scholarly journals Performance evaluation and coefficients of reliability for waste stabilization ponds in northeast Brazil

Author(s):  
Matheus Sales Alves ◽  
Fernando José Araújo da Silva ◽  
André Luís Calado Araújo ◽  
Erlon Lopes Pereira

This paper assesses the reliability of Waste Stabilization Ponds (WSP) and proposes an alternative approach to WSP design based on the calculation of coefficient of reliability (COR) from an acceptable measure of violation of discharge standards. For that, data were collected from 10 full-scale systems operating in Northeast Brazil. All systems receive predominantly domestic effluent and are composed of one facultative pond and two serial maturation ponds. Different levels of restriction for effluent discharge were considered regarding the parameters: BOD, COD, total suspended solids, ammonia and thermotolerant coliforms. The Log-normal Probability Distribution Function (PDF) was able to represent the behavior of the concentration data in the effluent and, therefore, allowed the COR calculation. The COR was obtained from the coefficient of variation (CV) of the concentrations and the standardized normal variable associated with a 95% probability of non-exceedance. The observed dispersion of the results proved to be detrimental to the adoption of a single COR value for the evaluated parameters. In addition, the comparison between observed and design/operational concentration for optimal performance showed that the 95% reliability scenario represents a less achievable target for WSP systems.

1986 ◽  
Vol 18 (10) ◽  
pp. 31-35 ◽  
Author(s):  
J. I. Oragui ◽  
T. P. Curtis ◽  
S. A. Silva ◽  
D. D. Mara

The removal of excreted bacteria (faecal coliforms, faecal streptococci, Clostridium perfringens, total and sorbitol-fermenting bifidobacteria, salmonellae and thermophilic campylobacters) and viruses (enterovirus and rotavirus) in a series of deep anaerobic, facultative and maturation ponds (depth range: 2.8 - 3.4 m), with an overall retention time of 21 days and a mean mid-depth temperature of 27°C, was studied. Thermophilic campylobacters, bifidobacteria and salmonellae were not detected after 11, 16 and 21 days' retention respectively. Faecal coliforms, faecal streptcocci and Cl. perfringens were reduced by 4, 4 and 2 orders of magnitude respectively, and enteroviruses and rotaviruses both by 3 orders. The results indicate that pathogen removal in deep ponds is similar to that in ponds of normal depth.


1987 ◽  
Vol 19 (3-4) ◽  
pp. 569-573 ◽  
Author(s):  
J. I. Oragui ◽  
T. P. Curtis ◽  
S. A. Silva ◽  
D. D. Mara

The removal of excreted bacteria (faecal coliforms, faecal streptococci, Clostridium perfringens, total and sorbitol-fermenting bifidobacteria, salmonellae and thermophilic campylobacters) and viruses (enterovirus and rotavirus) in a series of deep anaerobic, facultative and maturation ponds (depth range: 2.8 - 3.4 m), with an overall retention time of 21 days and a mean mid-depth temperature of 27°C, was studied. Thermophilic campylobacters, bifidobacteria and salmonellae were not detected after 11, 16 and 21 days' retention respectively. Faecal coliforms, faecal streptcocci and Cl. perfringens were reduced by 4, 4 and 2 orders of magnitude respectively, and enteroviruses arid rotaviruses both by 3 orders. The results indicate that pathogen removal in deep ponds is similar to that in ponds of normal depth.


1993 ◽  
Vol 27 (4) ◽  
pp. 727-728 ◽  
Author(s):  
J.I. Oragui ◽  
Helen Arridge ◽  
D.D. Mara ◽  
H.W. Pearson ◽  
S.A. Silva

1995 ◽  
Vol 31 (12) ◽  
pp. 285-290 ◽  
Author(s):  
J. I. Oragui ◽  
H. Arridge ◽  
D. D. Mara ◽  
H. W. Pearson ◽  
S. A. Silva

Rotavirus removal in waste stabilization ponds is a relatively slow process: in a series of ten ponds (a 1-d anaerobic pond followed by nine 2-d ponds) its numbers were reduced from 1.4 × 105 per litre to zero, and in an “innovative” series (a 1-day anaerobic pond, 3-d facultative pond, 3.8-d, 3-d and 5-d maturation ponds) from 5.1 × 104 per litre to <5 per litre. Faecal coliforms were better indicators of rotaviruses than was Clostridium perfringens .


1995 ◽  
Vol 31 (12) ◽  
pp. 91-101 ◽  
Author(s):  
Y. Racault ◽  
C. Boutin ◽  
A. Seguin

In 1992, a survey was conducted on the performance of waste stabilization ponds in France. The data selected come from a sample of 178 ponds, with an average capacity of 600 p.e., throughout France. For each plant, one or several input--output load measurements over a 24-h period are available. The average organic load level received is approximately 25 kg BOD/ha.d, representing 50% of the nominal load. The quality of the treated water is presented based on the type of sewerage system feeding the ponds. The results appear dispersed, however; in 70% of the cases the concentrations in COD and BOD on filtered samples are under 120 mg/l and 40 mg/l, respectively, and the concentration in TSS under 120 mg/l (discharge standards in France for waste stabilization ponds). The reductions in nitrogen and phosphorus nutrients are on average from 60% to 70%. The influence of different parameters (sewerage system type, organic load, season, age of plant, etc.) was studied. The results appear noticeably worse when the ponds receive wastewater from a strictly separate sewerage system.


Heliyon ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. e06207
Author(s):  
Joshua N. Edokpayi ◽  
John O. Odiyo ◽  
Oluwaseun E. Popoola ◽  
Titus A.M. Msagati

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