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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Radioisotopes in Domestic Wastewater and Their Fate in Wastewater Treatment

Pan, Xiaodi 08 September 2016 (has links)
"Modern medical therapies involving radioisotopes provide radionuclide contamination in wastewater. These radioisotopes present in wastewater increase the possibility of human exposure to radiation. The objective of this work was to study the fate of radionuclides of medical sources in wastewater, and to determine the distribution of various radionuclides in different stages of wastewater treatment. Influent, return activated sludge and effluent samples were collected from four wastewater facilities in Massachusetts. Samples were collected approximately twice a month over 4 months. The radionuclides and their decay products were tested by inductively coupled plasma with mass spectrometry (ICP-MS) and broad energy germanium detector analysis (BEGe). The samples were analyzed to determine the content and radioactivity of each target radionuclide and decay product for three treatment stages (influent, return activated sludge and effluent) from each facility at different sampling times. The results indicated that I-131 is the only radionuclide in wastewater, however many decay products were identified. Recommendations are put forward according to the testing results."
42

Optimization of Moving Bed Biofilm Reactor (MBBR) Operation for Brewery Wastewater Treatment

Boyle, Kellie 06 May 2019 (has links)
The significant rise in the number of micro-breweries in North America has increased the need for efficient on-site industrial wastewater facilities. Brewery wastewater is considered to be a high strength food industry wastewater with high variability in terms of both organic and hydraulic loading. Small breweries require cost-effective, reliable, and simple to operate treatment technologies to properly manage their brewery wastewaters. Moving bed biofilm reactor (MBBR) technology has shown promise at the lab-scale and full-scale with respect to brewery effluent treatment. MBBR systems have the capability for short hydraulic retention times (HRT), high organic loading rates, as well as increased treatment capacity and stability due to biofilm retention, all within a compact reactor size when compared to other aerobic and attached growth treatment options. Two MBBR systems utilizing two different carrier types (Kaldnes K5 and Kontakt), and a suspended growth (SG) control reactor, were used in this study to investigate the impacts of surface area loading rate (SALR) and HRT on attached growth (AG) and SG kinetics and carrier type for brewery wastewater at 2000 mg-sCOD/L. An increase in SALR from 10-55 g-sCOD/m2/d while at an HRT of 12 hr resulted in no significant impact in total volumetric removal rates between the MBBR systems and the SG control reactor; however, MLSS concentrations were lower for the MBBR systems at SALRs below 55 g-sCOD/m2/d, which indicated AG contribution. Over 92% soluble chemical oxygen demand (sCOD) removal was achieved at each SALR in each of the three reactors. These results indicated that the reactors were substrate limited and SG controlled. Due to the SG dependency, the difference between the two types of carriers was indeterminate. A decrease in HRT from 12-3 hr while maintaining an SALR of 40 g-sCOD/m2/d resulted in a shift from SG to AG dependency in the MBBR systems. The total volumetric removal rates for the MBBR systems were significantly higher at HRTs of 3 and 4 hr as compared to the SG control reactor. The AG volumetric removal rates from both MBBR systems were highest at an HRT of 3 and 4 hr. At an HRT of 12 hr all three reactors maintained over 92% sCOD removal; however, at an HRT of 4 hr the SG control reactor dropped to 88% and at 3 hr to 61%, whereas the MBBR systems maintained 95% removal at an HRT of 4 hr and only decreased to 73% at 3 hr. These results indicated that the MBBR systems were more effective at lower HRT than the SG control reactor, with no significant difference observed between the two carrier types tested. Biofilm morphology and viability from each of the two carriers utilized in the study of moving bed biofilm reactor (MBBR) treatment of brewery wastewater were investigated using stereoscopy and confocal laser scanning microscopy (CLSM) in combination with live/dead cell staining. Both carriers demonstrated thicker and more viable biofilms at high SALR and denser and less viable biofilms at low SALR. At lower HRT, the carriers reacted differently resulting in thicker, but less dense biofilms on the Kontakt carriers and thinner, but more dense biofilms on the K5 carriers. However, no trend in cell viability was observed with change in HRT. Although the systems were suspended growth (SG) dominated, based on the MBBR kinetics and carrier biofilm morphology and cell viability, either carrier would be a viable choice for an MBBR treating brewery wastewater at HRTs between 4 to 12 hr and SALRs between 10-55 g-sCOD/m2/d.
43

Hybrid system for wastewater treatment in multifunctional wetlands - A case study at UNIVATES in Lajeado, RS, Brazil

Bengtsson, Erica, Hjertstrand, Sannam January 2008 (has links)
<p>Abstract</p><p>Centro Universitaire UNIVATES is located in the town Lajeado that is situated in the most southerly state, Rio Grande Do Sul, in Brazil. The university has 5000 students, teachers and others staff. UNIVATES is not satisfied with their present wastewater situation and wants to improve it by eliminate the smell caused by the wastewater. They would also like to remove the oil that the storm water brings into the wetland. The high amount of particles in the storm water gives rise to a lot of sediments that eventually will fill up the wetland, and something has to be done about this, if the wetland should continue to be in use. Another aspect to consider is the wish of some people at UNIVATES, for the wetland to be a beautiful and recreational place. All these factors had to be considered, which led to the main question: How can the use of the wetland for wastewater treatment be combined with the request for the wetland to be a beautiful place with the wildlife preserved? </p><p>During the course Wetland Technology that we took before our departure to Brazil, we got introduced to the situation at UNIVATES by Professor André Jasper and Odorico Konrad who visited the course several times. They pointed out that the main issue is the smell from the wastewater and later during the field study at UNIVATES, more information were obtained through discussions, meetings and conversations with the people involved. Several visual inspections were carried out by walking around the wetland. We could determine where and how the inlets and outlets to the wetland were and when it was clear which inlets that brought wastewater and which that brought storm water, the water flow of the wastewater was estimated. Water samples from the wetland were collected at five different sites and analyses of pH, BOD, COD, N-Tot, phosphorus and metals were done by the accredited laboratory at UNIVATES. To test some of our theories, we did a smaller practical experiment that got the name Superficial Filtration Bed. </p><p>The results from the water samples showed the highest BOD, COD, N-Tot and Phosphorus levels in the samples from site 2 and 4 and this reveals that it is wastewater. This was also confirmed by the smell that we felt at these sites during the visual inspections. The results also showed that there is no wastewater coming from site 1, 3 and 5. </p><p>Our final proposal is to create a multifunctional wetland with the purpose to take care of both storm water and wastewater and at the same time work as a research and recreational area. The wetland, which would be divided into two parts, will constitute of all the fundamental functions; storm water buffering, sedimentation basin and biological oil separation and treatment. There will also be research sites and hybrid system for wastewater treatment. The hybrid system will consist of two steps where the first is aerobic and the second both aerobic and anaerobic. The first step is a Superficial Filtration Bed (SFB) and the second a FWS wetland. </p><p>The conclusion of this thesis is that more detailed research is needed to be able to dimension the specific functions correctly. With some further investigations the proposal presented is possible to carry through and our feeling when we left UNIVATES was that the people responsible really liked our ideas. They made it clear that they want to make a change and improve the situation and with the help they have gotten from us, they are a few steps closer to solving the problem.</p>
44

Land treatment system design with system parameter optimization support model

Hagimoto, Yutaka 30 April 2004 (has links)
Increasing costs for wastewater treatment provide incentives to evaluate system alternatives, especially among small communities with limited financial resources. Land treatment systems with hybrid poplar tree plantations are becoming increasingly popular as one such alternative in the Pacific Northwest. Land treatment systems are made up of a complex dual system: the wastewater treatment system and the poplar tree plantation. The complex dual system must account for temporal and spatial variability of natural systems. The goal of the system design is to optimize system parameters, after accounting for system complexity and variability, to maximize economic return without causing adverse effects on the environment and society. This study presents a system optimization model which accounts for the system complexity and natural variability. The model consists of three submodels: nitrogen loading rate estimation submodel, nitrate leaching submodel and total net revenue estimation submodel. The composite model identifies the maximum total net revenue and determines associated system design parameters. An optimization example for a hypothetical community with a population of 5,000 is presented. The optimal system with no time horizon or land area constraints is expected to return a net revenue of $773,659 over a 296-year project lifetime. The wastewater treatment system is characterized by the optimal nitrogen loading rate of 49 kgN/ha and the corresponding estimated leachate nitrate concentration of 8.80 mgN/L. The poplar tree plantation is characterized by the optimal rotation period of 8 years and the optimal total field size of 202 ha. Additional analysis indicates that total net revenue would not be positive if the design system lifetime was shorter than 60 years, or the maximum field size was smaller than 150 ha. Accounting for land depreciation due to wastewater application reduced the optimal nitrogen loading rate by 2 kgN/ha. Costs for an equity loan would reduce system profitability significantly. Sensitivity analysis demonstrated that the model was sensitive to nitrate leaching and poplar tree growth parameters. It was concluded that calibration for site specific nitrate leaching and poplar hybrid specific growth parameters should be evaluated to have more confidence in model performance. / Graduation date: 2004
45

Performance on the Constructed Wetlands for Clarification of Sewage Mixed with Secondary-treated Swine Wastewater

Cheng, Li-lin 18 July 2010 (has links)
The Wu-Luo River, located in the Ping-Tong County of southern Taiwan, has long been polluted by untreated domestic and partially treated swine wastewaters and is among the most polluted rivers in Taiwan. The main objective of this study was to find a practical and effective way to improve water qualities of seriously polluted rivers with a natural technology. The Wu-Luo River was taken as an illustration of the approach in the first subject of this study. The second subject used mixed sewage and a partially-treated swine waster as a simulated polluted river water to test if an UASB (upflow anaerobic sludge blanket) reactor followed by a constructed wetland (CW) system could be used for clarification of the water. For verification of the performance results achieved by the second subject, the third subject used a pilot UASB-CWs system to test the performances by using the water sampled from the Wu-Luo River. A full-scale constructed wetland system (CWs) has been in operation for cleaning a portion of polluted Wu-Luo River water since January 2005. The first section of study investigated the efficiency and treatment capacity of this full-scale CWs on the river shore, and the operation parameters of CWs could be improved to enhance the treatment. Due to the limited efficiency and capacity of the full-scale CWs treatment, the second section of this study use a pilot-scale system to treat wastewater mixed in laboratory to simulate the polluted water treatment of the Wu-Luo River. This system was equipped with an UASB reactor in front of the CWs, which is expected to raise the efficiency and capacity of the CWs. Since the system of UASB-CWs in the second section showed good performance, the actual Wu-Luo River water was introduced to 2 pilot-scale systems which only the experimental one had UASB reactor before CWs in the third section of study. The removal efficiency of pollutants including heavy metals between the experimental and control systems was compared. In the first section, the Wu-Luo River CWs occupied a total area of 18 hectares in which approximately 9 hectares were wetted by the introduced river water. Close to 4.7 hectares of the CWs was flooded by the river water with 1.9 hectares occupied by emergent and floating plants. A total water volume of about 9,930 m3 was estimated. During the investigation period, 10,000-20,000 m3/d (CMD) (average 10,800 CMD) of the polluted river water was introduced to the CWs with a hydraulic retention time (HRT) of 0.92 day. It was concluded that water sampled from near the midpoint of the CWs got better clarification results than those from the effluent end. Pollutant removal efficiencies were 60, 60, and 67%, respectively, for TCOD, BOD, and SS at the midpoint, and 56, 54, and 45%, respectively, for TCOD, BOD, and SS at the effluent end. Organics, N, and P released from decayed plants were responsible for the poor water qualities at the end. The CWs had only a TN removal efficacy of approximately 18% with no TP removal effect. In the second section, a pilot system with an UASB reactor combined with two CW reactors was used to evaluate the feasibility of treating wastewater samples (mixture of sewage and partially-treated swine wastewater). To observe the influence of HRT on the removal efficiency of various pollutants in the wastewater in the UASB reactor, 2 phases of experiments with HRTs of 6 and 2 hours were conducted. The UASB reactor responded well in removing most of the pollutants observed except for AN and TP. The average removal efficiency could reach the levels of 93, 91, 86, 89, and 78% for SS, SCOD, SBOD, AN, and TP with the UASB-CWs systems, which have potentials to be used to improve the water quality in river in practice. To observe the influence of HRT on the removal efficiency of various pollutants in the wastewater in the UASB reactor, 2 phases of experiments with HRTs of 6 and 2 hours were conducted. In the third section, the experimental system was composed of UASB-CW1-CW2 in seris, whereas that of control system was only CW1-CW2 in series. Water samples were taken from Wu-Luo River water. To observe the influence of HRT on the removal efficiency of various pollutants in the river water in the UASB reactor, 3 phases of experiments with HRTs of 6, 4, and 2 hours were conducted. Heavy metals were easily settled in the first section of treatment, the concentrations of them were found higher in the sediments in UASB of experimental system than those in CW1 of control system. UASB can be used for primary sedimentation to prevent the CW1 blocking especially when the river quality changes dramatically on SS. With 4 hrs of HRT in UASB and 32 hrs in CW1 and CW2 each, the removal efficiency is the highest for all pollutants observed in this study. In the effluent of both of the whole systems, more than 96% of SS, NH3, and TN were removed, while more than 70% of COD and TP, more than 60% of BOD were also removed. When HRT in CW1 and CW2 is decreased to be lower than 16 hrs, the ability of CWs to remove TN and TP is also lowered.
46

Development of an electron beam irradiation design for use in the treatment of municipal biosolids and wastewater effluent

Lazarine, Alexis Dawn 15 May 2009 (has links)
The need for pathogen-free water supplies has spurred investigations into the use of ionizing radiation for the treatment of wastewater effluent and municipal biosolids. The objective of this research was to develop an electron-beam irradiation scenario to effectively eliminate microbial pathogens from municipal biosolids and wastewater effluent. The Monte Carlo N-Particle (MCNP5) radiation transport code was used to simulate the irradiation scenario. Using MCNP5, dual electron-beam sources were modeled as planar surface sources above and below a stainless steel delivery trough containing either effluent water or one of two biosolids material compositions. A dose deposition analysis was performed to assess both the planar dose distribution and 25 depth-dose curves. In addition, a density perturbation study was performed to assess the variance in the dose deposition for different mass solids concentrations. To validate the MCNP5 code for this type of application, a benchmark study was performed. Two municipal biosolids materials and water were irradiated in plastic bags on a conveyor belt using a 10-MeV electron accelerator with the exit window below the material. The experimental configuration was modeled with the MCNP5 radiation transport code. Simplified and detailed models were created and analyzed. Lastly, an economic analysis was performed to assess whether this treatment method is a financially viable alternative to current wastewater treatment methods. Processing capacity was calculated for two accelerator specifications. These capacity rates in conjunction with the operating and capital costs per dry ton to irradiate the material were compared with existing data for electron beam processing of municipal biosolids. The cost breakdown was also compared with quoted costs for existing conventional methods. The models developed showed that the use of 10MeV electron-beam technology for the treatment of wastewater effluent and municipal biosolids is effective and economically feasible. The benchmarking study illustrated the accuracy of Monte Carlo simulation for this type of application. The method development process was shown to be adaptable for various material compositions and irradiation configurations.
47

Escherichia coli Regrowth and Macroinvertebrate Health in Urban and Rural Streams

McCrary, Kathryn Jordan 2011 May 1900 (has links)
Over the last few decades, increased urbanization has led to a new recognition in stream health – the urban stream or the urban stream syndrome. Understanding urban water quality is important for identifying those factors or sources that contribute to impairment. Many streams are listed as impaired because of the increased concentrations of pathogens. While wastewater treatment plants (WWTPs) discharge effluent that has been disinfected, often downstream from WWTPs point sources are high numbers of indicator bacteria, Escherichia coli. This study collected data on the recovery and regrowth of E. coli by collecting ultraviolet light treated effluent from the Carters Creek WWTP and spiked it with three different concentrations of DOC derived from a leaf and grass extract. Escherichia coli were enumerated at 6, 12, 18, 24, 36, 48, and 72 hours. After 6 h growth for each of the grass treatments, except for the control and high grass treatment exceeded the primary contact recreation standard for surface water quality. At 18h the low and high leaf treatments exceeded the primary contact recreation standard for surface water quality. The chemistry of each flask was analyzed for DOC, total N, NO3-N, NH4-N, Na , K , Mg 2, Ca 2, F-, Cl-, SO4-2 and PO4-3 at t=0 and t=72 h. CNP values for both leaf and grass treatments ranged from 2.22 - 36.5. Regrowth was not observed in those treatments with a CNP value below 5. Biodegradability of the treatments was examined to identify the limiting nutrient. By focusing on reducing the CNP value below 5 of the receiving water, recovery and regrowth of E. coli downstream from WWTPs can be reduced. The biodegradability test suggested that in the presence of excess DOC, N is the limiting nutrient. Certain macroinvertebrate species, Ephermeroptera, Trichoptera, and Plecoptera (EPT), are indicators of good stream health. Macroinvertebrates were collected at nine watersheds within the Bryan/College Station area, a rapidly urbanizing community, upstream and downstream from WWTPs and analyzed for relative abundance of pollution intolerant (percent EPT) and pollution tolerant species. All sites downstream from a WWTP had percent EPT present in the collection.
48

Treatment of Chemical Mechanical Polishing Wastewater by a Simultaneous Electrocoagulation/Electrofiltration Process

Chen, Fu-Cheng 10 February 2004 (has links)
In this work, a novel treatment module capable of simultaneously enacting electrocoagulation and electrofiltration was designed, fabricated, and tested aiming for the reclamation of CMP (chemical mechanical polishing) wastewater. In general, CMP wastewater contains sub-micron particles and has high alkalinity, turbidity, total solids content, and silica content. Discharge of CMP wastewater without proper treatment would pose a great threat to the environment and ecology. In this investigation, oxide CMP wastewater and mixed CMP wastewater were obtained from a wafer fab in Taiwan. They were characterized by various standard methods. In this study, the efficiency of this dual-function treatment module (using aluminum as the sacrificing anode and stainless steel as the cathode) was evaluated in terms of applied electric field strength (0 ~ 112.5 V/cm), influent velocity (112 ~136 cm/s), and transmembrane pressure (1.0 ~ 3.0 kgf/cm2) on permeate qualities. Experimental results have shown that the contents of total solids of permeates could be reduced to about 180 mg/L and 426 mg/L, respectively for oxide CMP wastewater and mixed CMP wastewater. The respective values of turbidity and total organic carbon could also be reduced to below 1 NTU and 1.5 mg/L. Therefore, the treated water could be reused as the feed water for the ultrapure water production system. In this study, an empirical equation was established to relate the quantity of filtrate and applied electric field strength when CMP wastewater was subjected to electrofiltration alone. It was found that the theoretical aluminum concentration released to the reaction chamber was much greater than the actual one. This would explain why the efficiency of electrocoagulation needs to be improved in this treatment module. Experimental results also have indicated that proper backflushing would be beneficial to the flux of permeate and saving of membrane cost.
49

Application of Constructed Wetland System for Domestic Wastewater Treatment

-yi, Chia 30 August 2006 (has links)
Constructed wetland system is a natural purifying procedure of management and disposal of water and wastewater by means of Ecological Engineering Technology. Neither additional chemical agent nor mechanical equipments and electrical power are needed in the procedure of water quality purifying. It is also a potential Ecological Engineering Technology with advantages of low-cost, easy operation and management, and easy construction. However, the limitation of this technology is the requirement of larger land space for wetland construction. Taiwan features in a subtropical climate, moderate water temperature, abundant sunlight, so its environmental condition is a good fit for constructed wetland technology, which has been verified by numerous pilot and field scales studies in recent years. Due to the necessity of large land space, it is impossible to apply it in the urban environment that is densely populated. In the rural area of Taiwan, however, with the industry development or industry moving outside, there appears a lot of fallow lands, idle lying factories. Moreover, the undeveloped construction of sewage work in Taiwan (especially in rural areas) results from inadequate construction expenditure supported by government, while discharge raw sewage in urban causes water pollution and water shortage. Hence, if we could establish constructed wetlands in the programmed proper places (such as presumptive address in parks or low-rent fallow lands), less construction expenditure could be used to construct sewage work and to protect water resource. After the proper programming and management, constructed wetland has multiple functions such as sightseeing, recreation, and ecology education. In order to explore the possibility of domestic wastewater disposal by constructed wetlands, the research adopted three ecological engineering treatment systems: Erhang constructed wetland system, Gangwei constructed wetland system, and Dajia soil filtration system. In this study, the treatment efficiencies and effectiveness of water quality improvement via these three systems were investigated. Results from the monitoring results of the influents and effluents of these systems were evaluated. In the Erhang constructed wetland, results were collected from July 2004 to October 2005. During this investigation period, the average flow rate was 52 CMD, and the observed biochemical oxygen demand (BOD) removal efficiency and removal rate were 72¡Ó22¢H and 1.68¡Ó1.12 kg/day, respectively. In the Gangwei constructed wetland, results were collected from July 2004 to May 2006. During this investigation period, the average flow rate was 61.6 CMD, and the observed BOD removal efficiency and removal rate were 33¡Ó40¢H and 0.14¡Ó0.19 kg/day, respectively. In the Dajia constructed wetland, results were collected from July 2004 to May 2006. During this investigation period, the average flow rate was 21.92 CMD, and the observed BOD removal efficiency and removal rate were 79¡Ó16¢H and 0.9¡Ó0.5 kg/day, respectively. Results from this study indicate that the three systems could effectively remove the main pollutants in inflow water and the treated water is able to meet the discharged standards. Thus, the constructed wetland scheme has the potential to be developed into an environmentally and economically acceptable domestic wastewater treatment technology. Results from this study will be useful to assist environmental professionals in designing a scale-up system for future application.
50

Removal of algae from facultative pond effluent

Miqdadi, Issam Mahmoud Ahmad January 1992 (has links)
Wastewater stabilization ponds have gained popularity as a means of secondary wastewater treatment because of their low cost and simplicity of operation and maintenance, in addition to several other advantages. However, the presence of algae in the effluent from facultative ponds may cause undesirable environmental impacts, such as DO depletion or eutrophication, in water bodies to which this effluent is discharged. Thus, regulations and/or the adverse environmental impacts of effluents containing algae sometimes necessitate reduction or removal of algae from pond effluents. Many methods have been used for the purpose of removal of algae from wastewater stabilization pond effluent. Upflow rock filtration and coagulationsedimentation have been investigated in this research. In the past, mechanisms of removal of algae in rock filters and factors that affect the removal process have not been well explained. Design of these filters has not been related mathematically to the operating variables. Three pilot rock filters were built for the purpose of this research. The first filter was filled with rock of 1 cm average diameter, the second and third filters were filled with 5 cm and 10 cm average diameter rock, respectively. Five different hydraulic loadings were applied to these filters, with variable influent characteristics and under different environmental conditions. The results of this research have shown that gravitational settling and hydrodynamic forces are the most important mechanisms affecting removal of algae in upflow rock filters. Also, a method of design of unisize-media upflow rock filters for removal of algae from facultative pond effluent has been established. The cost of coagulant has been the main disadvantage of the process of coagulation-sedimentation for algae removal from wastewater stabilization pond effluent. In this research, jar tests were carried out to determine the effect of settling time and/or addition of kaolinite or bentonite with the primary coagulant, alum, on the optimum dose of this primary coagulant required for removal of algae from facultative pond effluent. Both increase in settling time and coagulant aids, namely kaolinite and bentonite, have reduced optimum alum dose. Kaolinite and bentonite, applied as low-cost primary coagulants, were also effective in removing algae from facultative pond effluent. From the very limited experiments carried out at the end of this research, it was shown that crossflow microfiltration has some potential as a process for algae removal from facultative pond effluent. A mathematical model has been developed in this work to describe the eutrophic state of King Talal Reservoir in Jordan. The model predicts that even elimination of phosphorus from the effluent of Al-Samra Wastewater Stabilization Ponds will not bring the reservoir into an oligotrophic state.

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