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(1 - 4 of 4)
- Title
- DEWATERING OF BIOSOLIDS BY SODIUM FERRATE.
- Creator
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Rios, Andrea, Reinhart, Debra, University of Central Florida
- Abstract / Description
-
This study was conducted to evaluate the effectiveness of the liquid form of ferrate for dewatering of biosolids from wastewater treatment facilities. Two different ferrate products prepared using calcium hypochlorite and sodium hypochlorite were used. Samples of anaerobic digested sludge and waste activated sludge with solids content of 2.1% and 0.95 %, respectively were conditioned with both products to evaluate and compare their effectiveness. Centrifugation and filtration of the sludge...
Show moreThis study was conducted to evaluate the effectiveness of the liquid form of ferrate for dewatering of biosolids from wastewater treatment facilities. Two different ferrate products prepared using calcium hypochlorite and sodium hypochlorite were used. Samples of anaerobic digested sludge and waste activated sludge with solids content of 2.1% and 0.95 %, respectively were conditioned with both products to evaluate and compare their effectiveness. Centrifugation and filtration of the sludge after conditioning were used. For centrifugation the volume reduction and the turbidity of the supernatant after centrifugation were evaluated. For filtration, the Capillary Suction Time test was used. The optimum doses and conditions for dewatering of the sludge using ferrate were determined for each type of sludge. The centrifugation and filtration results were compared with those obtained for polymer doses currently used at the wastewater treatment plants where the samples were collected and with ferric coagulants as well. The results of this research indicated that optimum pH was 7.0. The time required to achieve mechanical equilibrium defined as the time at which the volume occupied by the solids was no more than one percent of the preceding reading was 1800 seconds for both types of sludge. The optimum rotational speeds were 800 and 2400 for waste activated sludge and anaerobic digested sludge, respectively. The optimum ferrate dose for anaerobic digested sludge for centrifugation and filtration was 5000 mg/l. For waste activated sludge a dose of 10 mg/l was found to be effective for filtration and centrifugation. The results indicated that the ferrate product prepared using calcium hypochlorite provides better results for the waste activated sludge than the ferrate prepared using sodium hypochlorite, while for anaerobic digested sludge no significant difference was observed. Finally, the results show that ferrate is a cost-effective alternative for the conditioning and disinfection of waste activated sludge, but not for the conditioning of anaerobic digested sludge.
Show less - Date Issued
- 2004
- Identifier
- CFE0000276, ucf:46235
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000276
- Title
- VARIATION OF GEOTECHNICAL STRENGTH PROPERTIES WITH AGE OF LANDFILLS ACCEPTING BIOSOLIDS.
- Creator
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Pinapati, Kishore, Chopra, Manoj, University of Central Florida
- Abstract / Description
-
The solid portion of waste disposal, known as Municipal Solid Waste (MSW) can be landfilled. Landfilling has proved to be a safe, sanitary and economical method of disposal. A by-product from wastewater treatment plants called biosolids is sometimes co-disposed along with MSW in landfills. Recent work at the University of Central Florida has focused on the behavior of the mixture of MSW and biosolids. As an increased amount of waste accumulates in these landfills, it creates a new problem &...
Show moreThe solid portion of waste disposal, known as Municipal Solid Waste (MSW) can be landfilled. Landfilling has proved to be a safe, sanitary and economical method of disposal. A by-product from wastewater treatment plants called biosolids is sometimes co-disposed along with MSW in landfills. Recent work at the University of Central Florida has focused on the behavior of the mixture of MSW and biosolids. As an increased amount of waste accumulates in these landfills, it creates a new problem – the geotechnical stability of landfills. In current literature, classical geotechnical testing methods have been followed to find the strength properties of these landfill materials. Furthermore, geotechnical methods of slope stability analyses have been employed to determine the stability of landfill slopes. As these materials have a high organic content, their strength properties may potentially change with time because of the decay of the organic materials. In the present work, an attempt is made to monitor the change in the geotechnical strength properties of the landfill materials as a function of time. Direct shear tests used for soil testing, with some modifications, were performed on cured compost samples of MSW mixed with biosolids. Geotechnical strength properties of these cured samples were compared to those of an artificially prepared mixture of MSW and biosolids, from the published literature. In addition, direct shear tests are also performed to find the interface properties of a geonet with the cured samples to check the role of a geonet in reinforcing the landfill slopes. A slope stability analysis software SLOPE/W is used to analyze the stability of the landfills. Cohesion is observed to decrease with time while the friction angle increases with time. Stability (the factor of safety against failure) of landfill slopes increases with time due to increased effective stresses and increased friction angle, as the organic material decays. This may result in additional subsidence but an increase in the effective shear strength with time. Based on the interface test results and subsequent slope stability analyses, it is found that the inclusion of a geonet improves the slope stability of a landfill. This could be a potential benefit to the landfill as reinforcement if properly placed. Based on the slope stability analysis on landfills with different slopes, it is concluded that the slope stability of a landfill is improved by keeping the slopes less steep.
Show less - Date Issued
- 2006
- Identifier
- CFE0000919, ucf:46758
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000919
- Title
- SLOPE STABILITY ANALYSIS OF CLASS I LANDFILLS WITH CO DISPOSAL OF BIOSOLIDS USING FIELD TEST DATA.
- Creator
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Vajirkar, Mrutyunjay, Chopra, Dr. Manoj, University of Central Florida
- Abstract / Description
-
Land filling provides a major, safe, and economical disposal route for biosolids and sludges. With an expanding world, the demand for larger and higher capacity landfills is rapidly increasing. Proper analysis and design on such fills have pushed the boundaries of geotechnical engineering practice, in terms of proper identification and assessment of strength and deformation characteristics of waste materials. The engineering properties of Municipal Solid Waste (MSW) with co-disposal of...
Show moreLand filling provides a major, safe, and economical disposal route for biosolids and sludges. With an expanding world, the demand for larger and higher capacity landfills is rapidly increasing. Proper analysis and design on such fills have pushed the boundaries of geotechnical engineering practice, in terms of proper identification and assessment of strength and deformation characteristics of waste materials. The engineering properties of Municipal Solid Waste (MSW) with co-disposal of biosolids and sludges with regards to moisture characteristics and geotechnical stability are of utmost importance. Significant changes in the composition and characteristics of landfill may take place with the addition of sludges and biosolids. In particular, the stability of waste slopes needs to be investigated, which involves the evaluation of the strength properties of the mixture of the waste and biosolids. This thesis deals with impact of the addition of biosolids on the geotechnical properties of class I landfill as determined from field investigations. The geotechnical properties are evaluated using an in-situ deep exploration test, called the Cone Penetration Test (CPT). CPT provides a continuous log of subsurface material properties using two measuring mechanisms, namely, tip resistance and side friction. The areas receiving biosolids are compared with areas without, to evaluate the effect of landfilling of biosolids. The required geotechnical shear strength parameters (angle of internal friction and cohesion) of MSW and biosolids mixture are determined by correlation with CPT results similar to the procedure followed in evaluating soil properties. The shear strength parameters obtained from the CPT data are then used to study the stability of different slope configurations of the landfill. The slope stability analysis is conducted on the various landfill models using the computer software SLOPE/W. This software was designed for soils but was found to be suitable for modeling landfills, as the waste is assumed to act similar to a cohesionless soil. Based on the field investigations, the angle of internal friction was found to be about 29° and the determination of any cohesion was not possible. It was concluded that the most suitable practical solution to adding biosolids into the landfill was in the form of trenches. From the slope stability study, it was found that the factor of safety reduces significantly with the introduction of biosolids due to a reduction in shear strength and increase in the overall moisture content. From a parametric study, the stability of a 1:2 side slope with an angle of friction lower than about 20° was found to be less than the safe limit of 1.5. In addition, the factors of safety for landfills with trenches extending close to the edges of the slopes were also found to be unsafe and this situation needs to be avoided in practice.
Show less - Date Issued
- 2004
- Identifier
- CFE0000301, ucf:46313
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000301
- Title
- An Improved Biosolid Gasifier Model.
- Creator
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McLean, Hannah, Cooper, David, Randall, Andrew, Lee, Woo Hyoung, University of Central Florida
- Abstract / Description
-
As populations increase and cities become denser, the production of waste, both sewage sludge and food biomass, increases exponentially while disposal options for these wastes are limited. Landfills have minimal space for biosolids; countries are now banning ocean disposal methods for fear of the negative environmental impacts. Agricultural application of biosolids cannot keep up with the production rates because of the accumulation of heavy metals in the soils. Gasification can convert...
Show moreAs populations increase and cities become denser, the production of waste, both sewage sludge and food biomass, increases exponentially while disposal options for these wastes are limited. Landfills have minimal space for biosolids; countries are now banning ocean disposal methods for fear of the negative environmental impacts. Agricultural application of biosolids cannot keep up with the production rates because of the accumulation of heavy metals in the soils. Gasification can convert biosolids into a renewable energy source that can reduce the amount of waste heading to the landfills and reduce our dependence on fossil fuels. A recently published chemical kinetic computer model for a fluidized-bed sewage sludge gasifier (Champion, Cooper, Mackie, (&) Cairney, 2014) was improved in this work based on limited experimental results obtained from a bubbling fluidized-bed sewage sludge gasifier at the MaxWest facility in Sanford, Florida and published information from the technical literature. The gasifier processed sewage sludge from the communities surrounding Sanford and was operated at various air equivalence ratios and biosolid feed rates. The temperature profile inside of the gasifier was recorded over the span of four months, and an average profile was used in the base case scenario. The improved model gave reasonable predictions of the axial bed temperature profile, syngas composition, heating value of the syngas, gas flow rate, and carbon conversion. The model was validated by comparing the simulation temperature profile data with the measured temperature profile data. An overall heat loss coefficient was calculated for the gasification unit to provide a more accurate energy balance. Once the model was equipped with a heat loss coefficient, the output syngas temperature closely matched the operational data from the MaxWest facility.The model was exercised at a constant equivalence ratio at varying temperatures, and again using a constant temperature with varying equivalence ratios. The resulting syngas compositions from these exercises were compared to various literature sources. It was decided that some of the reactions kinetics needed to be adjusted so that the change in syngas concentration versus change in bed temperature would more closely match the literature. The reaction kinetics for the Water-Gas Shift and Boudouard reactions were modified back to their original values previously obtained from the literature.
Show less - Date Issued
- 2015
- Identifier
- CFE0005663, ucf:50199
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005663
