Water Odor Research Articles

Regulation of freshwater filamentous green algae (Cladophora) and its impact on malodorous volatile organic sulfur compound (DMS) by biomanipulation

When improving the water quality of natural bodies such as lakes, the explosive growth of filamentous green alga Cladophora can limit the growth of submerged macrophytes and prevent the water from shifting to a clear state. During the decay of Cladophora, it can cause various water quality issues such as reduced dissolved oxygen, increased nutrient levels and water odor. Biomanipulation, involving the introduction of a suitable density of aquatic animals into the water, can reduce the biomass of filamentous algae. We hypothesized that stocking appropriate densities of aquatic animals could reduce filamentous algal biomass and at the same time reduce the concentration of odorants in the water. Our study investigated the impact of stocking swamp shrimp (Macrobrachium nipponense), rosy bitterling (Rhodeus ocellatus), and silver carp (Hypophthalmichthys molitrix) at low (30 g/m3), medium (60 g/m3) and high (120 g/m3) densities on water quality, biomass of primary producers (such as Cladophora, submerged macrophyte and algae) and malodorous volatile organic sulfur compound dimethyl sulfide (DMS) in the water, respectively. It was found that the swamp shrimp treatment groups and the rosy bitterling high-density groups effectively inhibited the growth of filamentous green algae cover, in which the rosy bitterling high-density group reduced the filamentous green algae mat coverage by 29.65 % compared with the control group. Additionally, the high-density swamp shrimp and rosy bitterling groups notably promoted the growth of submerged macrophytes (Vallisneria denseserrulata), and significantly reduced the concentration of the malodorous DMS in the water. Overall, stocking swamp shrimp and rosy bitterling can benefit the restoration of aquatic ecology and the maintenance of clear water. However, it is essential to consider potential changes in water quality resulting from excessive stocking density. Therefore, the appropriate density and proportion of stocking should be determined in conjunction with the specific scale of the aquatic ecological restoration project.

Nitrogen reducing mechanism by microporous aeration based on microbial population characteristics: water temperature factor

ABSTRACT The formation of black odour water is primarily attributed to the elevated concentration of organic pollutants, along with an excessive amount of nitrogen and phosphorus, ultimately leading to an anoxic aquatic environment. The water temperature influence mechanism on black-odorous water restoration by microporous aeration is still lacking depth study. This paper selected (15–18) ℃ (spring and autumn), (22–25) ℃ (summer), (8–11) ℃ (winter) as temperature conditions, and investigated temperature influence on nitrogen reduction. Researches showed that: (1) The removal rates of COD, NH4 +-N and TN were significantly positively correlated with temperature (r = 0.99, 0.96, 0.97), the lowest removal rates were 83.16%, 95.68%, 58.7% ((8–11) ℃), the highest values were 92.67%, 98.27%, 70.96% ((22–25) ℃), respectively. (2) At a temperature range of 22–25°C, the microbial community exhibited the highest levels of abundance, diversity, and uniformity. Notably, Proteobacteria dominated this temperature range with a relative abundance of 79.72%. Furthermore, temperature positively correlated with the majority of dominant bacterial species, suggesting that conditions at 22–25°C are highly conducive to the growth of most bacterial communities. Among these, Limnohabitans, Alsobacter, and Candidatus_Aquirestis, which possess key functions in denitrification and nitrogen removal, displayed significantly higher abundances. It explains the positive correlation between temperature and removal rates of COD, TN and NH4 +-N from microbial population’s perspective. Thus, the best temperature for repairing black-smelly water is (22–25) ℃. This study provides technical reference for mechanism research and practical application of microporous aeration.

Novel drainage pipeline breakages detection based on MEMS inertial sensor: From mechanism to application

Urban water environment pollution is a global concern, in developing countries, sewage infiltration resulting from urban drainage pipelines breakage is an essential element in the urban groundwater pollution and the recurrence of black odor water bodies, it is crucial to accurately and efficiently detection and localisation of urban drainage pipelines breakage to protect the urban water resources. In this paper, a device for detecting defects in drainage pipelines was developed and assembled using microelectromechanical systems (MEMS) inertial sensors as the core components, and the improved cumulative sum (CUSUM) model was used for anomalous detection of the pitch angle of the device's movement along the course of the pipeline as a method of detecting pipeline breakage. In the laboratory simulation of drainage pipeline tests, the CUSUM peaks (0.709, 1.102, 3.038, 7.990) for the case of external water infiltration rates into the pipeline at the point of pipe breakage (2.9%, 4.6%, 5.8%, 9.2%), and for the cases of sewer exfiltration rates in the pipeline of 4.2% and 6.4% (0.760, 1.382). CFD simulations of the water flow in the laboratory pipeline show a high degree of overlap between the trend of the water surface near the point of breakage and the anomalous fluctuations in the pitch angle of the device motion in the laboratory tests. Finally, the authors tested the device on municipal drains in the city of A. The results demonstrated the reliability and high accuracy of the device. The device enables to improve the ecological quality of urban water environment by accelerating the rate of defect detection in urban drainage pipelines and reducing the detection expenses.

Adsorption of Humic Acid from Water Using Metal-Organic Frameworks (MOFs): An Effective Removal Strategy

The escalating presence of humic acid (HA) in aquatic systems poses significant ecological and potable water treatment challenges, altering the color, taste, and odor of water and fueling algal blooms that deplete oxygen levels to the detriment of aquatic life. Traditional techniques like coagulation-flocculation, membrane filtration, oxidation fall short in efficiency due to its small fraction of HA, Humic acids (HAs) can interact with various organic and inorganic substances, affecting their characteristics and behavior in water. These interactions can influence the efficiency of water treatment processes like adsorption and coagulation. Specifically, HAs may compete with other contaminants for treatment sites or alter the chemical conditions of the treatment processes, impacting their effectiveness. This thesis confronts the pervasive issue of HA contamination by leveraging the advanced properties of metal-organic frameworks (MOFs). In this work, four representative MOFs are synthesized and well characterized. Then, their capability to enhance coagulation processes in water for HA and HA-kaolin treatment are detailed evaluated. The findings from this research extend beyond academic curiosity, offering actionable insights for water treatment facilities and environmental management agencies. The synthesis of MOFs which are UiO-66(Zr), MIL-100(Fe), ZIF-8, and Al-fum. Each MOFs have been applied to remove HA by adsorption under different condition, effect of contact time, effect of initial pH, effect of adsorbent dosage. After adsorption experiment, MOF samples prepared to dry and went through characterization. Removal of HA by MOF adsorption showed UiO-66(Zr) and MIL-100(Fe) examined shortest reaching equilibrium state with 10-15 min, however, ZIF-8 and Al-fum gradually reached equilibrium state after 60 min. Among various pH conditions, UiO-66(Zr) and MIL-100(Fe) showed the highest adsorption capacity under acidic conditions, while ZIF-8 excelled at neutral pH, and Al-fum exhibited the highest adsorption capacity under both acidic and basic conditions. ZIF-8 has the highest adsorption capacity among the MOFs with capacity of 754 mg/g. MOF after adsorption samples went through characterizations and their remained characteristics indicating the adsorption not affected the structure of the MOFs.

Predicting Odor Sensory Attributes of Unidentified Chemicals in Water Using Fragmentation Mass Spectra with Machine Learning Models.

Knowing odor sensory attributes of odorants lies at the core of odor tracking when addressing waterborne odor issues. However, experimental determination covering tens of thousands of odorants in authentic water is not pragmatic due to the complexity of odorant identification and odor evaluation. In this study, we propose the first machine learning (ML) model to predict odor perception/threshold aiming at odorants in water, which can use either molecular structure or MS2 spectra as input features. We demonstrate that model performance using MS2 spectra is nearly as good as that using unequivocal structures, both with outstanding accuracy. We particularly show the model's robustness in predicting odor sensory attributes of unidentified chemicals by using the experimentally obtained MS2 spectra from nontarget analysis on authentic water samples. Interpreting the developed models, we identify the intricate interaction of functional groups as the predominant influence factor on odor sensory attributes. We also highlight the important roles of carbon chain length, molecular weight, etc., in the inherent olfactory mechanisms. These findings streamline the odor sensory attribute prediction and are crucial advancements toward credible tracking and efficient control of off-odors in water.

From black liquor to tinted sunscreens: Washing out Kraft lignin unpleasant odor and improving its properties by lignin nanoparticle preparation

Kraft lignin is a major byproduct of pulp and paper processing, presenting outstanding properties, including antioxidant action and UV and visible light absorption. Despite being a promising low-cost and renewable ingredient for dermo-cosmetic formulations, lignin use is restricted primarily because of its unpleasant odor and poor dispersibility in water. This study presents an integrated and environmentally friendly method to eliminate lignin odor, followed by improving its dispersibility in water through lignin nanoparticle (LNP) production, and, finally, evaluating their application in cosmetic formulations to act as antioxidant and UV-blocker. Starting with black liquor, Kraft lignin was precipitated and washed with water at 70°C, effectively removing lignin odor by a straightforward method, reducing its sulfur content from 5.6 to 2.9 wt%, and the ashes to negligible values without compromising the lignin structure. LNPs were successfully produced by the self-assembly method, yielding spherical and colloidally stable particles (zeta potential ca. −30 mV) with diameters ranging between 25 and 200 nm, outperforming particles prepared by sonication and bulk lignin itself. LNPs prepared by self-assembly method showed exceptional antioxidant activity, eliminating up to 79.2 % of DPPH• radicals (52 % more than bulk lignin) and showing in vitro SPF of ca. 15 with only 0.5 wt% of particle concentration, in addition to the improved dispersibility in cosmetic formulation.

Removal of Humic Acid by UiO-66(Zr) and MIL-100(Fe) Metal-Organic Frameworks (MOFs) Adsorption

The escalating presence of humic acid (HA) in aquatic systems poses significant ecological and potable water treatment challenges, altering the color, taste, and odor of water and fueling algal blooms that deplete oxygen levels to the detriment of aquatic life. Traditional techniques like coagulation-flocculation, membrane filtration, oxidation fall short in efficiency due to its small fraction of HA. This study confronts the pervasive issue of HA contamination by leveraging the advanced properties of metal-organic frameworks (MOFs). In this work, two representative MOFs are synthesized and well characterized. Then, their capability for removal HA by adsorption process in water for HA treatment are detailed evaluated. The findings from this research extend beyond academic curiosity, offering actionable insights for water treatment facilities and environmental management agencies. The synthesis of MOFs which are UiO-66(Zr), MIL-100(Fe). Each MOFs have been applied to remove HA by adsorption under different condition. The effect of contacting time, initial pH, adsorbent dosage has been evaluated. After adsorption experiment, MOF samples prepared to dry and went through characterization. Removal of HA by MOF adsorption showed UiO-66(Zr) and MIL-100(Fe) examined rapid reaching equilibrium state with 10-15 min. Among various pH conditions, UiO-66(Zr) and MIL-100(Fe) showed the highest adsorption capacity under acidic conditions. MIL-100(Fe) achieves a higher maximum adsorption capacity than MIL-100(Fe). MOF after adsorption samples went through characterizations and their remained characteristics indicating the adsorption not affected the structure of the MOFs.

Integration of nontarget analysis with machine learning modeling for prioritization of odorous volatile organic compounds in surface water

Assessing the odor risk caused by volatile organic compounds (VOCs) in water has been a big challenge for water quality evaluation due to the abundance of odorants in water and the inherent difficulty in obtaining the corresponding odor sensory attributes. Here, a novel odor risk assessment approach has been established, incorporating nontarget screening for odorous VOC identification and machine learning (ML) modeling for odor threshold prediction. Twenty-nine odorous VOCs were identified using two-dimensional gas chromatography-time of flight mass spectrometry from four surface water sampling sites. These identified odorants primarily fell into the categories of ketones and ethers, and originated mainly from biological production. To obtain the odor threshold of these odorants, we trained an ML model for odor threshold prediction, which displayed good performance with accuracy of 79%. Further, an odor threshold-based prioritization approach was developed to rank the identified odorants. 2-Methylisoborneol and nonanal were identified as the main odorants contributing to water odor issues at the four sampling sites. This study provides an accessible method for accurate and quick determination of key odorants in source water, aiding in odor control and improved water quality management. Environmental ImplicationWater odor episodes have been persistent and significant issues worldwide, posing severe challenges to water treatment plants. Unpleasant odors in aquatic environments are predominantly caused by the occurrence of a wide range of volatile organic chemicals (VOCs). Given the vast number of newly-detected VOCs, experimental identification of the key odorants becomes difficult, making water odor issues complex to control. Herein, we propose a novel approach integrating nontarget analysis with machine learning models to accurate and quick determine the key odorants in waterbodies. We use the approach to analyze four samples with odor issues in Changsha, and prioritized the potential odorants.

Assessment of the Physico-Chemical Quality of Untreated and Treated Water Using Water Quality Index (WQI) in the Ain Zada Dam, East Algeria

The Ain Zada dam is experiencing a deficit in recent years due to scanty precipitation and reduced water flow, resulting in the dam’s water reserve dropping to 8.3%. Our study’s primary objective is to assess the quality of both untreated (raw) and treated water from the Ain Zada dam by conducting physico-chemical analyses on both samples. Based on the findings, the physico-chemical quality of the treated water is deemed satisfactory, as all samples adhere to Algerian standards. The treated water exhibits an organic matter concentration of 4.94 mg/l, which is the chief contributor to the unfavourable odour and taste of the dam water. To address this, enhancements will be made to the Ain Zada dam treatment station this year through the adoption of a novel ozone disinfection method (ozonation). The Water Quality Index (WQI) for treated water from the Ain Zada dam indicates a favourable suitability for drinking water production from February to May 2022. Two quality categories are discernible for each scenario based on the obtained WQI values: excellent and good for treated water, and excellent and poor for raw water. Water quality diminishes notably in April, where the treated water quality index rises (25 < WQI . 50), while the raw water’s quality classifies as poor (WQI > 50). The decline in water quality during this month can be attributed to stream variations, agricultural activities, and urban wastewater discharges. Consequently, it is imperative to prioritise the reduction of these pollution sources to safeguard water resources and enhance water quality within the watershed.

Production and release of 2-MIB in Pseudanabaena: Effects of growth phases on cell characteristics and 2-MIB yield

2-methylisoborneol (2-MIB), a secondary metabolite produced by cyanobacteria, often causes a musty odour in water, threatening the safety of drinking water supplies. This study investigated the effects of the growth phases on the production of 2-MIB by Pseudanabaena. The effects of cell characteristics on the production and release of 2-MIB were also explored. The total 2-MIB concentration increased during the exponential phase and decreased during the declining phase, which was consistent with the changes in cell density. However, the total 2-MIB yield (1.12–1.27 fg cell−1) of Pseudanabaena did not significantly differ throughout the growth cycle (p > 0.05). Meanwhile, the extracellular 2-MIB yield increased significantly from 0.31 fg cell−1 in the exponential phase to 0.76 fg cell−1 in the declining phase (p < 0.05), and the corresponding proportion of extracellular 2-MIB improved from 25.13% to 59.16% (p < 0.05). The surge in extracellular 2-MIB during the declining phase could be attributed to the breaking of the Pseudanabaena filament, as indicated by the decrease in Dmean during cell ageing. The findings of this study contribute to a more inclusive comprehension and management of musty odour issues resulting from cyanobacteria in the water supply.

Comparison of four pre-oxidants coupled powdered activated carbon adsorption for odor compounds and algae removal: Kinetics, process optimization, and formation of disinfection byproducts

Pre-oxidation and powdered activate carbon (PAC) are usually used to remove algae and odorants in drinking waterworks. However, the influence of interaction between oxidants and PAC on the treatment performance are scarcely known. This study systematically investigated the combination schemes of four oxidants (KMnO4, NaClO, ClO2, and O3) and PAC on the inactivation of Microcystis aeruginosa cells and removal of four frequently detected odorants in raw water (diethyl disulfide (DEDS), 2,2′-oxybis(1chloropropane) (DCIP), 2-methylisoborneol (2-MIB) and geosmin (GSM)). O3 showed highest pseudo-first-order removal rate for all four compounds and NaClO exhibited highest inactivation rates for the cell viability and Chlorophyll a (Chl-a). The Freundlich model fitted well for the adsorption of DEDS and DCIP by PAC. When treated by combined oxidation/PAC, the removal ratio of algae cells and odorants were lower (at least 1.6 times) than the sum of removal ratios obtained in oxidation or PAC adsorption alone. Among these four oxidants, the highest synchronous control efficiency of odorants (52 %) and algae (66 %) was achieved by NaClO/PAC. Prolonging the dosage time interval promoted the removal rates. The pre-PAC/post-oxidation processes possessed comparable efficiency for the removal of odorants and algae cells comparing with pre-oxidation/post-PAC process, but significantly inhibited formation of disinfection byproducts (DBPs), especially for the formation of C-DBPs (for NaClO and ClO2), bromate (for O3) and chlorate/chlorite (for ClO2). This study could provide a better understanding of improving in-situ operation of the combined pre-treatments of oxidation and PAC for source water.

Morphological Analysis of the Olfactory System of the Pig-Nosed Turtle, Carettochelys insculpta.

The turtle olfactory organ consists of the upper (UCE) and lower (LCE) chamber epithelium, projecting to the ventral and dorsal parts of the olfactory bulbs, respectively. The UCE is associated with glands, contains ciliated olfactory receptor neurons, and is assumed to detect odorants primarily in air, while the LCE is devoid of glands, contains microvillous olfactory receptor neurons, and is assumed to detect odorants primarily in water. Examining the olfactory system of the pig-nosed turtle, Carettochelys insculpta, this study found that both the upper and lower chambers of the nasal cavity were lined with sensory epithelium devoid of associated glands and contained ciliated olfactory receptor neurons. Moreover, the olfactory bulbs were not divided into dorsal and ventral parts. These results suggest that the olfactory system of the pig-nosed turtle is a single system specialized for detecting odorants in water.

Application of chitosan-based materials in wastewater treatment

Chitosan, as a natural polysaccharide material, plays a great role in the field of wastewater treatment due to its good biodegradability, antimicrobial activity, and other properties. However, it may have some differences in the processes of adsorption, flocculation, and membrane separation. We comprehensively describe the application effect and mechanism of action of chitosan-based materials on the above three major water treatment processes. In the adsorption process, chitosan-based adsorbents such as hydrogels and chitosan beads are prepared by cross-linking, impregnation, and the introduction of functional groups. These chitosan-based materials exerted efficient removal performance in the adsorption of heavy metals, organic dyes, anionic pollutants, etc., which was attributed to their large specific surface area and abundant functional groups. In the flocculation process, the chitosan-based materials were modified by grafting and modifying their shape, while heavy metal ions, organic dyes, and algae were removed using processes such as chelation and charge neutralization. In the membrane separation process, a number of nanofiltration and microfiltration membranes were created by coating chitosan ions, and physicochemical modification was done for the separation of heavy metal ions and emulsified oil droplets in water to improve the fouling resistance and retention rate of the membrane materials. This paper reviews the application of chitosan-based materials in wastewater treatment and proposes that in-depth studies on their toxicity and reusability should be conducted in the future, with a view to playing a role in areas such as the removal of malodorous water odors.

Determination of earthy-musty odors in tap water by gas chromatography‒mass spectrometry with silica solid-phase extraction

This research aimed to develop an effective method for detecting semivolatile earthy-musty odors without using the conventional sample processing equipment used for volatile compounds. The concurrent isolation of 2-methylisoborneol (2-MIB), trans-1,10-dimethyl-trans-9-decalol (geosmin, GSM), 2-isopropyl-3-methoxy pyrazine (IPMP), and 2-isobutyl-3-methoxy pyrazine (IBMP) in tap water was successfully achieved by employing a combination of n-hexane liquid‒liquid extraction (LLE) and silica solid-phase extraction (SPE) techniques. Gas chromatography–mass spectrometry (GC-MS) was utilized for the identification of these targets, with the inclusion of borneol (BN) as an internal reference. This robust method was optimized and validated. It was found that the method showed good linearity in the range of 0.5–100 ng/mL and produced good recoveries (84.6 %–103 %) with satisfactory relative standard deviations (1.50 %–10.1 %). The determined limits of detection (LODs) for the group of four substances were found to vary from 0.3 to 0.9 ng/L, whereas the limits of quantitation (LOQs) exhibited variations between 1 and 3 ng/L. The subsequent implementation of this methodology to evaluate the four previously described off-flavor chemicals in tap water resulted in satisfactory results.

Use of recycled aggregates as filter support and filter media for decentralized water filtration systems

Clean drinking water is crucial for maintaining public health and can be considered a fundamental right of people. Unfortunately, access to potable water is limited for residents of developing and underdeveloped countries, especially in rural communities. Conventional treatment systems for such regions are challenging in terms of installation, operation, and maintenance. An emerging problem of rapid urbanization and proliferating construction industry is huge quantities of Construction and Demolition (C & D) waste, which needs proper reuse and/or disposal. A simultaneous solution to these twin problems is the formulation of a decentralized water filtration system using C & D waste aggregates. In the current study, small-scale (5-lt capacity), decentralized water filtration systems were designed and tested for the treatment of surface water samples. Fresh aggregates were replaced by C & D waste aggregates progressively in the drainage media, support media, and filter media; resulting in a total of seven test filtration devices. The effectiveness of such filters was evaluated for treating river water samples. It was found that the filters prepared with C & D waste aggregates were successful in the removal of turbidity, total solids, and total dissolved solids (TDS). Removal efficiencies up to 98% for turbidity, 86% for total solids, and 61% for the TDS were observed for different combinations of fresh and recycled aggregates in these filters. The results also show that filters made with only recycled aggregates can also yield high levels of contaminant removal and cleaner water. Further, the color and odor of the raw water were also significantly improved. These results show that C & D waste can be successfully incorporated into decentralized water treatment systems and can result in high-quality water through low-cost and low-tech, easy-to-maintain/operate devices.

Action Mechanism of Bacillus on Microalgae During Nitrogen Metabolism in Urban Tailwater

To improve deep denitrification of black and odorous water and improve the quality of surface water, we studied the characteristics of nitrogen metabolism and denitrification of urban tailwater by microalgae (Z), Bacillus (Y), and Bacillus microalgae (ZY). The results showed that there was a good removal effect of ammonia nitrogen of group Z and group ZY in urban tailwater. The degradation rate of both groups reached 95%. The best effect on the removal of nitrite nitrogen was of group Z in urban tailwater. The combined action of Bacillus and Micrococcus played a relatively strong and stable effect on the conversion of nitrite nitrogen to nitrate nitrogen in the nitrogen cycle reaction. Bacillus could effectively remove nitrate nitrogen and improve the removal efficiency of nitrate nitrogen by microalgae. Best removal effect of nitrate nitrogen was observed in group ZY in urban tailwater, with a degradation rate as high as 99%, in which the nitrate nitrogen was removed almost completely. The Bacteria with high proportions in Z were Chroococcidiopsis_PCC_7203 (24.38%), uncultured_bacterium-g_norank_f_A4b (23.65%), Exiguobacteriu (7.09%), Leptolyngbya_PCC-6306(9.41%), and Bacillus (1.99%). The bacteria with high proportions in ZY were Brevibacillus (22.94%), Clostridium (8.78%), and Bacillus (4.88%), and the proportion of Chroococcidiopsis_PCC_7203 was only 7.84% in ZY, which was considerably lower than that in Z samples. The conclusions were as follows:microalgae could effectively remove ammonia nitrogen in the system. Bacillus and microalgae had very good removal effect of ammonia nitrogen and nitrate nitrogen. During the nitrogen removal of black and odorous water by algae, the Bacillus inhibited the excessive growth of microalgae and prevented eutrophication and black odor in water. This study can provide data support for the deep treatment of urban tail water and prevention of surface water eutrophication.

Quality evaluation and storage test for capsaicin-fortified yogurt based on the multilayer nanoemulsion system.

Capsaicin has many benefits, such as pain relief, cancer prevention, and weight reduction. However, the application of capsaicin has been limited in the food industry due to its strong pungency, odor, and low solubility in water. Therefore, a multilayer nanoemulsion with chitosan and hyaluronic acid was developed for masking its odor and taste and improving the physicochemical stability against the surrounding environment. The capsaicin-fortified yogurts were prepared by blending various concentration levels of multilayer nanoemulsion (0-15%, w/v). The quality of yogurt was determined as a function of pH, acidity, viscosity, and total lactic acid bacteria population in an extended storage period (21days). The multivariate statistical analysis was used to compare the quality of yogurts supplemented with capsaicin nanoemulsion. As a result, this study demonstrated the potential of capsaicin-loaded multilayer emulsion-supplemented yogurt as a novel nutrition-fortified food.

Water Quality Status of Way Batanghari River, Metro City, Lampung Province Based on Water Fit for Consumption Parameters

Introduction: The need of water fit for consumption will continue to be sustainable along with the increasing human population, so we need a source of clean water that suitable for consumption. Therefore, this study aims to determine the water quality status of the Way Batanghari river based on an analysis of the feasibility of potable water. Methods: This research used survey method and water sampling in the Way Batanghari tributary, Metro City, Lampung using the consecutive sampling method. Results and Discussion: The physical parameters which include water color exceeds the 50 TCU and indicates the odor of ammonia. The chemical parameters which include COD were 63.5 mg/L (4th class) upstream, 59.3 mg/L (4th class) downstream. DO values upstream were 4.36 mg/L (1st class), 2.83 mg/L (3rd class) downstream. The phosporus value shows a number of 0.54 mg/L (2nd class). pH parameter which shows a value of 7.1 on the upstream, 6.6 on the downstream. Found species from class of Bacillariophyceae, Cyanophyceae as parameters of pollution. Conclusion: Based on Regulation of the Minister of Health, Republic of Indonesia Number 492 of 2010, this river has color and odor of water shows that indicates not meet the requirements for consumption.

Possibility for detecting 14 typical odorants occurring in drinking water by employing human odor-binding protein OBP2a

Odor issues occurring in drinking water have been a big challenge to face for water suppliers globally, which highly commend to develop quick or on-site odor detection tools for the management of odor problems. Olfactory sensors based on odor-binding proteins (OBPs) have been utilized to analyze pollutants in food and air samples, while their application for the detection of typical odor-causing compounds in drinking water is rarely reported, partly due to the lack of knowledge about the binding properties of odorants. In this study, the binding affinity and mechanism of human odor-binding protein OBP2a to 14 typical odorants in water were first assessed using fluorescent competitive binding assays and molecular docking techniques. The 14 odorants include 7 aldehydes, 2 terpenes, 2 thioethers, bis(2-chloro-1-methylethyl) ether (DCIP), 2-ethyl-4-methyl-1,3-dioxolane (2E4MDL), and 2-isobutyl-3-methoxypyrazine (IBMP). The results showed that OBP2a could bind to 9 odorants (Ki = 29.91 μmol/L–48.36 μmol/L), including IBMP, 2-MIB, and six aldehydes (hexanal, heptanal, benzaldehyde, 2-octenal, decanal, and β-cyclocitral), among which stronger binding affinity for aldehydes is observed (Ki = 29.91 μmol/L–43.87 μmol/L). Molecular docking confirmed that Lys112 and Phe97 are major amino acid residues involved in the binding of the most target odorants. To be specific, IBMP and aldehydes can form hydrogen bonds with Lys112; aromatic ring-containing odorants such as IBMP and benzaldehyde can also form pi–pi stacking with Phe97. The binding affinity of OBP2a to fatty aldehydes including hexanal, heptanal, 2-octenal, decanal, and β-cyclocitral increased with the increase of hydrophobicity of aldehydes. The valuable information to the binding of OBP2a to typical odorants in this study would provide a theoretical foundation for the development of OBP-based odor detection biosensors to achieve quick detection in drinking water, further helping the improvement of water treatment processes in the water industry.Graphical

The optimal method for water quality parameters retrieval of urban river based on machine learning algorithms using remote sensing images

ABSTRACT Water eutrophication has become one of the prominent problems of environmental protection in inland watersheds. Turbidity, total phosphorus (TP) and total nitrogen (TN) concentrations are key water quality parameters (WQPs) that reflect the level of water eutrophication in inland waters. Due to the complex interaction effects between different water quality in urban rivers, the water quality retrieval models still have the problem of single input features and poor applicability. This paper proposed a robust feature selection method based on machine learning and utilized Sentinel-2 remote sensing images for water quality retrieval of Chan and Ba rivers in Xi’an City. The ReliefF and global sensitivity analysis (GSA) methods (ReliefF-GSA) were used to select the optimal feature combination from the potential feature dataset. Based on the optimal feature combination, Random Forest regression (RFR), LightGBM and XGboost models were constructed for the three WQPs retrieval, respectively. The optimal models were then used to invert the three WQPs and the spatial-temporal variation of WQPs from January 2021 to January 2022 was analysed. The results show that (1) The RelieF-GSA method is suitable for high-dimensional feature filtration and enables optimal feature selection for specific WQPs retrieval. It is revealed that the BOI index (black odour water index) is the key feature for the retrieval of turbidity and TN concentration. (2) The RFR model was found to be better than other models and more appropriate for Chan and Ba rivers, with coefficients of determination (R2) of 0.90, 0.89 and 0.81, respectively. (3) It was found that the water qualities in the Chan and Ba rivers have prominent seasonal characteristics. Turbidity and TP concentrations showed higher, while TN concentration showed relatively low in autumn. The method and conclusions of this paper can further provide a reference for WPQs retrieval in urban rivers.