower in solids recycled PBRs (3.67 and 2.3 g/m2-day), than in controls without solids recycling (4.15 and 3.9 g/m2-day). When fed 1oEff which contained a high amount of readily biodegradable COD, solids recycled PBRs had 30% less VSS in supernatant than controls after 1 hour of settling in Imhoff cones. However, when fed facultative pond water with no readily biodegradable COD there was little difference in supernatant VSS after settling. The type of wastewater influenced COD removal. PBRs had 40-50% soluble COD removal when fed 1oEff, and 10-20% removal when fed FAC. Mean PBR effluent COD was the same in both treatments and controls in when fed 1oEff (42 mg/L). When fed FAC mean effluent COD was marginally lower in solids recycled PBRs (61 mg/L) then in controls (68 mg/L). Most of the COD in 1oEff was readily biodegradable, while most of the COD in FAC was degraded while in facultative ponds leaving mostly recalcitrant and slowly biodegradable COD in FAC. Nitrification occurred more quickly and more reliably in solids recycled PBRs. The difference in nitrification was seen most notably when using FAC as PBR influent, where solids recycled PBRs had complete nitrification, but controls did not. When fed 1oEff all PBRs had complete nitrification, but solids recycled did so sooner. Overall, PBRs with solids recycling were also more resilient to changes in influent wastewater characteristics and had more consistent effluent water quality when fed wastewater that had occasional spikes in nitrogen and organic carbon. The difference between the two wastewaters indicates a possible inhibitory effect of FAC on nitrification. Microscopy data from both studies, though mostly qualitative, seems to indicate that solids recycling promotes biodiversity in algal-bacterial cultures, which may be part of the reason why solids recycling promoted more resilient and reliable treatment.

The combination of partial nitritation and anaerobic ammonium oxidation (Anammox) is a composting way to remove the nitrogen in the wastewater. In this article the analysis was made to investigate how the salinity in the wastewater affects the process. Two strategies of salt concentration increase were tested in two reactors. The physical, chemical parameters and the activity of the bacteria in the reactors were monitored. The results of two strategies were compared and the reactor with less salt in each period showed higher bacteria activities and efficiency. Finally the outlook for the future research was made.

Regions with a cold winter, as in the Baltic countries, have a problem to meet the nitrogen requirement in the Urban Wastewater Treatment Directive 98/15/EC. Especially in the winter season, the temperature of the influent wastewater could arrive also below 10°C and this delays the biological processes that takes place in the wastewater treatment. With the decrease of the temperature, the efficiency of nitrogen removal in the system decreases and leads to a high nitrogen loading in the effluent. The ITEST (Increased Technology and Efficiency in Sewage Treatment) project situated in Hammarby Sjöstadsverk in Stockholm has as its main aim to enhance nitrogen removal, thereby increasing the temperature in the incoming wastewater. The pilot plant ITEST is comprised of two treatment lines, one works with natural temperature influent and the other works at the temperature of 20 °C. In order to warm the incoming water a heating system, using waste heat, is used, leading to save energy. The two test lines were compared analyzing different parameters from January to May 2013. Total nitrogen, nitrate-nitrogen and ammonium-nitrogen concentrations were measured in the incoming water and in the effluent from the two treatment lines. Hence, the efficiency of the nitrogen removal was compared between the reference and the temperature line. In the period where the system was well functioning, the results show a nitrogen efficiency with a maximum of 92 % of removal of total nitrogen for the temperature line compared to only 65 % for the reference line. In the period where the system did not have any troubles the total nitrogen is under 10 mg/l, which is the limit of total nitrogen discharges specified in the Directive. Instead, for the sludge volume and the suspended solids any particular difference can be noticed from the two lines of treatment. In conclusion, in the temperature line can be noticed a great efficiency in nitrogen removal compared to the reference line.

The impending change of processes at SSAB Oxelösund due to the HYBRIT project, where the blast furnace and LD converter are to be replaced with an EAF will have a significant impact on the manufacturing of steel in Oxelösund. One issue that will arise is the nitrogen content in the steel. Sources claim that the nitrogen content in steel from an EAF route is substantially larger, 60-70 ppm, than in steel from a blast furnace and LD converter route, which have a nitrogen content of around 25 ppm. Therefore, the nitrogen removal capabilities of SSAB Oxelösund’s vacuum tank degasser were to be examined. Industrial trials were performed where the amount of slag during vacuum treatment was lowered. The intention was that half the amount of slag removed prior to vacuum treatment and later completely slag free. This was performed in an attempt to increase the effective reaction area, where nitrogen removal occurs. Due to some practical problems with the steel mill, the industrial trial were unfortunately cut short. Consequently, only trials with half the amount of slag were performed and compared to existing process data for standard praxis. Also, nitrogen removal calculations based on the industrial data were performed. A parameter representing the overall reaction rate, which is dependent on effective reaction area was obtained, validated and subsequently applied to a future case scenario. The results indicate that the reduction in slag amount does have the desired effect, increasing the said area and increasing the rate of nitrogen removal. However, the sample size is not nearly sufficient enough to determine this definitively. The conclusions reached were that the facility does have the possibility to decrease the increased nitrogen content down to reasonable levels, around 20-30 ppm. Albeit, an increase in vacuum treatment time is probably required. Another conclusion was that surface active elements, such as oxygen and sulphur greatly reduce the nitrogen removal. Therefore, efforts should be taken to remove these elements prior to vacuum treatment. In addition, it was established that the effective reaction area is of great importance for a successful nitrogen removal. Therefore, actions to maximise this area should be taken. Finally, it was stated that further research is necessary in order to fully understand nitrogen contamination prevention- and removal techniques / Förändringar till följd av HYBRIT projektet kommer påverka SSAB Oxelösunds stålverk. Masugn och LD konverter skall ersättas med ljusbågsugns teknologi. Ett problem till följd av detta är kvävehalter i stålet. Enligt litteraturen är kvävehalterna betydligt högre i stål tappat från en ljusbågsugn. Med kvävehalter runt 60-70 ppm jämfört med stål tappat från en LD konverter som har kvävehalter kring 25 ppm. Därför krävdes en undersökning kring kvävereningpotentialen för SSAB Oxelösunds vakuum tank avgasare. Industriella experiment med minskad slaggmängd jämfört med standard praxis blev utförda. Detta utfördes med tanken att minskad slaggmängd skulle ge en större effektiv reaktionsarea. Intentionen var att utföra försök först med halverad slaggmängd följt av slaggfria försök. Dock, på grund av produktions praktiska problem vid verket blev försöken avbrutna. Som en följd av detta blev bara försök med halverad slaggmängd utförda och jämförda med processdata från standard praxis. Kvävereningsberäkningar på historisk processdata utfördes. En parameter som representerade genomsnittlig reaktionshastighet, vilken beror på den effektiva reaktionsarea blev erhållen, validerad och senare applicerad på ett hypotetiskt framtida scenario. Resultaten indikerar att minskad slaggmängd har en positiv inverkan på den effektiva reaktions arean och till följd av detta även en positiv inverkan på kväverening. Dock är för få försök utförda för att kunna fastställa detta. De slutsatser som dras är att vakuum anläggningen vid SSAB Oxelösund har möjligheten att, med förlängd vakuumbehandlingstid, rena de ökade kvävehalter till nivåer runt 20-30 ppm. Ytterligare slutsatser var att ytaktiva element, såsom syre och svavel, i stålet har en stor negativ påverkan för kväverening. Samt att den effektiva reaktionsarean är av stor betydelse för kväverening. Därför bör ansträngningar tas för att minska koncentrationen av ytaktiva element samt att försöka göra den effektiva reaktionsarean så stor som möjligt. Slutligen fastställdes det att ytterligare studier är nödvändiga för att öka kunskapen kring förebyggande tekniker och reningstekniker för kväveföroreningar i stål.

This study involved the use of soil and suspended growth microcosms to study the variation in groundwater denitrification rates using different substrates. Two gaseous substrates, carbon monoxide and methane, were studied and compared to a common liquid substrate, methanol. Denitrification with carbon monoxide as a substrate was achieved using an acclimated seed of mixed activated sludge and anaerobic digester sludge. Kinetic studies of denitrification using carbon monoxide suggested a strong substrate inhibition effect. The observed maximum denitrification velocity of 0.026 mg N/d-mg VSS occurred at a carbon monoxide partial pressure of 0.10 atmospheres (2.8 mg/ℓ). At higher carbon monoxide partial pressures, denitrification velocities decreased. The denitrification velocities at various carbon monoxide concentrations were described by a modified form of the Haldane substrate inhibition model. The biomass yield using carbon monoxide was 1.1 mg VSS/mg VSS, the maximum specific growth rate was 0.03 mg VSS/d-mg VSS, and the half velocity constant was 26 mg-N/ℓ. Denitrification rates using carbon monoxide as a substrate were much slower than those obtained using methanol, and the cost of carbon monoxide was much higher. Denitrification occurred readily, when methanol was provided as a substrate, in microcosms containing either a clay soil, a sandy soil, or activated sludge. Under the conditions of this study, denitrification was not achieved in clay soil or sandy soil microcosms using methane or carbon monoxide as substrates. Denitrification was not achieved using methane as a substrate with an activated sludge seed. / Ph. D.

No description available.