Biodiesel purification processes generate wastewater streams that require a large amount of energy when distillation is used as a treatment technology. Process simulation software was used to show that an alternative water treatment process involving ion exchange would require only 31% of the energy used by distillation. Experiments showed that multiple washing stages were required to meet the standard specification for sodium, an impurity present in crude biodiesel, when washing biodiesel made from used frying oil. A comparison was made between washing biodiesel in a cross-current washing configuration and a counter-current configuration. Both configurations met the specification for sodium within three washing stages; however, the counter-current configuration required less water, making it the more efficient process. Lastly, the removal of sodium from wastewater samples using an ion exchange resin was experimentally investigated. The results validated the use of ion exchange to reduce energy consumption in biodiesel purification.

Thesis (M. Sc.)--University of Western Sydney, Hawkesbury, 1991. / Includes bibliographical references.

Thesis (doctoral)--University of Lund, 1990. / "CODEN:LUTVDG/ (TVVA-90/1002)." Thesis t.p. inserted. Includes bibliographical references (p. 181-189).

Microalgae reactors, commonly known as photobioreactors, have become increasingly popular as an alternative for wastewater treatment. These systems reduce pollutants and remove nutrients such as nitrogen and phosphorous compounds from wastewater utilizing microalgae and bacteria. The biomass produced in the reactors can potentially be used to produce biofuels and decrease some of the energy demands of the process. Wastewater treating photobioreactors are a relatively new technology and many aspects of their microbiology need further study. This thesis presents a broad overview of the algal and bacterial communities present in these systems by looking at the most important species, metabolic pathways and growth dynamics of both algae and bacteria. The experiments presented in this thesis were conducted using municipal wastewater from the Västerås wastewater treatment plant. The wastewater was inoculated with algae from Lake Mälaren and compared to non-inoculated reactors. Overall, the inoculated reactors demonstrated better algal growth than those that were not inoculated. The tested systems also removed much of the ammonium and phosphorous present in the wastewater. The dominant algae in the tested systems belonged to the genera Scenedesmus, Desmodesmus and Chlorella. In addition to algae, the systems contained a large number of bacteria, mostly from the phyla Proteobacteria and Bacteroidetes. The algal photobioreactors contained a lower abundance of genes related to nitrogen metabolism, virulence and antibiotic resistance compared to the initial wastewater, showing that a shift in the bacterial community had occurred. The bacteria found in the systems were shown to be involved in synthesis of vitamins essential for algae growth such as vitamin B12, suggesting cooperation between the bacteria and algae. / I takt med att världens befolkning ökar, så produceras dagligen allt mer avfall. Detta kan orsaka stora problem för miljön. När det byggs nya system för vattenrening behöver vi även ta hänsyn till kravet att minska energiåtgången. Dagens vattenreningssystem har vissa tillkortakommanden när det gäller reningsnivåer och energianvändning. Ett alternativ till dagens system, kan vara fotobioreaktorer, dvs. vattenrening med hjälp av mikroalger. Dessa system använder mikroalger och bakterier för att rena vattnet från föroreningar, kväve och fosfor. Vattenrening med fotobioreaktorer är en relativt ny teknik. Flera aspekter gällande biologin i dessa system har ännu inte studerats i detalj. Den här avhandlingen presenterar en översikt av de alger och bakterier som är aktiva i fotobioreaktorer. Andra viktiga aspekter som tillväxt, arter samt vattenreningsförmåga har också studerats. Ett antal försök genomfördes där alger från Mälaren tillsattes i vatten från Västerås kommunala vattenreningsanläggning. Storleken på försöken varierade mellan 250 ml och 20 liter. Det visade sig att algerna hade en bra tillväxt samt att mängden ammonium och fosfor minskade i vattnet under försöksperioden. De alger som tillväxte mest i studien tillhörde Scenedesmus, Desmodesmus och Chlorella. Förutom alger tillväxte även ett stort antal bakterier från grupperna Proteobacteria and Bacteroidetes. Dessa bakterier visade sig syntetisera viktiga vitaminer, t.ex. vitamin B12, som algerna normalt inte kan syntetisera själva. Sammanfattningsvis, så presenterar denna avhandling viktig information gällande alger och bakterier i en fotobioreaktor. Informationen kan vara ett viktigt bidrag till framtida utveckling av storskaliga fotobioreaktorer för vattenrening.

Biodiesel purification processes generate wastewater streams that require a large amount of energy when distillation is used as a treatment technology. Process simulation software was used to show that an alternative water treatment process involving ion exchange would require only 31% of the energy used by distillation. Experiments showed that multiple washing stages were required to meet the standard specification for sodium, an impurity present in crude biodiesel, when washing biodiesel made from used frying oil. A comparison was made between washing biodiesel in a cross-current washing configuration and a counter-current configuration. Both configurations met the specification for sodium within three washing stages; however, the counter-current configuration required less water, making it the more efficient process. Lastly, the removal of sodium from wastewater samples using an ion exchange resin was experimentally investigated. The results validated the use of ion exchange to reduce energy consumption in biodiesel purification.

Microconstituents (MCs) have become an emerging concern to scientists and researchers. Due to the development of analytical technology, it is now possible to study MCs at ηg/L to μg/L levels. Wastewater treatment plants (WWTPs) are the major point source for MCs entering the environment based on the literature. WWTPs are known to be unable to remove many MCs to a safe level. In order to fully understand the fate of MCs in WWTPs and to further improve the design of WWTPs in terms of MC removal, it is necessary to examine removal mechanisms such as sorption and biodegradation in WWTPs. Three MCs, bisphenol A (BPA), 17-α-ethinylestradiol (EE2) and triclosan (TCS), were chosen for this study. They are chemicals reported to be hydrophobic and have low vapor pressure, which makes sorption a highly potential removal mechanism. Primary sludge and activated sludge (AS) were used to perform sorption kinetics and isotherm experiments for BPA, EE2 and TCS. Primary sludge was collected from local WWTPs, and AS was generated from a lab-scale continuous flow bioreactor system maintained at solids retention times of 15, 10 and 5 d and hydraulic retention time (HRT) of 6 h. Alum was added to synthetic wastewater influent at concentrations typically used for phosphorus removal at some plants. Alum has the potential to change sludge structure and influence the sorption process. A comparison was made with AS as the adsorbent with and without alum addition to the AS to study the influence of alum on the sorption processes. The selected MCs were found to reach sorption equilibrium with primary sludge within 7 h. A pseudo second-order kinetic model was an excellent fit to describe the sorption processes of selected MCs. The solids-liquid partitioning coefficient (Kd) was determined for the three chosen MCs. The Kd values found for primary sludge and AS are very close. The Kd for MCs sorbed to AS in this study were compared with the Kd for AS without alum addition. Although alum addition showed no influence on effluent soluble chemical oxygen demand, it decreases the Kd for BPA and EE2 sorbed to AS. In contrast, a much higher Kd for TCS was observed for AS with alum addition. Judging from the R2 values, the linear sorption model is not suitable for some of the isotherms. Langmuir and Freundlich sorption isotherms were further used to fit the experimental data by applying linear regression and nonlinear regression approaches. The Freundlich isotherm was found to be the most suitable model to describe the experiment data.

There is an increasing need for tertiary level wastewater treatment in Canada, driven in some cases by both provincial and federal regulation (Canada Gazette, 2012). Tertiary nitrification is the biologically mediated oxidation of nitrogen in the form of ammonia to nitrate following secondary treatment of carbonaceous material (Barnes & Bliss, 1983). The application of tertiary nitrification can prove challenging in the Canadian climate because of the temperature sensitive nature of nitrifiers (Hwang & Oleszkiewicz, 2007). Hence the greater than 1000 lagoon treatment plants currently in operation throughout country are susceptible to the full onslaught of weather effects and as such their nitrification processes become non-existent during the winter months (Delatolla et al., 2011,Hoang et al., 2014). The moving bed biofilm reactor (MBBR) system has been studied and shows promise for continuous nitrification with prolonged exposure to cold temperatures (Hoang et al., 2014). They are marketed as cost effective and low operation intensive upgrade options for existing treatment plants as well as effective stand-alone systems and are currently in operation in many countries worldwide (WEF, 2011). Despite the MBBRs initial development as a nitrification technology, recent research has been focused on COD removal systems. Studies showing that MBBR performance is directly related to surface area loading rates (SALRs) and not carrier type or shape have been performed exclusively on COD removal systems. The influence of MBBR carrier type on system solids production has also been solely studied for COD removal and the principles learnt have been transferred to tertiary nitrification systems without confirmation that they hold true. There is an absence of research on tertiary nitrifying kinetics; the effect of loading and carrier type, the nature of the solids produced and the carrier biofilm characteristics. This study investigated three MBBR carrier types, the K3, M and P Anoxkaldnes carriers in an effort to quantify the effects of carrier type on nitrifying kinetics, biologically – produced solids and the bacterial community at normal and high loading conditions. Four tertiary nitrifying laboratory scale MBBRs were fed with synthetic wastewater and operated at a high loading condition (HLC) with a SALR of 1.89 ± 0.10 g-N/m2•d and a normal loading condition (NLC) with SALR of 0.91 ± 0.1 g-N/m2•d. At both HLC and NLC, results show no difference in the ammonia removal rates obtained by the different carrier types. It was however noticed that stressed operational conditions developed for the P and M carrier at the HLC due to the clogging of carrier pore spaces with biofilm and subsequent reductions in removal efficiency were observed. Despite the fact that larger surface area to volume carriers (such as the M and P) may lead to MBBR designs with smaller footprints and lower operational cost, the study revealed their greater propensity to become clogged under high loading conditions than the smaller surface area carriers (such as the K3 ). In addition the larger surface area carriers demonstrated longer transitional periods from high loading conditions to lower loading conditions. A reduction in effluent total suspended solids (TSS) concentrations and improved solids settleability was observed with the shift from HLC to NLC. These results suggest the avoidance of high loading conditions in tertiary nitrifying MBBR operation. If low loading rates are not achievable then system design may have to consider the incorporation of coagulant use or an advanced solids separation technique to meet effluent solids regulation. Variable pressure scanning electron microscope (VPSEM) images at HLC showed the presence of water mites on the K3 carrier and nematodes and ciliates on the M and P carriers. While NLC images do not show these organisms. VPSEM also measured thicker biofilms during the HLC than the NLC for all carriers. The results demonstrate a difference in the meso-environments and suggest a difference in the micro-environments of the biofilm attached to each carrier. Microbial analysis showed no shifts in the dominant nitrifying species between the loading conditions, as well as no differences in the percent live /dead cell coverage. Nitrosomonas and Nitrospira were identified as the dominant AOB and NOB genera respectively at both the HLC and the NLC. Clear shifts in the microbial populations were observed for specific bacteria; with filamentous bacteria being observed at greater relative abundance at HLC than HLC. The increased relative abundance of filamentous organisms are also associated with the significantly poorer effluent settling characteristics observed at HLC.

Lower production rate of solids in attached growth moving bed bioreactor (MBBR) systems as compared to conventional activated sludge (AS) systems makes them an attractive choice for municipal wastewater treatment (Ødergaard et al. 1994). However, the production of biologically-produced solids in MBBR systems is currently not well defined and requires additional investigation. Three identical MBBR reactors were operated under the same dissolved oxygen (DO) concentration, influent pH and volume of Anoxkalnes media in two different experimental phases. In the first phase, the hydraulic retention time (HRT) kept constant in three reactors and SALR increased and in the second phase, the SALR was the constant parameter while HRT increased. These two phases were implemented to investigate the effect of variations in HRT and SALR on biologically-produced solids in MBBR reactors. This study demonstrated that HRT and SALR play an important role in settling characteristics of the biologically-produced solids in MBBR systems.

Abstract This dissertation describes a study of the treatment of wastewater using the flocculation process. Wastewater samples from Barloworld Plascon paints were used for the research. Environmental pressure has necessitated the introduction of a new generation of low-solvent paints. The behaviour of these in coagulation and flocculation treatment processes has not been investigated previously. The optimum flocculent dosage for these paints was investigated. It was found that for paint wastewater to be flocculated, the effect of the dispersants needs to be counteracted, which destabilizes the colloidal suspension, enabling flocculation and settling to occur. Results showed a correlation between the solid content of wastewater and flocculent dosage. Changes in redox potential have been found to be associated with good flocculation. In this work, redox potential was evaluated as an indicator for destabilisation of the dispersants. It was shown that redox potential can be used as an indicator of good flocculation at low dispersant concentrations. Owing to the importance of the hydrolysis reactions of Al3+ in flocculation, which are affected by pH, the pH range in which good flocculation occurs was determined. Results show that optimal flocculation occurred between pH 4 and 5. A strong relationship between flocculent dosage and particle nucleation and growth was observed. Results also showed that mixing improves flocculation kinetics.

There is a significant need to remove ammonia from municipal wastewater to meet increasingly stringent regulations set by Canada, US, and Europe. Although existing conventional biological wastewater treatment technologies are shown to achieve effective ammonia treatment, they are substantially limited by increased operational intensity and cost. Due to these limitations, other cost-effective biological treatment technologies, such as partial nitritation/anammox (PN/A), have become a more attractive solution for nitrogen removal at wastewater resource recovery facilities (WRRF). A moving bed biofilm reactor system (MBBR) operating under a novel design strategy using elevated total ammonia nitrogen (TAN) loading rate has shown promise to achieve robust partial nitritation and the oxidation of TAN with limited oxidation of nitrite without the need for intense operational measures. However, the novel and promising design strategy using elevated TAN loading rate was applied at higher influent TAN concentrations that are typically greater than concentrations in mainstream municipal wastewater. Therefore, the objective of this dissertation is to investigate and optimize the design and performance of a promising elevated loaded partial nitritation MBBR technology for mainstream, municipal wastewater treatment followed by downstream anammox to complete the design of a robust, stable, energy-efficient, and low operational cost total nitrogen removal PN/A system for mainstream wastewaters. The first specific objective of the dissertation is to isolate the optimal design parameter of a mainstream elevated loaded partial nitritation MBBR system. The results identifies optimal distinct elevated surface area loading rate (SALR), hydraulic retention time (HRT), and airflow rate that achieve stable partial nitritation performance (i.e., optimum total ammonia nitrogen (TAN) removal kinetics and percent NOₓ as nitrite) in a mainstream elevated loaded partial nitritation MBBR system. The study shows that TAN SALR, HRT, and airflow rate significantly affect TAN surface area removal rates (SARR) and percent NOₓ as nitrite and, as such, identifies the optimal design parameters (TAN SALR, HRT and airflow rate) of a mainstream elevated loaded partial nitritation MBBR system. A TAN SALR of 5 g TAN/m²∙d, HRT of 2h and airflow rate of 1.5 L/min are identified to provide stable partial nitritation performance with a TAN SARR of 2.3 ± 0.3 g TAN/m²∙d and a percent of NOx as nitrite of 84.8 ± 1.2% in the mainstream elevated loaded partial nitritation MBBR system. The second specific objective further identifies a new design configuration and the mechanism of nitrite oxidation suppression of the mainstream elevated loaded partial nitritation MBBR technology. The results identifies a unique design strategy using an elevated TAN SALR of 5 g TAN/m²∙d to achieve cost-effective, stable, and elevated rates of partial nitritation in an MBBR system under mainstream conditions. The elevated loaded partial nitritation MBBR system achieves a TAN SARR of 2.01 ± 0.1 g TAN/m²∙d and NO₂⁻-N:NH₄⁺-N stoichiometric ratio of 1.15:1, which is appropriate for downstream anammox treatment. The elevated TAN SALR design strategy promotes nitrite-oxidizing bacteria (NOB) activity suppression rather than a reduction in NOB population as the reason for the suppression of nitrite oxidation in the mainstream elevated loaded partial nitritation MBBR system. NOB activity is limited at an elevated TAN SALR, likely due to thick biofilm embedding the NOB population and competition for dissolved oxygen (DO) with ammonia-oxidizing bacteria for TAN oxidation to nitrite within the biofilm structure, which ultimately limits the uptake of DO by NOB in the system. The third specific objective of this research characterizes the effects of distinct mixing and aeration strategies on the performance of the mainstream elevated loaded partial nitritation MBBR technology. This is addressed through a study investigating and comparing the kinetics, biofilm characteristics, and embedded biomass of three distinct mixing and aeration strategies employed to operate the mainstream elevated loaded partial nitritation MBBR system. The study compares the conventional mixing and aeration condition, continuous aeration with mechanical paddle & aeration, and recirculation pump & aeration utilized to optimize the partial nitritation MBBR system to achieve low DO effluent concentrations for optimal downstream anammox treatment. The results show that maintaining mixing and aeration in the elevated loaded partial nitritation MBBR system with recirculation pump & reduced aeration achieves lower effluent DO concentration and stable partial nitritation with appropriate NO₂⁻-N:NH₄⁺-N stoichiometry ratio of 1.09:1 for subsequent anammox treatment compared to operation with continuous aeration or mechanical paddle & aeration. The fourth specific objective of this research investigates the promising elevated loaded PN/A configured system for nitrogen removal under mainstream conditions. This is achieved through the operation of the elevated loaded partial nitritation MBBR system following the anammox unit as a combined two-stage system for nitrogen removal at mainstream municipal concentration. The elevated loaded partial nitritation MBBR system provides optimal NH₄⁺-N:NO₂⁻-N stoichiometric effluent ratio of 1:1.17, resulting in the successful operation of a downstream anammox unit with a total nitrogen removal rate at 0.22 ± 0.2 g N/m²/d and total nitrogen removal efficiency at 74.1 ± 0.7%. The average NO₂⁻-N to NH₄⁺-N molar removal ratio is 1.05 ± 0.1 from the anammox unit. Also, the anammox bacteria (AnAOB) gene copies are at 3.28 ± 0.7 × 10⁸, a value significantly higher than the AOB and NOB gene copies at 9.17 ± 1.1 × 10⁴ and 6.23 ± 1.0, respectively. This confirms that anammox activity is established and nitrogen removal is primarily through the anammox process. The results and overall system performance demonstrate that the combined two-stage mainstream elevated loaded partial nitritation/anammox MBBR system has shown promise and offers great insights for further advancement of the anammox process at mainstream municipal wastewaters. Finally, the economic evaluation and cost comparative analyses conducted show that compared to the conventional biological nitrification/denitrification process for nitrogen removal, the two-stage elevated loaded PN/A system offers a 57.6% savings on energy cost, 100% savings on chemical cost, and 68.7% savings on the cost of sludge disposal. Therefore, the two-stage elevated loaded PN/A system, in addition to high nitrogen removal efficiency, reduced footprint, and ease of operation, is also economically favorable and reduces the overall operational cost of wastewater treatment system by 61.6%, thus saving up to an average of 3.7 million CAD every year.