Oct. 07, 2024
This study was conducted in Kambata Tambaro zone, in Hadaro and TuntoWoredas, three selected kebeles, namely Ajora, Tunto and Lalo. Kambata Tabaro zone that found approximately 247 km south-west of Addis Ababa, capital city of Ethiopia. The whole Kambata Tambaro zone is found between 500 and meters above sea level and its topography is characterized by steep slope at the foot of Anbericho, Dato and Ketta Mountains. The zone is boarded on the south by Wolaita, on the southwest by Dawro, on the northwest by Hadiya, on the north by Gurage zones and on the east by Halaba special woredas.
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Clay soils were collected from Ajora, Tunto and Lalo sits. The collected clay soils were packed, labelled and transported to the drying place. The clay soils were combined with equal proportion and dry in the sun for 7 days with guidance of the local potters. The clay was grounded with wooden mortar and pestle and screened with 0.5 mm sieve size. The saw dust was collected from local furniture manufacturers. After drying for 7 days it was processed through wooden mortar and pestle like clay. The saw dust was screened with 0.5 mm opening sieve. Grog was grounded with mortar, pestle and sieved using 0.5 mm sieve size.
The burned material (sawdust) and grog were mixed for 40 min in dry condition with different proportion. Water was added uniformly on a dry mixture of clay, saw dust and grog and mixed by wedging and rolling for 40 min to get a smooth homogeneous mixture. Finally, it was divided into blocks as shown in the Table 1 (Kabagambe ). Ceramic filters were designed in shape of a flower pot, disc, and candle.
Table 1 The percentage composition of clay, sawdust and grogFull size table
Clay mixtures were moulded into flower pot shape in a plastic cup. The pots were pressed to the wall of about more than 1 cm thickness. The press filter materials were dried in open air for 3 days and on a drying place for 10 days to remove excess moisture which can cause the filter to crack during the firing process (Babafemi and Yinusa ).
Firing was used to produce dense materials and components from ceramic powders by applying thermal energy. After the block clay mixtures were moulded into flowerpot shapes in the desire size, the sun dry filter pots were fired in the furnace at different temperature. Different batch of press dry ceramic filters are place in a muffle furnace and sinter for 5 h at 700 °C, 750 °C and 800 °C with 10 °C heating and cooling rates for 5 h. Filter code 1, 4 and 7 were fired at 700 °C, filter code 2, 5 and 8 were fired at 750 °C and filter code 3, 6 and 9 were fired at temperature of 800 °C (Table 1) (Joong and Kang ).
Contaminated river water samples were collected from Hadaro Sana River by using standard sampling techniques according to Ilkeret al. (). Grab samples of the source water were collected with cleaned sterile plastic container and filled in large plastic container, then, transported to laboratory and refrigerated.
Flow rate was measured with water taken from the same source Sana River. Source water was filled continuously in the filter elements on testing day and other water quality parameters were tested in the same day. The filter elements made in the above procedure were soaked in pure distilled water at least for 8 h for effective and constant flow rate determination in measuring the flow rate of filter elements. It was tested by measuring the amount of water that was percolated after 1 h. The water that pass through the filter flowerpots were collected in polyethylene plastic cup then the time and discharged water were recorded on the filter log (Martins ). The average flow rates were monitored throughout production. The filter elements were cleaned immediately after testing with distilled water.
Sana river water was contaminated with indicator microorganisms. This water was diluted with sterilize water at 110 °C in 1: ratio by taking 1 mL of the river water and diluted with 999 mL sterilize water. The common indicator microorganisms used were E. coli and total coliform. A membrane filtration technique was used to detect and enumerate total coliform and E. coli from both source water and filtered water samples. The membrane in membrane filtration has uniformly sized holes or pores of diameter 0.45 μm. This pore size is slightly smaller than the diameter of typic, meal total coliform or other bacteria of interest. As the water sample was drawn through the filter, pure water passed through the pores, but the total coliform, E. coli and anything larger in size than 0.45 μm were caught on the surface or trapped in the pores of the membrane. The filters were tested for the removal efficiency of microbiological indicators (total coliform and E. coli).
Filter paper with 0.45 μm pore size was placed on the filter support base by using sterile tweezers. The whole apparatus was moved in a swirling motion to stir the sample by pouring 100 ml of the diluted river water. Filtration was sprinted and the funnel was rinsed with about 30 ml of distilled water twice. The filter membrane was removed carefully with sterilized tweezers and the membrane was then transferred to Membrane Lauryl Sulphate Broth media on metal Petri dish for in a rolling motion. The Petri dishes were inverted and placed into incubator set at 32 °C and 40 °C for 16 h for growth of colony of total coliform and E. coli.
The number of coliform forming units (CFU) were counted under magnifying glass and were expressed as CFU/100 ml. Microbial removal efficiency were calculated in terms of percent removal efficiency by the following formula.
$${\text{\% Removal efficiency }} = \frac{C\, before - C \,after}{C\, before } \times 100$$
(1)
where C influent microbial concentration in the raw water sample (cfu/100 mL) effluent: microbial concentration in the filtered water sample (cfu/100 mL).
Turbidity of the water in the influent and effluent water samples were tested by using portable turbidity mete (CL52 D NEPHELOMETER). Turbidity removal efficiency of the ceramic filters was evaluated by using the same river water. Turbidity of the water samples was measured relative to the turbidity of distilled water having turbidity 2NTU. A small volume of 15 ml of the sample was placed in the sample cell bottle. The exterior surface of the bottle was wiped clean of fingerprints with the provided cleaning cloth before placing in the turbidity meter. First, the turbidity of source water was tested for turbidity before being filtration. Then the source water was passed through different filters. The effluent water turbidity was tested after passing through the developed filters.
Finally, the turbidity reduction was calculated by the following formula.
$${\text{Turbidity}}\left( {\text{\% }} \right) = \frac{Turbidity\, of\, source\, water - Turbidity\, of\, filtered\, water}{Turbidity\, of\, source\, water } \times 100\%$$
(2)
Water hardness removal efficiency of the ceramic filter elements were evaluated with complexation titration method by using EDTA and eriochrome black T (EBT) as an indicator. The concentration of calcium and magnesium cations that cause for the hardness of water were measured using complexometry titration in the laboratory prepared solution. 0. M magnesium solution was prepared by dissolving weighted 4.6 g MgCl2·6H2O in 500 mL conical flask with distilled water and transferred to mL volumetric flask and filled with distilled water up to the mark. Calcium chloride solution was prepared from 1.1 g of solid CaCl2 dissolving in a beaker of 500 mL with distilled water then transferred to mL volumetric flask and filled with distilled water up to the mark.
The titrant 0.01 M EDTA solution was prepared by weighing 3.72 g of EDTA sodium salt dried at 80 °C and dissolved in 500 mL beaker then transferred to mL volumetric flask and filled up to mark. EDTA solution was standardised with prepared primary standard solution of CaCO3. An approximately 0.01 M solution of EDTA was prepared by dissolving 3. g EDTA in distilled water and diluted to 1 L and the solution was standardized with standard calcium carbonate solution complexometrically. EBT solution was prepared by dissolving 0.2 g of EBT indicator in 15 mL ammonia solution and 5 mL absolute ethanol. Buffer solution of pH&#;=&#;10 was prepared by adding weighed 17 g of NH4Cl in 142 mL concentrated ammonia solution (sp. gravity of 0.9) and diluting to 250 mL with distilled water in a conical flask. To prepare a buffer solution of pH&#;=&#;10, 70 g of ammonium chloride was dissolved in 570 mL of ammonium hydroxide (sp gr. 0.90) and marked up the volume to mL with distilled water in a volumetric flask (Birendra and Pandey ).
The titration was carried out at a pH of 10, in an NH3&#;NH4+ buffer, which keeps the EDTA (H4Y) mainly in the half-neutralized form, H2Y2&#; where it complexes the Group IIA ions very well but does not tend to react as readily with other cations such as Fe3+ that might be present as impurities in the water.
From the collected filtered water through each of the ceramic filters 20 mL of the sample was pipated in a clean 250 mL conical flask for each trial and 2 mL of ammonia buffer solution followed by 1 mL of EBT then titrated with EDTA solution. The concentration of metal ion was calculated from 1:1 mol ratio of EDTA and metal ion. The concentrations of the cations were calculated in the samples as (ppm) and finally the removal efficiency of the ceramic filters was evaluated for each code of filter elements. The equation for the reactions that occur at end point of the titration is as follows:
$${\text{H}}_{ 2} {\text{Y}}^{ 2- } \left( {\text{aq}} \right) \, + {\text{ MgIn}}^{ - } \left( {\text{aq}} \right) \, \to {\text{MgY}}^{ 2- } \left( {\text{aq}} \right) \, + {\text{ HIn}}^{ 2- } \left( {\text{aq}} \right) \, + {\text{ H}}^{ + } \left( {\text{aq}} \right)$$
(3)
Wine red sky bluewhere; H2Y2&#; is EDTA, HIn2&#; is an indicator, MgIn&#; is metal indicator, MgY2&#; is metal EDTA complex. For the determination of Ca2+ small amount (0.1 g) of magnesium chloride was added in the EDTA because the CaIn&#; is not very stable and the presence of Mg2+ in the solution ensures a sharp end point through the complexation of the EBT indicator with the magnesium ions present.
The iron removal efficiency of ceramic filters were performed with single beam UV&#;visible spectrophotometer (XP-P, china, number to ) for water sample taken from Sana river. It was tested in Hawassa University Environmental Enginering Laboratory. In the iron determination, stock solution of Mohr&#;s salt [Fe(NH4)2(SO4)2·6H2O] ppm was prepared by dissolving 6.97 g of the salt in 500 mL beaker then transferred to mL volumetric flask and filled to the mark. Standard solutions at different concentrations (100 ppm, 10 ppm, 8 ppm, 6 ppm, 4 ppm and 2 ppm) were prepared from stock solution for the calibration of UV&#;visible spectrophotometer instrument. The concentration of 1,10 phenanthroline was 3 times the concentration of Mohr&#;s salt because 1 mol of Mohrs salt forms orange red color complex [(C12H8N2)3Fe]2+ with 3 mol of 1,10 phenanthroline as shown the color in Fig. 1.
Fig. 1Magnesium, calcium, sulphate and phosphate removal efficiency %
Full size image
The absorbance of the red complex produced was measured with a spectrophotometer at a wavelength of 510 nm. Hydroxylammonium chloride is used as a reducing agent for the conversion of iron (III) to iron (II) in the solution.
Before UV determination 1 mL HCl, 5 ml hydroxyl ammine, 3 ml sodium acetate, 5 ml 1,10 phenanthroline were added by taking 10 ml solution from each of the standard solution and blank solution then the solutions were filled up to mark with distilled water in 100 ml volumetric flask.
The same procedure was followed for the source water (before filtration) and filtered water (after filtration) by taking 5 mL and 10 mL water respectively then filled up to the mark with distilled water. After 1 h, the UV&#;visible spectrophotometer instrument was calibrated with standard solution of different concentration and blank solution the absorbance of the source water and filtered water was measured and the concentration was calculated with (ppm) based on the equation of the standard solution from the calibration graph at 510 nm.
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Featured content:The nitrite test was conducted in Analytical chemistry laboratory of Hawassa University using single beam UV visible spectrophotometer (XP-P, china, number to ). The laboratory prepared solution of 0.01 M NaNO2 was used to percolate through the ceramic filters and to analyze the removal efficiency of the ceramic filter elements. The stock solution of ppm was prepared dissolving 1.456 g sodium nitrite in mL volumetric flask and filled to the mark with distilled water. The standard solutions of (100 ppm, 10 ppm, 8 ppm,6 ppm, 4 ppm and 2 ppm) were prepared from stock solution for standardization of the instrument. Solution of 0.025 M Paranitroaniline and 0.025 M 1-naphthol were prepared from the mass of 1.726 g paranitroanilin and 1.802 g of 1-naphthol by dissolving in mL volumetric flask and filled up to the mark separately. Nitrite under acidic conditions is go through diazotisation with paranitroaniline in ice bath and is formed violet colored complex with 1-naphthol under basic condition. All the chemicals used were analytical reagents.
Conductivity analysis of the source river water and the filtered water through the ceramic elements were performed with Conductivity Meter. The pH of similar source water and filtered water were analyzed with pH-016 pH METER. For conductivity test, standard solution of KCl was prepared with concentration and conductivity of 0., 0. and 0. ppm to confirm the suitability of the instrument. The pH value of 4 and 8 buffer solutions were used to sustain the measurement of pH of the source and filtered water.
Porosity of the ceramic filters was determined using the water absorption test (direct) method. It was a destructive method because three different samples weighing (50 g, 60 g and 100 g) were taken and the average porosity of these three samples was the apparent porosity of a ceramic filter. The samples were weighed when dry in air then saturated in distilled water at room temperature for 20 h. The water with the samples was then boiled for about two hours and allowed to cool to room temperature for another 20 h. This was done to ensure that the air in the open pores of the filter samples was replaced by the distilled water. The soaked samples were weighed under distilled water then removed and surface wiped with tissue paper and weighed in air. The weight of the wire was subtracted from the value obtained while determining the weight of the sample suspended in water. Apparent porosity (P) was then calculated using the expression given below (D&#;ujanda ).
$$P = 100\left[ {\frac{Wsaturate - Wdry}{Wsaturate - Wunderwater}} \right]$$
(4)
where; Wsaturated is the weight of the specimen when saturated in water, W dry is the weight of the dry specimen and Wunderwater is the weight of the sample underwater.
Data analyses were performed with the statistical analysis system (SAS Institute ). The data generated on efficiency of ceramic filtrates made from different proportion of saw dust, grog and clay were subjected to analysis of variance (ANOVA) using the general linear model procedure. Least significant (LSD) test was used to determine the differences among the efficiency of ceramic filtrates based on the level at P&#;=&#;0.05.
Ceramic water filters (CWF) are an inexpensive and effective type of water filter that rely on the small pore size of ceramic material to filter dirt, debris, and bacteria out of water. This makes them ideal for use in developing countries,[1] and portable ceramic filters are commonly used in backpacking.[2]
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Similar to other methods of filtering water, the filter removes particles larger than the size of the pores in the filter material.[3] Typically bacteria, protozoa, and microbial cysts are removed. However, filters are typically not effective against viruses since they are small enough to pass through to the "clean" side of the filter. Ceramic water filters (CWF) may be treated with silver in a form that will not leach away. The silver helps to kill or incapacitate bacteria and prevent the growth of mold and algae in the body of the filter.
Ceramic filtration does not remove chemical contaminants, per se. However, some manufacturers (especially of ceramic candle filters) incorporate a high-performance activated carbon core inside the ceramic filter cartridge that reduces organic and metallic contaminants. The active carbon absorbs compounds such as chlorine. Filters with active carbon need to be replaced periodically because the carbon becomes clogged with foreign material.
Pot-type ceramic water filter dispensing clean water into a glass.The two most common types of ceramic water filter are pot-type and candle-type filters. Ceramic filter systems consist of a porous ceramic filter that is attached to, or sits on top of a plastic or ceramic receptacle. Contaminated water is poured into a top container. It passes through the filter(s) into the receptacle below. The lower receptacle usually is fitted with a tap.
Contaminants larger than the minute holes of the ceramic structure will remain in the top half of the unit. The filter(s) can be cleaned by brushing them with a soft brush and rinsing them with clean water. Hot water and soap can also be used.
In stationary use, ceramic candles have mechanical, operational and manufacturing advantages over simple inserts and pots. Filter candles allow sturdy metal and plastic receptacles to be used, which decreases the likelihood of a sanitary failure. Since their filter area is independent of the size of the attachment joint, there is less leakage than other geometries of replaceable filter, and more-expensive, higher-quality gaskets can be used. Since they are protected by the upper receptacle, rather than forming it, they are less likely to be damaged in ordinary use. They are easier to sanitize, because the sanitary side is inside the candle. The non-sanitary part is outside, where it is easy to clean. They fit more types of receptacles and applications than simple pots, and attach to a simple hole in a receptacle. They also can be replaced without replacing the entire upper receptacle, and larger receptacles can simply use more filter candles, permitting filter manufacture to be standardized. If a filter in a multifilter receptacle is found to be broken, the filter hole can be plugged, and use can continue with fewer filters and a longer refill-time until a replacement can be obtained. Also, standardizing the filter makes it economical to keep one or a few filters on hand.
There are also portable ceramic filters, such as the MSR Miniworks, which work via manual pumping, and in-line ceramic filters, which filters drinking water that comes through household plumbing. Cleaning these filters is the same as with the clay pot filter but also allows for reverse-flow cleaning, wherein clean water is forced through the filter backwards, pushing any contaminants out of the ceramic pores.
The major risks to the success of all forms of ceramic filtration are hairline cracks and cross-contamination. If the unit is dropped or otherwise abused, the brittle nature of ceramic materials can allow fine, barely-visible cracks, allowing larger contaminants through the filter. Work is being done to modify clay/sawdust ratios during manufacture to improve the brittle nature and fracture toughness of these clay ceramic water filter materials.[4] If the "clean" water side of the ceramic membrane is brought into contact with dirty water, hands, cleaning cloths, etc., then the filtration will be ineffective. If such contact occurs, the clean side of the filter should be thoroughly sterilized before reuse.
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Modern ceramic water filter pot, manufactured by MSABI.Henry Doulton invented the modern form of ceramic candle sanitary water filter in . In , Queen Victoria commissioned him to produce such a device for her personal use. By , Doulton ceramics was widely recognized as a premier manufacturer of an effective prevention device for treating infective water. In , Doulton was knighted, in part for his work with water filters. Louis Pasteur's research concerning bacteria also had provided a demonstrable reason for the filters' effect. Doulton's original organization for water filters remains in existence, although it has been sold and renamed several times. "Doulton" is currently () a registered trademark of Fairey Ceramics.[5]
Several universities including MIT; Universities of Colorado; Princeton University; University of Wisconsin-Milwaukee; The Ohio State University; Universities of Tulane, West Virginia, North Carolina in the US; University of Delft, Strathclyde in Europe, USAID, UNICEF, Zamorano University in Honduras, Rafael Landívar University in Guatemala, Earth University, Institute of Hydraulic resources, the Red Cross, Engineers Without Borders, United Nations, countries in Africa like Nigeria, Ghana, Burkina Faso, Kenya, etc. and countries in Asia like Nepal, Bangladesh, Cambodia, Sri Lanka, India, Vietnam, Uganda etc. and NGOs are supporting the expansion of the use of ceramic filters in drinking water development initiatives; most commonly, in the form of clay pot filters.[6]
Fernando Mazariegos of Guatemala was responsible for developing Ceramic Pot Filter technology in while Director of Water Research at the Central American Research Institute in Guatemala City. He was the Director of Research and Development at Ecofiltro in Antigua, Guatemala. Ron Rivera studied under Fernando Mazariegos of Guatemala and was a key proponent and innovator in the field as part of the group to take the ceramic frustum shaped(pot) filter across international borders and helped developing nations to provide cheap high quality potable water. Ron Rivera also worked with Potters for Peace worldwide for the good and benefit of clay workers in developing nations to sustain their businesses. [7]
The latest development is in India, NGOs such as Enactus IIT Madras, Rupayan Sansthan, Sehgal Foundation are supporting the expansion and use of indigenized frustum shaped ceramic water filters called Matikalp for drinking water development initiatives in Tamil Nadu, Rajasthan, Bihar and other states.[8][9]
In Africa, Uganda Spouts of Water works in collaboration with local communities and partners to produce and distribute ceramic water filters (Purifaaya) made from locally available materials.
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