Biodegradation of high doses of commercial pesticide products in pilot-scale biobeds using olive-oil agroindustry wastes

Sustainable indigenous bio-mixture for restoration the soil point source pollution with special reference to chlorpyrifos

Improper pesticide handling is the main cause of contamination of the environment in agricultural systems. This could be caused by leakage of spraying liquid, leftovers, and inappropriate washing of spraying equipment. This study assessed the ability of suggested biomixture modules for remediate repetitive cycles of high chlorpyrifos doses. In three consecutive treatments, four tested modules were contaminated with 160 µg g-1 chlorpyrifos. Chlorpyrifos residues, dehydrogenase activity, and microbial respiration were continuously monitored for 22 weeks. Six bacterial consortia were isolated at the end of the experiment from four treated modules (B+3, BF+3, S+3, and SF+3) and two from untreated modules (B and S). The isolated consortium efficiency in degrading chlorpyrifos was studied. The results revealed that the best chlorpyrifos removal efficiency was achieved when using the stimulated biomixture module (BF) recorded 98%, 100%, and 89%, at the end of three chlorpyrifos treatments, respectively. Such removal efficiency was compatible with the biological activity results of the tested modules: dehydrogenase activity and microbial respiration. There was no difference in the efficiency among the S, B, and BF+3 consortia. The results presented here demonstrate that the combination of vermicompost, wheat straw, soil, and NPK (stimulated biomixture module) can successfully reduce the risk of a point source of pesticide pollution.

Biological treatment of pesticide-containing wastewater from coffee crops: selection and optimization of a biomixture and biobed design

The biopurification systems (BPS) or biobeds are employed for the treatment of pesticide-containing wastewater of agricultural origin. The use of these devices for pesticide removal requires the proper optimization of the composition of biomixtures (BPS active matrix) according to the target pesticides applied on a specific crop and the available materials used in their elaboration. This work aims to design a biomixture for the simultaneous treatment of several pesticides applied in coffee crops, according to local practices in Costa Rica. Three biomixtures containing either coffee husk, coconut fiber or rice husk (as the lignocellulosic substrate) were applied for the removal of 12 pesticides. The profiles of pesticide elimination and the mineralization of radiolabeled chlorpyrifos (14C-chlorpyrifos) revealed that the best performance was achieved with the coconut fiber biomixture, even though similar detoxification patterns were determined in every biomixture (according to immobilization in Daphnia magna and germination tests in Lactuca sativa). The optimization of this biomixture's composition by means of a central composite design permitted the definition of two optimal compositions (compost:soil:coconut fiber, % v/v) that maximized pesticide removal: i. 29:7.3:63.7 and ii. 11:7.3:81.7. The validation of these optimized compositions also included the use of an alternative soil from another coffee farm and resulted in overall DT50 values of 7.8-9.0 d for the pesticide mixture. Considering the removal kinetics in the optimized biomixture, a 1 m3 BPS prototype was dimensioned to be eventually used in local coffee farms. This work provides relevant information for the design and implementation of BPS at on-farm conditions for the treatment of pesticide-containing wastewater of a major crop.

Wide substrate range for a candidate bioremediation enzyme isolated from Nocardioides sp. strain SG-4 G

Narrow substrate ranges can impact heavily on the range of applications and hence commercial viability of candidate bioremediation enzymes. Here we show that an ester hydrolase from Nocardioides strain SG-4 G has potential as a bioremediation agent against various pollutants that can be detoxified by hydrolytic cleavage of some carboxylester, carbamate, or amide linkages. Previously we showed that a radiation-killed, freeze-dried preparation (ZimA) of this strain can rapidly degrade the benzimidazole fungicide carbendazim due to the activity of a specific ester hydrolase, MheI. Here, we report that ZimA also has substantial hydrolytic activity against phthalate diesters (dimethyl, dibutyl, and dioctyl phthalate), anilide (propanil and monalide), and carbamate ester (chlorpropham) herbicides under laboratory conditions. The reaction products are substantially less toxic, or inactive as herbicides, than the parent compounds. Tests of strain SG-4 G and Escherichia coli expressing MheI found they were also able to hydrolyse dimethyl phthalate, propanil, and chlorpropham, indicating that MheI is principally responsible for the above activities.

Using the Pesticide Toxicity Index to show the potential ecosystem benefits of on-farm biobeds

The influent and effluent of two single-cell biobeds (Province of Alberta, Canada) and two dual cell-biobeds (Province of Saskatchewan, Canada) were monitored during a number of growing seasons. A total of 59 unique pesticide active ingredients were detected, with all biobed influent samples (n = 54) and 93% of effluent samples (n = 54) containing pesticide mixtures. About one-half of the effluent samples in both single-cell (56%) and dual-cell (45%) biobeds contained active ingredients that have Groundwater Ubiquity Score (GUS) values >2.8 and so were more likely to move through the biomatrix materials into effluent. The Pesticide Toxicity Index (PTI) calculated for aquatic indicator species (i.e., vascular and nonvascular plants, invertebrates, and fish) was always larger for influent samples (e.g., median PTI >500 for invertebrates in dual-cell biobed) than effluent samples (i.e., median PTI <1). As such, this study demonstrates the potential ecosystem benefits of the broad adoption of on-farm biobeds in the Canadian Prairies for recycling tank rinsate as a strategy to accelerate a green economy. Although biobeds were highly effective in reducing the concentrations for pesticides with a wide range of soil organic carbon coefficient and half-life values, the biobed effectiveness was relatively poor for the herbicides clopyralid, diclofop, fluroxypyr, and imazethapyr. Clopyralid (3.02), fluroxypyr (3.70), and imazethapyr (3.90) all have relatively high GUS values (>2.8) and are thus more likely to be detected in effluent than active ingredients with smaller GUS values. This suggests that further improvements in biosystem design need to be made for optimizing the recycling of these pesticides.

Using biobeds for the treatment of fungicide-contaminated effluents from various agro-food processing industries: Microbiome responses and mobile genetic element dynamics

Agro-food processing industries generate large amounts of pesticide-contaminated effluents that pose a significant environmental threat if managed improperly. Biopurification systems like biobeds could be utilized for the depuration of these effluents although direct evidence for their efficiency are still lacking. We employed a column leaching experiment with pilot biobeds to (i) assess the depuration potential of biobeds against fungicide-contaminated effluents from seed-producing (carboxin, metalaxyl-M, fluxapyroxad), bulb-handling (thiabendazole, fludioxonil and chlorothalonil) and fruit-packaging (fludioxonil, imazalil) industries, (ii) to monitor microbial succession via amplicon sequencing and (iii) to determine the presence and dynamics of mobile genetic elements like intl1, IS1071, IncP-1 and IncP-1ε often associated with the transposition of pesticide-degrading genes. Biobeds could effectively retain (adsorbed but extractable with organic solvents) and dissipate (degraded and/or not extractable with organic solvents) the fungicides that were contained in the agro-industrial effluents with 93.1-99.98% removal efficiency in all cases. Lipophilic substances like fluxapyroxad were mostly retained in the biobed while more polar substances like metalaxyl-M and carboxin were mostly dissipated or showed higher leaching potential like metalaxyl-M. Biobeds supported a bacterial and fungal community that was not affected by fungicide application but showed clear temporal patterns in the different biobed horizons. This was most probably driven by the establishment of microaerophilic conditions upon water saturation of biobeds, as supported by the significant increase in the abundance of facultative or strict anaerobes like Chloroflexi/Anaerolinae, Acidibacter and Myxococcota. Wastewater application did not affect the dynamics of mobile genetic elements in biobeds whose abundance (intl1, IS1071, IncP-1ε) showed significant increases with time. Our findings suggest that biobeds could effectively decontaminate fungicide-contaminated effluents produced by agro-food industries and support a rather resilient microbial community.

Sustainable vs. Conventional Approach for Olive Oil Wastewater Management: A Review of the State of the Art

The main goal of this review is to collect and analyze the recently published research concerning the conventional and sustainable treatment processes for olive mill wastewater (OMW). In the conventional treatment processes, it is noticed that the main objective is to meet the environmental regulations for remediated wastewater without considering the economical values of its valuable constituents such as polyphenols. These substances have many important environmental values and could be used in many vital applications. Conversely, sustainable treatment processes aim to recover the valuable constituents through different processes and then treat the residual wastewater. Both approaches’ operational and design parameters were analyzed to generalize their advantages and possible applications. A valorization-treatment approach for OMW is expected to make it a sustainable resource for ingredients of high economical value that could lead to a profitable business. In addition, inclusion of a recovery process will detoxify the residual OMW, simplify its management treatment, and allow the possible reuse of the vast amounts of processed water. In a nutshell, the proposed approach led to zero waste with a closed water cycle development.

Valorization of food waste as adsorbents for toxic dye removal from contaminated waters: A review

Industrial contaminants such as dyes and intermediates are released into water bodies, making the water unfit for human use. At the same time large amounts of food wastes accumulate near the work places, residential complexes etc. polluting the air due to putrefaction. The need of the hour lies in finding innovative solutions for dye removal from wastewater streams. In this context, the article emphasizes adoption or conversion of food waste materials, an ecological nuisance, as adsorbents for the removal of dyes from wastewaters. Adsorption, being a well-established technique, the review critically examines the specific potential of food waste constituents as dye adsorbents. The efficacy of food waste-based adsorbents is examined, besides addressing the possible adsorption mechanisms and the factors affecting phenomenon such as pH, temperature, contact time, adsorbent dosage, particle size, and ionic strength. Integration of information and communication technology approaches with adsorption isotherms and kinetic models are emphasized to bring out their role in improving overall modeling performance. Additionally, the reusability of adsorbents has been highlighted for effective substrate utilization. The review makes an attempt to stress the valorization of food waste materials to remove dyes from contaminated waters thereby ensuring long-term sustainability.

Oxyfluorfen induces hepatotoxicity through lipo-sugar accumulation and inflammation in zebrafish (Danio rerio)

Oxyfluorfen (OXY) is widely used in agriculture as a herbicide, resulting in its continuous accumulation in the environment. The presence of OXY can be detected in soil and rivers. However, until now, the potential toxicity of OXY to aquatic organisms has not been evaluated. In this study, zebrafish was used as a model animal to evaluate OXY-induced liver toxicity. The study found that 0.25, 0.5, and 1 mg/L of OXY affected the early development of zebrafish and severely damaged the lipid and sugar metabolism in the liver of zebrafish larvae. Furthermore, a metabolic function disorder caused liver damage. OXY also caused inflammation by upregulating the inflammatory factors IL-6, IL-8, and TNF-α, and activated the apoptotic pathway to inhibit hepatocyte proliferation, resulting in zebrafish liver toxicity. Our research showed that OXY had certain toxic effects on zebrafish development and liver and could cause potential harm to other aquatic organisms and humans.

Microbial Technologies Employed for Biodegradation of Neonicotinoids in the Agroecosystem

Neonicotinoids are synthetic pesticides widely used for the control of various pests in agriculture throughout the world. They mainly attack the nicotinic acetylcholine receptors, generate nervous stimulation, receptor clot, paralysis and finally cause death. They are low volatile, highly soluble and have a long half-life in soil and water. Due to their extensive use, the environmental residues have immensely increased in the last two decades and caused many hazardous effects on non-target organisms, including humans. Hence, for the protection of the environment and diversity of living organism's the degradation of neonicotinoids has received widespread attention. Compared to the other methods, biological methods are considered cost-effective, eco-friendly and most efficient. In particular, the use of microbial species makes the degradation of xenobiotics more accessible fast and active due to their smaller size. Since this degradation also converts xenobiotics into less toxic substances, the various metabolic pathways for the microbial degradation of neonicotinoids have been systematically discussed. Additionally, different enzymes, genes, plasmids and proteins are also investigated here. At last, this review highlights the implementation of innovative tools, databases, multi-omics strategies and immobilization techniques of microbial cells to detect and degrade neonicotinoids in the environment.

Microbial growth in biobeds for treatment of residual pesticide in banana plantations

Background

High doses of ethylenebisdithiocarbamate (EBDC) are used in banana production, and unused pesticide mixture (solution) is often disposed of improperly. This can result in soil and water contamination and present an undue risk to rural communities and the environment. An alternative to reduce the environmental impacts caused by pesticide residues is the biobeds treatment. It is necessary to establish if the composition of the proposed biomixtures supports microbial activity to degrade pesticides in biobeds. This research aimed to evaluate the EBDC effect on the distribution and abundance of microbial populations in polluted biomixtures .

Methods

For this purpose, a biomixture based on banana stem, mulch, and Fluvisol soil (50:25:25% v/v) was prepared and polluted with 1,000 mg L^-1 EBDC. The response variables kinetics were determined every 14 days for three months, such as pH, organic matter, moisture, cation exchange capacity, microbial colonies, and cell counts at three depths within the experimental units.

Results

EBDC reduced the number of microbial colonies by 72%. Bacterial cells rapidly decreased by 69% and fungi 89% on the surface, while the decrease was gradual and steady at the middle and bottom of the biobed. The microbial populations stabilized at day 42, and the bacteria showed a total recovery on day 84, but the fungi slightly less. At the end of the experiment, the concentration of EBDC in the biomixture was 1.3-4.1 mg L^-1. A correlation was found between fungal count (colonies and cells) with EBDC concentration. A replacement of the biomixture is suggested if the bacterial population becomes less than 40 × 10⁶ CFU mL^-1 and the fungal population less than 8 × 10⁴ CFU mL^-1 or if the direct cell count becomes lower than 50 × 10⁴ cells mL^-1 in bacteria and 8 × 10² cells mL^-1 in fungi.

Conclusion

The biomixture based on banana stem supports the microbial activity necessary for the degradation of the EBDC pesticide. It was found that fungi could be used as indicators of the pollutant degradation process in the biomixtures. Microbial counts were useful to establish the mobility and degradation time of the pesticide and the effectiveness of the biomixture. Based on the results, it is appropriate to include the quantification of microbial populations to assess the effectiveness of pesticide degradation and the maturity level of the biomixture.

Available Pathways for Operationalizing Circular Economy into the Olive Oil Supply Chain: Mapping Evidence from a Scoping Literature Review

Circular economy (CE) is increasingly seen as a promising paradigm for transitioning agri-food systems towards more sustainable models of production and consumption, enabling virtuous and regenerative biological metabolisms based on strategies of eco-efficiency and eco-effectiveness. This contribution seeks to provide a theoretical and empirical framework for operationalizing the CE principles into the olive oil supply chain, that plays a central role in the agroecological systems of the Mediterranean region. A scoping literature review has been conducted in order to identify the available pathways so far explored by scholars for reshaping the olive oil supply chain from a circular perspective. The analyzed literature has been charted on the base of the circular pathway examined, and according to the supply chain subsystem(s) to which it refers. Results are discussed highlighting the main issues, the technology readiness level of the available pathways, the prevailing approaches and knowledge gaps. A synthetic evidence map is provided, framing visually the scrutinized pathways into the Ellen MacArthur Foundation’s CE ‘butterfly’ graph. The work is intended to be a valuable baseline for inquiring how circularity can be advanced in the specific supply chain of olive oil, and which are the strategic opportunities, as well as the barriers to overcome, in order to foster the transition.

Emerging Strategies for the Bioremediation of the Phenylurea Herbicide Diuron

Diuron (DUR) is a phenylurea herbicide widely used for the effective control of most annual and perennial weeds in farming areas. The extensive use of DUR has led to its widespread presence in soil, sediment, and aquatic environments, which poses a threat to non-target crops, animals, humans, and ecosystems. Therefore, the removal of DUR from contaminated environments has been a hot topic for researchers in recent decades. Bioremediation seldom leaves harmful intermediate metabolites and is emerging as the most effective and eco-friendly strategy for removing DUR from the environment. Microorganisms, such as bacteria, fungi, and actinomycetes, can use DUR as their sole source of carbon. Some of them have been isolated, including organisms from the bacterial genera Arthrobacter, Bacillus, Vagococcus, Burkholderia, Micrococcus, Stenotrophomonas, and Pseudomonas and fungal genera Aspergillus, Pycnoporus, Pluteus, Trametes, Neurospora, Cunninghamella, and Mortierella. A number of studies have investigated the toxicity and fate of DUR, its degradation pathways and metabolites, and DUR-degrading hydrolases and related genes. However, few reviews have focused on the microbial degradation and biochemical mechanisms of DUR. The common microbial degradation pathway for DUR is via transformation to 3,4-dichloroaniline, which is then metabolized through two different metabolic pathways: dehalogenation and hydroxylation, the products of which are further degraded via cooperative metabolism. Microbial degradation hydrolases, including PuhA, PuhB, LibA, HylA, Phh, Mhh, and LahB, provide new knowledge about the underlying pathways governing DUR metabolism. The present review summarizes the state-of-the-art knowledge regarding (1) the environmental occurrence and toxicity of DUR, (2) newly isolated and identified DUR-degrading microbes and their enzymes/genes, and (3) the bioremediation of DUR in soil and water environments. This review further updates the recent knowledge on bioremediation strategies with a focus on the metabolic pathways and molecular mechanisms involved in the bioremediation of DUR.

Vermiremediation of Biomixtures from Biobed Systems Contaminated with Pesticides

Biobeds bioremediation systems are effectively used for minimizing pesticide point-source contamination. For keeping the biobed effectiveness, its biomixture needs to be replaced every so often. The exhausted biomixtures can contain pesticide residues and so they require a special treatment before being discharged into the environment. In this study, we explore the potential of vermiremediation for cleaning up biobed biomixtures contaminated with pesticides. Two biomixtures composed of soil:peat:straw (P) and soil:vermicompost of wet olive cake: olive tree pruning (O), contaminated with high loads of four pesticides, were used. Vermicomposting was carried out by Eisenia fetida earthworms for 12 weeks. Results showed that 50% and 70% of the earthworms colonized the contaminated P and O biomixtures, respectively, but the number of alive earthworms decreased with time just as their weight. The colonization of biomixtures did not significantly affect the dissipation of imidacloprid and tebuconazole, but increased 1.4 fold the dissipation of oxyfluorfen in both biomixtures and that of diuron in biomixture P. Although the presence of high loads of pesticides and the composition of the biomixtures limited the vermiremediation, satisfactory results were obtained for diuron and oxyfluorfen. Complementing vermiremediation with other remediation practices could improve the efficiency of this technology.

Improvement of pesticide removal in contaminated media using aqueous extracts from contaminated biopurification systems

Despite certain limitations, bioaugmentation enhances the efficiency of bioremediation systems. In this study, three aqueous extracts (APE, ACE and APE) from aged residual biomixtures in three biopurification systems (BPSs) exposed to pesticides at a pilot scale were found to improve pesticide removal. The addition of ACEs and AVEs to solutions containing the model compound diuron increased removal rates 6- and 17-fold, respectively, as compared to APEs. These extracts also increased the removal of the metabolite 3,4-dichloroaniline, while AVEs, in particular, were found to remove all pesticides within 9 days. Three metabolites less hazardous than 3,4-dichloroaniline were identified by SPME/GC/MS. AVEs, which also enhance linuron removal in liquid media, were found to increase diuron removal 6-fold in BPSs. We observed an increase in the relative abundance of taxa, such as Chloroflexi, Acidobacteria, Gemmatimonadetes, Firmicutes, Deinococcus-Thermus and especially Proteobacteria (10%), in AV biomixtures, as well as an enrichment of γ-proteobacteria and the actinobacterial genus Dokdonella in AVEs with respect to initial noncontaminated IV biomixture. We demonstrate that extracts containing a pollutant-acclimatized microbiome could be used as part of a bioaugmentation strategy to improve the functioning of on-farm BPSs and contaminated systems.

Influence of different redox conditions and dissolved organic matter on pesticide biodegradation in simulated groundwater systems

Insights into the influence of redox conditions, that is the availability of electron acceptors, and dissolved organic matter (DOM) on pesticide biodegradation in groundwater are key to understanding the environmental fate of pesticides in natural groundwater systems. Here, the influence of redox conditions and supplemental DOM addition on biodegradation of pesticides, 2,4-dichlorophenoxyacetic acid (2,4-D), 2,6-dichlorobenzamide (BAM), mecoprop-p (MCPP) and bentazone, was tested in microcosm and subsequent column experiments. Pesticide degradation, functional genes and changes in specific fractions and quantity of DOM were systematically quantified. In aerobic microcosm experiments, the highest 2,4-D degradation rate was obtained with the presence of more assimilable DOM. In column experiments, minimal pesticide degradation (≤33.77%) in any anaerobic redox conditions was observed in the absence of DOM. However, in the presence of DOM, 2,4-D biodegradation was considerably enhanced under nitrate-reducing conditions (from 23.5 ± 10.2% to 82.3 ± 11.6%) and in a column without external electron acceptor amendment (from -6.3 ± 12.6% to 31.1 ± 36.3%). Observed preferential depletion of the fulvic acid fraction of DOM provides indications for specific functional DOM properties. The qPCR results show an increase in microbial biomass and functional genes (tfdA) in liquid phase after DOM addition. The results of this work provide insights into the interplays among DOM, redox geochemistry, and pesticide biodegradation, and show the potential of a novel approach - DOM addition to groundwater systems - for in situ biostimulation technology to remove pesticides from groundwater systems.

Nanosorbent of hydroxyapatite for atrazine: A new approach for combating agricultural runoffs

The attention of current work was on the fabrication of effective nanoadsorbent of hydroxyapatite (HAp) for the controlled release of atrazine (ATZ) formulation. The ATZ-HAp complex (ATZ@HAp) was able to inhibit the growth of Brassica sp. under in situ conditions. This developed methodology aspires to cease the agricultural runoffs of ATZ applied with the HAp adjuvant and ensure their effective functioning. The efficacy of the protocol was mainly accomplished by adsorbing ATZ over the surface of HAp NPs that restricted its premature runoff and promoted the prolonged herbicidal efficiency. The influence of fundamental parameters i.e., HAp dose, ATZ dose and initial pH on the adsorption process was investigated systematically. The suitability of ATZ@HAp complex for real world application was adjudged after proofing its toxicological behaviour and its role in Zea mays plantations. The complex was found to be non-toxic and nurturing due to its phosphate rich nature. Further investigations of ATZ@HAp complex and its effect on the non-target species will help in establishing an effective framework for their commercial use in agricultural practices.

Innovative application of biobed bioremediation systems to remove emerging contaminants: Adsorption, degradation and bioaccesibility

Biobed bioremediation systems (BBSs) are widely used to prevent point-source pesticide contamination of water. However, these systems have never been investigated for possible elimination of emerging contaminants (ECs). In this study, two biobed systems, involving biomixtures elaborated with soil and raw olive mill cake (SCP) or its vermicompost (SVP), were assayed to determine their effectiveness in removing the ECs diclofenac, ibuprofen and triclosan from effluent wastewater. Adsorption, incubation and bioaccesibility experiments were carried out. The SCP and SVP biomixtures showed greater adsorption capacity than the soil (S), used as reference. In SVP and S, the degradation rates of the ECs applied were similar and over 94% of these compounds was removed after 84 days of incubation. However, SCP biomixture had a lower removal rate and the percentage of ECs removed ranged from 32 to 68%. In SVP, the bioaccesible fraction (E) reveals that approximately 82% of triclosan and diclofenac adsorption occurred in bioaccesible sites, thus explaining the more efficient decontamination observed in this biomixture. The relationship established between the bioaccesible and biodegradable fractions suggests that E values are a useful tool for predicting the endpoints of ECs biodegradation in bioremediation systems. UPLC/Q-TOF-MS analysis of samples showed different metabolite products.