Sand Filtration Research Articles

Evaluation of crushed slates as a suitable capping material for rapid gravity sand filters

In the potable water treatment process, Rapid Gravity Sand Filters (RGSF) are commonly adopted as the last solid-liquid separation stage. Cleaning of the RGSF is done through backwashing. RGSF is widely adopted all over the World due to its ease of operation and high filtration rates. However, these filters suffer from stratification of the sand media, which causes floc removal to occur only at the topmost layer of the filter bed, leaving the remaining depth unutilized. Capping is a technique whereby a thin layer of sand filter media is replaced with a suitable coarse material to overcome the problem of stratification and transform a singlemedia RGSF into a dual-media filter. The objective of this study is to determine the suitability of crushed slates as a capping material. The study evaluated the performance of a crushed expanded slate-capped filter against a conventional single-media RGSF, the effects of its physical and chemical characteristics, and varying the depth of the capping material. Laboratory tests were conducted to assess the physical and chemical characteristics of slates from Maji ya Chumvi (Coast, Kenya). This included specific gravity, acid solubility, water extractable substances, silica content, and friability. A performance comparison was carried out by means of a fabricated model filtration unit set up within an existing community water treatment plant. The model filtration unit was fed with pretreated raw water of varying influent turbidities. Crushed expanded slates met the minimum physical and chemical requirements for use as a capping material for RGSF. The crushed expanded slate-capped RGSF model demonstrated high robustness under high shock turbidity loads (above 150 NTU), which is illustrated by an increased length of filter run of 27% (50–150 NTU) and 45% (150–300 NTU). Increasing the depth of capping material from 25mm to 50mm did not yield any significant improvement or deterioration in the filter run length. At influent turbidities below 150 NTU, the effluent water quality for all three scenarios (uncapped, 25 mm, and 50mm crushed expanded slates capped) is below 5 NTU and therefore meets the Kenyan drinking water standards. Above 150 NTU influent turbidity, the effluent water quality for the uncapped RGSF deteriorates, whereas for the 25mm and 50mm capped RGSF, it remains consistently below 5 NTU. This demonstrates the usefulness of the crushed expanded slates in improving the turbidity removal of RGSF for high (above 150 NTU) turbidity loads. This study recommends a full-scale trial of crushed expanded slates to facilitate a more precise estimation of the overall benefit of full-scale community water filtration systems.

Process for nutrient recycling from intensive aquaculture through microalgae-bacteria consortium

This work studies a biological process based on a microalgae-bacteria consortium for recycling nutrients in a recirculating aquaculture system (RAS) implanted in an intensive marine aquaculture farm. Additionally, some techniques were used for microalgae biomass harvesting and tested the effectiveness of filtration by a column with multi-layer sand to reduce the solids concentrations in the effluent.The consortium was grown in photobioreactors in batch and semi-continuous operation modes using the solids concentrated stream generated in the RAS system. The semi-continuous operation showed a high percentage of TDN and TDP removal, achieving final concentrations of 1.09 ± 0.02 mg·L−1 and 0.01 ± 0.01 mg·L−1, respectively, while DOC was reduced to 3.87 ± 0.06 mg·L−1. The values of productivity 44 ± 9 mg TSS·L−1 indicated that the studied stream is a suitable culture medium for the growth of the microalgae-bacteria consortium.A combination of harvesting techniques was studied, coagulation-flocculation-settling and coagulation-flocculation-flotation. The first step was to optimise the dose of FeCl3 through the coagulation-flocculation test to pre-concentrate the biomass generated, achieving an optimal dose of 0.106 mg Fe·mg TSS−1. Then, two separation processes were applied to the stream and compared: settling and flotation. The maximum removal efficiency (90.2 ± 0.3 %) was obtained in the settling process, so the coagulation-flocculation-settling was select as the best combination of harvesting techniques.Finally, sand filtration was studied as an effluent refining process to improve solids reduction of the water obtained in the harvesting step resulting in an effluent with 17.18 ± 1.49 mg TSS·L−1.The proposed sequence process is capable of recycling nutrients from an intensive marine aquaculture farm by using these resources via transformation into microalgae biomass and generating quality effluent.

Feasibility of electrochemical methods as pre-treatment in desalination

Growing population hand in hand rapid industrialization lead to decay of fresh water sources. Satisfying water needs to capita became a serious challenge making nations look in to. Thanks to reverse osmosis technology which made possible of tapping water from sea. Round the world RO is will accepted technology for quenching needful water. The efficacy decrement aspects of RO are scaling, particulate fouling, bio-fouling and organic fouling. To abate fouling, in use methods such as, coagulation/flocculation, sand filtration, adsorption (Granular Activated Carbon/Powdered Activated Carbon), ozonisation, microfiltration or ultrafiltration are used as pre-treatment methods. Nevertheless, these methods possess some drawbacks therefore an attempt has been made listing feasible electrochemical methods as pre-treatment to nullify these drawbacks.

The Effect of Treated Sulfur Water on the Microbial Content of the Soil and the Extent of Resistance of These Bacteria to Antibiotics

The research began on March 7, 2021, as the regions of Ain Al-Wusta and Ain Jarura were chosen to take soil samples. The sulfuric water was treated using laboratory batch reactors. Locally manufactured glass tubes were used, with dimensions 17 * 17 * 55 in length, width and height, respectively, Subsequently, microbiological and chemical analyzes of the soil were performed. The results of the study showed success of the physical treatment process that was used to reduce the levels of sulfur in the water Depending on the source of water and the type of material used, the triple-magnetic treatment achieved the highest removal rate of 73% in Ain Al-Wusta soil, 40% in soil sample B1, and 27% in soil sample B2 of Ain Jarura. The results of bacterial culture showed that Gram-negative bacteria were dominant by 100% in soil samples from Ain Jarura region treated with untreated sulfuric water (WA1, WA2, WA3) (Table- 4), as well as for the same soil samples treated with sulfuric water treated with sand filter (GB1), charcoal filter (GB2) and magnetic field filter. (GB3) Soil samples treated with untreated sulfur water were dominated by Pseudomonas aeruginosa with a percentage of 66.7% and Acinetobacter lwoffii with a percentage of 33.3%.The results of the bacterial count of soil samples from the Ain Jarura region showed that there were significant differences between the bacterial number with sulfuric water treated with the three filters, As for soil samples from Ain Al-Wusta region, only soil samples added to sulfuric water treated with charcoal filter (WB2) gave significant differences with a significant decrease of number (84×102 CFU) for the species Aerococcus viridans. The results of the antibiotic sensitivity test showed that Elizabethkingia meningoseptica gave the highest rate of resistance to antibiotics about 66%. The results of the study showed that the resistance of bacterial isolates to antibiotics did not show significant differences between soil samples treated with treated and untreated sulfur water, except for the GB2 isolate.

Life support systems and aquatic communities in public aquariums

The Pangandaran Integrated Aquarium and Marine Research Institute (PIAMARI) was developed in Pangandaran, and is equipped with public aquarium facilities. The Main Aquarium is an oceanarium in the form of a box, with a volume of 1.238 million liters, and accommodates various marine biota. This paper aims to provide an overview of the life support system used and the aquatic communities in the Main Aquarium. An inventory of principal components and equipment, the composition of biota, plankton, and ectoparasites was conducted in the oceanarium. The Main Aquarium is supported by filtration using a sand filter, protein skimmer, and an ozone generator. Water quality is maintained using the filtration combined with partial water changes. There are nine species of fish, including sharks and rays, and two species of turtles that are kept in the oceanarium, where most of the collections are omnivores, with IUCN LC conservation status and the rest NT to CR. Seven plankton genera were identified in the oceanarium (H’:1.78 and E: 0.90). There was Cryptocaryon ectoparasite infestation on the gills and skin of Trachinotus blochii with open lesions. Fish collections show different behavior and consume the fresh and artificial feed. Apart from being an edu-tourism facility, the oceanarium can act as a place for living and ex-situ culture for endangered marine biota.

Removal of Fe and Mn from the groundwater by using zeolite with Rossellomorea sp.

Groundwater is one of the alternatives to surface water that can be used for drinking water; however, it normally exists with high iron and manganese content. In this study, a column study was conducted to observe the elimination of iron (Fe) and manganese (Mn) in the groundwater under different retention times by using zeolite immobilised with iron-oxidising bacteria (IOB). Rossellomorea sp. representing an IOB, was found from the isolation process and was further cultured in the laboratory for immobilization into the natural zeolite as replacement materials for the sand filter. When the zeolite assisted with the Rossellomorea sp. was used, the elimination of Fe and Mn were 99.34% and 88.92%, respectively, compared to the removal of Fe and Mn, which were 93.62% and 93.73%, respectively, for media without immobilization. The presence of Rossellomorea sp. enhances the Fe oxidation, resulting in high removal of Fe. The Thomas and Yoon-Nelson models were performed in both raw zeolite and zeolite with IOB. The total coliform (MPN) increased from 70.8 to 307.6 MPN/100 mL due to the Rossellomorea sp. present that promotes the growth of coliform bacteria. In conclusion, the immobilization of zeolite with IOB is a potential technique to extract the Fe and Mn in the groundwater.

The abiotic removal of organic micropollutants with iron and manganese oxides in rapid sand filters for groundwater treatment.

Rapid sand filters (RSFs) have shown potential for removing organic micropollutants (OMPs) from groundwater. However, the abiotic removal mechanisms are not well understood. In this study, we collect sand from two field RSFs that are operated in series. The sand from the primary filter abiotically removes 87.5% of salicylic acid, 81.4% of paracetamol, and 80.2% of benzotriazole, while the sand from the secondary filter only removes paracetamol (84.6%). The field collected sand is coated by a blend of iron oxides (FeOx) and manganese oxides (MnOx) combined with organic matter, phosphate, and calcium. FeOx adsorbs salicylic acid via bonding of carboxyl group with FeOx. The desorption of salicylic acid from field sand indicates that salicylic acid is not oxidized by FeOx. MnOx adsorbs paracetamol through electrostatic interactions, and further transforms it into p-benzoquinone imine through hydrolysis-oxidation. FeOx significantly adsorbs organic matter, calcium, and phosphate, which in turn influences OMP removal. Organic matter on field sand surfaces limits OMP removal by blocking sorption sites on the oxides. However, calcium and phosphate on field sand support benzotriazole removal via surface complexation and hydrogen bonding. This paper provides further insight into the abiotic removal mechanisms of OMPs in field RSFs.

Pre-ozonation for gravity-driven membrane filtration: Effects of ozone dosage and application timing on membrane flux and water quality

Gravity-driven membrane (GDM) filtration has been proposed as an alternative to sand filtration for drinking water treatment, but its low membrane flux and poor permeate quality hinder its widespread application. This study investigated the effect of pre-ozonation (with various dosages and application timings) on membrane flux, fouling layer characteristics, and permeate quality during GDM filtration of river water. Pre-ozonation with 3 mg/L ozone increased the mean membrane flux by 9–54%, resulting in approximately 30% increased water production and reduced dissolved organic carbon (DOC) and extracellular polymeric substance (EPS) production by 12–35% and 9–18%, respectively. The timing of pre-ozonation significantly affected the time-dependent flux behavior and morphological characteristics of the fouling layers. Pre-ozonation from the beginning of GDM filtration enhanced the initial flux because of organic fouling control but showed a gradual flux decline with time due to EPS accumulation and biologically inactive fouling layers. Pre-ozonation from the middle of GDM filtration period created heterogeneous and porous membrane fouling layers with high biological activity, showing increased membrane fluxes and improved permeate quality by removing DOC and assimilable organic carbon (AOC) via the combined action of ozone oxidation and biodegradation/sorption in the fouling layer. Overall, our results demonstrate pre-ozonation as a potential option to overcome the limitations of GDM filtration.

Contamination of neonicotinoid insecticides in source water and their fate during drinking water treatment in the Dongguan section of the Pearl River

Neonicotinoid insecticides (NEOs) as well as their metabolites are highly mobile on the subsurface and can potentially contaminate drinking water sources; however, their pollution status and fate in the drinking water system remains ambiguous. In this study, six parent NEOs and two characteristic metabolites were measured in drinking water source protection area (source water, n = 52) and two related drinking water treatment plants (DWTPs) (n = 88) located in the Dongguan section of the Pearl River. The ubiquitous of NEOs was observed in source water with the mean concentration of total NEOs (ΣNEOs) at 240 ng/L. Although advanced DWTP (A-DWTP; range: 26 % to 100 %) showed better removals of ΣNEOs and all individual NEOs rather than those in conventional DWTP (C-DWTP; range: −53 % to 28 %), the removals were still low for acetamiprid (ACE, 26 %), thiacloprid (THD, 59 %), thiamethoxam (THM, 56 %) and N-desmethyl-acetamiprid (N-dm-ACE, 45 %) in A-DWTP. Removal rates were positive in chlorination (48 %), final stage of sedimentation (F-Sed, 24 %), and granular activated carbon (GAC) filter effluent (19 %) in A-DWTP. It worthy to note that ΣNEOs has high negative removal rates at the start stage of sedimentation (S-Sed, −83 %), middle stage of sedimentation (M-Sed, −47 %), and sand filter effluent (−42 %) water in C-DWTP, which resulted in negative removals of ΣNEOs (−9.6 %), imidacloprid (IMI, −22 %), clothianidin (CLO, −37 %), flupyradifurone (FLU, −76 %), and N-dm-ACE (−29 %) in C-DWTP. Residual levels of NEOs were high in source water, and their low or negative removals in DWTPs should be highly concerning. Results would fill the existing knowledge gap of NEOs in aquatic environment and provide a scientific dataset for policy-making on pollution control and environmental protection.

Efektifitas penyaringan Air Bersih Terhadap Kuliatas Air Sumur Gali di Kelurahan Patingalloang, Kecamatan Ujung Tanah, Kota Makassar Program Corporate Social Responsibility PT Pertamina Patra Niaga IT Makassar Tahun 2023

Introduction: site requirements for the construction of a dug well, this is necessary so that the quality of dug well water is safe in accordance with the established rules, Pollution caused by bacteria to water in the ground widens to ± 2 meters at a distance of 5 meters from the source of pollution 3 and narrows to a distance of 11 meters in the direction of the soil flow, before there was a CSR Program PT Pertamina Patra Niaga IT Makassar water quality of Dug Wells in Pattingalloang Village is very risky for environment-based diseases so it is necessary to hold clean water filtration.
 Research Method: This type of research is descriptive research, namely to determine the use of silica sand filter media – activated carbon in filter reactors to reduce TDS, Nitrite (NO2), Dissolved Manganese and MPN Coliform with a comparison of the composition of filter media with references to clean water quality standards Permenkes No. 2 of 2023, The sample in this study is 1 dug well located in Pattingaloang Village, Ujung Tanah District, Makaasar City in 2023.
 Results: this study after the filtration intervention of manganese media, activated charcoal, and silica sand CSR Program of PT Pertamina Patra Niaga IT Makassar water quality of Wells, The results of this study after filtration interventions of manganese media, activated carbon, and silica sand found that TDS, color, Manganese Nitrite (NO3) has decreased environmental pollution levels in accordance with the Regulation of the Minister of Health of the Republic of Indonesia Number 2 of 2023.
 Conclusion: The conclusion of the research results is that silica, manganese and activated carbon sand filtration media, TDS, manganese (NO2) nitrate and MPN Coliform can effectively reduce water pollution levels in dug wells in accordance with Minister of Health Regulation No. 2 of 2023. So that the risk of infectious and non-communicable diseases can be overcome by the intervention of filtration media filtration of silica sand, manganese and activated carbon.

RATIONALE FOR SELECTING SAND FILTERS FOR PRODUCTION WELLS

Link for citation: Khabibullin M.Ya., Khabibullin A.M. Rationale for selecting sand filters for production wells. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 26-34. In Rus. The relevance of the study are caused by the need to ensure the flow of more purified reservoir fluid into the bottomhole zone of the well. When opening a formation with production wells, the design of which includes anti-sand filters, there are some imperfections that are characterized by the degree and nature of its opening and are caused by the designs of casing filters. For a rational choice of an anti-sand filter in a well, it is necessary to conduct experimental bench studies, taking into account well conditions. Purpose: based on the results of experimental studies, propose the optimal design of the anti-sand filter. To select, it is necessary to take into account the hydraulic parameters of its operation, which can be determined based on the bench tests of two types of filter elements: block and frame-rod with wire winding, in open and cased hole conditions, as the most promising in terms of application. Objects. To accomplish this task, a stand was created that allows you to: determine the amount of fluid passing through with sand; the volume and granulometric state of the sands that pass through the filters when filtering the mixed liquid; state and change in the structure of rocks in the bottomhole zone of the well; distances between the filter elements and the production casing, the performance of the sand filter. The main component of the stand is a combined-shaped filtration tray imitating a circular reservoir model. Methods. The working fluid (oil), preheated to a predetermined temperature with the help of a heating element, is supplied to the filtration tray by a pump from the receiving tank through the pressure manifold. The temperature of the working fluid in a given mode is maintained using a non-contact controller. The discharge pressure is measured with a manometer. The pressure manifold is fitted with a spring-loaded relief valve. The change in pressure of the radial flow of the working fluid in the filtration tray is recorded by a pressure sensor. The working fluid from the filtration tray is passed through a cleaning system made in the form of two cylinders, in which there are sieves for trapping and screening sand particles with a size of 0,005 mm or more. The purified working fluid again enters the receiving tank. Results. Block and single-layer wire filters while ensuring a small amount of sand are quickly clogged. The double layer wire filter has the highest peak resistances and occasional significant sand production. Obviously, it can be recommended for flowing oil production, with a significant excess of reservoir pressure in relation to hydrostatic pressure.

Footprints of total coliforms, faecal coliforms and E. coli in a wastewater treatment plant and the probabilistic assessment and reduction of E. coli infection risks

Wastewater contains various pathogenic microorganisms, and the disease of workers caused by exposure to wastewater at the wastewater treatment plants (WWTPs) is a growing concern. The footprints of total coliforms (TC), faecal coliforms (FC) and Escherichia coli (E. coli) in a conventional activated sludge WWTP during 12 consecutive months were clarified. It was found that TC, FC and E.coli in influent were significantly removed (log 4.71, log 4.43 and log 4.62, respectively) by WWTP with sand filtration playing a key role, and excess sludge was a major potential pathway for them flowing to the environment. Through quantitative microbial risk assessment (QMRA), hand-to-mouth ingestion of untreated wastewater and wastewater in secondary/efficient sedimentation tanks, as well as accidental ingestion of sludge in dewatering workshop presented the highest infection risks of pathogenic E.coli in the WWTP, considerably exceeded the U.S. EPA benchmark (≤1 × 10−4 pppy). PPE application and E.coli concentration reduction in wastewater or sludge were recommended to reduce the infection risks at these stages. Further, partial ozonation and dissolved ozone flotation thickening were investigated able to reduce the infection risks at the stages of secondary and tertiary treatment of wastewater or sludge treatment by 90– 98 %. The findings of this study would assist in selecting appropriate processes for the further sanitation of WWTPs.

Performance of a gross pollutant trap-biofilter and sand filter treatment train for the removal of organic micropollutants from highway stormwater (field study)

This field study assessed the occurrence, event mean concentrations (EMCs), and removal of selected organic micro-pollutants (OMPs), namely, polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons (PHCs), nonylphenol (NP), 4-t-octylphenol (OP), and bisphenol A (BPA), in a gross pollutant trap (GPT)-biofilter/sand filter stormwater treatment train in Sundsvall, Sweden. The effects of design features of each treatment unit, including pre-sedimentation (GPT), sand filter medium, vegetation, and chalk amendment, were investigated by comparing the units' removal performances. Overall, the treatment train removed most OMPs from highway runoff effectively. The results showed that although the sand filter provided moderate (<50 % for phenolic substances) to high (50–80 % for PAHs and PHCs) removal of OMPs, adding a vegetated soil layer on top of the sand filter considerably improved the removal performance (by at least 30 %), especially for BPA, OP, and suspended solids. Moreover, GTP did not contribute to the treatment significantly. Uncertainties in the removal efficiencies of PAHs and PHCs by the filter cells increased substantially when the ratio of the influent concentration to the limit of quantification decreased. Thus, accounting for such uncertainties due to the low OMP concentrations should be considered when evaluating the removal performance of biofilters.

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.

Effects of adsorption and filtration processes on greywater microbiological contamination and the potential human health risk reduction

Abstract Recycling treated greywater (GW) for onsite, non-potable applications can reduce the potable water demand typically used for non-potable purposes. The conventional methods for GW treatment are limited in their ability to remove wide-ranging pollutants in ways that are inexpensive and use low energy. For this reason, effective and low-cost onsite treatment options are in demand. This study examines the effectiveness of sand filtration (SF), granulated blast furnace slag (GBFS), and activated carbon (AC) in the treatment of GW from a residential apartment building in Sharjah, United Arab Emirates. The study relies on four different pilot-scale experimental setups to investigate the effectiveness of SF, AC, and GBFS in treating microorganisms from GW and evaluate the microbial risk reduction using these treatment processes. A quantitative microbial risk assessment (QMRA) approach is used for risk assessment. Results show that GBFS achieves a higher reduction of total coliform (TC) (0.54–2.05 log removal) and fecal coliform (FC) (1.96–2.30 log removal) than AC. SF improves reduction by 0.13–3.39 log removal and 1.11–3.68 log removal for TC and FC, respectively. The study also reveals substantial FC and Escherichia coli risk reduction by SF, AC and GBFS.

Biochar and zero-valent iron sand filtration simultaneously removes contaminants of emerging concern and Escherichia coli from wastewater effluent

Advanced treated municipal wastewater is an important alternative water source for agricultural irrigation. However, the possible persistence of chemical and microbiological contaminants in these waters raise potential safety concerns with regard to reusing treated wastewater for food crop irrigation. Two low-cost and environmentally-friendly filter media, biochar (BC) and zero-valent iron (ZVI), have attracted great interest in terms of treating reused water. Here, we evaluated the efficacy of BC-, nanosilver-amended biochar- (Ag-BC) and ZVI-sand filters, in reducing contaminants of emerging concern (CECs), Escherichia coli (E. coli) and total bacterial diversity from wastewater effluent. Six experiments were conducted with control quartz sand and sand columns containing BC, Ag-BC, ZVI, BC with ZVI, or Ag-BC with ZVI. After filtration, Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated more than 90% (> 1 log) removal of E. coli from wastewater samples, while BC, Ag-BC, BC with ZVI and Ag-BC with ZVI also demonstrated efficient removal of tested CECs. Lower bacterial diversity was also observed after filtration; however, differences were marginally significant. In addition, significantly (p < 0.05) higher bacterial diversity was observed in wastewater samples collected during warmer versus colder months. Leaching of silver ions occurred from Ag-BC columns; however, this was prevented through the addition of ZVI. In conclusion, our data suggest that the BC with ZVI and Ag-BC with ZVI sand filters, which demonstrated more than 99% removal of both CECs and E. coli without silver ion release, may be effective, low-cost options for decentralized treatment of reused wastewater.Graphical

The Changing Climate Is Changing Safe Drinking Water, Impacting Health: A Case in the Southwestern Coastal Region of Bangladesh (SWCRB)

This study focuses on investigating the impact of climate change on the availability of safe drinking water and human health in the Southwest Coastal Region of Bangladesh (SWCRB). Additionally, it explores local adaptation approaches aimed at addressing these challenges. The research employed a combination of qualitative and quantitative methods to gather data. Qualitative data were collected through various means such as case studies, workshops, focus group discussions (FGDs), interviews, and key informant interviews (KIIs). The study specifically collected qualitative data from 12 unions in the Shyamnagar Upazila. On the other hand, through the quantitative method, we collected respondents’ answers through a closed-ended questionnaire survey from 320 respondents from nine unions in the first phase of this study. In the next phase, we also collected data from the three most vulnerable unions of Shyamnagar Upazila, namely Poddo Pukur, Gabura, and Burigoalini, where 1579 respondents answered questions regarding safe drinking water and health conditions due to climate change. The findings of the study indicate that local communities in the region acknowledge the significant impact of sea-level rise (SLR) on freshwater sources and overall well-being, primarily due to increased salinity. Over 70% of the respondents identified gastrointestinal issues, hypertension, diarrhea, malnutrition, and skin diseases as major waterborne health risks arising from salinity and lack of access to safe water. Among the vulnerable groups, women and children were found to be particularly susceptible to waterborne diseases related to salinity. While the study highlights the presence of certain adaptation measures against health-related problems, such as community clinics and health centers at the upazila level, as well as seeking healthcare from local and paramedical doctors, it notes that these measures are insufficient. In terms of safe drinking water, communities have adopted various adaptation strategies, including pond excavation to remove saline water (partially making it potable), implementing pond sand filters, rainwater harvesting, and obtaining potable water from alternative sources. However, these efforts alone do not fully address the challenges associated with ensuring safe drinking water.

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.