Preparation, characterization, and phenol adsorption of activated carbons from oxytetracycline bacterial residue

Rapid and efficient removal of multiple heavy metals from diverse types of water using magnetic biochars derived from antibiotic fermentation residue

Pyrolysis is a promising method to treat antibiotic fermentation residue (AFR), a hazardous waste in China, with the benefits of detoxification and resource recycling. However, the application of the AFR-derived biochar has been limited yet, restricting the use of pyrolysis to treat AFR. Herein, for the first time, we reported the use of magnetic biochars derived from vancomycin fermentation residue to rapidly and efficiently co-adsorb multiple heavy metals from diverse types of water with complex matrices. The biochar prepared at 700 °C (labeled as VBC700) exhibited high affinity and selectivity for multiple heavy metals, especially for Ag(I), Hg(II), Pb(II), and Cu(II). The kinetics for Ag(I), Hg(II), and Pb(II) were ultrafast with an equilibrium time of only 5 min, while those for Cu(II) were relatively slower. The maximum adsorption capacity calculated from the Langmuir model for Ag(I), Hg(II), Pb(II), and Cu(II) reached 177.4, 105.9, 387.1, 124.5 mg/g, respectively, which were superior to much previously reported adsorbents. Impressively, Na(I), K(I), Ca(II), Mg(II), and salinity did not affect the capture of these heavy metals, and thus >99% of Ag(I), Pb(II), and Cu(II) were concurrently removed from complex water matrices including seawater, which has rarely been reported before. Furthermore, VBC700 remained high adsorption performance at pH ≥ 3. The adsorption mechanisms included ion exchange, precipitation, and inner-sphere complexation. Overall, the results demonstrate that VBC700 would be an excellent adsorbent to co-capture multiple heavy metals from diverse types of water, highlighting the feasibility of using pyrolysis to achieve a win-win goal for AFR management and heavy metal pollution control.

Effects of demineralization and devolatilization on fast pyrolysis behaviors and product characteristics of penicillin mycelial residues

In this study, the effects of demineralization and devolatilization methods including of water washing (WW), torrefaction (TF), washing-torrefaction (WT) and hydrothermal treatment (HT) on the fast pyrolysis characteristics of penicillin mycelial residues were studied. The materials and pyrolysis products were characterized by analysis methods including of thermogravimetric (TG), gas chromatograph (GC), gas chromatography-mass spectrometry (GC-MS), x-ray diffractometer (XRD), fourier transform-infrared spectroscopy (FT-IR) and x-ray photoelectron spectroscopy (XPS), etc. The results showed WW increased the yields of tar and decreased the yields of pyrolysis biochar due to the removal of alkali and alkaline earth metals (AAEMs), while TF and HT showed opposite results due the devolatilization. XPS and FT-IR results proved that the conversion from aliphatic C-(C, H) to aromatic groups C-O-C and CO was the key point for improving the aromatization of biochar. Pretreatments increased the relative proportions of N-containing heterocyclic compounds and phenolic compounds, reduced the proportions of O-containing heterocyclic compounds in pyrolysis tar. And TF and HT could eliminate the residual antibiotic and satisfy the principle of AMR harmless disposal.

Black Soldier Fly Larvae Can Effectively Degrade Oxytetracycline Bacterial Residue by Means of the Gut Bacterial Community

Antibiotic bacterial residue is a unique hazardous waste, and its safe and effective disposal has always been a concern of pharmaceutical enterprises. This report presents the effective treatment of hazardous waste-antibiotic bacterial residue-by black soldier fly larvae (larvae), oxytetracycline bacterial residue (OBR), and soya meal with mass ratios of 0:1 (soya), 1:20 (OBRlow), and 1:2 (OBRhigh), which were used as substrates for larval bioconversion. Degradation of OBR and oxytetracycline, the bacterial community, the incidence of antibiotic resistance genes (ARGs) and the bacterial function in the gut were examined. When the larvae were harvested, 70.8, 59.3, and 54.5% of the substrates had been consumed for soya, OBRlow and OBRhigh; 65.9 and 63.3% of the oxytetracycline was degraded effectively in OBRlow and OBRhigh, respectively. The larval bacterial communities were affected by OBR, abundant and various ARGs were discovered in the gut, and metabolism was the major predicted function of the gut. These findings show that OBR can be digested and converted by larvae with gut bacteria, and the larvae can be used as a bioremediation tool for the treatment of hazardous waste. Finally, the abundant ARGs in the gut deserve further attention and consideration in environmental health risk assessments.

Conversion of phosphorus and nitrogen in lincomycin residue during microwave-assisted hydrothermal liquefaction and its application for Pb2+ removal

Treatment of antibiotic fermentative residue (AFR) produced from pharmaceutical industries and their application in the environment has been gaining researchers' interest. In this study, lincomycin residue (LMR, the type of AFR) was treated with microwave-assisted hydrothermal liquefaction (MW-HTL) in a temperature range 120-210 °C, transforming effect of phosphorus (P) and nitrogen (N) functional groups in LMR samples was characterized with elemental analysis, XRD, XPS, FT-IR, and P-extraction, and utilized LMR samples for Pb²⁺ removal from aqueous solutions. The temperature had a significant impact on P and N functional groups conversion justified by characterization techniques and also responsible for Pb²⁺ adsorption. LMR hydrochar produced at 210 °C was accounted highest Pb²⁺ adsorption capacity (57.4 mg g^-1), higher four folds than raw LMR (13.8 mg g^-1). To understand the mechanism and rate defining phase of adsorption equilibrium isotherm and kinetic models were applied systematically. Adsorption results of LMR and its derived hydrochar samples found connectivity with Langmuir and pseudo-first-order isotherm models. Adsorption mainly occurred as ion-exchange dependent on the substitution of metal ions (Pb²⁺) to Ca²⁺ ions present in P-materials, and surface adsorption dependent on surface functional groups of LMR samples. Better operation feasibility of MW-HTL treated LMR, elaboration of P and N conversion behavior and high sorption of Pb²⁺ ions could make LMR a frontrunner for heavy metals immobilization.

Removal behaviors and mechanisms of hexavalent chromium from aqueous solution by cephalosporin residue and derived chars

Cephalosporin residue (CR) was used to produce biochar (BC) and activated carbon (AC) at 600°C (BC600 and AC600). To compare the removal behaviors and mechanisms of Cr(VI) by CR and derived chars, batch adsorption tests were performed in Cr(VI) microenvironment like pH, Cr(VI) concentration, adsorbent dosage, combing with the characterization of adsorbents before and after adsorption. Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) techniques were used. Results showed that the Cr(VI) removals by CR and CR-chars fitted Freundlich and Langmuir models. Based on the Langmuir model, the maximum adsorption capacities of CR, BC600 and AC600 towards Cr(VI) were 107.41, 88.19 and 74.07mgg^-1, respectively. The CR rich in dissolved carbon (DOC), -NH₂ and -COOH, chiefly acted as chelating and reducing agents, while the AC600 with high surface area mainly supported Cr(VI) adsorption during Cr(VI) removal process.

Anaerobic digestion of thermal-alkaline-pretreated cephalosporin bacterial residues for methane production

Optimum anaerobic conditions of cephalosporin bacterial residues after thermal-alkaline pretreatment were determined by orthogonal experiments. And through biochemical methane potential tests (BMPs) for cephalosporin bacterial residues, the ability for bacterial degradation of cephalosporin was also evaluated. The thermal-alkaline pretreatment with the optimum values of 6% NaOH at 105 °C for 15 min significantly improved digestion performance. With the thermal-alkaline pretreatment, the specific methane yield of the pretreated cephalosporin bacterial residue increased by 254.79% compared with that of the un-pretreated cephalosporin bacterial residue. The results showed that anaerobic digestion of thermal-alkaline-pretreated cephalosporin bacterial residues could be one of the options for efficient methane production and waste treatment.

IMPLICATIONS

This work investigates the thermal-alkaline pretreatment of cephalosporin bacterial residues, which can increase their methane yield by 254.79% compared with no pretreatment. The digestion performance is significantly improved under the condition of 6% NaOH at 105 °C for 15 min. The results show that anaerobic digestion of thermal-alkaline-pretreated cephalosporin bacterial residues could be one of the options for efficient methane production and waste treatment.

Tracking the conversion of nitrogen during pyrolysis of antibiotic mycelial fermentation residues using XPS and TG-FTIR-MS technology

Antibiotic mycelial fermentation residues (AMFRs), which are emerging solid pollutants, have been recognized as hazardous waste in China since 2008. Nitrogen (N), which is an environmental sensitivity element, is largely retained in AMFR samples derived from fermentation substrates. Pyrolysis is a promising technology for the treatment of solid waste. However, the outcomes of N element during the pyrolysis of AMFRs are still unknown. In this study, the conversion of N element during the pyrolysis of AMFRs was tracked using XPS (X-ray photoelectron spectroscopy) and online TG-FTIR-MS (Thermogravimetry-Fourier transform infrared-Mass spectrometry) technology. In the AMFR sample, organic amine-N, pyrrolic-N, protein-N, pyridinic-N, was the main N-containing species. XPS results indicated that pyrrolic-N and pyridinic-N were retained in the AMFR-derived pyrolysis char. More stable species, such as N-oxide and quaternary-N, were also produced in the char. TG-FTIR-MS results indicated that NH3 and HCN were the main gaseous species, and their contents were closely related to the contents of amine-N and protein-N, and pyrrolic-N and pyridinic-N of AMFRs, respectively. Increases in heating rate enhanced the amounts of NH3 and HCN, but had less of an effect on the degradation degree of AMFRs. N-containing organic compounds, including amine-N, nitrile-N and heterocyclic-N, were discerned from the AMFR pyrolysis process. Their release range was extended with increasing of heating rate and carbon content of AMFR sample. This work will help to take appropriate measure to reduce secondary pollution from the treatment of AMFRs.

Combustion of hazardous biological waste derived from the fermentation of antibiotics using TG-FTIR and Py-GC/MS techniques

The combustion characteristics for three kinds of antibiotics residue (AR) materials were investigated by TG-FTIR and Py-GC/MS technique. The TG results indicated that AR combustion involved three stages, and correlation between the H/C atomic ratio of the raw materials and peak temperature of weight loss for the second stage was obtained. The FTIR spectra identified evolving gaseous products as CO2, CH4, HCNO, NH3, HCN, and NO. An AR material with a low H/C ratio promoted the formation of CO2 and HCN, but suppressed the yields of NH3 and CH4. The Py-GC/MS results suggested that abundant volatiles can be produced, including alkenes, benzene, phenols, furans, acid, and heterocyclic-N, nitrile-N and amine-N compounds, and confirmed the FTIR absorption characteristics in the low temperature range. A possible pathway for the AR combustion was also tentatively presented.

Adsorption and oxidation of SO₂in a fixed-bed reactor using activated carbon produced from oxytetracycline bacterial residue and impregnated with copper

The SO₂removal ability (including adsorption and oxidation ability) of activated carbon produced from oxytetracycline bacterial residue and impregnated with copper was investigated. The activated carbon produced from oxytetracycline bacterial residue and modified with copper was characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The effects of the catalysts, SO₂concentration, weight hourly space velocity, and temperature on the SO₂adsorption and oxidation activity were evaluated. Activated carbon produced from oxytetracycline bacterial residue and used as catalyst supports for copper oxide catalysts provided high catalytic activity for the adsorbing and oxidizing of SO₂from flue gases.