Sludge accumulation and distribution impact the hydraulic performance in waste stabilisation ponds

2017 ◽  
Vol 110 ◽  
pp. 354-365 ◽  
Author(s):  
Liah X. Coggins ◽  
Marco Ghisalberti ◽  
Anas Ghadouani
Keyword(s):  
Hydraulic Performance ◽  
Waste Stabilisation Ponds ◽  
Sludge Accumulation

RTD (residence time distribution) predictions in large mechanically aerated lagoons

2007 ◽  
Vol 55 (11) ◽  
pp. 29-36 ◽  
Author(s):  
D. Stropky ◽  
K. Pougatch ◽  
P. Nowak ◽  
M. Salcudean ◽  
P. Pagoria ◽  
...  
Keyword(s):  
Paper Industry ◽  
Three Dimensional ◽  
Field Measurements ◽  
Particle Method ◽  
Practical Method ◽  
Hydraulic Performance ◽  
Computational Time ◽  
Complex Flow ◽  
Mechanical Agitation ◽  
Sludge Accumulation

Mechanically aerated lagoons (used for wastewater treatment in the pulp and paper industry) are typically very large (>500,000 m3) and have complex three-dimensional fluid flow patterns due to mechanical agitation, sludge accumulation, internal baffling, and confined inlet/outlet flow channels. RTD data is frequently used for evaluation of hydraulic performance. however, obtaining accurate data with traditional dye measurements is a difficult and time-consuming process. Moreover, the mixing impact of factors such as aerator positions, sludge accumulation, and internal baffles would require a significant and costly number of local field measurements. Recent applications of CFD to mechanically aerated lagoons have helped engineers to understand the complex flow interactions. This paper provides a practical method for the evaluation of the hydraulic performance of large mechanically aerated lagoons using CFD. A method, based on random-walk Lagrangian particle tracking, has been developed to significantly shorten the computational time needed to produce RTD curves for these lagoons. Comparison of the particle method with the more conventional scalar transport yields excellent results. These methods allow wastewater engineers to combine their existing knowledge and expertise with the established power of CFD. The results quantify the hydraulic impact of different inlet/outlet configurations, aerator configurations, influent flow rates, and bottom sludge profiles.

RELAÇÃO VAZÃO x PRESSÃO EM MICROASPERSORES DAN 2001 SOB CONDIÇÃO ADVERSA DE OPERAÇÃO

Irriga ◽  
2003 ◽  
Vol 8 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Marco Antonio Fonseca Conceição ◽  
Rubens Duarte Coelho
Keyword(s):  
Hydraulic Performance ◽  
Sao Paulo ◽  
The Self ◽  
São Paulo ◽  
Flow Curves ◽  
Pressure Flow ◽  
Adverse Condition ◽  
Irrigation Time ◽  
E Mail ◽  
Stable Flow

RELAÇÃO VAZÃO x PRESSÃO EM MICROASPERSORES DAN 2001 SOB CONDIÇÃO ADVERSA DE OPERAÇÃO  Marco Antônio Fonseca ConceiçãoEmbrapa Uva e Vinho, Estação Experimental de Jales, Jales, SP. CP 241. CEP 15700-000.E-mail: [email protected] Duarte CoelhoDepartamento de Engenharia Rural, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, SP. CP 09, CEP 13418-900.E-mail: [email protected]  1 RESUMO  Alguns microaspersores possuem membranas que regulam a sua pressão de operação, mantendo a vazão praticamente estável dentro de uma faixa de pressão na rede hidráulica. Operadores de irrigação no campo, muitas vezes com baixo nível de instrução e sem orientação profissional qualificada, visando reduzir problemas de entupimento ou para diminuir o tempo de irrigação, costumam retirar as membranas autocompensantes para aumentar a vazão do emissores, o que pode comprometer o desempenho hidráulico do sistema. Para avaliar o efeito da retirada da membrana  sobre as vazões dos microaspersores, no presente trabalho determinou-se as relações entre pressão e vazão para sete bocais do microaspersor DAN 2001, operando na ausência da membrana autocompensante. As curvas pressão-vazão sem as membranas autocompensantes apresentaram comportamento potencial com expoentes variando entre 0,58 e 0,64. As vazões dos microaspersores sem as membranas aumentaram de forma inversamente proporcional aos diâmetros dos emissores, quando comparadas às vazões nominais com as membranas.  UNITERMOS: Hidráulica, irrigação, microaspersão.  CONCEIÇÃO, M.A.F.; COELHO, R.D. FLOW X PRESSURE RELATIONSHIP FOR DAN 2001 MICROSPRINKLERS UNDER ADVERSE CONDITION  2 ABSTRACT  Many types of microsprinklers have a self-compensating membrane to regulate their pressure, keeping a stable flow. Many producers usually take the membranes off to reduce clogging problems  or irrigation time. This procedure could endanger the system hydraulic performance. To evaluate the effect of taking off the self-compensating membrane from microsprinklers it was determined, in the present work, the pressure-flow relationship for seven Dan 2001 microsprinkler nozzles operating without the membrane. The pressure-flow curves presented a potential behavior with the exponents varying from 0.58 to 0.64. Microsprinkler flows without the membranes increased inversely proportional to the emitter diameters, comparing to the nominal flows using the membranes.  KEYWORDS: Hydraulic, irrigation, microsprinkler.

Occurrence and Removal of Cryptosporidium spp. Oocysts and Giardia spp. Cysts in Kenyan Waste Stabilisation Ponds

1993 ◽  
Vol 27 (3-4) ◽  
pp. 97-104 ◽  
Author(s):  
A. M. Grimason ◽  
H. V. Smith ◽  
W. N. Thitai ◽  
P. G. Smith ◽  
M. H. Jackson ◽  
...  
Keyword(s):  
Waste Water ◽  
Water Samples ◽  
Laboratory Experiments ◽  
Municipal Waste ◽  
Retention Period ◽  
Waste Stabilisation Ponds ◽  
Cryptosporidium Spp ◽  
Physico Chemical ◽  
Microbiological Parameters ◽  
Final Effluent

This study was designed to determine tlie occurrence and removal of Cryptosporidium spp. oocysts and Giardia spp. cysts, in municipal waste-water by waste stabilisation ponds in tlie Republic of Kenya. Eleven waste stabilisation pond systems located in towns across Kenya were included. A total of 66 waste-water samples were examined for the presence of oocysts and cysts, comprising 11 raw waste-water and 55 pond effluent samples over a two month period. Cryptosporidium spp. oocysts were detected in 6 and Giardia spp. cysts in 9 of the designated pond systems analysed demonstrating their ubiquitous nature throughout Kenya. Oocyst levels detected in raw waste-water samples ranged from 12.5 - 72.97 oocysts/l and various pond effluents between 2.25 - 50 oocysts/l. Cyst levels detected in raw waste-water samples ranged from 212.5 to 6212.5 cysts/l and in various pond effluents from 3.125 to 230.7 cysts/l. No Cryptosporidium spp. oocysts were detected in the final effluent from any pond systems studied (11/11). Whereas no Giardia spp. cysts were detected in the final effluent from 10 of 11 waste stabilisation pond systems studied, one pond system was found to be consistently discharging cysts in the final effluent at concentrations ranging from 40 to 50 cysts/l. The minimum retention period for the removal of Cryptosporidium spp. oocysts and Giardia spp. cysts was 37.3 days. Laboratory experiments were performed to assess physico-chemical and microbiological parameters to express relationships between pond performance and protozoa removal.

scholarly journals Two-Dimensional Numerical Modeling of Flow in Physical Models of Rock Vane and Bendway Weir Configurations

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 458
Author(s):  
Drew C. Baird ◽  
Benjamin Abban ◽  
S. Michael Scurlock ◽  
Steven B. Abt ◽  
Christopher I. Thornton
Keyword(s):  
Numerical Modeling ◽  
Physical Model ◽  
Numerical Models ◽  
Hydraulic Performance ◽  
Physical Models ◽  
Protection Measures ◽  
Design Engineers ◽  
Model Study ◽  
Study Results ◽  
Wide Range

While there are a wide range of design recommendations for using rock vanes and bendway weirs as streambank protection measures, no comprehensive, standard approach is currently available for design engineers to evaluate their hydraulic performance before construction. This study investigates using 2D numerical modeling as an option for predicting the hydraulic performance of rock vane and bendway weir structure designs for streambank protection. We used the Sedimentation and River Hydraulics (SRH)-2D depth-averaged numerical model to simulate flows around rock vane and bendway weir installations that were previously examined as part of a physical model study and that had water surface elevation and velocity observations. Overall, SRH-2D predicted the same general flow patterns as the physical model, but over- and underpredicted the flow velocity in some areas. These over- and underpredictions could be primarily attributed to the assumption of negligible vertical velocities. Nonetheless, the point differences between the predicted and observed velocities generally ranged from 15 to 25%, with some exceptions. The results showed that 2D numerical models could provide adequate insight into the hydraulic performance of rock vanes and bendway weirs. Accordingly, design guidance and implications of the study results are presented for design engineers.

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