The impact of phosphorus deficiency on nitrification - case study of a biological pretreatment plant for rendering plant effluent

1996 ◽  
Vol 34 (1-2) ◽  
pp. 229-236 ◽  
Author(s):  
O. Nowak ◽  
K. Svardal ◽  
H. Kroiss
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Phosphorus Deficiency ◽  
Extended Model ◽  
Biological Pretreatment ◽  
Dynamic Conditions ◽  
Low Levels ◽  
The Impact ◽  
Kinetics Of

The highly concentrated wastewater of a rendering plant (7 g COD/l and 1.1 g TKN/l on average) is biologically pretreated in an activated sludge plant. Due to low loading of this plant, full nitrification and nitrogen removal are generally achieved. In periods of high COD loads, however, the nitrification capacity was substantially reduced. Control analyses revealed extreme phosphorus deficiency and that only nitrite, but no nitrate was formed. An extended model based on the ‘Activated sludge model No. 1’ has been used to investigate the kinetics of nitrification in the case of phosphorus deficiency, the demand for phosphorus under dynamic conditions, as well as the effect of variations in the nitrogen load at low levels of phosphate.

Evaluation of extracellular biopolymer and its impact on bioflocculation in activated sludge bioreactors

2011 ◽  
Vol 63 (4) ◽  
pp. 689-694 ◽  
Author(s):  
G. A. C. Ehlers ◽  
S. J. Turner
Keyword(s):  
Activated Sludge ◽  
Cell Attachment ◽  
Negative Impact ◽  
Extracellular Polysaccharide ◽  
Continuous Systems ◽  
Biological Processes ◽  
Reactor Operation ◽  
Low Levels ◽  
Sludge Settling ◽  
The Impact

The influence and dynamics of bacterial extracellular polysaccharide (EPS) polymer production and its impact on bioflocculation in activated sludge (AS) bench-scale reactors were investigated. The impact of food to microorganism ratio (F/M), reactor configuration and easily biodegradable carbohydrates in influent streams on biological processes that support or weaken good floc formation and the link with EPS quantity was studied. Bioreactors were run as either sequencing batch or continuous systems using wastewater media with glucose or acetate as C source in different F/M ratios. EPS levels were quantified using mid-infrared spectroscopy which provided a rapid technique for monitoring biological processes within AS WWTP. The analysis revealed an interdependent link between EPS production, sludge settling characteristics and mode of reactor operation. An inverse relationship between F/M ratios and EPS quantities was seen but a positive link between EPS levels and aggregation indices, a measure of the efficiency of inter cell attachment and which indicates good settling properties, was also seen. This indicates that during high F/M conditions in lab-scale AS reactors, low levels of EPS may be produced which could have a negative impact on settling of the biomass. Floc architecture was examined under the microscope. Transient growth of filamentous bacteria was seen in the reactors.

Sewage-treatment under substantial load variations in winter tourism areas – a full case study

2004 ◽  
Vol 50 (7) ◽  
pp. 147-155 ◽  
Author(s):  
S. Winkler ◽  
N. Natsché ◽  
T. Gamperer ◽  
M. Dum
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Nutrient Removal ◽  
Sewage Treatment ◽  
Activated Sludge Process ◽  
Two Stage ◽  
Winter Tourism ◽  
Load Variations ◽  
Sudden Load

The sewage-load variations in winter tourism areas are characterized by sudden increases - in the ange of a factor two to three - within only a few days at the start and the end of the tourist season, especially at Christmas. The sudden load increases occur during periods of low wastewater temperatures, which is an additional demanding factor with respect to nitrogen removal. A full case study was carried out at WWTP Saalfelden, which is located near one of Austria's largest skiing resorts. The plant is designed for 80,000 PE and built according to the HYBRID®-concept, which is a special two stage activated sludge process for extensive nutrient removal.

Activated sludge system modelling and simulations for improving the effluent water quality

1999 ◽  
Vol 39 (8) ◽  
pp. 93-98 ◽  
Author(s):  
Chia-Yau Cheng ◽  
Irina Ribarova
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Treatment Plant ◽  
Biological Nitrogen Removal ◽  
System Modelling ◽  
Extended Model ◽  
Conventional Activated Sludge ◽  
Activated Sludge System ◽  
Biological Nitrogen ◽  
Parameter Values

This paper describes the results from a study carried out to investigate the feasibility of upgrading Parada wastewater treatment plant (WWTP) for biological nitrogen removal. The biological treatment of Parada WWTP is a conventional activated sludge process. Since 1992 only one of the three available aeration tanks has been used. Activated Sludge Model No.1 was used as a base for modelling of the activated sludge system. To accomplish all the calculations, AQUASIM software was applied. The model was calibrated and verified with data from Parada WWTP operation. Very good correlations between measured data and simulation results were achieved using stoichiometric and kinetic parameter values proposed by the authors of IAWQ Model No. 1. However, characterisation of the actual wastewater was necessary. Computer simulations with a verified and extended model were done to study whether the capacity of the treatment plant is enough for biological nitrogen removal. Very high effluent quality can be achieved if the first tank volume is used for denitrification, the second and third tank volumes are used for BOD removal and nitrification, the recirculating effluent flow ratio is 1.5 and the sludge age is 15 days.

scholarly journals Do Knowledge and Experience Value Affect Green Tourism Activity Participation and Buying Decision? A Case Study of Natural Dyeing Experience in China

2021 ◽  
Vol 13 (15) ◽  
pp. 8579
Author(s):  
Xiaocheng Vicky Zhang ◽  
Suk Ha Grace Chan
Keyword(s):  
Purchase Intention ◽  
Structural Equation ◽  
Rapid Development ◽  
Sem Analysis ◽  
Extended Model ◽  
Natural Dyeing ◽  
Green Tourism ◽  
Tourism Activity ◽  
The Impact

With the rapid development of niche tourism, green tourism activity has become known to the wider public. By taking into account the extended theory of planned behaviour (TPB), this study takes natural dyeing experience as a case study, with the aim of determining the tourist purchase intention of green products under the destination experience scenario. A quantitative approach was adopted, and 349 valid sets of data were collected from individuals who have participated in natural dyeing activities. Partial least squares–structural equation modelling (PLS–SEM) analysis was conducted to test the conceptual model. The results indicate that experience value (EV) had a significant impact on green purchase conception and intention. In addition, subjective norm had a significant positive influence on tourism green purchase attitude. However, environmental knowledge failed to predict green purchase attitude and perceived behavioural control. The PLS–SEM analysis confirmed the extended TPB model, which showed relatively good predictive validity. Findings suggest that TPB mediated the relationship between EV and purchase intention. The extended model considerably contributes to improving understanding of the impact on green tourism products and dissects theoretical and practical implications to practitioners. Apart from strengthening the experience value from attaining, learning, escapism, and fantasy aspects, on the basis of previous literature, this study concludes that practically, environmental education regarding the experimental environment in tourism destinations in China should return to green activity itself and induce the support of green tourism products. Tourism marketers should trigger personal green knowledge through sense experience in the process of stimulating and promoting green tourism activities, as well as stimulate purchasing power.

“Power Is Sweet”

2020 ◽  
pp. 108-127
Author(s):  
Jonathan C. Pinckney
Keyword(s):  
Case Studies ◽  
Authoritarian Regime ◽  
Ordinary People ◽  
Civil Resistance ◽  
Political Outcomes ◽  
Low Levels ◽  
The Impact ◽  
Over Time

This chapter presents the second of three case studies of civil resistance transitions (CRTs) and the impact of the challenges of mobilization and maximalism in CRTs. The case examined is the transition in Zambia following the Movement for Multiparty Democracy’s campaign against Zambia’s one-party authoritarian regime. The case study finds that low levels of mobilization during the transition led to a lack of accountability for new leaders, facilitating an increase in corruption and derailing Zambia’s move to democracy. Instead the regime that has been consolidated over time is an elite semi-democracy, in which elites dominate the politics for their own benefit and ordinary people have little impact on political outcomes.

Treatment of mixed municipal and winery wastewaters in a conventional activated sludge process: a case study

2005 ◽  
Vol 51 (1) ◽  
pp. 89-98 ◽  
Author(s):  
M. Brucculeri ◽  
D. Bolzonella ◽  
P. Battistoni ◽  
F. Cecchi
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Oxidation Process ◽  
Treatment Plant ◽  
Main Process ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Conventional Activated Sludge Process ◽  
Denitrification Process

The possibility of co-treating municipal and winery wastewaters in a conventional activated sludge process was studied at full scale. The wastewater treatment plant considered in this paper operated an extended-oxidation process during vintage (four month per year) and a pre-denitrification/oxidation process during the rest of the year. The experimentation showed that good performances, in terms of COD and nitrogen removal, could be obtained in both cases: 90% and 60%, for COD and nitrogen removal, respectively. Thanks to the high solid retention times applied to the system (up to 48 days) the waste activated sludge production was low (0.20 kgMLVSS/kgCODremoved) and respiration was the main process for carbon removal. Nitrification was always satisfactory while the behaviour of the denitrification process during vintage was not totally understood and further studies are going on.

scholarly journals The Impact of Psychological Adjustment on Private University Students’ Academic Achievement: Case Study

2019 ◽  
Vol 8 (6) ◽  
pp. 184
Author(s):  
Moosa Jaafar Fateel
Keyword(s):  
Academic Achievement ◽  
University Students ◽  
Sample Size ◽  
Psychological Adjustment ◽  
Positive Impact ◽  
Private University ◽  
Low Levels ◽  
The Impact ◽  
Academic Specialization

The present study examined the impact of psychological adjustment on private university students’ academic achievement. The sample size consisted of 121 university students (42.1% male, and 57.9% female). The results showed that 34% of the students recorded low levels of psychological adjustment, 51 % of the students recorded average levels of psychological adjustment, 15 % of the students recorded high levels of psychological adjustment. The findings also indicated relationship between psychological adjustment and university academic achievement and that psychological adjustment has a significant positive impact on private university students’ academic achievement. The study concludes with suggesting to apply tests that measure students’ psychological adjustment with the specialization in which they wish to continue their university study in before accepting them in any academic specialization.

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