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The application of anaerobic digestion (AD) in the treatment of food waste (FW) has become widespread. However, the presence of inert substances, such as bones, ceramics, and shells, within FW introduces a degree of uncertainty into the AD process. To clarify this intricate issue, this study conducted an in-depth investigation into the influence of inert substances on AD. The results revealed that when inert substances were present at a concentration of 0.08 g/g VSS, methane productivity in the AD process was significantly augmented by 86%. Subsequent investigations suggested that this positive effect was primarily evident in various biochemical processes, including solubilization, hydrolysis acidification, methanogenesis, and the accumulation of extracellular polymeric substances. Metagenomic analysis showed that inert substances enhance the relative abundance of hydrolytic bacteria and have a pronounced impact on the relative abundance of hydrogenotrophic methanogens (Methanosarcina) and acetotrophic methanogens (Methanobacterium). Additionally, inert substances significantly increased the relative abundance of functional genes in oxidative phosphorylation, a pivotal pathway for ATP synthesis. Furthermore, inert substances had a substantial effect on the functional genes related to the metabolic pathways associated with methanogenesis (both hydrogenotrophic and acetotrophic). This comprehensive study shed light on the substantial impact of inert substances on the AD of food waste, contributing to an enhanced understanding of the underlying mechanisms of anaerobic fermentation.
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Perda e Desperdício de Alimentos , Eliminação de Resíduos , Anaerobiose , Reatores Biológicos , Fosforilação Oxidativa , Alimentos , Metano , Esgotos/microbiologiaRESUMO
Concentrated leachate (CL), characterized with high content salts and compositional complexity of dissolved organic matter (DOM), is difficult to degrade. Understanding the CL from molecular insight level is the requirement for further disposal based on their components. Here, typical CL samples were collected from the multi-stage membrane separation process in a large-scale leachate plant, including nanofiltration (NF), primary ultrafiltration (PUF), secondary nanofiltration (SNF), and reverse osmosis (RO). More than 95% of DOM was removed from raw CL, of which about 3/4 flowed into PUFCL and 1/5 flowed into SNFCL. DOM with macro-molecular weight (>500 Da, 30.46%) and highly unsaturated compounds (double-bond equivalents >15) were detected in PUFCL. Nearly half of DOM was CHO-only compounds (42.04%) in SNFCL. PUFCL was abundant in heteroatom species with higher-order oxygen (O ≥ 10), which was coincident with the trend of humic substance distribution (humic substance >1/2). Based on these properties results, advanced oxidation processes, such as ozonation, might be the right process for SNFCL rich in heteroatom species with low-order oxygen (O < 10). Abundant disulfides (S2O2-6 classes, 20.19%) and monovalent salts existed in ROCL, which should be removed from the system. These findings might provide basic information for the treatment of CLs from different membranes.
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Matéria Orgânica Dissolvida , Poluentes Químicos da Água , Filtração , Substâncias Húmicas/análise , Oxirredução , Ultrafiltração , Poluentes Químicos da Água/análiseRESUMO
Thermophilic solid-state anaerobic digestion (SS-AD) of agricultural wastes, i.e., corn straw, cattle manure, and vegetable waste, was carried out in this study. The effects of temperature (40-60°C), initial solid content (ISC, 17.5-32.5%), and C/N ratio (15-32 : 1) on biogas production were evaluated using a Box-Behnken experimental design (BBD) combined with response surface methodology (RSM). The results showed that optimization of process parameters is important to promote the SS-AD performance. All the factors, including interactive terms (except the ISC), were significant in the quadratic model for biogas production with SS-AD. Among the three operation parameters, the C/N ratio had the largest effect on biogas production, followed by temperature, and a maximum biogas yield of 241.4 mL gVS-1 could be achieved at 47.3°C, ISC = 24.81%, and C/N = 22.35. After 20 d of SS-AD, the microbial community structure under different conditions was characterized by high-throughput sequencing, showing that Firmicutes, Bacteroidetes, Chloroflexi, Synergistetes, and Proteobacteria dominated the bacterial community, and that Firmicutes had a competitive advantage over Bacteroidetes at elevated temperatures. The biogas production values and relative abundance of OPB54 and Bacteroidia after 20 d of SS-AD can be fitted well using a quadratic model, implying that OPB54 and Bacteroidia play important roles in the methanogenic metabolism for agricultural waste thermophilic SS-AD.
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Anaerobiose/fisiologia , Carbono/química , Esterco/microbiologia , Nitrogênio/química , Verduras/química , Zea mays/química , Animais , Bactérias/crescimento & desenvolvimento , Biocombustíveis/microbiologia , Reatores Biológicos/microbiologia , Bovinos , Microbiota/fisiologia , TemperaturaRESUMO
Antibiotics, antimicrobial resistance determinants and human pathogens are new types of environmental pollutants that pose a great threat to human health. Wastewater treatment plants (WWTPs) are important sources of novel pollutants; however, few studies have investigated their impact on surrounding natural water. Therefore, this study used a WWTP as the entry point to explore WWTP removal efficiency of antibiotics, antimicrobial resistance determinants and human pathogens and further analyze the impact of WWTP effluent on receiving waters. The investigated WWTP had a good removal effect on fluoroquinolones, macrolides, lincomycin, sulfanilamide, tetracycline and chloramphenicol antibiotics in wastewater, and the concentration of antibiotics in the WWTP's effluent was reduced by >80% relative to the influent. In addition to cmlA, the effect of the WWTP on antimicrobial resistance determinants removal was poor, although the effluent from the WWTP had no effect on the abundance of antimicrobial resistance determinants in the receiving water. However, with the dilution of receiving water, the abundance of antimicrobial resistance determinants gradually decreased. The WWTP could reduce the abundance of bacteria by 1000 times from influent water to effluent water. The major bacteria in the influent and effluent were Bacteroidetes and Proteobacteria. After effluent is discharged into receiving water, Cyanobacteria proliferate in large quantities, which can affect the microbial structure in the environment.The abundance of Acinetobacter, which was the predominant potential human pathogen in local wastewater, decreased dramatically after wastewater treatment. We also conducted an ecological risk assessment of the antibiotics identified and found that the ecological risk AZM and CLR posed to aquatic organisms was high. Overall, we identified the efficiency of WWTP control of antibiotics, antimicrobial resistance determinants and potential human pathogens and the impact of WWTP effluent on receiving water and provided data to support the control of the investigated pollutants.
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Bactérias/isolamento & purificação , Farmacorresistência Bacteriana , Águas Residuárias/microbiologia , Microbiologia da Água , Purificação da Água , Anti-Infecciosos/análise , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/farmacologia , Bactérias/classificação , Bactérias/efeitos dos fármacos , China , Humanos , Medição de Risco , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/estatística & dados numéricosRESUMO
Stereoscopic porous carbons have shown good potential in humic acid (HA) removal. In this work, a novel stereoscopic porous activated carbon (SPAC) was designed and synthesized via the self-assembly of a hydrogel based on food waste during in-situ polymerization, vacuum drying, carbonization, and activation. Then, the SPAC was functionalized with 3-aminopropyltriethoxysilane (APTES) and the adsorption behavior of the modified SPAC (SPAC-NH2) was studied systematically. The effects of pH, contact time, initial concentration of HA, and adsorbent dose were investigated, showing that optimal HA removal efficiency (>98.0%) could be achieved at an initial HA concentration of 100â¯mg/L. The experimental adsorption isotherm data was fitted to the Langmuir model with a maximum adsorption capacity of 156.0â¯mgâ¯HA/g SPAC-NH2. Analysis of the mechanism indicated that the removal of HA was mainly realized through the amidization reaction between the COOH groups of HA and the NH2 groups of APTES. All of the above results showed that SPAC-NH2 powder is an efficient, eco-friendly, and reusable adsorbent which is suitable for the removal of HA from wastewater.
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Resinas Acrílicas/química , Carvão Vegetal/química , Alimentos , Substâncias Húmicas , Hidrogéis/química , Resíduos , Água/química , Adsorção , Concentração de Íons de Hidrogênio , Porosidade , Fatores de TempoRESUMO
Biowaste-derived hydrochar is an emerging close-to-natural product and has shown promise for soil improvement and remediation, but the environmental behavior of the dissolved organic matter released from hydrochar (HDOM) is poorly understood. Focusing on the typical mulch film plasticizer diethyl phthalate (DEP), we investigated the effect of HDOM on the sorption behavior of DEP on soil. The relatively low concentration of HDOM (10 mg L-1, 25 mg L-1) decreases the sorption quantity of DEP on soil, while it increases by a relatively high concentration, 50 mg L-1. The transformation from multilayer to monolayer sorption of DEP on soil occurs as the concentration of HDOM increases. The tryptophan-like substance is the main component of HDOM sorbed to soil, reaching 49.82 %, and results in competition sorption with DEP. The soil pores are blocked by HDOM, which limits the pore filling and mass transfer of DEP, but partitioning is significantly enhanced. The surface functional groups in HDOM are similar to those in soil, and chemical sorption, mainly composed of hydrogen bonding, exists but is not significantly strengthened. We identified the specific impact of HDOM on the sorption of organic pollutants on soil and provide new insights into the understanding of the environmental behavior of hydrochar.
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Potential reuse of dewatered sludge (DS) and municipal solid waste incineration (MSWI) bottom ash as components to develop controlled low-strength material (CLSM) was explored. The effects of DS:MSWI bottom ash:calcium sulfoaluminate (CS¯A) cement ratio and thermal treatment of MSWI bottom ash at 900 °C on the mechanical and microstructural properties of CLSM were intensively studied to optimize the process. Results showed DS and MSWI bottom ash could be utilized for making CLSM. The CLSM prepared with milled MSWI bottom ash gave higher unconfined compressive strength (UCS) of 2.0-6.2 MPa following 1 year of curing at 1.0:0.1:0.9 ≤ DS:MSWI bottom ash:CS¯A ≤ 1.0:0.8:0.2. However, the corresponding strengths for CLSM containing thermally treated MSWI bottom ash ranged from 0.7 to 4.6 MPa, decreasing 26-65%. The microstructural analysis by X-ray powder diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), as well as scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectroscopy (EDS) revealed that ettringite (C3A·3CS¯·H32, or AFt) crystals were the most important strength-producing constituents which grew into and filled the CLSM matrix pores. Milled MSWI bottom ash addition favored the formation of highly crystalline AFt phases and accordingly enhanced compressive strengths of CLSM specimens. In contrast, thermal treatment at 900 °C produced new phases such as gehlenite (Ca2Al2SiO7) and hydroxylapatite (Ca5(PO4)3(OH)), which deteriorated the pozzolanic activity of bottom ash and caused the strengths to decrease. Leaching tests evidenced that leachable substances from CLSM samples exhibited negligible health and environmental risks. The results of this study suggested that MSWI bottom ash can be effectively recycled together with DS in developing CLSM mixtures with restricted use of CS¯A cement.
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Cinza de Carvão/química , Reciclagem/métodos , Esgotos/química , Resíduos Sólidos/análise , Cinza de Carvão/análise , Incineração , Microscopia Eletrônica de Varredura , Difração de Pó , Eliminação de Resíduos , Esgotos/análise , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
To assess the potential of ferric hydroxide (FH) to reduce odour emission from dewatered sewage sludge with a moisture of approximately 86%, odour reduction was evaluated using an electronic nose and measurements of odorous compounds (hydrogen sulphide, ammonia and volatile fatty acids (VFAs)). The sulphur species including sulphate, acid-volatile sulphide (AVS), Cr(II)-reducible sulphide (CRS) and elemental sulphur (ES), were analysed by a modified cold diffusion sequential extraction method before and after anaerobic incubation. Within 32 days, 69.3, 83.8 and 88.6% of the odour (or 81.3, 93.7 and 97.5% of hydrogen sulphide) were eliminated, respectively, at the rates of 0.05, 0.10 and 0.25% (wt) of FH. The sulphur species analysis indicated that FeS, FeS2 and a small portion of S0 were formed by FH-sulphide reaction. This study also found that the relationship between odour and H2S concentrations could be well expressed by Steven's law. We believe that FH can be a cost-effective reagent for sludge odour control in sewage treatment processes.
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Compostos Férricos/química , Odorantes/prevenção & controle , Esgotos/química , Amônia/análise , Ácidos Graxos Voláteis/análise , Sulfeto de Hidrogênio/análise , Sulfeto de Hidrogênio/química , Fósforo/análiseRESUMO
Mature landfill leachate (MLL) would be a tough nut to crack, how to realize waste reclamation while deal with the intractable by-products deserves for more considerations. In this study, a novel system, equipped with two biological trickle reactors developed by inert wastes and a connected organic feeder using waste-recycling rotten banana powder, was established for treating MLL. Results indicated that superior pollutant removal performance and long-term stability were achieved by this system, with only COD and TN concentrations slightly higher than the relevant standard limits. But the shortage about poor resistance to shock pollution loads, was underlined by the fluctuation of water quality. Anaerobic condition and carbon source supplementation contributed to more microbial similarities but less community richness and diversity among inert fillings, and the selective enrichment of denitrification and organic-degrading strains simultaneously occurred. The comparisons with common processes demonstrated that this system was a cost-efficient choice for MLL treatment.
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Eliminação de Resíduos , Poluentes Químicos da Água , Resíduos Sólidos/análise , Poluentes Químicos da Água/análise , Reatores Biológicos , Custos de Cuidados de Saúde , Carbono , Instalações de Eliminação de Resíduos , Eliminação de Resíduos/métodosRESUMO
The properties of leachate from refuse transfer stations (RTSs) in rural China were indefinite. In this study, a total of 14 leachate samples from RTSs in nine provinces of China were characterized for their pH, electric conductivity, chromaticity, concentration of organic substances, nitrogen distribution, volatile organic compounds (VOCs), organic phosphorous pesticide, and heavy metals. The structural composition of fluorescent dissolved organic matter (FDOM) was also determined. To evaluate the leachate pollution potential in this study, a leachate pollution index was derived and used. Chromium (Cr) was the most polluting heavy metal present in rural leachate. Ethanol and ethyl acetate were the most frequently detected VOCs at high concentrations. Three-dimensional fluorescence excitation-emission matrix spectra were used to characterize the FDOM. Three components, tryptophan (C1), tyrosine-like (C2), and humic acid- and fulvic acid-like (C3) substances, were identified from all 14 samples. Tryptophan was the major component of FDOM and present in 45.7% of the samples by calculating the fluorescence intensity percentage, on average. Pearson correlations revealed that the fluorescence intensity of C1 and C3 was strongly related to soluble chemical oxygen demand and dissolved oxygen carbon, while C2 had significant positive correlations with ammonia nitrogen and total phosphorus of the solid waste. This study provided detailed data and findings that could serve as a preliminary basis for broadening options for the treatment and management of leachate from rural RTSs in China.
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Metais Pesados , Compostos Orgânicos Voláteis , Triptofano , Análise da Demanda Biológica de Oxigênio , Matéria Orgânica Dissolvida , China , Nitrogênio/análise , Espectrometria de Fluorescência/métodos , Substâncias Húmicas/análise , Análise FatorialRESUMO
In real-field soil conditions, multiple chemicals exposure may be the real scenario for soil biota. The co-occurrence of microplastics (MPs) and cadmium (Cd) is common in soils, which may pose a potential risk to soil ecosystems. Degradable microplastics are producing more MPs, and the potential effects on soil ecosystems are unknown. Therefore, a standard soil animal collembolan Folsomia candida was used to evaluate the single and interaction effects of biodegradable MPs (PLA) and Cd. The results showed that single and co-biodegradable PLA and Cd all had negative influences on the survival, reproduction, and growth of F. candida, and the effects intensified with PLA concentrations. The survival rate, reproduction rate, adult body length, and juvenile body length decreased by 20.0%, 24.2%, 22.9%, and 32.2% at MPs-100 treatment. But combined PLA and Cd alleviated the toxicity of single Cd on F. candida at lower PLA concentrations. The number of juveniles increased by 29.3%, the survival rate increased by 7.52%, the adult body length increased by 11.7%, and the juvenile body length increased by 19.0% at MPs-1 + Cd than single Cd treatment. Biochemical assays on antioxidant enzymes had the same results. Antioxidant enzymes CAT and POD were more sensitive than SOD. CAT and POD activities were induced quickly at shorter exposure periods, and MP treatment thus may be promising biomarkers on soil collembolan for soil MP exposure. PLA is degraded with time in soils; therefore, the long-term effects of co-MPs and Cd in soils are suggested to be further studied.
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Artrópodes , Poluentes do Solo , Animais , Cádmio/análise , Microplásticos , Plásticos/toxicidade , Solo , Antioxidantes/metabolismo , Ecossistema , Poliésteres/farmacologia , Poluentes do Solo/análiseRESUMO
Strong oxidants can reduce the emission of NH3 during composting. But as a commonly used oxidant, the influence of persulfate on nitrogen transformation during composting is unclear. In this study, the effects of 0.3 %-1.2 % potassium persulfate (PS) on nitrogen losses and microbial community during air-dried cow manure composting were investigated. The results showed that PS could reduce nitrogen losses compared to the control. This was because it decreased pH and the maximum NH4+-N content of treatments, which was beneficial to nitrogen retention. In addition, Pseudoxanthomonas and Chelativorans were enriched compared to the control, which might be associated with NH4+-N transformation and nitrogen fixation. Meanwhile, PS increased the abundance of thermophilic lignocellulose degrading bacteria, and 0.3 % and 0.6 % PS increased the maximum temperature and the duration of the thermophilic period. This study indicated that PS could reduce nitrogen losses in composting and greatly influence nitrogen transforming and lignocellulose degrading bacteria.
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Compostagem , Microbiota , Animais , Bovinos , Feminino , Esterco/microbiologia , Nitrogênio/análise , Oxidantes , Compostos de Potássio , Solo , Sulfatos , Zea maysRESUMO
Refuse transfer station (RTS) leachate treatment call for efficient methods to increase nutrient recovery (NH4 +-N and PO4 3--P) and chemical oxygen demand (COD) removal. In this study, the effects of various operational factors (seeding dose, pH, initial NH4 +-N concentration, and reaction time) on biochar-seeded struvite precipitation were investigated at laboratory and pilot scales. Mealworm frass biochar (MFB) and corn stover biochar (CSB) were used as seeding materials to compare with traditional seed struvite. The maximum NH4 +-N and PO4 3--P recover efficiency of the MFB-seeded process reached 85.4 and 97.5%, higher than non-seeded (78.5 and 88.0%) and CSB-seeded (80.5 and 92.0%) processes and close to the struvite-seeded (84.5 and 95.1%) process. The MFB-seeded process also exhibited higher COD removal capacity (46.4%) compared to CSB-seeded (35.9%) and struvite-seeded (31.2%) processes and increased the average particle size of the struvite product from 33.7 to 70.2 µm for better sustained release. XRD, FT-IR, and SEM confirmed the orthorhombic crystal structure with organic matter attached to the struvite product. A pilot-scale test was further carried out in a custom-designed stirred tank reactor (20 L). In the pilot-scale test, the MFB-seeded process still spectacularly recovered 77.9% of NH4 +-N and 96.1% of PO4 3--P with 42.1% COD removal, which was slightly lower than the laboratory test due to insufficient and uniform agitation. On the whole, MFB-seeded struvite precipitation is considered to be a promising pretreatment method for rural RTS leachate.
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Biochar has attracted great interest in both CO2 capture and supercapacitor applications due to its unique physicochemical properties and low cost. Fabrication of eco-friendly and cost-effective biochar from high potential biomass Tenebrio molitor feces can not only realize the functional application of waste, but also a potential way of future carbon capture and energy storage technology. In this study, a novel KOH activation waste-fed Tenebrio molitor feces biochar (TMFB) was developed and investigated in terms of CO2 capture and electrochemical performance. When activated at 700 °C for 1 h, the specific surface area of the feces biochar (TMFB-700A) increased significantly from 232.1 to 2081.8 m2 g-1. In addition, well-developed pore distribution facilitates CO2 capture and electrolyte diffusion. TMFB-700A can quickly adsorb a large amount of CO2 (3.05 mol kg-1) with excellent recycling performance. TMFB-700A also exhibited promising electrochemical performance (335.8 F g-1 at 0.5 A g-1) and was used as electrode material in a symmetrical supercapacitor. It provided a high energy density of 33.97 W h kg-1 at a power density of 0.25 kW kg-1 with 90.47% capacitance retention after 10 000 charge-discharge cycles. All the results demonstrated that TMFB could be a potential bifunctional material and provided valuable new insights for Tenebrio molitor feces high-value utilization.
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Fluorescence excitation-emission matrix (EEM) spectroscopy is a powerful tool to characterize DOM that interacts with heavy metals in MSWI bottom ash (IBA). Here, two fresh IBA samples collected from large MSWI plants were subjected to 33 days of accelerated weathering. Carbon content and fluorescence characterization of DOM and leaching behavior of heavy metals (Cu, Ba, Cr, Ni, and oxyanions) were monitored during the weathering. The mineralogical and chemical properties of IBA during the weathering process were also characterized. EEM combined with parallel factor analysis showed that fluorescent DOM could be decomposed into humic-like (C1, C2) and tryptophan-like substances (C3), while the accelerated weathering process can be further divided into three phases. Fitted cubic polynomials described well the changes in the specific intensity of fluorescence components. Humification and freshness indexes and SUVA results suggested the leached DOM contained a higher proportion of condensed aromatic structures and/or conjugation of aliphatic chains post-weathering. The results also revealed that adsorption of humic-like substances onto neo-formed reactive surfaces occurred quickly in the early stage of accelerated weathering; thereafter, biodegradation of lower molecular mass-hydrophilic organic carbon fraction plays a vital role in further reduction of Cu and Cr leaching in subsequent weathering. Oxyanions (Mo and Sb) became more mobile after 3 days of accelerated weathering, but their leaching was effectively reduced after the weathering process. A novel method for an IBA weathering treatment combined with enhanced microbial degradation is proposed. These findings provide new and inspiration for improving accelerated weathering technology.
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Cinza de Carvão , Metais Pesados , Carbono , Análise Fatorial , Substâncias Húmicas/análise , Espectrometria de Fluorescência/métodosRESUMO
As a natural source of visible light and a type of renewable energy, solar energy is extensively used in the field of photochemistry. In this study, solar was employed to activate persulfate (PS) to degrade typical micropollutants. The removal kinetics of aspirin (ASA) and flunixin meglumine (FMME) in the solar/PS system were well fitted by pseudo-first-order models (R2 > 0.99). In the system containing 1.0 mM PS activated by solar irradiation at a fluence of 1.14 × 10-4 E·m-2·s-1, 72.6% and 97.5% of ASA and FMME were degraded, and the corresponding kinetic constants were 6.8-9.8 × 10-2 and 1.6-9.8 × 10-1 min-1, respectively. Qualitative and quantitative analyses of the reactive oxygen species (ROS) indicated that sulfate radical (SO4·-) played a major role in degradation, with the maximum contributions of 77.7% and 88.8% for the degradation of ASA and FMME, whereas the maximum contributions of hydroxyl radical (·OH) were only 11.6% and 6.5%, respectively. The contributions of singlet oxygen (1O2) were less than 15% at pH 5.5, but increased to 25.6% and 45.5% at pH 8.5, respectively. Solar/PS pre-oxidation increased disinfection byproducts (DBPs) (95.8% for trihalomethanes (THMs) and 47.9% for haloacetic acids (HAAs) at pH 7.0) after chlorination in deionized water, and an opposite trend was found in systems coexisting with natural organic matter (NOM). Residual PS after oxidation resulted in a high aquatic toxicity, with an inhibition rate of 18.70% to algae growth. Economic analysis showed that the electrical energy per order values of the system ranged from 23.5 to 86.5 kWh·m-3·order-1, indicating that the solar/PS system shows promise for practical applications.
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Poluentes Químicos da Água , Purificação da Água , Desinfecção , Estudos de Viabilidade , Espécies Reativas de OxigênioRESUMO
The effects of FeSO4 on nitrogen loss and humification were investigated in the composting of cow dung and corn straw. The results showed that all groups met the ripening requirements after 50 days: the temperature was above 50 °C for 12- 17 days; the products had pH values of 6.4-7.6, electrical conductivities of 1.06-1.33 ms·cm-1, NH4+-N contents of 37.2-61.8 mg kg-1, and the seed germination index of 95%-101%. FeSO4 reduced nitrogen losses by 9.21-15.65% compared to the control group. FeSO4 also improved the compost humification process: the humus substances (HS) contents in the compost product with FeSO4 were 109.82-129.86 g·kg-1, higher than 106.31 g·kg-1 in the control group. The compost product in 3.75% FeSO4 treatment had the highest maturity degree. This study showed that FeSO4 could inhibit the mineralization of organic matter during the composting and accelerate the formation of HS.
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Compostagem , Animais , Bovinos , Nitrogênio , Solo , Temperatura , Zea maysRESUMO
Acetaminophen (ACT) and phenacetin (PNT) removal during light-emitting diode (LED)-UV photolysis of persulfate (PS) was evaluated with a typical wavelength of 365 nm. Decay of PNT and ACT in pH ranges of 5.5-8.5 followed pseudo-first order kinetics. Maximum pseudo-first order rate constants (kobs) of ACT and PNT decomposition of 1.8 × 10-1 and 1.2 × 10-1 min-1, respectively, were obtained at pH 8.5. Hydroxyl radicals (·OH), sulfate radicals (SO4·-), superoxide radicals (O2-·), and singlet oxygen (1O2) were determined in-situ electron paramagnetic resonance (EPR) and alcohol scavenging tests. The average contributions of ·OH and SO4·- were 23.5% and 53.0% for PNT removal, and 15.9% and 53.0% for ACT removal at pH ranges of 5.5-8.5. In samples subjected to chlorination after LED-UV365/PS pre-oxidation, a relatively small total concentration of five halogenated disinfection by-products (DBPs) was obtained of 90.9 µg L-1 (pH 5.5) and 126.7 µg L-1 (pH 7.0), which is 58.5% and 30.2% lower than that in system without LED-UV365/PS pre-oxidation. Meanwhile, a higher maximum value of total DBP concentration was obtained at pH 8.5 (445.6 µg L-1) following LED-UV365/PS pre-oxidation. The results of economy evaluation showed that UV365 was more cost-effective in application for organic contaminant removal compared with UV254.
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Poluentes Químicos da Água , Purificação da Água , Acetaminofen , Cinética , Oxirredução , Fenacetina , Fotólise , Espécies Reativas de Oxigênio , Raios Ultravioleta , Poluentes Químicos da Água/análiseRESUMO
Fluorescence excitation-emission matrix (EEM) spectroscopy is a powerful tool for characterizing dissolved organic matter (DOM), a key component of anaerobic digestion. In this study, the fluorescence characteristics of DOM during 55 days of anaerobic digestion of oil crop straw inoculated with rumen liquid were investigated. EEM spectroscopy coupled with parallel factor analysis (PARAFAC) showed that three major fluorescence components, tyrosine- (C1), humic- (C2) and tryptophan-like substances (C3), were identified in all DOM samples. The F max values of C1 and C3 increased rapidly during the first 5 d, decreased dramatically from day 5 to day 35, and then remained stable, while C2 was not biodegraded. The changes in the F max values of the fluorescence components reflected the biodegradation of lignin and/or embedded cellulose by rumen microorganisms. The changes in the Stokes shift of the fluorescence peak were readily explained by the variation in the hydrophobic/hydrophilic fraction distribution. The humidification index (HIX) and A : T ratio of the DOM decreased after 5 d and then increased gradually. Compared with the McKnight fluorescence index (MFI), the Y fluorescence index (YFI) was better able to track the evolution of the DOM. Correlation analysis of the different fluorescence indices (intensities) and absorbance indices was also carried out. The EEM-PARAFAC individual components, HIX and A : T ratio were conveniently used to characterize the degree of anaerobic conversion of the organic matter, and the peak at the Stokes shift of â¼1.0 µm-1 was used as one of the indicators showing the stabilization of anaerobic digestion. These findings may assist in developing fluorescence technology for monitoring the anaerobic digestion of crop straw.
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Phosphate-solubilizing (PS) microbes are important to improve phosphorus availability and transformation of insoluble phosphate, e.g., rock phosphate (RP). The use of phosphate solubilizing bacteria (PSB) as inoculants have been proposed as an alternative to increase phosphate availability in RP and composting fertilizers. In this study, the effect of compound PSB coinoculation and single-strain inoculation on the transformation of insoluble phosphate were compared in a liquid medium incubation and RP-enriched composting. The goal of this study was to understand the possible mechanisms of insoluble phosphate transformation driven by the interactions of compound PS microbes during composting. The correlations between organic acids production, P-solubilization capacity and bacterial community with PSB inoculation were investigated in the RP-enriched composting by redundancy analysis (RDA) and structural equation models (SEM). Results showed that both single-strain and compound PSB inoculants had a high P-solubilization capacity in medium, but the proportion of Olsen P to total P in composts with inoculating compound PS microbes was 7% higher than that with single strain. PS inoculants could secrete different organic acids and lactic was the most abundant. However, RDA and SEM suggested that oxalic might play an important role on PS activity, inducing RP solubilization by changing pH during composting. Interaction between compound microbes could intensify the acidolysis process for insoluble P transformation compared to the single strain. Our findings help to understand the roles of complex microbial inoculants and regulate P availability of insoluble phosphate for the agricultural purposes.