Evaluation of a package plant for small communities in Mexico

2002 ◽  
Vol 2 (4) ◽  
pp. 145-150
Author(s):  
T. Pavón Silva ◽  
S.G. Hoyos ◽  
C. Chávez Guerra
Keyword(s):  
Water Quality ◽  
Scientific Explanation ◽  
Small Communities ◽  
Sedimentation Process

The design and operation of floc blanket clarification plant, embodying coagulation, flocculation and floc blanket sedimentation is still very much an art, mainly because there has been no adequate scientific explanation of the mechanisms of the floc blanket sedimentation process. This study aims to provide an explanation based on the floc blanket formation with CPL (hydroxyl chlorine of aluminium) coagulant. The theoretical parameters results were: Gcoagulation: 1,500 s-1; Gflocculation: 397 s-1, and for sedimentation G×θ×c 2476.8. The solid removal in the floc blanket was 65.28% expressed by residual turbidity. The water quality obtained at the end of the treatment satisfied the values of official Mexican standards.

Comparative Study of Dissolved Air Flotation and Sedimentation Process for Treating Reservoir Water with Low Temperature, Low Turbidity and High Natural Organic Matter

2011 ◽  
Vol 71-78 ◽  
pp. 2767-2771 ◽  
Author(s):  
Jing Zou ◽  
Jun Tao Zhu ◽  
Chao Pan ◽  
Jun Ma
Keyword(s):  
Water Quality ◽  
Low Temperature ◽  
Bubble Column ◽  
Reservoir Water ◽  
Dissolved Air Flotation ◽  
Sedimentation Process ◽  
Air Flotation ◽  
Better Than ◽  
Glass Bubble ◽  
Dissolved Air

In this research, the dissolved air flotation (DAF) were tried to treat drinking water to replace traditional sedimentation technology. Experimental study of sedimentation process and DAF was carried out in a jet tester and a glass bubble column respectively. The experimental results demonstrated that the indicators of water quality such as turbidity, chromaticity and CODMn after two processes decreased firstly and then increased with the PAC-dose increasing, and 7.41 mg Al L-1 was the optimum PAC dosage. Moreover, with the optimum PAC dosage, water quality after DAF proved much better than that after sedimentation process. As a result, DAF is a more effective technology to treat the reservoir water with low temperature, low turbidity and high NOM.

scholarly journals Riverbank Filtration Impacts on Post Disinfection Water Quality in Small Systems—A Case Study from Auburn and Nebraska City, Nebraska

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1865
Author(s):  
Matteo D'Alessio ◽  
Bruce Dvorak ◽  
Chittaranjan Ray
Keyword(s):  
Water Quality ◽  
Distribution System ◽  
Disinfection Byproducts ◽  
Riverbank Filtration ◽  
Small Systems ◽  
Small Communities ◽  
Small Water ◽  
Quality Of Water ◽  
Small Water Systems

Small water systems can experience a fluctuating quality of water in the distribution system after disinfection. As chlorine is the most common disinfectant for small systems, the occurrence of disinfection byproducts (DBPs) represents a common problem for these systems. Riverbank filtration (RBF) can be a valuable solution for small communities located on riverbanks. The objectives of this study were to evaluate (i) the improvements in water quality at two selected RBF systems, and (ii) the potential lower concentrations of DBPs, in particular, trihalomethanes (THMs), in small systems that use RBF. Two small communities in Nebraska, Auburn and Nebraska City, using RBF were selected. Results from this study highlight the ability of RBF systems to consistently improve the quality of the source water and reduce the occurrence of THMs in the distribution water. However, the relative removal of THMs was directly impacted by the dissolved organic carbon (DOC) removal. Different THM concentrations and different DOC removals were observed at the two RBF sites due to the different travel distances between the river and the extractions wells.

Hydropower reservoir sediment and water quality assessment

2017 ◽  
Vol 28 (1) ◽  
pp. 43-56 ◽  
Author(s):  
Marcus Vinicius Estigoni ◽  
Renato Billia Miranda ◽  
Frederico Fabio Mauad
Keyword(s):  
Water Quality ◽  
High Rate ◽  
Upstream Region ◽  
Reservoir Sedimentation ◽  
Layer By Layer ◽  
Nutrient Loads ◽  
Content Type ◽  
Positive Effects ◽  
Sedimentation Process ◽  
Sediment Particles

Purpose Finer sediment particles (silt and clay) transported by rivers carry the major part of nutrient loads by absorption; thus, sediment settling can remove nutrients from the water column. The purpose of this paper is to analyze the relation between reservoir sedimentation and water quality by assessing the reservoir sedimentation process and the sediments’ characteristics. Design/methodology/approach Bathymetric surveys from 2004 to 2014 were analyzed to assess the sedimentation process. Core samples provided information on a layer-by-layer basis of the sediment deposits, and water samples near the surface and near the bottom provided information on sediment concentration, and adsorbed and dissolved nutrients. Findings The upstream region of a reservoir is already silted. From 2004 to 2014, the delta evoluted approximately 500 m downstream and the deposits were mainly composed of clay. An area of approximately 1,000 m between the delta and the dam should still be able to continue allowing sediment deposition in the coming years. Most of the nutrients were absorbed into the sediment particles, except for the nitrogen measured in the dry season. Research limitations/implications Although analyses of the full cycle of the nutrients were not carried out, the constant sediment trapping of finer sediments and the high rate of absorbed nutrients in the suspended sediment support the hypothesis that the reservoir has removed nutrients from aqueous media by adsorption into sediments. Practical implications In the studied case, reservoir sedimentation has led to better water quality downstream. Originality/value It is shown in this study that reservoir sedimentation may have positive effects on river water quality.

Evaluation of a MF membrane system composed of pre coagulation-sedimentation and chlorination for water reuse

2006 ◽  
Vol 54 (10) ◽  
pp. 115-121 ◽  
Author(s):  
S.H. Lee ◽  
B.C. Lee ◽  
S.Y. Moon ◽  
Y.S. Choi ◽  
N.Y. Jang ◽  
...  
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
River Water ◽  
Removal Efficiency ◽  
Membrane Filtration ◽  
Transmembrane Pressure ◽  
Stable Operation ◽  
Feed Water ◽  
Promising Alternative ◽  
Sedimentation Process

In this research, we investigated the variation of transmembrane pressure and permeate water quality in pre-coagulation and sedimentation with iron based coagulant, and chlorination of feed water for PVDF (Polyvinylidene fluoride) based MF membrane filtration. NaClO was fed to the membrane module at a dosage of 0.5 mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were employed. In the case of river surface water, the transmembrane pressure increased abruptly in 500 hours operation. On the contrary, no significant increase in transmembrane pressure was observed for coagulated water and coagulated-settled water for 1200 hours operation. The turbidity of permeate was lower than the detection limit for all applied waters. The removal efficiency for humic substances in coagulated water and coagulated-settled water was approximately ten times higher than that in surface river water. And, the removal efficiency for TOC and DOC was approximately two times higher than that in surface river water. From the results of the operation, it can be observed that it is possible to maintain stable operation at 0.9 m3/m2-day filtration flux through a combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when the pre-coagulation-sedimentation process was combined with pre-chlorination. With respect to fouling reduction and operation efficiency increase in membrane filtration, the pre-coagulation/sedimentation process is a promising alternative.

Cold climate facultative lagoons

1984 ◽  
Vol 11 (3) ◽  
pp. 542-555 ◽  
Author(s):  
Timothy Tilsworth ◽  
Daniel W. Smith
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Electrical Power ◽  
Cold Climate ◽  
Design Parameters ◽  
Small Communities ◽  
Water Quality Protection ◽  
Design Engineers ◽  
Skilled Manpower ◽  
Secondary Effluents

Facultative lagoons are of great importance to small communities of Alaska and northern Canada. Severe climatological conditions along with seriously impeded economic development have dramatically reduced the viable alternatives available for wastewater treatment. Design engineers face almost formidable constraints when attempting to produce “secondary” effluents for these communities. Because of permafrost, the absence of electrical power, average annual temperatures as low as −12 °C (10°F), the lack of skilled manpower, and other operating restrictions, lagoons can be of strategic importance to water quality protection in these locations.The use of “southern” technology may not be applicable under arctic–subarctic conditions and even if it is applicable it must be used with considerable reservation. This paper reviews the use of facultative lagoons in cold climate areas and addresses issues of design parameters, economics, and the system's ability to meet wastewater treatment regulations and water quality standards. Consideration of factors influenced by temperature including psychrophilic organisms and ice cover are reviewed in this discussion along with a “common sense” approach to design. Key words: lagoons, cold, permafrost, wastewater, design, BOD, ponds, facultative, algae, northern, ice, anaerobic, kinetics, arctic.

Test Validation Without Measurement

2016 ◽  
Vol 32 (3) ◽  
pp. 204-214 ◽  
Author(s):  
Emilie Lacot ◽  
Mohammad H. Afzali ◽  
Stéphane Vautier
Keyword(s):  
Test Data ◽  
Test Scores ◽  
Scientific Explanation ◽  
Test Validation ◽  
Clinical Tests ◽  
Ethical Perspective ◽  
Power Of Test ◽  
Memory Accuracy ◽  
Social Uses ◽  
Special Case

Abstract. Test validation based on usual statistical analyses is paradoxical, as, from a falsificationist perspective, they do not test that test data are ordinal measurements, and, from the ethical perspective, they do not justify the use of test scores. This paper (i) proposes some basic definitions, where measurement is a special case of scientific explanation; starting from the examples of memory accuracy and suicidality as scored by two widely used clinical tests/questionnaires. Moreover, it shows (ii) how to elicit the logic of the observable test events underlying the test scores, and (iii) how the measurability of the target theoretical quantities – memory accuracy and suicidality – can and should be tested at the respondent scale as opposed to the scale of aggregates of respondents. (iv) Criterion-related validity is revisited to stress that invoking the explanative power of test data should draw attention on counterexamples instead of statistical summarization. (v) Finally, it is argued that the justification of the use of test scores in specific settings should be part of the test validation task, because, as tests specialists, psychologists are responsible for proposing their tests for social uses.

Sign in / Sign up

Export Citation Format

Share Document