High Nitrite Concentrations Research Articles

Towards citizen science. On-site detection of nitrite and ammonium using a smartphone and social media software

Citizen scientists-based water quality surveys are becoming popular because of their wide applications in environmental monitoring and public education. At present, many similar studies are reported on collecting samples for later laboratory analysis. For environmentally toxic analytes such as ammonium and nitrite, on-site detection is a promising choice. However, this approach is limited by the availability of suitable methods and instruments. Here, a simple on-site detection method for ammonium and nitrite is reported. The chemistry of this method is based on the classic Griess reaction and modified indophenol blue reaction. Digital image colorimetry is carried out using a smartphone with a custom-made WeChat mini-program or free built-in applications (APPs). Using a simple and low-cost analytical kit, the detection limit of 0.27 μmol/L and 0.84 μmol/L is achieved for nitrite and ammonium, respectively, which are comparable to those achieved with a benchtop spectrophotometer. Relative standard deviations (n = 7) for low and high concentrations of nitrite are 3.6% and 4.3% and for ammonium are 5.6% and 2.6%, respectively. Identical results with a relative error of less than 10% are obtained using different smartphones (n = 3), color extracting software (n = 6), and with multiple individual users (n = 5). These results show the robustness and applicability of the proposed method. The on-site application is carried out in an in-campus wastewater treatment plant and at a local river. A total of 40 samples are analyzed and the analytical results are compared with that obtained by a standard method and a spectrophotometer, followed by a paired t-test at a 95% confidence level. This proposed on-site analytical kit has the advantages of simplicity and portability and has the potential to be popular and useful for citizen science-based environmental monitoring.

Study on Mechanism and Application of High Concentrations of Nitrite-Induced Specific Color Fading

Nitrite and edible salt are easy to confuse for their similar appearance and taste, thus possibly causing nitrite poisoning. Therefore, it is particularly crucial to figure out how to screen high concentrations of nitrite, how to discriminate NaNO₂ and NaCl, and how to accurately quantify high concentrations of nitrite. In this study, the phenomenon of high concentrations of nitrite fading to orange-yellow color in colorimetric solution of naphthalene ethylenediamine hydrochloride was studied and accurately quantified by dilution colorimetry. It is to prevent false negative detection while NaCl presented no such phenomenon. Through spectrophotometry, high-performance liquid chromatography, and liquid mass spectrometry, we discovered that the principle of high concentrations of nitrite fading to orange-yellow after colorimetry was that high concentrations of nitrite nitrosated azo compounds and naphthalene ethylenediamine hydrochloride in hydrochloric acid medium. This principle can make the solution appear orange-yellow while had almost no matrix interference and this demonstrates no difference in food and water. We thus argue that this principle can be used for the screening of high concentrations of nitrite, and discriminating NaNO₂ and NaCl to prevent poisoning events caused by misuses. In this sense, we believe the principle in question has a high applying value and is worth promoting. It can be made into a commercial hydrochloric acid acidified naphthylethylenediamine hydrochloride solution for further commercialized applications.

Effect of the Site and the Type of Fertilizer on the Taxonomic Composition and Abundance of Phytoplankton Population of Ponds in West Cameroon

Pond fertilization is an age-old practice aimed at optimizing yields in so-called production fish farming systems. With this in mind, a characterization study of phytoplankton, the basis of the trophic food chain leading to fish, was conducted from January to December 2021 in ponds in the West Cameroon regionand at the Research Unit of Ichthyology and Applied Hydrobiology of the University of Dschang. To do this, a total of fifteen (15) ponds including 03 in Bamendou fertilized with cowpat, 04 in Batie including 02 fertilized with pig manure and 02 with wheat bran, 01 in Dschang fertilized with chicken manure, 04 in Fokoue including 02 fertilized with pig manure and 02 unfertilized and 03 in Foumbot fertilized with cowpat, were considered. These ponds were chosen based on the availability of fish farmers and the type of fertilizer administered. Sampling of biotic characteristics including phytoplankton richness, relative abundance and density was done between 6 and 8 a.m. following a monthly frequency. The results showed that the highest specific richness (42.73% of total species richness) was observed in Batie ponds fertilized with pig manure and generic richness (81.53% of total genera richness) and families (84.21% oftotal of families richness) highest phytoplankton in Batie ponds fertilized with wheat bran. Regardless of the type of pond, Chlorophyta were more abundant (40.50%). With the exception of Chrysophyta who were absent in the ponds of Foumbot fertilized with cowpat, all other groups were listed in the different types of ponds. The significantly (p<0.05) highest phytoplankton density (71. 107 ind/L) was observed in ponds fertilized with chicken manure with high concentrations of nitrates and nitrites.

Effect of tidal resuspension with oyster biodeposits on nutrient and oxygen dynamics

To test the effect of biodeposit resuspension on nutrient and oxygen dynamics, we performed a 30 d experiment in three 1000 l shear turbulence resuspension mesocosm (STURM) tanks (R) and three 1000 l non-resuspension (NR) tanks. All tanks contained defaunated muddy sediment and brackish estuarine water, received daily additions of oyster biodeposits, and had similar water column root mean square turbulent velocities (~1 cm s-1), energy dissipation rates (~0.08 cm2 s-3), and tidal cycles (4 h mixing-on; 2 h mixing-off). While bottom shear stress was low in NR tanks, high instantaneous bottom shear produced sediment and biodeposit resuspension in R tanks during the mixing-on cycles. Resuspension and biodeposit addition resulted in complex nutrient and oxygen dynamics in the water column as well as altered seabed fluxes. Modeled biodeposit diagenesis demonstrated that added resuspended biodeposit nitrogen in R tanks was nitrified, resulting in high water column nitrate and nitrite concentrations, as well as increasing water column dissolved oxygen demand. Water column dissolved oxygen concentrations were 2.3 times lower in the R tanks than in the NR tanks, whereas deposited organic matter from biodeposits resulted in sediment dissolved oxygen uptake 3 times higher in NR versus R tanks. Sediment dissolved inorganic nitrogen uptake in NR tanks and efflux in R tanks, respectively, were mediated by microphytobenthos abundance and biodeposit deposition. Seabed and water column biogeochemical processes, as mediated by biodeposit resuspension, controlled the nutrient and oxygen balances. Biodeposit resuspension is important when evaluating oysters as support for eutrophication control.

Identification of the nitrate and nitrite content in leafy vegetables from the city of Zliten

تقدر الدراسة محتوى النترات (NO3) والنتريت (NO2) في الخضار الورقية (البقدونس، السلق، الكزبرة) في ثلاث مناطق زراعية في زليتن (أزدو، الدفنية، ماجر))، باستخدام جهاز colorimeter dr / 980، وتقييم ما إذا كان المحتوى ضمن التركيزات المسموح بها نسبيًا. تظهر النتائج التي تم الحصول عليها من هذه الدراسة أن تركيزات النترات في جميع العينات التي تم فحصها ضمن المعايير العالمية، مع أعلى مستوى من 5.5 جزء في المليون وجدت في عينات السلق التي تم جمعها من منطقة أزدو. أما بالنسبة للنتريت فالتركيزات الموجودة في العينات المدروسة أعلى من تركيزات النترات. بشكل عام، وجد أن محتوى النترات والنتريت ضمن التركيزات المسموح بها بناءً على المعايير الدولية، حيث يتم تسجيل أعلى تركيز من النتريت 60 جزء في المليون في عينات البقدونس من منطقة الدفنية.

Gene expression analysis of Alcaligenes faecalis during induction of heterotrophic nitrification

Alcaligenes faecalis is a heterotrophic nitrifying bacterium that oxidizes ammonia and generates nitrite and nitrate. When A. faecalis was cultivated in a medium containing pyruvate and ammonia as the sole carbon and nitrogen sources, respectively, high concentrations of nitrite accumulated in the medium whose carbon/nitrogen (C/N) ratio was lower than 10 during the exponential growth phase, while the accumulation was not observed in the medium whose C/N ratio was higher than 15. Comparative transcriptome analysis was performed using nitrifying and non-nitrifying cells of A. faecalis cultivated in media whose C/N ratios were 5 and 20, respectively, to evaluate the fluctuations of gene expression during induction of heterotrophic nitrification. Expression levels of genes involved in primary metabolism did not change significantly in the cells at the exponential growth phase under both conditions. We observed a significant increase in the expression levels of four gene clusters: pod cluster containing the gene encoding pyruvic oxime dioxygenase (POD), podh cluster containing the gene encoding a POD homolog (PODh), suf cluster involved in an iron-sulfur cluster biogenesis, and dnf cluster involved in a novel hydroxylamine oxidation pathway in the nitrifying cells. Our results provide valuable insight into the biochemical mechanism of heterotrophic nitrification.

Plasma activated water prepared by different plasma sources: physicochemical properties and decontamination effect on lentils sprouts

The pulsed corona discharge (CD) generated in contact with water and directly in water, and high-power air plasma jet (APJ) were studied for production of plasma activated water (PAW). The changes of physical (pH, redox potential, conductivity, temperature) and chemical (peroxides, nitrites, nitrates concentrations) properties of treated water were investigated. The comparison of CD generated in gas/water interface and underwater configuration in the same system showed that the interaction of reactive oxygen and nitrogen species formed in ambient air in gas/water system induces different chemical processes, leading to lower pH, higher oxidation-reduction potential (ORP) and higher conductivity of PAW than in underwater discharge. High yield of peroxide was observed in both configurations. The PAW prepared by APJ exhibits high concentration of nitrites and nitrates according to supplied energy, and related significant decrease of pH and increase of ORP and conductivity after treatment. The antimicrobial effect of PAW prepared by CD and plasma jet on lentils sprouts was studied in different treatment and washing times. The APJ appears to have great efficacy on water activation resulted in strong decontamination effect. The PAW treated by APJ for 10 min led to bacterial reduction from initial 8.3 to 5.9 and 4.0 log10 CFU g−1 after 10 and 30 min of washing, respectively.

Diatoms contributing to new production in surface waters of the northern Bering and Chukchi Seas during summer with reference to water column stratification

Intensive phytoplankton blooms, which mainly consist of diatoms, take place in the northern Bering and Chukchi Seas from spring to summer. Little is known, however, about the diatoms contributing to new production in these waters during summer when the water column is often stratified. In this study, using a 13C, 15N dual isotope tracer technique plus scanning electron microscopy, we assessed the diatom genera or species contributing to new production in surface waters of the northern Bering and Chukchi Seas in July 2013. Relatively high concentrations of nitrate, nitrite, phosphate, and silicate were observed at Bering Strait and Chukchi Shelf stations, whereas at the other stations surface nitrate was generally depleted. Surface ammonium levels were relatively high (0.05–1.52 µM), suggesting the high activity of heterotrophic organisms. In surface waters, hourly nitrate uptake rates ranged from 0.03 to 3.73 mg N m−3h−1, while the ammonium uptake rates varied between 0.04 and 0.43 mg N m−3h−1. As a result, the mean f-ratio was computed as 0.62 ± 0.23 during observation. We found that the nitrate uptake rates were positively correlated with ambient nitrate levels, indicating that the activity was mainly regulated with the physical process of nitrate supply. The diatom Chaetoceros (mainly C. socialis/gelidus) numerically dominated the surface diatom assemblages. Contributions of C. socialis/gelidus (9 ± 4 µm in size) to the total armored phytoplankton abundance increased with an increase in the water column stratification, whereas Thalassiosila spp. (26 ± 8 µm) showed the opposite trend. These results were consistent with the survival strategy of small diatoms for nutrient uptake in oligotrophic waters through their higher cell surface area to volume ratios. On the other hand, the carbon biomass of Thalassiosira became relatively high in surface waters, and significantly correlated with f-ratio. We conclude that the centric diatom Thalassiosira plays a key role in determining new production in surface waters of the study area during summer.

Chemical and ecological quality of water and bottom sediments in small rivers of Belgorod oblast

Belgorod Oblast has limited water resources. The paper explores the chemical and ecological characteristics of water and bottom sediments in the Oskol River tributaries. In samples of water taken from small rivers, Maximum Allowable Concentrations (MAC) for pollutants was excessive, including suspended matter, ammonium ions, nitrite ions, phosphate ions, BOD5 and mineral elements. A hydrochemical water pollution index (WPI6) ranges from 1.0 to 1.9, which characterizes water bodies in the categories from clean to moderately polluted watercourses. A comparatively high WPI6 index is recorded in summer for the Kotel River – 1.4, for the Belenkaya River – 2.3, which is attributed to a high concentration of ammonium ions, nitrites and phosphates found to be present in the water. This indicates recent pollution and a changing trophic status of the reservoir. The amount of metals in river water exceeds the MAC norms: for iron – 1.7 -6 MAC; for copper – 1.6 - 8 MAC; for manganese – 0.8 - 22 MAC; for zinc – 1.9 - 9.9 MAC. Concentrations of micronutrients are subject to significant seasonal fluctuations. No excess of lead is found to be present in surface waters. In the samples of bottom sediments taken from the Oskol River tributaries, no excess of MAC values is found, except for lead (1.1 - 2.9 MAC), manganese (1.6 - 2.2 MAC), copper (1.2 - 1.6 MAC) and phosphate ions (1.3 - 2.3 MAC). It is obvious that the sources of pollution for small rivers are runoffs from agricultural land, livestock farms and household wastewater of nearby settlements.

Effects of ammonia and nitrite on food consumption of the Amazon River prawn Macrobrachium amazonicum (Heller, 1862) postlarvae

Experiments were carried out to study the effects of ammonia and nitrite on food consumption of Macrobrachium amazonicum postlarvae. Postlarvae (average weight of 0.0625 g) were exposed during 21 days to four concentrations of total ammonia (0, 1.05, 2.1 and 4.2 mg. NH3+NH4+ L-1) and four concentrations of nitrite (0, 0.075, 0.15 and 0.30 mg N-NO2- L-1). After the exposure period, six prawns per treatment were maintained individually in 250 mL experimental units to analyze the food consumption as a function of the amount of food offered and the leftovers during a 24 h period. The food consumption presented significant alterations for prawns exposed to all nitrite concentrations and at concentrations of twice the recommended safety level for total ammonia. According to the results obtained, high concentrations of total ammonia and nitrite affect the food consumption of M. amazonicum adversely, influencing the species performance in culture systems.

Effect of cell-permeable grouper Manganese Superoxide Dismutase on environmental stress in fish

Nitrite levels are generally high in high-density aquaculture. Nitrite is a potential stress-inducing factor and can cause oxidative stress because excessive reactive oxygen species (ROS) formation through nitrite induction cannot be scavenged by the endogenous antioxidant system, thus leading to cell damage or death. Manganese Superoxide Dismutase (MnSOD) is a highly efficient endogenous ROS scavenger that quenches mitochondrial ROS and protective against oxidative stress. To enhance the efficiency of MnSOD in removing ROS and reducing oxidative caused by nitrite, in this study, we cloned grouper MnSOD (gMnSOD) fused with a cell-penetrating peptide, TAT, to construct a TAT-gMnSOD fusion protein and assessed its potential to eliminate excess ROS induced by high nitrite concentrations and enhance the resistance of zebrafish to environmental stressors. Our results revealed that TAT-gMnSOD penetrated the grouper fin (GF-1) cells, scavenged nitrite-induced intracellular ROS, and enhanced cell viability on NaNO2 treatment. Furthermore, pretreatment of zebrafish with TAT-gMnSOD fusion protein reduced the MDA content and increased the survival rate. In addition, the TAT-gMnSOD fusion protein reduced 2-phenoxyethanol toxicity and attenuated excessive anesthesia among zebrafish. In conlusion, our cell-permeable TAT-gMnSOD fusion protein effectively counters oxidative stress, prevents environmental stress-induced damage, and increases aquaculture benefits.

Optimizing the application of plasma functionalised water (PFW) for microbial safety in fresh-cut endive processing

The microbiological profiles and responses of native microflora of endive were investigated using a model process line, to establish where a defined PFW should be optimally applied to retain or improve produce microbiological quality. The PFW processes were compared with tap water and ClO2. The antimicrobial efficacy of PFW was quantified by determining the reduction in microbial load, the microbial viability and vitality. Depending on the stage of application of PFW, up to 5 log10-cycles reduction was achieved, accompanied by a reduction of metabolic activity, but not necessarily with a decrease in metabolic vitality. Multiple application (3-step-PFW-application) was more effective than single application (1-step-PFW-application) and PFW showed stronger antimicrobial effect in pre-cleaned endive. High concentrations of nitrite (315 mg l−1) and nitrate (472 mg l−1) in PFW were the main factors for the antimicrobial efficacy of PFW against bacteria. Furthermore, H2O2 and an acidic pH supported the mechanism of action against the endive microflora. These results identify the pathway to scale up successful industrial application of PFW targeting microbiological quality and safety of fresh leafy products. Industrial relevanceThe safety, quality and shelf life of freshly cut vegetables, e.g. lettuce, are strongly influenced by the microbial load. In addition, the hygienic design of production line, and a good handling/ production practice are indispensable. This study shows that the application of PFW, as a promising non-thermal sanitation technology, enables the inactivation of native microbial contamination on fresh-cut endive depending on the process stage of application. It further describes the impact of PFW on the metabolic activity and metabolic vitality of the lettuce-associated microflora. For higher acceptance, the mechanism of action of PFW was assumed based on previous chemical analyses and compared to the industrial standard of ClO2. The results contribute to the understanding and product-specificity of PFW-induced effects on safety, quality and shelf life of fresh cut lettuce and could be a basis for a possible industrial implementation and complement of common technologies.

Whole genome sequencing of Lactobacillus plantarum DMDL 9010 and its effect on growth phenotype under nitrite stress

The nitrite that normally exists in fermented foods is a threat to public health. Nitrite degradation by lactic acid bacteria (LAB) has the advantages of safety and low cost. This study investigated the effect of Lactobacillus plantarum DMDL 9010 (LP9010) on growth phenotype under nitrite stress from the perspective of whole genome sequencing. The results showed that LP9010 has certain tolerance to nitrite. However, high nitrite concentration (5–12.5 mmol/L) inhibited the growth and acid production. Nitrite could not only affect the morphology of LP9010 cells with longer phenotype, shrink and dent on the surface (even crack), but also decreased cell surface hydrophobicity. Correspondingly, 19 genes encoding stress proteins have been found in the genome. In addition, genes related to osmotic regulation proteins and peptidoglycans synthesis were found in the genome of LP9010, which may affect the cell wall structure under nitrite stress. Low pH lactic acid could degrade nitrite, whereas nitrite was hardly degraded when pH > 4. In addition, we found the putative nitrite reductase gene in LP9010, the nitrite ion bound to the Cd1NiR (pgl) active site by forming two hydrogen bonds with the residues PRO87 and PRO88. This study could provide theoretical reference to reduce nitrite in food products.

Cold Atmospheric Pressure Plasma-Activated Medium Induces Selective Cell Death in Human Hepatocellular Carcinoma Cells Independently of Singlet Oxygen, Hydrogen Peroxide, Nitric Oxide and Nitrite/Nitrate.

Cold atmospheric pressure plasma (CAP) and plasma-activated medium (PAM) induce cell death in diverse cancer cells and may function as powerful anti-cancer agents. The main components responsible for the selective anti-cancer effects of CAP and PAM remain elusive. CAP or PAM induces selective cell death in hepatocellular carcinoma cell lines Hep3B and Huh7 containing populations with cancer stem cell markers. Here, we investigated the major component(s) of CAP and PAM for mediating the selective anti-proliferative effect on Hep3B and Huh7 cells. The anti-proliferative effect of CAP was mediated through the medium; however, the reactive oxygen species scavenger N-acetyl cysteine did not suppress PAM-induced cell death. Neither high concentrations of nitrite or nitrite/nitrate nor a low concentration of H2O2 present in the PAM containing sodium pyruvate affected the viability of Hep3B and Huh7 cells. Inhibitors of singlet oxygen, superoxide anions, and nitric oxide retained the capacity of PAM to induce anti-cancer effects. The anti-cancer effect was largely blocked in the PAM prepared by placing an aluminum metal mesh, but not a dielectric PVC mesh, between the plasma source and the medium. Hence, singlet oxygen, hydrogen peroxide, nitric oxide, and nitrite/nitrate are not the main factors responsible for PAM-mediated selective death in Hep3B and Huh7 cells. Other factors, such as charged particles including various ions in CAP and PAM, may induce selective anti-cancer effects in certain cancer cells.

Correlation of Nitrite and Ammonia with Prevalence of Enterocytozoon hepatopenaei (EHP) in Shrimp (Litopenaeus vannamei) on Several Super-Intensive Ponds in East Java, Indonesia

AbstractEnterocytozoon hepatopenaei (EHP), a microsporidia parasite known to hinder shrimp growth by infecting its hepatopancreas, is recently an emerging infection for Litopenaeus vannamei farms in Indonesia. The present study was conducted to investigate the relationship between nitrite and ammonia concentration with EHP infection in the super-intensive ponds. Shrimps and water samples were collected from six ponds in aquaculture super-intensive ponds with a stocking density of 5,000 shrimps in each pond which is located in Pasuruan, Lamongan, and Tuban Regency, Indonesia. The water sample was taken to the laboratory for the measurement of ammonia and nitrite. The samples of ammonia and nitrite were detected by spectrophotometer, and the PCR was used to detect 18S rRNA of EHP. The PCR analysis that showed two positive samples of L. vannamei, from the ponds with a high concentration of ammonia and nitrite, were infected by EHP. The statistical analysis showed a significant correlation between ammonia and nitrite with the prevalence of EHP infections, where the Pearson correlation (r) was 0.980 and 0.943, respectively. There was a high prevalence of EHP infection with the increase in nitrite concentration and ammonia in pond four and pond six. The concentration of over 1mg/l of ammonia and nitrite could influence EHP infection prevalence in the shrimp farms. Highlight ResearchAmmonia and nitrite concentration influence the prevalence of Enterocytozoon hepatopenaei infection in Super intensive ponds.The estimated prevalence of Enterocytozoon hepatopenaei was 16.7%.PCR amplification analysis was used to detect the 18S ss-rRNA of Enterocytozoon hepatopenaei and 510-bp was obtained.

Nitrite Concentration Analysis using Spectrophotometry on Locally Processed Meat Products in a Province in the Philippines

To examine the nitrite content of meat products is essential to protect consumers from potential health risks. This study evaluated the nitrite concentrations of chorizo and longaniza products as preservatives in cured chorizo and longaniza in Zamboanga del Sur, Philippines. The descriptive and comparative quantitative research methods were used to examine the nitrite concentration. A kilogram of each of the samples of chorizo and longaniza products were randomly taken from the public market of Dumingag, Molave, and Pagadian City. These samples were analyzed to determine the nitrite concentration spectrophotometrically. The tests showed that chorizo samples from A, B, C, D, E, F, G, and H have nitrite concentrations below the allowable or standard level. In contrast, the sample I result showed a high concentration of nitrite, very far above the Meat Inspection Regulations Standard (MRI) and Food and Drug Administration (FDA) level within a nitrite concentration of 13.4 mg Nitrite (NO2) per 100.0 grams of cured meat. On the other hand, longaniza samples J, K, and L have nitrite concentrations below the standard level, while samples M and N have nitrite concentrations above the standard. These results indicate that chorizo and longaniza products sold in the said market have not met the FDA’s standards and are unsafe for human consumption.

Multiple electron acceptor-mediated sulfur autotrophic denitrification: Nitrogen source competition, long-term performance and microbial community evolution

Sulfur-driven autotrophic denitrification (SDAD) is feasible for the treatment of low-C/N-ratio and sulfur-laden wastewaters. The nitrite accumulated in SDAD will affect the performance and stability of the system but can be a potential electron acceptor. Thus, single- and multiple-electron acceptor-mediated SDAD systems were investigated. Batch assays revealed that nitrite and nitrate were the preferential options in the SDAD system with single and multiple electron acceptors, respectively. Synchronous nitrogen and sulfur removal was successfully achieved in continuous flow experiments with multiple electron acceptors, and the system could adapt well to high concentrations of sulfide, nitrate and nitrite (i.e., 720, 108 and 64.8 mg L-1, respectively), with the predominant genera shifting from Thiobacillus (48.88%) at the initial stage to unclassified_p_Firmicute (34.24%) and Syner-01 (12.31%) at the last stage. This work provides a fundamental basis for applying and regulating SDAD with multiple electron acceptors for the remediation of nitrogen- and sulfide- laden wastewaters.

Performance optimization of a chitosan/anammox reactor in nitrogen removal from synthetic wastewater

Anaerobic ammonia oxidation (anammox) is an environmentally friendly, cost-effective, and biological method for nitrogen treatment from aqueous solutions. However, slow growth rate, negative effects of high concentration of nitrite, ammonia and other pollutants (such as metals) on anammox activity are the main drawbacks of using anammox. Thus, in this study, anammox was attached on chitosan to improve anammox performance. Two reactors comprising chitosan and anammox bacteria (first reactor, chitosan/anammox) and solely anammox (second reactor, control) were run for 73 d. The nitrogen loading rate (NLR) varied from 2 to 14 (gN/L/d), while the nitrogen concentration varied from 80 to 700 mg/L. The chitosan/anammox reactor showed a better performance than the sole anammox (control), with respective maximum abatement values of ammonia (NH4+), nitrite (NO2-), and total nitrogen (TN) of 90.8%, 83.5%, and 81.7% on days 20–25 under a NLR of 8–10 kgTN/(m3 d). Response surface methodology (RSM) was employed to optimize the performance of both reactors, and a reasonable R2 value showed that the RSM well optimized the performance of the reactors. After finding the optimum performance conditions for both reactors, Fe and Cu (0.5–7.0 mg/L) were added to the influent to monitor the effects of metals on the performance of both reactors. The performance of both reactors decreased to 0% following the addition of 7.0 (first reactor) and 6.5 (second reactor) mg/L Cu and Fe, respectively. This indicated that chitosan not only enhanced nitrogen removal by anammox but also improved the resistance of anammox to metals.

The Effect of Plasma Treated Water Unit Processes on the Food Quality Characteristics of Fresh-Cut Endive.

This study evaluated the impact of a defined plasma treated water (PTW) when applied to various stages within fresh-cut endive processing. The quality characteristic responses were investigated to establish the impact of the PTW unit processes and where PTW may be optimally applied in a model process line to retain or improve produce quality. Different stages of application of PTW within the washing process were investigated and compared to tap water and chlorine dioxide. Fresh-cut endive (Cichorium endivia L.) samples were analyzed for retention of food quality characteristics. Measurements included color, texture, and nitrate quantification. Effects on tissue surface and cell organelles were observed through scanning electron and atomic force microscopy. Overall, the endive quality characteristics were retained by incorporating PTW in the washing process. Furthermore, promising results for color and texture characteristics were observed, which were supported by the microscopic assays of the vegetal tissue. While ion chromatography detected high concentrations of nitrite and nitrate in PTW, these did not affect the nitrate concentration of the lettuce tissue post-processing and were below the concentrations within EU regulations. These results provide a pathway to scale up the industrial application of PTW to improve and retain quality characteristic retention of fresh leafy products, whilst also harnessing the plasma functionalized water as a process intervention for reducing microbial load at multiple points, whether on the food surface, within the process water or on food-processing surfaces.

Multivariate Spatial and Temporal Analysis to Study the Variation of Physico-Chemical Parameters in Litani River, Lebanon

Water quality of Litani River was deteriorated due to rapid population growth and industrial and agricultural activity. Multivariate analysis of spatio-temporal variation of water quality is useful to improve the projects of water quality management and treatment of the river. In this work, analysis of samples from different locations at different seasons was investigated. The spatio-temporal variation of physico-chemical parameters of the water was determined. A total of 11 water quality parameters were monitored over 12 months during 2018 at 3 sites located in different areas of the river. Multivariate statistical techniques were used to study the spatio-temporal evolution of the studied parameters and the correlation between the different factors. Principal Component Analysis (PCA) was applied to the responsible factors for water quality variations during wet and dry periods. The multivariate analysis of variance (MANOVA) was also applied to the same factors and gives the best results for both spatial and temporal analysis. A black point of agricultural, industrial and sewage water pollution was identified in Jeb-Jennine station from the high concentrations of ammonia, sulfate and phosphate. This difference was proved by the major changes in the values of the parameters from one station to the other. Jeb-Jennine represents a main pollution area in the river. The high ammonia, sulfate and phosphate concentrations result from the important agricultural, industrial and sewage water pollution in the area. A high bacterial activity was highlighted in Jeb-Jennine and Quaroun stations because of the presence of the high nitrite concentrations in the two locations. All parameters are highly affected by climate factors, especially temperature and precipitation. TDS, salinity, electrical conductivity and the concentrations of all pollutants increase during wet season affected by the runoff. Other factors can affect the water quality of the river for example geographical features of the region and seasonal human activity like tourism. The correlation between different parameters was evaluated using PCA statistical method. This correlation is not stable, and evolves between wet and dry season.