Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 188-201). Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--University of Tennessee, Knoxville, 2003. / Title from title page screen (viewed Oct. 8, 2003). Thesis advisor: Kevin, G. Robinson. Document formatted into pages (viii, 98 p. : col. ill.). Vita. Includes bibliographical references (p. 73-79).

No description available.

The success of enhanced biological phosphorus removal depends on the constant availability of volatile fatty acids (VFAs). To reduce costs of purchasing external carbon, waste streams would be a preferred source for nutrient removal. VFAs were shown to vary in the incoming sewage and fermentate from primary sludge (PS). Another available source of organic to generate VFAs is waste activated sludge (WAS). The effect of solids retention time and biomass concentration, as well as the effect of temperature and requirement for mixing on generation of VFA from the fermentation of WAS were investigated. It was found that VFA yields from sludge fermentation increased with SRT. At the longest SRT of 10 days improved biomass degradation resulted in the highest soluble to total COD ratio and the highest VFA yield. WAS fermentation was found highly temperature-dependent. The overall VFA–COD concentration in the non-mixed reactors was much lower than the mixed reactors. The study of fermentation of PS, WAS and a mixture of WAS and PS demonstrated that PS fermentation predictably generated a significantly higher amount of soluble COD than WAS. Co-fermentation of WAS with PS enhanced soluble COD production and increased the release of phosphate and ammonium. Fermentation of combined PS and WAS sludge generated a concentration of phosphate high enough to allow phosphorus recovery as struvite The effect of using glycerol as an external carbon source in biological phosphorus removal was investigated. Using glycerol directly resulted in the failure of the process which maintained enhanced biological phosphorus removal. When glycerol was co-fermented with waste activated sludge, significant VFA production was observed. By 2 | P a g e supplying the system with the VFA-enriched supernatant of the fermentate, biological phosphorus removal was enhanced. It was concluded that, if glycerol was to be used as external carbon source for biological phosphorous removal, the effective approach was to ferment glycerol with waste activated sludge. According to the cost analysis, the economic benefit of WAS fermentation can be demonstrated in three ways: 1) cost saving in external carbon addition; 2) cost saving in sludge handling; 3) revenue from phosphorus. At current condition, the value of the recovered P product is insignificant relative to the cost of chemicals that required for recovery and capital cost of the facilities. However, P recovery becomes important when the sustainability take into account.

No description available.

This Technology in Industry Fellowship (TIF) funded Masters Project was structured around Computational Fluid Dynamics (CFD) modelling for Lemar Environmental Ltd (Lemar). This study is a component of a larger programme that is being undertaken by Lemar concerning the vitrification process. The modelling has built on an initial model developed by CSIRO for Lemar and has been carried out under the direction of Canterbury University. The modelling involved computer simulations and detailed comparisons of the gas flow for both high and low swirl vanes, in both the steady state and transient modes. The output of this activity; velocity profiles (tangential and axial), vorticity, as well as particle tracking (in steady state mode only) were compared to literature and evaluated for both scenarios. As the study was restricted to the gas flow in transient mode, no recommendations and extrapolated modifications to the burner geometry and plant equipment can be made as they have to be verified by the particle motion within the gas flow. The steady state particle simulations obtained through this project, did not provide sufficient evidence to conclude that particles attach to the outer wall and only demonstrated the influences that the high and low swirl had on the particles. Further investigations of transient particle tracking would provide an overall interpretation as to whether or not the dried sludge particles bounced or stuck to the viscous slag layer and a commentary as to their movement in the chamber. Lemar's strategic vitrification programme is still active and the resulting redesign process is nearing completion and modifications to the plant are expected to be finalised by January 2008. Following extensive testing by Lemar it is understood that they would be looking to seek venture capital in order to progress the project to the market. In order for the final stage of the sewage sludge vitrification plant project to commence, Lemar has been in consultation with subject matter experts in the field, as well as undertaking trials on the plant, computer modelling and research into both the technical and international marketing prospects for the combustion technology. The detailed analysis and research undertaken through the CFD modelling conducted for this Project, recommends that Lemar conducts further CFD modelling to investigate transient particle tracking before any plant or geometry modifications are proposed and undertaken in order to optimise the ash capture which is a key output of the vitrification process.

Sludge disposal is a worldwide problem due to increasing volumes and respective environmental regulations. Currently the most common ways to dispose sludge are agricultural use, disposal in landfills, incineration and sea dumping. By drying sludge volumes can be decreased and the respective heating value increased. Sludge mainly originates from wastewater treatment. The Swedish pulp and paper mills produce approximately 400 000 - 500 000 metric tons of dry sludge each year. This includes roughly 60 000 metric tons of dry biosludge which mainly consists of bacteria and is difficult to dry due to high amounts of intercellular water. New drying methods for biosludge are hence needed. The purpose of this project is to investigate the possibility to dry biosludge in a high-velocity cyclone dryer since the technology has been shown to be able to handle sticky materials. The sludge used in this project originates from the biological wastewater treatment at the pulp and paper mill Metsä Board Husum, located in Husum, Sweden. The achieved dry matter contents and the specific energy consumption have been examined and compared with established drying methods.  Design of experiments has been used during the trials for optimizing the information attained from a limited number of trials including effects of inlet air temperature, sludge feeding rate and recycling of drying air. The respective factors were varied in three steps and relevant temperature, pressure, humidity, flow and material mass values were measured for analysing the process.  Models for attained dry matter content, specific energy consumption (total and of the fan), removed water and fan power were developed and had high statistical significance. The models showed that sludge dry matter content up to 80% could be achieved. The total specific energy consumption was over 1.6 kWh/kg H2O, which is higher than for established drying methods, but the specific energy consumption of the fan was as low as 0.7 kWh/kg H2O. The specific energy consumption of the fan was used to approximate dryer operation with excess heat during which it could compete with all established drying methods. A case where the excess heat available at Metsä Board Husum would be used to dry generated biosludge was investigated and supported a need for a priority order between maximizing sludge dry matter content and minimizing specific energy consumption of sludge drying. If sludge dry matter content is prioritised alternative drying methods may prove more suitable. To attain a better understanding of the high-velocity cyclone dryer and drying of biosludge the evaporation energy of sludge at different dry matter contents, the effects of various sludge inflow temperatures and the effect of fan rotation speed should be included future investigations. / Bortskaffande av slam har blivit ett världstäckande problem på grund av stora volymer och miljöreglering. De vanligaste sätten att bortskaffa slam är genom markanvändning, deponering, förbränning och dumpning i haven. Genom att torka slammet minskar volymen och värmevärdet ökar. Slammet har sitt ursprung i vattenrenings processer och svenska pappers- och pappersmassabruk producerar ungefär 400 000 – 500 000 ton slam per år i torrvikt. Av dessa är ungefär 60 000 ton biologiskt slam som till största del består av bakterier och är svårtorkat på grund av den höga andelen intercellulärt vatten. För att torka biologiskt slam behövs nya torkmetoder och syftet med detta projekt vara att undersöka möjligheten att torka biologiskt slam i en cyklontork då cyklontorken kan hantera kladdiga material. Slammet som använts under projektet kommer från pappersbruket Metsä Board Husum. Torrhalten som kunde uppnås och den specifika energin har undersökt och jämförts med etablerade torkmetoder. Design of experiments användes för att optimera informationen som går att få ut från ett begränsat antal försök och påverkan av inluftstemperaturen, matningshastigheten av slammet och positionen av spjället i luftåtervinningssystemet har undersökts. Faktorerna varierades i tre steg och temperaturer, tryck, luftfuktigheter, flöden och vikter har mätts för att analysera processen.  Modeller för torrhalten, den specifika energin (totalt och för fläkten), avdrivet vatten och fläkteffekten har beräknats med hög statistisk signifikans. Modellerna visar att upp till 80 % torrhalt kan nås. Den totala specifika energin ligger över 1.6 kWh/kg H2O vilket är högre än den specifika energin för etablerade torkmetoder men den specifika energin för fläkten kan understiga 0.7 kWh/kg H2O. Den specifika energin för fläkten kan approximera att torken körs med överskottsvärme och det är fallet kan cyklontorken konkurer med de etablerade torkmetoderna. Möjligheten att använda sig av överskottsvärmen på pappersbruket Metsä Board Husum för att torka deras biologiska slam har undersökts och en prioritering mellan hög torrhalt och låg specifik energi kommer behöva göras. Om hög torrhalt prioriteras kan andra torkmetoder vara att föredra. För att öka förståelsen för cyklontorken och torkning av biologiskt slam kan förångningsenergin för slammet vid olika torrhalter, effekten på torkresultaten från olika temperaturer på slammet in i cyklonen och effekten av olika effekter på fläkten undersökas.

The success of enhanced biological phosphorus removal depends on the constant availability of volatile fatty acids (VFAs). To reduce costs of purchasing external carbon, waste streams would be a preferred source for nutrient removal. VFAs were shown to vary in the incoming sewage and fermentate from primary sludge (PS). Another available source of organic to generate VFAs is waste activated sludge (WAS). The effect of solids retention time and biomass concentration, as well as the effect of temperature and requirement for mixing on generation of VFA from the fermentation of WAS were investigated. It was found that VFA yields from sludge fermentation increased with SRT. At the longest SRT of 10 days improved biomass degradation resulted in the highest soluble to total COD ratio and the highest VFA yield. WAS fermentation was found highly temperature-dependent. The overall VFA–COD concentration in the non-mixed reactors was much lower than the mixed reactors. The study of fermentation of PS, WAS and a mixture of WAS and PS demonstrated that PS fermentation predictably generated a significantly higher amount of soluble COD than WAS. Co-fermentation of WAS with PS enhanced soluble COD production and increased the release of phosphate and ammonium. Fermentation of combined PS and WAS sludge generated a concentration of phosphate high enough to allow phosphorus recovery as struvite The effect of using glycerol as an external carbon source in biological phosphorus removal was investigated. Using glycerol directly resulted in the failure of the process which maintained enhanced biological phosphorus removal. When glycerol was co-fermented with waste activated sludge, significant VFA production was observed. By 2 | P a g e supplying the system with the VFA-enriched supernatant of the fermentate, biological phosphorus removal was enhanced. It was concluded that, if glycerol was to be used as external carbon source for biological phosphorous removal, the effective approach was to ferment glycerol with waste activated sludge. According to the cost analysis, the economic benefit of WAS fermentation can be demonstrated in three ways: 1) cost saving in external carbon addition; 2) cost saving in sludge handling; 3) revenue from phosphorus. At current condition, the value of the recovered P product is insignificant relative to the cost of chemicals that required for recovery and capital cost of the facilities. However, P recovery becomes important when the sustainability take into account.

No description available.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 110-122). Also available in electronic version.