Short term effects of dissolved oxygen concentration on the turbidity of the supernatant of activated sludge

1998 ◽  
Vol 38 (3) ◽  
pp. 25-33 ◽  
Author(s):  
Britt-Marie Wilén ◽  
Peter Balmér
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Adsorption Capacity ◽  
Full Scale ◽  
Aeration Tank ◽  
Batch Reactors ◽  
Short Term ◽  
Colloidal Material ◽  
Do Concentration ◽  
Short Term Effects

Short term effects of dissolved oxygen (DO) concentration on the supernatant turbidity of activated sludge were studied in batch reactors, continuous reactors and in a full scale plant. Adsorption of colloidal material onto activated sludge was studied in batch reactors. The adsorption capacity of colloidal material, expressed as removal of turbidity, was larger in aerobic than in anaerobic conditions. The difference in adsorption capacity between high (≥5 mg/l) and low (<0.5 mg/l) DO concentrations was small. Experiments were made in pilot scale completely mixed reactors where the oxygen supply was turned off during different periods of length (1-4 hours). The turbidity increased directly when the anaerobic period started and decreased when the aerobic period started. Similar results were obtained when the influent was turned off. A few full scale experiments were carried out. The aerators were adjusted to change the DO concentration along the aeration tank (plug flow) for periods of 3-6 hours. Low DO concentrations by the end of the aeration tank produced a turbidity increase of the effluent, while low DO concentrations in the first half of the aeration tank did not affect the turbidity to a large extent.

scholarly journals Microbial community similarity and dissimilarity inside and across full-scale activated sludge processes for simultaneous nitrification and denitrification

2020 ◽  
Vol 81 (2) ◽  
pp. 333-344
Author(s):  
Jianfeng Wen ◽  
Mark W. LeChevallier ◽  
Wendong Tao
Keyword(s):  
Microbial Community ◽  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Relative Abundance ◽  
Nitrogen Removal ◽  
Full Scale ◽  
Batch Reactors ◽  
Simultaneous Nitrification And Denitrification ◽  
Sequencing Batch Reactors ◽  
Mixed Liquor

Abstract Simultaneous nitrification and denitrification under low dissolved oxygen conditions is an energy-saving modification of the activated sludge process to achieve efficient nitrogen removal. Geographically distinct full-scale treatment plants are excellent platforms to address the links of microbial community with operating parameters. Mixed liquor samples were collected from a sequencing batch reactor plant, oxidation ditch plant, and step-feed activated sludge plant. Next-Generation Sequencing of the samples showed that the microbial communities were similar at the phylum level among the plants, being dominated by Proteobacteria. Microbial composition of functional groups was similar between the react fill and react phases of the sequencing batch reactors, among four sequencing batch reactors, and among four oxidation ditches. Nitrospira was the only identified genus of autotropic nitrifying bacteria with a relative abundance of 2.2–2.5% in the oxidation ditches and 0.4–0.7% at the other plants. Heterotrophic nitrifying–aerobic denitrifying bacteria were dominated by Dechloromonas with a relative abundance of 0.4–1.0%. Microbial community composition and nitrogen removal mechanisms were related to overall level and local zonation of dissolved oxygen, mixed liquor suspended solids concentration, nitrogen and organic loadings, and solids retention time. Low dissolved oxygen and low organic and nitrogen loadings favored growth of Nitrospira.

The Effect of Short-Term Dissolved Oxygen Transients on Activated Sludge

2008 ◽  
Vol 43 (2-3) ◽  
pp. 201-210 ◽  
Author(s):  
Yi Zhang ◽  
D. Grant Allen
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Physiological Response ◽  
Extracellular Polymeric Substances ◽  
Suspended Solid ◽  
Soluble Proteins ◽  
Short Term ◽  
Batch System ◽  
Do Concentration ◽  
Low Do

Abstract The effect of short-term dissolved oxygen (DO) disturbances on municipal activated sludge was studied, in a batch system, with respect to changes in supernatant turbidity, suspended solid (SS) concentrations, proteins, polysaccharides, and cations in the extracellular polymeric substances (EPS). Results showed that turbidity increased by 20 times when the DO concentration decreased below 0.5 mg/L, and supernatant SS concentrations increased by 1 to 2 times with DO reduction, implying the presence of more unsettled particles in the supernatant. Concomitantly, soluble proteins increased from less than 1 mg/L to up to 30 mg/L, and bound proteins decreased by more than 15% under DO limitation. Further enzymatic tests confirmed that, compared with polysaccharides, proteins were more involved in preventing sludge deflocculation. The DO stress also caused significant changes in the bulk concentrations of K+ and Ca2+; K+ increased by 40% and Ca2+ decreased by 30%. When the DO concentration was restored after 6 hours, reversible changes were observed in supernatant turbidity and SS, and concentrations of EPS proteins and cations, indicating a possible physiological response of microorganisms to a short-term low DO disturbance.

Reoxygenation Rate for Airlift Inner Circulation Reactor

2013 ◽  
Vol 726-731 ◽  
pp. 1926-1929
Author(s):  
Ke Wu Pi ◽  
Min Xia ◽  
Shi Shi ◽  
Qu Xiao
Keyword(s):  
Dissolved Oxygen ◽  
Aeration Rate ◽  
Airlift Reactor ◽  
Liquid Level ◽  
Aeration Tank ◽  
Do Concentration

Airlift inner circulation reactor (AICR) consisting of beaker and built-in aeration tank was introduced in this paper. The Dissolved oxygen recovery (RDO) was highly influenced by the ratios of the height of built-in aeration tank to the height of liquid level in reactor (Rh/H), the diameter of built-in aeration tank to the diameter of the reactor (Rd/D) and aeration rate (QN). Average RDO of 24.25 m.gm-3.s-s and DO concentration of 8.97mg.l-1 were obtained at Rd/D=0.47, Rh/H=0.68 and QN =1.0m3.m-3.min-1 for aerating 370s at 17°C. The total transferred oxygen in 4L deoxidized water reached 35.89mg, which had an increase by 11.15% than that of the traditional airlift reactor (AR). The DO concentration was 88.33-9.34mg.l-1 for AICR, but it’s only 7.71-8.58mg.l-1 for AR.

An investigation into studying of the activated sludge foaming potential by using physicochemical parameters

2002 ◽  
Vol 46 (1-2) ◽  
pp. 525-528 ◽  
Author(s):  
K. Hladikova ◽  
I. Ruzickova ◽  
P. Klucova ◽  
J. Wanner
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Physicochemical Parameters ◽  
Wastewater Treatment Plants ◽  
Physicochemical Characteristics ◽  
Full Scale ◽  
Aeration Tank ◽  
Foam Formation ◽  
Individual Parameter

This paper examines how the physicochemical characteristics of the solids are related to foam formation and describes how the foaming potential of full-scale plants can be assessed. The relations among activated sludge and biological foam hydrophobicity, scum index, aeration tank cover and filamentous population are evaluated. Individual parameter comparison reveals the scumming intensity can be estimated only on the assumption that foams is already established. None of the above mentioned characteristics can be reliably used to predict the foaming episodes at wastewater treatment plants.

scholarly journals Dissolved Oxygen Forecasting in Aquaculture: A Hybrid Model Approach

2020 ◽  
Vol 10 (20) ◽  
pp. 7079
Author(s):  
Elias Eze ◽  
Tahmina Ajmal
Keyword(s):  
Dissolved Oxygen ◽  
Mean Square Error ◽  
Short Term Memory ◽  
Sensor Data ◽  
Percentage Error ◽  
Forecasting Model ◽  
Mean Square ◽  
Intrinsic Mode Functions ◽  
Short Term ◽  
Do Concentration

Dissolved oxygen (DO) concentration is a vital parameter that indicates water quality. We present here DO short term forecasting using time series analysis on data collected from an aquaculture pond. This can provide the basis of data support for an early warning system, for an improved management of the aquaculture farm. The conventional forecasting approaches are commonly characterized by low accuracy and poor generalization problems. In this article, we present a novel hybrid DO concentration forecasting method with ensemble empirical mode decomposition (EEMD)-based LSTM (long short-term memory) neural network (NN). With this method, first, the sensor data integrity is improved through linear interpolation and moving average filtering methods of data preprocessing. Next, the EEMD algorithm is applied to decompose the original sensor data into multiple intrinsic mode functions (IMFs). Finally, the feature selection is used to carefully select IMFs that strongly correlate with the original sensor data, and integrate into both inputs for the NN. The hybrid EEMD-based LSTM forecasting model is then constructed. The performance of this proposed model in training and validation sets was compared with the observed real sensor data. To obtain the exact evaluation accuracy of the forecasted results of the hybrid EEMD-based LSTM forecasting model, four statistical performance indices were adopted: mean absolute error (MAE), mean square error (MSE), root mean square error (RMSE), and mean absolute percentage error (MAPE). Results are presented for the short term (12-h) and the long term (1-month) that are encouraging, indicating suitability of this technique for forecasting DO values.

scholarly journals High Dissolved Oxygen Selection againstNitrospiraSublineage I in Full-Scale Activated Sludge

2019 ◽  
Vol 53 (14) ◽  
pp. 8157-8166 ◽  
Author(s):  
Yingyu Law ◽  
Artur Matysik ◽  
Xueming Chen ◽  
Sara Swa Thi ◽  
Thi Quynh Ngoc Nguyen ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Full Scale

Optimisation and Uprating of Activated Sludge Plants by Efficient Process Design

1988 ◽  
Vol 20 (4-5) ◽  
pp. 121-132 ◽  
Author(s):  
B. Chambers ◽  
G. L. Jones
Keyword(s):  
Mathematical Model ◽  
Activated Sludge ◽  
Plug Flow ◽  
Oxygen Demand ◽  
Full Scale ◽  
Aeration Tank ◽  
Effluent Quality ◽  
Integration Techniques ◽  
In Series ◽  
The Uk

Requirements to improve effluent quality and reduce operating costs at existing activated sludge plants in the UK have led to the development of an accurate mathematical model of the process which can be used for full-scale design. The WRc Activated Sludge Model has been developed over a number of years and is based on the concept of describing the kinetics of BOD removal by including a Monod term for growth and a Michaelis-Menten term for enzymatic activity. Since the first formulation of the model, further equations have been added which describe the use of oxygen and nitrate as electron acceptors for the conversion of BOD. The model equations can be used to predict the performance of most configurations of the activated sludge process by using the ‘tanks in series' concept to describe aeration tank mixing characteristics. Solutions to the equations are easily obtained by standard numerical integration techniques using a computer. The software has been written in such a way that the model can be used interactively by a plant designer. Results obtained using the mathematical model have been used to redesign several full-scale activated sludge plants in the UK. In some cases, it has been possible to reduce the energy costs for aeration by 40% whilst maintaining effluent quality by accurately matching the supply of oxygen to the spatially-varying oxygen demand in plug-flow aeration tanks. Bulking sludge problems have also been solved by the conversion of completely-mixed aeration tanks to plug-flow aeration tanks with complementary redesign of the aeration system.

A full-scale operation of a novel activated sludge process without excess sludge production

1996 ◽  
Vol 34 (3-4) ◽  
pp. 395-404 ◽  
Author(s):  
H. Yasui ◽  
K. Nakamura ◽  
S. Sakuma ◽  
M. Iwasaki ◽  
Y. Sakai
Keyword(s):  
Activated Sludge ◽  
Inorganic Compounds ◽  
Material Balance ◽  
Full Scale ◽  
Aeration Tank ◽  
Total Biomass ◽  
Activated Sludge Process ◽  
Excess Sludge ◽  
Conventional Activated Sludge ◽  
Operation Costs

The authors have presented a new concept of excess sludge elimination treatment with recirculation of sludge via ozonation in the activated sludge process. This paper is intended to clarify the potential application of the process to municipal and industrial wastewater treatments. In a full-scale operational experiment lasting 10 months under 550 kg/d of BOD loading, no excess sludge was needed to be withdrawn and no significant accumulation of inorganic solids occurred in the aeration tank. Most of the inorganic compounds in the sludge were released to the soluble phase. Material balance indicated that one-third of ozonated sludge was mineralized via the recirculation treatment, and thereby the requirement of sludge mass to be treated was 3.3 times as much as sludge to be eliminated. Effluent TOC was slightly higher than under the conventional activated sludge process, indicating that refractory TOC was released from the sludge eliminated by treatment. The amount of released TOC corresponded to less than 2 weight % of eliminated sludge under recirculation rates below 30% of total biomass in the aeration tank in a day, but increased at higher recirculation rates. The operation costs associated with the process were estimated to be lower than those of conventional dewatering and disposal.

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