This study is aimed to provide comprehensive evaluation and mechanistic understanding of the impact of process intensification techniques applied in main and side stream wastewater treatment on biosolids management in terms of anaerobic digestion enhancement, dewaterability improvement, odor mitigation, as well as phosphorus and nitrogen removal. The first part of this study was conducted to understand the effect of anaerobic digester solids retention time (SRT) on odor emission from biosolids. A kinetic model and inhibitory studies showed the emission of methanethiol (MT), a representative odor compound, was primarily determined by the dynamic concurrence of MT production from amino acid and utilization by methanogens in the course of anaerobic digestion. MT emission pattern follows a bell-shape curve with SRT in anaerobic digesters. However, for digested and dewatered biosolids, SRT ranging from 15 to 50 days in anaerobic digesters demonstrated insignificant effect on the odor emission from biosolids. In contrast, the peak odor emission was found to exponentially increase with both shear intensity and polymer dose applied during dewatering. The second part of this study investigated the impact of process intensification practices on sludge dewatering performance. The integration of high-rate activated sludge process and anaerobic digestion elevated the sludge orthophosphate level, leading to struvite scaling and dewaterability deterioration. Superior orthophosphate removal, significant improvement of sludge dewaterability, and favorable economics were achieved through sludge conditioning by cerium chloride. Continuous flow aerobic granulation technology offered significant process intensification of mainstream treatment trains. However, its impact on biosolids management was not studied. This study showed that there was little dewaterability difference between aerobic granular sludge and activated sludge when polymer was not added. However, about 75% polymer saving and improved dewatering performance were observed with polymer addition. When subjected to high shear, a greater dewaterability deterioration was observed for granular sludge than activated sludge. The last part of this study is focused on the impact of anaerobic digestion process intensification through thermal treatment including pre-pasteurization, thermophilic anaerobic digestion, temperature phased anaerobic digestion, and thermal hydrolysis pretreatment. Improved methane production, pathogen reduction, dewatering performance, and odor mitigation were observed with the involvement of these high-temperature processes. However, special cautions and measure should be taken during the start-up of these high rate processes as they are more liable to digester souring. In addition, the in-depth understanding of the mechanism of recalcitrant dissolved organic nitrogen formation during sludge thermal pretreatment was provided. / Doctor of Philosophy / This study is aimed to provide comprehensive evaluation and mechanistic understanding of the impact of process intensification techniques applied in main and side stream wastewater treatment on biosolids management in terms of anaerobic digestion enhancement, dewaterability improvement, odor mitigation, as well as phosphorus and nitrogen removal. The first part of this study was conducted to understand the effect of anaerobic digester solids retention time (SRT) on odor emission from biosolids. A kinetic model and inhibitory studies showed the emission of methanethiol (MT), a representative odor compound, was primarily determined by the dynamic concurrence of MT production from amino acid and utilization by methanogens in the course of anaerobic digestion. MT emission pattern follows a bell-shape curve with SRT in anaerobic digesters. However, for digested and dewatered biosolids, SRT ranging from 15 to 50 days in anaerobic digesters demonstrated insignificant effect on the odor emission from biosolids. In contrast, the peak odor emission was found to exponentially increase with both shear intensity and polymer dose applied during dewatering. The second part of this study investigated the impact of process intensification practices on sludge dewatering performance. The integration of high-rate activated sludge process and anaerobic digestion elevated the sludge orthophosphate level, leading to struvite scaling and dewaterability deterioration. Superior orthophosphate removal, significant improvement of sludge dewaterability, and favorable economics were achieved through sludge conditioning by cerium chloride. Continuous flow aerobic granulation technology offered significant process intensification of mainstream treatment trains. However, its impact on biosolids management was not studied. This study showed that there was little dewaterability difference between aerobic granular sludge and activated sludge when polymer was not added. However, about 75% polymer saving and improved dewatering performance were observed with polymer addition. When subjected to high shear, a greater dewaterability deterioration was observed for granular sludge than activated sludge. The last part of this study is focused on the impact of anaerobic digestion process intensification through thermal treatment including pre-pasteurization, thermophilic anaerobic digestion, temperature phased anaerobic digestion, and thermal hydrolysis pretreatment. Improved methane production, pathogen reduction, dewatering performance, and odor mitigation were observed with the involvement of these high-temperature processes. However, special cautions and measure should be taken during the start-up of these high rate processes as they are more liable to digester souring. In addition, the in-depth understanding of the mechanism of recalcitrant dissolved organic nitrogen formation during sludge thermal pretreatment was provided.

This thesis focuses on soft sensor development based on fuzzy logic used for real time online monitoring of anaerobic digestion to improve methane output and for robust fermentation. Important process parameter indicators such as pH, biogas production, daily difference in pH and daily difference in biogas production were used to infer alkalinity, a reliable indicator of process stability. Additionally, a fuzzy logic and a rule-based controller were developed and tested with single stage anaerobic digesters operating with cow slurry and cellulose. Alkalinity predictions from the fuzzy logic algorithm were used by both controllers to regulate the organic loading rate that aimed to optimise the biogas process. The predictive performance of a software sensor determining alkalinity that was designed using fuzzy logic and subtractive clustering and was validated against multiple linear regression models that were developed (Partner N° 2, Rothamsted Research 2010) for the same purpose. More accurate alkalinity predictions were achieved by utilizing a fuzzy software sensor designed with less amount of data compared to a multiple linear regression model whose design was based on a larger database. Those models were utilised to control the organic loading rate of a twostage, semi-continuously fed stirred reactor system. Three 5l reactors without support media and three 5l reactors with different support media (burst cell reticulated polyurethane foam coarse, burst cell reticulated polyurethane foam medium and sponge) were operated with cow slurry for a period of seven weeks and twenty weeks respectively. Reactors with support media were proven to be more stable than the reactors without support media but did not exhibit higher gas productivity. Biomass support media were found to influence digester recovery positively by reducing the recovery period. Optimum process parameter ranges were identified for reactors with and without support media. Increased biogas production was found to occur when the loading rates were 3-3.5g VS/l/d and 4-5g VS/l/d respectively. Optimum pH ranges were identified between 7.1-7.3 and 6.9-7.2 for reactors with and without support media respectively, whereas all reactors became unstable at ph<6.9. Alkalinity levels for system stability appeared to be above 3500 mg/l of HCO3 - for reactors without media and 3480 mg/l of HCO3 - for reactors with support media. Biogas production was maximized when alkalinity was 3 between 3500-4500 mg/l of HCO3 - for reactors without support media and 3480- 4300 mg/l of HCO3 - for reactors with support media. Two fuzzy logic models predicting alkalinity based on the operation of the three 5l reactors with support media were developed (FIS I, FIS II). The FIS II design was based on a larger database than FIS I. FIS II performance when applied to the reactor where sponge was used as the support media was characterized by quite good MAE and bias values of 466.53 mg/l of HCO3- and an acceptable value for R2= 0.498. The NMSE was close to 0 with a value of 0.03 and a slightly higher FB= 0.154 than desired. The fuzzy system robustness was tested by adding NaHCO3 to the reactor with the burst cell reticulated polyurethane foam medium and by diluting the reactor where sponge was used as the support media with water. FIS I and FIS II were able to follow the system output closely in the first case, but not in the second. FIS II functionality as an alkalinity predictor was tested through the application on a 28l cylindrical reactor with sponge as the biomass support media treating cow manure. If data that was recorded when severe temperature fluctuations occurred (that highly impact digester performance), are excluded, FIS II performance can be characterized as good by having R2= 0.54 and MAE=Bias= 587 mg/l of HCO3-. Predicted alkalinity values followed observed alkalinity values closely during the days that followed NaHCO3 addition and water dilution. In a second experiment a rulebased and a Mamdani fuzzy logic controller were developed to regulate the organic loading rate based on alkalinity predictions from FIS II. They were tested through the operation of five 6.5l reactors with biomass support media treating cellulose. The performance indices of MAE=763.57 mg/l of HCO3-, Bias= 398.39 mg/l of HCO3-, R2= 0.38 and IA= 0.73 indicate a pretty good correlation between predicted and observed values. However, although both controllers managed to keep alkalinity within the desired levels suggested for stability (>3480 mg/l of HCO3-), the reactors did not reach a stable state suggesting that different loading rates should be applied for biogas systems treating cellulose.

Challenges surrounding energy have gained increased attention, which is not least reflected in the 2030 Agenda for Sustainable Development and the Sustainable Development Goals (SDGs). Energy issues have also become a pressing matter for most countries in the last decades. The reasons for this are not only related to the effects of the emission of greenhouse gases (GHG) from fossil fuels and their impact in climate change, but also span through other issues such as security of energy supply with geopolitical considerations and competitiveness of industry. To address these issues, a collection of public policies ranging from the international to local levels have been implemented. Sweden has historically had lower energy prices than its European counterparts, which has resulted in its industry having a relatively higher share of electricity in the total energy use by industry. The share of electricity accounts for 35% of total energy use in Swedish industry. This has led to efficiency measures being overlooked by industry, and the pulp and paper industry is by far the biggest energy user, with a share of 51% of the total energy use by industry. The variation of energy prices, and particularly electricity prices have obvious implications on the competitiveness of this sector. Production of biogas in pulp and paper mills has been gaining attention, and is now the target of an increasing number of scientific studies. The interest for this industry is not only related to security of energy supply and the environmental performance of the biogas itself, but there are also considerations regarding the biogas plant as an alternative to treat the large flows of wastewaters and other waste stream in this sector. There is an estimated biogas production potential of 1 TWh within this industry in Sweden, which accounts for 60% of the current biogas production in the country. Pulp and paper mills commonly rely on aerated biological treatment to deal with waste streams with high organic content This biological process has a high energy demand, and the integration of an anaerobic treatment, along with the use of the biogas for heat and electricity can yield a net positive energy recovery for the combined plant. This project analyses the current energy and material performance of an anaerobic biological treatment combined with an aerobic biological treatment in a recycled board mill. The anaerobic treatment is performed upstream of the aerobic one and removes most of the chemical oxygen demand of the wastewater. Energy and material balances for the plant are presented, and a comparison of the wastewater treatment plant running before and after the start-up of the biogas plant is made. The plant operation with the anaerobic digestion has shown an increased energy use of 9.4% coupled to an increased flow of wastewater of 7.7%. The average biogas production is 72 Nm³/h, which accounts for 440 kWh and is currently being flared. The introduction of AD has largely decrease the organic load in the aerobic treatment, by nearly 50%. This project ends with an optimisation model implemented with the optimisation tool reMIND to investigate potential optimisation strategies for the operation of the combined plant. The model has shown to be adequate to describe electricity use with mean error below 10%. For the biogas production, the mean error was of 16%.

Economic utilisation of biogas arising from sewage sludge is hampered by the need to remove siloxanes, which damage gas engines upon combustion. This thesis applies on-line Fourier transform infrared spectroscopy to measure siloxanes in biogas upstream and downstream of the activated carbon vessels designed to adsorb siloxanes. On-line analysis provides accurate measurement of siloxane concentrations with a detection limit below the siloxane limits set by engine manufacturers, high data intensity and timely identification of breakthrough. Cost savings of up to £0.007 kWh- 1 may be realised compared to existing grab sampling. Using on-line analysis, the performance of full-scale and bench-scale carbon vessels were measured. Full-scale carbon contactors are typically operated at Reynold’s numbers close to the boundary between the laminar and transitional regimes (Re = 40 - 55). This thesis demonstrates, at full- and bench-scale, that increasing the Reynold’s number to site the adsorption process in the transitional regime increases media capacity, by 36% in dry gas and by 400% at 80% humidity. It is postulated that the change in gas velocity profile which occurs as Reynold’s number increases reduces the resistance to siloxane transport caused by gas and water films around the carbon particles, and therefore increases the rate of the overall adsorption process. In the laminar regime (Re = 31) increasing humidity from zero to 80% led to the classical stepwise reduction in adsorption capacity observed by other researchers, caused by the increasing thickness of the water film, but in the transitional regime (Re = 73) increasing humidity had no effect as no significant water film develops. It is therefore recommended that siloxane adsorption vessels should be designed to operate at Reynold’s numbers above 55. By choosing a high aspect ratio (tall and thin) both Reynold’s number and contact time can be optimised.

The anaerobic biodegradability of food waste (FW), meat waste and FOG (fats, oils and greases) with municipal primary sewage sludge was assessed using a laboratory scale anaerobic digester and by ultimate sludge digestibility, at mesophilic conditions by varying the inoculum to feedstock ratio (1:2-1:10) and solids retention time (SRT). Preliminary analysis assessed the anaerobic digestion of food waste and meat at a biogas production over 30 days at 1000 mL and 1400 mL, respectively. The maximum methane yield was 0.18 m3/kg VS and 0.50 m3/kg VS for 1:10 in meat and FOG, respectively in 28 days with 56-61% volatile solids of destruction and first order methane generation rate of 0.15 d-1 for both meat and FOG. The optimal ratio for meat and FOG was determined to be beyond highest ratio tested (1:10), and longer SRT should be considered to investigate the impact of feedstock on methane yield. Preliminary modeling suggests that for one 1.74 MG digester, diverting just 0.6% of the food waste generated in one-third of Palm Beach County could produce enough methane to power 130-360 homes for one full month. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Neste trabalho a composição do biogás produzido em digestão anaeróbia foi avaliada em função da variação da carga aplicada específica (CAE) medida em termos da relação DQO/sólidos suspensos voláteis. Foram feitos ensaios de digestão anaeróbia utilizando vinhaça como fonte de carbono e lodo adaptado proveniente de reator UASB em 10 frascos reagentes contendo as seguintes variações de CAE: 0,20; 0,28; 0,34; 0,55; 0,95; 3,15; 6,58; 7,00; 9,60; 12,98 g.O2/g.SSV. Os melhores resultados obtidos com relação à produção volumétrica de biogás foram 263,79 mL de volume acumulado de metano para a CAE de 0,34 g.O2/g.SSV, e uma produção máxima acumulada de hidrogênio de 558,06 mL para a CAE de 6,58 g.O2/g.SSV. O resultado não se repetiu com relação ao rendimento de produção de biogás, atingindo um máximo rendimento de 80,68 LCH4/L vinhaça para a CAE de 0,20 g.O2/g.SSV, e 7,98 LH2/L vinhaça para a CAE 3,15 g.O2/g.SSV. A variação da CAE também teve influência direta na rota metabólica da digestão anaeróbia, alterando a concentração de metabólitos dissolvidos. / In this research, the composition of the biogas produced in anaerobic digestion was evaluated according to the variation of the applied load specific (ALS) measured in terms of the ratio COD/volatile suspended solids. Assays were done using anaerobic digestion of vinasse as a source of carbon and sludge obtained from UASB reactor adapted in 10 bottles for the following of ALSs: 0,20, 0,28, 0,34, 0,55, 0,95; 3,15, 6,58, 7,00, 9,60, 12,98 g.O2/g.VSS. The best results concerning to the volumetric biogas production were 263,79 ml cumulative volume of methane for ALS equal to 0,34 g.O2/g.VSS, and a maximum cumulative hydrogen production of 558,06 mL for ALS of 6,58 g.O2/g.VSS. The same was not observed with respect to yield biogas production, reaching a maximum yield of 80.68 LCH4/Lvinasse for ALS of 0,20 g.O2/g.VSS and 7,98 LH2/Lvinasse for ALS of 3,15 g.O2/g.VSS. The variation of ALS also has a direct influence on the metabolic pathway of anaerobic digestion, altering the concentration of dissolved metabolites.

Problems about greenhouse gas emissions attributed to cattle production and improvements in the productivity of these animals has been growing and becoming increasingly important. Cattle releases methane as part of their digestive process, and this represents loss of energy for the animal. The decomposition of feces releases methane and it can be recovered by digester and transformed into different types of energy. Thus, aiming to quantify the potential production of enteric methane and anaerobic fecal decomposition, as well as to evaluate ruminal and behavioral parameters of cattle fed with cottonseed and vitamin E. Six cannulated cows (864±16 kg) were distributed in a replicate 3x3 Latin square. Treatments were: 1) control diet; 2) CS: basal diet plus 30% cottonseed and 3) CSVitE: basal diet plus 30% of cottonseed plus 500 UI of vitamin E. Results were compared through orthogonal contrast and values were considered significant when P0,05. No differences were observed for dry matter intake (DMI), as well as digestibility of DM and neutral detergent fiber (NDF). Animals supplemented with cottonseed spent more time eating and ruminating and less time in idles. Reduction in the concentration and production of acetate, butyrate and the acetate: propionate ratio was observed in animals fed cottonseed compared to the control. Enteric methane mitigation was observed for the cottonseed treatments compared to the control. Changes in the substrates characteristics used to load the digesters were observed. However, no differences were verified for the total biogas production, methane yield and capacity to recover the energy of the feces in the form of methane. Inclusion of 30% cottonseed can be used as a strategy to mitigate enteric methane, without causing losses in the DMI, nutrients digestibility and anaerobic digestion of feces. In addition, it promoted favorable changes in the ingestive behavior, ruminal fermentation products, as well as in the energy partition of the gastrointestinal tract. Vitamin E when is used as antioxidant had not effect on ruminal fermentation, feeding behavior and feces anaerobic digestion, thus the inclusion is not advised due absence of positive results. / A problemática das emissões de gases de efeito estufa atribuída à produção de bovinos e melhorias na produtividade desses animais vem crescendo e se tornando cada vez mais importante. Bovinos emitem metano como parte do seu processo digestivo, e isto representa perda de energia para o animal. A decomposição das fezes gera metano, este pode ser recuperado por biodigestores e transformado em diferentes tipos de energia. Assim, objetivou-se quantificar o potencial de produção do metano entérico e da decomposição anaeróbia das fezes, bem como avaliar parâmetros ruminais e comportamentais de bovinos alimentados com caroço de algodão e vitamina E. Foram utilizadas seis vacas fistuladas não gestantes e não lactantes (876 kg±16). Os tratamentos foram: 1) Controle: dieta basal; 2) CA: dieta basal mais 30% de caroço de algodão; 3) CAVitE: dieta basal mais 30% de caroço de algodão mais 500 UI vitamina E. O delineamento experimental utilizado foi o quadrado latino. Os resultados foram comparados por contrastes ortogonais e foram considerados significantes valores de P0,05. Não foram verificadas diferenças para o consumo de matéria seca (MS), bem como digestibilidade da MS e da fibra em detergente neutro (FDN). Os animais suplementados com caroço de algodão passaram maior tempo comendo e ruminando e menor tempo em ócio. Houve redução na concentração e produção de acetato, butirato e da relação acetato:propionato dos animais que receberam caroço de algodão comparado ao controle. A inclusão do caroço de algodão provocou mitigação das emissões de metano entérico. Houve alteração nas características dos substratos utilizados para abastecer os biodigestores. No entanto, não foram verificadas diferenças para a produção total de biogás, rendimento de metano e capacidade dos biodigestores em recuperar a energia das fezes na forma de metano. A inclusão de 30% caroço de algodão pode ser utilizada como estratégia para mitigar metano entérico, sem causar perdas no consumo, digestibilidade dos alimentos e na biodigestão anaeróbia das fezes. Além disso, sua inclusão promoveu alterações favoráveis no comportamento ingestivo, nos produtos da fermentação ruminal, bem como na partição de energia do trato gastrointestinal. A vitamina E quando utilizada como antioxidante não possui efeitos sobre a fermentação ruminal, comportamento ingestivo e biodigestão anaeróbia das fezes, assim sua inclusão não é indicada devido a ausência de resultados favoráveis a sua utilização.

Research was conducted using algal biomass obtained from the surface of a secondary clarifier at Bridge City Wastewater Treatment Plant and subsequently sent through an electrochemical (EC) batch reactor at various concentrations. The first objective was to achieve maximum cell wall destruction electrochemically using the EC batch reactor and determine the optimal detention time and voltage/current relationship at which this occurred. The second objective was to subject two algal mediums to anaerobic digestion: the algal medium without electrochemical disinfection and the algal medium after disinfection. Every three days, for 12 days, total solids were measured from each apparatus to determine if cell destruction increased, decreased or did not change the consumption rate of algae by anaerobic bacteria. The consumption rate of algae is directly proportional to the production of methane, which can be used as a source of biofuel.

With an ever increasing concern for the environment, different methods of managing organic waste on dairy farms have been explored and analyzed. Anaerobic digestion has long been a popular method of managing organic waste. Its popularity stems from the potential to decrease greenhouse gases, improve air quality and provide a source of additional revenue for the farm. Problems with implementing anaerobic digestion arise from high failure rates, high start-up costs and continuous maintenance and equipment replacement. Subsidies for the initial investment and improved technology have increased the possibility of large-scale dairy farms to adopt anaerobic digestion. Due to economies of scale large-scale dairy farms are more able to adopt anaerobic digestion, but small-scale dairies struggle to finance the investment, maintain the digester system and provide sufficient organic waste to continuously feed the microorganisms inside the digester system. The increasing impact of urbanization greatly impacts the demand for anaerobic digestion on small-scale farms to mitigate the negative effects of organic waste produced by dairy farms. Dr. Conly Hansen at Utah State University suggested we use an IBR digester model to analyze the feasibility of adopting anaerobic digestion on small-scale farms. The IBR digester system is more conducive to small-scale dairies located in regions with varying temperature (i.e., Utah), and may be the solution to mitigate the negative effects of organic farm waste. Dr. Donald McMahon also suggested we analyze the potential of implementing a digester on a dairy farm that produces artisan cheese. We predicted that this would improve the feasibility due to the need to dispose of whey from the cheese production. To determine the feasibility of implementing a digester system on a small-scale dairy farm the net present value and the internal rate of return were calculated to estimate the success of the investment. These financial measures were calculated from equipment price quotes, estimations from the literature review and from using estimated annual receipts and costs for a dairy farm, artisan cheese plant and anaerobic digester system. The feasibility also depends on the success of marketing the products produced from the digester system and the farmer’s participation in incentive programs for digester systems. The products produced vary from electricity to waste disposal services, and marketing an array of diverse products and services is important to the success of the digester system. The feasibility determined by this study was estimated using generalized assumptions from various sources and should be analyzed by individual operations to determine specific farm feasibility.

Due to population expiation and the increased awareness of the impact on the environment by wastewater treatment, improved wastewater treatment systems are needed to treat municipal and agricultural wastewater. Treating wastewater with oxygen decreases carbon compounds at the expense of energy to move carbon and oxygen to be in contact with each other. Anaerobic digestion of wastewater can reduce the cost by utilizing microbes to treat high amounts of carbon in wastewater without the need for extensive oxygen requirement. With a proper balance of nutrients, microbes also produce methane, a renewable energy source. It has been suggested that microalgae be utilized to help balance the nitrogen content of wastewater for treatment by microbes. One challenge with the use of algae is the initial breakdown of algae cells. Using a digester with microorganism that can produce methane and decompose algae could enhance production of methane from the digestion of algae. The combination of wastewater, which is high in carbon content relative to nitrogen, with algae, which is high in nitrogen, could provide the balance needed for the microbes to treat wastewater and provide methane. A biomethane potential test was used to compare the ability of two microbe communities, facultative lagoon sediment and anaerobic digester sludge to digest algae. Each microbe community treated dairy, swine, municipal, and petrochemical wastewater augmented with algae and acetate. The ability to degrade augmented wastewater and produce methane was determined by measuring the volume and composition of biogas produced over time. Both treatments were successful in production of methane. Facultative lagoon sediment showed more methane produced per carbon dioxide than anaerobic digester sludge.