Relationship for Clarification Efficiency of Circular Secondary Clarifiers

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2539-2542 ◽  
Author(s):  
N. S. Voutchkov
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Full Scale ◽  
Solids Concentration

This paper discusses a regression-based model describing clarification efficiency of circular activated sludge secondary clarifiers. Surface overflow rate was found to be well correlated with effluent suspended solids, sidewater depth and settled sludge volume at three full scale wastewater treatment plants during a six month study. Relationship was verified to be sufficiently accurate for prediction of effluent suspended solids concentration over a six month period at another three treatment plants.

Performance of activated sludge diffusion for biological treatment of hydrogen sulphide gas emissions

2013 ◽  
Vol 68 (9) ◽  
pp. 1932-1939 ◽  
Author(s):  
Vera L. Barbosa ◽  
Richard M. Stuetz
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Hydrogen Sulphide ◽  
Biological Treatment ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Broad Application ◽  
H2s Removal ◽  
Treatment Performance ◽  
Solids Concentration

Odours from wastewater treatment plants are comprised of a mixture of various gases with hydrogen sulphide (H2S) often being the dominant constituent. Activated sludge diffusion (ASD) as a biotreatment system for odour abatement has been conducted for over 30 years but has limited broad application due to disagreement in the literature regarding the effect that ASD may have on wastewater treatment performance. The effects of continuous H2S diffusion at 25 ppmv, with weekly peaks of approximately 100 ppmv, on H2S removal efficiency and wastewater treatment performance was evaluated over a 2-month period using an activated sludge pilot plant. H2S removal averaged 100% during diffusion at 25 ppmv, and 98.9% during the 100 ppmv peak periods. A significant increase in mixed liquor volatile suspended solids concentration (P < 0.01) was observed during H2S diffusion, which may be due to an increase in H2S-degrading microorganisms. There was no adverse effect of H2S on nitrification throughout the ASD trials. Ammonia (NH3) removal was slightly better in the test receiving H2S diffusion (87.6%) than in the control (85.4%). H2S diffusion appeared to improve robustness of the AS biomass to operational upsets.

Evaluating the treatment performance of a full scale Activated Sludge Plant in Islamabad, Pakistan

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
S. S. Fatima ◽  
S. Jamal Khan
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Full Scale ◽  
Operational Parameter ◽  
Mixed Liquor ◽  
Treatment Performance

In this study, the performance of wastewater treatment plant located at sector I-9 Islamabad, Pakistan, was evaluated. This full scale domestic wastewater treatment plant is based on conventional activated sludge process. The parameters which were monitored regularly included total suspended solids (TSS), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). It was found that the biological degradation efficiency of the plant was below the desired levels in terms of COD and BOD. Also the plant operators were not maintaining consistent sludge retention time (SRT). Abrupt discharge of MLSS through the Surplus Activated sludge (SAS) pump was the main reason for the low MLSS in the aeration tank and consequently low treatment performance. In this study the SRT was optimized based on desired MLSS concentration between 3,000–3,500 mg/L and required performance in terms of BOD, COD and TSS. This study revealed that SRT is a very important operational parameter and its knowledge and correct implementation by the plant operators should be mandatory.

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 The Microbial Database for Danish wastewater treatment plants with nutrient removal (MiDas-DK) – a tool for understanding activated sludge population dynamics and community stability

2013 ◽  
Vol 67 (11) ◽  
pp. 2519-2526 ◽  
Author(s):  
A. T. Mielczarek ◽  
A. M. Saunders ◽  
P. Larsen ◽  
M. Albertsen ◽  
M. Stevenson ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Wastewater Treatment Plants ◽  
Amplicon Sequencing ◽  
Temporal Variations ◽  
Full Scale ◽  
16S Rrna Amplicon Sequencing ◽  
Specific Factors ◽  
Operational Data

Since 2006 more than 50 Danish full-scale wastewater treatment plants with nutrient removal have been investigated in a project called ‘The Microbial Database for Danish Activated Sludge Wastewater Treatment Plants with Nutrient Removal (MiDas-DK)’. Comprehensive sets of samples have been collected, analyzed and associated with extensive operational data from the plants. The community composition was analyzed by quantitative fluorescence in situ hybridization (FISH) supported by 16S rRNA amplicon sequencing and deep metagenomics. MiDas-DK has been a powerful tool to study the complex activated sludge ecosystems, and, besides many scientific articles on fundamental issues on mixed communities encompassing nitrifiers, denitrifiers, bacteria involved in P-removal, hydrolysis, fermentation, and foaming, the project has provided results that can be used to optimize the operation of full-scale plants and carry out trouble-shooting. A core microbial community has been defined comprising the majority of microorganisms present in the plants. Time series have been established, providing an overview of temporal variations in the different plants. Interestingly, although most microorganisms were present in all plants, there seemed to be plant-specific factors that controlled the population composition thereby keeping it unique in each plant over time. Statistical analyses of FISH and operational data revealed some correlations, but less than expected. MiDas-DK (www.midasdk.dk) will continue over the next years and we hope the approach can inspire others to make similar projects in other parts of the world to get a more comprehensive understanding of microbial communities in wastewater engineering.

Increased performance of secondary clarifiers using dynamic distribution of minimum return sludge rates

2009 ◽  
Vol 60 (9) ◽  
pp. 2439-2445 ◽  
Author(s):  
A. Lynggaard-Jensen ◽  
P. Andreasen ◽  
F. Husum ◽  
M. Nygaard ◽  
J. Kaltoft ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Suspended Solids ◽  
Considerable Increase ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Total Flow ◽  
Equal Distribution ◽  
Solids Concentration ◽  
Hydraulic Load ◽  
And Control

Most wastewater treatment plants have several secondary clarifiers or even more sets of clarifiers including several secondary clarifiers, and in practice it is a well known problem that equal distribution of the load to the single clarifier (or set of clarifiers) is very difficult—not to say impossible—to obtain. If the problem is neglected, quite a big percentage of the total clarifier capacity—measured as the max. allowed hydraulic load—can be lost. Further, return sludge rates are seldom controlled by any other means than as a (typically too high) percentage of the inlet to the wastewater treatment plant—giving a varying and too low suspended solids concentration in the return sludge, which again can lead to an unnecessary use of polymer in the pre-dewatering of the surplus sludge taken from the return sludge. A control of the return sludge rate divided into two parts - control of the total return sludge flow and control of how the total flow shall be distributed between the secondary clarifiers - is able to solve the mentioned problems. Finally, as shall be demonstrated on full scale wastewater treatment plants, a considerable increase of the hydraulic capacity of the treatment plants can be obtained.

scholarly journals Reliability of removal of selected pollutants in different technological solutions of household wastewater treatment plants

2017 ◽  
Vol 35 (1) ◽  
pp. 141-148 ◽  
Author(s):  
Michał Marzec
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Total Suspended Solids ◽  
Hybrid Reactor ◽  
Limit Values

AbstractThe reliability of removal of selected contaminants in three technological solutions of the household sewage treatment plants was analysed in this paper. The reliability of the sewage treatment plant with activated sludge, sprinkled biological deposit and hybrid reactor (activated sludge and immersed trickling filter) was analyzed. The analysis was performed using the Weibull method for basic indicators of impurities, BOD5, COD and total suspended solids. The technological reliability of the active sludge treatment plant was 70% for BOD5, 87% for COD and 66% for total suspended solids. In the sewage treatment plant with a biological deposit, the reliability values determined were: 30% (BOD5), 60% (COD) and 67% (total suspended solids). In a treatment plant with a hybrid reactor, 30% of the BOD5and COD limit values were exceeded, while 30% of the total suspended solids were exceeded. The reliability levels are significantly lower than the acceptable levels proposed in the literature, which means that the wastewater discharged from the analysed wastewater treatment plants often exceeds the limit values of indicators specified in currently valid in Poland Regulation of the Minister of Environment for object to 2000 population equivalent.

scholarly journals Quantification of biologically and chemically bound phosphorus in activated sludge from full-scale plants with biological P-removal

2021 ◽  
Author(s):  
Francesca Petriglieri ◽  
Jette F. Petersen ◽  
Miriam Peces ◽  
Marta Nierychlo ◽  
Kamilla Hansen ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Mass Balance ◽  
Wastewater Treatment Plants ◽  
Raman Microspectroscopy ◽  
Full Scale ◽  
P Fractions ◽  
P Content ◽  
Total P ◽  
P Removal

AbstractLarge amounts of phosphorus (P) are present in activated sludge from municipal wastewater treatment plants, where it exists in the form of metal salt precipitates or biologically bound into the biomass as nucleic acids, cell membrane components, and the extracellular polymeric substances or, in special polyphosphate-accumulating organisms (PAOs), as intracellular polyphosphate. Only recently, methods that reliably allow an absolute quantification of the different P-fractions, such as sequential extraction, Raman microspectroscopy, solid-state 31P magic angle spinning (MAS) NMR, and solution state 31P NMR have been developed. This study combines these techniques to obtain a comprehensive P mass-balance of activated sludge from four wastewater treatment plants with enhanced biological phosphate removal (EBPR). The total content of P and various cations was measured by chemical analysis (ICP-OES), and different P fractions were extracted for chemical characterization. Chemically bound P constituted 38-69% of total P, most likely in the form of Fe, Mg, or Al minerals, while organically bound P constituted 7-9%. By using Raman microspectroscopy and solution state 31P NMR and 31P MAS NMR spectroscopy before and after anaerobic P-release experiments, poly-P was quantified and constituted 22-54% of total P in the activated sludges and was found in approx. 25% of all bacterial cells. Moreover, Raman microspectroscopy in combination with fluorescence in situ hybridization (FISH) was used to quantify the species-specific intracellular poly-P of known PAO genera (Tetrasphaera, Ca. Accumulibacter, Dechloromonas) and other microorganisms known to possess high level of poly-P, such as the filamentous Ca. Microthrix. They were all abundant, as measured by quantitative-FISH and amplicon sequencing, and accumulated large amount of poly-P, depending on their cell-size, contributing substantially to the P-removal. Interestingly, in all four EBPR plants investigated, only 1-13% of total poly-P was stored by unidentified PAO, highlighting that most PAOs in the full-scale EBPR plants investigated are now known.HighlightsExhaustive P mass-balance of main organic and inorganic P-species in four EBPR plantsQuantification of poly-P of FISH-defined PAO and other species with high P contentTotal P content was 36-50 mgP/gSS of which 31-62% was in biomass and as poly-PA high fraction of all cells (25-30%) contained a high content of poly-PKnown PAOs contained almost all poly-P in the EBPR plants investigated

Abundance of amoA genes of ammonia-oxidizing archaea and bacteria in activated sludge of full-scale wastewater treatment plants

2011 ◽  
Vol 102 (4) ◽  
pp. 3694-3701 ◽  
Author(s):  
Tawan Limpiyakorn ◽  
Puntipar Sonthiphand ◽  
Chaiwat Rongsayamanont ◽  
Chongrak Polprasert
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Full Scale ◽  
Ammonia Oxidizing Archaea
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