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.

scholarly journals EFEKTIFITAS PENAMBAHAN MEDIA GEOTEKSTIL PADA SARINGAN PASIR LAMBAT TERHADAP PENYISIHAN PARAMETER KEKERUHAN, JUMLAH COLI DAN COD

2019 ◽  
Vol 8 (2) ◽  
pp. 114
Author(s):  
Yustika Kusumawardani ◽  
Widi Astuti
Keyword(s):  
Continuous Flow ◽  
Flow System ◽  
Surface Structures ◽  
Raw Water ◽  
Sand Filters ◽  
Turbidity Removal ◽  
Sand Filter ◽  
Slow Sand Filter ◽  
The Media ◽  
Number Of Bacteria

Slow sand filter processing is done by separating raw contaminant water which is passed slowly on sand. Fluctuating raw water quality resulted in the schmutzdecke layer not growing optimally. Therefore, it is needed media that help the performance of the sand filter. One of the media used is geotextile. The geotextile is useful as a medium to optimize the growth of microorganisms in the schmutzdecke layer. Geotextiles have similar surface structures such as sand filters as well as their pores. The purpose of this study was to determine the effectiveness of adding geotextiles in reducing turbidity parameters, number of coli and COD. This study used slow sand filter reactor with a continuous flow system of 0.3 m3 / m2.jam for 7 days. Based on the research, the addition of geotextile media is quite effective and can improve the performance of slow sand filter. Percentage of turbidity removal reached 94.27%, coli 99.40% and COD 92.85%. COD values tend to be dynamic as raw water conditions. Geotextiles is quite helpful in growing a layer of schmutzdecke because the structure resembles sand so as to increase the number of bacteria bed filters.

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.

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.

scholarly journals Verification of filter efficiency of horizontal roughing filter by Weglin's design criteria and Artificial Neural Network

2009 ◽  
Vol 2 (1) ◽  
pp. 21-27 ◽  
Author(s):  
◽  
◽  
◽  
◽  
Keyword(s):  
Genetic Model ◽  
Neural Model ◽  
Model Verification ◽  
Design Criteria ◽  
Experimental Setup ◽  
Mean Square ◽  
Raw Water ◽  
Neural Models ◽  
Sand Filter ◽  
Slow Sand Filter

Abstract. The general objective of this study is to estimate the performance of the Horizontal Roughing Filter (HRF) by using Weglin's design criteria based on 1/3–2/3 filter theory. The main objective of the present study is to validate HRF developed in the laboratory with Slow Sand Filter (SSF) as a pretreatment unit with the help of Weglin's design criteria for HRF with respect to raw water condition and neuro-genetic model developed based on the filter dataset. The results achieved from the three different models were compared to find whether the performance of the experimental HRF with SSF output conforms to the other two models which will verify the validity of the former. According to the results, the experimental setup was coherent with the neural model but incoherent with the results from Weglin's formula as lowest mean square error was observed in case of the neuro-genetic model while comparing with the values found from the experimental SSF-HRF unit. As neural models are known to learn a problem with utmost efficiency, the model verification result was taken as positive.

scholarly journals A23 Seasonal abundance of chironomid larvae in slow sand filter bed

2002 ◽  
Vol 53 (Supplement) ◽  
pp. 41
Author(s):  
K. Hirabayashi ◽  
N. Nakamoto ◽  
S. Tanizaki
Keyword(s):  
Seasonal Abundance ◽  
Sand Filter ◽  
Chironomid Larvae ◽  
Slow Sand Filter ◽  
Filter Bed

Slow sand filtration pre-treatment with alum is efficient, but is it effective?

2013 ◽  
Vol 3 (2) ◽  
pp. 106-111 ◽  
Author(s):  
C. C. Dorea
Keyword(s):  
Process Control ◽  
High Efficiency ◽  
Sand Filters ◽  
Sand Filter ◽  
Limited Effectiveness ◽  
Scale Field ◽  
Slow Sand Filter ◽  
High Turbidity ◽  
Pre Treatment ◽  
Run Lengths

Enhancing the performance of slow sand filter pre-treatment with alum (i.e. direct or contact filtration) has been proposed as an alternative to overcome limitations of conventional gravel (roughing) pre-filtration. Experimental results revealed high turbidity reduction efficiencies in alum-dosed pre-filtration. However, due to the alum coagulation, the nature of the particulates in the pre-treatment effluent changed and had a potential to shorten the downstream slow sand filter run lengths by approximately 50% under the conditions tested. Hence, depending on the effluent turbidity levels the effectiveness of the alum-dosed pre-treatment could be compromised, despite its high efficiency. Relatively low turbidity levels (<2 NTU) were needed to minimise excessive headloss development in alum-dosed filters. However, the necessary resources to achieve such process control may not be available in developing country contexts. Furthermore, full-scale field experiences indicated the limited effectiveness of alum dosing prior to slow sand filters and the difficulties in maintaining an adequate chemical dosing in under-resourced settings.

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.

The Effect of Variation in Cone Position Heigth on Raw Water Turbidity Removal in Sedimentation Unit Continuous Discharge Flow (CDF) Method as a New Method

2021 ◽  
Vol 20 (1) ◽  
pp. 58-64
Author(s):  
Ridwan Ridwan ◽  
Reri Afrianita ◽  
Yar Gustina
Keyword(s):  
Removal Efficiency ◽  
Rank Correlation ◽  
New Method ◽  
Raw Water ◽  
Water Turbidity ◽  
Turbidity Removal ◽  
Spearman’S Rank Correlation ◽  
Optimum Position ◽  
Exhaust Stream ◽  
Laboratory Scale Reactor

Unit sedimentasi metode continuous discharges flow (CDF) adalah metode baru dalam menyisihkan kekeruhan yang menggunakan prinsip tangki bocor secara kontinu dan terkendali. Perubahan ketinggian posisi cone dari dasar zona pengendapan ke bagian atas, dapat memperkecil jarak antara sumber aliran buang akibat bocor yang berasal dari cone sebagai sumber gaya baru yang bekerja terhadap flok, dan pada akhirnya meningkatkan efisiensi penyisihan kekeruhan. Penelitian ini bertujuan untuk menganalisis efisiensi penyisihan kekeruhan air baku pada 3 variasi ketinggian posisi cone di zona pengendapan. Penelitian menggunakan reaktor skala laboratorium kapasitas 240 L/jam yang terdiri dari unit koagulasi terjunan, flokulasi baffle channel dan sedimentasi metode CDF. Unit sedimentasi metode CDF yang digunakan adalah CDF 6% dengan variasi ketinggian posisi cone 0 m, 0,33 m dan 0,66 m dari dasar zona pengendapan. Air baku yang digunakan adalah Sungai Batang Kuranji Kota Padang dengan kekeruhan 25,876 – 26,012 NTU dan tawas sebagai koagulan dalam proses koagulasi. Hasil penelitian menunjukkan efisiensi penyisihan kekeruhan pada ketinggian posisi cone 0 m, 0,33 m dan 0,66 m secara berurutan adalah sebesar 82,88%, 83,86% dan 84,60%. Ketinggian posisi cone 0,66 m dari dasar zona pengendapan adalah posisi optimum dengan efisiensi penyisihan kekeruhan 1,72% lebih besar dari posisi cone di dasar zona pengendapan, yaitu 0 m. Analisis pengaruh ketinggian posisi cone terhadap penyisihan kekeruhan menggunakan korelasi Rank Spearman, menunjukkan pengaruh yang sangat kuat, semakin tinggi posisi cone semakin besar efisiensi penyisihan. Bilangan Reynolds (NRe)dan bilangan Froude (NFr) pada aliran buang ini secara berurutan adalah 23,83 dan 9,33x10-4. ABSTRACTThe continuous discharges flow (CDF) sedimentation unit is a new method for removing turbidity using the principle of a continuous and controlled leaking tank. Changes in the height of the cone position from the bottom of the settling zone to the top, can reduce the distance between the exhaust flow sources due to leakage from the cone as a new force source acting on the floc, and ultimately increase the efficiency of turbidity removal. This study aims to analyze the efficiency of raw water turbidity removal at 3 variations in the height of the cone position in the settling zone. The study used a laboratory-scale reactor with a capacity of 240 L/hour consisting of a plunge coagulation unit, baffle channel flocculation, and CDF sedimentation method. The sedimentation unit for the CDF method used is 6% CDF with variations in the height of the cone position 0 m, 0.33 m, and 0.66 m from the bottom of the settling zone. The raw water used is Sungai Batang Kuranji, Padang City with a turbidity of 25.875 – 26.012 NTU and alum as a coagulant in the coagulation process. The results showed that the efficiency of removal of turbidity at the height of the cone 0 m, 0.33 m, and 0.66 m respectively was 82.88%, 83.86%, and 84.60%. The height of the cone position 0.66 m from the bottom of the settling zone is the optimum position with a turbidity removal efficiency of 1.72% greater than the cone position at the bottom of the settling zone, which is 0 m. Analysis of the effect of the height of the cone position on the removal of turbidity using Spearman's Rank correlation showed a very strong influence, the higher the cone position the greater the removal efficiency. Reynolds number (NRe) and Froude number (NFr) in this exhaust stream are 23.83 and 9.33x10-4, respectively.

Use of bauxite for enhanced removal of bacteria in slow sand filters

2016 ◽  
Vol 17 (4) ◽  
pp. 1007-1015 ◽  
Author(s):  
Daniel Urfer
Keyword(s):  
Drinking Water ◽  
Drinking Water Treatment ◽  
Particle Removal ◽  
Sand Filters ◽  
Filter Surface ◽  
Second Stage ◽  
Slow Sand Filter ◽  
Different Depths ◽  
Filter Bed ◽  
Pilot Tests

Slow sand filtration (SSF) is a well-known process for drinking water treatment and is widely used for the production of biologically stable drinking water and particle removal. The removal process of particles and microorganisms is highly dependent on the buildup of the schmutzdecke at the filter surface. During the ripening period and especially for cold waters, the buildup of the schmutzdecke may take several months until such filters are biologically mature and at steady-state regarding their removal performance for particles and microorganisms. In order to improve the performance of SSF in terms of the removal of bacteria, e.g. Escherichia coli and Enterococcus, pilot tests using natural bauxite as a filter media have been performed. The results showed a significant improvement in bacteria retention within the filter bed of a second-stage slow sand filter containing different depths of bauxite.

scholarly journals Effectiveness of combined upflow roughing filter and upflow slow sand filter to reduce turbidity in Citarum water as a source of drinking water

2021 ◽  
Author(s):  
Gede H Cahyana
Keyword(s):  
Drinking Water ◽  
Water Source ◽  
Drinking Water Source ◽  
Surface Loading ◽  
Turbidity Removal ◽  
Sand Filter ◽  
Water Company ◽  
Slow Sand Filter

Turbidity of Citarum River was high, fluctuating and used as drinking water source by people and PDAM (Regional Drinking Water Company). The aim of this study was to determine the ability of upflow roughing filter (URF) and upflow slow sand filter (USSF) in reducing turbidity. It was called multistage filtration (MSF). MSF was varied with and without settler. Gravel diameters and perviousness as follows: 0.5 cm was 0.243, 1 cm: 0.264, 2 cm: 0.265, 5 cm: 0.302 or just 24 - 30% of total URF’s volume. When settler was run with surface loading 0.5 m3/m2/hour, flowrate 0.67 l/minute, turbidity 321.16 - 3,496.53 NTU, efficiency was 57.9 - 96.2%. Settler reduced turbidity significantly. URF1 enhanced turbidity removal. However, URF2, URF3, USSF were not effective. In experiment without settler, turbidity was 130.78 - 533.00 NTU but its reduction in URF1 was bad. But in URF2 turbidity was almost the same as in experiment with settler. Efficiency was 41.9 - 89.1%. Here URF1 and URF2’s function were almost the same as settler and URF1. URF3 was ineffective, can be removed. USSF was still needed even though only able to reach 10-25 NTU. URF and USSF contributed to higher efficiency of turbidity removal.

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