Civil & Environmental Engineering Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2753
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Item INVESTIGATING THE DYNAMICS OF VOLATILE SULFUR COMPOUNDS FROM PRIMARY AND SECONDARY SYSTEMS IN WASTEWATER RESOURCE RECOVERY FACILITIES(2019) Bazemo, Ulrich Yoan Yanick; Torrents, Alba; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study quantifies volatile sulfur compounds (VSCs) emissions from Wastewater Resource Recovery Facilities (WRRFs) and investigate their mechanisms of generation. In primary treatment, of the VSCs analyzed, hydrogen sulfide (H2S) and methyl mercaptan (MM) concentrations in the off gas were dominant, while dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) were under their odor threshold for most sampling dates. H2S emission in primary settling tanks was mainly the result of the stripping of dissolved sulfide (64%) generated in the sewers. MM emission was more dependent on the conditions in the primary clarifiers (only 16% stripping). Most significant prevention of odor emission in primary settling tanks can be achieved by managing biofilms and microbial reactions in the sewer network. This would control the biomass seeding and fermentation product availability in the primary settling tanks directly and will decrease the observed kinetics of H2S and MM production. Overall, management of sludge blanket heights and thus avoiding time at low oxidation reduction potential (ORP) minimized odor emission independent of sewer conditions. Our investigations in secondary reactors have shown that MM was 2 to 3 order of magnitude higher than dissolved MM in primary effluent, revealing that the production of MM took place in the activated sludge process itself, and the stripping of MM from the feed was very minimal. Furthermore, data showed that the depth of secondary sludge blanket plays an important role on the extent of MM emission. At high sludge blanket height, high MM emission was observed. It was concluded that low ORP conditions in sludge blanket, selector zones and RAS was the major source of VSCs. Increasing ORP could decrease odor emissions by targeting the zones where MM is emitted. This could be achieved by addition of nitrate in secondary settling tanks.Item PREVENTION AND TREATMENT OF POLYCHLORINATED BIPHENYLS IN SEDIMENTS - SOURCES AND SOLUTIONS(2019) Jing, Ran; Kjellerup, Birthe Veno; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)PCBs are classified as one of the persistent organic pollutants (POPs) with high toxicity and have undesirable effects on the environment and on humans. Once released into the environment PCBs could bioaccumulate within the food chain, due to their high affinity for organic materials. Recently, studies indicated PCBs can potentially enter a wastewater treatment plant (WWTP) system and be discharged via wastewater effluents thereby further contaminating the downstream environments. This study evaluated the potential for bioremediation of polychlorinated biphenyls (PCBs) in the effluent from a large WWTP. It was found that the continuous effluent was responsible for the majority of the discharged PCB into the receiving river (1821 g for five years), while the intermittent discharge contributed 260 g over the five years. The average number of chlorine per biphenyl for the detected PCB congeners showed a 19% difference between the two types of effluent, which indicated a potential for organohalide respiration of PCBs during the continuous treatment. This was further supported by a high level of tri-, tetra- and penta- chlorinated congeners accounting for 75% of the anaerobically respired PCBs. Potential for aerobic degradation and thus biomineralization of PCBs were identified for both effluents. In addition, the similarity of organohalide respiring (OHR) microbial populations in biosolids and intestinal human biofilms was determined by applying a bioinformatics approach. The OHR populations of the communities were analyzed from existing American and Chinese human intestinal microbiomes. The results of the biosolids analysis showed increased amounts of products from PCB respiration. Simultaneously, experiments with organohalide respiration of PCE in biosolids samples showed significant decreases in PCE concentration after 46 days (28-92%). Subsequently, it was evaluated if the OHR microbial populations in biosolids were similar to those present in intestinal human biofilms by applying a bioinformatic approach. The OHR populations of the communities were analyzed from existing American and Chinese human intestinal microbiomes. The overall groups Proteobacteria, Bacteroides, Actinobacteria, and Firmicutes phyla dominated the microbiomes in all datasets. The OHR groups in biosolids and intestinal biofilms included Dehalogenimonas, Dehalobacter, Desulfitibacter, Desulfovibrio, Sulfurospirillum, Clostridium, and Comamonas. The results of this study showed that several OHR phyla were present in all samples independent of origin. Wastewater and intestinal microbiomes also contained OHR phyla. Finally, biofilms made up by the OHR bacteria Dehalobium chlorocoercia DF-1 were inoculated on the surface of the pinewood biochar particles. The mole percent of the total PCE in the headspace decreased from 100% to 70.4%±17.6% for the rest of nine mesocosms which suggested that the D. chlorocoercia DF-1 biofilm converted PCE to TCE. The gene copy numbers of DF-1 biofilm from nine mesocosms which are ranging from 1.95×108 to 8.30×108 gene copies/g pinewood biochar. The biochar-biofilms were subsequently applied to PCB contaminated sediment from the Grass River in Michigan, USA. The goal was to evaluate the organohalide respiration of the PCB contaminated sediments in the absence/presence of the biofilm and free-floating inoculum.Item Evaluating Gutter Filter Performance After 10 Years Operation(2019) Greenfield, Madeleine; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Urban stormwater runoff contains various pollutants that degrade downstream water quality. Gutter filters, below-grade filtration devices that capture sheet flow, are an ideal stormwater control measure for urban retrofits because of their small footprint. A 10-year-old gutter filter system in Mt. Rainier, MD was monitored for 18 storm events over 13 months for total suspended solids, nitrogen, phosphorus, and copper, zinc, and lead in the downstream stormwater. The filters had received no maintenance since their construction. The stormwater quality was compared to studies conducted prior to installation and immediately after installation of the filters. Total Kjeldahl Nitrogen concentrations displayed a statistically significant increase since installation. All other pollutants did not show a significant change over the 10 years. Nonetheless, overall runoff water quality was not good. Event mean concentrations are comparable to highway runoff and annual pollutant loadings are comparable to untreated runoff from other urban drainage areas in the region.Item REMOVAL OF STORMWATER DISSOLVED ORGANIC NITROGEN MODEL COMPOUNDS THROUGH ADSORPTION AND BIOTRANSFORMATION(2019) Mohtadi, Mehrdad; Davis, Allen P.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bioretention systems are stormwater control measures designed to reduce nitrogen and phosphorus transferred by stormwater to water resources. They are, however, not effectively designed to remove dissolved organic nitrogen (DON). This study concentrated on improvement of bioretention design to remove stormwater DON. Batch adsorption of eight organic nitrogenous compounds onto several adsorbents showed that coal activated carbon (AC) could be a reliable adsorbent for removal of organic nitrogenous compounds such as pyrrole and N-acetyl-D-glucosamine (NAG). The adsorption capacity of pyrrole and NAG on coal AC were 0.4 mg N/g (at equilibrium concentration, Ce = 0.02 mg N/L) and 0.71 mg N/g (at Ce = 1 mg N/L), respectively. These eight nitrogenous compounds were also tested for continuous column adsorption on a media mixture of coal AC + quartz sand, and only pyrrole showed an appreciable adsorption performance; the breakthrough and exhaustion depths for pyrrole were 88 and 499 m, respectively, at the fixed superficial velocity of 61 cm/h and influent DON concentration of 1 mg N/L. Pyrrole adsorption was also minimally affected by superficial velocity (DON removal efficiency stayed > 91% for all tested superficial velocities, 7 to 489 cm/h). Because the adsorption process was successful for removal of only one (pyrrole) out of eight examined compounds, biological treatment was also investigated for removal of organic nitrogenous compounds. Biotransformation alongside adsorption demonstrated benefits such as ammonification of bio-recalcitrant organic nitrogen compounds, e.g., pyrrole, and bioregeneration of the adsorbent (coal AC). According to the results, ammonifiction might be considered as a possible reliable mechanism for stormwater DON removal at low temperatures > 4°C. Under intermittent wetting/draining conditions, the effluent DON was less than 0.1 mg N/L after the applied depth of 48 m, indicating that DON was successfully removed through simultaneous adsorption/ammonification, although generated ammonium in the effluent must be properly addressed. Overall, based on the results from the current study, some DON types were strongly adsorbed by adsorbents, e.g., adsorption of pyrrole on coal AC, some were more bioavailable, e.g., ammonification of leucine, and some were barely adsorbable and bioavailable, e.g., Aldrich humic acid on coal AC. Accordingly, both adsorption and biotransformation should be considered to enhance stormwater DON removal as much as possible.Item SOLUBLE SALTS REDUCTION AND METALS BEHAVIOR OF DREDGED SEDIMENT FOR REUSE IN HIGHWAY SLOPE APPLICATIONS(2019) Huffert, Michelle B; Davis, Allen P.; Aydilek, Ahmet H.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Waterways are dredged routinely to maintain navigation channels, resulting in large quantities of dredged materials (DM) that require disposal. This study examines the innovative reuse of DM as a topsoil alternative in highway slopes. The dredged material met Maryland Department of Transportation, State Highway Administration (MDOT SHA) topsoil requirements for pH, organic matter, and particle size distribution, and required 122 cm (48 inches) of rainwater to leach soluble salts to below limits. Column leach tests were performed on DM and topsoil to evaluate metal leaching behavior; extractions were performed to determine total and potentially mobile metals content. DM leached metals concentrations below drinking water maximum contaminant levels (MCLs) for >95% of the samples tested, and passed a toxicity characteristic leaching procedure (TCLP). Extraction data showed higher total concentrations of arsenic, chromium, and lead as compared to topsoil, but similar concentrations in the EDTA-extracted fractions indicating that metals are strongly bound.Item Evaluation of treatment and resource recovery potential of bioelectrochemical systems to DC Water process streams by bench and pilot system(2018) Leininger, Aaron Matthew; Kjellerup, Birthe V; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Microbial fuel cell and microbial electrolysis cell systems were developed and tested with different wastewater process streams from DC Water Blue Plains Advanced Wastewater Treatment Plant. These biofilm-based systems provide an alternative to the conventional activated sludge system by oxidizing wastewater organics without the need for mechanical aeration. In bench-scale systems, the application of high-strength solids-dewatering wastewater as a feedstock was shown to increase both treatment energy savings and energy recovery. Current densities in meso-scale microbial electrolysis cells were 3.3 and 3.6 times higher when fed dewatering-filtrate or a blend of filtrate and primary effluent as compared to reactors operating with primary effluent. An integrated 800L pilot biocathode microbial fuel cell system was designed and constructed, and initial results are reported. Over the first 43 days of operation, the system averaged 15% removal of chemical oxygen demand and a load removal of 110 g_tCOD/(m^3*day).Item LOW IMPACT DEVELOPMENT MIXTURE EVALUATION FOR HEAVY METAL REMOVAL(2019) Liang, Liang; Davis, Allen P.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)To address non-point heavy metal pollutant sources to urban stormwater runoff, the LIDMATTM (Low Impact Development MAT) is a stormwater management runoff system designed and manufactured for effective treatment for heavy metals. The LIDMATTM contains approximately 70% sand, 25% manure compost, and 5% steel slag by mass. The LIDMATTM was evaluated based on flow rate, pH, heavy metal removal, and the concentrations of N and P leached; conditions for optimum removal have been quantified. For treating synthetic stormwater runoff, 12 trials were completed using bench-scale and column media testing systems. Average effluent event mean concentrations of all trials were 25 ± 10 μg/L Cu, 21 ± 13 μg/L Pb, and 57 ± 42 μg/L Zn from studies at influent concentrations of 500 μg/L, 300 μg/L, and 100 μg/L, which satisfy Numeric Action Levels (NALs) of Cu, Pb, and Zn by the state of California, USA, Industrial General Permit (IGP). The leaching of nitrogen and phosphorous were also below the NALs.Item IMPROVING STORMWATER QUALITY USING A NOVEL PERMEABLE PAVEMENT BASE MATERIAL(2018) OSTROM, TRAVIS Kyle; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A novel stormwater treatment media has been developed using expanded shale aggregate, Al-based water treatment residual (WTR), and psyllium-based binder. The media (HPMM) has sufficient structural capacity and hydraulic conductivity to serve as a permeable pavement base material and demonstrated effective phosphorus (P) retention in lab- and field-scale studies. Long-term adsorption capacity is projected to exceed 600 years of useful life before P saturation under conditions typical of urban stormwater in Maryland (i.e., 0.20 mg/L dissolved P (DP) influent and 100 cm of direct rainfall per year). A dynamic model was developed to describe DP adsorption onto the media based on lab testing and verified under field monitoring. The model predicted 62% DP concentration reduction and 65% DP mass load reduction. Actual reductions from 17 months of monitoring in a field pilot study were 67% for DP concentration and 69% DP mass load. Total Cu and Zn were also removed from stormwater in lab and field studies. Percent concentration reductions of 59-69% for Cu and 78-90% for Zn were shown in lab studies using synthetic stormwater. Mass load was reduced in field monitoring by 32 and 21% for Cu and Zn, respectively. WTR in the media was shown to be a potential source of nitrogen (N). An internal water storage (IWS) zone was established in a 5-cm permeable pavement base layer to mitigate N export by promoting denitrification. The IWS was shown to effectively lower N concentrations in simulated stormwater when carbon (C) was available in excess (~10 mg/L total C as C). Elevated Al concentrations were found in some filtrate samples from the field study, resulting from washout of fines from the media. Improved HPMM mix preparation methods have been developed and are critical to prevent Al washout and export. This research resulted in development of the first known enhanced stormwater treatment media to retain DP in a permeable pavement base layer. With appropriate N and Al control, the novel media can be an effective tool and can enhance permeable pavements to improve urban stormwater quality.Item IMPACT OF PERIODIC HIGH CONCENTRATIONS OF SALTS ON BIORETENTION NUTRIENTS PERFORMANCE(2018) McManus, Meigan; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bioretention is a stormwater control measure commonly used to remove pollutants, including nitrogen (N) and phosphorus (P), from urban runoff. This project seeks to evaluate the impacts of high concentrations of sodium chloride (NaCl) deicer on bioretention N and P removal performances. Bioretention mesocosm studies were conducted to examine N and P removal efficiencies following periodic 2,000, 5,000, and 10,000 mg/L NaCl salt applications. Episodic washouts of TSS, N and P, likely due to ion exchange with the sodium and chloride ions, were observed for all three columns and mass export of P was observed for the 2,000 and 5,000 mg/L NaCl columns after 26 m and 7 m applied water, respectively. No mass N export was observed. Based on a mass balance of N and P, it is recommended to limit the use of deicers to prevent long-term P export.Item USING A HIGH ORGANIC-MATTER PERMEABLE REACTIVE BARRIER TO REMEDIATE TRICHLOROETHYLENE-CONTAMINATED GROUNDWATER AT THE BEAVER DAM ROAD LANDFILL(2018) Nino de Guzman, Gabriela Tejeda; Kjellerup, Birthe V; Torrents, Alba; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Trichloroethylene (TCE) is an effective industrial degreaser and known carcinogen. It was frequently improperly disposed of and has become one of the most common groundwater and soil contaminants in the USA. Clean up continues to be difficult due to its physical and chemical properties. TCE and several of its degradation products were detected in the groundwater of the Beaver Dam Road Landfill (Beltsville, MD) at concentrations above their maximum contaminant levels (MCLs). The US Department of Agriculture-Agricultural Research Service together with the University of Maryland, College Park and BMT Designers and Planners designed a permeable reactive barrier, or biowall, to remediate the contaminated groundwater. A series of batch reactor studies were conducted at 12°C to examine biowall fill-material combinations including the effects of zero-valent iron (ZVI) and glycerol amendments. Headspace samples were analyzed over the course of several months to monitor TCE degradation. An unamended, 4:3 mulch-to-compost combination was chosen based on no detectable TCE at the conclusion of the experiment. To increase the biowall degradation capacity, microbial infiltration and colonization of the structure were also studied. PCR, qPCR, and next-generation sequencing were used to survey the site’s indigenous population for dechlorinating clusters. Numerous clusters were identified affirming the use of the native population for bioaugmentation efforts. The ability of the biowall to support said community was investigated by monitoring continuously-fed column reactors containing biowall material spiked with a commercially-available, surrogate population, with and without a 5 mg/L dose of ZVI. The groundwater-fed column sans ZVI had the greatest Dehalococcoides population and while ZVI without biostimulation did decrease the overall population, it did not cause a statistically significant difference. Thus, if ZVI were to be used as a future biowall amendment, biostimulation would not be required to maintain a dechlorinating population. A sacrificial carbon source may be necessary to slow the biological degradation of the biowall’s organic fill-material. These findings will be utilized in future remediation and/or biowall expansion plans to fully employ the site’s natural resources. The biowall was constructed in July 2013 containing the 4:3 mulch-to-compost ratio and has reduced the upstream TCE concentration by ~90%.