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Description
To address sustainability issues in wastewater treatment (WWT), Siemens Water Technologies (SWT) has designed a "hybrid" process that couples common activated sludge (AS) and anaerobic digestion (AD) technologies with the novel concepts of AD sludge recycle and biosorption. At least 85% of the hybrid's AD sludge is recycled to the

To address sustainability issues in wastewater treatment (WWT), Siemens Water Technologies (SWT) has designed a "hybrid" process that couples common activated sludge (AS) and anaerobic digestion (AD) technologies with the novel concepts of AD sludge recycle and biosorption. At least 85% of the hybrid's AD sludge is recycled to the AS process, providing additional sorbent for influent particulate chemical oxygen demand (PCOD) biosorption in contact tanks. Biosorbed PCOD is transported to the AD, where it is converted to methane. The aim of this study is to provide mass balance and microbial community analysis (MCA) of SWT's two hybrid and one conventional pilot plant trains and mathematical modeling of the hybrid process including a novel model of biosorption. A detailed mass balance was performed on each tank and the overall system. The mass balance data supports the hybrid process is more sustainable: It produces 1.5 to 5.5x more methane and 50 to 83% less sludge than the conventional train. The hybrid's superior performance is driven by 4 to 8 times longer solid retention times (SRTs) as compared to conventional trains. However, the conversion of influent COD to methane was low at 15 to 22%, and neither train exhibited significant nitrification or denitrification. Data were inconclusive as to the role of biosorption in the processes. MCA indicated the presence of Archaea and nitrifiers throughout both systems. However, it is inconclusive as to how active Archaea and nitrifiers are under anoxic, aerobic, and anaerobic conditions. Mathematical modeling confirms the hybrid process produces 4 to 20 times more methane and 20 to 83% less sludge than the conventional train under various operating conditions. Neither process removes more than 25% of the influent nitrogen or converts more that 13% to nitrogen gas due to biomass washout in the contact tank and short SRTs in the stabilization tank. In addition, a mathematical relationship was developed to describe PCOD biosorption through adsorption to biomass and floc entrapment. Ultimately, process performance is more heavily influenced by the higher AD SRTs attained when sludge is recycled through the system and less influenced by the inclusion of biosorption kinetics.
ContributorsYoung, Michelle Nichole (Author) / Rittmann, Bruce E. (Thesis advisor) / Fox, Peter (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Arizona State University (Publisher)
Created2011
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Description
Intimate coupling of Ti2 photocatalysis and biodegradation (ICPB) offers potential for degrading biorecalcitrant and toxic organic compounds much better than possible with conventional wastewater treatments. This study reports on using a novel sponge-type, Ti2-coated biofilm carrier that shows significant adherence of Ti2 to its exterior and the ability to accumulate

Intimate coupling of Ti2 photocatalysis and biodegradation (ICPB) offers potential for degrading biorecalcitrant and toxic organic compounds much better than possible with conventional wastewater treatments. This study reports on using a novel sponge-type, Ti2-coated biofilm carrier that shows significant adherence of Ti2 to its exterior and the ability to accumulate biomass in its interior (protected from UV light and free radicals). First, this carrier was tested for ICPB in a continuous-flow photocatalytic circulating-bed biofilm reactor (PCBBR) to mineralize biorecalcitrant organic: 2,4,5-trichlorophenol (TCP). Four mechanisms possibly acting of ICPB were tested separately: TCP adsorption, UV photolysis/photocatalysis, and biodegradation. The carrier exhibited strong TCP adsorption, while photolysis was negligible. Photocatalysis produced TCP-degradation products that could be mineralized and the strong adsorption of TCP to the carrier enhanced biodegradation by relieving toxicity. Validating the ICPB concept, biofilm was protected inside the carriers from UV light and free radicals. ICPB significantly lowered the diversity of the bacterial community, but five genera known to biodegrade chlorinated phenols were markedly enriched. Secondly, decolorization and mineralization of reactive dyes by ICPB were investigated on a refined Ti2-coated biofilm carrier in a PCBBR. Two typical reactive dyes: Reactive Black 5 (RB5) and Reactive Yellow 86 (RY86), showed similar first-order kinetics when being photocatalytically decolorized at low pH (~4-5), which was inhibited at neutral pH in the presence of phosphate or carbonate buffer, presumably due to electrostatic repulsion from negatively charged surface sites on Ti2, radical scavenging by phosphate or carbonate, or both. In the PCBBR, photocatalysis alone with Ti2-coated carriers could remove RB5 and COD by 97% and 47%, respectively. Addition of biofilm inside macroporous carriers maintained a similar RB5 removal efficiency, but COD removal increased to 65%, which is evidence of ICPB despite the low pH. A proposed ICPB pathway for RB5 suggests that a major intermediate, a naphthol derivative, was responsible for most of the residual COD. Finally, three low-temperature sintering methods, called O, D and DN, were compared based on photocatalytic efficiency and Ti2 adherence. The DN method had the best Ti2-coating properties and was a successful carrier for ICPB of RB5 in a PCBBR.
ContributorsLi, Guozheng (Author) / Rittmann, Bruce E. (Thesis advisor) / Halden, Rolf (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Arizona State University (Publisher)
Created2011
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Description
This study reports on benzene and toluene biodegradation under different dissolved oxygen conditions, and the goal of this study is to evaluate and model their removal.

Benzene and toluene were tested for obligate anaerobic degradation in batch reactors with sulfate as the electron acceptor. A group of sulfate-reducing bacteria capable

This study reports on benzene and toluene biodegradation under different dissolved oxygen conditions, and the goal of this study is to evaluate and model their removal.

Benzene and toluene were tested for obligate anaerobic degradation in batch reactors with sulfate as the electron acceptor. A group of sulfate-reducing bacteria capable of toluene degradation was enriched after 252 days of incubation. Those cultures, originated from anaerobic digester, were able to degrade toluene coupled to sulfate reduction with benzene coexistence, while they were not able to utilize benzene. Methanogens also were present, although their contribution to toluene biodegradation was not defined.

Aerobic biodegradation of benzene and toluene by Pseudomonas putida F1 occurred, and biomass production lagged behind substrate loss and continued after complete substrate removal. This pattern suggests that biodegradation of intermediates, rather than direct benzene and toluene transformation, caused bacterial growth. Supporting this explanation is that the calculated biomass growth from a two-step model basically fit the experimental biomass results during benzene and toluene degradation with depleted dissolved oxygen.

Catechol was tested for anaerobic biodegradation in batch experiments and in a column study. Sulfate- and nitrate-reducing bacteria enriched from a wastewater treatment plant hardly degraded catechol within 20 days. However, an inoculum from a contaminated site was able to remove 90% of the initial 16.5 mg/L catechol, and Chemical Oxygen Demand was oxidized in parallel. Catechol biodegradation was inhibited when nitrite accumulated, presumably by a toxic catechol-nitrite complex.

The membrane biofilm reactor (MBfR) offers the potential for biodegrading benzene in a linked aerobic and anaerobic pathway by controlling the O2 delivery. At an average benzene surface loading of 1.3 g/m2-day and an average hydraulic retention time of 2.2 day, an MBfR supplied with pure O2 successfully achieved 99% benzene removal at steady state. A lower oxygen partial pressure led to decreased benzene removal, and nitrate removal increased, indicating multiple mechanisms, including oxygenation and nitrate reduction, were involved in the system being responsible for benzene removal. Microbial community analysis indicated that Comamonadaceae, a known aerobic benzene-degrader and denitrifier, dominated the biofilm at the end of operation.
ContributorsLiu, Zhuolin (Author) / Rittmann, Bruce E. (Thesis advisor) / Krajmalnik-Brown, Rosa (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2015
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Description
Widespread use of chlorinated solvents for commercial and industrial purposes makes co-occurring contamination by 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and 1,4-dioxane (1,4-D) a serious problem for groundwater. TCE and TCA often are treated by reductive dechlorination, while 1,4-D resists reductive treatment. Aerobic bacteria are able to oxidize 1,4-D, but

Widespread use of chlorinated solvents for commercial and industrial purposes makes co-occurring contamination by 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and 1,4-dioxane (1,4-D) a serious problem for groundwater. TCE and TCA often are treated by reductive dechlorination, while 1,4-D resists reductive treatment. Aerobic bacteria are able to oxidize 1,4-D, but the biological oxidation of 1,4-D could be inhibited TCA, TCE, and their reductive transformation products. To overcome the challenges from co-occurring contamination, I propose a two-stage synergistic system. First, anaerobic reduction of the chlorinated hydrocarbons takes place in a H2-based hollow-fiber “X-film” (biofilm or catalyst-coated film) reactor (MXfR), where “X-film” can be a “bio-film” (MBfR) or an abiotic “palladium-film” (MPfR). Then, aerobic removal of 1,4-D and other organic compounds takes place in an O2-based MBfR. For the reductive part, I tested reductive bio-dechlorination of TCA and TCE simultaneously in an MBfR. I found that the community of anaerobic bacteria can rapidly reduce TCE to cis-dichloroethene (cis-DCE), but further reductions of cis-DCE to vinyl chloride (VC) and VC to ethene were inhibited by TCA. Also, it took months to grow a strong biofilm that could reduce TCA and TCE. Another problem with reductive dechlorination in the MBfR is that mono-chloroethane (MCA) was not reduced to ethane. In contrast, a film of palladium nano-particles (PdNPs), i.e., an MPfR, could the simultaneous reductions of TCA and TCE to mainly ethane, with only small amounts of intermediates: 1,1-dichloroethane (DCA) (~3% of total influent TCA and TCE) and MCA (~1%) in continuous operation. For aerobic oxidation, I enriched an ethanotrophic culture that could oxidize 1,4-D with ethane as the primary electron donor. An O2-based MBfR, inoculated with the enriched ethanotrophic culture, achieved over 99% 1,4-D removal with ethane as the primary electron donor in continuous operation. Finally, I evaluated two-stage treatment with a H2-based MPfR followed by an O2-MBfR. The two-stage system gave complete removal of TCA, TCE, and 1,4-D in continuous operation.
ContributorsLuo, Yihao (Author) / Rittmann, Bruce E. (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Zhou, Chen (Committee member) / Arizona State University (Publisher)
Created2018
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Description
The application of microalgal biofilms in wastewater treatment has great advantages such as abolishing the need for energy intensive aerators and recovering nutrients as energy, thus reducing the energy requirement of wastewater treatment several-fold. A 162 cm2 algal biofilm reactor with good wastewater treatment performance and a regular harvesting procedure

The application of microalgal biofilms in wastewater treatment has great advantages such as abolishing the need for energy intensive aerators and recovering nutrients as energy, thus reducing the energy requirement of wastewater treatment several-fold. A 162 cm2 algal biofilm reactor with good wastewater treatment performance and a regular harvesting procedure was studied at lab scale to gain an understanding of effectual parameters such as hydraulic retention time (HRT; 2.6 and 1.3 hrs), liquid level (LL; 0.5 and 1.0 cm), and solids retention time (SRT; 3 and 1.5 wks). A revised synthetic wastewater “Syntho 3.7” was used as a surrogate of domestic primary effluent for nutrient concentration consistency in the feed lines. In the base case (2.6 hr HRT, 0.5 cm LL, and 3 wk SRT), percent removals of 69 ± 2 for total nitrogen (TN), 54 ± 21 for total phosphorous (TP), and 60 ± 7 for chemical oxygen demand (COD) were achieved and 4.0 ± 1.6 g/m2/d dry biomass was produced. A diffusion limitation was encountered when increasing the liquid level, while the potential to further decrease the HRT remains. Nonlinear growth kinetics was observed in comparing SRT variations, and promoting autotrophic growth seems possible. Future work will look towards producing a mathematical model and further testing the aptness of this system for large-scale implementation.
ContributorsHalloum, Ibrahim (Author) / Torres, César I (Thesis advisor) / Popat, Sudeep C (Committee member) / Rittmann, Bruce E. (Committee member) / Arizona State University (Publisher)
Created2016
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Description
Zero-Valent Metals (ZVM) are highly reactive materials and have been proved to be effective in contaminant reduction in soils and groundwater remediation. In fact, zero-Valent Iron (ZVI) has proven to be very effective in removing, particularly chlorinated organics, heavy metals, and odorous sulfides. Addition of ZVI has also been proved

Zero-Valent Metals (ZVM) are highly reactive materials and have been proved to be effective in contaminant reduction in soils and groundwater remediation. In fact, zero-Valent Iron (ZVI) has proven to be very effective in removing, particularly chlorinated organics, heavy metals, and odorous sulfides. Addition of ZVI has also been proved in enhancing the methane gas generation in anaerobic digestion of activated sludge. However, no studies have been conducted regarding the effect of ZVM stimulation to Municipal Solid Waste (MSW) degradation. Therefore, a collaborative study was developed to manipulate microbial activity in the landfill bioreactors to favor methane production by adding ZVMs. This study focuses on evaluating the effects of added ZVM on the leachate generated from replicated lab scale landfill bioreactors. The specific objective was to investigate the effects of ZVMs addition on the organic and inorganic pollutants in leachate. The hypothesis here evaluated was that adding ZVM including ZVI and Zero Valent Manganese (ZVMn) will enhance the removal rates of the organic pollutants present in the leachate, likely by a putative higher rate of microbial metabolism. Test with six (4.23 gallons) bioreactors assembled with MSW collected from the Salt River Landfill and Southwest Regional Landfill showed that under 5 grams /liter of ZVI and 0.625 grams/liter of ZVMn additions, no significant difference was observed in the pH and temperature data of the leachate generated from these reactors. The conductivity data suggested the steady rise across all reactors over the period of time. The removal efficiency of sCOD was highest (27.112 mg/lit/day) for the reactors added with ZVMn at the end of 150 days for bottom layer, however the removal rate was highest (16.955 mg/lit/day) for ZVI after the end of 150 days of the middle layer. Similar trends in the results was observed in TC analysis. HPLC study indicated the dominance of the concentration of heptanoate and isovalerate were leachate generated from the bottom layer across all reactors. Heptanoate continued to dominate in the ZVMn added leachate even after middle layer injection. IC analysis concluded the chloride was dominant in the leachate generated from all the reactors and there was a steady increase in the chloride content over the period of time. Along with chloride, fluoride, bromide, nitrate, nitrite, phosphate and sulfate were also detected in considerable concentrations. In the summary, the addition of the zero valent metals has proved to be efficient in removal of the organics present in the leachate.
ContributorsPandit, Gandhar Abhay (Author) / Cadillo – Quiroz, Hinsby (Thesis advisor) / Olson, Larry (Thesis advisor) / Boyer, Treavor (Committee member) / Arizona State University (Publisher)
Created2019
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Description
Seeking to address sustainability issues associated with food waste (FW), and fat, oil, and grease (FOG) waste disposal, the City of Mesa commissioned the Biodesign Swette Center for Environmental Biotechnology (BSCEB) at Arizona State University (ASU) to study to the impact of implementing FW/FOG co-digestion at the wastewater treatment plant

Seeking to address sustainability issues associated with food waste (FW), and fat, oil, and grease (FOG) waste disposal, the City of Mesa commissioned the Biodesign Swette Center for Environmental Biotechnology (BSCEB) at Arizona State University (ASU) to study to the impact of implementing FW/FOG co-digestion at the wastewater treatment plant (WWTP). A key issue for the study was the “souring” of the anaerobic digesters (ADs), which means that the microorganism responsible for organic degradation were deactivated, causing failure of the AD. Several bench-scale reactors soured after the introduction of the FW/FOG feed streams. By comparing measurements from stable with measurements from the souring reactors, I identified two different circumstances responsible for souring events. One set of reactors soured rapidly after the introduction of FW/FOG due to the digester’s hydraulic retention times (HRT) becoming too short for stable operation. A second set of reactors soured after a long period of stability due to steady accumulation of fatty acids (FAs) that depleted bicarbonate alkalinity. FA accumulation was caused by the incomplete hydrolysis/fermentation of feedstock protein, leading to insufficient release of ammonium (NH4+). In contrast, carbohydrates were more rapidly hydrolyzed and fermented to FAs.

The most important contribution of my research is that I identified several leading indicators of souring. In all cases of souring, the accumulation of soluble chemical oxygen demand (SCOD) was an early and easily quantified indicator. A shift in effluent FA concentrations from shorter to longer species also portended souring. A reduction in the yield of methane (CH4) per mass of volatile suspended solids removed (VSSR) also identified souring conditions, but its variability prevented the methane yield from providing advanced warning to allow intervention. For the rapidly soured reactors, reduced bicarbonate alkalinity was the most useful warning sign, and an increasing ratio of SCOD to bicarbonate alkalinity was the clearest sign of souring. Because I buffered the slow-souring reactors with calcium carbonate (CaCO3), I could not rely on bicarbonate alkalinity as an indicator, which put a premium on SCOD as the early warning. I implemented two buffering regimes and demonstrated that early and consistent buffering could lead to reactor recovery.
ContributorsKupferer III, Rick Anthony (Author) / Rittmann, Bruce E. (Thesis advisor) / Young, Michelle N (Committee member) / Torres, César I (Committee member) / Arizona State University (Publisher)
Created2020
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Description
Large-scale cultivation of photosynthetic microorganisms for the production of biodiesel and other valuable commodities must be made more efficient. Recycling the water and nutrients acquired from biomass harvesting promotes a more sustainable and economically viable enterprise. This study reports on growing the cyanobacterium Synechocystis sp. PCC 6803 using

Large-scale cultivation of photosynthetic microorganisms for the production of biodiesel and other valuable commodities must be made more efficient. Recycling the water and nutrients acquired from biomass harvesting promotes a more sustainable and economically viable enterprise. This study reports on growing the cyanobacterium Synechocystis sp. PCC 6803 using permeate obtained from concentrating the biomass by cross-flow membrane filtration. I used a kinetic model based on the available light intensity (LI) to predict biomass productivity and evaluate overall performance.

During the initial phase of the study, I integrated a membrane filter with a bench-top photobioreactor (PBR) and created a continuously operating system. Recycling permeate reduced the amount of fresh medium delivered to the PBR by 45%. Biomass production rates as high as 400 mg-DW/L/d (9.2 g-DW/m2/d) were sustained under constant lighting over a 12-day period.

In the next phase, I operated the system as a sequencing batch reactor (SBR), which improved control over nutrient delivery and increased the concentration factor of filtered biomass (from 1.8 to 6.8). I developed unique system parameters to compute the amount of recycled permeate in the reactor and the actual hydraulic retention time during SBR operation. The amount of medium delivered to the system was reduced by up to 80%, and growth rates were consistent at variable amounts of repeatedly recycled permeate. The light-based model accurately predicted growth when biofilm was not present. Coupled with mass ratios for PCC 6803, these predictions facilitated efficient delivery of nitrogen and phosphorus. Daily biomass production rates and specific growth rates equal to 360 mg-DW/L/d (8.3 g/m2/d) and 1.0 d-1, respectively, were consistently achieved at a relatively low incident LI (180 µE/m2/s). Higher productivities (up to 550 mg-DW/L/d) occurred under increased LI (725 µE/m2/s), although the onset of biofilm impeded modeled performance.

Permeate did not cause any gradual growth inhibition. Repeated results showed cultures rapidly entered a stressed state, which was followed by widespread cell lysis. This phenomenon occurred independently of permeate recycling and was not caused by nutrient starvation. It may best be explained by negative allelopathic effects or viral infection as a result of mixed culture conditions.
ContributorsThompson, Matthew (Author) / Rittmann, Bruce E. (Thesis advisor) / Fox, Peter (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Arizona State University (Publisher)
Created2015