Search Results (80)

This study evaluates the agronomic potential of two types of vermicompost—one produced solely from wine industry residues (WIR) and one incorporating sewage sludge (WIR + SS)—under rainfed and deficit irrigation conditions in Mediterranean vineyards. The vermicompost was obtained through a two-phase process involving initial thermophilic pre-composting, followed by vermicomposting using Eisenia fetida for 90 days. The conditions were optimized to ensure aerobic decomposition and maintain proper moisture levels (70–85%) and temperature control. This resulted in end products that met the legal standards required for agricultural use. However, population dynamics revealed significantly higher worm reproduction and biomass in the WIR treatment, suggesting superior substrate quality. When applied to grapevines, WIR vermicompost increased soil organic matter, nitrogen availability, and overall fertility. Under rainfed conditions, it improved vegetative growth, yield, and must quality, with increases in yeast assimilable nitrogen (YAN), sugar content, and amino acid levels comparable to those achieved using chemical fertilizers, as opposed to the no-fertilizer trial. Foliar analyses at veraison revealed stronger nutrient uptake, particularly of nitrogen and potassium, which was correlated with improved oenological parameters compared to the no-fertilizer trial. In contrast, WIR + SS compost was less favorable due to lower worm activity and elevated trace elements, despite remaining within legal limits. These results support the use of vermicompost derived solely from wine residues as a sustainable alternative to chemical fertilizers, in line with the goals of the circular economy in viticulture. Full article

Substantial boosts in the low-energy nano-oxygenation of incoming process water were achieved at a municipal wastewater treatment plant (WWTP) upstream of activated sludge (AS) aeration lanes on a single-pass basis by means of an electric field nanobubble (NB) generation method (with unit residence times of the order of just 10–15 s). Both ambient air and O₂ cylinders were used as gas sources. In both cases, it was found that the levels of dissolved oxygen (DO) were maintained far higher for much longer than those of conventionally aerated water in the AS lane—and at DO levels in the optimal operational WWTP oxygenation zone of about 2.5–3.5 mg/L. In the AS lanes themselves, there were also excellent conversions to nitrate from nitrite, owing to reactive oxygen species (ROS) and some improvements in BOD and E. coli profiles. Nanobubble-enhanced Dissolved Air Flotation (DAF) was found to be enhanced at shorter times for batch processes: settlement dynamics were slowed slightly initially upon contact with virgin NBs, although the overall time was not particularly affected, owing to faster settlement once the recruitment of micro-particulates took place around the NBs—actually making density-filtering ultimately more facile. The development of machine learning (ML) models predictive of NB populations was carried out in laboratory work with deionised water, in addition to WWTP influent water for a second class of field-oriented ML models based on a more narrow set of more easily and quickly measured data variables in the field, and correlations were found for a more facile prediction of important parameters, such as the NB generation rate and the particular dependent variable that is required to be correlated with the efficient and effective functioning of the nanobubble generator (NBG) for the task at hand—e.g., boosting dissolved oxygen (DO) or shifting Oxidative Reductive Potential (ORP). Full article

To analyze the microbiological mechanisms of biological denitrification during low-temperature operations, continuous sampling of influent and activated sludge samples was conducted at the Changchun Municipal Wastewater Treatment Plant. The relative abundance and absolute gene abundance of ammonia-oxidizing bacteria, ammonia-oxidizing archaea, and denitrifying bacteria were determined using high-throughput sequencing technology and reverse transcription–polymerase chain reaction (RT–PCR) technology, respectively. Nitrosomonas and Nitrosospira were the dominant bacteria in ammonia-oxidizing bacteria; the detection rate was 100%; and the abundance distribution fluctuated greatly. The percentages of net proliferation rate greater than −0.05 were 75% and 62.5%, respectively, but the temperature effect was not obvious. The detection rate of Nitrosomonadaceae (norank) was 76.67%, and the percentage of net proliferation rate greater than −0.05 was 50%. The growth of ammonia-oxidizing archaea was limited at low temperature, and the abundance of most bacteria fluctuated greatly. The frequencies of net proliferation rate of Crenarchaeota (norank), Thaumarchaeota (norank), and Nitrososphaera greater than −0.05 were more than 50%. Of the 20 OUTs of denitrifying bacteria, 16 had a net increment rate greater than −0.2/d with a frequency greater than 50 per cent, of which Sinorhizobium and Alphaproteobacteria were detected with a frequency of 100% in activated sludge. The frequency of AOB and denitrifying bacteria net proliferation rate greater than zero during the low-temperature period was relatively high, which ensured the smooth progress of the denitrification process and reasonably explains the microbiological mechanism. In addition, it can be inferred that the migration of influent microorganisms can shape the population structure of denitrifying bacteria, as the net proliferation rate of most bacterial populations was less than 0. Full article

More than 4 billion people yearly suffer from global water scarcity amid climate change, rapid population growth, and growing industrial activity. Due to the high concentrations of recalcitrant organic compounds, refractory wastewater is highly resistant to conventional biological treatment and represents a critical obstacle for water reuse and sustainable water management. A systematic literature review of 35 peer-reviewed articles published from 2010 to 2025 is provided to evaluate the utilization and sustainability potential of advanced oxidation processes (AOPs) for treating recalcitrant wastewater. Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework, the review assesses numerous AOPs, such as ozonation, UV/H₂O₂, Fenton reactions, and photocatalysis, while also evaluating their performance, efficiency, and integration ability. The results show that AOPs demonstrate pollutant removal rates often greater than 96%, reduce sludge formation, and improve effluent biodegradability. They can be applied at different treatment stages, combined with any renewable energy systems, and therefore can scale and be sustained, thereby aligning with UN Sustainable Development Goal 6. AOPs provide a technically feasible and eco-friendly solution for higher quality wastewater treatment. In the face of increasing pressure on global water resources, and the urgent need for sustainable water resource management, this study offers valuable insights for policymakers and practitioners aiming to adopt resilient and circular strategies for water. Full article

The extraction of underground resources has accelerated globally, in response to the demands of advancing technology and the rapidly growing population. The increase in drilling activities has caused an increase in environmental pollution problems caused by waste generated during drilling activities, namely drilling sludge and drilling wastewater. In this study, the treatability of wastewater generated during drilling operations in a basin, where an underground gas storage area was created, was investigated using an electrocoagulation (EC) process, using different electrode pairs. The removal efficiencies of the pollution parameters were determined using the response surface method. The wastewater parameters included different organic and inorganic pollutants, such as sodium, chloride, magnesium, and chemical oxygen demand (COD). The concentrations of sodium, chloride, and COD in drilling industry wastewater were found to be very high, at 128,567, 185,292, and 7500 mg/L, respectively. The data obtained in this study yielded a removal efficiency of approximately 65% and above. Sodium achieved the highest pollutant removal efficiency of 85% and above. The statistical values were interpreted for all the pollutants and the suitability of second-degree regression was observed. Full article

Hydrodynamic cavitation (HDC) as a pre-treatment method is innovative and has potential for wide-scale industrial applications. The novelty of this research involves evaluating the enzymatic activity in the anaerobic co-digestion (AcD) of hydrodynamically cavitated coffee waste (CW) and municipal sewage sludge (SS) as well as its influence on the AcD performance. The effectiveness of AcD was assessed on the basis of changes in the physico-chemical composition of the feedstock and digestate as well as the biogas/methane yield, and attention was paid to the effect of coffee waste on enzyme activity, including that of β-Glucosidases (β-Glu), protease (PR), urease (URE), phosphomonoesterases acid (ACP) and alkaline (ALP). Moreover, the changes in the heavy metal content after the AcD of CW and SS were investigated. Comparing the enzymatic activity of the feedstock and digestate, we observed that the URE, ACP and ALP activities were 4.5 to 11 times higher for the feedstock than the enzyme activities in the digestate. Moreover, when using CW cavitated for 30 min, the highest enzymatic activity in both the feedstock and digestate occurred. The results indicated that the relationship between the β-Glu activity and biogas yield showed the strongest positive correlation (r = 0.98 at p ≤ 0.05). At the same time, a positive correlation between the PAC, PAL, URE and PR activity and methane yield and methane content at p ≤ 0.05 was observed. The obtained results allow us to conclude that, in the future, such a digestate could be used as a bio-fertilizer to improve degraded soil to activate microbial populations. Full article

Knowledge of the impact of chemicals on the environment is important for assessing the risks that chemicals can generate in ecosystems. With the help of pilot-scale micro-tests, it was possible to evaluate the biological sludge in terms of its chemical and biological composition, information that can be applied on an industrial scale in treatment plants. The important parameters analyzed in the evaluation of the biodegradability of wastewater were pH, chemical composition (NH₄⁺, NO₃⁻, NO₂⁻, and PO₄³⁻), dry substance (DS), inorganic substance (IS), and organic substance (OS), and the biological oxygen demand (BOD)/chemical oxygen consumption (COD) ratio. The examination revealed the presence of free active ciliates Aspidisca polystyla, Lyndonotus setigerum, Vorticella microstoma, fixed by Zooglee, Paramecium sp., Opercularia, Colpoda colpidium, Euplotes, Didinum nasutum, Stentor, and Acineta tuberosa, metazoa Rotifers, filamentous algae, Nostoc and Anabena, and bacteria Bacillus subtilis, Nocardia, and Microccocus luteus. The novelty of this study lies in the fact that we carried out a study to evaluate the population of microorganisms starting from the premise that the probability of biodegradation of substances is directly proportional to the number of microorganisms existing in the environment and their enzymatic equipment. Full article

The removal of nitrogen compounds in wastewater has been successfully developed with various activated sludge-based processes. Microorganisms immobilized in media would enhance biological efficiency by the increase in biomass concentration; however, the microbial community composition in media has not been revealed. Attached microbial communities on immobilization media were analyzed after the operation of the wastewater treatment process, comparing aerobic and anoxic reactors. A modified Ludzack–Ettinger (MLE) process was operated with immobilized media with polyvinyl alcohol and polyethylene glycol. The mixed liquor suspended solid (MLSS) concentration in an aerobic reactor was maintained at 50,000 mg/L and 40,000 mg/L in an anoxic reactor by the media. A maximum of 99% of ammonium nitrogen from the influent was calculated to be oxidized; however, the organic nitrogen produced from microbial growth reduced the overall oxidation rate. The denitrification rate increased with the addition of glucose to adjust the carbon-to-nitrogen (C/N) ratio. Based on the total nitrogen concentration, the nitrogen removal efficiency was calculated to be 48.2% following the adjustment of the C/N ratio. A phylogenetic analysis of the microbial community in immobilized media using next-generation sequencing (NGS) revealed the dominance of nitrifying and denitrifying microorganisms in the aerobic and anoxic reactors, respectively. Sequences amplified using V3–V4 region primers of the 16S rRNA gene yielded 531,188 base pairs (bp) and 396,844 bp reads from the aerobic and anoxic reactors, respectively. Operational taxonomic units (OTUs) were identified at both the phylum and genus levels, with a total of 594 from the aerobic reactor and 375 from the anoxic reactor. Proteobacteria was the dominant phylum in both the aerobic and anoxic reactors, comprising 39.7% of the aerobic reactor and 65.9% of the anoxic reactor. The dominant genera in the aerobic reactor were Nitrospira and Povalibacter. Forty-five percent of the total number of OTUs consisted of known nitrification-related genera in the aerobic reactor. In contrast, the dominant genera in the anoxic reactor were Desulfomicrobium, Desulfobulbus, and Methyloversatilis. A total of 63% of the genera associated with denitrification, including Dechloromonas and Flavobacterium, were found in the anoxic reactor. The population of microorganisms in each reactor was compared in terms of diversity by the QIIME 2 algorithm. The Chao1 index values of α-diversity were 606.05 for the aerobic reactor and 415.53 for the anoxic reactor, indicating greater population diversity in the aerobic reactor compared to the anoxic one. The widespread distribution of nitrification activities among various groups has led to diverse population characteristics in the aerobic environment, particularly within the attached community. The microbiological community present in immobilized aerobic and anoxic media will contribute to future microbial studies on wastewater treatment processes. Full article

Although organic amendment has been widely accepted to be capable of facilitating soil agglomeration in coastal salt-affected soils, quantitative characterization with respect to how abiotic and biotic components drive the formation and stabilization of soil aggregates remains largely unexplored and poorly understood. In the current study, wet-sieving, Miseq sequencing, etc., were employed to study the impacts of different application amounts of sewage sludge on soil aggregates, physicochemical properties, enzyme activities, and microbial core microbiomes in coastal saline soils. The results indicated that sewage sludge was conducive to soil agglomeration, abiotic constraint alleviation, microbial activity enhancement, and bacterial and fungal community stabilization and functionalization. The results derived from variation partitioning analysis and the structural equation model showed that elevated soil organic carbon and mitigated salinization were dominant abiotic factors that directly drove the stabilization and functionalization of bacterial and fungal microbiomes. In addition, bacterial families (e.g., Xanthomonadaceae, Rhodospirillaceae, and Micrococcaceae) and fungal genera (e.g., Trichoderma, Cephaliophora, Mortierella, and Penicillium) were potential functional microbial populations related to soil agglomeration in organic amended coastal salt-affected soils. Together, these abiotic and biotic agents jointly drove soil agglomeration and totally explained 87% of the variations in soil aggregates. Collectively, this study highlighted the approach and effectiveness of the impacts of organic amendment on soil agglomeration in coastal salt-affected land based on qualitative and quantitative analysis, which would enhance our knowledge with respect to coastal salt-affected soil quality indication and development. Full article

Plastic waste pollution has become a global crisis, with millions of tons of plastic expected to accumulate in landfills and in natural environments, posing a serious threat to wildlife and human health. As current recycling methods remain inefficient, there is an urgent need for innovative enzymatic solutions to break down plastics and enable a circular economy approach. In this study, we explore the plastic-degrading potential of microorganisms enriched from activated sludge (AS) sourced from a municipal wastewater treatment plant (WWTP)—a known microplastic-contaminated industrial niche. Five microbial consortia (i.e., microbiomes) were enriched under selective pressure using low-carbon conditions and high concentrations of polyester polymers, including post-consumer PET, post-consumer PLA, and virgin PLA. Enrichment was performed for 100 days at 37 °C and 50 °C, followed by microbiomes isolation and metagenomic analysis to identify plastic-active bacteria and their enzymes. The results revealed that PLA polymers, but not post-consumer PET, were effectively degraded by the microbiomes, as confirmed by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC), showing significant molecular weight reduction compared to the abiotic controls. Microbial community analysis highlighted a distinct enrichment profile driven by the polymer composition and the temperature. At 50 °C, the Bacillales order became the predominant population, whereas at 37 °C, a more diverse community within the Proteobacteria and Actinobacteria phyla were selected. Nonetheless, the enriched microbial communities at both temperatures included phyla with members known for polyester degradation. Moreover, at 50 °C, enrichment of putative PET/PLA hydrolases was also observed. These findings suggest that AS microorganisms are a reservoir of polyester-active enzymes, particularly PLA-depolymerases, and hold promise for advancing biotechnological strategies to mitigate plastic pollution through re- and up-cycling. Full article

The growth of the global population, coupled with concomitant economic development, has resulted in the generation of a substantial quantity of waste. The transition of the European Union’s economy towards a closed-loop model is prompting a comprehensive search for waste management concepts across a range of industrial sectors. The objective of this study is to valorise deinking paper sludge, which has a high potential for soil formation due to its high organic matter content. To produce organic–mineral fertiliser, the deinking sludge was subjected to acid hydrolysis, then neutralised with KOH solution and enriched with poultry litter ash. The final products were characterised in terms of their nutrient and heavy metal content. The bioavailability of phosphorus, along with the forms in which it occurs in fertilisers, was determined through the implementation of a five-step fractionation procedure. Furthermore, an eight-week incubation period was conducted to assess the fertilisers’ performance in soil. Soil samples were tested on a weekly basis for pH, water-soluble and bioavailable phosphorus content using the spectroscopic method after previous extraction in water and Bray’s solution, and catalase activity using the titrimetric method. The resulting fertilisers were found to meet the requirements for organo-mineral fertilisers and were categorised as PK-type fertilisers with a total nutrient content of 24.6–39.3%. Fractionation studies demonstrated that the fertilisers contained 20–30% of the total potentially bioavailable phosphorus. Furthermore, the long-term release of phosphorus from the fertilisers was confirmed through incubation studies. Additionally, the fertilisers were observed to contribute to an increase in catalase activity in the soil. Full article

This study investigated the purification of pollutants in runoff rainwater by constructing a micro-ecosystem using waste-activated sludge (WAS) and riverbed sludge (RBS) as inoculums in combination with pervious concrete. The research results showed that the best hydraulic retention time (HRT) was 9 h. The COD and ammonia nitrogen (NH₄⁺-N) removal of the waste-activated sludge ecosystem (WASE) was 62.67% and 71.21%, respectively, while the riverbed sludge ecosystem (RBSE) showed COD and NH₄⁺-N removal percentages of 46.05% and 66.55%, respectively. The analysis of the genetic metabolism of microbial genes showed that the system was microbially enhanced with extensive and diverse populations. At the phylum level, the microorganisms responsible for degrading organic matter were mainly Firmicutes and Actinobacteriota. At the genus level, the Trichococcus genus was dominant in the WASE, while the Dietzia, norank_f__Sporomusaceae and norank_f__norank_o__norank_c__BRH-c20a genera were the central bacterial populations in the RBSE. The proliferation of phylum-level bacteria in the WASE was relatively large, and the genus-level bacteria demonstrated a better removal efficiency for pollutants. The overall removal effect of the WASE was better than that of the RBSE. The application analyses showed that a WASE is capable of effectively accepting and treating all rainfall below rainstorm levels and at near-full rainstorm levels under optimal removal efficiency conditions. This study innovatively used wastewater plant waste-activated sludge combined with pervious concrete to construct a micro-ecosystem to remove runoff rainwater pollutants. The system achieved pollutant removal comparable to that of pervious concrete modified with adsorbent materials. An effective method for the collection and pollutant treatment of urban runoff rainwater is provided. Full article

In order to investigate the enhancement mechanism of modified three-dimensional elastic filler (MTEF) on the nitrogen removal performance of the integrated fixed-film activated sludge (IFAS) process, and to clarify the interactions between competition and synergy between activated sludge and biofilm in the IFAS system, an IFAS reactor (T2) filled with MTEF was employed for the study, while a sequencing batch reactor activated sludge process (SBR) reactor (T1) was utilized for comparison. IFAS and SBR reactors were operated over an extended period at ambient temperature to assess the enhancement of pollutant removal performance with the addition of the filler to investigate the competitive dynamics between activated sludge and biofilm under varying influent water qualities (C/N, N/P, and organic loading), and to analyze the synergistic relationship between activated sludge and biofilm at the microbial level using high-throughput sequencing technology. The results demonstrate that throughout the entire operational phase, reactor T2 exhibited superior pollutant removal efficiency. Compared to reactor T1, reactor T2 achieved an average increase in the removal rates of COD, ammonia nitrogen, and total nitrogen by 13.07%, 12.26%, and 28.96%, respectively. The findings on the competitive dynamics between activated sludge and biofilm indicate that the nitrification volumetric load of the IFAS system is significantly higher than that of a pure activated sludge system, suggesting that the IFAS system possesses enhanced nitrification capabilities. Furthermore, when dealing with wastewater characterized by low C/N ratios and high phosphorus pollution, or under substantial organic loads, the biofilm holds a competitive edge and the IFAS system exhibits improved stability. High-throughput sequencing data reveal that the microbial community structures in activated sludge and biofilm can influence each other, thereby enabling the IFAS system to effectively enrich denitrification-related functional microbial populations. Additionally, the biofilm has a certain enhancing effect on the expression levels of nitrogen metabolism-related functional genes in the activated sludge phase microorganisms, indicating that, in addition to competitive interactions, there is also a synergistic effect between the biofilm and activated sludge. Full article

Filamentous bacteria are one of the main components of activated sludge microorganisms, which not only support flocculent bacteria in forming sludge flocs but also easily lead to sludge bulking. This article summarizes the high-throughput sequencing technology and database construction that integrates the FISH probe and 16s rRNA gene of filamentous bacteria. The detection frequency and abundance were statistically analyzed to determine the core filamentous bacteria. The filamentous bacteria searchable in the NCBI database belong to six phyla and 42 genera, with a total of 94 species. The core filamentous bacteria in the expanded activated sludge include Microthrix parvicella (M. parvicella), type 0092, Mycobacterium fortuitum, etc. The physiological ecology of the core filamentous bacteria is discussed in detail, aiming to establish targeted sludge expansion control strategies, reduce the incidence and harm of sludge expansion, and propose that future research needs to promote further development in the field of environmental microbiology. Full article

Many pharmaceuticals (PhMs), compounds for the treatment or prevention of diseases in humans and animals, have been identified as pollutants of emerging concern (PECs) due to their wide environmental distribution and potential adverse impact on nontarget organisms and populations. They are often found at significant levels in soils due to the continuous release of effluent and sludge from wastewater treatment plants (WWTPs), the release of which occurs much faster than the removal of PhMs. Although they are generally present at low environmental concentrations, conventional wastewater treatment cannot successfully remove PhMs from influent streams or biosolids. In addition, the soil application of animal manure can result in the pollution of soil, surface water, and groundwater with PhMs through surface runoff and leaching. In arid and semiarid regions, irrigation with reclaimed wastewater and the soil application of biosolids are usual agricultural practices, resulting in the distribution of a wide number of PhMs in agricultural soils. The ability to accurately study the fate of PhMs in soils is critical for careful risk evaluation associated with wastewater reuse or biosolid return to the environment. The behavior and fate of PhMs in soils are determined by a number of processes, including adsorption/desorption (accumulation) to soil colloids, biotic (biodegradation) and abiotic (chemical and photochemical degradation) degradation, and transfer (movement) through the soil profile. The sorption/desorption of PhMs in soils is the main determinant of the amount of organic chemicals taken up by plant roots. The magnitude of this process depends on several factors, such as crop type, the physicochemical properties of the compound, environmental properties, and soil–plant characteristics. PhMs are assumed to be readily bioavailable in soil solutions for uptake by plants, and such solutions act as carriers to transport PhMs into plants. Determining microbial responses under exposure conditions can assist in elucidating the impact of PhMs on soil microbial activity and community size. For all of the above reasons, soil remediation is critical when soil pollutants threaten the environment. Full article