Deflocculation is a common upset event in biological wastewater treatment plants and causes significant problems in biosolids discharge and environmental management. However, fundamental understanding of deflocculation is limited. The overall objective of this work was to explore the fundamentals for deflocculation under transients of short-term low dissolved oxygen (DO). The investigation was carried out in a sequence of batch and continuous experiments on activated sludge, followed by batch experiments on E. coli suspensions. Both batch and continuous experiments on activated sludge demonstrated deflocculation of bioflocs under the transients of low DO (< 0.5 mg/L). Under the short-term low DO (in hours), turbidity increased by 20 times in the batch system and by 1-2 times in the continuous system, concentrations of suspended solids increased by 1-2 times, number of small particles (< 12.5 mm) increased by 2 times, more soluble EPS (proteins and humic substances) were released into supernatant or treated effluents, the removal efficiency of organic compounds was reduced by 50-70%. A 40% of increase in bulk K+ but a 30% of decrease in bulk Ca2+ under the DO limitation were observed in the batch experiments. There were significant increases in bulk K+ and decreases in bulk Ca2+ in the continuous experiments. Reversible changes were observed within 24 hours once the DO stress was removed. Floc strength of the remaining bioflocs after deflocculation increased. Deflocculation under the short-term low DO was consistent with an erosion process. The addition of selected chemicals (i.e., Ca2+, tetraethylammonium chloride, glibenclamide, and valinomycin) did not prevent deflocculation under the short-term low DO. It is proposed that a DO stress causes an efflux of cellular K+ but an influx of extracellular Ca2+, resulting in a decreasing ratio of Ca2+/K+ in extracellular solution and thereby causing deflocculation. The E. coli tests supported that increasing bulk K+ under the DO limit was due to the release of cellular K+ and was a stress response to the DO limitation.

No description available.

No description available.

In order to encourage the establishment of an erosion controlling vegetative ground cover, low cost organic amendments and inorganic fertilizers were incorporated into an abandoned, non-acid generating mine tailings pond. By amending these gold mine tailings with a small quantity (3.7 kg m-2) of combined papermill sludge and fertilizer, a consistent and robust grass/Medicago sativa sward was established within the first growing season. This tailings amendment and the subsequent plant establishment lead to improvements in substrate fertility characteristics including aggregation, bulk density, as well as cation exchange capacity and organic content. Chemical fertility (available nitrogen and phosphorous) was ameliorated by all initial amendment treatments. However, the effect was relatively short-lived, with all amendment treatments returning to their background levels of these nutrients within one to two years. This study further proves the usefulness of papermill sludge as a low cost amendment for disturbed soil substrates, including mine tailings.

Deflocculation is a common upset event in biological wastewater treatment plants and causes significant problems in biosolids discharge and environmental management. However, fundamental understanding of deflocculation is limited. The overall objective of this work was to explore the fundamentals for deflocculation under transients of short-term low dissolved oxygen (DO). The investigation was carried out in a sequence of batch and continuous experiments on activated sludge, followed by batch experiments on E. coli suspensions. Both batch and continuous experiments on activated sludge demonstrated deflocculation of bioflocs under the transients of low DO (< 0.5 mg/L). Under the short-term low DO (in hours), turbidity increased by 20 times in the batch system and by 1-2 times in the continuous system, concentrations of suspended solids increased by 1-2 times, number of small particles (< 12.5 mm) increased by 2 times, more soluble EPS (proteins and humic substances) were released into supernatant or treated effluents, the removal efficiency of organic compounds was reduced by 50-70%. A 40% of increase in bulk K+ but a 30% of decrease in bulk Ca2+ under the DO limitation were observed in the batch experiments. There were significant increases in bulk K+ and decreases in bulk Ca2+ in the continuous experiments. Reversible changes were observed within 24 hours once the DO stress was removed. Floc strength of the remaining bioflocs after deflocculation increased. Deflocculation under the short-term low DO was consistent with an erosion process. The addition of selected chemicals (i.e., Ca2+, tetraethylammonium chloride, glibenclamide, and valinomycin) did not prevent deflocculation under the short-term low DO. It is proposed that a DO stress causes an efflux of cellular K+ but an influx of extracellular Ca2+, resulting in a decreasing ratio of Ca2+/K+ in extracellular solution and thereby causing deflocculation. The E. coli tests supported that increasing bulk K+ under the DO limit was due to the release of cellular K+ and was a stress response to the DO limitation.

Filamentous bulking is a problem that has long plagued activated sludge (AS) wastewater treatment plants (WWTPs). Much research has looked at its prevention and control but there is still no solution. The sludge microbiological community is very complex and there are many factors that can affect bulking. Clay addition in scaled-down activated sludge systems was investigated at concentrations of 0.4, 2.0 and 5.0 g/L along with sequencing batch reactor (SBR) parameters when run with a synthetic wastewater (SWW). The 5.0g/L concentration exhibited positive results on settling in the form of modified SVI but appeared to cause no reduction in filament length. These preliminary investigations indicate that clay may help improve sludge settling but make no difference in the abundance of filamentous microorganisms. The SBRs exhibited trends in regards to running systems with a synthetic wastewater. A loss of volatile suspended solids (VSS), coupled with increase in sludge volume index (SVI), suggested a link between lack of non-VSS and settling ability. This has implications in the importance of non-VSS such as grit or clay in research performed using SWWs.

Effective use of resources is essential in the development towards a sustainable industry. Waste products, such as sludge from industrial waste water treatment, often contain valuable reserves of plant nutrients but this resource is nonetheless commonly disposed of as contaminated waste.  Approximately 1 500 ton phosphorus per year is added in biological waste water treatment at the Swedish pulp and paper industries and this non-renewable resource thereby ends up in their so called biosludge. The most common way to discard the sludge is by incineration. Besides the high levels of phosphorus, the biosludge usually contains high levels of moisture and ash forming elements, sulfur and chlorine, which makes it a rather problematic fuel. The aim with this study was to investigate different aspects on ash transformation chemistry during co-combustion of biosludge, from the pulp and paper mill SCA Packaging Obbola AB, with wood fuels and wheat straw. The phosphorus recovery potential, and the effects on deposit formation and emissions,  were examined by SEM-EDS- and XRD-analysis of ash from co-combustion experiments. The experimental results were complemented with theoretical analysis based on thermochemical equilibrium calculations. The biosludge from SCA Obbola contained high levels of Ca which had a large impact on the ash transformation reactions. Most of the phosphorus from the fuels stayed in the solid ash during combustion, and in all ash assortments, except for the pure wood fuel, it was primarily found in the crystalline structure whitlockite, Ca9(K,Mg,Fe)(PO4)7. Hydroxyapatite, Ca5(PO4)3OH, was identified in ash from combustion of the pure wood fuel and wheat straw, and in the mixture of biosludge and wood fuels with the lowest proportion of sludge. Of the two phosphorus compounds, hydroxyapatite is more difficult to break down. It is therefore promising from a phosphorus recovery perspective that whitlockite was the main phosphorus compound in most of the ash assortments. Some of the sulfur in the sludge reacted with Ca and formed solid CaSO4, which stayed in solid ash during combustion, while chlorine generally left the bottom ash by volatilization. K- and Si-rich agricultural residues, such as wheat straw, are associated with a number of ash-related problems, including deposit formation due to low ash-melting points. During co-combustion of biosludge and wheat straw, the melting tendencies of the wheat straw ash elements were examined. According to the thermochemical equilibrium calculations, the composition of the mixed fuels would result in a significantly higher initial slag formation temperature compared to the pure wheat straw. This trend was also observed in the experimental results. It is likely that the relatively high levels of Ca, Al and P in the sludge all contributed to reduced slag formation in the wheat straw ash, by formation of ash compounds with higher melting temperatures. The high calcium levels may however have reduced some of the positive effects of increased P and Al contents by these elements preferably reacting with Ca instead of capturing alkali in crystalline structures.

Short-term sludge fermentation was explored as a means of solubilizing phosphorus from different types of undigested sludge to facilitate nutrient recovery and generate volatile fatty acids (VFA) for enhanced nutrient removal. Phosphorus solubilization and VFA production was compared from the fermentation of primary sludge (PS), waste activated sludge (WAS), and from co-fermenting primary and waste activated sludge from wastewater treatment plants that do not practice biological nutrient removal. Co-fermented sludge resulted in the best combination of nutrient release and VFA production compared to separate fermentation of PS and WAS. After 4 days of fermentation, co-fermented sludge contained 48% of TP as dissolved phosphorus, and produced 1624 mg l-1 of VFA-COD which corresponds to a VFA-COD production rate of 0.139 mg mg-1 VS. In terms of total sludge management, co-fermentation resulted in greater overall VFA production and phosphorus solubilization than individual sludge fermentation.

Xenobiotic Organic Compounds (XOCs) are present in wastewater and wastewater-impacted environmental systems. Pharmaceuticals and personal care products are a broad and varied category of chemicals that are included among these compounds. Although, these compounds have been detected at low levels in surface water, concerns that these compounds may have an impact on human health and aquatic life, have led to increased interest in how XOCs are removed during wastewater treatment. Recognizing specific mechanisms in recent literature and simulating those mechanisms responsible for the removal of XOCs is the main objective of this study. Conventional models, such as the popular activated sludge models (ASM1, ASM2, etc), do not sufficiently address the removal processes; therefore, a fate model is created to provide a means of predicting and simulating removal mechanisms along with experimental analyses. GPS-X is a multi-purpose modeling tool for the simulation of municipal and industrial wastewater treatment plants. This software package includes conventional models as built-in libraries, which can be used as bases on which new models can be created. In this thesis, the removal mechanisms of XOCs are recognized and investigated; a new library for GPS-X is also created to include XOCs. As a first step the uncalibrated fate model, which includes all mechanisms of interest with their process rates and state variables, is developed using in GPS-X software. A modified ASM1 (Mantis model) is used as a basis for developing the fate model. Since only a group of mechanisms is responsible for the removal of each compound the mechanisms are categorized in three different case studies as the next step. Thus, one submodel is associated with each case study. The model developer toolbar in GPS-X software is used to develop the model for these case studies. The first case study involves the removal of antibiotics, such as Sulfamethoxazole. The removal mechanisms used in this case are biodegradation, sorption, and parent compound formation, with co-metabolism and competitive inhibition effects being inserted into the structure of the model. Secondly, the removal of nonylphenol ethoxylates (NPEOs) occurs through abiotic oxidative cleavage, hydrolysis, and biodegradation. The third case study includes removal mechanisms of biodegradation and sorption for neutral and ionized compounds. In the calibration process, model parameters are tuned such that the model can best simulate the experimental data using optimization methods. A common error criterion is Sum of Squared Errors (SSE) between the simulated results and the measured data. By minimizing SSE, optimal values of parameters of interest can be estimated. In each case study different data sets were used for the validation process. To validate the calibrated model, simulated results are compared against experimental data in each case study. The experimental data set used in the validation process is different from that used for calibrating the model, which means the validation process data set was obtained from the different literature. By looking at the validation results, it is concluded that the proposed model successfully simulates removal of XOCs. Since the operating parameters of wastewater treatment plants, such as Solids Retention Time (SRT) and Hydraulic Retention Time (HRT) are crucial for the fate of XOC???s, a sensitivity analysis is carried out to investigate the effect of those parameters. Moreover, the pH effect is studied because it relates to the ionized XOCs. Sensitivity analysis results show that the fate model is more sensitive to model parameters i.e. biodegradation rate constant (kb) than the operational parameters, i.e. SRT and HRT. Furthermore, the responses showed sensitivity to pH, whereby acidic conditions provide a better environment for removing neutral forms and alkaline conditions were suitable for removing ionized forms, according to the ionized compound fate model.

Based on a diverse consortia of research completed within the last 15 years, it has been found that Pharmaceutical Compounds (PCs) are present in detectable levels within a variety of environmental matrices, including tap water. This is largely attributed to anthropogenic activities as humans are the majority consumer of PCs. As a result, the primary method of disposal is via wastewater pathways resulting from human excretion of ingested PCs. Based on past research into PC fate via the wastewater treatment process, only limited biotic and abiotic transformations are achieved – most PC’s are detected in the effluents of WWTP’s. This suggests that improving the removal of PCs during the wastewater treatment process provides a promising strategy for limiting the conveyance of PCs to the environment. Historically, studies regarding PC fate in WWTPs have predominantly focused on the activated sludge process. However, fixed film (biofilm) wastewater treatment technologies continue to gain popularity at full scale wastewater treatment facilities. The limited studies which investigated fixed film wastewater treatment processes have reported that improved transformation efficiencies were observed relative to activated sludge systems. Based on these previous studies, it was postulated that the more diverse bacterial consortium present within the Integrated Fixed Film Activated Sludge (IFAS) process, a novel treatment process which has recently gained popularity in North America, may lead to improved transformation efficiencies (“removals”) of these very complex compounds. Only one previous study which investigated the transformation efficiencies of the IFAS process compared to a control was found. It was therefore considered that an additional investigation into the IFAS process warrants further investigation. Four IFAS Sequencing Batch Biofilm Reactors (SBBRs) and four control Sequencing Batch Reactors (SBRs) were operated with varied experimental conditions in a 22 factorial design to investigate whether an observable difference in the level of PC transformations would result via the IFAS process when compared to a control. Experimental conditions were characterized by varying the operating Solids Retention Time (SRT) and mixed liquor temperature. For all other operational parameters, best efforts were made to ensure both reactors were operated under equivalent conditions. This permitted a true assessment of the effects of the inclusion of IFAS media. Reactors were investigated through three phases of sampling, under which the performance of the reactors was investigated through the measurement of the following parameters: • Conventional parameters (tCOD, sCOD, TAN, NO3-N) within the initial and final samples; • Operational parameters (MLSS, MLVSS, ESS); and • The transformation efficiencies achieved for 5 PC (Carbamazepine, Sulfamethoxazole, Trimethoprim, Atenolol and Acetaminophen). During all three phases of PC sampling, the pilot reactors were found to have been performing as anticipated with respect to conventional contaminant removals. Organic removals were found to be statistically similar between the IFAS and control reactors across all four experimental conditions. Full nitrification was observed for all reactors with the exception of the control SBR operated under the low SRT, low temperature condition. The IFAS SBBRs were found to demonstrate improved nitrification kinetics when compared to their respective controls operated under the same experimental conditions. This was believed to be related to the more diverse bacterial consortia present as a result of the IFAS biofilms. All reactors were generally believed to be operating at steady state and were within an acceptable range of the target operating conditions. Due to complications associated with the analysis of samples, only CBZ, TRIM, ATEN and ACE could be successfully quantitated. CBZ was found to not have been transformed to any appreciable level across all conditions investigated through either the IFAS SBBRs or control SBRs. ACE was transformed at efficiencies greater than 99% under all conditions and in both IFAS and control reactors and therefore no comparison could be made. TRIM and ATEN demonstrated improved transformation efficiencies under all conditions within the IFAS reactors. The presence of IFAS media, SRT and temperature were all found to be statistically significant effects through ANOVA using a confidence limit of 95%.