Benzo-a-pyrene, a carcinogenic polycyclic aromatic hydrocarbon, was injected into the aeration tank of an activated sludge pilot plant in an investigation to determine the ability of activated sludge to effectively treat this compound. The method employed to segregate Benzo-a-pyrene from other organics was a modified Soxhlet technique followed by gas chromatographic analysis. The amount of Benzo-a-pyrene detected in the effluent, supernatant, sludge filtrate and sludge cake was tabulated to determine the mechanism of removal. The experimental results indicated that adsorption appeared to be.the primary mechanism of removal. The concentration of Benzo-a-pyrene in the effluent collected from the pilot plant was below the level of detection by gas chromatography. On the basis of the experimental evidence activated . sludge provides satisfactory treatment for wastes containing low concentrations (i.e. 0.5 mg/l) of Benzo-a-pyrene, a carcinogenic polycyclic aromatic hydrocarbon. / Master of Science

The capability of the activated sludge process to operate with sea water included in the influent substrate. Sea water was added at various percentages from 5-40. The study concluded that from a biological standpoint the activated sludge process could operate successfully. However, rapid settling problems because of a build up of total solids became the limiting factor. / Master of Science

Treatment of municipal and industrial wastewaters results in the production of wastes in the form of sludge. Since the quantity and characteristics of sludge depend upon the degree of treatment, the upgrading of treatment facilities has had the effect of increasing sludge production. Since the quantity of sludge is a function of the type of treatment provided, any attempt to minimize sludge handling should begin at the source. The hydrolytic assist activated sludge process provides positive control of the mixed liquor solids and is effective in the disposal of organic sludge created in the wastewater treatment process. In theory, this modification involves the hydrolysis of waste activated sludge by acid addition to a pH of 1.0 or with base addition to a pH of 13.0. Hydrolysis is followed by autoclaving at 15 psi and 121°c for a period of five hours. This treatment will solubilize most of the cellular material which can then be reintroduced to the aeration tank after pH neutralization. No sludge is wasted; it is all recycled as hydrolyzed sludge. The main objective of this research was to operate laboratory activated sludge units over a range of Qc values to determine effects and differences in process performance and operation for the hydrolytic assist mode. Results obtained during this study indicate that COD removal efficiency for the hydrolytic assist is compatible with the conventional process. In addition, the hydrolytic assist process proved to be an effective disposal method for sludge produced in the activated sludge process. / M.S.

Handling and disposal of residual solids from wastewater treatment plants is an expensive and difficult task. The acid hydrolytic assist activated sludge process is one method of minimizing sludge production from a biological wastewater treatment process. Acid hydrolysis of waste sludge involves pH adjustment to 1.0 or less followed by heat treatment. The hydrolyzed sludge can then be adjusted to a neutral pH and recycled to the treatment process as soluble organic material. In effect, hydrolysis promotes cellular autodigestion by artificially inducing the normally difficult metabolic steps. The use of hydrolysis in the extended aeration process allows periodic sludge wasting for control purposes but avoids the problem of ultimate sludge disposal. Previous research was limited to the use of hydrolysis in the extended aeration process. The effect of mean cell residence time, Θ_c, on an activated sludge process utilizing hydrolysis had not been evaluated. Also, only limited information is currently available regarding the kinetics of wastewater treatment with the hydrolytic assist activated sludge process. The purpose of this research was to gain additional insight into the hydrolytic assist activated sludge process with regard to mean cell residence time and the kinetics of wastewater treatment. Determination of the relative effect of hydrolysis on nitrification in the activated sludge process was a secondary objective of this study. Mathematical and stoichiometric equations were used to predict process performance characteristics. A laboratory investigation was then conducted to obtain actual operational results for comparison. A description of the investigative procedures and results is included along with a review of the literature. / Master of Science

published_or_final_version / Civil Engineering / Master / Master of Philosophy

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.

Thesis (MEng (Civil Engineering))--University of Stellenbosch, 1983. / 129 leaves printed on single pages, preliminary pages and numbered pages 1-1 – 12.5. Includes bibliography, list of abbreviations and list of figures. / Digitized at 300 dpi black and white PDF format (OCR), using KODAK i 1220 PLUS scanner. / ENGLISH ABSTRACT: The remedy of a bulking sludge was investigated by the principle of selection of microorganisms. Selection of microorganisms in activated sludge was achieved by putting a selection compartment, with a high substrate concentration, ahead of the main aeration basin. The initial results in the experiments indicated selection of microorganisms and a reduction of SVI, but complete selection of microorganisms could not be obtained. / AFRIKAANSE OPSOMMING: Die herstel van 'n uitdyende slyk is deur die beginsel van selektering van mikroorganismes ondersoek. Selektering van mikroorganismes in geaktiveerde slyk is toegepas deur n seleksie kompartement met 'n hoë substraatkonsentrasie, voor die groot belugtingsbak te plaas. Die aanvanklike resultate wat verkry is, het selektering van mikroorganismes en 'n verlaging in die SVI getoon, maar volledige selektering van mikroorganismes kon nie verkry word nie.

<p>För att simulera aktivslamprocessen på ett reningsverk krävs en dynamisk modell som realistiskt beskriver processen. 1987 kom IWA, International Water Association med ASM1, Activated Sludge model no. 1 som fortfarande är den mest använda modellen för att beskriva denna process. I detta examensarbete har ASM1 används för att beskriva aktivslamprocessen på Henriksdals reningsverk i Stockholm. Arbetet har utförts som en del i ett europeiskt projekt, HIPCON (Holistic Integrated Process CONtrol) på IVL, Svenska Miljöinstitutet AB.</p><p>Arbetet har gått ut på att ta fram en modell som realistiskt beskriver aktivslamprocessen och eftersedimenteringen. För att göra detta har en referensmodell i MATLAB/Simulink använts som grund och byggts om för att likna processen vid Henriksdal. Denna modell i Simulink använder ASM1 för att beskriva aktivslamprocessen. Eftersedimenteringen modelleras med en massbalansmodell där sedimenteringshastigheten beskrivs av en dubbelexponentiell sedimenteringsfunktion. Både ASM1 och sedimenteringsfunktionen använder en mängd olika parametrar för att beskriva processerna och dessa måste kalibreras fram för den process som skall modelleras. Aktivslamprocessen är en biologisk process som beror på en mängd yttre och inre faktorer och är unik för varje reningsverk. Därför finns det inte något enkelt sätt att kalibrera en modell på och information för det enskilda reningsverket i fråga måste tas fram. I detta arbete har två mätkampanjer utförts på Henriksdal för att få mätserier till kalibrering och validering samt information om avloppsvattnets sammansättning. Litteraturstudier har också genomförts för att få information om vilka parametervärden som är av störst intresse för modellen samt i vilket område varje parameter kan förväntas finnas.</p><p>Arbetet har sedan gått ut på att efter riktlinjer för kalibrering funna i litteraturen ta fram en modell som så realistiskt som möjligt beskriver processen på Henriksdal. Först genomfördes en kalibrering med medelvärden för att hitta jämviktstillstånd och därmed en stabil modell på länge sikt. Utifrån den modellen utfördes sedan en dynamisk kalibrering för att få en modell som beskriver även kortsiktiga och snabba förändringar. Till sist utfördes en validering för att kontrollera om modellen fungerar även för en dataserie som ej använts vid kalibrering. Den framtagna modellen fungerade mycket bra för att modellera medelvärden på lång sikt. För snabba förändringar verkade modellen ligga fel i tiden och troligtvis var den reella uppehållstiden kortare än den teoretiska och bidrar till sämre modellanpassning.</p> / <p>To simulate the activated sludge process at a wastewater treatment plant a dynamic model that describes the process is needed. In 1987 IWA, International Water Association presented ASM1, Activated Sludge Model No.1 which still is the most widely used model for this process. In this thesis the ASM1 has been used to describe the activated sludge process. The work is a part of a European project, HIPCON (Holistic Integrated Process CONtrol) at IVL, Swedish Environmental Research Institute.</p><p>The main objective of the work was to calibrate a model that realistically describes the activated sludge process and secondary sedimentation at Henriksdal wastewater treatment plant in Stockholm. A benchmark model in MATLAB/Simulink was used as a base and rebuilt and extended to fit the process of Henriksdal. In the model ASM1 is used to describe the activated sludge process. The settler is modelled with a mass balance model where the settling velocity is described by a double exponential function. The parameters used in both models have to be calibrated to fit the wastewater treatment plant. To find information about Henriksdal two measuring campaigns were performed to provide data for calibration and validation and to gather information about the composition of the incoming wastewater. From this data a model was developed and calibrated for the process at Henriksdal. After calibration the obtained model worked very well for modelling average values but did not adjust quite as well to fast dynamic changes.</p>