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Wang, B. (2016). Aerated Recirculation and Pressurized Suspended Fiber Biofiltration for the Treatment of Landfill
Leachate. Retrieved from http://purl.flvc.org/fsu/fd/FSU_2016SP_Wang_fsu_0071N_13128
ABSTRACT Landfilling is widely adopted as one of the most economical processes for solid waste disposal. At the same time, landfill leachate is also a great environmental concern because of its complex composition and high contaminant concentrations. Recirculating leachate appears to be one of the least expensive methods for partial treatment and disposal of leachate at properly designed and operated landfill sites. The leachate recirculation not only improves the leachate quality, but also shortens the time duration required for landfill stabilization. In addition, aerated leachate recirculation can bring air into the landfill, leading to aerobic organic decomposition, as well as iron precipitation. It has been discovered that up to 84% BOD, 86% COD, 90% iron and manganese can be removed after 4 months' recirculation. In Northwest Florida, high concentrations of iron have been observed in the landfill leachate, which is believed to be released to the landfill leachate from iron-rich soil owing to changes in pH and redox conditions induced by organic waste decomposition. Therefore, aerated leachate recirculation has obvious benefits in this region. Although aerated leachate recirculation has these advantages, leachate is only partially treated. The leachate must be further treated in order to meet the discharge requirements. Among all the treatment methods, biological treatment of wastewater with a biofilter is the most promising and most well characterized technology. During biofiltration operations, the growth of microorganisms develops biofilms on the medium surfaces and the microorganisms in the biofilms absorb soluble and colloidal waste materials in the wastewater as it percolates over the medium surfaces. The BOD can nearly be completely removed if the wastewater retention time in the media is sufficiently long for the microorganisms to absorb wastewater constituents. In this research, aerated recirculation and pressurized suspended fiber biofiltration were tested for the treatment of leachate from landfills in Northwest Florida. The pressurized suspended biofilter can efficiently achieve the filtration function with limited space. The suspended fiber provide a tremendous amount of surface areas in a small volume. Therefore, microorganisms can grow around the fibers at a density of greater than 1 × 108 cells per ml, the only means to culture cells at in vivo-like cell density. Another advantage of the pressurized suspended fiber filtration is that the oxygen transfer barrier can be overcome and consequently significantly increased dissolved oxygen level can be achieved. As an innovative technology for wastewater treatment, the pressurized suspended fiber biofilters also makes biological contact oxidation possible, which can significantly improve BOD and COD removal and decrease the sludge yield. For iron removal, contact oxidation is achieved by microbial mediated iron oxidation and fixation during which ferrous iron is oxidized to ferric iron and fixed onto the filter media. Consequently, there is minimal ferric iron suspending in the solution that can escape the filter. Using the combined aerated leachate recirculation and pressurized fiber biofiltration, chemical oxygen demand (COD) of the landfill leachate can be reduced to as low as 8 mg/l and iron content can be reduced to as low as 0.02 mg/l under appropriate dissolved oxygen and alkalinity conditions.
A Thesis submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the Master of Science.
Bibliography Note
Includes bibliographical references.
Advisory Committee
Gang Chen, Professor Directing Thesis; Wenrui Huang, Committee Member; Youneng Tang, Committee Member.
Publisher
Florida State University
Identifier
FSU_2016SP_Wang_fsu_0071N_13128
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Wang, B. (2016). Aerated Recirculation and Pressurized Suspended Fiber Biofiltration for the Treatment of Landfill
Leachate. Retrieved from http://purl.flvc.org/fsu/fd/FSU_2016SP_Wang_fsu_0071N_13128