Thesis (M.Tech.)-Department of Biotechnology, Durban University of Technology, 2006 xvi, 126 leaves / The microbial community present in a laboratory-scale modified Ludzack-Ettinger activated sludge system was investigated using a combination of novel molecular techniques. The parent system was investigated for a duration of one year and samples were taken at regular intervals to determine the profile and structure of the microbial community present within the anoxic and aerobic zones of the MLE system. The combination of molecular techniques included fluorescent in situ hybridisation (FISH) and denaturing gradient gel electrophoresis (DGGE). FISH was performed using oligonucleotide probes, which were complementary to conserved regions of the rRNA for the alpha, beta and gamma subclasses of the gram negative family Proteobacteria as well as a group-specific HGC oligonucleotide probe as a representative of the gram positive actinomycetes branch. The total eubacteria present was determined using the EUB oligonucleotide probes, EUB388, EUB388-II and EUB388-III. The DGGE analysis of PCR-amplified 16S rDNA gene segments was used to examine the microbial community profile in the anoxic and aerobic zones. The profile for each of the zones revealed a number of consistent bands throughout the duration of the laboratory-scale process. However, the profiles obtained suggested that a diverse microbial community existed within the aerobic and anoxic zones. The bands also indicated the presence of dominant and less dominant species of bacteria. Hybridisations obtained from the FISH analyses indicated that the alpha and gamma subclasses were predominant within the anoxic zone and the aerobic zone showed a dominance of the beta subclass of Proteobacteria. The steady state behaviour of the MLE system was confirmed with the results obtained from COD, TKN, nitrates and OUR analytical tests. COD and nitrogen mass balances were conducted to confirm the acceptance of the results obtained for each batch as an indication of the system performance for the MLE model. Nitrogen mass balances indicated an upset in the nitrogen levels for batches two and seven.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban Institute of Technology, 2005 xiv, 114 leaves : ill. 30 cm / The activated sludge process is the mostl used biological treatment process. Engineers and microbiologists are constantly seeking ways to improve process efficiency, which can be attributed to the increasing demand for fresh water supplies and proper environmental management. Since the inception of the activated sludge process, bulking and foaming have been major problems affecting its efficiency. Filamentous bacteria have been identified as the primary cause of bulking and foaming. Numerous attempts have been made to resolve this problem. Some of these attempts were effective as interim measures but failed as long term control strategies. The identification of filamentous bacteria and the study of their physiology have been hampered by the unreliability of conventional microbiological techniques. This is largely due to their morphological variations and inconsistent characteristics within different environments. To fully understand their role in promoting bulking and foaming, filamentous bacteria need to be characterized on a molecular level. The aim of this study was, therefore, to identify filamentous bacteria in pure culture with the purpose of validating these findings to the physiological traits of the pure cultures when they were isolated. Fourteen different filamentous cultures were used for this study. The cultures were identified using specific oligonucleotide probes via fluorescent in situ hybridisation and nucleotide sequencing. Prior to sequencing, an agarose gel and a denaturing gradient gel Electrophoresis profile were determined for each isolate. The various techniques were optimised specifically for the filamentous isolates. The isolates were identified as Gordonia amarae, Haliscomenobacter hydrossis, Acinetobacter sp./Type 1863, Type 021N, Thiothrix nivea, Sphaerotilus natans and Nocardioform organisms.

Thesis (D.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2008. xxiv, 322 leaves / Activated sludge models now in use worldwide for the design and operation of treatment systems use hypothetical concentrations of active organisms. In order to validate and calibrate model outputs, concentrations and activities of organisms responsible for nitrification and denitrification need to be reflected by actual measurements. This research has been initiated by the observation of an increasing gap of suitable techniques that exist in the direct measurement and separation of active biomass components, responsible for COD removal and denitrification.

The conventional wastewater treatment of today was developed aiming to mitigate problems occurring in wastewater recipients such as oxygen depletion and eutrophication. The focus of wastewater management has however broadened and major concern is now focused on the sustainability of the wastewater treatment process itself. Algae based wastewater treatment is an alternative to conventional treatment. It has the potential to yield an acceptable effluent quality at a lower ecological cost. This Degree Project was conducted as part of MOBIT, a project at Mälardalen University. The MOBIT project was aimed at the development of an algae based wastewater treatment process in an activated sludge environment. The aim of this Degree Project was to propose a model describing the dynamics of such a system. The model was constructed in Simulink, based on the River Water Quality Model no. 1. The River Water Quality Model no. 1 was chosen as the basis for modelling because it included the state variables and processes necessary to describe the dynamics of bacteria, algae and pH. The River Water Quality Model no. 1 was, as the name suggests, developed to describe a river system. It was hence considered important to evaluate if the model was applicable to an activated sludge environment. A major obstacle was the fact that no algae based activated sludge system had been studied prior the start of the MOBIT project, the project was pioneering. The lack of system understanding and of measurement data aggravated the evaluation. However, the proposed model was compared to the Activated Sludge Model No. 1 which was known to describe an activated sludge system accurately. The model structure of the River Water Quality Model no. 1 was considered a good starting point for future modelling of the algae based activated sludge process. However, the model set-up proposed in this report does not describe the system sufficiently well. Better system understanding and measurement data is needed in order to develop and calibrate the model. / Dagens konventionella avloppsvattenrening har utvecklats för att minimera utsläpp av näringsämnen och kolföreningar då sådana utsläpp medför övergödning och syrebrist i mottagande vatten. På senare tid har reningsprocessen i sig hamnat i fokus då den är såväl energi- som resurskrävande. Algbaserad avloppsvattenrening är ett alternativ som har potential att ge tillfredsställande rening med ett betydligt mindre ekologiskt fotavtryck. Det här examensarbetet var en del av MOBIT, ett projekt vid Mälardalens högskola. MOBIT syftade till att utvärdera algbaserad avloppsvattenrening i form av en aktivslamprocess. Syftet med examensarbetet var att ta fram en modell för det planerade systemet. Modellen byggdes i Simulink och den baserades på en befintlig modell, River Water Quality Model no. 1. Den befintliga modellen valdes för att den inkluderade alla önskvärda tillståndsvariabler och processer, bland annat de som krävs för att beskriva alg-, bakterie- och pH-dynamik. Som namnet antyder utvecklades River Water Quality Model no. 1 för att beskriva ett flodsystem. Det var därför angeläget att utvärdera huruvida modellen var tillämpbar i en aktivslammiljö. Utvärderingen försvårades av att det vid tiden för examensarbetets utförande ännu inte fanns någon existerande algbaserad aktivslamprocess. Kunskapen om systemet var därför begränsad och det fanns ingen mätdata att kalibrera eller evaluera mot. I brist på mätdata jämfördes den framtagna modellen med en annan modell som var utvecklad för att beskriva just avloppsvattenrening, Activated Sludge Model No. 1. Arbetet resulterade i slutsatsen att River Water Quality Model no. 1 utgör en bra grund för modellering av den algbaserade aktivslamprocessen. Men, den modellkonfiguration som tas fram i denna rapport beskriver inte systemet särskilt bra. Bättre systemförståelse samt tillförlitlig mätdata krävs för att omarbeta och kalibrera den föreslagna modellen. / MOBIT

No description available.

This research followed acetate carbon (C) uptake, metabolism, and fate through a typical modern Kraft pulp and paper mill AS system. Freshly collected mill biomass (AS floc suspensions) was placed under conditions representing four key phases of AS biotreatment: (1) initial acetate uptake by aerated starved AS; (2) ongoing acetate uptake; (3) aerobic metabolism of acetate-loaded AS in acetate-stripped effluent; and (4) anaerobic, settled biomass metabolism. Conditions mimicked the mill system as closely as possible. Acetate carbon uptake kinetics and conversion to CO2, growth products, PHB, and secreted metabolites in each of the four phases were measured. The role of PHB synthesis in the initial stripping of acetate from mill effluent and the PHB production potential of this mill AS were also investigated. / Results showed that acetate was rapidly taken up by high-affinity systems in the AS. During the initial exposure of mill-starved AS, acetate greatly stimulated AS-O2 uptake, and was quickly converted to PHB and CO 2. Upon depletion of available effluent acetate, as occurs in the downstream sections of the aeration tank, O2-uptake rates decreased and the acetate-C stored in AS-PHB was slowly released as CO2, and partly used for growth. Under secondary clarifier-like anaerobic conditions, the AS released virtually no CO2. However, substantial amounts of PHB were used for growth under anaerobic conditions and a small proportion of the original acetate C exited the cells as organic acids.

Current activated sludge models are deterministic in character and are constructed by basing on the fundamental biokinetics. However, calibrating these models are extremely time consuming and laborious. An easy-to-calibrate and user friendly computer model, one of the artificial intelligence techniques, Artificial Neural Networks (ANNs) were used in this study. These models can be used not only directly as a substitute for deterministic models but also can be plugged into the system as error predictors. Three systems were modeled by using ANN models. Initially, a hypothetical wastewater treatment plant constructed in Simulation of Single-Sludge Processes for Carbon Oxidation, Nitrification &amp / Denitrification (SSSP) program, which is an implementation of Activated Sludge Model No 1 (ASM1), was used as the source of input and output data. The other systems were actual treatment plants, Ankara Central Wastewater Treatment Plant, ACWTP and iskenderun Wastewater Treatment Plant (IskWTP). A sensitivity analysis was applied for the hypothetical plant for both of the model simulation results obtained by the SSSP program and the developed ANN model. Sensitivity tests carried out by comparing the responses of the two models indicated parallel sensitivities. In hypothetical WWTP modeling, the highest correlation coefficient obtained with ANN model versus SSSP was about 0.980. By using actual data from IskWTP the best fit obtained by the ANN model yielded R value of 0.795 can be considered very high with such a noisy data. Similarly, ACWTP the R value obtained was 0.688, where accuracy of fit is debatable.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009. / This project was started as a result of strict environmental and health regulations together with a demand for cost effective operation of wastewater treatment plants (WNTPs). The main aim of this project is how to keep effluent concentration below a prescribed limit at the lowest possible cost Due to large fluctuations in the quality and quantity of the influent concentrations, traditional control methods are not adequate to achieve this aim The major drawback with these methods is that the disturbances affect the process before the controller has time to correct the error (Olsson and Newell, 1999: 454). This problem IS addressed through the use of modern control systems Modern control systems are model based predictive algorithms arranged as feed-forward controllers (Olsson and Newell, 1999: 454) Normally a controller is equipped with a constant set point; the goal In this project IS to calculate an optimal DO trajectory that may be sampled to provide a varying optimal set-point for the Activated Sludge Process. In this project an optimal control problem is formulated usmq 00 concentration as a control variable This requires a model of the process to be controlled, a mathematical expressions of the limitations on the process input and output variables and finally the objective functional which consists of the objectives of the control. The structures of the Benchmark plant (developed within the COST 682 working group) and the Athlone WWTPs are used to implement this optimal control strategy in MATLAB, The plant's full models are developed based on the mass balance principle incorporating the activated sludge biological models. ASM1, ASM2 ASM2d and ASM3 (developed by the IWA. working groups) To be able to develop a method that may later on be used ~or online control. the full models are reduced based on the technique in Lukasse (1996) To ensure that the reduced models keep the same prediction capabilities as the full models paran-eters of the reduced models are calculated based on the Least Squares principle. The formulated optimal control problem IS solved based on the decomposition-coordination method that involves time decomposition 111 a two layer structure, MATLAB software is developed to solve the problems for parameter estimation full and reduced model simulation and optimal control calculation for the considered different cases of plant structures and biological models, The obtained optimal DO trajectories produced the effluent state trajectories within prescribed requirements. These DO trajectories may be implemented in different SCADA systems to be tracked as set points or desired trajectories by different types of controllers.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016. / Polymers used as flocculants in the secondary sludge dewatering process are one of the most expensive inputs in these plants. The disadvantage is that these polymers cannot be recycled. Currently, controlling of polymer dosing rate is done by trial and error method. It has been shown that huge savings can be made by optimising the polymer dosing using rheological properties. It is not an easy task to optimise this process because of changing sludge characteristics on a daily, seasonal and annual basis. To try and optimise polymer dosing and polymer concentration, the variation in rheological properties needs to be understood first. The correlation between the process parameters and the rheological properties needs to be determined. There is currently no database of rheological properties of secondary wastewater sludge feeding belt filter presses available. To address these issues, a 12 week assessment of the rheological properties of the sludge feed to the belt filter press before and after conditioning in four wastewater treatment plants in Cape Town was conducted. The rheological properties were determined using an MCR-51 rheometer with parallel plate geometry under controlled temperature. After concluding the assessment, a 3-level Box-Behnken factorial trial was conducted at Plant K wastewater treatment plant to statistically analyse the correlation and/or interactions between the process parameters (sludge feed flow rate, polymer dosing concentration, polymer dosing rate and belt press speed) and the rheological properties of the sludge to optimise the plant performance.

Thesis submitted in compliance with the requirements for the Doctoral Degree in Technology: Biotechnology at the Durban Institute of Technology, 2003. / Globally, wastewaters emanating from edible oil manufacturers contain high organic (BOD & COD) and phosphate loads and known for creating shock-loading problems for the receiving wastewater treatment installations. Discharge of poor quality final effluents also negatively impact on and cause eutrophication of natural water sources such as rivers and dams. In South Africa, a large concentration ofthe edible industries are localized in the Pietermaritzburg region of Kwa-Zulu Natal and have been regularly associated with discharge of poor quality final effluent that did not subscribe to municipal regulation standards. Current treatment of choice for wastewater's in the edible oil industry have been limited primarily to dissolved air flotation combined with the use of chemical coagulants or physical separation of oil and grease via a gravity fat trap and subsequent pH correction. These physico-chemical methods have achieved limited success and the emulsified grease tends to clog sewer pipes and pumps producing poor quality effluents. Therefore, the aim of the current research was to develop suitable treatment technology focussing on adapting activated sludge process to remediate edible oil effluents and determine the microbial community of the process using novel molecular techniques. / D