Drinking Water Research Articles

Effects of biological activity and feed water characteristics on the flux stabilization of gravity-driven membrane: Perspectives from biocake structure and mass balance

Gravity-driven membrane (GDM) filtration could be operated without any cleanings, has captured increasing attentions in decentralized drinking water treatment. However, the mechanism of flux stabilization during GDM long-term filtration was not comprehensively understood. This study aimed at elucidating the mechanism of flux stabilization in GDM process from the perspective of biocake layer structure and organic mass balance. The results revealed that bacteria played the fundamental role in flux stabilization and level of GDM by both engineering a rough and heterogeneous structure of biocake layer, and also hydrolyzing the organic matters on the membrane surface to maintain the dynamic balance of total organics in biocake layer. Furthermore, protozoa & metazoa would not influence the flux stabilization of GDM, but benefited to improving the stable flux level (from 4.51 L m−2h−1 to 8.68 L m−2h−1) by engineering a more porous and permeable biocake layer through the bio-predation. Regarding non-biodegradable organics (e.g., humic substance), it could be hydrolyzed into low-molecular organics to penetrate the membrane to reduce organics accumulation in the biocake layer, and achieved the mass balance, resulting in flux stabilization (7.54 L m−2h−1). However, easily biodegradable organic (e.g., sodium acetate) would promote excessive microbial growth and EPS secretion, leading to a relatively lower stable flux of GDM system (5.75 L m−2h−1). Therefore, the flux stabilization of GDM process was determined by the biological action-based dynamic balance of both the structural properties and organic mass in the biocake layer. Overall, these findings will be beneficial to promote GDM extensive application in the complex decentralized water supply.

Deciphering the driving factors and probabilistic health risks of potentially toxic elements in arid surface water: Insights from the Tarim River Basin

Potentially toxic elements (PTEs) in surface water in arid areas pose a serious threat to environmental safety and human health within a basin. It is important to determine the factors controlling PTEs and to assess the likelihood that they will pose a risk to human health in order to support the development of environmental protection and risk management strategies. In this study, a structural equation model and Bayesian method were combined to discuss the distribution and probabilistic health risks of PTEs in surface water in arid area, and the Tarim River Basin was taken as a case study. The results show that the average concentrations of As, Co, Cu, and Ni in the surface water in the Tarim River Basin ranged from 0.04 to 2.92 μg/L, which do not exceed the international standard values. However, the maximum value of As (19.20 μg/L) exceeded both the recommended drinking water standards and the Chinese irrigation water standards. Spatially, the high As concentrations were distributed in the upper reaches of the Kashgar River, and the high Co, Cu and Ni concentrations were distributed in reservoirs and lakes on the main stream of the Tarim River. The concentrations of the PTEs in the surface water in the basin were not only affected by random anthropogenic factors such as traffic discharge, agricultural activities and mining industry, but were also directly and indirectly influenced by climatic factors. The results of the probabilistic health risk assessment showed that the 95th percentile the total hazard index for infants exceeded the allowable value of 1, and the total carcinogenic risk of PTEs exposure in four age groups was at the notable level. In this study, we conducted a comprehensive analysis of the controlling factors and health risks associated with PTEs in surface water in the Tarim River Basin, and the findings are expected to provide a scientific basis for regional water environment management and safety control.

Heavy metal (Pb, Cd and Cr) contamination and human health risk assessment of groundwater in Kuakata, southern coastal region of Bangladesh

This study investigates the quality of groundwater in Kuakata, a coastal area in southwestern Bangladesh, by analyzing the levels of lead (Pb), cadmium (Cd), and chromium (Cr) in 50 groundwater samples. The concentrations of these heavy metals were determined using atomic absorption spectrometry. The results indicated that while cadmium was not detected, significant levels of lead and chromium exceeded recommended safety thresholds. The contamination was evaluated using several indices, including the heavy metal evaluation index (HEI), heavy metal pollution index (HPI), and degree of contamination (Cd). Health risk assessments for adults and children revealed potential non-carcinogenic and carcinogenic risks, particularly from lead. This study provides essential data to guide groundwater management and improve public health in the region. The groundwater samples contain traces of additional heavy metals including lead and chromium. The lead concentration ranges from 0.0003 to 0.1049 mg/L, while chromium ranges from 0.00074 to 0.1828 mg/L. The levels of certain substances in groundwater exceeded the maximum limit set by international and local health authorities for safe drinking water. Heavy metal evaluation index (HEI), along with the degree of contamination (Cd) and heavy metal pollution index (HPI), were used to assess the pollution load. The results of HEI and HPI revealed that a significant portion of the samples in the study area, specifically 34% and 38%, were found to be strongly and seriously affected, whereas 38% samples were within the highest values (>4) of Cd. Based on the hazard index (HI) and incremental lifetime cancer risk (ICLR) values, the deep groundwater in the coastal area presents a notable health risk to the local population, particularly children. This study provides essential data that can be used as a foundation for developing effective groundwater management strategies in the coastal region, with the ultimate goal of ensuring the availability of safe drinking water.

A fully integrated wireless microfluidic immunosensing system for portable monitoring of Staphylococcus aureus

The advanced devices that function fully without the need for external accessories are regarded as a pinnacle goal in the design and construction of modern ones. Staphylococcus aureus (S. aureus), a prominent human pathogen, is responsible for causing a wide variety of infections and chronic diseases. Herein, we present the first instance of a fully integrated wireless microfluidic immunosensing system (FIWMIS) capable of conducting point-of-care S. aureus monitoring in real samples of S. aureus-spiked commercial purified drinking water and S. aureus-spiked watermelon juice. The development of the proposed FIWMIS became a reality by conquering significant engineering hurdles in seamlessly integrating a microfluidic unit for liquid sample transport without the need of an external pump, an immunosensing unit for S. aureus monitoring, and an electronic control unit for signal conversion and wireless transmission. Such full integration culminated in a FIWMIS that upholds its pump-free, wireless, and low-cost characteristics for portable monitoring of S. aureus.

Safe drinking water: to what extent shallow wells are reliable?

Safe drinking water: to what extent shallow wells are reliable?

Antimony Flux and Transport Dynamics in a Mining‐Impacted River Is Linked to Catchment Hydrodynamics and Climate Oscillations

ABSTRACTWe investigate how seasonal flow variations and a climatic regime that is dominated by the El Niño–Southern Oscillation (ENSO) influence Sb flux dynamics in an Australian river impacted by mining. Sampling (n = 496) spans a hydrologically complex 7‐year period of drought, bushfires and floods from 2016 to 2023, during which 17% of samples exceeded the Sb drinking water guideline concentration (3 μg L−1). Aqueous Sb (SbAq) concentration–discharge (C–Q) relationships are non‐continuous/non‐linear across the flow range, with chemodynamic behaviour at moderate flows reflecting hydrological connection to the primary Sb‐source area combined with variable dilution. In contrast chemostatic behaviour occurred at extreme low and high flows, reflecting hydrological disconnection from the source area and persistent dilution, respectively. SbAq was significantly positively correlated (p < 0.01, Spearman's ρ = 0.58) with a Q index representing the proportional contribution of sub‐catchment flow from the mineral‐field area, suggesting sufficient localised rainfall in the Sb mining‐impacted sub‐catchment contributes to downstream peaks in SbAq concentrations. Aqueous and particulate Sb (SbP) annual loads (La) during the study period spanned 24–5174 and 1.2–2820 kg, respectively and were strongly flow dependant with extreme interannual variability reflecting dry and wet years. We extrapolate daily load‐daily discharge (Ld–Qd) relationships for SbAq and SbP to estimate Ld over a 53‐year period (1970–2023) of continuous Q data (mean total Sb La = 1865 kg ± [SE] 247). Positive correlations between the annual Southern Oscillation Index and both Sb La (p < 0.05) and proportional SbP La over 53 years suggests ENSO fluctuations influence annual Sb transport dynamics. Upstream SbP load estimates correspond with downstream estimates of coastal floodplain sedimentary Sb mass, with approximately 10%–45% of the estimated SbP exported downstream since approximately 1880 accumulated on the Macleay coastal floodplain. Data suggest at current rates of export, complete flushing‐leaching of mine tailings‐derived Sb from the upper Macleay catchment may take in the order approximately 600–1000 years.

3D reconfigurable hydroxylated carbon nanotubes-based water evaporators with long-distance transportation for continuous vapor generation

Utilizing solar-thermal power for water purification through interfacial solar steam generation represents an environmentally friendly approach to secure a clean water source. However, it is still challenging to simultaneously overcome short transport distances, low transport rates, and unsatisfactory solar-thermal energy conversion efficiency, as well as the salt accumulation problem. In this work, three-dimensional (3D) reconfigurable water evaporators are developed based on commercial fabric strings and hydroxylated carbon nanotubes. The specifically designed 3D architecture enables the fabric strings to have a long water transport distance and localized focusing of solar light that benefits the fabrication of 3D evaporators and water isolation with low heat loss. Besides, the hydroxylated carbon nanotubes with strong hydrophilicity as well as their inherent black color show high solar-heat conversion efficiency. A high evaporation rate of 3.234kg m-2h−1 is found and a solar-to-vapor efficiency of 123.21 % is also achieved by using a vertical evaporation structure due to the enlarged surface area allowing absorption of heat from the environment. Meanwhile, the accumulated salts do not block the water transport pathway and they can be easily removed in high-salinity water evaporation by employing the assembled rotating evaporator. The results suggest that the fabric rope is a good platform for exploring highly efficient evaporation structures. Combined with hydroxylated carbon nanotubes, as-designed 3D reconfigurable evaporators are promising for efficient freshwater generation.

Eco-Friendly ZnO/CuO/Ni Nanocomposites: Enhanced photocatalytic dye adsorption and hydrogen evolution for sustainable energy and water purification

Nanomaterials and nanocomposites, known for their unique properties, are increasingly vital in diverse fields such as energy and environmental remediation. This study presents biogenically synthesized ZnO/CuO/Ni nanocomposites using Mentha Pulegium L. leaf extract. The investigation focuses on their applications in photocatalytic dye adsorption and hydrogen evolution. Characterization via XRD, FTIR spectroscopy, SEM, and UV–visible spectroscopy confirms the nanocomposites’ semiconducting nature with a narrow bandgap energy of 2.46 eV. Structural analysis reveals cubic crystal structures with an average crystallite size of 29.1 nm. Under solar irradiation, the nanocomposites exhibit exceptional photocatalytic activity, degrading 99 % of 4-BP and 98 % of TB. Moreover, they achieve a notable hydrogen evolution rate of 5.79 mmol/g over six hours. These results underscore the efficacy of ZnO/CuO/Ni nanocomposites as catalysts for sustainable energy and water purification. Employing Mentha Pulegium L. extract for environmentally friendly synthesis enhances their photocatalytic properties, offering a cost-effective route to sustainable energy and clean water technologies.

A Gradient Photothermal Hydrogel with Carbon-Dots Deposited Molybdenum Disulfide Nanoflowers as Photothermal Centers for Efficient Solar-Driven Water Evaporation and Treatment

Given the urgency of water pollution and freshwater scarcity, the pursuit of efficient and clean desalination techniques has gained prominence. In this study, a multi-defective molybdenum disulfide nanoflower was synthesized within a carbon-dots solution environment, named CDs/MoS2, exhibiting exceptional photothermal and catalytic properties. Relying on the excellent photothermal properties, antibacterial rates of up to 94% and 99% against Staphylococcus aureus and Escherichia coli. Additionally, the CDs/MoS2 nanoflowers exhibited a remarkable removal efficiency of 91% for high concentrations of methylene blue (MB) through photodegradation. A gradient photothermal composite hydrogel (CDs/MoS2@PVA Hydrogel) was designed to serve as a solar-driven clean water generator to isolate drinking water from various non-potable water. The gradient hydrogel effectively enhanced solar energy absorption through light trapping, creating dispersed hot spots to capture and activate water molecules. As a result, it achieved a high evaporation rate of 1.49 kg m-2 h-1 at a solar radiation of 1 kW m-2, with an impressive solar-to-vapor conversion efficiency of 92.5%. The hydrogel was successfully employed in diverse water treatment applications, including desalination, anti-bacteria and removal of organic contaminants from water. This study presents an innovative approach to developing novel solar vapor materials for water purification purposes.

Advanced solar-driven hydrogel sponge for efficient heavy metal wastewater purification and clean water production through interfacial evaporation

Solar-driven interfacial evaporation (SDIE) technology represents a promising solution for freshwater harvesting, characterized by its cost-effectiveness, eco-friendliness, and sustainability. Nevertheless, achieving efficient removal of heavy metal ions during the SDIE process remains a significant challenge. In this study, we present a cost-effective method to construct a hybrid hydrogel evaporator by incorporating the konjac glucomannan (KGM) and reduced graphene oxide (rGO) into a polyvinyl alcohol (PVA) network. The hybrid hydrogel evaporator features a three dimensional layered structure, full spectrum absorption capability, high stability and inherent salt diffusion ability. These characteristics enabling a evaporation rate of 1.61 kg m−2 h−1 from wastewater across varying pH values (2-12) and high salinity levels (1 kW m-2). Significantly, the hybrid polymer network within the hydrogel is rich in -OH groups, enabling concurrent wipe off heavy metal ions and organic dyes from wastewater. The results in a ten thousand times reduction in the concentration of heavy metals such as Cr3+, Mn2+, Cu2+, Zn2+, and Pb2+ in the wastewater. This study provides new insights into solar evaporation technology and contributes to addressing challenges related to water scarcity.

Sustainable solar-powered seawater desalination enabled by phosphorene-decorated watermelon-like phase-change microcapsules

Solar-powered interfacial evaporation is considered as an emerging innovative technology for seawater desalination; however, it suffers from insufficient evaporation efficiency under intermittent solar irradiation. Aiming at realizing sustainable solar-powered seawater desalination for clean water production, we have designed a new type of watermelon-like phase-change microcapsules as a photothermal absorbent material for a solar interfacial evaporator. This type of phase-change microcapsules was prepared through rational layer-by-layer microencapsulation with a ZrO2 nanoparticle-containing n-docosane core as a phase-change material (PCM) for solar photothermal harvest and prompt thermal response, a ZrO2 shell for the leakage prevention of the molten n-docosane core, and a polydopamine coating layer together with its surface-decorated phosphorene nanoflakes for high-efficient sunlight absorption and fast water transportation. The resultant microcapsules are featured by a watermelon-like microstructure as confirmed by transmission electron and scanning electron microscopy. They also exhibit a high light absorption efficiency of 84.95 %, a high latent heat capacity of 146.2 J g−1, and good wettability. Equipped with the watermelon-like phase-change microcapsules, the developed solar interfacial evaporator obtained an evaporation rate of 3.09 kg m−2 h−1 under one-sun illumination for seawater desalination. The PCM core within the microcapsules can store solar photothermal energy as latent heat under sufficient solar irradiation and then release it under evaporation conditions without sunlight illumination, thus enhancing the water evaporation efficiency. This enables the developed evaporator to increase its total evaporation mass by 31.5 % on a cloudy day in comparison with the conversional solar evaporator without a PCM, indicating a remarkable enhancement in the evaporation performance under intermittent solar irradiation. The developed solar interfacial evaporator exhibits great potential for application in sustainable solar-powered seawater desalination.

An innovative Solar-Power fed atmospheric water Generator: Quantity and quality Assessments

This paper presents the generation of an alternative source of clean water through the Atmospheric Water Generation technique. A customised design using a thermoelectric cooler, powered by a renewable energy source, was used for this purpose. The system is powered by a 65-watt solar panel coupled with piezoelectricity generation utilising the mechanical power of pedestrians. As piezoelectricity production was diminutive, it was only used to supply energy to a low-power appliance. Several customized designs, as well as systematic orientations of the prototype, were examined under varying temperatures and humidity to optimise water production. It is found that the best system configuration can produce about 100 ml of water after 6 h of operation at 66 % average relative humidity and an ambient temperature of 31 °C. The water generation was a complete off-grid solution using solely solar power. As per the accumulated water-to-power input ratio, the proposed system has the maximum water generation capability (0.8333 ml h − 1 W − 1) amongst the contemporary systems. The drinkability of accumulated water samples was tested considering the Heterotrophic Bacterial and total Coliform counts, accompanied by a comparison between tap water and distilled water.

Fabrication and separation performances of composite membranes containing copper ferrite photocatalysts on graphene oxide nanosheets

An innovative approach thatintegrates photocatalysis, adsorption, and membrane separation processes was presented to degrade pollutants simultaneously during the filtration process. Firstly, a one-pot method was employed to prepare 3D graphene oxide/carbon quantum dot/copper ferrite (G/CFQ) photocatalysts. Then, the M−G/CFQ membrane was fabricated by intercalating 3D G/CFQ photocatalysts between 2D graphene oxide (GO) nanosheets using a negative pressure filtration technique. The time-dependent flux and MB residual rate results revealed that the M−G/CFQ membrane exhibited superior photocatalytic capabilities, particularly in alkaline environments. Furthermore, M−G/CFQ, when used without reaching adsorption saturation and under illumination, displayed outstanding long-term operational catalytic degradation capabilities. For a 5 ppm methylene blue (MB) solution at pH of 7, 10, and 12, the filtrate residue rates were only 8.63 %, 4.44 %, and 1.61 % respectively within 6 h. The versatility, stability, and exceptional properties of M−G/CFQ make it a promising candidate for large-scale water treatment applications, contributing significantly to the conservation of clean water resources and environmental sustainability.

An automated computational data pipeline to rapidly acquire, score, and rank toxicological data for ecological hazard assessment.

Biological Evaluations support Endangered Species Act (ESA) consultation with the US Fish and Wildlife Service and National Marine Fisheries Service by federal action agencies, such as the USEPA, regarding impacts of federal activities on threatened or endangered species. However, they are often time-consuming and challenging to conduct. The identification of pollutant benchmarks or guidance to protect taxa for states and tribes when USEPA has not yet developed criteria recommendations is also of importance to ensure a streamlined approach to Clean Water Act program implementation. Due to substantial workloads, tight regulatory timelines, and the often-protracted length of ESA consultations, there is a need to streamline the development of biological evaluation toxicity assessments for determining the impact of chemical pollutants on ESA-listed species. Moreover, there is limited availability of species-specific toxicity data for many contaminants, further complicating the consultation process. New approach methodologies are being increasingly used in toxicology and chemical safety assessment to rapidly and cost-effectively provide data that can fill gaps in hazard and/or exposure characterization. Here, we present the development of an automated computational pipeline-RASRTox (Rapidly Acquire, Score, and Rank Toxicological data)-to rapidly extract and categorize ecological toxicity benchmark values from curated data sources (ECOTOX, ToxCast) and well-established quantitative structure-activity relationships (TEST, ECOSAR). As a proof of concept, points-of-departure (PODs) generated in RASRTox for 13 chemicals were compared against benchmark values derived using traditional methods-toxicity reference values (TRVs) and water quality criteria (WQC). The RASRTox PODs were generally within an order of magnitude of corresponding TRVs, though less concordant compared with WQC. The greatest utility of RASRTox, however, lies in its ability to quickly and systematically identify critical studies that may serve as a basis for screening value derivation by toxicologists as part of an ecological hazard assessment. As such, the strategy described in this case study can potentially be adapted for other risk assessment contexts and stakeholder needs. Integr Environ Assess Manag 2024;20:2203-2217. © 2024 Society of Environmental Toxicology & Chemistry (SETAC). This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Prioritizing conservation sites for multi-pond systems to maintain protection of water quality in a fragmented agricultural catchment

Precise targeting of conservation practices to the most effective sites in multi-pond systems (MPS) is critical for resource optimization and water quality improvement. Previous studies generally prioritized ponds for conservation practices considering nutrient removal efficiency. However, they have frequently overlooked the role of ponds in sediment interception and the impact of human activities and environmental factors around the pond. Herein, the present study developed and applied a novel framework for pond prioritization by integrating the Pressure-State-Response (PSR) model, graph theory, and K-mean clustering. The framework consists of three components. An indicator system is developed to represent the nutrient removal performance of any MPS, impacts on catchment sediment connectivity, external threats, and human-initiated conservation. A flow path network considering natural and artificial elements was constructed to calculate indicator values. A cluster analysis was conducted on the index values of different ponds, and a hierarchical sorting method were used to prioritize ponds. The framework was applied to the Guilinqiao Catchment, a typical fragmented agricultural catchment in the Yangtze River Basin, China. The study has quantified the Pressure, State, and Response indices of different ponds in this catchment, prioritized the ponds, and drawn recommendations for conserving MPSs based on field surveys and remote sensing data. Ponds with higher Pressure index, higher State index, and lower Response index scores should be targeted as conservation priorities. This framework provides an effective method for ensuring management of MPSs to sustainably maximize water cleanup capacity with limited resources.

Predicting straw drinking ability of liquid foods by pipe-flow rheometry

Designing the straw drinking experience is increasingly important in consumer-oriented liquid food innovation. The perceived ’straw drinking ease’ of liquid foods could be assessed by sensory analysis. However, challenges arise in linking instrumental measurements to the subjective quantification of sensory attributes due to the complexity of perceptual behaviors in drinking. Here, we developed a pipe-flow rheometry approach to predict straw drinking ability with minimized reliance on panel tests. We measured the instantaneous flow of liquid samples within straws and compared their flow profiles based on different yielding behaviors. The dynamic flow processes were simplified into steady-state pipe flow, and perceived straw drinking ability was modeled as the shear viscosity of liquid foods at specific flow rates. A power-law relationship was found between viscosity at sample-specific shear rates and straw drinking ability, regardless of whether the liquid foods exhibit yield stress. This approach provides opportunities for directly addressing the straw drinking experience through simple laboratory measurements when developing texture modulation systems for liquid foods.

Correlation between lithium concentrations in drinking water and suicide attempt in the southeast of Iran.

Suicide, as an avoidable cause of death in public health systems, currently lacks effective global strategies to prevent it. However, several epidemiological studies found a correlation between the concentration of lithium (Li) in drinking water and lower suicide rates in the general population. Our ecologicalstudy investigated this hypothesis in the Rafsanjan districtof Iran. Samples from the public water supply in 16 areas in the district were analyzed using the graphite furnace atomic absorption. The resulting data were examined in relation to the suicide attempt from March 2019 to March 2020 obtained from Iran's Ministry of Health's registration system. During that period, 239 suicide attempts were recorded, resulting in an average of 69 individuals (85 women and 54 men) per 100,000 residents of the area. The average Li concentration in the drinking water was 47.30 µg/L (ranging from 9.4 to 141 µg/L). A negative significantcorrelation (r = -0.551, p = 0.027) between Li concentration in water and the rate of suicide attempt were observed in the studied population. Notably, these findings indicate an inverse significantrelationship between Li levels and suicide attempt rate in women (r = -0.725, p = 0.001). This is the first study in Iran that examines the relationship between Li levels in drinking water and suicide attempt rate. The findings of this study support an inverse relationship between the level of Li in public drinking water and the rate of womensuicide attempt.

Inisiasi Pengolahan Air Embung dengan Teknologi Multimedia Filter (MMF) sebagai Solusi Air Bersih di Kabupaten Bojonegoro

Clean water and proper sanitation are fundamental human needs. Nganti Village, located in Ngraho Subdistrict, Bojonegoro Regency, faces significant drought and clean water shortages, particularly during the dry season. The water quality remains subpar despite the presence of springs and water reservoirs. Consequently, processing raw water from the village's reservoir can offer a viable solution. This service activity aims to harness water reservoirs as a clean water source through multimedia filter (MMF) technology. The activities, conducted from 2022 to the end of 2023, encompass four stages: socializing the program plans, constructing multimedia filters (MMF), installing the water treatment unit on-site, and evaluating water quality, followed by necessary follow-ups. The primary activities involve installing water treatment units with MMF technology in collaboration with village officials and the community. The treated water is then tested for quality at the IPB University laboratory. Test results indicate that MMF technology significantly improves water quality, reducing parameters such as Magnesium, Manganese, Calcium, Iron, and Phosphate by 25.8‒97.8%, thus meeting quality standards. However, some parameters, such as TSS, COD, and Zinc, still exceed quality standards, necessitating further processing. This advanced water treatment requires involvement from the local government, particularly in funding through community empowerment programs, to install advanced treatment units and provide operational support for these units.

Reducing E. coli and Coliform in clean water using chlorine diffuser combined with white sand

Background: Water intended for hygiene, sanitation, and drinking must be free of physical, chemical, and microbiological pollutants. The most frequent microbiological contaminants in water are E. coli and Coliform bacteria. Chlorination, which uses chlorine compounds, is a widely used technique to eliminate germs from water. This process is regarded as effective and safe for sanitation, disinfection, and consumption. Purpose: To analyze differences in the reduction of E. coli and Coliform bacteria in water using the chlorine diffuser method combined with white sand. Method: A quasi-experimental method and a pretest posttest design, carried out at a boarding house x in Gonilan Kartasura village. The research sample was taken by purposive sampling. The sample criteria are water at the research location, namely Gonilan village which classified as densely populated. Research data was collected using observation techniques using observation sheets with three folds and three divisions of time span, namely 30 minutes, 45 minutes and 60 minutes. The data collected was then analyzed using the anova method to determine the average differences in group samples. Results: The application of a chlorine diffuser combined with white sand can reduce levels of E. coli bacteria. In the Anova test, the p-value scores were obtained at 0.045 and 0.031, thus the alternative hypothesis was accepted, namely that there was a decrease in E. coli and Coliform bacteria using the chlorine diffuser method combined with white sand. The research results in the 60th minute of the experiment went from 1 to 0. Meanwhile, there was no significant decrease in Coliform bacteria. Initially the Coliform level was 68.3, then after 60 minutes of experimentation it only decreased to 63.6. Conclusion: Based on the research carried out, it was concluded that there was a significant reduction in the levels of E. coli and Coliform bacteria using the chlorine diffuser combined with white sand with a higher dose of chlorine used.

Waste refractory brick material added chitosan/oxidized pullulan complex gel production and removal of heavy metals from waste water

Wastewater is a by-product of numerous industrial processes that have been demonstrated to have adverse effects on human and natural health due to the pollutants it contains. The pollutants in these substances are organic or inorganic molecules and heavy metal ions that significantly harm the environment and human health. A variety of techniques have been devised for the removal of heavy metal ions from wastewater. The adsorption process has attracted significant attention due to its straightforward implementation, cost-effectiveness, and the environmentally friendly production of adsorbent materials using biocompatible substances. In this study, the removal of Cu2+ ions from wastewater was conducted using chitosan pullulan, a biocompatible and biodegradable polymer. In addition to chitosan and pullulan, waste refractory materials from a furnace used in iron and steel production were added to these polymer materials to increase the adsorption capacity. The initial step involved grinding the waste refractory brick material. Subsequently, chitosan was dissolved in acetic acid. After that, the refractory material was suspended in this solution, facilitating the formation of hydrogel beads using a NaOH solution. The obtained hydrogels were coated with pullulan to produce polyelectrolyte gel. Pullulan was oxidized to 6-carboxypullulan by the TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation method and the negatively charged groups in its structure interacted with the positively charged groups in the chitosan structure to produce a complex gel. The chemical structure, morphological analysis, thermal analysis, and water release analysis of the produced waste refractory brick material added chitosan/oxidized pullulan complex gels were examined. The impact of the 6-carboxypullulan coating on the gels’ properties was elucidated. Furthermore, the adsorption of Cu2⁺ was conducted using solutions containing 100, 500, and 1000 ppm Cu2⁺ ions. It has been observed that the material can clean water with over 98% efficiency, even in solutions that exceed the standards set for wastewater. The material’s efficacy in cleaning solutions with concentrations above the standard for wastewater cleaning is evidence of its high performance. Furthermore, the kinetics and isotherm of the adsorption reaction were examined. The kinetics were determined to be consistent with the Pseudo Second Order (chemical reaction controlled) and aligned with the Langmuir and Freundlich Isotherm (mixed adsorption occurred on homogeneous and heterogeneous surfaces).