Biomonitoring of genotoxicity of industrial wastes using plant bioassays

Vicia faba seed: a bioindicator of phytotoxicity, genotoxicity, and cytotoxicity of light crude oil

Crude oil contamination is a serious threat to the environment and human health as it can contaminate food chains. Therefore, it is necessary to find efficient tests to monitor soils for crude oil contamination. The present study investigates the efficacy of Vicia faba seeds for monitoring contaminated soils with light crude oil. Vicia faba seeds were planted in 0 (control), 1, 2, and 4 percentages (weight percentage) light crude oil-contaminated soils. The seed germination and root length were measured to evaluate phytotoxicity, while the mitotic index, chromosome aberrations, and micronucleus formation in the root tip cells were examined for cytotoxicity and genotoxicity tests. The results showed that light crude oil had toxic effects on Vicia faba growth characteristics, even at 1% contamination. The phytotoxicity assay showed that crude oil reduced seed germination and root length by 45% and 61.67%, respectively. In contrast, cellular observations indicated an increase in mitotic index, chromosome aberrations, and micronucleus formation up to 3, 3.59, and 5.6 times, respectively, compared to the control. The light crude oil at 4% induced the simultaneous occurrence of nuclear bud, polyploidy, and micronucleus that may be considered as severe clastogenic and aneugenic effects. Accordingly, Vicia faba can be considered a reliable living system for monitoring light crude oil pollution in soils, even at low concentrations.

Vermiremediation of allopathic pharmaceutical industry sludge amended with cattle dung employing Eisenia fetida

The present study aims to vermiremediate allopathic pharmaceutical industry sludge (AS) amended with cattle dung (CD), in different feed mixtures (AS:CD) i.e (AS₀) 0:100 [Positive control], (AS₂₅) 25:75, (AS₅₀) 50:50, (AS₇₅) 75:25 and (AS₁₀₀) 100:0 [Negative Control] for 180 days using earthworm Eisenia fetida. The earthworms could thrive and grow well up to the AS₇₅ feed mixture. In the final vermicompost, there were significant decreases in electrical conductivity (29.18-18.70%), total organic carbon (47.48-22.39%), total organic matter (47.47-22.36%), and C: N ratio (78.15-54.59%). While, significant increases in pH (9.06-16.47%), total Kjeldahl nitrogen (69.57-139.58%), total available phosphorus (30.30-81.56%), total potassium (8.92-22.22%), and total sodium (50.56-62.12%). The heavy metals like Cr (50-18.60%), Cd (100-75%), Pb (57.14-40%), and Ni (100-50%) were decreased, whereas Zn (8.37-53.77%), Fe (199.03-254.27%), and Cu (12.90-100%) increased significantly. The toxicity of the final vermicompost was shown to be lower in the Genotoxicity analysis, with values ranging between (76-42.33%). The germination index (GI) of Mung bean (Vigna radiata) showed a value ranging between 155.02 and 175.90%. Scanning electron microscopy (SEM) analysis showed irregularities with high porosity of texture in the final vermicompost than in initial mixtures. Fourier Transform-Infrared Spectroscopy (FT-IR) spectra of final vermicompost had low peak intensities than the initial samples. The AS₅₀ feed mixture was the most favorable for the growth and fecundity of Eisenia fetida, emphasizing the role of cattle dung in the vermicomposting process. Thus, it can be inferred that a cost-effective and eco-friendly method (vermicomposting) with the proper amendment of cattle dung and employing Eisenia fetida could transform allopathic sludge into a nutrient-rich, detoxified, stable, and mature vermicompost for agricultural purposes and further could serve as a stepping stone in the allopathic pharmaceutical industry sludge management strategies in the future.

Mitigation of hazards and risks of emerging pollutants through innovative treatment techniques of post methanated distillery effluent - A review

Distillery wastewater has high biological and chemical oxygen demand and requires additional treatment before it can be safely discharged into receiving water. It is usually processed through a biomethanation digester and the end product is the post-methanated distillery effluent (PMDE). Research have shown that PMDE released by molasses-based distilleries is a hazardous effluent that can cause harm to the biota and the environment; it contains elevated amount of total dissolved solids (TDS), total suspended solids (TSS) and excess levels of persistent organic compounds (POPs), heavy metals, phenolic compounds, and salts. The practice of wastewater reuse for irrigation in many water scarce countries necessitates the proper treatment of PMDE before it is discharged into receiving water. Convention methods have been in practice for decades, but innovative technologies are needed to enhance the efficiency of PMDE treatment. Advance physical treatment such as membrane separation technology using graphene, ion-exchange and ultrafiltration membranes; chemical treatment such as advanced oxidation methods, electrocoagulation and photocatalytic technologies; biological treatment such as microbial and enzymatic treatment; and hybrid treatment such as microbial-fuel cell (MFC), genetically modified organisms (GMO) and constructed wetland technologies, are promising new methods to improve the quality of PMDE. This review provides insight into current accomplishments evaluates their suitability and discusses future developments in the detoxification of PMDE. The consolidated knowledge will help to develop a better management for the safe disposal and the reuse of PMDE wastewater.

Detection and identification of hazardous organic pollutants from distillery wastewater by GC-MS analysis and its phytotoxicity and genotoxicity evaluation by using Allium cepa and Cicer arietinum L

Distillery industry generates a huge amount of wastewater, which contains a high strength of organic and inorganic load. Accordingly, this study aims to analyze the physico-chemical pollution parameters and the occurrence of phytotoxic, cytotoxic and genotoxic pollutants in wastewater. The result revealed that values of wastewater parameters were recorded as 13268 mg l^-1 (BOD), 25144 mg l^-1 (COD), 25144 mg l^-1 (TS), and 6634 mg l^-1 (phosphate), while pH was alkaline. The organic compounds detected by GC-MS were quercetin 7,3',4'-trimethoxy, octadecadienoic acid, propanoic acid, glycocholic acid methyl ester, cantaxanthin, etc. The Allium cepa was used for the toxicity test with different concentrations of wastewater showed a significant level of reduction in root growth and length after exposure and the maximum reduction was at 25% and 20%. Phytotoxicity studies were performed using Cicer arietinum L. with different concentrations of wastewater, which showed adverse effects on seed germination, root length, and the effect was associated with the increasing concentration of wastewater. A. cepa root tips were used for the analysis of mitotic index (MI), nuclear abnormalities (NA), and chromosomal aberrations (CA). MI was decreasing significantly from 72% (control) to 33%, 22%, 23%, 21%, and 18% at 5%, 10%, 15%, 20%, and 25% wastewater concentration, respectively. The A. cepa root tip cells showed chromosomal aberrations and nuclear abnormalities like vagrant, stickiness, chromosomal loss, c-mitosis, binucleated, micronuclei, and aberrant cell. This study concluded that the wastewater treatment process is insufficient and the discharged waste needs a proper assessment to know the associated health risk.

Comparing the nutrient changes, heavy metals, and genotoxicity assessment before and after vermicomposting of thermal fly ash using Eisenia fetida

Fly ash (FA) is available in an unstable state and can be ameliorated by vermicomposting. The different ratios of FA viz (FA₁₀, FA₁₅, FA₂₀, FA₂₅, FA₅₀, FA₇₅) were mixed with another organic waste, i.e., cattle dung. Supportive effects of FA were seen on the reproductive parameters of the earthworms up to FA₂₅. Some beneficial changes have been reported in pH, EC, TOC, TKN, TAP, TNa, TK, and potentially toxic heavy metals (Zn, Cu, Cd, Co, Ni, Cr, Pb). The genotoxicity test was performed to assess the toxic effects of the fly ash which has not been done till now. Low genotoxicity potential and high onion root growth were observed in the post-vermicompost samples which were not even reported yet by any other study. These results clearly indicated that the vermicomposting process offers the best option to manage the FA by converting it into an ecofriendly, nutrient-rich, and properly detoxified manure with the help of earthworms which also indicate its economically best-fit applications for the large scale agricultural practices.

Therapeutic effects of royal jelly against sodium benzoate-induced toxicity: cytotoxic, genotoxic, and biochemical assessment

In this study, the protective role of royal jelly (RJ) against the potential toxic effects of sodium benzoate was investigated in Allium cepa L. test material with physiological, genetic, and biochemical parameters. Physiological changes were evaluated by determining weight gain, rooting percentage, root length, and relative injury rate. The genetic evaluations were carried out with chromosomal abnormalities (CAs), micronucleus (MN), tail DNA formation, and mitotic index (MI) ratio parameters. The biochemical evaluations were carried out by determining lipid peroxidation and antioxidant enzyme activities by determining levels of malondialdehyde (MDA), glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT). Further, the interaction of sodium benzoate with antioxidant enzymes was evaluated with molecular docking analysis. The antimutagenic effect of RJ was evaluated as the inhibition of chromosomal abnormalities (CAs) and tail DNA formations. A total of six groups were formed in the study. A. cepa L. bulbs in the control group were treated with tap water; the bulbs in the administration groups were treated with sodium benzoate (100 mg/L), RJ (25 mg/L and 50 mg/L doses), and sodium benzoate-RJ combinations with these doses for 72 h. As a result, it was determined that sodium benzoate application caused inhibition of physiological parameters and MI; induced MN, CAs, and DNA damage; and also caused oxidative stress. Depending on the concentration of RJ application, it reduced sodium benzoate toxicity by showing therapeutic effects in all these parameters. Also, the interaction of sodium benzoate with antioxidant enzyme residues was determined by molecular docking analysis. As a result, it has been understood that abandoning the use of sodium benzoate will be beneficial for the environment and human health and concluded that the use of RJ in the daily diet will be effective in reducing the impact of exposed toxic ingredients.

Physico-Chemical Characterization and Biological Activities of a Digestate and a More Stabilized Digestate-Derived Compost from Agro-Waste

The excessive use of agricultural soils and the reduction in their organic matter, following circular economy and environmental sustainability concepts, determined a strong attention in considering composting as a preferred method for municipalities and industries to recycle organic by-products. Microorganisms degrade organic matter for producing CO₂, water and energy, originating stable humus named compost. The current study analyzed the chemical composition of a cow slurry on-farm digestate and a more stabilized digestate-derived compost (DdC), along with their phytotoxic, genotoxic and antifungal activities. The chemical analysis showed that digestate cannot be an ideal amendment due to some non-acceptable characteristics. Biological assays showed that the digestate had phytotoxicity on the tested plants, whereas DdC did not induce a phytotoxic effect in both plants at the lowest dilution; hence, the latter was considered in subsequent analyses. The digestate and DdC induced significant antifungal activity against some tested fungi. DdC did not show genotoxic effect on Vicia faba using a micronuclei test. Soil treated with DdC (5 and 10%) induced damping-off suppression caused by Fusarium solani in tomato plants. The eco-physiological data indicated that DdC at 5–10% could increase the growth of tomato plants. In conclusion, DdC is eligible as a soil amendment and to strengthen the natural soil suppressiveness against F. solani.

Toxicity evaluation of hospital laundry wastewaters treated by microbial fuel cells and constructed wetlands

Hospital laundries generate high wastewater volumes with the presence of several contaminants. Nevertheless, few studies have investigated the toxicity of these effluents and looked for treatment alternatives that might reduce this eventual toxicity. So, the present study assessed the performance of an integrated system combining a microbial fuel cell (MBFC) and a constructed wetland (CW) to reduce toxic effects of wastewaters generated at a hospital laundry. After collection, raw effluents remained 7 days at the first unit (MBFC) of integrated system. Afterward, they were transferred to the second unit (CW) unit where remained more 7 days totaling a hydraulic detention time of 14 days. The toxicity evaluation involved three different organisms: Daphnia magna (acute ecotoxicity), Lactuca sativa (phytotoxicity) and Allium cepa (phytotoxicity, cytotoxicity, mutagenicity, and genotoxicity). Got results revealed an extremely acute ecotoxicity against D. magna, high phytotoxic effects in the L. sativa and A. cepa assays, and genotoxicity in the A. cepa assay for the untreated effluents. Furthermore, no significant incidence of micronuclei was observed in the raw wastewaters. Regarding the treatment, after the first stage, it was possible to verify that MBFC reduced the toxicity of the wastewaters only in some tested assays (endpoints) while after the CW (second stage) the effluents presented a complete absence of toxicity of the investigated bioassays. Therefore, the use of the integrated system combining two environmentally friendly technologies can be considered promising, since both MBFC and CW presented a complimentary effect with excellent results regarding the reduction of the overall toxicity of hospital laundry wastewaters.