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.

Removal of particulates, natural organic matters, and microorganisms in a surface amended slow sand filter

2002 ◽  
Vol 2 (5-6) ◽  
pp. 387-394
Author(s):  
H.-B. Jun ◽  
Y.-J. Lee ◽  
S.-S. Shin
Keyword(s):  
Surface Treatment ◽  
Raw Water ◽  
Sand Filters ◽  
Water Turbidity ◽  
Turbidity Removal ◽  
Sand Filter ◽  
Organic Matters ◽  
Slow Sand Filter ◽  
Natural Organic Matters ◽  
Filter Bed

Removal characteristics of particulates, natural organic matters, and microorganisms with six slow sand filter units were measured with a diameter of 50 mm and packed with sand to a depth of 50, 150, 300, 600, and two 700 mm, respectively. One of the 700 mm depth filters was amended by covering the surface of the filter bed with a prefilter. The raw water turbidity and pH was in the range of 1.5-2.0 NTU, and 7.0-7.7, respectively. Turbidity in each filter effluent was decreased as the depth of filter medium increased. However, a greater part of influent turbidity was removed within the top layer of the slow sand filters. Turbidity removal in the 700 mm depth filter with prefilter was similar to that without the prefilter, however, the removal of particles smaller than 2 mm was improved with the prefilter. The particles greater than 10 mm could be removed within the upper 50 mm depth in the slow sand filter. A greater fraction of the particles smaller than 2 mm was removed within the upper 50 mm, however, they were also removed in the deeper sand bed. The removal efficiency of DBP precursors represented by DOC and UV-254 absorbance was 9.2-31% and 2-31%, respectively. pH drop in the 50 mm depth filter was 0.12, while that in the 700 mm depth filter was 0.19. The effects of surface treatment with prefilter on UVA and DOC were not apparent.

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.

Development of automatic coagulant dosage control technology for rapid change of raw water quality parameters

2012 ◽  
Vol 12 (6) ◽  
pp. 918-925 ◽  
Author(s):  
Y. Sangu ◽  
H. Yokoi ◽  
H. Tadokoro ◽  
T. Tachi
Keyword(s):  
Water Quality ◽  
Pilot Scale ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Control Technology ◽  
Raw Water ◽  
Control Logic ◽  
Water Turbidity ◽  
Coagulant Dosage ◽  
Raw Water Quality

An automatic coagulant dosage control technology for water purification plants was developed to deal with rapid changes of raw water quality parameters. Control logic was developed to decide coagulant dosage based on aluminum concentration in rapid mixing tank water based on results of semi-pilot scale experiments. This logic enabled quick feedback on the excess or lack of coagulant. It was found that the aluminum residual rate, which was proposed as an indicator of coagulation reactions, could be given as a function of coagulant dosage and turbidity. The effectiveness of the control logic was verified in semi-pilot scale experiments. Settled water turbidity was within ±0.5 NTU of target value even when raw water turbidity increased rapidly up to 100 NTU.

scholarly journals Removals of cryptosporidium parvum oocysts and cryptosporidium-sized polystyrene microspheres from swimming pool water by diatomaceous earth filtration and perlite-sand filtration

2017 ◽  
Vol 15 (3) ◽  
pp. 374-384 ◽  
Author(s):  
Ping Lu ◽  
James E. Amburgey ◽  
Vincent R. Hill ◽  
Jennifer L. Murphy ◽  
Chandra L. Schneeberger ◽  
...  
Keyword(s):  
Cryptosporidium Parvum ◽  
Filtration Rate ◽  
Diatomaceous Earth ◽  
Pilot Scale ◽  
Full Scale ◽  
Swimming Pool ◽  
Swimming Pools ◽  
Sand Filtration ◽  
Sand Filter ◽  
Cryptosporidium Parvum Oocysts

Removal of Cryptosporidium-sized microspheres and Cryptosporidium parvum oocysts from swimming pools was investigated using diatomaceous earth (DE) precoat filtration and perlite-sand filtration. In pilot-scale experiments, microsphere removals of up to 2 log were obtained with 0.7 kg·DE/m2 at a filtration rate of 5 m/h. A slightly higher microsphere removal (2.3 log) was obtained for these DE-precoated filters when the filtration rate was 3.6 m/h. Additionally, pilot-scale perlite-sand filters achieved greater than 2 log removal when at least 0.37 kg/m2 of perlite was used compared to 0.1–0.4 log removal without perlite both at a surface loading rate of 37 m/h. Full-scale testing achieved 2.7 log of microspheres and oocysts removal when 0.7 kg·DE/m2 was used at 3.6 m/h. Removals were significantly decreased by a 15-minute interruption of the flow (without any mechanical agitation) to the DE filter in pilot-scale studies, which was not observed in full-scale filters. Microsphere removals were 2.7 log by perlite-sand filtration in a full-scale swimming pool filter operated at 34 m/h with 0.5 kg/m2 of perlite. The results demonstrate that either a DE precoat filter or a perlite-sand filter can improve the efficiency of removal of microspheres and oocysts from swimming pools over a standard sand filter under the conditions studied.

scholarly journals Removal of oxidative stress and genotoxic activities during drinking water production by ozonation and granular activated carbon filtration

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Maria Yu ◽  
Elin Lavonen ◽  
Agneta Oskarsson ◽  
Johan Lundqvist
Keyword(s):  
Oxidative Stress ◽  
Drinking Water ◽  
Activated Carbon ◽  
Drinking Water Treatment ◽  
Pilot Scale ◽  
Full Scale ◽  
Raw Water ◽  
Treatment Efficiency ◽  
Drinking Water Production ◽  
Treatment Technologies

Abstract Background Bioanalytical tools have been shown to be useful in drinking water quality assessments. Here, we applied a panel of in vitro bioassays to assess the treatment efficiency of two pilot-scale treatments: ozonation and granular activated carbon (GAC) filtration at a drinking water treatment plant (DWTP). The pilot-scale systems were studied alongside a full-scale treatment process consisting of biological activated carbon (BAC) filtration, UV disinfection, and monochloramine dosing. Both systems were fed the same raw water treated with coagulation/flocculation/sedimentation and sand filtration. The endpoints studied were oxidative stress (Nrf2 activity), genotoxicity (micronuclei formations), aryl hydrocarbon receptor (AhR) activation, as well as estrogen receptor (ER) and androgen receptor (AR) activity. Results Nrf2, AhR, and ER activities and genotoxic effects were detected in the incoming raw water and variability was observed between the sampling events. Compared to most of the samples taken from the full-scale treatment system, lower Nrf2, AhR, and ER bioactivities as well as genotoxicity were observed in all samples from the pilot-scale systems across all sampling events. The most pronounced treatment effect was a 12-fold reduction in Nrf2 activity and a sixfold decrease in micronuclei formations following ozonation alone. GAC filtration alone resulted in sevenfold and fivefold reductions in Nrf2 activity and genotoxicity, respectively, in the same sampling event. Higher bioactivities were detected in most samples from the full-scale system suggesting a lack of treatment effect. No androgenic nor anti-androgenic activities were observed in any sample across all sampling events. Conclusions Using effect-based methods, we have shown the presence of bioactive chemicals in the raw water used for drinking water production, including oxidative stress, AhR and ER activities as well as genotoxicity. The currently used treatment technologies were unable to fully remove the observed bioactivities. Ozonation and GAC filtration showed a high treatment efficiency and were able to consistently remove the bioactivities observed in the incoming water. This is important knowledge for the optimization of existing drinking water treatment designs and the utilization of alternative treatment technologies.

scholarly journals Turbidity removal by rapid sand filter using anthracite coal as capping media

2021 ◽  
Vol 4 (1) ◽  
pp. 69-73
Author(s):  
Gopal Tamakhu ◽  
Iswar Man Amatya
Keyword(s):  
Comparative Analysis ◽  
Water Treatment ◽  
Bituminous Coal ◽  
Pilot Scale ◽  
Sand Filters ◽  
Turbidity Removal ◽  
Sand Filter ◽  
Filter Materials ◽  
Water Treatment Plants ◽  
Anthracite Coal

Rapid sand filters are very common in all conventional water treatment plants. Capping of existing rapid sand filters can be the promising method of improving the performance of rapid sand filters. Capping is process in which upper sand bed layer of few cm is replaced with capping material. However, this technique is limited in India due to unavailability of filter materials apart from sand. Some materials suitable for capping are anthracite coal, PVC granules, bituminous coal, broken bricks, etc. The attempt is made to study the effect of capping of Rapid sand filters by the use of anthracite coal as a capping media by pilot scale study. A series of test runs and experiments using different influent turbidity were tried. The pilot scale study has shown very encouraging results. Comparative analysis shows that higher rate of filtration is possible along with higher filter run and less backwash requirement. In the present work, conventional rapid sand filter and capped rapid sand filter are compared.

Formation and Removal of Off-Flavour Compounds during Ozonation and Filtration through Biologically Active Sand Filters

1988 ◽  
Vol 20 (8-9) ◽  
pp. 245-253 ◽  
Author(s):  
B. V. Lundgren ◽  
A. Grimvall ◽  
R. Sävenhed
Keyword(s):  
Gas Chromatography ◽  
Flow Rate ◽  
Oxygen Supply ◽  
Water Flow Rate ◽  
Biologically Active ◽  
Raw Water ◽  
Sand Filters ◽  
Sand Filter ◽  
Flavour Compounds ◽  
By Products

Formation and removal of off-flavour compounds during ozonation and during filtration through biologically active sand filters have been evaluated by gas chromatography and column sniffing. A well aerated sand filter (0.5 m deep) with a water flow rate of 25 mm/h was able to produce an almost odourless water from a raw water with a strong muddy and earthy off-flavour. Frequently occurring off-flavour compounds, such as geosmin, 2-methylisobomeol, 2,4,6-trichloroanisole, 1-octen-3-one and dimethyl trisulphide, were all effectively removed, provided the oxygen supply was sufficiently high. The removal of colour, however, was not satisfactory. Treatment with ozone removed the colour of the water and caused a dramatic change in odour quality. Certain off-flavour compounds, such as geosmin and 2-methylisobomeol, decreased in concentration, while several other off-flavour compounds, such as octanal, increased in concentration. The ozonation by-products were only partly removed during sand filtration, and the filter effluent had a weak, but noticeable, off-flavour. Chromatographic sniffing indicated that some of the ozonation by-products were, in fact, less amenable to biodegradation than the off-flavour compounds that were removed by ozonation.

Characterization of Particles in Slow Sand Filtration at North Caribou Water Treatment Plant

2003 ◽  
Vol 38 (1) ◽  
pp. 153-168 ◽  
Author(s):  
Beata Gorczyca ◽  
David London
Keyword(s):  
Water Treatment ◽  
Microscopic Analysis ◽  
Plant Design ◽  
Raw Water ◽  
Filter Media ◽  
Sand Filters ◽  
Sand Filter ◽  
Particle Counter ◽  
Filter Performance ◽  
Slow Sand Filter

Abstract Microscopic analysis of particles in water can indicate the size of filter media required, and can be used to monitor filter performance. This study investigated a malfunctioning slow sand filter in a water treatment facility on a First Nations community in Northern Ontario. There has been a boil-water advisory in the community due to high turbidity in the drinking water since the plant was put into operation. Also, the slow sand filters in the plant clog frequently resulting in outflow volumes significantly below the plant design capacity. On-line particle counts and microscopic analysis of water were conducted in the plant at various points before and after the slow sand filters. Microscopic analysis of the slow sand filter effluent showed that the high water turbidity was due to an increased concentration of particles smaller than 2 µm in size. This observation could not have been made with the particle counter data alone, as it is not capable of measuring particles of that size. Visual inspection of microscopic images of these small particles indicated that they were being washed out from the filter media, and did not originate from the raw water. Significant numbers of large filter-clogging diatoms (up to 50 µm in size) were identified under the microscope; yet, the particle counter did not report particles larger than 15 µm in raw water supply. Turbidimeters and particle counters were found to be unable to identify these diatoms, due to the transparent nature of the cell walls of these microorganisms. It is likely that most of these diatoms originated from sediment accumulated in the raw water intake pipe.

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.

A case study of dissolved air flotation for seasonal high turbidity water in Korea

2004 ◽  
Vol 50 (12) ◽  
pp. 245-253 ◽  
Author(s):  
S.B. Kwon ◽  
H.W. Ahn ◽  
C.J. Ahn ◽  
C.K. Wang
Keyword(s):  
Operation Mode ◽  
Raw Water ◽  
Freshwater Algae ◽  
Water Turbidity ◽  
Dissolved Air Flotation ◽  
Flotation Process ◽  
Direct Filtration ◽  
Air Flotation ◽  
Full Scale Tests ◽  
Dissolved Air

A DAF (Dissolved-Air-Flotation) process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when freshwater algae blooms occur or raw water turbidity becomes high. Pre-sedimentation is operated in case when the raw water turbidity is very high due to rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of the raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than the conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while the removal of them by sedimentation is more difficult. One of the main concerns for DAF operation is a high raw water turbidity. DAF is not adequate for raw water, which is more turbid than 100 NTU. In order to avoid this problem, pre-sedimentation basins are installed in the DAF plant to decrease the turbidity of the DAF inflow. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, it is suggested that pre-sedimentation with optimum coagulation prior to DAF is the appropriate treatment scheme.

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