scholarly journals Modeling and optimizations of mixing and aeration processes in bioreactors with activated sludge

2021 ◽  
Vol 2130 (1) ◽  
pp. 012027
Author(s):  
J Zaburko ◽  
G Łagód ◽  
M K Widomski ◽  
J Szulżyk-Cieplak ◽  
B Szeląg ◽  
...  

Abstract Mixing aimed at homogenization of the volume of bioreactors with the activated sludge is of great importance for the proper course of the wastewater treatment process. It affects both the efficiency of pollutants removal and the properties of the activated sludge related to its sedimentation. The mixing process in bioreactors can be carried out in different ways. In batch bioreactors in the aeration phase or flow bioreactors in aerobic chambers, mixing is carried out through aeration systems. These systems should aerate the activated sludge flocs for efficient biological treating of wastewater, as well as effectively homogenize the volume of the bioreactor. Hence, it is important to choose such a design of the aeration system and its operation settings that provide the amount of air ensuring the exact amount of oxygen for the implementation of technological processes, counteract sedimentation of sludge at the bottom of the reactor, are reliable as well as economical in operation (demand of electric energy). The paper presents the model studies aimed at optimization of the design and settings of aeration and mixing systems used in active sludge bioreactors.

1999 ◽  
Vol 40 (4-5) ◽  
pp. 187-194 ◽  
Author(s):  
C. Collivignarelli ◽  
G. Bertanza

This paper deals with the development of technologies aimed to upgrade existing waste water treatment plants, paying attention to high process efficiencies and low costs. We established conditions for good N removal efficiencies in extended aeration activated sludge plants which are not equipped with specific denitrification steps. The experimental process is based on establishing conditions in the biological reactor which allow simultaneous nitrification and denitrification without alternating (in time or in space) anoxic and aerobic phases; the aeration system is controlled by means of dissolved oxygen and/or redox potential measurements. The research was carried out on two real plants (design size: 2,500 p.e. and 440,000 p.e. respectively). The main advantages of this process (even if some aspects are still under investigation) are: total N removal efficiencies similar to a pre-denitrification process, without the need for an anoxic basin and decrease of operating costs (savings in electric energy consumption in particular) due to the low oxygen concentration required in the biological reactor.


2016 ◽  
Vol 75 (3) ◽  
pp. 552-560 ◽  
Author(s):  
Oliver Schraa ◽  
Leiv Rieger ◽  
Jens Alex

During the design of a water resource recovery facility, it is becoming industry practice to use simulation software to assist with process design. Aeration is one of the key components of the activated sludge process, and is one of the most important aspects of modelling wastewater treatment systems. However, aeration systems are typically not modelled in detail in most wastewater treatment process modelling studies. A comprehensive dynamic aeration system model has been developed that captures both air supply and demand. The model includes sub-models for blowers, pipes, fittings, and valves. An extended diffuser model predicts both oxygen transfer efficiency within an aeration basin and pressure drop across the diffusers. The aeration system model allows engineers to analyse aeration systems as a whole to determine biological air requirements, blower performance, air distribution, control valve impacts, controller design and tuning, and energy costs. This enables engineers to trouble-shoot the entire aeration system including process, equipment and controls. It also allows much more realistic design of these highly complex systems.


2018 ◽  
Vol 178 ◽  
pp. 09022
Author(s):  
Nina Zaletova ◽  
Nadezhda Morozova

The purpose of the paper was to study the dehydrogenase activity (DHA) of activated sludge in aeration tank. The article describes a change in enzyme activity, (dehydrogenase activity of sludge-DHA) of activated sludge while various time of aeration as well as various dose in sludge of aeration tank. Assessment changes enzyme activity were done on two indicators - on DHAor. (original dehydrogenase activity of sludge) and DHAH2O (dehydrogenase sludge activity with tap water). In the first case - DHA with the actual substrate, in the second case - DHA with poorly concentrated substrate. The work was performed on a pilot installation consisting of four models of aeration tanks blocked with sedimentation tanks, on a real city waste water. Working doses of sludge in biological wastewater treatment process was ranged from 2 to 6 g/l, time of aeration in aeration tanks changed from 3.5. up to 0.8 hours. Experimental studies have shown that regardless of the size of working sludge dose in aeration tank character of changes DHA or and DHAH2O is identical.


2013 ◽  
Vol 68 (12) ◽  
pp. 2654-2660 ◽  
Author(s):  
Dorota Gendaszewska ◽  
Ewa Liwarska-Bizukojc

Data concerning the biodegradability and ecotoxicity of ionic liquids (ILs) obtained so far are insufficient in the context of IL removal from wastewater in activated sludge systems. Thus, in this work the selected imidazolium ionic liquids and two organic solvents (methanol and acetone) were tested with respect to their influence on activated sludge processes, particularly on the morphology of sludge flocs. The presence of ionic liquids with the chemical structure of 1-alkyl-3-methyl imidazolium bromide in wastewater did not deteriorate biological wastewater treatment processes if their concentration was not higher than 5 mg l−1. Regarding the structure of the ILs studied, the longer the alkyl substituent was, the stronger the effect on sludge flocs. The highest decrease in activated sludge floc area and biomass concentration was exerted by the ionic liquid with the longest alkyl chain, i.e. 1-decyl-3-methylimidazolium bromide. The action of both methanol and acetone on floc size, activated sludge concentration and efficiency of organic pollutants removal was weaker compared to all tested 1-alkyl-3-methyl imidazolium bromides.


1986 ◽  
Vol 21 (1) ◽  
pp. 130-140 ◽  
Author(s):  
Da-hong Li ◽  
J. J. Ganczarczyk

Abstract The computerized image analysis system has been successfully used for determination and statistical processing of the following geometric characteristics of activated sludge flocs: longest dimension, breadth, equivalent diameter, cross-sectional area, perimeter, elongation, and circularity. These parameters could be effectively and precisely determined by the system applied. In addition, the studied method, as compared to direct microscope observation and photography floc-sizing methods, was found to be more accurate, less time-consuming, and less dependent on the investigators.


1991 ◽  
Vol 24 (7) ◽  
pp. 59-64 ◽  
Author(s):  
R. W. Szetela

Steady-state models are presented to describe the wastewater treatment process in two activated sludge systems. One of these makes use of a single complete-mix reactor; the other one involves two complete-mix reactors arranged in series. The in-series system is equivalent to what is known as the “two-phase” activated sludge, a concept which is now being launched throughout Poland in conjunction with the PROMLECZ technology under implementation. Analysis of the mathematical models has revealed the following: (1) treatment efficiency, excess sludge production, energy consumption, and the degree of sludge stabilization are identical in the two systems; (2) there exists a technological equivalence of “two-phase” sludge with “single-phase” sludge; (3) the “two-phase” system has no technological advantage over the “single-phase” system.


Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 984
Author(s):  
Pedro Cisterna-Osorio ◽  
Claudia Calabran-Caceres ◽  
Giannina Tiznado-Bustamante ◽  
Nataly Bastias-Toro

This research studies the incidence of the type of substrate, soluble or particulate, in the emergence, development, and inhibition of bulking in activated sludge systems. It was evaluated using the sludge volume index (SVI), mixing liquor-suspended solids (MLSS), microscopic analysis of biomass, and effluent suspended solids (ESS). In the first experiment, four sequencing batch reactors (SBRs) were fed with soluble substrate at a fixed mass, while the mass of the particulate substrate varied, as those (saccharose mass/flour mass) ratios were 3:1, 3:2, 3:3 and 3:4., with a deficit ranging from 20 to 30% compared to the ratio recommended. The four SBRs have similar MLSS, IVL, and ESS. From day 30, with a deficit from 80 to 90%, the influents have ratios 1/1 and 1/2 until 48 days. The SBRs present IVL between 600 and 730 mL/g and ESS from 370 to 440 mg/L; unlike influents with ratios 1/3 and 1/4, they present IVL between 170 and 185 mL/g, and ESS from 260 to 270 mg/L. The favorable effect of particulate matter is categorical. In the second set of experiments, two SBRs were studied: SBR 1 fed with saccharose, and SBR 2 with flour; there is a lack of nutrients causing bulking in SBRs. Once the nutrient deficiency condition is changed in day 11 to excess, after 22 days, the SVI was 190 mL/g, ESS was 360 mg/L, and MLSS was 2000 mg/L for influents with saccharose; the influent with flour, with an SVI of 80 mL/g, ESS of 100 mg/L, and MLSS of 4000 mg/L, shows faster and more consistent recovery with the particulate substrate. Therefore, the proposal is to add particulate substrate-like flour to active sludge plants facing bulking. It is a clean, innocuous and sustainable alternative to processes that use chemical reagents.


Author(s):  
Hisashi Satoh ◽  
Yukari Kashimoto ◽  
Naoki Takahashi ◽  
Takashi Tsujimura

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.


1999 ◽  
Vol 39 (6) ◽  
pp. 61-68 ◽  
Author(s):  
Klangduen Pochana ◽  
Jürg Keller

Experiments have been performed to gain an understanding of the conditions and processes governing the occurrence of SND in activated sludge systems. Sequencing batch reactors (SBRs) have been operated under controlled conditions using the wastewater from the first anaerobic pond in an abattoir wastewater treatment plant. Under specific circumstances, up to 95% of total nitrogen removal through SND has been found in the system. Carbon source and oxygen concentrations were found to be important process parameters. The addition of acetate as an external carbon source resulted in a significant increase of SND activity in the system. Stepwise change of DO concentration has also been observed in this study. Experiments to determine the effect of the floc size on SND have been performed in order to test the hypothesis that SND is a physical phenomenon, governed by the diffusion of oxygen into the activated sludge flocs. Initial results support this hypothesis but further experimental confirmation is still required.


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