Search Results (13)

In this study, we aimed to investigate the effects of coagulants and dissolved organic matter (DOM) on the biological toxicity of nano-zinc oxide (nZnO) to key microorganisms involved in biological phosphorus removal during sewage treatment. Polyaluminum chloride and polyferric chloride were selected as coagulants, whereas fulvic acid, glucose, and aspartic acid represented the DOM. The mechanisms through which these chemicals influence nZnO toxicity were also investigated. The results show that polyaluminum chloride and polyferric chloride effectively reduced nZnO toxicity in phosphorus-accumulating organisms, demonstrating their detoxification effects. Similarly, fulvic acid and glucose mitigated nZnO toxicity, whereas aspartic acid displayed dual effects: detoxification at low concentrations and enhanced toxicity at high concentrations. These findings highlight the dual role of sewage treatment additives in enhancing traditional pollutant removal and mitigating the nanoparticle-induced inhibition of microbial biochemical processes. This study clarified the interactions between coagulant chemicals, DOM, and nanoparticles in sewage treatment, offering insights into the regulatory mechanisms that improve treatment efficacy and reduce ecological risks. Full article

Microalga–bacteria consortia are increasingly recognized for their effectiveness in wastewater treatment, leveraging the metabolic synergy between microalgae and bacteria to enhance nutrient removal and overall treatment efficiency. These systems offer a sustainable approach to addressing pollutants such as nitrogen and phosphorus. However, their potential in removing specific contaminants like steroid hormones is less explored. In this study, a natural microbial consortium, A21, has been characterized and isolated from primary sewage treatment in Madrid and its potential for bioremediation of steroid hormone effluents has been evaluated. The A21 consortium includes Alphaproteobacteria genera Sphingopyxis and Pseudorhizobium and the Cyanobacterium Cyanobium. Sphingopyxis (31.78%) is known for biodegradation, while Pseudorhizobium (15.68%) exhibits detoxification abilities. Cyanobium (14.2%) may contribute to nutrient uptake and oxygen production. The effects of pH, nitrogen sources, and Sodium chloride concentrations on growth were evaluated. The optimal growth conditions were determined to be a pH range of 7 to 9, a salt concentration below 0.1 M, and the presence of a nitrogen source. The consortium also demonstrated effective growth across various types of wastewaters (primary, secondary, and tertiary treatment effluents). Additionally, A21 exhibited the ability to grow in the presence of steroids and transform them into other compounds, such as converting androstenedione (AD) into androsta-1,4-diene-3,17-dione (ADD) and β-estradiol into estrone. Full article

Industrial waste and sewage deposit heavy metals into the soil, where they can remain for long periods. Although there are several methods to manage heavy metals in agricultural soil, microorganisms present a promising and effective solution for their detoxification. We isolated a rhizofungus, Aspergillus terreus (GenBank Acc. No. KT310979.1), from Parthenium hysterophorus L., and investigated its growth-promoting and metal detoxification capabilities. The isolated fungus was evaluated for its ability to mitigate lead (25 and 75 ppm) and copper (100 and 200 ppm) toxicity in Triticum aestivum L. seedlings. The experiment utilized a completely randomized design with three replicates for each treatment. A. terreus successfully colonized the roots of wheat seedlings, even in the presence of heavy metals, and significantly enhanced plant growth. The isolate effectively alleviates lead and copper stress in wheat seedlings, as evidenced by increases in shoot length (142%), root length (98%), fresh weight (24%), dry weight (73%), protein content (31%), and sugar content (40%). It was observed that wheat seedlings possess a basic defense system against stress, but it was insufficient to support normal growth. Fungal inoculation strengthened the host’s defense system and reduced its exposure to toxic heavy metals. In treated seedlings, exposure to heavy metals significantly upregulated MT1 gene expression, which aided in metal detoxification, enhanced antioxidant defenses, and maintained metal homeostasis. A reduction in metal exposure was observed in several areas, including normalizing the activities of antioxidant enzymes that had been elevated by up to 67% following exposure to Pb (75 mg/kg) and Cu (200 mg/kg). Heavy metal exposure elevated antioxidant levels but also increased ROS levels by 86%. However, with Aspergillus terreus colonization, ROS levels stayed within normal ranges. This decrease in ROS was associated with reduced malondialdehyde (MDA) levels, enhanced membrane stability, and restored root architecture. In conclusion, rhizofungal colonization improved metal tolerance in seedlings by decreasing metal uptake and increasing the levels of metal-binding metallothionein proteins. Full article

Vermicomposting offers an eco-friendly solution to managing the sewage sludge generated in wastewater treatment plants. The objective of this study was to investigate the microbial community composition, structure and functionality during the vermicomposting of sewage sludge. We analyzed samples of sewage sludge, earthworm casts and vermicompost by applying high-throughput sequencing 16S and ITS rRNA. Most of the bacterial (95%) and fungal taxa (99%) were eliminated and subsequently replaced by other microbial taxa originating from earthworms. Further changes resulted in a vermicompost with a more diverse bacterial (but not fungal) community. In addition, the earthworm activity led to an increase in bacterial and a decrease in fungal alpha diversity, resulting in greater differences in beta diversity between sewage sludge, casts and vermicompost. We also found that bacterial pathways associated with amino acid and plant hormone biosynthesis and antibiotic synthesis were enriched. Vermicomposting successfully eliminated most of the 10 human bacterial pathogens found in the sewage sludge. Simultaneously, parasitic and pathogenic fungal taxa were removed. Overall, vermicompost derived from sewage sludge is safer for disposal on land than raw sludge, particularly regarding their respective microbial compositions. This indicates that it could potentially be used as a soil organic amendment and fertilizer. Full article

This article is devoted to the search for effective ways of neutralizing sewage sludge to obtain sludge-based reclamation material. It was necessary to solve the problems of deodorizing the sludge and fixing the mobile forms of heavy metals in its composition. The composition, effective for solving the assigned problems, was experimentally determined; it included quicklime, sodium hypochlorite and peat. In the presence of sodium hypochlorite in the sludge-based composition, oxidation processes occur with the chemical transformation of ammonia and hydrogen sulfide into non-toxic and odorless compounds. Lime combined with peat promotes the humification of sewage sludge and the binding of heavy metals. Based on the composition that showed the best results, a technology has been developed for the chemical treatment of sewage sludge in situ to produce reclamation material. Full article

Heavy metal toxicity, including lead (Pb) toxicity, is increasing in soils, and heavy metals are considered to be toxic in small amounts. Pb contamination is mainly caused by industrialization (e.g., smelting and mining), agricultural practices (e.g., sewage sludge and pests), and urban practices (e.g., lead paint). An excessive concentration of Pb can seriously damage and threaten crop growth. Furthermore, Pb adversely affects plant growth and development by affecting the photosystem, cell membrane integrity, and excessive production of reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) and superoxide (O₂⁻). Nitric oxide (NO) is produced via enzymatic and non-enzymatic antioxidants to scavenge ROS and lipid peroxidation substrates to protect cells from oxidative damage. Thus, NO improves ion homeostasis and confers resistance to metal stress. In the present study, we investigated the effect of exogenously applied NO and S-nitrosoglutathione in soybean plants Our results demonstrated that exogenously applied NO aids in better growth under lead stress due to its ability in sensing, signaling, and stress tolerance in plants under heavy metal stress along with lead stress. In addition, our results showed that S-nitrosoglutathione (GSNO) has a positive effect on soybean seedling growth under lead-induced toxicity and that NO supplementation helps to reduce chlorophyll maturation and relative water content in leaves and roots following strong bursts under lead stress. GSNO supplementation (200 µM and 100 µM) reduced compaction and approximated the oxidative damage of MDA, proline, and H₂O₂. Moreover, under plant stress, GSNO application was found to relieve the oxidative damage by reactive oxygen species (ROS) scavenging. Additionally, modulation of NO and phytochelatins (PCS) after prolonged metal reversing GSNO application confirmed detoxification of ROS induced by the toxic metal lead in soybean. In summary, the detoxification of ROS caused by toxic metal concentrations in soybean is confirmed by using NO, PCS, and traditionally sustained concentrations of metal reversing GSNO application. Full article

Plants of the Ambrosia genus are invasive and cause many ecological problems, including the oppression of the growth of agricultural crops and native plants, land depletion, and the production of strong allergens. The use of weeds as a sustainable feedstock for biogas production, either methane or hydrogen, is a promising way to fulfill the energy needs of the current generation, eliminate the depletion of non-renewable carbon resources, and preserve the ecosystem degradation caused by invasive species impacts. A diversified microbial community was used as inoculum and Ambrosia artemisiifolia L. biomass as a substrate for anaerobic degradation and methane production. In this regard, the development of biotechnological approaches to ragweed degradation will promote the integration of new renewable energy systems. Herein, we have shown the high effectiveness of combining the processes of anaerobic degradation of plant biomass for methane production and detoxification of meal-containing model sewage by a diversified microbial community. Thus, the maximum methane yield was 56.0 L kg⁻¹ TS. The presence of 500 mg L⁻¹ Cu(II) slightly inhibited methane synthesis, and the methane yield was 38.4 L kg⁻¹ TS. In contrast to a diversified microbial community, the natural microbiome of ragweed almost did not synthesize methane and did not degrade plant biomass (Kd = 2.3). Methanogens effectively immobilized Cr(IV), Cu(II), and Fe(III) during ragweed fermentation at initial concentrations of 100–200 mg L⁻¹. The obtained results showed the high effectiveness of applying a diversified microbial community in a sewage treatment plant for the degradation of a noxious plant, Ambrosia artemisiifolia L. Full article

Phenols are very soluble in water; as a result, they can pollute a massive volume of fresh water, wastewater, groundwater, oceans, and soil, negatively affecting plant germination and animal and human health. For the detoxification and bioremediation of phenol in wastewater, phenol biodegradation using novel bacteria isolated from sewage sludge was investigated. Twenty samples from sewage sludge (SS) were collected, and bacteria in SS contents were cultured in the mineral salt agar (MSA) containing phenol (500 mg/L). Twenty colonies (S1 up to S20) were recovered from all the tested SS samples. The characteristics of three bacterial properties, 16S rDNA sequencing, similarities, GenBank accession number, and phylogenetic analysis showed that strains S3, S10, and S18 were Pseudomonas aeruginosa, Klebsiella pneumoniae, and Klebsiella variicola, respectively. P. aeruginosa, K. pneumoniae, and K. variicola were able to degrade 1000 mg/L phenol in the mineral salt medium. The bacterial strains from sewage sludge were efficient in removing 71.70 and 74.67% of phenol at 1000 mg/L within three days and could tolerate high phenol concentrations (2000 mg/L). The findings showed that P. aeruginosa, K. pneumoniae, and K. variicola could potentially treat phenolic water. All soybean and faba bean seeds were germinated after being treated with 250, 500, 750, and 1000 mg/L phenol in a mineral salt medium inoculated with these strains. The highest maximum phenol removal and detoxification rates were P. aeruginosa and K. variicola. These strains may help decompose and detoxify phenol from industrial wastewater with high phenol levels and bioremediating phenol-contaminated soils. Full article

Environmental pollution with organic substances has become one of the world’s major problems. Although pollutants occur in the environment at concentrations ranging from nanograms to micrograms per liter, they can have a detrimental effect on species inhabiting aquatic environments. Endocrine disrupting compounds (EDCs) are a particularly dangerous group because they have estrogenic activity. Among EDCs, the alkylphenols commonly used in households deserve attention, from where they go to sewage treatment plants, and then to water reservoirs. New methods of wastewater treatment and removal of high concentrations of xenoestrogens from the aquatic environment are still being searched for. One promising approach is bioremediation, which uses living organisms such as fungi, bacteria, and plants to produce enzymes capable of breaking down organic pollutants. These enzymes include laccase, produced by white rot fungi. The ability of laccase to directly oxidize phenols and other aromatic compounds has become the focus of attention of researchers from around the world. Recent studies show the enormous potential of laccase application in processes such as detoxification and biodegradation of pollutants in natural and industrial wastes. Full article

Per- and polyfluoroalkyl substances (PFAS) are recalcitrant pollutants which tend to persist in soils and aquatic environments and their remediation is among the most challenging with respect to organic pollutants. Anaerobic digestion (AD) supplemented with low amounts of carbon materials (CM), acting as electron drivers, has proved to be an efficient process for the removal of organic compounds from wastewater. This work explores the impact of PFAS on different trophic groups in anaerobic communities, and the effect of carbon nanotubes (CNT), activated carbon (AC), and oxidized AC (AC-HNO₃), as electron shuttles on the anaerobic bioremoval of these compounds, based on CH₄ production. The inhibition of the specific methanogenic activity (SMA) exerted by perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), at a concentration of 0.1 mg L⁻¹, was below 10% for acetoclastic and below 15%, for acetogenic communities. Hydrogenotrophic methanogens were not affected by the presence of PFAS. All CM reduced the negative impact of PFAS on the CH₄ production rate, but AC was the best. Moreover, the methanization percentage (MP) of sewage sludge (SS) increased 41% in the presence of PFOS (1.2 g L⁻¹) and AC. In addition, AC fostered an increase of 11% in the MP of SS+PFOS, relative to the condition without AC. AC promoted detoxification of PFOA- and PFOS-treated samples by 51% and 35%, respectively, as assessed by Vibrio fischeri assays, demonstrating the advantage of bringing AD and CM together for PFAS remediation. Full article

Because sewage sludge is contaminated with heavy metals, its disposal in the soil may pose risks to the ecosystem. Thus, heavy metal remediation is necessary to reduce the associated risks. The goal of this research is to introduce a heavy metal resistant species and to assess its phytoremediation, oxidative damage markers and stress tolerance mechanisms. To this end, field research was done to compare the vegetation of polluted sites to that of a healthy site. We found 42 plant species identified in the study, Sesuvium portulacastrum L. was chosen because of its high relative density (10.3) and maximum frequency (100 percent) in the most contaminated areas. In particular, S. portulacastrum plants were characterized by strong Cu, Ni, and As uptake. At the organ level, to control growth reduction and oxidase damage, particularly in roots, increased detoxification (e.g., metallothionein, phytochelatins) and antioxidants mechanisms (e.g., tocopherols, glutathione, peroxidases). On the other hand, flavonoids content and the activity of glutathione-S transferase, glutathione reductase and dehydroascorbate reductase were increased manly in the shoots. These biochemical markers can be applied to select tolerance plant species grown under complex heavy metal contamination. Our findings also introduced S. portulacastrum to reduce soil contamination0associated risks, making the land resource available for agricultural production. Full article

The endocrine disruptor bisphenol A (BPA) is one of the most commonly found micropollutants in the environment. However, the biodegradation of BPA under anaerobic (methanogenic) conditions is still an understudied process in wastewater treatment systems. The current study thus addresses the need for a simple and user-friendly analytical method for the rapid and accurate quantification of BPA in complex matrices such as digested and co-digester sludges. We established a microwave-assisted extraction method, followed by derivatization and gas chromatography–mass spectrometry to quantify BPA by comparing it with a deuterated internal standard. The BPA removal capabilities of three digester sludges and three co-digester sludges were examined under mesophilic methanogenic conditions in biogas plants. The endogenous BPA concentration (dry weight) ranged from 1596 to 10,973 µg kg⁻¹ in digested sewage sludges, and from below the limit of quantification to 9069 µg kg⁻¹ in co-digester sludges. When BPA was added to the sludges, the removal capabilities ranged from not significant to 50% after 21 days of incubation. Biogas production was unaffected by the addition of BPA (228 µg kg⁻¹) to the aqueous sludge. The study demonstrated that BPA could be removed under anaerobic conditions in accustomed inoculates. The findings have far-reaching implications for understanding BPA persistence and detoxification under anaerobic conditions. Full article

The sewage sludge isolate Pseudomonas nitroreducens HBP-1 was the first bacterium known to completely degrade the fungicide 2-hydroxybiphenyl. PacBio and Illumina whole-genome sequencing revealed three circular DNA replicons: a chromosome and two plasmids. Plasmids were shown to code for putative adaptive functions such as heavy metal resistance, but with unclarified ability for self-transfer. About one-tenth of strain HBP-1′s chromosomal genes are likely of recent horizontal influx, being part of genomic islands, prophages and integrative and conjugative elements (ICEs). P. nitroreducens carries two large ICEs with different functional specialization, but with homologous core structures to the well-known ICEclc of Pseudomonas knackmussii B13. The variable regions of ICEPni1 (96 kb) code for, among others, heavy metal resistances and formaldehyde detoxification, whereas those of ICEPni2 (171 kb) encodes complete meta-cleavage pathways for catabolism of 2-hydroxybiphenyl and salicylate, a protocatechuate pathway and peripheral enzymes for 4-hydroxybenzoate, ferulate, vanillin and vanillate transformation. Both ICEs transferred at frequencies of 10⁻⁶–10⁻⁸ per P. nitroreducens HBP-1 donor into Pseudomonas putida, where they integrated site specifically into tRNA^Gly-gene targets, as expected. Our study highlights the underlying determinants and mechanisms driving dissemination of adaptive properties allowing bacterial strains to cope with polluted environments. Full article