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 Application of roughing filter to pre-treat 1,000 NTU raw water for slow sand filter

2019 ◽  
Vol 14 (2) ◽  
pp. 355-364 ◽  
Author(s):  
Yuichi Hashimoto ◽  
Hiroshi Takashima ◽  
Somasundaram Jayamohan
Keyword(s):  
Filtration Rate ◽  
Design Guidelines ◽  
Raw Water ◽  
Filter Media ◽  
Sand Filter ◽  
Treated Water ◽  
Slow Sand Filter ◽  
High Turbidity ◽  
Pre Treatment ◽  
One Year

Abstract It was confirmed experimentally that a Roughing Filter (RF) is effective as a pre-treatment system for Slow Sand Filter (SSF) with coagulant dosing and mixing with raw water. This RF system can pre-treat high turbidity raw water (1,000 NTU) to generate low turbidity (10 NTU) pre-treated water for SSF treatment. In the experiment, the types of filter media, height of the filter media, filtration rate and coagulant dosing were varied and the characteristics of each item were evaluated and the design guidelines were formulated. Water Treatment Plants (WTPs) consisting of pre-treatment with RF followed by SSF to treat river water were designed and constructed in Myanmar based on the design guidelines, and the operational performance was confirmed as effective to generate treated water with a turbidity under 5 NTU, which is in compliance with the WHO guideline despite the rather short working period of about one year. Sand scraping of SSF at a frequency of about once in every one to two months was implemented to maintain the design filtration rate.

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.

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.

Protection layers for the extension of slow sand filter running times in wastewater reuse

2002 ◽  
Vol 2 (1) ◽  
pp. 305-309
Author(s):  
H.-J. Mälzer ◽  
R. Gimbel
Keyword(s):  
Pressure Drop ◽  
Suspended Solids ◽  
Wastewater Reuse ◽  
Sand Layer ◽  
Sand Filters ◽  
Sand Filter ◽  
Running Time ◽  
Slow Sand Filter ◽  
Surface Filtration

The running time of slow sand filters in wastewater reuse is limited by the increase of pressure drop which is mainly caused by the surface filtration of suspended solids. Surface filtration mechanisms on the top of filter sand layer can be avoided e.g. by protection layers. Choosing suitable materials for protection layers a considerable extension of slow sand filter running times can be achieved.

Chemically enhanced gravel pre-filtration for slow sand filters: advantages and pitfalls

2006 ◽  
Vol 6 (1) ◽  
pp. 121-128
Author(s):  
C.C. Dorea ◽  
B.A. Clarke
Keyword(s):  
Negative Impact ◽  
Pilot Scale ◽  
Sand Filtration ◽  
Sand Filters ◽  
Slow Sand Filtration ◽  
Chemical Enhancement ◽  
Dissolved Organics ◽  
Efficiency And Effectiveness ◽  
Slow Sand Filter ◽  
Pre Treatment

The chemical enhancement of gravel (or roughing) filtration with coagulants, i.e. direct (gravel) filtration, has been proposed as a pre-treatment alternative for slow sand filters. However, studies have frequently focused on the efficiencies of the pre-filters in terms of reduction percentages. The effectiveness of the pre-treatment on the subsequent slow sand filtration is not usually cited or even evaluated. By incorporating a pilot-scale slow sand filter in our trials, both aspects of the pre-treatment process were assessed: efficiency and effectiveness. In terms of turbidity reductions, our results demonstrated that chemically enhanced pre-filtration was substantially more efficient (93.2 to 99.5%) than conventional pre-filtration (50.6 to 79.3); this was also observed in terms of reductions in the level of other parameters (i.e. thermotolerant faecal coliforms and dissolved organics). Yet, the use of a coagulant can have a negative impact on the slow sand filtration run.

scholarly journals Analysis of Clean Water Treatment with Slow Sand Filter Using Beach Sand and Quartz Sand

2021 ◽  
Vol 9 (2) ◽  
pp. 072
Author(s):  
Bintang Saptanty Artidarma ◽  
Laili Fitria ◽  
Hendri Sutrisno
Keyword(s):  
River Water ◽  
Quartz Sand ◽  
Total Coliform ◽  
Silica Sand ◽  
Beach Sand ◽  
Clean Water ◽  
Sand Filters ◽  
Sand Filter ◽  
Before And After ◽  
Slow Sand Filter

AbstractThe purpose of this study is to analyze the quality of Kapuas River water before and after processing and to analyze the comparative effectiveness of beach sand and quartz sand in slow sand filters with the thickness is 110 cm for processing Kapuas River water. The research method that used is the down flow method. The parameters that measured were pH, Turbidity, TDS, Organic Substances, Fe, and Total Coliform. The initial pH parameter is 5.6 and the results of filtering with beach sand 1, beach sand 2, silica sand 1, and silica sand 2 are 7; 6.9; 7,1; 6.9. The initial turbidity parameter was 35.2 and the filtering result are 1.21; 1.7; 16.0; 2.87. The initial TDS parameter was 122.4 and the filtering result was 90.5; 88.1; 127.5; 80.5. The initial Organic Substance parameter was 102.71 and the result after filtering was 77.92; 63.82; 98.99; 98.17. Keywords: beach sand, clean water, slow sand filter, quartz sand AbstrakTujuan Penelitian ini untuk menganalisa kualitas Air Sungai Kapuas sebelum maupun sesudah pengolahan dan menganalisa perbandingan efektivitas pasir pantai dan pasir kuarsa pada Saringan Pasir Lambat (SPL) dengan ketebalan 110 cm dalam mengolah air Sungai Kapuas. Metode penelitian yang digunakan adalah metode down flow. Parameter yang diukur adalah pH, Kekeruhan, TDS, Zat Organik, Kadar Fe, dan Total Coliform. Parameter pH awal 5,6 dan hasil penyaringan dengan pasir pantai 1, pasir pantai 2, pasir silika 1, dan pasir silika 2 adalah 7; 6,9; 7,1; 6,9. Parameter Kekeruhan awal 35,2 dan hasil penyaringan adalah 1,21; 1,7; 16,0; 2,87. Parameter TDS awal 122,4 dan hasil penyaringan adalah 90,5; 88,1; 127,5; 80,5. Parameter Zat Organik awal 102,71 dan hasil penyaringan adalah 77,92; 63,82; 98,99; 98,17. Kata Kunci: air bersih, pasir kuarsa, pasir pantai, saringan pasir lambat

scholarly journals Teknologi pengolahan air gambut menjadi air bersih dengan sistem koagulan dan filtrasi di Desa Buluh Cina, Kecamatan Siak Hulu, Kampar

2019 ◽  
Vol 1 ◽  
pp. 325-332
Author(s):  
Juandi Juandi M ◽  
Usman Malik ◽  
Salomo Salomo ◽  
Antonius Surbakti
Keyword(s):  
Ph Value ◽  
Organic Content ◽  
Clean Water ◽  
Sand Filters ◽  
Sand Filter ◽  
Optimal Filtration ◽  
Slow Sand Filter ◽  
Service Activity ◽  
Water Ph ◽  
Filtration Technology

The abundant peat water in Buluh Cina Village, Siak Hulu Subdistrict, Kampar is a natural potential that can be used for cooking and bathing purposes by processing peat water into clean water that is suitable for consumption. The purpose of this service activity is to treat peat water into clean water. The method used in this service activity is using coagulant and filtration technology. The optimal filtration and coagulant media used for peat water treatment consists of biosand filters with two media namely pumice and quartz sand. The dedication results reduce turbidity and color of peat water and reduce organic content, so that peat water is processed into clean drinking water. The lowest pH value before filtering is equal to 5.93 and the highest pH is found before filtering which is 6.23. This means that before filtering peat water is weak acidic. The lowest sample results after filtration with a slow sand filter that is equal to 6.42 and the highest pH after filtration of 7.5, which means that water is weakly basic. A good pH limit for water is 6.5 to 8.5 so this service proves that slow sand filters are considered effective enough to optimize water pH. Total dissolved solids (TDS) is one of the parameters for determining water quality, TDS shows the amount of solute solids in water. The result of peat water TDS is that the lowest TDS value before filtration is 46 mg / L and the highest TDS is found before filtering which is 49 mg/L. The lowest sample results after filtration with slow sand filter is 49 mg / L and the highest TDS after filtering is 83 mg/L.

Protection layers for the extension of slow sand filter running times in wastewater reuse

2006 ◽  
Vol 6 (1) ◽  
pp. 105-111 ◽  
Author(s):  
H.-J. Mälzer ◽  
R. Gimbel
Keyword(s):  
Pressure Drop ◽  
Suspended Solids ◽  
Wastewater Reuse ◽  
Sand Layer ◽  
Sand Filters ◽  
Sand Filter ◽  
Running Time ◽  
Slow Sand Filter ◽  
Surface Filtration

The running time of slow sand filters in wastewater reuse is usually limited by the increase of pressure drop which is mainly caused by surface filtration effects of suspended solids. Surface filtration mechanisms on the top of filter sand layer can be avoided e.g. by so-called protection layers. By choosing suitable materials for protection layers a considerable extension of slow sand filter running times can be achieved.

scholarly journals Carwash wastewater treatment using the chemical processes

2021 ◽  
Author(s):  
Giti Kashi ◽  
Shahrbanou Younesi ◽  
Alireza Heidary ◽  
Zeinab Akbarishahabi ◽  
Babak Kavianpour ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
High Efficiency ◽  
Oxygen Demand ◽  
Chemical Processes ◽  
Special Focus ◽  
Chemical Methods ◽  
High Turbidity ◽  
Pre Treatment ◽  
High Chemical Oxygen Demand

Abstract Carwash is known as one of the most important urban services bring about production of huge volume of wastewater with high turbidity and high chemical oxygen demand (COD). Seasonal and carwash location features affect the quality of carwash wastewater. Various methods with special focus on chemical processes have been employed for carwash wastewater treatment and eliminating different pollutants from this wastewater of great concern for the environment. This review was conducted for identifying and comparing the efficiency of chemical processes for carwash wastewater treatment. To this aim, key words were identified and a search protocol was defined to search studies in three databases: Scopus, Web of Science, and PubMed. The results of this systematic review indicated that coagulation (66%) is the most common chemical processes for carwash wastewater treatment. Although chemical processes are able to reduce the turbidity and COD over 80%. Due to the characteristics of carwash wastewater, chemical processes are a necessary pre-treatment for processes such as membrane technology. Rapid treatment and high efficiency are the advantages of wastewater treatment by chemical methods, but the energy consumption and sludge volume are two main factors in selection the chemical processes for carwash wastewater treatment.

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.

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