Development and application of a bacteriophage cocktail for Shigella flexneri biofilm inhibition on the stainless steel surface.

Food contamination and biofilm formation by Shigella in food processing facilities are major causes of acute gastrointestinal infection and mortality in humans. Bacteriophages (phages) are promising alternatives to antibiotics in controlling plankton and biofilms in food matrices. This study isolated two novel phages, S2_01 and S2_02, with lytic activity against various Shigella spp. From sewage samples. Transmission electron microscopy revealed that phages S2_01 and S2_02 belonged to the Caudovirales order. On characterizing their lytic ability, phage S2_01 initially exhibited relatively weak antibacterial activity, while phage S2_02 initially displayed rapid antibacterial activity after phage application. A combination of these phages in a 1:9 ratio was selected, as it has been suggested to elicit the most rapid and sustained lysis ability for up to 24 h. It demonstrated lytic activity against various foodborne pathogens, including six Shigella spp. The phage cocktail exhibited biofilm inhibition and disruption abilities of approximately 79.29% and 42.55%, respectively, after 24 h in a 96-well microplate. In addition, inhibition (up to 23.42%) and disruption (up to 19.89%) abilities were also observed on stainless steel surfaces, and plankton growth was also significantly suppressed. Therefore, the phage cocktail formulated in this study displays great potential as a biological control agent in improving food safety against biofilms and plankton.

Effects of salinity and betaine addition on anaerobic granular sludge properties and microbial community succession patterns in organic saline wastewater.

In this study, the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities, sludge characteristics and microbial communities were investigated. The increase in salinity resulted in a decrease in particle size of the granular sludge, which was concentrated in the range of 0.5-1.0 mm. The content of EPS (extracellular polymeric substances) in the granular sludge gradually increased with increasing salinity and the addition of betaine (a typical compatible solute). Meanwhile, the microbial community structure was significantly affected by salinity, with high salinity reducing the diversity of bacteria. At higher salinity, Patescibacteria and Proteobacteria gradually became the dominant phylum, with relative abundance increasing to 13.53% and 12.16% at 20 g/L salinity. Desulfobacterota and its subordinate Desulfovibrio, which secrete EPS in large quantities, dominated significantly after betaine addition.Their relative abundance reached 13.65% and 7.86% at phylum level and genus level. The effect of these changes on the treated effluent was shown as the average chemical oxygen demand (COD) removal rate decreased from 82.10% to 79.71%, 78.01%, 68.51% and 64.55% when the salinity gradually increased from 2 g/L to 6, 10, 16 and 20 g/L. At the salinity of 20 g/L, average COD removal increased to 71.65% by the addition of 2 mmol/L betaine. The gradient elevated salinity and the exogenous addition of betaine played an important role in achieving stability of the anaerobic system in a highly saline environment, which provided a feasible strategy for anaerobic treatment of organic saline wastewater.

Development of a wastewater based infectious disease surveillance research system in South Korea.

Wastewater-based epidemiology has been used in pathogen surveillance for microorganisms at the community level. This study was conducted to determine the occurrence and trends of infectious pathogens in sewage from Yongin city and the relationships between these pathogens and the incidence of infectious diseases in the community. From December 2022 to November 2023, we collected inflow water from six wastewater treatment plants in Yongin city twice a month. The analyzed microorganisms included 15 respiratory viruses, 7 pneumonia-causing bacteria, 19 acute diarrhea-causing pathogens, SARS-CoV-2, Zika virus, hepatitis A virus, poliovirus, Mpox, and measles. They were detected through real-time PCR and conventional PCR. The concentrations of 9 pathogens among them were additionally analyzed using quantitative real time PCR. The correlation was confirmed through statistical analysis with the rate of detection for pathogens reported by the Korea Disease Control and Prevention Agency. Influenza A virus, human adenovirus, and human rhinovirus were moderately correlated (rho values of 0.45 to 0.58). Campylobacter spp. and sapovirus were strong correlated (rho values of 0.62, 0.63). Enteropathogenic E. coli, human coronavirus, and norovirus GII were very strong correlated (rho values of 0.86 to 0.92). We were able to identify the prevalence of respiratory viral infections, pneumonia, and acute diarrhea-causing pathogens in the community through wastewater-based epidemiology data. This study will be helpful in establishing a system for future surveillance of infectious diseases present in sewage.

Modeling the dispersion of wastewater pollutants in Gaza's coastal waters.

The disposal of sewage water in Gaza City has emerged as a significant issue with extensive environmental repercussions. This study seeks to investigate the pollution plume resulting from the discharge of untreated or partially treated sewage water through Gaza City's main outlet into the Mediterranean Sea. Additionally, it aims to predict scenarios for various design configurations of submerged outfalls with either single-port or multi-port diffusers and compare these scenarios against the Environmental Protection Agency (EPA) recreational water quality criteria. According to the EPA, the concentration of Enterococci bacteria at the edge of the mixing zone should not exceed 35 CFU/100 ml to minimize the adverse environmental impact on the marine ecosystem. CORMIX software was utilized as a modeling tool to simulate the dispersion and attenuation behavior of pollutants resulting from this process and to conduct a sensitivity analysis to optimize the design configuration of the sewage disposal system. The simulation considered the influence of ambient conditions (ambient velocity, wind, and seawater density), effluent characteristics (density, flow rate, pollutant concentration, and pollutant decay rate), outfall configuration, and sea bathymetry. Simulation results indicate that a single-port diffuser is unsuitable according to EPA recreation standards. Multi-port unidirectional diffusers, extending 490 m from the shore into the water, meet the required standards. To a lesser extent, the multi-port staged distributor also meets the standards and is more recommended for counter-current situations.

Assessment of Ecological and Health Risks of Potentially Toxic Elements in Soil and Plant Under Long-Term Sewage Wastewater Irrigation.

This paper aimed to evaluate the ecological and health risks for some potentially toxic trace elements (PTEs) in agricultural soils irrigated with sewage wastewater for more than 50 years. Therefore, soil and plant samples were collected from 21 sites at sewage wastewater irrigated area and these samples were analyzed for their contents of PTEs i.e. Cd, Cr, Cu, Ni, and Pb. The risks of PTEs pollution in the study area were analyzed using indices such as the individual and comprehensive potential ecological risk indices (Eri and RI, respectively), hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) model. The results showed that the PTEs in soil samples ranged from 1.70 to 9.90 mg/kg for Cd, from 39.9 to 183.4 mg/kg for Cr, from 31.5 to 655.1 mg/kg for Cu, from 18.8 to 113.1 mg/kg for Ni and from 5.4 to 65.4 mg/kg for Pb. The results also demonstrated that the soil samples were characterized by high to very high ecological risk for Cd. According to the health risk assessment, the mean HQ and HI of the PTEs in soil for adults and children were below the risk threshold of 1, indicating no risk for non-carcinogenic health effects. However, the HI of PTEs via plant consumption was > 1, suggesting a non-carcinogenic health risk. The CR for most plant samples was above the acceptable range. These findings may offer helpful information regarding the ecological and human risks related to PTEs exposure in soil and plants irrigated with wastewater under arid conditions.

Simultaneous adsorption of ammonia nitrogen and phosphate on electro-assisted magnesium/aluminum-loaded sludge-based biochar and its utilization as a plant fertilizer.

Herein, Mg/Al-loaded sludge-based biochar was prepared via electro-assisted impregnation. The structure and chemical analysis of modified sludge-based biochar (MgSBC-0.5(@Al) showed that the material was loaded with MgO and Al2O3. The specific surface area of MgSBC-0.5(@Al) was 11.27 times higher than that of unmodified sludge-based biochar (SBC). The simultaneous adsorption performance of MgSBC-0.5(@Al for ammonia nitrogen (NH4+-N) and phosphate phosphorus (PO43--P) was studied. The maximum adsorption capacities of MgSBC-0.5(@Al for NH4+-N and PO43--P at 298 K were 65.19 and 92.10 mg·g-1, respectively, 4.45 and 6.28 times higher than those of SBC. The external and internal elemental compositions of the modified and unmodified biochar specimens were quantitatively characterized using inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, and X-ray fluorescence spectrometry. The results emphasized the importance of Mg-loading for NH4+-N and PO43--P capture. MgO was mainly loaded on the surface of biochar, enabling adsorption through chemical reactions. Analysis showed that the adsorption of NH4+-N and PO43--P on the modified biochar proceeded simultaneously through multiple mechanisms. Particularly, the adsorption of NH4+-N and PO43--P occurred through the precipitation of struvite and physical adsorption, with PO43--P also adsorbed through the formation of MgHPO4 and CaHPO4. Other data indicated that Al, Ca, and Fe had a trapping effect on the adsorbate. Importantly, the biochar after adsorption could be used as a soil amendment.

Cadmium recovery from acid leachates of Tunisian phosphoric acid purification residues.

The management of cadmium-rich sludges, which are pollutant residues from the phosphorus industry, including the valorization of these sludges through the selective recovery of heavy metals, is a promising prospect. However, there is still a need to develop recovery methods that are both optimized for efficiency, cost-effectiveness, and environmentally friendly. This study aims to enhance cadmium extraction from the polymetallic sludge by optimizing the processes of sulfuric acid (SA) leaching and sodium sulfide precipitation. Key parameters including SA concentration, temperature, solid/liquid ratio, and stirring velocity were optimized to maximize the heavy metals extraction. Over 90% of the Cd and Zn present in the sludge were successfully extracted. Subsequently, investigates the selective precipitation of metal sulfide from acidic leachates (pH < 2), focusing particularly on cadmium. Through the optimization of chemical precipitation parameters (Na2S concentration, temperature, and reaction time), more than 99% of the cadmium was selectively recovered as CdS. The precipitates underwent analysis for mineralogy, chemistry, purity, and particle size. XRD analyses indicated CdS formation in "Greenockite" and "Hawleyite" forms, confirmed by SEM-EDS data, revealing fine powder consisting of micro and nanoparticles (< 0.5 µm) with varied spherical shapes.

Microbial community acclimation during anaerobic digestion of high-oil food waste.

Anaerobic digestion is one of the most promising options for the disposal of biodegradable food waste. However, the relatively high content of oil in food waste inhibits the conversion efficiency of anaerobic digestion because of the accumulation of long-chain fatty acids (LCFAs). In this study, activated anaerobic sludge was acclimated to accommodate high-oil conditions. The methane yield of high-oil food waste digested by the acclimated sludge increased by 24.9% compared to that digested by the raw sludge. To determine the internal changes in the acclimated sludge, the shifts in the microbial communities during the acclimation period were investigated via high-throughput sequencing (HTS) based on the 16 S rRNA gene. The results indicated that Bacteroidetes, Firmicutes, Chloroflexi and Proteobacteria were the dominant bacteria at the phylum level. The acclimation time allows some functional bacterial taxa to proliferate, such as Clostridium and Longilinea, which are able to degrade LCFAs and turn them into small organic molecules that also have nutrient value for other bacteria. Among the archaeal communities, the hydrogenotrophic methanogen Methanobacterium nearly supplanted the acetotrophic methanogen Methanosaeta. The time profiles of volatile fatty acids (VFAs) and pH during this period provided additional evidence for the success of the acclimation. This study demonstrated the effectiveness of acclimation and the dynamic of microbial communities, which further contributed to the management and resource utilization of high-oil food waste.

Optimization of struvite from sewage sludge ash as phosphorus source.

Phosphorus is an essential macronutrient for crop production. Struvite precipitation and reuse from phosphorus-rich sewage sludge are cost-effective measures to improve phosphorus utilization efficiency and decrease its negative environmental impact. In this study, the objectives were to optimize the phosphorus extraction (using sulfuric acid) and recovery (as struvite) processes and determine the most appropriate process conditions using RSM. This was done by evaluating the effect of different parameters such as acid concentration (mol/l) (0.02 to 0.8), H2SO4/ISSA ratio (liquid/solid) (20 to 150 ml/g), and time (0.5 to 4 h) for leaching tests and N: P ratio (1 to 2), Mg: P ratio (1 to 2), and pH (8 to 11) for struvite precipitation. The optimization of the factors affecting PO43--P extraction from SSA by acidic leaching showed that applying 0.5 mol/l H2SO4 and 57 ml/g L/S ratio at 2 h achieved the highest PO43--P extraction (99.8%). The extraction of phosphorus also leached heavy metals; however, using a cation exchange resin, it was possible to effectively remove heavy metals from P-rich solutions. The optimal phosphorus recovery as struvite (98.5%) was achieved at the lowest pH and N/P ratio, while an increase in Mg/P ratio from 1 to 2 positively affected phosphorus recovery. The obtained struvite had a high content 94.6%, and the heavy metal content in struvite was lower than the value of standard, so that the obtained struvite sample can be used as fertilizer.

Recycling of Sewage Sludge: Synthesis and Application of Sludge-Based Activated Carbon in the Efficient Removal of Cadmium (II) and Lead (II) from Wastewater.

The limited supply of drinking water has aroused people's curiosity in recent decades. Adsorption is a popular method for removing hazardous substances from wastewater, especially heavy metals, as it is cheap, highly efficient, and easy to use. In this work, a new sludge-based activated carbon adsorbent (thickened samples SBAC1 and un-thickened samples SBAC2) was developed to remove hazardous metals such as cadmium (Cd+2) and lead (Pb+2) from an aqueous solution. The chemical structure and surface morphology of the produced SBAC1 and SBAC2 were investigated using a range of analytical tools such as CHNS, BET, FT-IR, XRD, XRF, SEM, TEM, N2 adsorption/desorption isothermal, and zeta potential. BET surface areas were examined and SBAC2 was found to have a larger BET surface area (498.386 m2/g) than SBAC1 (336.339 m2/g). While the average pore size was 10-100 nm for SBAC1 and 45-50 nm for SBAC2. SBAC1 and SBAC2 eliminated approximately 99.99% of Cd+2 and Pb+2 out the water under all conditions tested. The results of the adsorption of Cd+2 and Pb+2 were in good agreement with the pseudo-second-order equation (R2 = 1.00). Under the experimental conditions, the Cd+2 and Pb+2 adsorption equilibrium data were effectively linked to the Langmuir and Freundlich equations for SBAC1 and SBAC2, respectively. The regeneration showed a high recyclability for the fabricated SBAC1 and SBAC2 during five consecutive reuse cycles. As a result, the produced SBAC1 and SBAC2 are attractive adsorbents for the elimination of heavy metals from various environmental and industrial wastewater samples.

Pilot-scale in-situ biomethanation of sewage sludge: Effects of gas recirculation method.

The methanation efficiency and operational stability of a 2 m3 pilot-scale in-situ biomethanation reactor were investigated using on-site sewage sludge as the substrate, at a wastewater treatment plant. In parallel, a laboratory-scale study was conducted. Hydrogen conversion efficiencies of 96.7 and 97.5 %, and average methane contents of 84.2 and 83.2 % were obtained, for the laboratory and pilot experiments, respectively. The pilot-scale digester was operated at various conditions for 137 d, of which the last 30 d were stable with a high biomethanation efficiency and an average pH of 8.2. Gas recirculation increased the hydrogen conversion efficiency. When hydrogen injection and gas recirculation were applied separately, a 96 % lower gas recirculation rate was needed to achieve the same hydrogen conversion efficiency, compared to a mixture of hydrogen injection and gas recirculation in the same line. These findings may facilitate the selection of suitable gas recirculation concepts for practical biomethanation applications.

Enhancing sludge thickening in continuous treatment using polymeric bubbles with cationic polymer P2900 and cocamidopropyl betaine.

Sludge thickening is a fundamental stage of treatment. This study investigated the application, in continuous treatment, of polymeric bubbles produced with cationic polymer P2900 and cocamidopropyl betaine (CAPB), a zwitterionic surfactant. The proposed reagent combination aims to form aerated flakes, solid waste structures, and rapidly rising air bubbles, ideal for treatments in compact units. Using this combination, it was possible to achieve a total solids concentration of 45% with the modified bubbles and 25% with the conventional water treatment. This level of thickening occurred under the following operating conditions: initial total solids (TS) concentration of 10 g L-1, a flow rate of 5 L min-1, saturation pressure (psat) of 3 atm, and polymer dosage of 10 mg (gTS)-1. The suggested mechanism of action involves the adhesion of P2900 molecules to CAPB at the air/water interface, forming a lining on the bubble surface. Additionally, polymerized species form due to the residual aluminum (Al) in the sludge, which would occur during flocculation in the helical tubular flocculator (HTF), adsorbing the micelles and bubbles of CAPB. The critical micellar concentration (CMC) of CAPB was 0.26 mmol L-1. Polymeric bubble technology can provide an efficient and cost-effective approach to sludge thickening in continuous treatment.

Bio-transformation of poultry litter and activated sewage sludge to produce biomixtures for the remediation of water polluted with pesticides.

The aim of this study was to formulate novel biomixtures with the ability to dissipate globally used pesticides. For this, an effective stabilization of two wastes, poultry litter and activated sewage sludge, was achieved through a combination of composting and vermicomposting, with the aid of the earthworm Eisenia fetida. Hence, two different mixtures were prepared combining the wastes with and without the addition of sewage sludge, and their physicochemical and microbiological characterization was examined during both processes. Earthworms reproduction was promoted by more than fourteen times the initial number of individuals introduced. This step made it possible to obtain substrates rich in organic matter, stable and non-pathogenic. The resulting vermicomposted substrates (V-C1 and V-C2) were used to produce two different biomixtures with wheat stubble (WS) and soil (S): SWSV-C1 and SWSV-C2, and they were tested for the remediation of a solution of five pesticides (2,4-D, cypermethrin, imidacloprid, acetochlor and dimethoate) in a 119-days assay. Comparisons were made with a WS-only biomixture (SWS) and a soil control. All biomixtures were more successful in dissipating the pesticides than soil; 2,4-D, dimethoate, and acetochlor degradation reached more than 99% in the three biomixtures after 28-56 days of assay. Biomixtures containing either vermicomposts acted faster than SWS, particularly for 2,4-D, dimethoate and cypermethrin. The total microbial activity was found to be higher in the two biomixtures containing vermicompost, which can be linked to their enhanced performance in the degradation of pesticides. Although the germination of Lactuca sativa proved that neither of the three spent biomixtures were phytotoxic at the end (germination index >60%), only SWSV-C1 and SWSV-C2 proved to be safe for the survival of E. fetida. This work confirms that vermicompost improves the success of biomixtures, not only in terms of pesticide removal, but also providing non-toxic spent biomixtures.

Seasonal Prevalence and Detection of Enteric and Respiratory Viruses in Wastewater and Hospitalized Children with Acute Gastroenteritis.

Human enteric and some respiratory viruses are identified to be involved with acute gastroenteritis that can be shed in feces of infected persons into the environment. Understanding the abundance of these viruses in wastewater is significant when assessing the public health impacts associated with discharge of wastewater into the environment. This study aimed to investigate the prevalence and seasonal variation of human enteric adenovirus (HAdV), Aichi virus (AiV-1), bocavirus (HBoV), and respiratory syndrome coronavirus 2 virus (SARS-CoV-2) in wastewater as well as their prevalence among hospitalized children with acute gastroenteritis. The viruses were detected and quantified with real-time PCR. HAdV was the most detected virus in raw sewage (88.5%), treated sewage (28%), and stool gastroenteritis (74%), followed by HBoV (45.8% for raw sewage, 14.6% for treated sewage, and 55.3% for stool samples). The detection rate of AiV-1 was 59.4%, 19.8%, and 62.6% in raw sewage, treated sewage, and stool samples, respectively. The rate of SARS-CoV-2 detection in raw sewage, treated sewage, and stool samples was 33.3%, 7.3%, and 20.6%, respectively. The viral concentrations ranged between 4.50 × 101 and 8.75 × 107 GC/ml in raw sewage samples, 1.20 × 101 and 5.43 × 106 GC/ml in treated sewage samples, and 4.80 × 101 and 9.88 × 108 GC/gram in stool samples. The overall log means of virus reduction during the wastewater treatment process ranged from 1.68 log10 (HAdV) to 3.31 log10 (AiV-1). The peak prevalence of the four viruses in raw sewage samples occurred during the winter season. This study showed the high detection rates of the four targeted viruses in wastewater and demonstrated that virological surveillance of wastewater in local wastewater treatment plants is a suitable model for epidemiological monitoring of diarrheal and respiratory diseases in middle- and low-resource countries.

An in-depth analysis of microbial response to exposure to high concentrations of microplastics in anaerobic wastewater fermentation.

The impact of microplastics (MPs) in anaerobic wastewater treatment on microbial metabolism is significant. Anaerobic granular sludge (AS) and biofilm (BF) are two common ways, and their responses to microplastics will have a direct impact on their application potential. This study investigated the microbial reactions of AS and BF to three types of MPs: polyethylene (PE), polyvinyl chloride (PVC), and a mixture of both (MIX). Results exhibited that MPs reduced methane output by 44.65 %, 55.89 %, and 53.18 %, elevated short-chain fatty acid (SCFA) levels by 95.93 %, 124.49 %, and 110.78 %, and lowered chemical oxygen demand (COD) removal by 28.77 %, 36.78 %, and 33.99 % for PE-MP, PVC-MP, and MIX-MP, respectively, with PVC-MP showing the greatest inhibition. Meanwhile, microplastics also facilitated the relative production of reactive oxygen species (ROS, 40.29 %-96.99 %), lactate dehydrogenase (LDH, 20.01 %-75.02 %), and adenosine triphosphate (ATP, 26.64 %-43.80 %), while reducing cytochrome c (cyt c, 23.60 %-49.02 %) and extracellular polymeric substances (EPS, 17.44 %-26.58 %). AS and BF displayed distinct enzymatic activities under MPs exposure. Correspondingly, 16S-rRNA sequencing indicated that AS was mainly involved in acetate generation by Firmicutes, while BF performed polysaccharide degradation by Bacteroidota. Metatranscriptomic analysis showed AS to be rich in acetogens (Bacillus, Syntrophobacter) and methanogens (Methanothrix, Methanobacterium), while BF contained more fermentation bacteria (Mesotoga, Lentimicrobium) and electroactive microorganisms (Clostridium, Desulfuromonas) under MIX-MP. Moreover, BF exhibited higher glycolysis gene expression, whereas AS was more active in methane metabolism, primarily through the acetoclastic methanogenic pathway's direct acetate conversion. This study provides new insights into understanding the microbial response produced by microplastics during anaerobic wastewater digestion.

Optimizing iron removal from sewage sludge ash for enhanced phosphate fertilizer bioavailability.

Sewage sludge derived fertilizer is a promising solution for phosphorus (P) recovery from biowaste, however, the inherent iron content in the sludge ash (SSA) impedes the P availability of the fused calcium magnesium phosphate fertilizer (FCMP). To achieve the goal of iron removal during the process, carbothermal reduction was adopted for the first time and the performance of carbon addition was systematically evaluated. Results showed that carbon addition at 4.50 % significantly increased the P availability from 9.50 % to 11.00 % and decreased the required amounts of calcium/magnesium. Moreover, ferrophosphate with 20.20 % P can be produced and the melting point of the system can be reduced by manipulating carbon addition. Finally, a process design was provided for the co-production of FCMP and ferrophosphate. This study highlights the addition of carbon to facilitate iron removal in SSA for the production of FCMP with enhanced bioavailability at a reduced energy consumption scenario.

Anode potential regulates gas composition and microbiome in anaerobic electrochemical digestion.

Anaerobic electrochemical digestion (AED) is an effective system for recovering biogas from organic wastes. However, the effects of different anode potentials on anaerobic activated sludge remain unclear. This study confirmed that biofilms exhibited the best electroactivity at -0.2 V (vs. Ag/AgCl) compared to -0.4 V and 0 V. Gas was further regulated, with the highest hydrogen content (47 ± 7 %) observed at -0.2 V. The 0 V system produced the largest amount of methane (70 ± 8 %) and exhibited the greatest presence of hydrogen-utilizing microorganisms. The gas yield at -0.4 V was the lowest, with no hydrogen detected. Excess bioelectrohydrogen at -0.2 V and 0 V caused the co-enrichment of Methanobacterium and Acetoanaerobium, establishing a thermodynamically feasible current-acetate-hydrogen electron cycle to improve electrogenesis. These results provide insights into the regulatory strategies of MEC technology during anaerobic digestion, which play a decisive role in determining the composition of biogas.

Unraveling the characteristics of microplastics in agricultural soils upon long-term organic fertilizer application: A comprehensive study using diversity indices.

Microplastics negatively impact soil health and productivity. Organic fertilizers constitute significant contributors of microplastics in agricultural soils. Nevertheless, comprehensive data on the diversity of microplastics in long-term fertilized soils remain unavailable. In this study, we assessed the presence of microplastics in soils subjected to application of three different organic fertilizers (pig manure, chicken manure, and sludge composts) over 12 years, and evaluated the potential ecological risks posed by microplastic accumulation. The average microplastic abundance in soil was 368.88 ± 207.97 (range: 90-910) items/kg. Microplastic abundance differed among fertilization treatments, with substantial increases of 16.67%, 71.67%, and 61.43% upon low to high application of the three treatments, respectively. Overall, the microplastics predominantly comprised fibers (70.94%) and fragments (25.25%), of which a substantial proportion constituted light-colored microplastics (transparent and white). The size of microplastics was mainly concentrated in the 1-2 mm range (39.96%), with rayon, polypropylene, polyester, and polyethylene being identified as the major types. The risk assessment indices of the three treatments were 229.38, 257.64, and 175.89, respectively, and were all classified as level 4 (high risk). The microplastic diversity integrated index and principal component analysis revealed that microplastics were uniformly distributed throughout the 0-20 cm soil depth consequent to tillage activity. Together, these findings provide a comprehensive assessment of microplastic pollution in long-term fertilized soils and serve as a scientific basis for reducing microplastic contamination in agricultural soils.

Effects of iron-carbon on nitrogen metabolism of floc and aerobic granular sludge.

The aerobic granular sludge (AGS) process had been extensively studied for its simultaneous nitrification and denitrification (SND) capabilities. Iron-carbon (IC) had enhanced AGS nitrogen removal efficiency, but the mechanism remained unclear. In this study, four reactors had been added with 50, 30, 10, and 0 g/L of IC. Total nitrogen removal efficiency increased with IC dosage under the same operation mode. IC enhanced sludge ammonia oxidation rate, denitrification rate, and specific oxygen uptake rate, allowing SND to complete 60 min earlier, potentially reducing wastewater treatment costs. Notably, IC eliminated nitrite accumulation in conventional AGS effluent. IC decreased the abundance of genes and enzyme activities related to NOR expression, while increasing those related to NOS, which may mitigate the potential for nitrous oxide formation by microorganisms. In this study, IC acted as an enzymatic reaction activator, affecting granules more than flocs, with the activity gap gradually decreasing with the IC dosage.

Co-pyrolysis of refinery oil sludge with biomass and spent fluid catalytic cracking catalyst for resource recovery.

Catalytic co-pyrolysis of two different refinery oily sludge (ROS) samples was conducted to facilitate resource recovery. Non-catalytic pyrolysis in temperatures ranging from 500 to 600°C was performed to determine high oil yields. Higher temperatures enhanced the oil yields up to ~ 24 wt%, while char formation remained unchanged (~ 45%) for S1. Conversely, S2 exhibited a notably lower oil yield (~ 4 wt%) than S1. Pyrolysis oil of S1 consisted of phenolics (~ 50% at 600 °C) whereas hydrocarbons were predominant in S2 oil (~ 80% at 600 °C). Catalytic pyrolysis of S1 did not exhibit a substantial impact on oil yields but the oil composition varied significantly. High hydrocarbons, phenolics, and aromatics were obtained with molecular sieve (MS), metal slag, and ZSM-5, respectively. Catalytic co-pyrolysis of S2 with sawdust (SD) in the presence of MS enhanced the oil yield, and the resulting oil consisted of high hydrocarbons (~ 54%) and aromatics (~ 44%).