Effect of ozone injection location on filter performance in direct filtration

2002 ◽  
Vol 46 (9) ◽  
pp. 171-177 ◽  
Author(s):  
E. Yüksel ◽  
Ö Akgiray ◽  
A.M. Saatçi ◽  
H.Z. Sarikaya ◽  
I. Koyuncu
Keyword(s):  
Pilot Scale ◽  
Head Loss ◽  
Sand Filters ◽  
Injection Point ◽  
Particle Count ◽  
Direct Filtration ◽  
Filter Performance ◽  
Detention Tank ◽  
Filter Bed ◽  
Ozone Injection

Two identical pilot scale sand filters were operated in parallel to study the effects of preozonation in direct filtration. No coagulants were used. The influent of one filter was ozonated, whereas the influent to the second filter was aerated. Significantly improved reduction in turbidity, particle count, and iron was observed with the filter receiving preozonated water. The head loss development rate was increased as a result of using ozone. In a second set of experiments, the effects of ozone injection point on filter performance were investigated. Two identical filters both receiving preozonated water were operated. With one of the filters, the raw water was ozonated immediately before it entered the filter. The entrance of the preozonated water to the other filter was delayed by using a detention tank between the ozone contact chamber and the filter. In addition to effluent turbidity and particle count values, zeta potentials of the waters entering the two filters were measured. Head loss development at several locations within each filter bed was also observed and recorded. Slightly better effluent quality (turbidity and particle count) was observed with the filter receiving preozonated water without delay. It was observed that the zeta potential of the prezonated water became more negative with increasing delay time.

scholarly journals Improving Filtrate Quality Using Agrobased Materials as Coagulant Aid

2002 ◽  
Vol 37 (4) ◽  
pp. 745-756 ◽  
Author(s):  
Pramod Kumar Raghuwanshi ◽  
Monika Mandloi ◽  
Arvind J. Sharma ◽  
Hanumat S. Malviya ◽  
Sanjeev Chaudhari
Keyword(s):  
Water Quality ◽  
Water Treatment ◽  
Granular Media ◽  
Moringa Oleifera ◽  
Head Loss ◽  
Turbid Water ◽  
Filter Performance ◽  
Treatment Train ◽  
Strychnos Potatorum ◽  
Filter Bed

Abstract In the present study, an evaluation of agrobased materials (ABM) as a coagulant aid in conjunction with alum has been conducted to determine their efficacy in water treatment. The agrobased materials evaluated are Surjana seed (Moringa oleifera), Nirmali seed (Strychnos potatorum) and maize (Zeemays). Experiments have been conducted simulating a conventional water treatment train consisting of coagulation-flocculation-settling and granular media filtration. Emphasis has been given to the filtration aspect of the treatment train using synthetic turbid water. The filter performance was defined by water quality and head loss development across the filter bed. When Nirmali seed or maize was used as a coagulant aid, the alum dose required was 25 and 15 mg/L, respectively, and the filtrate turbidity achieved was less than 0.2 NTU, whereas alum alone with a dose of 45 mg/L achieved filtrate turbidity levels higher than 1 NTU. Thus, the use of ABM improved the filtrate quality. Head loss in filter with Surjana seed and Maize as coagulant aids was comparable to that of alum alone, whereas it was higher when Nirmali seed was used as a coagulant aid.

Particles Capturing and Correlation with Head Loss in a Pilot-Scale Biological Aerated Filter

2013 ◽  
Vol 409-410 ◽  
pp. 279-286
Author(s):  
Ting Li ◽  
Wen Yi Dong ◽  
Hong Jie Wang ◽  
Jin Nan Lin ◽  
Feng Ouyang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Pilot Scale ◽  
Head Loss ◽  
Biological Aerated Filter ◽  
Air Flow Rate ◽  
Air Velocity ◽  
Lower Velocity ◽  
Aerated Filter ◽  
Filter Bed

Experimental observations of particle capturing through the biological aerated filter bed indicated that air flow rate plays an important role in head loss development by influencing the suspended solids distribution along the depth of the bed as well as the morphology of the deposits. The active height for the SS removal prolonged with the increasing of the air velocity based on the mechanism of first-order kinetics. With the increasing of the superficial air velocity, the effluent SS concentration and the time need to reach the stead-states after backwash both increased. The value of the SS spike in the effluent after backwash at superficial air velocity of 27 m/hr was nearly twice as much as that of 5.4m/hr. Distribution of the deposits at higher air velocity was more uniform. Deposits at lower velocity with air flow rate produced higher head loss gradient. The headloss increased with the increasing of deposits and the increase rate was faster when the deposits exceeded higher value.

scholarly journals Comparison of crushed rock sand and natural river sand as filter media for rapid filtration

2020 ◽  
Author(s):  
Bruno Moreno Ramos da Silva ◽  
Rafael Kopschitz Xavier Bastos ◽  
Pedro Kopschitz Xavier Bastos
Keyword(s):  
Water Treatment ◽  
Pilot Scale ◽  
Head Loss ◽  
Crushed Rock ◽  
Filter Media ◽  
Particle Size Range ◽  
River Sand ◽  
Run Length ◽  
Acid Solubility ◽  
Filter Bed

Abstract The objective of this work was to evaluate the crushed rock sand (CRS) as a filter bed in rapid filtration for water treatment. The experiments were carried out using pilot-scale filtration units: one with a CRS filter bed and the other with natural river sand (NRS). Both filter media were prepared in accordance with typical standards for rapid sand filtration (particle size range and distribution, and filter bed depth), and were further characterized in terms of chemical composition, particles and bulk density, porosity, acid solubility and sphericity coefficient. Over four months, 14 filter runs using filtration rates of 90, 180, 270 and 360 m3 m−2 d−1 were monitored and characterized in terms of run length, head loss increase along filter bed depth, turbidity removal along filter bed depth. Overall, the performance of the CRS filter was similar to or even better than that of the NRS filter, producing filtered water with turbidity lower than 0.50 NTU along the entire run, with head loss increasing rates and run length similar to those of the NRS filter. It is concluded that CRS presents a high potential for use as filter media for rapid filtration in water treatment, without technical or operational disadvantages.

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.

Pilot plant study of alternative filter media for rapid gravity filtration

2012 ◽  
Vol 66 (12) ◽  
pp. 2779-2784 ◽  
Author(s):  
P. D. Davies ◽  
A. D. Wheatley
Keyword(s):  
Particle Size ◽  
Pilot Plant ◽  
Low Cost ◽  
Pilot Scale ◽  
Head Loss ◽  
Filter Media ◽  
Sand Filters ◽  
Extensive Experience ◽  
Recycled Glass ◽  
Pilot Plant Study

Sand has been the main filter media used in rapid gravity filtration since its introduction. The dominance of sand has been due to its low cost and availability. Extensive experience has led to sand filters with a dependable and predictable performance. Sand remains the preferred filter medium but usually with a larger sized anthracite capping to reduce the onset of head loss. Other approved filter media are now commercially available and this paper compares sand with recycled glass, Filtralite® and slate at pilot scale. The results have reaffirmed the basic importance of particle size on head loss and turbidity performance rather than surface activity or specific surface area. The results did suggest, however, that particle shape and packing exerted a stronger influence on performance than previously acknowledged. These could be used to improve the design and the contribution to sustainability made by rapid gravity filters.

Prospective environmental and economic assessment for biotreatment of micropollutants in drinking water resources in Denmark

2015 ◽  
Vol 15 (6) ◽  
pp. 1405-1413 ◽  
Author(s):  
Ivan Muñoz ◽  
Erik de Vries ◽  
Janneke Wittebol ◽  
Jens Aamand
Keyword(s):  
Drinking Water ◽  
Water Resources ◽  
Economic Assessment ◽  
Pilot Scale ◽  
Impact Categories ◽  
Financial Cost ◽  
Sand Filters ◽  
Immobilized Bacteria ◽  
Drinking Water Resources ◽  
Scale Data

A prospective environmental life cycle assessment (LCA) and financial cost assessment is performed to the application of bioaugmentation to sand filters in Danish waterworks, to remove 2,6-dichlorobenzamide (BAM) from drinking water resources. Based on pilot-scale and laboratory-scale data, we compare bioaugmentation to current alternative strategies, namely granular activated carbon (GAC) adsorption, and well re-location. Both assessments identified well re-location as the least preferred option, however, this result is very sensitive to the distance from the waterworks to the new well. When bioaugmentation is compared to GAC, the former has a lower impact in 13 impact categories, but if immobilized bacteria are used, the impacts are higher than for GAC in all impact categories. On the other hand, from a cost perspective bioaugmentation appears to be preferable to GAC only if immobilized bacteria are used.

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.

Elimination of viruses, bacteria and protozoan oocysts by slow sand filtration

2004 ◽  
Vol 50 (1) ◽  
pp. 147-154 ◽  
Author(s):  
W.A.M. Hijnen ◽  
J.F. Schijven ◽  
P. Bonné ◽  
A. Visser ◽  
G.J. Medema
Keyword(s):  
Pilot Plant ◽  
Pathogenic Bacteria ◽  
Laboratory Experiments ◽  
Full Scale ◽  
Sand Filters ◽  
E Coli ◽  
Thermotolerant Coliforms ◽  
Filter Bed ◽  
Scale Data ◽  
Bacteria Removal

The decimal elimination capacity (DEC) of slow sand filters (SSF) for viruses, bacteria and oocysts of Cryptosporidium has been assessed from full-scale data and pilot plant and laboratory experiments. DEC for viruses calculated from experimental data with MS2-bacteriophages in the pilot plant filters was 1.5-2 log10. E. coli and thermotolerant coliforms (Coli44) were removed at full-scale and in the pilot plant with 2-3 log10. At full-scale, Campylobacter bacteria removal was 1 log10 more than removal of Coli44, which indicated that Coli44 was a conservative surrogate for these pathogenic bacteria. Laboratory experiments with sand columns showed 2-3 and >5-6 log10 removal of spiked spores of sulphite-reducing clostridia (SSRC; C. perfringens) and oocysts of Cryptosporidium respectively. Consequently, SSRC was not a good surrogate to quantify oocyst removal by SSF. Removal of indigenous SSRC by full-scale filters was less efficient than observed in the laboratory columns, probably due to continuous loading of these filter beds with spores, accumulation and retarded transport. It remains to be investigated if this also applies to oocyst removal by SSF. The results additionally showed that the schmutzdecke and accumulation of (in)organic charged compounds in the sand increased the elimination of microorganisms. Removal of the schmutzdecke reduced DEC for bacteria by ±2 log10, but did not affect removal of phages. This clearly indicated that, besides biological activity, both straining and adsorption were important removal mechanisms in the filter bed for microorganisms larger than viruses.

scholarly journals Influence of Particle and Grain Size on Sand Filtration: Effect on Head Loss and Turbidity

2020 ◽  
Vol 8 (2) ◽  
pp. 36
Author(s):  
Racha Medjda Bouchenak Khelladi ◽  
Abdelghani Chiboub Fellah ◽  
Maxime Pontié ◽  
Fatima Zohra Guellil
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Granular Media ◽  
Particle Concentration ◽  
Head Loss ◽  
Sand Filtration ◽  
Circular Column ◽  
Filter Performance ◽  
Filter Operation ◽  
Suspended Matters

Sand filtration is an eco-friendly method to treat either drinking water or wastewater ; it requires only natural granular media. It is also easy to use and to maintain ; the only problem they face is clogging that affects filter performance, that can be detected when head loss or turbidity increase. The purpose of this work is to see what are the factors that influence the performance of filter operation, for this, we used a pilot consisting on a circular column filled with sand (from South Algeria), where various parameters were tested; pressure, flow rate, sand granulometry, suspended matters and particle concentration of the water which is filtered. After eighteen weeks of operation, we have found that head loss increases by decreasing granulometry and increasing flow rate, pressure, particle size, and concentration. However, turbidity increases by decreasing particle size and increasing granulometry and particle concentration. Turbidity and head loss have different behaviour towards the same parameter; that is why it is necessary to take them into account in order to find a compromise between acceptable head loss / turbidity for a good functioning of the filter.

Coagulation-Direct Filtration of Soft, Low Alkalinity Humic Waters

1999 ◽  
Vol 40 (9) ◽  
pp. 55-62 ◽  
Author(s):  
Bjørnar Eikebrokk
Keyword(s):  
Natural Organic Matter ◽  
Pilot Scale ◽  
Quality Parameters ◽  
Efficient Removal ◽  
Direct Filtration ◽  
Ph Values ◽  
Optimum Ph ◽  
Calcium Sources ◽  
Ph Conditions ◽  
Removal Efficiencies

Optimisation of coagulation-direct filtration processes with respect to efficient removal of humic substances, i.e. natural organic matter (NOM) has gained a lot of focus in many countries over the last years. This paper presents experimental results from pilot scale research studies aimed at optimising the coagulation-direct filtration process applied to soft and humic raw waters with low turbidity and alkalinity levels. Comprehensive tests of 3 types of raw waters with different NOM content, 5 types of coagulants, and 3 calcium sources for the purpose of corrosion control have been conducted. Removal efficiencies with respect to relevant water quality parameters are presented, with typical relationships between raw water NOM content, coagulant dose requirements and pH. Generally, when applying metal-based coagulants, residual metal concentration was the critical parameter regarding minimum coagulant dose requirements. Typical NOM removal efficiencies were in the range of 75-90% and 40-70% with respect to colour and organic carbon, respectively. Optimum pH conditions for the removal of NOM and/or residual metals do not always coincide with that of turbidity. The experiments also showed that poly-aluminium and ferric chlorides might have some benefits over alum in terms of dose requirements and range of optimum pH values, and that chitosan may be used for colour removal with good results.

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