Oxidation-reduction Potential Research Articles

Smart measurement and monitoring system for aquaculture fisheries with IoT-based telemetry system

The instrumentation design of an online monitoring device for aquaculture media is discussed in this article. The main processor in this internet of things (IoT) real-time telemetry system is an ESP32 board. Temperature, acidity level, conductivity level, dissolved oxygen (DO) level, and degree of oxygen reduction in the water were the aquaculture parameters measured. The ESP32 collects data from each sensor, groups it into a dataset, displays it on the LCD, saves it to the SD card, and then uploads it to the real-time database. In addition, an Android application is being developed for users. This device has been tested to ensure that each measured parameter is accurate and precise. The accuracy test, one of the major results of laboratory scale tests, demonstrates that each parameter has a different measurement error that represents with average error absolute. Six tested sensors/instruments were subjected to the test. Average absolute error for temperature sensor is +0.76%, pH sensor is +1.52%, electrical conductivity (EC) sensor is +10.8%, oxidation reduction potential (ORP) sensor is +14.6%, DO sensor is +9.3%, and total dissolve solids (TDS) sensor is +13.2%. This device is very dependable and convenient for monitoring the condition of aquaculture media in real-time and accurately.

Characterization of slightly acidic electrolyzed water on effective disinfection against microbial safety and retention of phenolic compound in SAEW treated fresh romaine lettuce

Abstract This study investigated the effects of processing parameters, specifically the low rate and the combination of diluted HCl and salt (NaCl) at different concentrations, on the properties of the slightly acidic electrolyzed water (SAEW) that was produced. The properties of the SAEW that were analyzed included pH, oxidation-reduction potential (ORP), available chlorine concentrations (ACC), and generated hypochlorous acid (HClO) concentration. NaCl alone resulted in the lowest pH (<4) and the highest ORP values (>1000 mV). Increasing HCl concentrations significantly raised pH levels to greater than 5 and lowered ORP values of SAEW, with the highest pH (5.7) observed with 1.5% HCl and 5% NaCl. The highest HClO concentration of 19.65±1.03 mg/L was obtained with 1.5% HCl:5% NaCl. Interestingly, the concentration of NaCl showed no significant effects on the production of HClO. Furthermore, different concentrations of combined NaCl and HCl significantly influenced the inactivation efficiency on total aerobic bacteria count and changes in phenolic compound content. Increasing HCl concentrations from 0.5% to 2.0% led to an increase in the reduction of aerobic bacteria counts from 2.51 to 4.22 log CFU/g with 5% NaCl and from 2.49 to 3.52 log CFU/g with 10% NaCl. Flow rates significantly contributed to the change in HClO formation and altered the properties of the produced SAEW. Results indicated that SAEW treatment significantly reduced total aerobic bacteria counts. The lower flow rates (0.3 L/min) produced the highest log reductions. Additionally, SAEW treatment led to a reduction in phenolic content, even though considerable amount was retained at lower HClO concentrations. These findings offer valuable information on optimizing SAEW treatment protocols for enhancing microbial safety and extending the shelf life of fresh produce, while considering the impact on the content of phenolic compounds.

The Effect of Apple Vinegar Addition on the Quality and Shelf Life of Cooked Sausage during Chilling Storage

As more and more consumers are becoming conscious of the safety and taste of meat products, the use of natural additives and innovative processing techniques has gained significant attention. Naturally fermented fruit vinegar is rich in organic acids and antioxidant phenolic compounds. In addition, it contains amino acids, minerals, vitamins, and provitamin beta-carotene, and the presence of acetic acid bacteria may have a positive effect on consumer health. The study aimed to assess the impact of different concentrations of apple vinegar addition on the quality of cooked sausage, focusing on physicochemical parameters, including fatty acid profile and oxidative stability, as well as microbiological quality and sensory changes after production and during chilling storage. Four variants of sausage were prepared: C—sausage without apple vinegar; V1—sausage with 1% of apple vinegar; V3—sausage with 3% of apple vinegar; and V5—sausage with 5% of apple vinegar. All of the tests were carried out after production, as well as after 7 and 14 days of refrigeration storage. The addition of apple vinegar decreased the pH value and increased the oxidation-reduction potential and lipid oxidation in the samples V1, V3, and V5. The sausage with the 5% addition of apple vinegar (V5) was characterized by significantly more intensive brightness (parameter L* = 54.67) in comparison to the C sample (parameter L* = 52.78). The sausages that were tested showed good microbiological quality concerning the total number of microorganisms, lactic acid bacteria, and the absence of pathogenic bacteria. The addition of apple vinegar contributed to the reduction in the intensity of the cured meat flavor and the fatty flavor. Therefore, according to the results presented in this work, it can be concluded that 3% of vinegar is the optimal addition, which may be used in the next step of investigation, taking into account color formation abilities as well as microbiological quality and lipid oxidation processes.

Antimicrobial effect of plasma-activated water combined with tartaric acid against Staphylococcus aureus and its application on fresh-cut asparagus lettuce

Plasma-activated water (PAW) is increasingly recognized for its role in mitigating microbial contamination in fresh-cut produce, but its disinfection effectiveness can be limited under certain conditions. Notably, dissolving organic acids in PAW is an effective way to boost its antimicrobial properties through a synergistic effect. This study examined the enhanced antimicrobial efficacy of PAW when combined with tartaric acid against Staphylococcus aureus and its application on fresh-cut asparagus lettuce. Results demonstrated that PAW combined with tartaric acid showed stronger antimicrobial efficacy than PAW alone (p < 0.05). The addition of tartaric acid to PAW increased the oxidation-reduction potential and lowered the pH, contributing to its superior antimicrobial performance against S. aureus. The underlying antimicrobial mechanisms included the inactivation of Ca2+-Mg2+-ATPase and Na+-K+-ATPase accompanied by damage to bacterial cell membrane, enhanced oxidative damage due to the influx of extracellular reactive oxygen species such as H2O2, the disrupted energy metabolic activities, and the mitigated bacterial defense system constructed by antioxidant enzymes, such as superoxide dismutase and catalase. Furthermore, the synergistic treatment improved the quality of fresh-cut asparagus lettuce by retarding browning, curbing microbial spoilage, and lessening weight loss. The preservation of color was largely due to the decreased activities of polyphenol oxidase and peroxidase, along with controlled chlorophyll degradation. These findings suggest that PAW enhanced with tartaric acid could be a promising, cost-effective disinfection strategy for fresh-cut asparagus lettuce.

Influence of oxidation reduction potential and pH on polysulfide concentrations and chain lengths in the biological desulfurization process under haloalkaline conditions

Biological desulfurization under haloalkaline conditions has been applied worldwide to remove hydrogen sulfide (H2S) from sour gas steams. The process relies on sulfide-oxidizing bacteria (SOB) to oxidize H2S to elemental sulfur (S8), which can then be recovered and reused. Recently, a dual-reactor biological desulfurization system was implemented where an anaerobic (sulfidic) bioreactor was incorporated as an addition to a micro-oxic bioreactor, allowing for higher S8 selectivity by limiting by-product formation. The highly sulfidic bioreactor environment enabled the SOB to remove (poly)sulfides (SX2−) in the absence of oxygen, with SX2- speculated as a main substrate in the removal pathway, thus making it vital to understand its role in the process. The SOB are influenced by the oxidation reduction potential (ORP) set-point of the micro-oxic bioreactor as it is used to control the product of oxidation (S8 vs. SO42−), while the uptake of SX2− by SOB has been qualitatively linked to pH. Therefore, to quantify these effects, this work determined the concentration and speciation of SX2- in the biological desulfurization process under various pH values and ORP set-points. The total SX2- concentrations in the sulfidic zone increased at elevated pH (8.9) compared to low pH (< 8.0), with on average 3.3 ± 1.0 mM-S more Sx2−. Chain lengths varied, with S72− only doubling in concentration while S52− increased 9 fold, which is in contrast with observations from abiotic systems. Changes to the ORP set-point of the micro-oxic reactor did not produce substantial changes in SX2- concentration in the sulfidic zone. This illustrates that the reduction degree of the SOB in the micro-oxic bioreactor does not enhance their ability to interact with Sx2− in the sulfidic bioreactor. This increased understanding of how both pH and ORP affect changes in SX2− concentration and chain length can lead to improved efficiency and design of the dual-reactor biological desulfurization process.

Esters and higher alcohols regulation to enhance wine fruity aroma based on oxidation-reduction potential

Fruity aroma is a crucial element in reflecting the flavor of wine, believed to be closely linked to esters and higher alcohols associated with the oxidation-reduction potential (ORP) of wine. In this work, the impact of ORP on the production of esters and higher alcohols, and consequently the fruity aroma in Cabernet Sauvignon (CS) and Ecolly wines were investigated. Results revealed that the maximum concentration of medium-chain fatty acid ethyl esters (MCFAEEs) was achieved at −80 mV, which was 48.78% and 25.10% higher than those of the CK groups (ORP without artificial control) in CS and Ecolly wines, respectively. However, the concentrations of acetates and higher alcohols in CS were not significantly different from that in CK, while those in Ecolly were elevated. Additionally, the temperate fruity aroma in CS and citrus aroma in Ecolly wines were enhanced at −80 mV. Partial least-squares regression further indicated that, higher alcohols contributed positively to these enhanced aromas of CS and Ecolly. MCFAEEs have also been suggested to have a positive impact on the fruity and floral aromas for CS and tropical fruity aroma for Ecolly wines. Our work provides an alternative for improving the aroma quality of wine through fermentation process.

A comprehensive setting method for the optimal setpoint of controlled variables in the zinc smelting solution purification process under multi-variation inlet status

The zinc smelting solution purification process regulates the oxidation-reduction reactions (characterized by the oxidation-reduction potential (ORP)) by controlling the amount of zinc powder added to remove the impurity ions. In order to ensure the optimal operation of the process, the target key technical indicators should be converted into the optimal setpoint of controlled variables (that is, ORP). Based on the mechanism knowledge, fuzzy rules, and preference-guided predictive optimization, a comprehensive setting method for the optimal setpoint of controlled variables under multi-variation inlet status is proposed. It includes a hybrid trend detection method for inlet status, a mechanism model under multiple operating modes, and a fuzzy correction method and a preference-guided predictive optimization method to deal with slight and violent fluctuations in the inlet status, respectively. The experimental results show that the proposed method can obtain the optimal setpoint of controlled variables and reduce zinc powder consumption by approximately 3.6%.

Sulphate removal by membrane filtration minimizes the risk of hydrogen sulphide formation in fixed bed biofilters

Hydrogen sulphide (H2S) is one of the suspected reasons behind sudden mass fish mortalities in recirculating aquaculture systems (RAS) in recent years. H2S production in aquaculture systems depends on sulphate and organic matter availability, presence of specific microbial groups, and local anoxic conditions. Specific potential H2S production hotspots in RAS have been identified within biofilters and in accumulated sludge. Current H2S control methods have been identified, such as improved hydrodynamics, increasing degassing efficiency, chemical addition of hydrogen peroxide or ozone, but have not been efficient or widespread applied. In this study, a nanomembrane filtration system was installed at a brackish water (mixture of seawater and freshwater to 15 ppt) smolt production site in Norway to remove sulphate ions from the seawater intake line (15 times reduction). The hydrogen sulphide production potential of the nanofiltered seawater mixed with freshwater (n = 3) was compared to an unfiltered seawater and freshwater mixture (15 ppt, n = 3) for 42 days in experimental scale biofilters using industrial fixed bed media. In both treatments, the linear production of H2S started around the time that bulk water measurements of oxidation-reduction potential (ORP) and dissolved oxygen (DO) dropped below 0 mV and 1 mg/L, respectively. As expected, the highest H2S concentration was observed in unfiltered water reactors, which also reached the highest concentration faster than filtered-water reactors. A 15 times reduction in initial sulphate levels by the nanofiltration membrane led to overall three times lower H2S production and delayed the onset of production by two days. Hence, membrane-filtering intake water decreased the risk of H2S production. A limitation in this study, however, was that sulphate was not completely removed from the intake water, and the next steps should evaluate how increasing the effort of membrane operation to completely remove sulphate affect the dynamics of H2S production in RAS.

The ecology of the sewer systems: Microbial composition, function, assembly, and network in different spatial locations

Microbial induced concrete corrosion (MICC) is the primary deterioration affecting global sewers. Disentangling ecological mechanisms in the sewer system is meaningful for implementing policies to protect sewer pipes using trenchless technology. It is necessary to understand microbial compositions, interaction networks, functions, alongside assembly processes in sewer microbial communities. In this study, sewer wastewater samples and microbial samples from the upper part (UP), middle part (MP) and bottom part (BP) of different pipes were collected for 16S rRNA gene amplicon analysis. It was found that BP harbored distinct microbial communities and the largest proportion of unique species (1141) compared to UP and MP. The community in BP tended to be more clustered. Furthermore, significant differences in microbial functions existed in different spatial locations, including the carbon cycle, nitrogen cycle and sulfur cycle. Active microbial sulfur cycling indicated the corrosion risk of MICC. Among the environmental factors, the oxidation‒reduction potential drove changes in BP, while sulfate managed changes in UP and BP. Stochasticity dominated community assembly in the sewer system. Additionally, the sewer microbial community exhibited numerous positive links. BP possessed a more complex, modular network with higher modularity. These deep insights into microbial ecology in the sewer system may guide engineering safety and disaster prevention in sewer infrastructure.

Integration of Sensor Fusion to Enhance Quality Assessment of White Brine Cheeses

The article examines the main characteristics of white brine cheeses from different manufacturers and changes in their quality indicators. These characteristics include the active acidity, electrical conductivity, total dissolved solids, oxidation–reduction potential, and organoleptic assessment. In this context, the connection to biomimetics lies in the approach of integrating multiple sensory modalities, similar to how biological systems often use multiple senses to perceive and understand their environment. For this purpose, spectral, ultrasonic, and gas characteristics were used, from which informative indices were extracted, united at a later stage in a vector of features. Based on the classification, it was found that the optical characteristics of cheeses from different manufacturers overlap, thus making it possible to predict the main indicators for each type of cheese. The results show that the use of a multimodal approach combining features from different sensors contributes to a better understanding of the variations in cheese properties, while improving the predictive abilities of the created models. The obtained results give a clear idea of the quality of the cheese, thus enabling adequate decisions to be made during the production process.

Physicochemical and FT-IR analyses of some freshwater and inflow wastewater-treated effluents in the Eastern Cape Province of South Africa

Monitoring changes occurring in water bodies is a tool to make a sound decision on water quality management. This work investigates water quality parameters and metabolites in the Bloukrans, Buffalo, Swartkops and Tyhume Rivers in the Eastern Cape Province of South Africa. The water physicochemical parameters assessed include the dissolved oxygen, oxidation-reduction potentials, temperature, Hydrogen ion concentration, salinity, conductivity, turbidity and total dissolved solids measured with a pre-calibrated Hanna Multiparameter instrument on-site. Chemical oxygen demand, phosphate, chloride, ammonium, sulphate and nitrate ions were measured in the laboratory with a UVmini spectrophotometer. FT-IR analysis of extracted metabolites was done on a Perkin Elmer FT-IR spectrometer. The result shows that upstream river samples have lower COD values and below the detection level in some. The concentrations of phosphate, chloride, ammonium, sulphate and nitrate ions were above the recommended values in the wastewater effluents, midstream and downstream river samples. FT-IR peaks similar to vinylidene, saturated aliphatic aldehydes, aryl aldehydes, primary amines, hydantoin amides, halogen, and organofluorides were common in the wastewater effluent samples and the receiving rivers. Grahamstown treated wastewater effluents and its receiving Bloukrans River were distinguished with absorption peaks of urethane and aromatic aldehydes. Absorption peaks of sulphonyl halides were present only on the spectra of treated wastewater effluents of Alice and the receiving downstream Tyhume River. Multivariate analysis shows correlations between the water samples from different geographical locations and treated wastewater effluents. It is concluded that the quality of the rivers was very poor and more efforts are needed to make the treated wastewater conform to the acceptable standard for a sustainable aquatic ecosystem.

Palm Oil Mill Effluent Treatment Technology using Sequencing Batch Reactor (SBR) with Oxidation Reduction Potential (ORP) Monitoring

Palm oil industries have products like Crude Palm Oil (CPO), and 70% of others contain waste. One of the wastes is the liquid waste known as Palm Oil Mill Effluent (POME). The potential of POME to be reprocessed into clean water will be profitable. One of POME's reprocessing methods is the Sequencing Batch Reactor with Aerobic Granulated Sludge (SBR-AGS), which has five main phases: filling, idling, aeration, settling, and discharge, with a cycle time of 360 minutes. The first step in using this reactor is the start-up process, a granule-forming process from some sludge that has already acclimatized. In one complete cycle, the Oxidation-Reduction Potential (ORP) parameter is used to observe the electron transfer process that shows the oxygen supply into the reactor, which enables the condition of each phase in the process to be analyzed. The trend of ORP value is constantly changing in every phase. For the idling phase, the ORP tends to decrease in a value of (-300)-(-400) mV, and for the aeration phase, it will increase in a value of (-100)-100 mV.

Integration of the grey relational analysis with machine learning for sucrose anaerobic hydrogen production prediction

Anaerobic fermentation for hydrogen production is influenced by various environmental factors that can limit microbial activity. However, machine learning (ML) shows significant potential in explaining the complexity of biological processes. This study focuses on the application of ML in predicting hydrogen production rates (HPR) during anaerobic fermentation of biomass energy. Grey relation analysis was employed to investigate the correlation between operational parameters and HPR. Five ML algorithms, namely decision tree (DT), random forest (RF), extreme gradient boosting (XGBoost), and K-nearest neighbor (KNN), were utilized in conjunction with operating conditions and digestate characteristics as features, with HPR as the target variable. The evaluation of the models was conducted using mean squared error (MSE) and R squared (R2). Notably, butyrate, oxidation-reduction potential (ORP), and volatile suspended solids (VSS) were identified as key factors influencing hydrogen production during sucrose anaerobic fermentation. Among the ML algorithms tested, XGBoost achieved the highest accuracy, with an R2 value of 0.91 and an MSE of 0.0052.

Cerium oxide-based catalyst for low-temperature and efficient ammonia decomposition for hydrogen production research

This study prepared a series of cerium oxide-based catalysts with different metal ruthenium loadings using an initial wet impregnation method. The results demonstrate that the prepared 1.4Ru/CeO2 catalyst exhibits outstanding catalytic performance and activity stability. Under the condition where the Ru loading is only 1.4 wt%, the catalyst achieves almost complete NH3 conversion at 500 °C, with a hydrogen production rate of 16.59 mmol gcat−1 min−1. Furthermore, after a 48-h long-term test, the activity remains stable. Characterization tests show that the metal ruthenium is uniformly distributed on the surface of cerium dioxide, with particle sizes ranging from 3 to 6 nm. Notably, a structure characterized by lattice stripes overlapping between the metal and support is observed. Increasing the Ru loading can enhance the surface acidity sites of the catalyst and the interaction between the metal and the support, which plays a crucial role in the long-term stability of the catalyst. Additionally, the abundant oxygen vacancies in cerium dioxide and its low cerium oxidation-reduction potential facilitate electron transfer to ruthenium, enhancing the adsorption of NH3 and accelerating the desorption of N2.

Redox Behaviour and Redox Potentials of Dyes in Aqueous Buffers and Protic Ionic Liquids.

Organic dyes hold promise as inexpensive electrochemically-active building blocks for new renewable energy technologies such as redox-flow batteries and dye-sensitised solar cells, especially if they display high oxidation and/or low reduction potentials in cheap, non-flammable solvents such as water or protic ionic liquids. Systematic computational and experimental characterisation of a representative selection of acidic and basic dyes in buffered aqueous solutions and propylammonium formate confirm that quinoid-type mechanisms impart electrochemical reversibility for the majority of systems investigated, including quinones, fused tricyclic heteroaromatics, indigo carmine and some aromatic nitrogenous species. Conversely, systems that generate long-lived radical intermediates -- arylmethanes, hydroquinones at high pH, azocyclic systems -- tend to display irreversible electrochemistry, likely undergoing ring-opening, dimerisation and/or disproportionation reactions.

Mercury Bioconcentration and Translocation in Rooted Macrophytes (Paspalum repens Berg.) from Floodplain Lakes in the Araguaia River Watershed, Brazilian Savanna

Macrophytes are fundamental photosynthetic organisms for functioning freshwater ecosystems, identified as potential bioindicators of mercury (Hg) in the environment. We quantified the concentrations of total Hg (THg) in water and macrophytes (Paspalum repens Berg.) from 17 lakes on the Araguaia River floodplain, aiming to compare the bioconcentration factor (BCF) in the aerial tissues and roots; evaluate the translocation factor (TF) between plant tissues; and assess the influence of environmental factors and land use on THg concentrations in water and macrophytes. The BCF was significantly higher in roots (1.29 ± 0.32) than in aerial tissues (0.41 ± 0.34), with low TF between plant tissues (0.14 ± 0.06). The highest concentrations of THg in water were determined in lakes with higher land use intensity and a pH close to neutral, indicating the transport of particulate-bound Hg and the immobilization in the water column. In contrast, wetlands were priority areas for the bioconcentration of THg in macrophytes, associated with sulfate, dissolved oxygen, and oxidation–reduction potential in the water. Thus, although P. repens is not a suitable bioindicator of Hg mobilization by anthropogenic land use in our study area, our results suggest the potential of macrophytes as bioindicators of sites that are favorable to Hg methylation.

Undisclosed contribution of microbial assemblages selectively enriched by microplastics to the sulfur cycle in the large deep-water reservoir

The accumulation of microplastics in reservoirs due to river damming has drawn considerable attention due to their potential impacts on elemental biogeochemical cycling at the watershed scale. However, the effects of plastisphere communities on the sulfur cycle in the large deep-water reservoir remain poorly understood. Here, we collected microplastics and their surrounding environmental samples in the water and sediment ecosystems of Xiaowan Reservoir and found a significant spatiotemporal pattern of microplastics and sulfur distribution in this Reservoir. Based on the microbial analysis, plastic-degrading taxa (e.g., Ralstonia, Rhodococcus) involved in the sulfur cycle were enriched in the plastisphere of water and sediment, respectively. Typical thiosulfate oxidizing bacteria Limnobacter acted as keystone species in the plastisphere microbial network. Sulfate, oxidation reduction potential and organic matter drove the variations of the plastisphere. Environmental filtration significantly affected the plastisphere communities, and the deterministic process dominated the community assembly. Furthermore, predicted functional profiles related to sulfur cycling, compound degradation and membrane transport were significantly enriched in the plastisphere. Overall, our results suggest microplastics as a new microbial niche exert different effects in water and sediment environments, and provide insights into the potential impacts of the plastisphere on the sulfur biogeochemical cycle in the reservoir ecosystem.

Assessment of the suitability of greensand filtration for Mn removal for private wells

Greensand filtration is a common treatment option for manganese, sulfide, and iron removal; poor maintenance, however, can compromise effectiveness and even lead to increased post-treatment Mn concentrations. A private drinking-water well in exceedance of Health Canada’s maximum allowable concentration for Mn was sampled over a 1-year period to assess Mn removal via greensand filtration. Mn concentrations post-treatment were on average twofold higher than raw well water prior to media change. Reducing conditions, evidenced by negative oxidation–reduction potential (ORP) of the effluent, were central to generating soluble Mn(II). Monitoring revealed that water usage patterns caused variability in post-treatment Mn, with peak concentrations (&gt;3.5× higher than influent water) observed after a 7-day idle period. As inadequate oxidant addition can lead to reducing conditions, monitoring ORP may facilitate proxy surveillance for Mn release. Findings underscore the importance of human factors (e.g., aesthetic concerns, barriers to maintenance, perceived risk) when evaluating overall benefits and drawbacks of treatment systems.

Co-migration behavior of toluene coupled with trichloroethylene and the response of the pristine groundwater ecosystems – A mesoscale indoor experiment

Experimental scale and sampling precision are the main factors limiting the accuracy of migration and transformation assessments of complex petroleum-based contaminants in groundwater. In this study, a mesoscale indoor aquifer device with high environmental fidelity and monitoring accuracy was constructed, in which dissolved toluene and trichloroethylene were used as typical contaminants in a 1.5-year contaminant migration experiment. The process was divided into five stages, namely, pristine, injection, accumulation, decrease, and recovery, and characteristics such as differences in contaminant migration, the responsiveness of environmental factors, and changes in microbial communities were investigated. The results demonstrated that the mutual dissolution properties of the contaminants increased the spread of the plume and confirmed that toluene possessed greater mobility and natural attenuation than trichloroethylene. Attenuation of the contaminant plume proceeded through aerobic degradation, nitrate reduction, and sulfate reduction phases, accompanied by negative feedback from characteristic ion concentrations, dissolved oxygen content, the oxidation-reduction potential and microbial community structure of the groundwater. This research evaluated the migration and transformation characteristics of typical petroleum-based pollutants, revealed the response mechanism of the ecosystem to pollutant, provided a theoretical basis for predicting pollutant migration and formulating control strategies.

Impact of sand media continuous drying and rewetting cyclic on nutrients transformation performance from reclaimed wastewater effluent at soil aquifer treatment

Reusing reclaimed wastewater became a practical resource for water utilization in groundwater recharge and irrigation activities. However, the quality of reclaimed wastewater needs improvement to meet the environmental regulations and reduce contamination risks. A laboratory-scale study simulated a soil aquifer treatment (SAT) system, exploring the synergistic effects of wet and dry cycles alongside key physicochemical parameters on pollutant removal efficiency using a glass column filled with quartz sand as the filtration medium. The investigation focused on the cyclic wetting and drying phases to unravel their impact on removing NH4+, NO3−, and PO43−. The synthetic wastewater introduced into the system exhibited varying pollutant concentrations during wet and dry periods, influenced by dynamic soil water content (WC%), pH, dissolved oxygen (DO), and oxidation–reduction potential (ORP). The high removal rates of 93% for PO43− and 43% for Total N2 demonstrate the system’s capability to reduce concentrations significantly under dynamic alternating between wet and dry conditions. Results unveiled that the wet period consistently yielded higher removal rates for N2 species. Interestingly, for PO43−, the dry periods demonstrated a higher removal efficiency. Moreover, the study identified an average NO3− production during the experimental phases as a byproduct of nitrification. The average NO3− production in wet periods was 2.5 mg/L, whereas it slightly decreased to 2.2 mg/L in dry periods. These findings underscore the nuanced influence of wet and dry conditions on specific pollutants within SAT systems. Applying the logistic regression model and principal component analysis demonstrated the statistical significance of WC, pH, DO, and ORP in predicting wet/dry conditions, providing quantitative insights into their influential roles on the nutrient dynamic concentrations. This study contributes valuable data to our understanding of SAT systems, offering practical implications for designing and implementing sustainable wastewater treatment practices and pollution management across diverse environmental contexts.