Pre-Ozonation-Coagulant Interactions in Direct Filtration

2010 ◽  
Vol 45 (3) ◽  
pp. 317-326 ◽  
Author(s):  
Murat Eyvaz ◽  
Hatice Deniz ◽  
Tuğrul S. Aktaş ◽  
Ebubekir Yüksel ◽  
Ahmet M. Saatçi
Keyword(s):  
Ferric Chloride ◽  
Aluminum Sulfate ◽  
Pilot Scale ◽  
The Other ◽  
Design Parameters ◽  
Dimensionless Number ◽  
Raw Water ◽  
Direct Filtration ◽  
Effluent Quality ◽  
Sulfate Application

Abstract Pre-ozonation–coagulant interactions effects in relation to the coagulant type and dosage in direct filtration of surface waters were investigated. The performance of the process was evaluated by monitoring the effluent quality and head loss development through the filter bed. Two identical pilot scale filter columns filtering the same raw water were operated in parallel. The raw water was brought from Ömerli Reservoir in Istanbul. Before filtering, the raw water flow was split into two equal flows. One of the streams was pre-ozonated and the other was aerated using contact chambers with equal volumes equipped with same number and type of diffusers. In coagulation experiments, one of the filters was operated using aluminum sulfate as a coagulant while the other one was run with ferric chloride. For similar filter run times, the effluent quality was always better with pre-ozonation compared to aeration. It was also observed that, aluminum sulfate application gave more favorable results for both particle and turbidity removal compared to ferric chloride. Ives’ filterability index which incorporates the important filtration design parameters such as: effluent quality, the headloss and the velocity of filtration into a dimensionless number was used for the comparison of the experimental results.

Effects of intermittent polyelectrolyte addition on water quality in direct filtration

2011 ◽  
Vol 46 (1) ◽  
pp. 52-63
Author(s):  
Murat Eyvaz ◽  
Tugrul S. Aktas ◽  
Ebubekir Yuksel ◽  
A. Mete Saatci
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Design Parameters ◽  
Dimensionless Number ◽  
Effluent Water ◽  
Sand Filters ◽  
Direct Filtration ◽  
Effluent Quality ◽  
Cationic Polyelectrolytes

The effects of intermittent polyelectrolyte addition on the quality of effluent water and on the development of filter headloss were studied. Anionic and cationic polyelectrolytes were applied to two similarly constructed pilot sand filters. The surface water used in the study was obtained from Ömerli, which is one of the main drinking water reservoirs of Istanbul. Six sets of experiments were carried out. The objective of the experiments in the first three sets was to determine the type and dose of suitable polyelectrolyte. The polyelectrolytes were then added intermittently and continuously in the last three sets. Intermittent addition of polyelectrolyte produced better effluent quality and reduced the polyelectrolyte consumption by half with much less headloss. Ives' Filterability Index, which incorporates the important filtration design parameters such as effluent quality, the headloss and the velocity of filtration into a dimensionless number, was used for the comparison of the experimental results.

Évolution du nombre de particules dans l'eau filtrée d'une filière de filtration directe utilisant le polychlorure d'aluminium

1999 ◽  
Vol 26 (6) ◽  
pp. 771-781
Author(s):  
Souleymane Ndiongue ◽  
Raymond Desjardins ◽  
Michèle Prévost ◽  
Chantal Morissette
Keyword(s):  
The Other ◽  
Raw Water ◽  
Polyaluminum Chloride ◽  
Direct Filtration ◽  
Total Particle ◽  
High Turbidity ◽  
Particle Counts ◽  
St Lawrence River ◽  
Do So

This text presents and discusses the performances of direct filtration evaluated by means of particle counts and turbidity of raw water in periods of low and high turbidity. It also deals with the relationships between the removals of particles measuring from 2 to 150 µm (total counts) and those of particles in the other size ranges, which vary from 2 to 5 and from 5 to 15 µm. The tests were carried out on a pilot plant (20 m3/h) that treats waters from the St. Lawrence River (Canada) using the polyaluminum chloride (PACl) coagulation method followed by rapid filtration at 10 m/h. The results show that when the turbidity of the raw water is low, it is not always possible to predict a filter breakthrough based on the turbidity of its effluent, whereas it is possible to do so by observing the evolution of the particle counts. There exist good correlations between the removals of the total particle counts (2-150 µm) and those of the counts of particles in the other size ranges (2-5 and 5-15 µm). Furthermore, the evolution of all these ranges of particle size reveals the same tendencies with respect to the quality of the filtered water.Key words: direct filtration, in-line filtration, filtration, particle counts, turbidity, polyaluminum chloride.

scholarly journals Cryptosporidium Oocysts Removal by Upflow Direct Filtration: Pilot Scale Assessment

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1328
Author(s):  
Marcely Ferreira Nascimento ◽  
Yovanka Pérez Ginoris ◽  
Cristina Celia Silveira Brandão
Keyword(s):  
Fine Sand ◽  
Pilot Scale ◽  
Stable Operation ◽  
Raw Water ◽  
Direct Filtration ◽  
Water Flows ◽  
Cryptosporidium Oocysts ◽  
Residual Values ◽  
Water Values ◽  
Coarse To Fine

Studies on the removal of Cryptosporidium oocysts by direct filtration suggested that high removal efficiencies (>3.0 log) can be achieved, but the vast majority of the studies focused on the assessment of downflow direct filtration. However, in comparison with downflow direct filtration, filters in upflow direct filtration systems use lower filtration rates, deeper stratified bed, and water flows from coarse to fine sand grain, which may improve the removal of oocysts. In this context, we evaluated the removal of Cryptosporidium oocysts using upflow direct filtration, on a pilot scale, to treat Paranoá Lake water (Brazil) seeded with Cryptosporidium oocysts. The experiments were conducted with raw water with low turbidity (3.2–5.7 NTU) and induced higher turbidity (28–30 NTU). Non-parametric statistical analysis was used to verify correlations between the filtered water values and removal of oocysts, particles, and turbidity. In general, no correlation was observed between the parameters analyzed, nor between their removals. The exception was the correlation between residual values of Cryptosporidium oocysts and particles of 2 to 7 µm during ripening, an aspect that needs further evaluation. Under stable operation, average removal of Cryptosporidium oocysts by upflow direct filtration was >3.87 log. During ripening, removal of oocysts was around 1 log lower.

Effect of Pre-Ozonation on Organics Removal by In-Line Direct Filtration

1993 ◽  
Vol 27 (11) ◽  
pp. 81-90 ◽  
Author(s):  
J. E. Tobiason ◽  
J. K. Edzwald ◽  
D. A. Reckhow ◽  
M. S. Switzenbaum
Keyword(s):  
Performance Measures ◽  
Pilot Scale ◽  
Full Scale ◽  
Continuous Operation ◽  
Raw Water ◽  
Sand Filters ◽  
Water Turbidity ◽  
Sand Filter ◽  
Direct Filtration ◽  
Organics Removal

A pilot-scale study of the effects of pre-ozonation on the performance of in-line direct filtration was carried out. Performance measures included filtered water turbidity, unit filter run volumes, and organics in filtered waters: DOC, UV254, AOC and DBPs. Continuous operation of four dual media GAC/sand filters with and without pre-ozonation and chlorinated backwash and a dual media anthracite/sand filter were compared to full-scale performance. Pre-ozonation frequently results in longer filter runs, causes a twofold increase in raw water AOC and has little effect on raw water DOC. GAC/sand filters consistently reduced the AOC in the ozone train to levels below that of the full-scale plant and also provided 25 % lower DOC levels as compared to anthracite/sand filters. The effect of ozone and filtration on chlorinated DBPs followed overall DOC removal while DBPs created by ozonation followed AOC removal trends.

Effect Factors of Air Flotation Treating Micropolluted Source Water in South China

2011 ◽  
Vol 99-100 ◽  
pp. 1063-1066
Author(s):  
Gui Qing Gao
Keyword(s):  
Ferric Chloride ◽  
South China ◽  
Aluminum Chloride ◽  
Feed Rate ◽  
Gas Pressure ◽  
Source Water ◽  
Raw Water ◽  
Effect Factors ◽  
Effluent Quality ◽  
Aluminum Sulphate

The Southern source water carries such characteristics as high algae, low turbidity and micro-polluted. In order to make flotation better applied to the source water, the following factors are researched to find out the influence on the flotation from type and dosage of coagulant, dissol- ved air pressure, air inflow. Aluminum sulphate, ferric chloride, poly aluminum chloride (PAC) are selected. With less PAC, scum generated less, the coagulant dose is 1.25mg/L.Dissolved gas pressure is directly related to bubble size.When the pressure is greater than 0.42Mpa,the effluent quality deteriorates as the pressure increases.The volume of inflow gas into the raw water is related to turbidity and capacity.The higher the turbidity of the water is, the greater the capacity will be, so the higher feed rate can be chosen.

Enteric viruses in drinking water supplies

2002 ◽  
Vol 2 (3) ◽  
pp. 17-22
Author(s):  
A.P. Wyn-Jones ◽  
J. Watkins ◽  
C. Francis ◽  
M. Laverick ◽  
J. Sellwood
Keyword(s):  
Drinking Water ◽  
Heavy Rainfall ◽  
Liquid Culture ◽  
Plaque Assay ◽  
Enteric Viruses ◽  
Enteric Virus ◽  
The Other ◽  
Raw Water ◽  
Rt Pcr ◽  
Water Supplies

Two rural spring drinking water supplies were studied for their enteric virus levels. In one, serving about 30 dwellings, the water was chlorinated before distribution; in the other, which served a dairy and six dwellings the water was not treated. Samples of treated (40 l) and untreated (20 l) water were taken under normal and heavy rainfall conditions over a six weeks period and concentrated by adsorption/elution and organic flocculation. Infectious enterovirus in concentrates was detected in liquid culture and enumerated by plaque assay, both in BGM cells, and concentrates were also analysed by RT-PCR. Viruses were found in both raw water supplies. Rural supplies need to be analysed for viruses as well as bacterial and protozoan pathogens if the full microbial hazard is to be determined.

scholarly journals The Influence of Design Parameters on Straight Bevel Gear Dynamics

2015 ◽  
Vol 5 (2) ◽  
pp. 114
Author(s):  
Chiu-Fan Hsieh ◽  
You-Qing Zhu
Keyword(s):  
Statistical Analysis ◽  
The Other ◽  
Design Parameters ◽  
Bevel Gears ◽  
Straight Bevel Gear ◽  
Pressure Angle ◽  
Stress Fluctuation ◽  
Shaft Angle ◽  
Statistical Results ◽  
Component Force

<p class="1Body">This study analyzes the influence of design parameters on the dynamics of straight bevel gears by constructing a model that allows variation in the shaft angle, pressure angle, and backlash. According to the statistical analysis, the order of influence of these parameters on weight is shaft angle &gt; pressure angle &gt; backlash. When the shaft angle is 90°, the statistical results show the drive is stable and the stress fluctuation level is low. The pressure angle, on the other hand, can affect the gear’s dynamic property by influencing the driving component force on the gear and the component force on the shaft. The results for the shaft and pressure angles are used to determine the appropriate backlash. Overall, the analysis not only provides designers with an important reference but explains the dominance in the market of gear designs with a 90° shaft angle and a 20° pressure angle.</p>

Observations of blanket characteristics in full-scale floc blanket clarifiers

2003 ◽  
Vol 47 (1) ◽  
pp. 197-204 ◽  
Author(s):  
L.C. Chen ◽  
S.S. Sung ◽  
W.W. Lin ◽  
D.J. Lee ◽  
C. Huang ◽  
...  
Keyword(s):  
Treatment Process ◽  
Combined Treatment ◽  
The Other ◽  
Raw Water ◽  
Water Turbidity ◽  
Capillary Suction ◽  
Zeta Potentials ◽  
High Turbidity ◽  
Water Supply Company ◽  
Clarified Water

We monitored the changes in concentrations, zeta potentials, sizes and capillary suction times of the solids flocs in the clarified water from eight floc blanket clarifiers of PingTsan Water Works of Taiwan Water Supply Company with low (&lt;10 NTU) and high (&gt;100 NTU) turbidity raw water. For the former, one-stage coagulation-sedimentation treatment was adopted which yielded a rather unstable blanket. Complete washout was noticeable when the PACl dosage was insufficient. On the treatment of high-turbidity raw water, on the other hand, the Works adopted the combined treatment process, that is, the raw water was first coagulated and settled in a pre-sedimentation tank, afterwards, its effluent was coagulated again and clarified in the clarifiers. The resulting flocs could form a networked blanket that was relatively stable to the shock load in raw water turbidity.

Performance and microbial dynamics in the coarse pore filtration activated sludge process at different SRTs (solids retention times)

2003 ◽  
Vol 47 (12) ◽  
pp. 73-80 ◽  
Author(s):  
M.R. Alavi Moghaddam ◽  
Y. Guan ◽  
H. Satoh ◽  
T. Mino
Keyword(s):  
Microbial Population ◽  
The Other ◽  
Activated Sludge Process ◽  
Filamentous Bacteria ◽  
Microbial Dynamics ◽  
Effluent Quality ◽  
Solids Retention ◽  
Microbial Population Dynamics ◽  
Operation Pressure ◽  
Filter Clogging

In this research, three SRTs (about 10, 30 and 75 days (without wasting the sludge except for sampling)) were applied to three reactors equipped with non-woven and coarse pore filter modules. The flux was adjusted to about 1 m/d during operation. The main objective of the study was to compare the performance and microbial population dynamics under different SRTs in this process. The results of reactors with SRTs of about 10 and 30 days have shown very good effluent quality without any clogging problem for more than 4 months of operation. For the reactor with long SRT (75 days), the filter clogging was observed after about 80 days of operation and caused an increase in the operation pressure and deterioration in effluent quality on some days. Excessive abundance of filamentous bacteria was observed in the reactor with SRT of about 10 days, which had the best effluent quality. According to the FISH results, type 021N was predominant in the reactor with long SRT, which had the clogging problem. On the other hand, other reactors (with SRTs of about 10 and 30 days) did not contain much type 021N, but some other filamentous bacteria dominated. Maximum EPS concentration (as mg/L) was observed in the reactor with long SRT. Also the abundance of two types of metazoa (Pristina sp. and tardigrades) was observed in the reactor with long SRT, which had the clogging problem and poor effluent quality.

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