Vegetable Residues Research Articles

Pesticide residues in fruits and vegetables: Analysis and risk assessment of EU RASFF notifications between 1999 and 2022

Pesticides are commonly used to increase agricultural productivity by decreasing pest damage to crops. However, their residues may have detrimental consequences on human health. The Rapid Alert System for Food and Feed (RASFF) pesticide notifications in fruits and vegetables (F&V) were analyzed over the past 24 years to identify the most frequently reported products, pesticides, their origin countries, and their associated potential risks. The F&V product category received 5040 pesticide residue notifications, accounting for 67.1 % of total notifications related to pesticide residues across all product categories. Bulgaria and Germany were the major notifiers, while Turkey and India were the most notified origin countries of these notifications. 52.3 % of the total notifications were classified as border rejection. The top notified pesticides were chlorpyrifos (13.3 %), dimethoate (6.5 %), carbendazim (5.2 %), chlorpyrifos-methyl (5.1 %), and omethoate (4.7 %), while the top notified products were sweet peppers (22.4 %), beans (7.6 %), okra (5.1 %), oranges (4.6 %), and grapes (4.2 %). Critical associations between specific pesticides and produce highlight grave health concerns, notably with dichlorvos in beans and amitraz in pears, surpassing acceptable limits and posing potential health hazards. The study underscores the importance of proactive risk management actions such as destruction and withdrawal in addressing these concerns for consumer safety in addition to more multi-control risk management actions.

A smartphone-assisted portable on-site detection system for organophosphorus pesticides in vegetables and fruits based on all-in-one paper-based sensors: 2,2-Dichlorovinyl dimethyl phosphate as a model

The improper use of organophosphate pesticides (OPs) can lead to residue posing a serious threat to human health and environment. Therefore, the development of a simple, portable, and sensitive detection method is crucial. Herein, a bioenzyme-nanozyme-chromogen all-in-one paper-based sensor was synthesized. Initially, the Ce/Zr-MOF with peroxidase-like activity was grown on filter paper (FP) using in-situ solvent thermal method, resulting in Ce/Zr-MOF@FP. Subsequently, the AChE-ChO-TMB system was immobilized onto Ce/Zr-MOF@FP using biocompatible gelatin, which enhanced cascade catalysis efficiency through the proximity effect. Based on the inhibition principle of OPs on AChE, we integrated this sensor with Python-based image recognition algorithm to achieve detection of OPs. Using 2,2-dichlorovinyl dimethyl phosphate (DDVP) as a model of OPs, it has good detection performance with a detection limit of 0.32 ng mL−1 and a recovery rate range of 95–107%. The potential for on-site detection of DDVP residues in vegetables and fruit samples is highly promising.

Soil hydro-physical variables and crop residues determinate runoff, soil loss, and glyphosate and AMPA concentration in the aqueous phase under simulated rainfall events.

Soil structural degradation and water erosion processes were observed even in no-tillage schemes in the Pampas region. Within these conservation systems, agrochemical application per hectare is one of the highest globally. Thus, this entails a serious risk of water contamination. The objectives of this study were to (1) test the hypothesis that the hydrological dynamics and sediment concentration related to surface runoff were conditioned by soil structure regardless of the presence of maize (Zea mays L.) crop residue and (2) assess the incidence of maize crop residue on glyphosate and aminomethylphosphonic acid (AMPA) concentration in runoff. The soil under study corresponded to Arroyo Dulce Series (Typic Argiudoll silty loam soil). Rain simulations were performed in the laboratory on undisturbed soil samples. Total runoff and infiltration rate were similar between treatments with C(+) and without C(-) maize crop residues (C(+) 1381.40mL and 14.27mm h-1, C(-): 1529.70mL and 21.67mm h-1). The C(-) treatments showed a higher sediment concentration than C(+) (1.58 and 0.42g 100mL-1, respectively). Glyphosate and AMPA average values in runoff were 15.9 and 33.9µg L-1. High variability of the hydro-physical properties and occurrence of soil structure, particularly platy ones, were detected. The hydrological variables were conditioned mainly by the occurrence of platy structures regardless of crop residue presence. Glyphosate concentration was increased in the first runoff event by the presence of corn residues, while AMPA concentrations were higher in the second runoff event in both residue treatments. In this study, maize residue on the soil surface protected the soil from sediment detachment but did not change runoff or infiltration. Thus, the implementation of agricultural management practices that promote vegetative residue cover has shown positive results to erosion.

Removal of pesticide residues from vegetables by hydrogen peroxide assisted ultrasonic process

This study addresses the concern of pesticide residues in vegetables by exploring the hydrogen peroxide assisted ultrasonic (H2O2/US) process for the removal of six pesticides from pakchoi, a popular green vegetable in China. Remarkably high efficiency was achieved, with removal rates reaching 83.9%, 68.8%, 85.9%, 91.6%, 75.6%, and 73.4% for dimethoate, dichlorvos, methiocarb, propoxur, chlorobenzuron, and etridiazole, respectively, through the H2O2/US process. A notable synergy was observed in the coupled H2O2/US process. The analysis of mass balance and degradation pathways indicates that the synergy stemmed from the efficient oxidation of pesticides by hydroxyl radicals (HO•) formed via sonolysis of H2O2. Surface properties of vegetables showed great impacts on pesticide removal by H2O2/US. Despite these treatments, the H2O2/US process exhibited minimal impact on vegetable quality. Overall, this study underscores the potential of the H2O2/US process as a promising technology for effectively removing pesticides from vegetables.

Pesticide residues in vegetables from Gansu province, China and risk assessment by Monte Carlo simulation

ABSTRACT To assess the dietary exposure risks of pesticide residues in vegetables for the general population, the presence of 39 pesticides was determined in 70 samples, of which 13 were detected. The most frequently detected pesticide was bifenthrin, with a detection rate of 35.7%, mainly found in gingers, followed by isoprocarb and acephate (11.4%) and dimethoate (8.6%). In 17.1% of the samples two or more pesticide residues were found. Acute, chronic and chronic cumulative dietary exposure risk was assessed. Chronic exposure risks were determined by Monte Carlo Simulation (MCS). Estimated chronic exposure to carbofuran, omethoate, disulfoton and dimethoate of approximately 49%, 52%, 40% and 3%, respectively, were at non-carcinogenic human risk. Acute exposure risk to acephate was considered to be of concern due to the high acute hazard quotient (aHQ).

Pesticides in vegetables and fruits from Brazil and risk assessment

ABSTRACT Levels of 237 pesticides were assessed in 1063 fruit and vegetable samples from 12 São Paulo markets spanning the period May 2015 to December 2022. The QuEChERS method was employed for extraction, followed by GC-MS/MS and LC-MS/MS analysis. Findings indicated that 30% of the samples contained residues below the Maximum Residue Limits (MRLs), while 6% exceeded these. Additionally, 23% exhibited excessive residues for their respective crops and 40% had no detectable residues. Health risk evaluation focused on tomatoes, cabbage and oranges, revealing exposure within 0.002–0.9% of the Acceptable Daily Intake (ADI), indicating no chronic risks. However, pyraclostrobin in orange presented a potential acute risk for adults (112%). These results underscore the necessity for continuous monitoring of pesticide residues in fruits and vegetables to safeguard consumer health, especially considering the significant levels of consumption.

Assessment of Two Extraction Methods LLE and QUEChERS to Determine Pesticides Residues in Vegetables by Gas Chromatography

Assessment of Two Extraction Methods LLE and QUEChERS to Determine Pesticides Residues in Vegetables by Gas Chromatography

Evaluation and implications of organophosphate pesticide residues in cabbage (Brassicaoleracea)

The improper application of pesticides in cultivating vegetables has resulted in the buildup of pesticide residues on vegetables. This study evaluated organophosphate pesticide residue levels in cabbage with specific objectives of investigating the varieties of organophosphate pesticides employed by farmers and their awareness, assessing residue levels on cabbage using semi-structured questionnaires, and determining the distribution of pesticide residues within the layers of the cabbage head using 50 cabbage samples randomly collected from farmers from 14 cabbage-producing communities. The findings indicated that 98 % of the farmers applied pesticides in the morning, whereas 24 % preferred evening application. Meanwhile, 22 % applied pesticides twice in a day. Also, 18 % combined pesticides, 40 % applied 20 ml during the application, 72 % chose a particular pesticide based on the expected efficiency, 46 % applied pesticides between 1 and 5 times in a season and 66 % sprayed between 7 and 14 days. Pyrinex 48 EC and Perferthion emerged as the predominant organophosphates, with usage rates of 10 % and 12 % respectively. Also, eleven (11) organophosphate pesticide residues were identified in the cabbage samples. Profenofos and chlorpyrifos exhibited the highest concentrations of pesticide residues, with levels reaching 0.02 mg/kg, with 56.6 % of the samples containing chlorpyrifos pesticide residue. Nevertheless, all the identified pesticide residues did not exceed the maximum residue limits for cabbage. The study analysis disclosed the presence of various organophosphate pesticide residues in the first 10 layers of cabbage. However, it was noted that the innermost layers might not contain any detectable pesticide residues. The findings highlight the need for farmers to use pesticides judiciously and follow recommended application practices to minimize vegetable residues.

PEMANFAATAN EKOENZIM DARI KULIT BUAH-SAYUR UNTUK PENINGKATAN KUALITAS AIR DANAU BATUR DI KECAMATAN KINTAMANI BANGLI, BALI

Eco enzyme production through the fermentation process of household waste, such as leftover fruit and vegetables can also be a solution to minimize waste from its source. This research aims to determine the effect of a mixture of organic materials, fruit and vegetable waste eco enzyme on pH, and the effect of eco enzyme dosage on improving the water quality of Lake Batur, Kintamani Bali. Making eco enzymes using vegetable and fruit waste. water, molasses in a ratio of 3: 10: 1. The liquid is fermented for 3 months while observing the fermentation process. Eco enzyme is harvested and filtered, ready for testing to improve the water quality of Lake Batur. The results of observations of making eco enzyme can be explained that in the first 4 weeks, there was a change in colour with shades of brown to reddish, after the fourth week the colour was relatively stable (no colour change. Changes in pH during the process of making eco enzymes were related to variations in the composition of organic material (vegetable residues. There was a decrease in pH). with an average of up to 1 digit, the highest reduction occurred in ingredients containing papaya, mango and mustard greens. Eco enzymes can improve water quality as indicated by several water quality parameters, but are not enough to achieve conformity with the established quality standards. Keyword: Eco Enzyme; Water Quality; Batur Lake

Stable detection of diazinon residues in vegetables by an electrochemiluminescent aptasensor based on the in-situ production of H2O2 from dual-catalytic glucose

Stable detection of diazinon (DZN) residues in vegetables is important for food safety. In this work, an electrochemiluminescence (ECL) aptasensor with dual-catalytic glucose in-situ production of H2O2 was constructed for the stable detection of DZN in vegetables. Firstly, MWCNTs@MB was prepared using π-π stacking interactions between methylene blue (MB) and multi-walled carbon nanotubes (MWCNTs) to enhance the loading of MB on an electrode and thus catalyze the generation of H2O2 from glucose. Secondly, Cu2O@AuNPs was formed by loading AuNPs on the surface of Cu2O through spontaneous reduction reaction, which improved the interfacial charge transfer, Cu2O nano-enzyme had glucose oxidase mimicking activity and could further catalyze the production of more H2O2 from glucose. MWCNTs@MB and Cu2O@AuNPs played a key role in the in-situ generation of co-reacting reagent H2O2, which solved the problem of unstable detection caused by the easy decomposition of the H2O2 solution added to the luminescence system. In addition, the aptamer was immobilized on the electrode surface by forming Au–S bonds with Cu2O@AuNPs. As a result, the ECL aptasensor performed good linearity in 1.00 pg mL−1-1.00 μg mL−1 and a low limit of detection (LOD) to 0.39 pg mL−1 (S/N = 3). This work provided an effective method for the accurate and stable detection of DZN residues in vegetables, which was of great significance in ensuring food safety and assessing the environmental risk of DZN.

Bacillus cereus GW-01 inoculation reduces pyrethroid residues and improves quality of Sichuan Paocai by changing the metabolic profile of fermentation

Pyrethroid residues in vegetables pose a challenge for household food processing. This study introduced Bacillus cereus GW-01, a pyrethroid-degrading bacterium, into Sichuan Paocai (SCP) fermentation. The study investigated the reduction of β-cypermethrin (β-CY), fenpropathrin (FNP), and λ-cyhalothrin (LCT) residues, alterations in metabolic profiles, and shifts in bacterial communities. Over fermentation, concentrations of β-CY, FNP, and LCT decreased. Notably, compared to the control, GW-01 proliferated in SCP, and the sample with GW-01 exhibited an enhanced degradation of β-CY, FNP, and LCT by 26.14%, 36.32%, and 33.70%, respectively. GW-01 presence lead to significant increases in volatile flavor components (VFC), organic acids (OA) including tartaric acid and succinic acid, and free amino acids (FAA) including Asn, Glu, Lys, and Pro after 7 days. The relative abundance of Bacillus in the group inoculated with GW-01 was higher than control, and the probiotics including Leuconostoc, Latilactobacillus, Brochothrix, Weissella, Lactobacillus, and Lactococcus, experienced a remarkable upsurge, reaching their zenith on the 7th day. Compared to CK, intriguing pathways such as bacterial chemotaxis, benzoic acid family, and mineral adsorption were additionally enriched in groups exposed to GW-01 and pyrethroids. The study's aim is to provide insights for reducing pesticide residues and enhancing fermented food quality.

Development of an organophosphate and carbamate pesticide test kit by using a magnetic particle coated with esterase enzyme from honey bee heads

Organophosphates (OPs) and carbamates (CMs) play a vital role in Thai agriculture, public health, and pest control. However, their detection presents challenges due to expensive methods requiring specialized expertise. Addressing this gap, our study introduces an innovative, cost-effective method for detecting OPs and CMs in Thailand. We utilized the test kit by using magnetic particles coated with esterase enzymes from honey bee heads combined with a colorimetric approach. The developed test kit shows low limits of detection (LODs) at 0.001 mg/L of dichlorvos (OPs) and 0.004 mg/L for carbaryl (CMs). The efficiency of the developed test kits in comparison with the standard technique of gas chromatography with flame photometry detection (GC-FPD) shows a comparable result in fruit and vegetable residue analysis. This developed test kit proposes a cost-effective OPs and CMs analysis test kit for Thailand, promising expense reduction and simplified verification processes. Its applicability to fruits and vegetables signifies practicality in agriculture, marking a significant advancement in accessible and efficient pesticide residue monitoring. Despite challenges in pesticide use, our method holds promise for improving safety and efficiency in Thai pesticide management.Graphical

Impact of Plant Extracts on the Pollination Activity of <i>Apis mellifera</i> Linnaeus, 1758 (Hymenoptera: Apidae) on Flowers of Cowpea Variety Feekem, in Dang (Adamaoua, Cameroon)

Synthetic pesticides present worldwide risks of contamination of humans, livestock and the environment due to the strong persistence and the toxic residues in fruits and vegetables. Natural biopesticides of local plant origin present low persistence and are the best alternative for the control of crop pests. In the Adamaoua region (Northern Cameroon), few studies exist concerning effects of botanical pesticides on the behavior of beneficial insects. Studies aimed to draw up a list of pollinating insects on flowers of <i>Vigna unguiculata </i>(L.) Walp., 1843 (Fabales: Fabaceae), in situations of treatment with botanical pesticides compared to the situation of the use of synthetic insecticide and to determine the effect of the biopesticides on the behavior of the main floricultural insects. Field investigations were carried out during two cowpea cultivation campaigns (June to September 2021 and June to October 2022) in Dang (suburb of Ngaoundere) on the effect of leaves extracts of local plant origin on the foraging behavior of <i>Apis mellifera</i> Linnaeus, 1758 (Hymenoptera: Apidae) and the main sap-sucking insect <i>Aphis craccivora </i>Koch, 1854 (Hemiptera: Aphididae). Forty-four cowpea plots of 4x3.5 m each distributed according to the randomized complete block model (four untreated plots as negative control, four plots treated with the synthetic insecticide Parastar (40EC 535/ 10/IN, 20 g/l of imidacloprid and 20 g/l of lamda-cyhalothrin) as positive control, and 36 experimental plots treated with three concentrations (10%, 20% and 30%) of aqueous leaves extract of <i>Calotropis procera</i> (Gentianales: Apocynaceae), <i>Eucalyptus camaldulensis </i>(Myrtales: Myrtaceae), and <i>Tithonia diversifolia</i> (Asterales: Asteraceae) respectively, made it possible to conduct four treatments: (1) flowers left to freely pollination, (2) flowers protected against pollinators, (3) flowers visited exclusively by <i>Ap. mellifera</i> and (4) flowers protected against insects. Among eight species (four orders, four families and seven genera) recorded on the flowers of <i>V. unguiculata</i>, the domestic bee <i>Ap. mellifera</i> was the most common and collected nectar and pollen. The control plots and those treated with 10% or 20% aqueous leaves extracts allowed the bee to carry out its activity. Plots treated with 30% extract of each plant and those treated with the synthetic insecticide Parastar, drastically altered the rhythm and speed of activity in <i>Ap. mellifera</i> foragers. This behavior became less coordinated and slow on treated plants. It would be wise to use 10% or 20% aqueous extracts as botanical insecticides and an alternative to the synthetic insecticide Parastar.

Consumer Awareness and Perceptions of Pesticide Residues in Vegetables in Bangladesh

Vegetables are heavily sprayed and prone to retaining residues. The Department of Agriculture Extension (DAE), Bangladesh has set up some projects to disseminate technologies among the farmers to reduce pesticide residues. Farmers are motivated to produce pesticide-free vegetables using vermin compost and other organic fertilizers. The study investigates consumers’ awareness and perceptions of pesticide residues in vegetables. A survey was conducted at the local market in Mymensingh, Gazipur, and Dhaka city. In total. 200 sample respondents were collected. Data were analyzed using descriptive methods. There was a substantial heterogeneity in preferences across consumers. The consumers were aware of the health risks associated with vegetables produced using pesticides and chemical fertilizers. More than 60 percent of respondents thought that vegetables are usually contaminated at the farm or production level using excessive pesticides. Most of the consumers knew the effects of pesticide-borne health risks and suggested to ban some pesticides and monitoring the use of others. Consumers considered pesticide residue-free vegetables as being safer, healthy, no harmful effects, better taste, more nutritive value, and good for the environment, and would like to pay a premium for those products. Media particularly television and newspapers can play an important role in creating awareness about food safety among the producers and consumers. Government programmes on food safety should be channeled through television and newspapers where the majority of the people get their information. Policy measures should include creating awareness concerning the relevance of production, and consumption through effective marketing strategies and educational awareness. Res. Agric. Livest. Fish. Vol. 11, No. 1, April 2024: 25-33

Gold nanoparticle-mediated molecularly imprinted electrochemical sensor MIP/AuNPs/GCE for highly sensitive and selective detection of neutral phosmet residues in fruits and vegetables

A novel electrochemical sensor MIP/AuNPs/GCE was developed by depositing gold nanoparticles and electropolymerizing molecularly imprinted film on the surface of glassy carbon electrode (GCE) for highly sensitive detection of neutral phosmet residues in fruits and vegetables. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the imprinted sensor. The results showed that the imprinted film on GCE was evenly prepared with better specific recognition of phosmet on MIP/AuNPs/GCE than that on bare GCE. Several parameters including deposition time, functional monomer and its molar ratio, scanning cycles, and elution time were optimized in detail. The linear range of the MIP/AuNPs/GCE prepared in this work was 0.020–4.0 nmol/L with limit of detection of 0.010 nmol/L, which was much lower than MIP/GCE (0.17 nmol/L). The identification mechanism of MIP/AuNPs/GCE for phosmet was also confirmed as adsorption-diffusion model with effective surface area increasing after mediated by AuNPs. Selectivity, reproducibility and repeatability of the MIP/AuNPs/GCE were acceptable. The recovery of applying the sensor to detect PM in real samples ranged from 91.40 % to 107.3 %, which agreed well with those of HPLC. The method of developing MIP/AuNPs/GCE sensor herein could be extended to detecting other neutral pesticide residues in food and environment.

Research on Development and Characterization of Composite Membranes Based on Hybrid Bacterial Cellulose Combined with Glycerol and Vegetable Residues for the Preservation of Fresh Fruit and Food

This study aims to develop a biocompatible and bioactive food-packaging composite film material. The material is based on bacterial cellulose (BC) microfibers from coconut jelly biomass combined with olive oil as a carrier of antibacterial properties. A composite membrane was fabricated with 20%, 30%, and 40 wt % glycerol and separately impregnated with 1%, 2%, and 3 wt % olive oil in the presence of BC. The results of SEM image structure and morphology show that the membrane was successfully fabricated with uniform distribution of BC, without losing its natural structure. The film was initially applied to preserve apples, and the research results showed that the mass index did not change significantly (ranging from 1.13 to 5.1 g); the hardness through the bearing test results showed a decrease. The preservation time of the composite membranes, which are based on bacterial cellulose combined with glycerol and vegetable residues, extends up to 20 days. The membrane with the highest concentration of vitamin C is soaked in BC/glycerol 30%/olive oil 2% membrane and the lowest is soaked in BC membrane.

Optimization of QuEChERS method for determination of pesticide residues in vegetables and health risk assessment.

The present study focused on the optimization of the QuEChERS extraction method for the determination of 61 pesticide residues and associated health risk assessment in 144 samples of commonly consumed vegetables, viz., eggplant, cabbage, green chilli, okra, and tomato. The samples were collected between January and April 2022 from three different districts within Gujarat, India. The QuEChERS method was optimized and utilized for the extraction of samples. The samples were analyzed by UHPLC-q-TOF/MS and GC-MS/MS. The modified QuEChERS method was successfully validated, and the obtained results were satisfactory as per the 2021 SANTE guidelines. The residue analysis of the vegetable samples showed that about 4% of total samples contained single pesticide residues. Pesticide residues below the quantitation limit (BQL) were observed in eggplant, cabbage, and okra samples. In total, 15.62% (n = 5) samples of green chilli showed the presence of pesticides such as azoxystrobin, bifenthrin, cypermethrin, fenpropathrin, and propargite whereas 3% (n = 1) tomato samples contained cyfluthrin. In total, 97.22% of the samples had residues that were below the European Union Maximum Residue Limit (EU MRL). Two samples of green chilli had pesticide residues above EU MRL. The Hazard Index (HI) and Hazard Quotient (HQ) were used to assess the health risks associated with green chilli and tomato consumption. The HI and HQ values for adolescents and adults were found to be less than 1. The modified QuEChERS method was found to be easy and effective and can be implemented for routine sample analysis. The study revealed the presence of pesticide residues in tomato and green chilli samples. Further, the outcome provided information pertaining to current pesticide status, concluding that consumption of these commodities is unlikely to pose any health risk, though long-term monitoring studies focusing on dietary health risk assessment must be initiated.

Nutrient Contribution and Carbon Sequestration of an Agroforestry System of Coffea canephora Cultivated by Conventional and Organic Management in the Ecuadorian Amazon

Agroforestry systems (AFSs) seek synergies that improve productivity, sustainability, and environmental benefits. This is achieved through the supplying of nutrients to the soil, carbon storage, and sequestration. In the Ecuadorian Amazon, Coffea canephora is planted together with leguminous, woody, forest, and secondary forest species, where the continuous incorporation of vegetative residues from shade species represents a substantial addition of nutrients within these systems. This study was carried out from 2018 to 2022 to determine the contribution of nutrients contained in the biomass and C sequestration in agroforestry systems of coffee with conventional (high use of agrochemicals) and organic (without the use of chemicals) management. The study was carried out with a randomized complete block design, using a factorial arrangement (2 × 4 with three replications). This arrangement included two types of systems (agroforestry and monoculture) and four agronomic management practices (high and medium for conventional, and intensive and low organic). The biomass and nutrient content were measured twice a year (every 180 days); in addition, the yield was also recorded. A multivariate and univariate analysis was used for data analysis through R and SAS software. After five years of evaluation, it was determined that the N, K, Ca, and Mg contents were higher in the agroforestry systems than the monocultures. In the AFSs, the highest nutrient content was obtained with the medium conventional and low organic agronomic management, while in the monocultures, it was obtained with the high and medium conventional management. In addition, at a soil depth of 20 cm, the total storage and CO2 were 38.12 and 139.8 t ha−1, respectively. The highest yields were obtained with conventional management in AFSs (1599 kg ha−1) and monoculture (1789.45 kg ha−1). Overall, AFSs showed a significant contribution of nutrients, such as N, K, Ca, and Mg, for coffee cultivation; moreover, yields were similar in the AFS and monoculture with both conventional and organic management, which is positive, since AFSs also contribute environmental benefits.

Development of Ozone Generator Mini with DDBD (Double Dielectric Barrier Discharge) Technology at Atmospheric Air Pressure

<p class="Abstract">Pesticide residues in fruits and vegetables pose a danger to human health if consumed for a certain period. This requires appropriate technology for household scale and is environmentally friendly. Ozone is a strong oxidizing agent capable of degrading pesticide residues in fruits and vegetables. Ozone is a green chemical compound because it does not produce harmful derivative compounds, and is even friendly to the environment. The development of a mini ozone generator with DBD technology has been successfully carried out. The DDBD reactor is made of Pyrex glass with a length of 10 cm and an outer diameter of 4 cm. The reactor uses electrodes made of copper plates. The outer electrode is 13 cm long and 5 cm wide, while the inner electrode is 10 cm long and 5 cm wide. Optimization of the mini ozone generator is carried out using high voltage AC pulses whose pulse frequency can be varied from 30 to 60 Hz with 10 Hz intervals. The free air flow rate was varied at 0.2 – 0.8 lpm with an interval of 0.2 lpm. The optimum ozone production of 480 mg/l was obtained at a voltage setting of 2.8 kV and a frequency of 50 Hz and a flow rate of 0.2 lpm. In this setting, the DDBD reactor consumes 9.32 watts of power. The development of mini ozone generator technology has the potential to be applied on a household scale because of the small reactor size and low power consumption. </p>

The Biogas Production Potential and Community Structure Characteristics of the Co-Digestion of Dairy Manure and Tomato Residues

Anaerobic digestion is an important means to turn agricultural waste into resources and an important way to address the challenges in treating vegetable residues in China. In this study, the co-digestion of dairy manure with tomato residue was investigated to clarify the effect of the total solids (TS) of the digestion substrate on methane’s production and mechanism using the self-made anaerobic digestion device. The results showed that all treatments could rapidly ferment methane and that the daily methane production showed a trend of increasing first and then decreasing. The optimal concentrations of the digestion substrate for liquid anaerobic digestion (L-AD), hemi-solid-state anaerobic digestion (HSS-AD), and solid-state anaerobic digestion (SS-AD) were 10%, 18%, and 25%, respectively. Compared with SS-AD and HSS-AD, L-AD gas production peaked 3–6 days earlier. Treatment TS25 had the best cumulative methane production, reaching 117.4 mL/g VS. However, treatment TS6 had acid accumulation and a very unstable system. The cumulative methane production of SS-AD was higher than that of HSS-AD and L-AD. Firmicutes and Bacteroidetes were the dominant flora, and Methanoculleus, Methanosarcina, and Methanobrevibacter were the main archaeal groups. The TS significantly changed the microbial community composition of the digestion system, especially the low TS treatment. The results presented herein indicated that TS significantly changed the bacterial and archaeal community composition of the digestion system, and thus with the increase in TS from 6% to 25%, the methane yield increased.