Leachate percolating through landfills must be collected and properly treated. However, high concentrations of ammonia (NH4+), refractory organic matter [measured as chemical oxygen demand (COD)], water color and heavy metals in leachate interfere biological processes in conventional wastewater treatment plants. Constructed wetlands (CWs) have been used in the past to treat leachate, but their design and performance has not been properly optimized. In particular, low cost adsorbent materials, such as zeolite and biochar, have the potential to adsorb ammonia and organic compounds, respectively. This increases their retention in the wetland and reduces their toxicity to microorganisms and plants in the ecosystem. In this study, three laboratory-scale recirculating biofilm sequencing batch reactors (RB-SBRs) were set up with the following media materials: 1) lightweight expanded clay aggregate (LECA), 2) LECA + clinoptilolite, a natural zeolite mineral (CZ), 3) LECA + zeolite + biochar (CZB). Reactors were operated in a four-stage sequence to simulate hybrid sub-surface flow wetlands: 1) fill, 2) anoxic react, 3) aerobic react, and 4) decant. The initial hydraulic retention time (HRT) was 14 days and was reduced to 8.75 days after 17 cycles. NH4+, COD, nitrite (NO2-), nitrate (NO3-) and UV456 absorbance were measured to compare the removal performance between RB-SBRs with and without absorbent addition. Substantially higher COD removal was observed in the biochar amended reactor. COD removal of 83% and 61% was observed at HRTs of 14 and 8.75 days, respectively. Higher color removal (95% and 82%) was found in CZB during both HRTs treatment than C and CZ without
even without zeolite addition. Higher effluent NO3- concentrations were observed in CZB, possibly due to lower bioavailability of organic carbon due to adsorption by biochar. Thus, the recommendation for the design of hybrid sub-surface wetlands is to consider the appropriate and economic organic carbon source addition to anoxic phase as an extra electron donor, which can contribute to higher denitrification performance to the completely remove nitrogen from landfill leachate.
|Advisor:||Ergas, Sarina J.|
|Commitee:||Arias, Mauricio E., Zhang, Qiong|
|School:||University of South Florida|
|Department:||Civil and Environmental Engineering|
|School Location:||United States -- Florida|
|Source:||MAI 81/10(E), Masters Abstracts International|
|Keywords:||Adsorption media, Ammonia nitrogen, Chemical oxygen demand, Recirculating biofilm sequencing batch reactors, Ultra-violet (UV) 456|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be