Membrane aerators and stirring systems for the operation in large and small wastewater treatment plants

1996 ◽  
Vol 34 (3-4) ◽  
pp. 329-338 ◽  
Author(s):  
Marcus W. A. Höfken ◽  
Peter Huber ◽  
Marcus Schäfer ◽  
Ralf Steiner
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Energy Demand ◽  
Wastewater Treatment Plants ◽  
Air Bubbles ◽  
Process Step ◽  
Optimum System ◽  
Activated Sludge Processes ◽  
Silicone Membranes

Stirring and aeration processes are the major operations needed for effective wastewater treatment. Especially in activated sludge processes and the variants of this process stirring and aeration systems need to be chosen carefully since both operations are crucial for the purification power and the energy demand of wwtp's. The aim of the present work is to define the demands on stirring and aeration systems for activated sludge treatment plants, to give an overview about suitable systems currently available on the market including latest developments and to give advice how to choose the optimum system. A brief review of the literature and the market of stirring and aeration systems leads to a simple classification of the existing numerous systems. In order to choose the optimum system, first one has to decide, about the demands in each process step. In anaerobic and anoxic reactors the use of hyperboloid stirring systems or combined hyperboloid stirring and aeration systems which distribute small air bubbles throughout the entire reactor in the aeration mode (for intermittent aeration) and gently circulate bacteria flocks in the stirring mode is recommended. For aerobic processes like BOD-removal and nitrification highly efficient membrane aerating systems using silicone membranes are recommended.

scholarly journals Deep learning-based morphology classification of activated sludge flocs in wastewater treatment plants

2021 ◽  
Author(s):  
Hisashi Satoh ◽  
Yukari Kashimoto ◽  
Naoki Takahashi ◽  
Takashi Tsujimura
Keyword(s):  
Wastewater Treatment ◽  
Deep Learning ◽  
Activated Sludge ◽  
Morphological Change ◽  
Wastewater Treatment Plants ◽  
Filamentous Bacteria ◽  
Sludge Flocs

A deep learning-based two-label classifier 1 recognized a 20% morphological change in the activated flocs. Classifier-2 quantitatively recognized an abundance of filamentous bacteria in activated flocs.

Modelling and simulation of the steady-state of secondary settlers in wastewater treatment plants

2001 ◽  
Vol 43 (7) ◽  
pp. 39-46 ◽  
Author(s):  
I. Queinnec ◽  
D. Dochain
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wastewater Treatment ◽  
Steady State ◽  
Activated Sludge ◽  
Parameter Identification ◽  
Wastewater Treatment Plants ◽  
Operating Conditions ◽  
Sensitivity Studies ◽  
Activated Sludge Processes

This paper discusses the steady-state modelling of thickening in circular secondary settlers of activated sludge processes. The limitations of the solid flux theory basic models to represent steady-state operating conditions serve as a basis to introduce more sophisticated models derived from computational fluid dynamics. Parameter identification and sensitivity studies have been performed from lab-scale continuous experiments.

The limits and ultimate possibilities of technology of the activated sludge process

2008 ◽  
Vol 58 (8) ◽  
pp. 1671-1677 ◽  
Author(s):  
A. F. van Nieuwenhuijzen ◽  
A. G. N. van Bentem ◽  
A. Buunnen ◽  
B. A. Reitsma ◽  
C. A. Uijterlinde
Keyword(s):  
Wastewater Treatment ◽  
The Netherlands ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Method ◽  
Activated Sludge Process ◽  
Municipal Wastewater Treatment ◽  
Nitrogen And Phosphorus ◽  
Activated Sludge Processes

The (low loaded) biological nutrient removing activated sludge process is the generally accepted and applied municipal wastewater treatment method in the Netherlands. The hydraulical and biological flexibility, robustness and cost efficiency of the process for advanced removal of nutrients like nitrogen and phosphorus without (too much) chemicals results in a wide application of the activated sludge process within Dutch waterboards. Presumably, wastewater treatment plants will have to contribute to the improvement of the quality of the receiving surface waters by producing cleaner effluent. In this perspective, the Dutch research organisation STOWA initiated a research project entitled “The Boundaries of the Activated Sludge Process” to investigate the possibilities and limitations of activated sludge processes to improve the effluent quality. It is concluded that the activated sludge process as applied and operated at WWTP's in the Netherlands has the potential to perform even better than the current effluent discharge standards (10 mg Ntotal/l and 1 mg Ptotal/l). Reaching the B-quality effluent (<5mg Ntotal/l and <0.3 mg Ptotal/l) will be possible at almost all WWTPs without major adjustments under the conditions that:   the sludge load is below 0.06 kg BOD/kg TSS.d   the internal recirculation is above 20   the BOD/N ratio of the influent is above 3. Complying with the A-quality effluent (<2.2 Ntotal/l and <0.15 mg Ptotal/l) seems to be difficult (but not impossible) and requires more attention and insight into the activated sludge process. Optimisation measures to reach the A-quality effluent are more thorough and are mostly only achievable by additional construction works (addition of activated sludge volume, increasing recirculation capacity, etc.). It is furthermore concluded that the static HSA-results are comparable to the dynamic ASM-results. So, for fast determinations of the limits of technology of different activated sludge processes static modelling seems to by sufficient.

scholarly journals The potential of denitrification for the stabilization of activated sludge processes affected by low alkalinity problems

2007 ◽  
Vol 50 (2) ◽  
pp. 329-337 ◽  
Author(s):  
Heike Hoffmann ◽  
Tatiana Barbosa da Costa ◽  
Delmira Beatriz Wolff ◽  
Christoph Platzer ◽  
Rejane Helena Ribeiro da Costa
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Ammonia Concentration ◽  
Denitrification Rate ◽  
Activated Sludge Reactor ◽  
Denitrification Activity ◽  
Activated Sludge Processes

In this study, the problems provoked by nitrification of wastewater with low alkalinity were analyzed in a pilot sequencing batch activated sludge reactor (SBR). Decrease in pH resulted in disappearence of protozoa. De-flocculation of the activated sludge floc started below pH 6.5, resulting in enhanced effluent turbidity and loss of bacteria. Nitrification efficiency was affected below pH 6.2. The denitrification activity was not sufficient to keep up the pH, due to a low C/N ratio of the wastewater. Based on alkalinity and ammonia concentration of the wastewater and the necessary denitrification rate to prevent operational problems, was developed a prognostic diagram. The applicability of this diagram was tested for the SBR with excellent results. The diagram could be applied to optimize the operation of wastewater treatment plants affected by problems with low alkalinity wastewater.

scholarly journals Oxygen requirements in relation to sludge age in wastewater treatment plants

2021 ◽  
Vol 899 (1) ◽  
pp. 012070
Author(s):  
Liana Kemmou ◽  
Georgios Samiotis ◽  
Elisavet Amanatidou
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Utilization Rate ◽  
Oxygen Utilization ◽  
Waste Sludge ◽  
Solids Retention ◽  
Oxygen Requirements ◽  
Oxygen Utilization Rate ◽  
Activated Sludge Processes

Abstract Sustainability of activated sludge (AS) wastewater treatment processes is inexplicably linked to minimization of secondary wastes, such as waste sludge, as well as energy requirements for achieving effluent quality standards. Oxygen requirements and waste sludge management accounts for most of energy consumption in aerobic AS wastewater treatment plants (WWTPs). In this study, a novel, highly aerobic AS process, entitled complete solids retention AS process (CRAS), is being evaluated in terms of waste sludge production and biomass oxygen utilization rate. Aim of this work is to study the effect of solids retention time (SRT) on observed sludge yields and on oxygen requirements for respiration in order to evaluate CRAS process as a sustainable alternative to typical activated sludge processes.

Floc size distribution and bacterial activities in membrane separation activated sludge processes for small-scale wastewater treatment/reclamation

1997 ◽  
Vol 35 (6) ◽  
pp. 37-44 ◽  
Author(s):  
Boran Zhang ◽  
Kazuo Yamamoto ◽  
Shinichiro Ohgaki ◽  
Naoyuki Kamiko
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Membrane Separation ◽  
Small Scale ◽  
Nitrification Rate ◽  
Floc Size ◽  
Denitrification Activity ◽  
Concentration Changes ◽  
Activated Sludge Processes

Activated sludges taken from full-scale membrane separation processes, building wastewater reuse system (400m3/d), and two nightsoil treatment plants (50m3/d) as well as laboratory scale membrane separation bioreactor (0.062m3/d) were analyzed to characterize membrane separation activated sludge processes (MSAS). They were also compared with conventional activated sludges(CAS) taken from municipal wastewater treatment plants. Specific nitrification activity in MSAS processes averaged at 2.28gNH4-N/kgMLSS.h were higher than that in CAS processes averaged at 0.96gNH4-N/kgMLSS.h. The denitrification activity in both processes were in the range of 0.62-3.2gNO3-N/kgMLSS.h without organic addition and in the range of 4.25-6.4gNO3-N/kgMLSS.h with organic addition. The organic removal activity in nightsoil treatment process averaged at 123gCOD/kgMLSS.h which was significantly higher than others. Floc size distributions were measured by particle sedimentation technique and image analysis technique. Flocs in MSAS processes changed their sizes with MLSS concentration changes and were concentrated at small sizes at low MLSS concentration, mostly less than 60 μm. On the contrary, floc sizes in CAS processes have not much changed with MLSS concentration changes and they were distributed in large range. In addition, the effects of floc size on specific nitrification rate, denitrification rate with and without organic carbon addition were investigated. Specific nitrification rate was decreased as floc size increased. However, little effect of floc size on denitrification activity was observed.

scholarly journals The capacity of wastewater treatment plants drives bacterial community structure and its assembly

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Young Kyung Kim ◽  
Keunje Yoo ◽  
Min Sung Kim ◽  
Il Han ◽  
Minjoo Lee ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Community Structure ◽  
Bacterial Community ◽  
Activated Sludge ◽  
Community Assembly ◽  
Bacterial Communities ◽  
Wastewater Treatment Plants ◽  
High Capacity ◽  
Operating Conditions ◽  
Rrna Gene

Abstract Bacterial communities in wastewater treatment plants (WWTPs) affect plant functionality through their role in the removal of pollutants from wastewater. Bacterial communities vary extensively based on plant operating conditions and influent characteristics. The capacity of WWTPs can also affect the bacterial community via variations in the organic or nutrient composition of the influent. Despite the importance considering capacity, the characteristics that control bacterial community assembly are largely unknown. In this study, we discovered that bacterial communities in WWTPs in Korea and Vietnam, which differ remarkably in capacity, exhibit unique structures and interactions that are governed mainly by the capacity of WWTPs. Bacterial communities were analysed using 16S rRNA gene sequencing and exhibited clear differences between the two regions, with these differences being most pronounced in activated sludge. We found that capacity contributed the most to bacterial interactions and community structure, whereas other factors had less impact. Co-occurrence network analysis showed that microorganisms from high-capacity WWTPs are more interrelated than those from low-capacity WWTPs, which corresponds to the tighter clustering of bacterial communities in Korea. These results will contribute to the understanding of bacterial community assembly in activated sludge processing.

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