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There is a growing awareness of the valuable nutrients (nitrogen and phosphorus) being lost in conventional wastewater treatment systems. Although the removal of these nutrients has been well addressed, efforts for nutrient recovery have seen little development. As the emphasis on sustainability in the wastewater treatment industry increases, conventional wastewater treatment processes are being re-evaluated and new treatment systems developed. A possible nutrient recovery mechanism is the precipitation of magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O), commonly known as struvite. Human urine has been identified as a rich source of nutrients in wastewater; hence the separate collection of urine is considered a viable method of enabling struvite recovery. Since dilution of urine to a certain degree is inevitable, reconcentration of urine beyond the solubility limit of struvite is critical. Currently available methods for reconcentration (e.g., evaporation, freeze-thaw, reverse osmosis and electrodialysis) are relatively expensive with high energy demand. Thus, the research here aims to demonstrate nutrient reconcentration from diluted urine and simultaneous organic removal by using the principles of microbial desalination cells (MDCs), where energy released from organic oxidation is partially used for the separation of nutrient ions. With reduced energy demand, a sustainable method for the utilization of source-separated urine is examined. The performance of bioelectrochemical systems relies on the activity of exoelectrogenic bacteria to transfer electrons to the anode. An examination of exoelectrogen sensitivity at various wastewater treatment conditions (i.e. ammonia and oxygen) is an important component of this research. Methanogenesis is considered the greatest challenge in achieving practical applications in anaerobic bioelectrochemical systems. An electrolytic oxygen production method is suggested for effective control of methanogenesis in a feasible and cost-effective manner. / Thesis / Master of Applied Science (MASc)

No / Extracting waterborne contaminants to ozone-loaded Volasil¿245 (a siloxane solvent in which ozone is ten times more soluble than water) has been studied as a means of enhancing reaction kinetics and thus, providing more rapid wastewater decontamination. Investigation was carried out with respect to 2-chlorophenol and dichloromethane. Using a pilot scale continuous flow liquid¿liquid/ozone water treatment system, 2-chlorophenol was extracted to the ozone-loaded solvent phase and considerable extents of destruction were achieved. However, the approach was demonstrated to yield slightly less destruction than direct gas contact for the same utilization of ozone and enhanced reaction kinetics were not shown to occur. This was suggested to be due to increased interfacial mass transfer resistance and/or the promotion of less destructive reaction pathways. Modification of the existing pilot system, by conversion from co- to counter-current solvent-loading, enabled greater dissolved ozone concentrations to be achieved within the solvent. Increasing the counter-current exchange column height to not, vert, similar2.5 m was suggested for achieving a near optimum level of performance. The liquid¿liquid/ozone approach was demonstrated to be an effective means of indirectly exposing wastewater contaminants to concentrated ozone. As such the technology may be applicable as an alternative to direct gas contact in instances where the avoidance of contaminant sparging is desired (i.e. where contaminants are highly volatile, pungent and/or toxic) or foaming occurs

Yes / This study investigated adsorption kinetics, adsorption equilibrium, and adsorption isotherm of three dyes [i.e., methylene blue (MB), rhodamine-B (RB), and safranin T (ST)] onto polyacrylonitrile (PAN) and ethanolamine (EA) grafted PAN nanofibers (NFs) membranes (EA-g-PAN). The membranes were characterized by field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR) spectroscopy, and Brunauer–Emmet–Teller (BET). FE-SEM showed a smooth morphology for the NFs before and after grafting, while FT-IR confirmed EA grafting into the nitrile group of PAN. The grafting percentage with no change in the physical nature of the membrane was 12.18%. The nitrogen adsorption–desorption isotherms for PAN and EA-g-PAN NFs membranes were similar and classified as a Type IV according to the International Union of Pure and Applied Chemistry. The surface area, pore-volume, and pore size of the EA-g-PAN increased to 21.36 m2 g−1, 0.16 cm3 g−1, and 304.93 Å, respectively. The pores were cylindrical mesopores with bimodal openings, which means that pores were open at both ends. The adsorption of the MB, RB, and ST dyes onto the PAN and EA-g-PAN NFs membranes leveled off at ~ 60 min. The adsorption kinetics showed good fitting to pseudo-second-order kinetic model and multi-step diffusion process. The order of the dye adsorption was PAN / the Deanship of Scientific Research, King Saud University [RG-1440-060]

Effective wastewater treatment is needed to reduce the water pollution problem. However, massive energy is consumed in wastewater treatment, required to design an innovative system to reduce the energy consumption to solve the energy crisis. Integrated photobioelectrochemical system (IPB) is a powerful system to combine microbial fuel cells (MFCs) and algal bioreactor together. This system has good performance on the organic degradation, removal of nitrogen and phosphorus, and recover the bioenergy via electricity generation and algal harvesting. This dissertation is divided to twelve chapters, about various aspects of the working mechanisms and actual application of IPB. Chapter 1 generally introduces the working mechanisms of MFCs, algal bioreactor, and modeling. Chapter 2 demonstrates the improvement of cathode material to improve the structure and catalytic performance to improve the MFC performance. Chapter 3 describes the process to use microbial electrolysis cell (MEC) to generate biohythane for the energy recovery. Chapters 4 and 5 demonstrate the application of stable isotope probing to study Shewanella oneidensis MR-1 in the MFCs. Chapters 6 to 8 describe the application of models to optimize MFC and IPB system performance. Chapter 9 describes the strategy improvement for the algal harvesting in IPB. Chapter 10 describes the application of scale-up bioelectrochemical systems on the long-term wastewater treatment. Chapter 11 finally concludes the perspectives of IPBs in the wastewater treatment and energy recovery. This dissertation comprehensively introduces IPB systems in the energy recovery and sustainable wastewater treatment in the future. / Ph. D. / The resource of pure water becomes more and more valuable, and the large discharge of the wastewater into the environment would even cause the environmental pollution. Thus, the wastewater is a necessary method to remove the organics out of the wastewater. However, the large energy consumption is a critical issue to solve due to the global energy burden. How to reduce the energy consumption in the wastewater treatment is the required step to achieve the sustainable water treatment. Integrated photobioelectrochemical system (IPB) is a new promising technology, alternative to the traditional wastewater treatment techniques (e.g., anaerobic digester or activated sludge reactor) with low energy consumption. The IPB system was to combine microbial fuel cells (MFCs), which is a typical bioelectrochemical system (BES), and the algal bioreactor together, to achieve the performance on the organic degradation, removal of nitrogen and phosphorus in the wastewater, and recover the bioenergy via electricity generation and algal harvesting. The system was proved to be effective, but most of the IPB systems were only proved to work in the laboratories, and there is still a large potential space to improve the IPB system performance in the actual environment. Herein, this dissertation combines multiple studies about the IPB improvement and scaled-up process in the real wastewater treatment. Chapter 1 generally introduces what are MFCs, algal bioreactor and modeling simulations. Chapter 2 demonstrates the method about how to improve the MFC material to enhance the treatment performance for better MFC performance. Chapter 3 describes how to use BES to convert the organics to the renewable gas (e.g., H₂ and CH₄) to recover the energy. Chapters 4 and 5 demonstrate the application of stable isotope probing to study the microbial behavior in the MFC. Chapters 6 to 8 describe the applications of model simulations to optimize MFC and IPB performance. Chapter 9 describes the new reactor to improve the algal harvesting process to obtain more energy from the IPB system. Chapter 10 describes how to use the scale-up IPB system to treat the real wastewater treatment. Chapter 11 finally puts forward some perspectives of IPBs in the wastewater treatment and energy recovery. This dissertation comprehensively gives a big picture about the development of IPB systems in the energy recovery and sustainable wastewater treatment in the future.

Yes / Reverse Osmosis (RO) process can be considered as one of the intensively used pioneering equipment for reusing wastewater of several applications. The recent study presented the development of an accurate model for predicting the dimethylphenol removal from wastewater via RO process. The Response Surface Methodology (RSM) was applied to carry out this challenge based on actual experimental data collected from the literature. The independent variables considered are the inlet pressure (5.83-13.58) atm, inlet temperature (29.5-32) ° C, inlet feed flow rate (2.166-2.583) × 10-4 m3/s, and inlet concentration (0.854-8.049) × 10-3 kmol/m3 and the dimethylphenol removal is considered as the response variable. The analysis of variance showed that the inlet temperature and feed flow rate have a negative influence on dimethylphenol removal from wastewater while the inlet pressure and concentration show a positive influence. In this regard, F-value of 240.38 indicates a considerable contribution of the predicted variables of pressure and concentration against the process dimethylphenol rejection. Also, the predicted R2 value of 0.9772 shows the high accuracy of the model. An overall assessment of simulating the performance of RO process against the operating parameters has been systematically demonstrated using the proposed RSM model.

Conventional desalination plant, municipal water supply and wastewater treatment system are among the most electricity-intensive facilities. Microbial Desalination Cell (MDC) has emerged as a promising technique to capture the chemical energy stored in wastewater directly for desalination, which has the potential to solve the high energy consumption issue in desalination industry as well as wastewater treatment system. The MDC is composed of two critical components, the electrodes (anode and cathode), and the ion-exchange membranes separating the two electrodes which drive anions migrate towards the anode, and cations migrate towards the cathode. The multiple components allow us to manipulate the configuration to achieve most efficient desalination performance. By coupling with Donnan Dialysis or Microbial Fuel Cell, the device can effectively achieve boron removal which has been a critical issue in desalination plants. The uncertainty of water quality of the final desalinated water caused by contaminant back diffusion from the wastewater side can be theoretically explained by two mechanisms, Donnan exchange and molecule transport which are controlled by bioelectricity and concentration gradient. Scaling and fouling is also a factor needs to be taken into consideration when operating the MDC system in real world. With mathematical modeling, we can provide insight to bridge the gap between lab-scale experiments and industrial applications. This study is expected to provide guidance to enhance the efficiency as well as the reliability and controllability of MDC for desalination. / Ph. D. / Water and energy are the world’s most valuable resources. The recent emerging technology, Microbial Desalination Cell (MDC), however, can achieve wastewater treatment, desalination for fresh water production, and energy generation simultaneously. Owing to the anodophilic microorganisms working as organic matter consumer and electron generator, the wastewater can be cleaned and the device can generate electricity through electron flow to drive ion separation for salt removal in the solution. The MDC can be constructed in versatile configurations. Decoupled configuration of anode and cathode allows flexibility of operation and maintenance. Although the MDC has wastewater adjacent to seawater which are separated by a piece of anion exchange membrane, the microorganisms and viruses are effectively blocked by the membrane which has tiny pore size around 1 nm. Back diffusion of contaminants in wastewater into the desalinated water is minimal under bioelectricity generation condition. The MDC has proved to successfully remove various inorganic ions by itself as well as remove non-dissociable boron when coupled to other devices, such as Donnan Dialysis or Microbial Fuel Cell. The water product quality can meet irrigation guideline. Through mathematical modeling tools, we can better understand the MDC process, analyze it, and make informative predictions.

<p dir="ltr">This study investigates the optimization of nitrogen removal in wastewater treatment through a comparative analysis of conventional nitrification-denitrification (N/D) and partial nitritation-anammox (PN/A) processes integrated with anaerobic digestion (AD). Using Bio-Win 6.0 simulations, the research examined system performance across various operational conditions, including temperature ranges (15-35°C), dissolved oxygen levels (0.1-2.0 mg/L), and total Kjeldahl nitrogen concentrations (40-1000 mg/L). Results demonstrated that the PN/A-AD system achieved superior nitrogen removal efficiency (up to 97.5% at 100 mg/L TKN) compared to conventional N/D processes, particularly in treating high-strength nitrogen wastewater. The PN/A system maintained 54.3% removal efficiency even at 1000 mg/L TKN, while requiring less energy (4,614 kW versus 4,682 kW) and producing significantly less sludge (0.57 kg/kg versus 8.07 kg/kg nitrogen removed). Temperature significantly influenced system performance, with optimal conditions observed at 35°C and DO levels between 1-1.5 mg/L. Sensitivity analysis revealed system stability across multiple operational parameters, suggesting robust performance in realworld applications. This research provides valuable insights for designing and optimizing nitrogen removal processes in wastewater treatment plants, particularly for facilities targeting energy efficiency and reduced operational cost.</p>

<p>In the process of making carton boards into Skoghall Mill, are great quantities of water being contaminated. This water has to be treated before it is possible to release into the recipient, Kattfjorden. One of the contaminations that is important to extract from the wastewater, is organic carbon (measured as TOC-total organic carbon) because microbiological breakdown can lead to the bottom becomig free of oxygen.</p><p>The wastewater treatment at Skoghall Mill is done through an external wastewater treatment that is located at the factory. The biological treatment (aerated lagoon) is a 140 000 m3 water pool with surface aerator, which is give oxygen to the water. In the lagoon live microorganisms who performs the biggest part of the TOC-reduction.</p><p>One problem with the lagoon is that the treatment of TOC is considerably worse during wintertime than during summertime. The reduction is during wintertime only 40 %, while during summertime it is about 70-80 %. This seasonal variation can to a large extent be explained by, that the water temperature in the lagoon decreases wintertime. The low water temperature does that the biological activity in the lagoon is reduced, which reduces the TOC-reduction. A second reason can also be that the microorganisms do not have enough bioavailable nutrients that is needed for growth of a new biomass.</p><p>In this thesis the need of nutrient has been examined. In two test pools, addings of nutrient were being done, to come to the conclusion of a good dosage of nutrient which would lead to a larger reduction of TOC, without enlarged quantities of nitrogen/phosphorus in the outgoing water. One of the test pools hold a summer temperature (30°C), and the other test pool hold a winter temperature (10°C). The test was performed this way to see if there would be any difference in the need of nutrient between summertime and wintertime.</p><p>The most important conclusion was that a nutrient dosage to the Skoghall aerated lagoon, rise the TOC-reduction wintertime. It was also concluded that it was foremost the nitrogen that contributed to the raised TOC-reduction, and nitrogen is thereby considered to be the growth restraining element wintertime. It seemed like phosphorus had been overdosed during the tests, while enlarged halts of the substance could be seen in the outgoing water, and an optimal dosage of phosphorus could not be done. The recommendation that came as a results from the tests, was that during wintertime add nitrogen and phosphorus according to TOC:N:P-quota 100:0,75:0,10. To the summer pool was no considerable improvement of the TOC-reduction seen, as a result of the nutrient addings. It is also no reason to dosage nutrients in summertime.</p> / <p>Vid tillverkning av kartong och pappersmassa på Skoghalls Bruk förorenas stora mängder vatten, som därmed måste renas före utsläpp till recipienten, Kattfjorden, en vik i Vänern. En av de föroreningar som är viktig att avlägsna ur avloppsvattnet är organiska kolföreningar (TOC-total organic carbon) eftersom det vid mikrobiologisk nedbrytning av TOC åtgår syre vilket kan leda till att sjöbotten blir syrefri.</p><p>Rening av avloppsvatten på Skoghall Bruk sker genom en extern reningsanläggning som är placerad på bruket. Det biologiska reningssteget i reningsanläggningen är en s.k. luftad damm. Detta är en 140 000 m3 stor vattenbassäng med ytluftare som syresätter vattnet. I dammen lever mikroorganismer vilka utför den största delen av TOC-reduktionen i brukets reningsanläggning.</p><p>Ett problem med dammen är att reningen av TOC är betydligt sämre vintertid än sommartid. Reduktionen av det till dammen inkommande TOC, är vintertid endast ca 40 % medan den sommartid ligger kring 70-80 %. Denna årstidsvariation kan till stor del förklaras av att vattentemperaturen i dammen sjunker vintertid. Den låga temperaturen medför att den biologiska aktiviteten i dammen sjunker, vilket hämmar TOC-reduktionen. En annan orsak till en låg TOC-reduktion kan vara att det för mikroorganismerna råder brist på biotillgängliga närsalter (kväve och fosfor) som behövs för tillväxt av ny biomassa.</p><p>I detta examensarbete har det undersökts behovet av närsalter för att höja TOC-reduktionen. I två laborationsdammar (ca 20 l) skedde doseringar av närsalter i syfte att finna en bra doseringskvot som innebar en ökad reduktion av TOC, utan att det blev förhöjda kväve-/fosforhalter i utgående vatten. En av laborationsdammarna höll sommartemperatur (ca 30°C) och en höll vintertemperatur (ca 10°C) vilket gjordes för att undersöka om det var skillnad av närsaltsbehovet mellan sommar och vintertid.</p><p>Den viktigaste slutsatsen av försöken var att en närsaltsdosering till Skoghalls luftade damm höjer TOC-reduktion vintertid. Det konstaterades att det var kvävet som främst bidrog till den ökade TOC-reduktionen och kväve anses därmed vara det tillväxtbegränsande ämnet vintertid. Fosfor tycktes ha överdoserats under försöken, då det sågs förhöjda halter i utgående vatten, och en optimal dosering av fosfor kunde inte avgöras. Den rekommendation som föll ut av de laborativa försöken var att vintertid dosera kväve och fosfor enligt TOC:N:P-kvot 100:0,75:0,10. Till sommardammen sågs inte någon förbättring av TOC-reduktionen till följd av närsaltstillsatserna, vilket innebär att närsaltsdoseringar sommartid är obefogat. Vidare sågs tendenser till att slammets sedimentationsegenskaper, hos framförallt vinterdammen, blev bättre till följd av närsaltsdosering, men brist på mätdata medför att det är svårt att dra slutsatser om det verkligen varit så.</p>