Wet Digestion Research Articles

Insights into the Acute Stress of Glutaraldehyde Disinfectant on Short-Term Wet Anaerobic Digestion System of Pig Manure: Dose Response, Performance Variation, and Microbial Community Structure

The outbreak of epidemics such as African swine fever has intensified the use of disinfectants in pig farms, resulting in an increasing residual concentration of disinfectants in environmental media; however, the high-frequency excessive use of disinfectants that damage pig farm manure anaerobic fermentation systems and their mechanisms has not attracted enough attention. Especially, the complex effects of residual disinfectants on anaerobic fermentation systems for pig manure remain poorly understood, thus impeding the application of disinfectants in practical anaerobic fermentation systems. Herein, we explored the effects of glutaraldehyde disinfectant on methane production, effluent physicochemical indices, and microbial communities in a fully automated methanogenic potential test system (AMPTSII). The results show that adding glutaraldehyde led to remarkable alterations in methane production, chemical oxygen demand (COD), volatile solids (VS), and polysaccharide and phosphorus concentrations. During the anaerobic process, the production of methane displayed a notable decrease of 5.0–98% in all glutaraldehyde treatments, and the trend was especially apparent for treatments containing high levels of glutaraldehyde. Comparisons of the effluent quality showed that in the presence of 0.002–0.04% glutaraldehyde, the COD and total phosphorus (TP) increased by 12–310% and 15–27%, respectively. Moreover, the addition of 0.01–0.08% glutaraldehyde decreased the ammonium (NH4+-N) concentration and VS degradation rate by 7.7–15% and 4.9–26.2%. Furthermore, microbiological analysis showed that the glutaraldehyde treatments had adverse effects on the microbial community. Notably, certain functional bacteria were restrained, as highlighted by the decreases in relative abundance and microbial diversity by 1.3–17% and 0.06–21%, respectively. This study provides a theoretical basis for the rational use of disinfectants in anaerobic fermentation systems.

Innovative system to maximize methane production from fruit and vegetable waste.

Anaerobic digestion of fruit and vegetable waste (FVW) offers an environmentally friendly alternative for waste disposal, converting it into methane for energy recovery. Typically, FVW digestion is conducted in a continuously stirred tank reactor (CSTR) due to its ease of use and stability with solid concentrations between 5 and 10%. However, CSTRs are limited to organic loading rates (OLRs) of about 3kg COD/m3.day, resulting in large reactor volumes, low methane productivity, and costly wet digestate handling. This work introduces a novel method for methane production from FVW using a high-rate reactor system. The proposed approach involves grinding, centrifuging, and/or pressing the FVW to separate it into liquid and solid phases. The liquid phase is then digested in an up-flow anaerobic sludge blanket (UASB) reactor, while the solid phase undergoes digestion in a dry methanization reactor. A model incorporating all biological reactors was implemented in the Anaerobic Digestion Model 1 (ADM1) to provide a theoretical basis for the experimental development of this system. The current simulation scenarios offer initial references for operating the experimental system, which will, in turn, generate data for further model refinement. For instance, constrained liquid-gas mass transfer was considered for dry fermentation, with additional potential biochemical kinetic limitations to be incorporated following on experimental evidence. The success of this system could enable energy recovery in 72 Central Wholesale Markets across Brazil, offering a critical tool for planning, operating, and optimizing such systems.

Analysis and Detection of Heavy Metals Content in Some Selected Packaged Fruit Juices of Kathmandu City by Flame Atomic Absorption Spectroscopy

The determination of level of heavy metals in packaged fruit juices is crucial, as extended exposure to even small quantities of these toxic element can cause severe health issues and chronic poisoning. Hence, it is essential to gather comprehensive data on the presence of heavy metals in packaged fruit juice samples. The objective of this research work is to determine heavy metals (Fe, Cu, Zn and Pb) in four different types of packaged fruit juice samples viz Apple, Mango, Orange and Lychee of four different popular brands bought from retail market of Kathmandu city by flame atomic absorption spectroscopy and compare with acceptable limit set by WHO/FAO. Wet acid digestion method was used for digestion process of packaged fruit juice samples. The concentration of Iron were ranged from 0.572-0.762mg/L in Orange juices; 0.362-0.624mg/L in Mango juices; 0.277-3.649mg/L in Apple juices; 0.279-1.770mg/L in Lychee juices respectively. Copper concentration were ranged from not detected (ND)-0.574mg/L in Orange juices; ND for all selected samples in Mango juices; ND- 0.023mg/L in Apple juices; ND-0.041mg/L in Lyclee juices. Similarly Zinc concentration were ranged from 0.0511-0.2026mg/L in Orange juices; ND-0.0700mg/L in Mango juices; ND for all selected samples in Apple juices; ND-0.0287mg/L in Lychee juices. The concentration of hazardous element Lead was found below detection limit in all selected packaged fruit juice samples. The heavy metals concentration in selected brand of packaged fruit juice samples was in following order: Fe>Zn>Cu> Pb. Int. J. Appl. Sci. Biotechnol. Vol 12(3): 158-165.

Assessment of some heavy metals for their potential health implications in the skin whitening creams available in Pakistani cosmetic market

ABSTRACT Skin whitening creams may contain impermissible levels of toxic metals, especially the non-regulated products. The present work aims to check the quality of selected skin whitening products sold in Sargodha, Pakistan for their heavy metals content because these products are in direct and in frequent contact with the skin and mucous membranes causing hazardous effects. Quantification of the metals under study was made using flame atomic absorption spectrophotometry after wet digestion of the samples. The results show that the concentrations of heavy metals are ranked as follows: As (263 ppm) > Pb (26 ppm) > Cr (2 ppm) > Cu (0.7 ppm) > Cd (not detected). The calculated p value of 0.00 (>0.05) depicts a significant difference in the levels of heavy metals in the same creams and for the same metal among different creams. The normality of the data was checked by the Kolmogorov-Smirnov and Shapiro–Wilk tests, while metal-to-metal correlation was determined by the Pearson Correlation Coefficient. Comparison of the results with limitations set by the international regulatory bodies showed that the levels of As, Pb and Cr in these creams are above the safety limits. A strict monitoring is suggested during the manufacturing process to avoid any detrimental effects.

Detection and assessment of heavy metals concentration in wheat leaves collected from the vicinity of Sahiwal coal power plant, Pakistan, employing a modern data analysis approach

ABSTRACT Heavy metal pollution in food crops has become a global issue, especially in staple crops like wheat and rice. Electricity production utilising coal, ignites this issue in crops grown in the surrounding areas of coal power plants. Keeping this view in mind, the concentration of six heavy metals (HMs) Calcium (Ca), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Lead (Pb) and Magnesium (Mg) in wheat leaves have been assessed in this study. Fifty samples of wheat leaves have been collected from the surrounding areas of the coal power plant in Sahiwal. The samples were prepared using the wet digestion method (WDM). Finally, these samples have been sent for analysis via atomic absorption spectroscopy (AAS). The limit of detection (LOD) and limit of Quantification (LOQ) of AAS were calculated with the help of blank samples. The concentration of Ca, Cd, Cr, Co, Pb and Mg in wheat leaves were 1.0187 ± 0.549 mg/kg, 0.00484 ± 0.00403 mg/kg 00,416 ± 0.00334 mg/kg, 0.0534 ± 0.0351 mg/kg, 0.035 ± 0.018 mg/kg, 0.464 ± 0.200 mg/kg respectively. The concentration of all understudy metals was below the Food and Agriculture Organization/World Health Organization (WHO/FAO) standards except for Co, in one sample. However, the concentration of heavy metals may increase, which may have profound repercussions. Therefore, preventive measures should be taken in this regard. The neutrosophic approach has been utilised to examine the variation of the heavy metals content in wheat leaves. This study provides a solid scientific foundation for future appropriate actions and management of heavy metals contamination in food crops near coal-fired power stations.

Effects of Processing on Nickel Content and its Relationship with Proximate Composition in dead fresh and canned tuna fish in Iran

Background: The presence of toxic metals in food can be a risk to food safety and public health. Methods: The Iranian canned tuna was analyzed for nickel level after wet digestion with acids using Graphite Furnace Atomic Absorption Spectrometry (GFAAS). Results: The average concentration of nickel in canned and dead fresh fish found 4.20 ppb and 1.64 ppb. A significant difference in nickel level was observed between canned and dead fresh fish samples in this study. Although the concentration of nickel per g in the fillet after processing was relatively low, but the total amount of nickel in the sample shown change (256.01%). The results in present study showed the protein content in the canned fish increased to 13.17%. The moisture content in the processed fish decreased to 8.80%. The fat content in the canned fish increased to 12.86%. Conclusion: Although the protein and moisture contents significantly increased and decreased respectively after processing, but none of these factors were related to the change in nickel concentration. It may be recommended to regularly monitor the concentration of nickel metal in aquatic food products, so that human health was not at risk.

The analysis of e-liquids: A study on chemical diversity and metal content using gas chromatography-mass spectrometry and inductively coupled plasma-mass spectrometry.

This work aimed to determine the chemical composition of 22 e-liquids available on the Slovenian market. Four different gas chromatography (GC) sample introduction techniques; headspace-GC-mass spectrometry (HS-GC-MS), liquid injection-GC-MS (LI-GC-MS), HS-solid-phase microextraction-GC-MS (HS-SPME-GC-MS), and direct-immersion-SPME-GC-MS (DI-SPME-GC-MS) were employed for qualitative analysis. Various experimental parameters were assessed for each GC sample introduction technique to maximize compound identification. Despite e-liquid packaging reporting a maximum of eight compounds, GC-MS identified more compounds in most samples, especially in menthol-flavored (58 identifiable compounds by HS-SPME-GC-MS), followed by nicotine-containing and fruit-flavored samples. HS-SPME-GC-MS identified the highest number of compounds, followed by HS-GC-MS, DI-SPME-GC-MS, and LI-GC-MS. Nicotine quantification in six samples was performed by LI-GC-MS with dilution in methanol. Nicotine concentration in samples ranged from 16.5±0.5 to 18.5±0.4 mg/mL, which was below the declared concentration of 20mg/mL. Additionally, quantitative analysis of metals in e-liquids was performed by inductively coupled plasma-MS after microwave-assisted wet acid digestion. Iron was the most abundant metal, with its content ranging from 0.024 to 0.354µg/g. Barium, bismuth, copper, and tin were also determined in several e-liquids.

High-solid digestion – A comparison of completely stirred and plug-flow reactor systems

High-solid digestion (HSD) for biogas production is a resource-efficient and sustainable method to treat organic wastes with high total solids content and obtain renewable energy and an organic fertiliser, using a lower dilution rate than in the more common wet digestion process. This study examined the effect of reactor type on the performance of an HSD process, comparing plug-flow (PFR) type reactors developed for continuous HSD processes, and completely stirred-tank reactors (CSTRs) commonly used for wet digestion. The HSD process was operated in thermophilic conditions (52 °C), with a mixture of household waste, garden waste and agricultural residues (total solids content 27–28 %). The PFRs showed slightly better performance, with higher specific methane production and nitrogen mineralisation than the CSTRs, while the reduction of volatile solids was the same in both reactor types. Results from 16S rRNA gene sequencing showed a significant difference in the microbial population, potentially related to large differences in stirring speed between the reactor types (1 rpm in PFRs and 70–150 rpm in CSTRs, respectively). The bacterial community was dominated by the genus Defluviitoga in the PFRs and order MBA03 in the CSTRs. For the archaeal community, there was a predominance of the genus Methanoculleus in the PFRs, and of the genera Methanosarcina and Methanothermobacter in the CSTRs. Despite these shifts in microbiology, the results showed that stable digestion of substrates with high total solids content can be achieved in both reactor types, indicating flexibility in the choice of technique for HSD processes.

An acidless microwave-assisted wet digestion of biological samples as a greener alternative: applications from COVID-19 monitoring to plant nanobiotechnology.

Sample preparation in an analytical sequence increases the number of errors, is highly time-consuming, and involves the manipulation of hazardous reagents. Therefore, when an improvement in an analytical method is required, the sample preparation step needs to be optimised or redesigned. Moreover, this step can involve significant toxic reagents and a high volume of waste. In that regard, this study proposes a new procedure based on microwave-assisted wet digestion combining two green strategies: a miniaturised system (with a few microlitres of volume) and the only use of hydrogen peroxide. Three biological samples (human serum, urine, and plant in vitro material) were chosen due to their high potential for disease monitoring, toxicological studies, and biotechnology applications. Several trace elements (Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni, Se, and Zn) were determined by inductively coupled plasma optical emission spectroscopy and inductively coupled plasma mass spectrometry. For human serum and urine, a certified reference material was used to check for accuracy; the recovery ranged from 72% (Cd, ICP-MS) to 105% (Mg, ICP OES) for serum, while for urine, they varied from 82% (Ni, ICP-MS) to 122% (Zn, ICP-MS). For the soybean callus sample (in vitro plant material), a comparison between the proposed method and the acid digestion method was conducted to evaluate the accuracy, and the results agreed. The detection limits were 0.001-60µg L-1 (lowest for Cd), thus demonstrating a suitable sensitivity. Moreover, the decomposition efficiency was demonstrated by determining the residual carbon, and a low amount was found in the final product digested (below 0.8% w v-1). A green metric approach was calculated for the proposed method, and according to AGREEprep software, it was found to be around 0.4. Finally, the method was applied to urine samples collected in patients with COVID-19 and soybean callus cultivated with silver nanoparticles. This sample preparation method is a new acidless and miniaturised alternative for elemental analysis involving biological samples.

Determination Ca, Cu, Fe, Mn, and Zn release from food in simple gastrointestinal extraction test

In this study, by conducting simulated in vitro digestion experiments on samples, the extraction rates of several essential metal elements in some common food ingredients were determined to guide a rational and balanced diet. At the same time, taking vegetables as an example, the research investigated the impact of food preprocessing on the extraction rates of metal elements within them, demonstrating that the influence of heat treatment varies for different element extraction rates. A wet digestion system using nitric acid-hydrogen peroxide was established for seafood and vegetable samples, and an analytical method for determining Ca, Cu, Fe, Mn and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) was developed. The detection limits of the method ranged from 0.0003 mg L−1 to 0.1567 mg L−1, with RSDs between 0.004% and 7.161%. The measured contents of several important metal elements in standard substances were largely consistent with national standards, confirming the accuracy and precision of the method. Based on wet digestion, the contents of various metal elements in simulated digestive fluids were determined. The detection limits for the simulated digestion method ranged from 0.0005 mg L−1 to 0.0077 mg L−1, with RSDs between 0.001% and 8.839%, verifying the precision of the method. Consequently, the extraction rates of metal elements in the two types of samples were obtained, leading to the conclusion that vegetable samples are more easily digested compared to seafood, releasing their metal elements. Moreover, the extraction rates of different elements vary within the same type of sample, and the extraction rates of the same element also differ across different samples. For dried fruit samples, a dry ashing digestion system was established, and an analytical method for determining Ca, Cu, Fe, Mn and Zn using ICP was developed. The detection limits of this method ranged from 0.0003 mg L−1 to 0.0073 mg L−1, with RSDs between 0.001% and 1.076%, and the spiked recovery rates were between 85.43% and 105.96%, confirming the accuracy and precision of the method. Based on dry ashing digestion, the contents of various metal elements in simulated digestive fluids were measured, which led to the determination of the element extraction rates. Among these, the extraction rates for Ca, Cu, and Mn were relatively high.

Determination of the levels of selected essential and toxic metals in soil collected from the flower farm in Roshara Roses PLC (Bishoftu) of Ethiopia and assessment of associated human health risks

The overuse of pesticides and fertilizers to grow high-quality roses unintentionally introduces heavy metals into the soil which is detrimental to the human health. Thus, the aim of the current study is to examine the concentrations of the essential (Ca, Mg, Zn, Fe, Cu, Fe, Mn and Ni) and toxic metals (Cd and Pb) in the soil samples from the flower farm using Flame atomic absorption spectrometry (FAAS) and to assess the risk that heavy metals pose to human health. To obtain an optimum condition for the wet digestion of soil samples, the volume ratio of reagents, reflux time and temperature were optimized. The concentrations of Ca, Fe, Mn, Mg, Zn, Cr, Ni, Cu were found to be 3468, 4926, 450, 255, 74, 70,48.5 and 25 and 2150, 4862,472, 241, 71, 58, 37 and 12.5 mg/kg for the soil samples collected from the flower farm and road side, respectively. Cadmium and lead were not detected in the studied soil samples. Statistical analysis of variance (ANOVA) showed the concentrations of Ca and Cu in the two soil samples are significantly different. Correlation analysis showed there was strong positive association for Fe with Zn, Cr and Ni, Mg with Ca, Cu, Ni and Cr, Zn with Cr and Cu and Ni with (Cu, Zn and Cr). Values of hazard quotient (HQ) and hazard index (HI) for the heavy metals under the study in the all exposure pathways are below 1.0 indicating that none of them could be harmful to human health.

Chemometrics, health and environmental risk assessments of commonly consumed biscuits in Lagos and Ibadan metropolises, Southwestern Nigeria

The United Nations' Agenda 2030 for sustainable development calls, amongst others, for universal action toward ending malnutrition and ensuring healthy living and well-being for all. So, efforts have intensified to attain the sustainable development goal-2 targets on stunting and wasting in children. Reported herein, therefore, is the quantification of metals in biscuits. Biscuits are commonly consumed snacks world-over and have become sources of nourishment for children and adults due to growing sedentary lifestyles and hectic school/work schedules. Nine metals (Pb, Ni, Cu, Co, Zn, Fe, Na, Mg and Ca) were assayed in six biscuit types (crackers, cookies, shortcakes, digestives, cabins and wafers) via wet digestion and flame atomic absorption spectrophotometry, and the ensuing data subjected to multivariate analyses (analysis of variance, Tukey's test, Pearson correlation, and principal component and hierarchical cluster analyses). The highest concentrations of macrominerals were found in the wafers (Ca), crackers (Na) and cabins (Mg) whereas the micronutrients peaked in the cookies (Fe, Zn), crackers (Cu), shortcake (Co) and wafers (Ni), respectively. The metal levels in the sampled biscuits were all safe for consumption, except for Pb at 0.83 ± 0.76–2.3 ± 1.3 mg/kg. Similarly, the health risk assessments of ingesting metals from the biscuits exposed Pb as potentially liable to cause adverse non-carcinogenic and carcinogenic health effects in children (aged 4–20 years) but Co and Ni exhibited borderline non-carcinogenic and carcinogenic health risks, respectively, in children. Gratifyingly, the ecological risk assessments to evaluate the likelihood of wastes, from expired and/or egested potentially toxic metals-contaminated biscuits, to cause damage to ecology were categorized as low. Nonetheless, constant evaluation and monitoring remain germane.

Bioaccumulation and Health Risk Assessment of Potentially Toxic Metals in Citrus Limetta & Citrus Sinensis Irrigated by Wastewater.

The aim of this study was to evaluate the impact of different irrigation sources on the levels of potentially toxic metals (Cd, Cr, Fe and Mn) in the edibles of citrus fruits (Citrus sinensis and Citrus limetta). The samples of fruit, soil and water were collected from two locations (fresh water irrigated-FW I and sewage water irrigated-SW II) within the city of Sargodha. The samples utilized in the study for metal analysis were prepared utilizing the wet acid digestion method. Metal determination was performed using Atomic Absorption Spectrometry (AAS). The potentially toxic metal values in the citrus samples ranged from 0.010 to 0.063, 0.015 to 0.293, 6.691 to 11.342 and 0.366 to 0.667mg/kg for Cd, Cr, Fe and Mn, respectively. Analysis of Citrus limetta and Citrus sinensis indicated that the highest concentration of Cr, Fe and Mn is observed at the sewage water irrigation site (SW-II), whilst the minimum levels of Cr, Fe and Mn were observed at the fresh water irrigation site (FW-I). The results show that the levels of these metals in soil and fruit samples meet the acceptable guidelines outlined by USEPA and WHO. It was found that the metal pollution constitutes a potential threat to human health due to the HRI values for Cd, Cr, and Fe being above 1, despite the DIM values being below 1. Regular monitoring of vegetables irrigated with wastewater is highly recommended in order to minimise health risks to individuals.

Comparison of Dry, Wet and Microwave Digestion Procedures for the Determination of Heavy Metal in Yoghurt Samples

Abstract: This work proposes a novel technique for utilizing the most suitable digestion process to determine concentrations of heavy metals such as Pb, Cd, Al, As, Zn, and Fe in Yoghurt samples using AAS. Conventional digestion techniques often involve time-consuming and tedious procedures, which leads to the loss of analyte and reduced accuracy. In this study, we propose the utilization of microwave-assisted digestion, a rapid and efficient technique that offers complete digestion of the samples and minimizes the risk of analyte loss. In order to get optimal efficiency and precision, this study outlines the optimization of the microwave-assisted digestion parameters, such as power, time, and reagent concentrations. The proposed method was validated by calculating the recovery % among dry, wet and microwave digestion methods. Results show that among all, the recovery percentage was found to be highest in the microwave digestion method.

Heavy metals concentrations of traditional herbs consumed in Northwestern zone of Nigeria and associated health risks on humans

Herbal drugs have gained much popularity as alternative medicine among residents of the northern part of Nigeria, taking advantage of abundant medicinal plants in the region. This study therefore investigated the levels of some selected heavy metals (Cd, Hg, Ni, Pb and Zn) in five identified herbal drugs sold in Andaza town, Kiyawa local Government area of Jigawa State. Preparation of the samples was done using a wet digestion method with HNO3 and HCl as digestion acids and the metals were determined using an atomic absorption spectrophotometer (AAS). The health risk assessment (HRA) for adults and children was done by using the estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and target cancer risk (TCR). The concentrations of heavy metals on dry weight (dw) basis in this study fell within the range (mg/kg dw, mean±SD)): Cd (0.156-0.312, 0.221±0.065), Hg (8.58-16.7, 12.7±3.78), Ni (0.960-2.74, 1.67±0.698), Zn (4.26-10.1, 6.17±2.34) and Pb (0.876-1.91). Pb was not detected in two out of the five samples and therefore the mean±SD of Pb was not computed. A comparison of the results with the World Health Organisation (WHO) maximum permissible limit showed that Hg levels were far above the permissible limit in all the samples; two samples had Cd values above the maximum limit. The concentrations of Ni, Zn and Pb in all the samples were within the recommended levels of WHO. Results of HRA showed that THQ were less than 1 in the analyzed metals except for Hg with relatively high values in both adults (70 kg body weight) and children (24 kg body weight) categories and this may pose a potential health risk to consumers. Results of the percentage non-carcinogenic risk (NCR) of each metal showed that Hg contributed more than 95% to HI (the overall NCR) in each sample. TCR of Pb indicates moderate to high cancer risk whereas, that of CD showed high to very high cancer risk if the samples are consumed for a long period of time. It is therefore important that consumption of these medicines should be monitored and regulated in order for consumers to avoid future health challenges.

Handheld In Situ Methods for Soil Organic Carbon Assessment

Soil organic carbon (SOC) assessment is crucial for evaluating soil health and supporting carbon sequestration efforts. Traditional methods like wet digestion and dry combustion are time-consuming and labor-intensive, necessitating the development of non-destructive, cost-efficient, and real-time in situ measurements. This review focuses on handheld in situ methodologies for SOC estimation, underscoring their practicality and reasonable accuracy. Spectroscopic techniques, like visible and near-infrared, mid-infrared, laser-induced breakdown spectroscopy, and inelastic neutron scattering each offer unique advantages. Preprocessing techniques, such as external parameter orthogonalization and standard normal variate, are employed to eliminate soil moisture content and particle size effects on SOC estimation. Calibration methods, like partial least squares regression and support vector machine, establish relationships between spectral reflectance, soil properties, and SOC. Among the 32 studies selected in this review, 14 exhibited a coefficient of determination (R2) of 0.80 or higher, indicating the potential for accurate SOC content estimation using in situ approaches. Each study meticulously adjusted factors such as spectral range, pretreatment method, and calibration model to improve the accuracy of SOC content, highlighting both the methodological diversity and a continuous pursuit of precision in direct field measurements. Continued research and validation are imperative to ensure accurate in situ SOC assessment across diverse environments. Thus, this review underscores the potential of handheld devices for in situ SOC estimation with good accuracy and leveraging factors that influence its precision. Crucial for optimizing carbon farming, these devices offer real-time soil measurements, empowering land managers to enhance carbon sequestration and promote sustainable land management across diverse agricultural landscapes.

Efficacy of chemical digestion methods to reveal undamaged microplastics from planktonic samples

Standardisation and validation of methods for microplastics research is essential. A major methodological challenge is the removal of planktonic organisms from marine water samples allowing for the identification of microplastics associated to planktonic communities. To improve the reproducibility and accuracy of digestion methods for the removal of planktonic biomass, we compared and modified existing chemical digestion methods. These digestion methods included an acidic digestion using nitric acid, alkaline digestions with potassium hydroxide (alkaline 1 digestion) and sodium hydroxide from drain cleaner (alkaline 2 digestion), an oxidative digestion using sodium dodecyl sulfate with hydrogen peroxide, and an enzymatic digestion using enzyme drain clean pellets. Chemical digestion of three densities of zooplankton communities (high, medium, and low) in the presence of five commonly found environmental microplastic pollutants (polyamide, polyethylene, polyethylene terephthalate, polypropylene, and polystyrene) were performed for each treatment. The chemical treatments were assessed for (i) their digestion efficiency of zooplankton communities by different biomass densities, and (ii) their impact on microplastic particles through the comparison of both chemical (Raman spectroscopy) and physical (length, width, and visual) changes, between the pre-treatment and post-treatment microplastic particles. The alkaline 1, alkaline 2 and oxidative methods demonstrated significantly better digestion efficiency (p < 0.05) than the modified enzymatic and acidic treatments. The acidic, alkaline 1, and alkaline 2, treatments caused the most damages to the microplastic particles. We suggest future studies to implement the oxidative digestion method with sodium dodecyl sulfate and hydrogen peroxide because of its high digestion efficiency, and low damage to microplastic particles. This method is similar to the wet peroxide oxidation digestion method used throughout the literature but can be implemented at a lower cost.

The Determination of Minerals in Soil, Water, Fodder, and Serum and their Effects on Reproductive Efficiency of Nili Ravi Buffaloes

Introduction: Minerals play an essential role in the reproductive performance of dairy animals, especially in buffaloes. The present study aimed to evaluate the mineral concentrations in different types of samples, including soil used for fodder cultivation, canal water used for fodder irrigation, drinking water for buffaloes, fodder used for buffalo feeding, and serum of buffaloes and their effects on the reproductive efficiency of buffaloes. Materials and methods: The current study was carried out for three months and samples were analyzed twice at the beginning and the end of the study. The concentrations of calcium, magnesium, and inorganic phosphorus in the soil were checked through the versinate method. The concentration of calcium, magnesium, and inorganic phosphorus in water was checked through the titration method and the concentration of calcium, magnesium, and inorganic phosphorus contents in fodder was checked through the wet digestion method. The minerals of blood serum (n = 80) were analyzed through commercial kits. Results: In canal water, calcium concentration was higher for irrigation compared to buffalo drinking water. Similarly, on the upper surface of the soil compared to its low surface, the level of calcium was high. Calcium values of serum were higher in cyclic buffaloes compared to buffalo heifers. In comparison to all groups, the levels of inorganic phosphorus were found to be lower in non-cyclic buffaloes. Similarly, the calcium-to-phosphorus ratio was found to be lower in non-cyclic buffaloes and heifers compared to repeat breeders and cyclic buffaloes. At the beginning of the study, cyclic buffaloes had higher magnesium levels than all other groups, except for non-cyclic buffaloes. By the end of the study, magnesium concentrations were higher in non-cyclic buffaloes and heifers compared to repeat breeders and cyclic buffaloes. Conclusion: The mineral deficiencies in water and soil can affect the fodder content in the feed of buffaloes.

Performance, interaction, and metabolic pathway of novel dry–wet anaerobic digestion for treating high-solid agricultural waste

Anaerobic digestion (AD) with high-solid content of agricultural waste often leads to the accumulation of volatile fatty acids (VFAs) due to the imbalance of the functions of hydrolytic acidification bacteria and methanogenic archaea. This study developed a novel dry–wet AD of high-solid content was developed to make acidogenic bacteria and methanogenic archaea having higher collaboration ability. The results showed that the dry–wet AD system achieved a dynamic balance and synergistic effect between hydrolytic acidification and the methane production process, which shortened the lag phase to a minimum of 1.21 days. Additionally, the system exhibited a highest volumetric biogas production rate of 1.76 L L−1 d−1 when CM:CS and the initial pH were 6:4, 8.0, respectively. The total VFA concentration reached a maximum of 4.69 g L−1 d−1 and acetic acid (HAc) and butyric acid (HBu) were dominant VFAs (88.75%–93.27%) in the leachate in hydrolytic acidification phase. Metagenomic analysis indicated Pseudomonadales, Clostridiales, Bacteroidales, Spirochaetales, and Methanosaeta were dominant microorganism in hydrolytic acidification phase and methanogenic phase, respectively. The gene abundance of key enzymes in the acetoclastic methanogenic pathway significantly exceeded that of the hydrotrophic methanogenic pathway. This study provides a novel AD technology and insights into the energy conversion of agricultural waste.

Determination of chemical elements of barley and teff using flame atomic absorption spectroscopy (FAAS)

Metallic elemental analyses are needed to complete food composition databases, in which humans consume food to obtain energy and be able to do everyday work. The study aimed to investigate the concentrations of some metals (K, Al, Fe, Cu, Cd, and Pb) in teff and barley samples using flame atomic absorption spectroscopy (FAAS) techniques. The samples, weighing 0.5 grams each, were subjected to wet digestions using a mixture ratio of 7:3(vol/vol) of HNO3 to H2O2 reagents at 90°c for 3:00 h under optimal conditions. The reagents were used to digest food samples for the presence of specific metallic elements. Flame Atomic Absorption Spectroscopy (FAAS) was used to analyze the mineral contents of the digested samples. The results demonstrated that the relative concentrations obtained in these cereal crops are different from one another. The concentration of metallic elements in mg/kg of K (2709.6±3.3), Al (952.3±4.2), Fe (320.9±4.8), Cu (25.3±3.2), Pb (ND) and Cd (ND) for red teff, K (3053.7±1.6), Al (1095.2±4.2), Fe (271.6±4.8), Cu (60.1±3.2), Pb (ND) and Cd (ND) for white teff while K (4333.3±3.2), Al (2595.2±4.2), Fe (74.0±0.00), Cu (10.5±1.8), Pb (ND) and Cd (ND) for barley. The high content of potassium and aluminum metallic elements was found in barley cereals. The results of this study will be useful in enriching the database of Ethiopian cereals as foods, advancing the knowledge of cereals and deepening the scientific understanding of the cereals.