Slow Sand Filtration Research Articles

Efektivitas Kombinasi Slow Sand Filter Media Geotekstil dan Karbon Aktif untuk Menyisihkan Nilai Permanganat dan Total Coliform

The water of Kali Jagir, Surabaya, used as a raw water source, has been contaminated with high levels of BOD, COD, and permanganate. Therefore, this research seeks to address these issues by combining slow sand filtration with various media, including geotekstil and activated carbon. The study aims to optimize this combination in reducing parameters such as permanganate and total coliform in the raw water. The research methodology includes literature review, testing of raw water characteristics, preparation of slow sand filter reactors, preparation of filter media, and testing of media variations with an observation of organic and bacteriological pollutant removal efficiency. The results show that the combination of filter media involving sand, activated carbon, and geotekstil is effective in reducing organic pollutants. Geotekstil aids in the growth of the schmutzdecke layer and facilitates cleaning, while sand and activated carbon tend not to support such growth. Moreover, the optimum schmutzdecke growth time varies depending on the type of media used. These findings have significant implications for raw water treatment in industrial areas vulnerable to pollution, resulting in quality drinking water and addressing the frequent clogging issues in slow sand filters.

Training on Clean Water Treatment Using Slow Sand Filters And Biomass Filters at Bahrul Magfiroh Islamic Boarding School Malang City

The purpose of this activity is to increase students' knowledge about PHBS and diarrhea prevention using herbal ingredients as well as the application of clean water treatment simulations using slow sand filter and biomass filter methods. This method of implementing service uses a participatory and collaborative approach through active and interactive discussions. This activity was carried out by involving 54 students of Bahrul Magfiroh Islamic Boarding School Malang. Service participants directly practice and understand the function of applying water treatment devices and the use of herbal ingredients for the prevention of diarrhea. The results of activities on clean water treatment are almost 90% understood by students, both the use of biomass filters and slow sand filters, while 42.6% of students still have a low understanding of how to process herbal ingredients for the prevention of diarrhea. The importance of continuous training on increasing knowledge of clean and healthy living behavior must continue to be improved as an effort to prevent the risk of disease transmission and health problems, including maintaining personal health and the Islamic boarding school environment.

Development of Sasirangan Liquid Waste Treatment System Using Ozonization Method Using Composite Ceramic Filter Media Based on Water Chestnut (Eleocharis Dulcis)

Sasirangan Liquid Waste (SLW) contains heavy metals and chemicals with BOD and COD concentrations exceeding the waste water quality standards in accordance with the Minister of Environment and Forestry Regulation Number P.16 of 2019. The aim of this research is to design and develop a SLW processing system using filter media and composite ceramics made from water chestnut (Eleocharis dulcis). Based on previous research, using the filtration method; filtration and adsorption; filtration, adsorption, sedimentation and ozonization. Filtration method can remove solid particles and sediment from water, so the water appears clearer. The water purification process that involves a filtration method using slow sand filter (SSF), which additional processes are needed either before or after the SSF is carried out. Meanwhile, the use of water chestnut has been carried out by several researchers due to its high active carbon content, namely 50.68%. In this research, we combine several methods including filtration, sedimentation, and ozonization. Water chestnut has a bound carbon content of 84.53% after being activated with an H2SO4 activator, where the largest porosity is found in ceramics with activated charcoal composite materials with variations of the H2SO4 activator. Apart from that, chestnut also has a cellulose content of 35.32% so it has the potential to be effective as a ceramic composite material in sasirangan liquid waste processing filters, especially as an adsorbent. The benefits obtained from the results of this research can be a scientific reference for the use of water chestnut as a filter media and composite ceramic.

Evaluation of Water Treatment Efficiency of Full-Scale Slow Sand Filtration Process: Comparison of Summer and Winter Season

Objectives : The objective of this study is to evaluate the feasibility of sustainable operation in a conventional full-scale slow sand filter process.Methods : A slow sand filtration process was operated in small scale water treatment plants for valley water. The water quality such as particle matter, dissolved organic matter, the number of bacteria, and disinfection by-product (DBP) were monitored at four designated points once a week and was compared during summer (July-August) and winter season (December-January).Results and Discussion : Although the number of particle matter in summer was higher than in winter by 39% (2.91×10<sup>4</sup> /mL), particle matter in slow sand filter process was removed by 99% regardless of season (temperature). The removal efficiency of dissolved organic carbon (DOC) and UV<sub>254</sub> was higher in summer than in winter by 15% and 21%, respectively. In addition, concerning the organic fraction, higher molecular weight led to higher removal efficiency in the following sequence: BP (biopolymer, MW: 20,000 g/mol) > HS(humic substances, MW : 1,000~20,000 g/mol) > BB(building blocks, MW : 300~500 g/mol) > LMWs(low molecular weights, MW : 350 g/mol. The concentration of trihalomethanes (THMs) and haloacetic acids (HAAs), indicator of DBP, were detected at 12.2 and 9.4 μg/L in summer and 8.1 and 6.3 μg/L in winter, respectively, which would be considered very low concentration related to the drinking water regulation of 100 μg/L. Finally, the active bacteria was removed up to 93 and 92% in summer and winter, respectively.Conclusion : The feasibility of a slow filtration process was evaluated to compare particle and dissolved matter in summer and winter operation. Despite a 39% increase in particle matter in summer, the removal efficiency was maintained at 98% in summer and winter. Due to the increased activation of biofilm in summer, the removal of DOC and UV<sub>254</sub> was higher in summer than winter by 15 and 21%, respectively. The significant low concentration of THMs and HAAs, regardless of season, would be negligible. In addition, achieving over 92% removal of activated bacteria secured the biological safety. These stable operations ensure that slow filtration process is effective in controlling of water quality.

The Application of Slow Sand Filtration Technology for Improving Water Quality at Taman Gading Housing Area, Kaliwates District, Jember

Water is a basic need for all living organisms. Water quality implies living quality. Several parameters influencing water quality include minerals, dissolved organic substances, and turbidity. The water consumed must meet proven water quality standards. However, water quality still needs to be improved in several areas before consumption. The well water in residential areas placed on rice fields generally needs to meet the requirements for consumption. Many Taman Gading housing complex residents, especially in RW 036 RT 006, still use the well water to meet their daily needs. The well water quality in this area tends to be smelly and somewhat misty. Proper treatment is needed to improve the quality of well water in this area to reduce the negative impact on the population's health in the long term. This training focused on well water purification and filtration using slow sand filtration technology (SPL) to improve water quality. This method uses activated charcoal, sand, gauze, and pumice as filter media in specific proportions. The use of this method is effective and efficient in reducing the turbidity level of the sample water to the threshold for drinking water (<500 ppm), with a neutral pH (close to 7.00). This technology is effortless for residents to use and apply independently at a relatively low cost.

Performance of a modified and intermittently operated slow sand filter with two different mediums in removing turbidity, ammonia, and phosphate with varying acclimatization periods

The present study investigated the utilization of blood clam shells as a potential substitute for conventional media, as well as the influence of the acclimation time on the efficacy of an intermittent slow sand filter (ISSF) in the treatment of real domestic wastewater. ISSF was operated with 16 h on and 8 h off, focusing on the parameters of turbidity, ammonia, and phosphate. Two media combinations (only blood clam shells [CC] and sand + blood clam shells [SC]) were operated under two different acclimatization periods (14 and 28 d). Results showed that SC medium exhibited significantly higher removal of turbidity (p < 0.05) as compared to CC medium (45.99 ± 26.84 % vs. 3.79 ± 9.35 %), while CC exhibited slightly higher (p > 0.05) removal of ammonia (23.12 ± 20.2 % vs. 16.77 ± 16.8 %) and phosphate (18.03 ± 11.96 % vs 13.48 ± 12 %). Comparing the acclimatization periods, the 28 d of acclimatization period showed higher overall performances than the 14 d. Further optimizations need to be conducted to obtain an effluent value below the national permissible limit, since the ammonia and phosphate parameters are still slightly higher. SEM analysis confirmed the formation of biofilm on both mediums after 28 d of acclimatization; with further analysis of schmutzdecke formation need to be carried out to enrich the results.

Green wall system coupled with slow sand filtration for efficient greywater management at households

AbstractGreen walls are gaining attention for greywater management in the imminent terrestrial space and land constraint scenario. They have been tested primarily with greywater from a single source such as showers, hand or wash basins, laundry, and kitchen or a mix of a couple of these sources but barely with mixed greywater from all these household activities. Here, a green wall system coupled with a slow sand filter (SSF) was tested for managing household greywater. It consisted of a set of five serial hydraulic flow-connected reactors and an SSF unit. Each reactor housed an Epipremnum aureum sapling embedded in the support bed matrix, consisting of cocopeat and granular activated charcoal. The system operated at 150 cm d−1 hydraulic loading rate (HLR) achieved 90 ± 0.7%, 85 ± 4.5%, 72.9 ± 4.4%, and 60.6 ± 5.1% removal efficiencies for turbidity, chemical oxygen demand (COD), total nitrogen (TN), and total phosphorous (TP), respectively. The system maintained similar treatment performance with varying greywater strength when COD and TN were below ~400 and ~15 mg L−1, respectively. The polished effluent produced by SSF operated at 187 cm d−1 HLR, with characteristics &lt;5 mg L−1 COD, &lt;2 NTU turbidity, &lt;1 mg L−1 TN, ~0.5 mg L−1 TP, ~7.8 pH, and &lt;100 MPN per 100 ml fecal coliforms, qualifies the standards for non-potable reuse applications. Along with reclaimed water reuse, green walls provide environmental benefits by fixing CO2 in plant biomass. Overall, the low-cost system offers efficient greywater management in an eco-friendly way with minimized resource consumption and areal footprint.

Gallery well application as a media for water treatment in flooded areas (case study: Morowudi Village, Gresik Regency)

High-intensity rainwater is known to cause flooding in Morowudi Village, Gresik Regency. This is a major issue for the local community because flood-related to water quality degradation renders it unfit. This study aims to apply gallery wells made as an alternative media to treat floodwater with better-quality water in Morowudi Village, Gresik Regency. In this research, there are two media variations: silica sand or building sand with a diameter of 0.2–0.4 mm applied in the form of a reactor with a diameter of 0.8 meters and a media thickness of 60 cm, which used a separation technique. The separation technique mechanism of the gallery well is SSF (Slow Sand Filtration). The floodwater percolates slowly through a gallery well reactor, with the influent water penetrating from the outside reactor and congregating in the wall as the effluent. The effectiveness of artificial gallery well application is measured by the reduction percentage of TDS, total turbidity, and total coliform. The results showed that artificial gallery well application reduces of TDS, total turbidity, and total coliform in floodwater at Morowudi Village. Thus, it can be used as usable water for the local community.

The Use of Fly Ash and Bottom Ash to Reduce COD, TSS, and Color in Textile Industry Wastewater Effluent

The textile industry wastewater effluent contains some levels of COD, TSS, and color, it must be reprocessed as a tertiary treatment using the filtration method. The goal of this research was to examine the ability of fly ash and bottom ash as filtration media to reduce the pollutant / organic load of COD, TSS, and color in textile industry wastewater effluent. The slow sand filter method was used in this study, and the filter media was derived from coal combustion waste. The variation used in this study is a variation of filter media (fly ash and bottom ash), with fly ash diameters of 0.11 and 0.35 mm, bottom ash diameters of 0.85 - 1.50 mm, and media thickness of 1.50 - 2.00 mm (10 cm and 20 cm). The study’s findings demonstrated that using bottom ash and fly ash media in the filtration process with a slow sand filter system could maximize the efficiency of reducing COD, TSS, and color levels in textile industry wastewater effluent. In fly ash media, it can reduce COD, TSS, and Color by 90.58%, 81.87%, and 100%. Meanwhile, Bottom Ash filter media has an average COD, TSS, and Color reduction of 87.80%, 81.87%, and of 100%.

PEMANFAATAN SABUT KELAPA MELALUI METODE SLOW SAND FILTRATION UNTUK MEMENUHI KEBUTUHAN AIR BERSIH DI DESA TALANG TINGGI SELUMA

The sources of clean water is very important for everyone to support their life needs. However, Talang Tinggi Village, Seluma Regency has poor water supply conditions, indicated by the physical condition of the water which smells, the color is brown, and has sediment. This condition is getting worse because the source of water will be mixed with soil and mud. Talang Tinggi village does not have PDAM access yet, so the need for clean water only relies on natural water sources, swamp water and well water. This community service aims to overcome the problem of water resources in Talang Tinggi Village, Seluma Regency, Bengkulu Province by utilizing coconut fiber waste, as a filter media in the Slow Sand Filtration method. The results of the activity showed that there was a very significant improvement in water quality. The water that was cloudy and smelled becomes clearer and odorless. The value of acidity (pH) of the water sample also increased from 6.05-7.38 to 6.5-9.0. These results indicate that coconut fiber, which has been considered as waste, can be used to an effective filter for cleaning water.

System dynamic modelling to assess the influential factors affecting roughing filter and slow sand filter performance in treating culinary wastewater

This research aimed to determine the factors that influence the performance of a slow sand filter (SSF) equipped with a roughing filter (RF) as a pretreatment unit using system dynamic (SD) modelling. STELLA was used to model the system and predict the behavior pattern, as well as the system's performance in removing turbidity, total suspended solids (TSS), BOD, COD, and phosphate. SD modelling consisted of system identification, system model framework, model structure building, system modelling, verification, and validation. Two sub-models were obtained from the main model, consisting of the RF and SSF sub-models. Results showed that dissolved oxygen (DO) and the growth rate of microorganisms played significant roles in the parameter removal. Predicted result by SD modelling showed a good fit with actual run, suggesting that factors applied in the model building were adequate to exhibit the actual system. RF removed 80.5 %–85 % of turbidity and 70.63 %–85 % of TSS, while SSF removed 48.50 %–82.43 % of turbidity, 0.92 %–46.15 % of TSS, 1.65 %–65.45 % of BOD, 22.69 %–65.22 % of COD, and 7.96 %–27.11 % of phosphate. Effluent after SSF was still having BOD and COD concentrations exceeding the governmental standard, in which increasing DO inlet and microorganism growth rate were simulated afterward. The scenarios used showed a positive impact on the removal of BOD and COD, resulting in an average concentration lower than the permissible limit (5 mg/L and 50 mg/L, respectively).

Antibiotic resistance genes and the association with bacterial community in biofilms occurring during the drinking water granular activated carbon (GAC) sandwich biofiltration

The granular activated carbon (GAC) sandwich modification to slow sand filtration could be considered as a promising technology for improved drinking water quality. Biofilms developed on sand and GAC surfaces are expected to show a functional diversity during the biofiltration. Bench-scale GAC sandwich biofilters were set-up and run continuously with and without antibiotic exposure. Surface sand (the schmutzdecke) and GAC biofilms were sampled and subject to high-throughput qPCR for antibiotic resistance gene (ARG) analysis and 16 S rRNA amplicon sequencing. Similar diversity of ARG profile was found in both types of biofilms, suggesting that all ARG categories decreased in richness along the filter bed. In general, surface sand biofilm remained the most active layer with regards to the richness and abundance of ARGs, where GAC biofilms showed slightly lower ARG risks. Network analysis suggested that 10 taxonomic genera were implicated as possible ARG hosts, among which Nitrospira, Methyloversatilis and Methylotenera showed the highest correlation. Overall, this study was the first attempt to consider the whole structure of the GAC sandwich biofilter and results from this study could help to further understand the persistence of ARGs and their association with the microbial community in drinking water biofiltration system.

Evaluation of the Removal and Effects of Cylindrospermopsin on Ripened Slow Sand Filters.

The occurrence of toxic blooms of cyanobacteria has been a matter of public health interest due to the cyanotoxins produced by these microorganisms. Cylindrospermopsin (CYN) is a cyanotoxin of particular concern due to its toxic effects on humans. This study investigated the removal and effects of CYN in ripened slow sand filters (SSFs) treating water from Paranoá Lake, Brasilia, Brazil. Four pilot-scale SSFs were ripened and operated for 74 days. Two contamination peaks with CYN were applied along the filtration run. The improvement of any of the evaluated water quality parameters was not affected by the presence of CYN in the raw water. The SSFs efficiently removed CYN, presenting concentrations lower than 0.8 µg/L in the filtered water. The microbiota of the SSFs were dominated by protozoa of the genus Euglypha and amoebas of the genera Arcella, Centropyxis, and Amoeba, together with some groups of rotifers. These microorganisms played a crucial role in removing total coliforms and E. coli. In addition, CYN was not identified as a determining factor in the microbiota composition.

Enzymatic analysis in household intermittent slow sand filters as a tool for assessing biological clogging

Intermittent slow sand filters for household use have become an established technology that is efficient, simple, and affordable for water treatment. However, bio-clogging can seriously limit hydraulic efficiency and water quality in this treatment system. Therefore, the use of new techniques for studying clogging in slow sand filters has been proposed. This study aimed to evaluate biological clogging using an enzymatic approach, considering also hydraulic aspects and water quality. Six filtration columns with two different granulometric characteristics (fine sand and medium sand) were operated with a downward flow and intermittent flow regime for 120 days. The bio-clogging of the filter media was evaluated considering the presence of esterase enzymes through the degradation of fluorescein diacetate (FDA). So, daily raw and filtered water analyses were performed for physical and chemical characteristics and hydraulic monitoring. The two granulometric characteristics used did not significantly differ between physical and chemical aspects of water quality within the parameters analyzed. The filters showed an average efficiency of turbidity removal of 79.6 % and 80.5 % for fine and medium sand, respectively. The enzymatic assay revealed the existence of microbiological activity throughout the extent of the filters in both granulometric configurations used. The results indicated a potential risk of contamination of the filtered water. The FDA technique proved to be an exciting tool in evaluating biological clogging in intermittent slow sand filters.

Shedding light on the total and active core microbiomes in slow sand filters for drinking water production

Slow sand filters (SSF) are widely used in the production of drinking water as a last barrier in the removal of pathogens. This removal mainly depends on the ‘Schmutzdecke’, a biofilm-like layer on the surface of the sand bed. Most previous studies focused on the total community as revealed by DNA analysis rather than on the active community, which may lead to an incorrect understanding of the SSF ecology. In the current study, we determined and compared the DNA- (total) and RNA-displayed (active) communities in the Schmutzdecke layer from 10 full-scale slow sand filters and further explored the SSF core microbiome in terms of both presence (DNA) and activity (RNA). Discrepancies were observed between the total and the active community, although there was a consistent grouping in the PCoA analysis. The DNA-displayed community may be somewhat inflated, while the RNA-displayed community could reveal low abundance (or rare) but active community members. The overall results imply that both DNA (presence) and RNA (activity) data should be considered to prevent the underestimation of organisms of functional importance but lower abundance. Microbial communities of studied mature Schmutzdecke were shaped by the influent water. Nevertheless, a core microbiome was shared by the mature Schmutzdeckes from independent filters, representing the dominant and consistent microbial community composition in slow sand filters. In the DNA samples, a total of 33 VSC families (‘very strict core’, with a relative abundance >0.1% and 100% prevalence) were observed across all filters. Among the RNA samples, there were 18 VSC families, including 16 families that overlapped with the DNA VSC families and 2 unique RNA VSC families. The core microbial community structure was influenced by the operational parameters, including the Schmutzdecke age and the sand size, and was less influenced by water flow. In addition, indicator organisms (‘biomarkers’) for the Schmutzdecke age, which show the longest duration that SSF can maintain a good operation, were observed in our study. The abundant presence of bacteria belonging to bacteriap25 and Caldilineaceae was associated with older Schmutzdeckes, revealing longer periods of stable operation performance of the filter, while the high abundance of bacteria belonging to Bdellovibrionaceae and Bryobacteraceae related to short periods of stable operation performance.

The Effectiveness of Slow Sand Filtration on Reduction of Iron (Fe) and Calcium (CaCO3) Levels in Water

Ground water or well water is the largest source of clean water used. The most common obstacle in using groundwater is the problem of iron (Fe) and calcium (CaC03) content in raw water. This research aims to determine the effectiveness of slow sand filtration to reduce Fe and CaCO3 levels in water. This type of research is a pure experimental study in a re-treatment design (One Group Pretest Posttest). The samples of raw water were taken from water pump wells owned by residents on JI. Datu Adam, Lere Village. Sample testing after slow sand filtering was carried out at the UPTD Laboratory of the Office of Environment, Donggala. The filter was carried out with a medium thickness of 45 cm sand, 5 cm gravel sand, 7 cm gravel and 5 cm high puddle water. Before filtering the test results Fe 0.4mg/L and CaCO3 546.37mg/L. Based on the effectiveness test of slow sand filtration with 3 treatments, it was found that the levels of substances after filtering were iron (Fe) 0.29, 0.21 and 0.I2 mg/L respectively, while calcium (CaCO3) was 273.41, 241.35 and 210.11 mg/L respectively. From these results, slow sand filtration is effective in reducing Fe and CaCO3 levels in water. The community is expected to be able to use simple filtering media such as slow sand filters to reduce iron (Fe) and calcium (CaCO3) levels in water. It is also expected to provide additional knowledge studies in the field of public health, especially environmental health.

Development of nature-based sustainable passive technologies for treating and disinfecting municipal wastewater: Experiences from constructed wetlands and slow sand filter

There is an urgent need to develop low-cost technology for effective wastewater treatment and its further disinfection to the level that makes it economically useful. This work has designed and evaluated the various types of constructed wetlands (CWs) followed by a slow sand filter (SSF) for wastewater treatment and disinfection. The studied CWs were, CWs with gravels (CW-G), free water surface-CW (FWS-CWs), and CWs integrated microbial fuel cell (MFC) with granular graphite (CW-MFC-GG) planted with Canna indica plant species. These CWs were operated as secondary wastewater treatment technologies followed by SSF for disinfection purposes. The highest total coliform removal was observed in the combination of CW-MFC-GG-SSF which achieved a final concentration of 172 CFU/100 mL, whereas faecal coliform removal was 100 % with the combinations of CW-G-SSF and CW-MFC-GG-SSF, achieving 0 CFU/100 mL in the effluent. In contrast, FWS-SSF achieved the lowest total and faecal coliform removal attaining a final concentration of 542 CFU/100 mL and 240 CFU/100 mL, respectively. Furthermore, E. coli were detected as negative/absent in CW-G-SSF and CW-MFC-GG-SSF, while it was positive for FWS-SSF. In addition, the highest turbidity removal was achieved in CW-MFC-GG and SSF combination of 92.75 % from the municipal wastewater influent turbidity of 82.8 NTU. Furthermore, in terms of overall treatment performance of CW-G-SSF and CW-MFC-GG-SSF, these systems were able to treat 72.7 ± 5.5 % and 67.0 ± 2.4 % of COD and 92.3 % and 87.6 % of phosphate, respectively. Additionally, CW-MFC-GG also exhibited a power density of 85.71 mA/m3 and a current density of 25.71 mW/m3 with 700 Ω of internal resistance. Thus, CW-G and CW-MFC-GG followed by SSF could be a promising solution for enhanced disinfection and wastewater treatment.

Performance of slow sand filter reactor using geotextile for reducing total n and phosphate

Water pollution that occurs is mostly caused by industrial and domestic waste. One of the consequences of polluted water is the increase in total N and Phosphate which causes malfunction of animals and humans. This is a problem that needs attention to protect our life from the dangers of environmental pollution. Slow Sand Filter is an easy and inexpensive raw water treatment solution. The raw water used in this research is the Dungus Sidoarjo river. The acclimatization process was carried out for 14 days. Sand and gravel were used as filter media with a geotextile thickness of 0.2 and 4 cm. The sample is taken on the first, sixth, and twelfth days. The best reactor for reducing Total N and Phosphate is a reactor with a geotextile thickness of 0.2 cm (D2) on the first day of effluent taking, which is 84.5%, and a reactor with a thickness of 4 cm on the sixth day of effluent taking, which is 77%. The results of the One Way ANOVA test with a standard error (α) of 0.05 stated that there was no significant difference in the treatment of each reactor in reducing total N and Phosphate.

Water Characterization for Designing a WTP at Rural Village

Abstract: Many places in rural areas of Maharashtra are severely affected by water problems due to lack of efficient water supply system. It can be overcome by careful monitoring of water sources and proper treatment of water with efficient water supply systems. So it is planned to set up an efficient water treatment plant suitable for drinking water. For the WTP the site has been selected as Velneshwar, Guhagar, Ratnagiri. Preliminary survey, site survey, survey about current water sources in Velneshwar, waste water management, medical survey and population survey were taken for the information required while designing WTP. Also the various test are conducted to as experimental analysis. It deals with the design of various water features of water treatment plant at Velneshwar, Guhagar, Ratnagiri. Water from the 'Wadadai' well will be directed to the WTP near the site and by building an intake structure into which the water from the well will be drawn i.e. constructing intake, the water is properly treated by other components before being send. For design of WTP required units are intake, sedimentation cum coagulation and flocculation unit, slow sand filter, disinfection unit and elevated storage water tank will be designed.

Review of Slow Sand Filtration for Raw Water Treatment with Potential Application in Less-Developed Countries

Providing safe drinking water to people in developing countries is an urgent worldwide water problem and a main issue in the UN Sustainable Development Goals. One of the most efficient and cheapest methods to attain these goals is to promote the use of slow sand filters. This review shows that slow sand filters can efficiently provide safe drinking water to people living in rural communities not served by a central water supply. Probably, the most important aspect of SSF for developing and less-developed countries is its function as a biological filter. WASH problems mainly relate to the spread of viruses, bacteria, and parasites. The surface and shallow groundwater in developing countries around urban areas and settlements are often polluted by domestic wastewater containing these microbes and nutrients. Thus, SSF’s function is to treat raw water in the form of diluted wastewater where high temperature and access to nutrients probably mean a high growth rate of microbes and algae but probably also high predation and high efficiency of the SSF. However, factors that may adversely affect the removal of microbiological constituents are mainly low temperature, high and intermittent flow rates, reduced sand depth, filter immaturity, and various filter amendments. Further research is thus needed in these areas, specifically for developing countries.