The effects of iron, temperature, and presence of botulinal spores or sodium ascorbate on depletion of nitrite level were determined in meat and model systems. Higher temperature and presence of botulinal spores definitely increased nitrite depletion in a meat system. Added hemoglobin also significantly increased nitrite depletion, while ferrous iron and ferric iron did not significantly decrease nitrite level in a meat system. High temperature and presence of sodium ascorbate increased nitrite depletion in a model system. Only ferrous iron significantly decreased nitrite level in the absence of ascorbate, while ferric iron, heme iron, and ferritin iron did not decrease nitrite level in the absence of ascorbate. Ferrous iron, ferric iron, and heme iron decreased nitrite level in the presence of ascorbate, while ferritin iron did not decrease nitrite level in a model system.

Nutrients are introduced into the waters of the Commonwealth of Pennsylvania through various methods, mainly through point and non-point sources. Non-point sources would include agricultural means however, there are often other non-point sources that are often overlooked. Water runoff from stormwater is an important contributor to pollution entering various watersheds. Data was collected at 4 locations (the initial point of reference, residential, urban, and industrial) on Mill Run and 2 locations on Woodcock Creek, through surface water collection methods in dry and wet weather. Nitrate, Nitrite, Total Phosphorus, and Total Nitrogen were among the data collected. Total Phosphorus had an increasing trend in concentration as the study progressed. Nitrate, Nitrite and Total Nitrogen showed no increasing trends. Location 3 (Urban Zone) produced the largest increase in Total Phosphorus. Weather conditions played a role in higher Nitrate concentrations while warm water produced higher Nitrite concentrations

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20009号 / 農博第2193号 / 新制||農||1045(附属図書館) / 学位論文||H28||N5018(農学部図書室) / 33105 / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 小川 順, 教授 阪井 康能, 教授 栗原 達夫 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

No description available.

The study is about Nitrogen removal from the low concentrated mainstream wastewater after Upflow Anaerobic Sludge Blanket reactor process (UASB) by single-stage Partial Nitritation/Anammox process in a pilot scale reactor at Hammarby Sjöstad in Stockholm. A mixture of various concentrations of dissolved oxygen and different aeration methods have been tested in the pilot scale reactor in five months divided into five periods where the temperature was set at 15° C throughout the study. The best result was in period 4, the average nitrogen removal efficiency was 52% varying between 40 and 60 % with aeration method of the ratio R = 1/3 (R = 20 minutes with aeration to 40 minutes without aeration) and a dissolved oxygen concentration of 1.3 mg/L. Partial nitritation/Anammox is considered more environmentally friendly due to reduced energy requirements for aeration, no need for an external carbon source. The process also allows for a more cost-effective nitrogen removal from wastewater. / Vatten är nödvändigt för existensen av allt liv på jorden och spelar en avgörande roll i alla mänskliga aktiviteter. Antropogena aktiviteter förorenar denna viktiga resurs och medför stor risk för människors och djurs hälsa samt växter. Kvävebelastning från jordbruket och avloppsvatten i mark- eller vattenmiljön har resulterat till övergödning, vilket är ett miljö- och ekonomiskt problem på grund av en obalans mellan ekosystemtillförseln och den naturliga näringsförbrukningen. I denna studie behandlades avloppsvatten i en pilotskala reaktor med en integrerad fastfilm aktiverat slam (IFAS) som drivs med ett enstegs partial nitritation/Anammox-process. Kväverening från den lågkoncentrerade huvudström avloppsvatten efter Uppflöde Anaerob Slam Blankett reaktor process (UASB) undersöktes. En blandning av olika koncentrationer av upplöst syre och olika luftningsmetoder har testats i pilotskala reaktorn i fem månader uppdelad i fem perioder där temperaturen sattes vid 15° C under hela studien. De bästa resultaten i kväve reningseffektivitet var 52 % i genomsnitt i period 4 varierande mellan 40 och 60 %, luftningsmetod med ett förhållande av R = 1/3 (R = 20 minuter med luftning till 40 minuter utan luftning) och ett upplöst syre Koncentration av 1,3 mg/l. Jämförelsen tog hänsyn till alla former av utsläpp av kväve- och energikostnader för luftning. Under de senaste decennierna har vattenbehandlingsprocesserna haft många positiva utvecklingar, vilket har lett till en kvalitetsförbättring av vatten samtidigt som kostnaden för kväveavlägsnande från avloppsvatten har minskat. För närvarande flyttar kvävereningsteknik från konventionell nitrifikations/denitrifikationsprocessen till partiell nitritation/Anammox (PN/A) -processen kallad deammonification. Det verkar som om den största svårigheten är att upprätthålla en stabil ackumulation av nitrit medan man försöker delvis med nitritation av ammonium. Partiell nitritation/Anammox (PN/A) anses vara mer kostnadseffektivt avlägsnande av kväve från avloppsvatten, mer miljövänligt än konventionella nitrifikations-denitrifikationsprocesser på grund av minskat energibehov för luftning och inget behov av en yttre källa av kol.

In order to meet increasingly stringent total nitrogen limits, supplemental carbon must be added to improve the performance of the biological nutrient removal process. An industrial by-product that contained ethylene glycol and propylene glycol was used as a substitute carbon source for methanol in this study. The objectives of this study were to investigate the efficiency of using the glycol mixture as carbon source, including the calculation of denitrification rate and yield at two different initial concentrations of glycols. Possible inhibition effect on nitrification was also investigated. Three SBR reactors were operated by adding methanol, a low dosage of glycol, and a high dosage of glycol into the reactors. The low dosage glycol reactor exhibited the best performance, with the highest denitrification rate of 11.55 mg NOx-N/g MLVSS"h and the lowest yield of 0.21 mg VSS/mg COD. Small nitrite accumulation was observed in the low dosage glycol reactor (COD=185"•15 mg/L), but effluent quality was not influenced. Excess glycol in the reactor caused deteriorated performance. The high dosage glycol reactor (COD=345"•20 mg/L) performed with the lowest denitrfication rate of 8.56 mg NOx-N/g MLVSS"h and the highest yield of 0.55 mg VSS/ mg COD. The reactor with the high dosage of glycol also inhibited the lowest nitrification rate of 1.15 mg NH3-N oxidized/g MLVSS"h, which indicated that excess glycol may cause nitrification inhibition. / Master of Science

Due to the adverse effects of ammonia on the environment, many governments, including Canada, have imposed new regulations to reduce the discharge of ammonia wastewater effluent into natural receiving waters, which has resulted in the upgrade of ammonia removal at water resource recovery facilities (WRRFs) across the world. There is therefore a need to investigate present urban/peri-urban and rural challenges associated with municipal total ammonia (TAN) removal. In particular, there is a need to further advance and optimize technologies such as the moving bed biofilm reactor (MBBR) to meet these critical challenges. The first objective of this thesis is to validate an elevated loaded strategy for partial nitritation (PN) MBBR as an application for mainstream urban and peri-urban municipal wastewater treatment and to elucidate the mechanism of nitrite-oxidation suppression of this system. The second objective is to identify practical storage strategies for nitrifying MBBR units as rural municipal wastewater upgrade systems (lagoon systems), optimizing the TAN removal performance during seasonal discharge periods. In the context of the present climate change crisis and sustainable development requirements, there is an increased need for efficient TAN removal from urban and peri-urban municipal wastewaters. The application of the energy and cost-efficient partial nitritation/anammox (PN/A) technology to mainstream urban and peri-urban municipal wastewater can prove challenging because of limited ability to achieve the stable PN. Hence, there is a need for the validation of the present strategies for achieving effective and stable PN in the mainstream portion of conventional urban and peri urban WRRFs. The 45 days operation of a laboratory-scale, elevated loaded PN MBBR with average surface area loading rate (SALR) of 5.2 ± 0.1 g TAN/m²·d and a hydraulic retention time of 2h showed a successful and stable nitrite accumulation. The average surface area removal rate (SARR) of 2.3 ± 0.2 g TAN/m²·d (theoretical performance objective of 2.7 g TAN/m²·d), TAN removal efficiency of 43.1 ± 3.4% (theoretical performance objective of 53%) and NO₂- / (NO₂- + NO₃-) ratio of 82.4 ± 4.8% (theoretical performance objective of 100%) meets the necessary requirement to support subsequent cost-efficient anammox process. Biofilm analyses of the laboratory-scale, elevated loaded PN MBBR indicated that the attached biofilm was thick and dense, stable biofilm that did not show and biofilm loss or washout. Biofilm cell viability analyses was indicative of an active biofilm. The ratio of AmoA gene targets of the ammonia oxidizing bacteria (AOB) in the MBBR biofilm to the targeted gene region of the Nitrospira nitrite oxidizing bacteria (NOB) population demonstrates that NOB activity suppression of this technology was the dominant mechanism of nitrite-oxidation in the elevated loaded PN MBBR system. In North America, the TAN removal performance of waste stabilization ponds (also termed wastewater treatment lagoon systems), which are widely applied as rural WRRFs, is often not stable due to seasonal temperature variations. Nitrifying MBBR as an upgrade TAN removal unit has been successfully applied to improve TAN removal during winter. However, re-seeding the nitrifying MBBR biofilm during each seasonal operation period is not sustainable. There is therefore an urgent need for optimizing storage strategies of nitrifying MBBR carriers when used as TAN removal upgrade systems of rural WRRFs. The study of storage strategies for nitrifying MBBR as lagoon upgrading systems indicated the batch storage of the nitrifying MBBR biofilms with intermittent aeration could be an effective storage strategy for short-term (12 weeks) storage. Carriers stored in continuous flow aerated condition was shown to be the second most suitable storage method for nitrifying MBBR carriers for systems exposed to less than 12 weeks of storage. Carriers stored in dry condition, batch aerated conditions without flow, and continuous flow aerated condition for long-term (over 18 weeks) failed to achieve full nitrification following 18 days of operation conditions. Carriers stored in dry condition did not successfully achieve full nitrification for short-term and long-term storage and may not be applied to store full nitrification MBBR carriers. The study suggested that, compared to re-seeding start up strategy of the lagoon upgrading nitrifying MBBR biofilm, the use of the appropriate storage strategies, such as batch aerated conditions without flow, has the potential to shorten the start-up time and save energy during the non-discharge periods.

This thesis reports on the research outcome of corrosion mechanism and corrosion rate of mild steel in different environments (saline, alkaline solutions and concrete media) using potentiodynamic polarization technique. The study also included the effect of corrosion on bond strength between reinforcing steel and concrete using pull-out test. Corrosion of mild steel and 316L stainless steel with different surface conditions in 1, 3 and 5% saline (NaCl + Distilled water) was investigated. Specimens ground with 200 and 600 grit silicon carbide grinding paper as well as 1¿m surface finish (polished with 1¿m diamond paste) were tested. In case of mild steel specimens, reduction in surface roughness caused increase in corrosion rate, while in 316L stainless steel corrosion rate decreased as the surface roughness improved. Metallographic examination of corroded specimens confirmed breakdown of passive region due to pitting corrosion. Corrosion of mild steel was also investigated in alkaline solution (saturated calcium hydroxide, pH =12.5) contaminated with 1, 3 and 5% saline. A series of corrosion experiments were also conducted to examine the efficiency of various concentrations of calcium nitrite (CN) on corrosion behaviour of both as-received and polished mild steel in alkaline solution containing 3% saline after 1 hour and 28 days of exposure. Corrosion rate was higher for the as-received than polished mild steel surface under the same testing conditions in NaCl alkaline solution with and without nitrites due to the effect of surface roughness. Morphology investigation of mild steel specimens in alkaline solution ii containing chlorides and nitrites showed localized pits even at nitrite concentration equal to chloride concentration. Corrosion of steel bars embedded in concrete having compressive strengths of 20, 30 and 46MPa was also investigated. The effect of 2 and 4% CN by weight of cement on corrosion behaviour of steel bar in low and high concrete strengths specimens were also studied. All reinforced concrete specimens were immersed in 3% saline solution for three different periods of 1, 7 and 15 days. In order to accelerate the chemical reactions, an external current of 0.4A was applied. Corrosion rate was measured by retrieving electrochemical information from polarization tests. Pull-out tests of reinforced concrete specimens were then conducted to assess the corroded steel/concrete bond characteristics. Experimental results showed that corrosion rate of steel bars and bond strength were dependent on concrete strength, amount of CN and acceleration corrosion period. As concrete strength increased from 20 to 46MPa, corrosion rate of embedded steel decreased. First day of corrosion acceleration showed a slight increase in steel/concrete bond strength, whereas severe corrosion due to 7 and 15 days corrosion acceleration significantly reduced steel/concrete bond strength. Addition of only 2% CN did not give corrosion protection for steel reinforcement in concrete with 20MPa strength at long time of exposure. However, the combination of good quality concrete and addition of CN appear to be a desirable approach to reduce the effect of chloride induced corrosion of steel reinforcement. At less time of exposure, specimens without CN showed higher bond strength in both concrete mixes than those with CN. After 7 days of corrosion acceleration, the higher concentration of CN gave higher bond strength in both concrete mixes. The same trend was observed at 15 days of corrosion acceleration except for the specimen with 20MPa compressive strength and 2% CN which recorded the highest deterioration in bond strength.

No description available.

A number of innovative nitrogen removal technologies have been developed to address the treatment challenges caused by stringent regulations and increasing chemical and energy cost. A major contributing factor to these challenges is the liquid stream originating from the process of dewatering anaerobically digested solids. This liquid, also knows as centrate, reject water or sludge liquor, can cause an increase of up to 25% in ammonia loading. The recently discovered anaerobic ammonia oxidation (anammox) process is a major breakthrough for treatment of these streams as it has the potential to remove up to 85% of nitrogen load without external carbon source addition. The anammox process is combined with another process that oxidizes half of the ammonia to nitrite (nitritation) in a separate reactor such as in the SHARON process, or in the same reactor such as in the DEaMmONification (DEMON) process. Despite intensive laboratory research for the last 10 years to fully understand these processes, there is still a high level of skepticism surrounding the implementation of full-scale systems. The reason for this skepticism could be due to frequent failures observed in the lab scale systems as well as reported slow bacterial growth. We think that this technology might be used more effectively in the future if process kinetics, inhibition and toxicity can be better understood. This work focused on the DEMON process with a goal to understand the kinetics and inhibition of the system as a whole and the anammox process in particular. A DEMON pilot study was undertaken at the Alexandria Sanitation Authority (ASA) and had several study participants, including ASA, the District of Columbia Water and Sewer Authority (DCWASA), CH2M Hill Inc., Envirosim Ltd, the University of Innsbruck and Virginia Tech. We investigated the growth rate of anammox bacteria within a quasi-optimal environment. Laboratory-scale experiments were conducted to assess anaerobic ammonia oxidation inhibition by nitrite as well as aerobic ammonia oxidation inhibition by compounds present in the DEMON reactor feed, such as a defoaming agent, a sludge conditioning polymer, and residual iron from phosphorus removal practices. The study revealed that the DEMON process can be efficiently controlled to limit nitrite accumulation capable of causing process inhibition. The target ammonium loading rate of 0.5 kg/m3/d was reached, and no upset was noticed for a loading up to 0.80 kg/m3/d with an HRT of 1.7 days. The ammonia removal efficiency reached an average of 76% while total nitrogen removal efficiency had an average of 52%. Most of the process upsets were caused by aerobic ammonia oxidation failure rather than anammox inhibition. Failure in ammonia oxidation affected pH control, a variable which is at the center of the DEMON process control logic. The pilot study is summarized in Chapter 3 of this Dissertation. The low anammox maximum specific growth rate (µmax,An) as well as nitrite inhibition are historically reported to be the major process challenges according to the literature, but the degree to which each contributes to process problems differs widely in the literature. In this study, we estimated µmax,An by using the high F:M protocol commonly used for nitrifying populations. We also studied the effect of both short term and sustained nitrite exposure on anammox activity. In this study, µmax,An was estimated to be 0.017 h-1. The study results also suggest that anammox bacteria can tolerate a spike of nitrite-N at concentrations as high as 400 mg/L as long as this concentration is not sustained. Sustained concentrations above 50 mg/L caused a gradual loss of activity over the long term. Finally, the inhibition of aerobic ammonia oxidizing bacteria (AerAOB) observed in the DEMON reactor was investigated using laboratory experiments and is reported in Chapter 6. AerAOB inhibition was, in most cases, the main reason for process upset. Compounds that were suspected to be the cause of the inhibition were tested. The study noticed that a defoaming agent, polymer and ferrous iron had some inhibiting properties at the concentrations tested. / Ph. D.