Erythromycin Removal Research Articles

Antibiotic Removal by Three Promising Microalgae Strains: Biotic, Abiotic Routes, and Response Mechanisms

Microalgae represent an alternative to conventional wastewater treatment, potentially improving antibiotic removal and offering a solution to combat the spread of antimicrobial resistance. Through batch assays, this study investigates the routes for antibiotic removal using three strains (Chlamydomonas acidophila, Auxhenochlorella protothecoides and Tetradesmus obliquus). Using mixtures of ciprofloxacin, clarithromycin, erythromycin, metronidazole, ofloxacin, sulfamethoxazole, and trimethoprim at concentrations simulating wastewater composition, it also assesses antibiotic effects on microalgae physiology. The three strains primarily removed antibiotics through rapid biosorption, achieving up to 91.5% removal for specific ones like ciprofloxacin. T. obliquus and C. acidophila showed efficacy, with total removals of 37.2% and 49.3%, respectively. Over time, A. protothecoides demonstrated the highest active removal efficiency, eliminating 22.1% of total antibiotics, with a notable 67.6% removal for sulfamethoxazole. Abiotic degradation through hydrolysis and photolysis contributed to ciprofloxacin, ofloxacin, clarithromycin, and erythromycin removal (34.7% to 96.7%), showing pH-dependent photolysis. However, algae induced a shading effect, reducing the photolytic and hydrolytic degradation of specific antibiotics. T. obliquus and C. acidophila were inhibited by antibiotics, whereas A. protothecoides showed a 30.6% growth rate increase. The stimulatory effect was also observed for the nutrient removal, with A. protothecoides showing a 46.6% increase in ammonium removal and a 44.8% increase in phosphate removal with antibiotics. Additionally, antioxidant activities remained stable, except for a notable increase in peroxidase activity for A. protothecoides and T. obliquus. The study confirms efficient antibiotic removal and stimulatory responses in the three algal strains, indicating their potential for wastewater treatment and combating antimicrobial resistance.

Effect of Stepwise Exposure to High-Level Erythromycin on Anaerobic Digestion.

High-level erythromycin (ERY) fermentation wastewater will pose serious threats to lake environments. Anaerobic digestion (AD) has advantages in treating high-level antibiotic wastewater. However, the fate of antibiotic resistance genes (ARGs) and microbial communities in AD after stepwise exposure to high-level ERY remains unclear. In this study, an AD reactor was first exposed to 0, 5, 10, 50, 100 and 200 mg/L ERY and then re-exposed to 0, 50, 200 and 500 mg/L ERY to investigate the effect of ERY on AD. The results show that AD could adapt to the presence of high-level ERY (500 mg/L) and could maintain efficient CH4 production after domestication with low-level ERY (50 mg/L). The AD process could achieve higher removal of ERY (>94%), regardless of the initial ERY concentration. ErmB and mefA, conferring resistance through target alteration and efflux pumps, respectively, were dominant in the AD process. The first exposure to ERY stimulated an increase in the total ARG abundance, while the AD process seemed to discourage ARG maintenance following re-exposure to ERY. ERY inhibited the process of acetoclastic methanogenesis, but strengthened the process of hydrogenotrophic methanogenesis. This work provides useful information for treating high-level ERY fermentation wastewater by the AD process.

Removal of Erythromycin from Water by Ibuprofen-Driven Pre-Organized Divinyl Sulfone Cross-Linked Dextrin.

Water recycling and reuse are cornerstones of water management, which can be compromised by the presence of pollutants. Among these, pharmaceuticals can overcome standard water treatments and require sophisticated approaches to remove them. Sorption is an economically viable alternative limited by the need for sorbents with a sorption coefficient (Kd) higher than 500 L/kg. The cross-linking of dextrin (Dx) with divinyl sulfone (DVS) in the presence of 1 mmol or 5 mmol of ibuprofen (IBU) yields the insoluble polymers pDx1 and pDx5 with improved affinity for IBU and high selectivity towards erythromycin (ERY) and ERY Kd higher than 4 × 103 L/kg, when tested against a cocktail of six drugs. Characterization of the polymers shows that both pDx1 and pDx5 have similar properties, fast sorption kinetics, and ERY Kd of 13.3 × 103 for pDx1 and 6.4 × 103 for pDx5, representing 26.6 and 12.0 times the 500 L/kg threshold. The fact that new affinities and improvements in Kd can be achieved by cross-linking Dx in the presence of other molecules that promote pre-organization expands the applications of DVS cross-linked polysaccharides as sustainable, scalable, and environmentally friendly sorbents with a potential application in wastewater treatment plants (WTPs).

Volatile fatty acids recovery and antibiotic degradation from erythromycin fermentation residues by combined thermal pretreatment and anaerobic fermentation: Insights into microbial communities and metabolic pathways

High resistance of erythromycin has been the key factor restricting the disposal of erythromycin fermentation residues (EFR). Considering the high sensitivity of erythromycin to acidic conditions, anaerobic fermentation may be a good approach for EFR treatment, through which pH decreases along with the volatile fatty acids (VFA) accumulation. This study firstly explored the EFR treatment by combined thermal pretreatment and anaerobic fermentation. Results showed that thermal pretreatment and anaerobic fermentation exhibited a synergistic effect on erythromycin removal. Erythromycin concentration decreased to 20.0 mg/L with the maximum removal rate of 60.0%, which was 140% and 71.4% higher than erythromycin removal by sole thermal pretreatment and anaerobic fermentation. Thermal pretreatment induced the increased VFA production by 22.3% with the highest VFA concentration of 5325.4 mg/L. Microbial analysis shows that thermal pretreatment stimulated erythromycin degradation and VFA production by increasing the microbial diversity and enriching the functional enzymes involved in acetate-producing pathways.

Combined toxicity of erythromycin and roxithromycin and their removal by Chlorella pyrenoidosa

The ecological effects of antibiotics in surface water have attracted increasing research attention. In this study, we investigated the combined ecotoxicity of erythromycin (ERY) and roxithromycin (ROX) on the microalgae, Chlorella pyrenoidosa, and the removal of ERY and ROX during the exposure. The calculated 96-h median effect concentration (EC50) values of ERY, ROX, and their mixture (2:1 w/w) were 7.37, 3.54, and 7.91 mg∙L-1, respectively. However, the predicted EC50 values of ERY+ROX mixture were 5.42 and 1.51 mg∙L-1, based on the concentration addition and independent action models, respectively. This demonstrated the combined toxicity of ERY+ ROX mixture showed an antagonistic effect on Chlorella pyrenoidosa. During the 14-d culture, low-concentration (EC10) treatments with ERY, ROX, and their mixture caused the growth inhibition rate to decrease during the first 12 d and increase slightly at 14 d. In contrast, high-concentration (EC50) treatments significantly inhibited microalgae growth (p < 0.05). Changes in the total chlorophyll contents, SOD and CAT activities, and MDA contents of microalgae suggested that individual treatments with ERY and ROX induced higher oxidative stress than combined treatments. After the 14-d culture time, residual Ery in low and high concentration Ery treatments were 17.75% and 74.43%, and the residual Rox were 76.54% and 87.99%, but the residuals were 8.03% and 73.53% in ERY+ ROX combined treatment. These indicated that antibiotic removal efficiency was higher in combined treatments than that in individual treatments, especially at low concentrations (EC10). Correlation analysis suggested that there was a significant negative correlation between the antibiotic removal efficiency of C. pyrenoidosa and their SOD activity and MDA content, and the enhanced antibiotic removal ability of microalgae benefited from increased cell growth and chlorophyll content. Findings in this study contribute to predicting ecological risk of coexisting antibiotics in aquatic environment, and to improving biological treatment technology of antibiotics in wastewater.

Membrane fouling mechanism of submerged membrane bioreactor during erythromycin removal

Background: Based on the previous studies, antibiotics can have affected biological properties of biomass and fouling properties of mixed liquor in aeration tank. The present study was conducted to explore the fouling mechanisms of membrane bioreactor (MBR) system during the treatment of wastewater containing erythromycin (ERY) antibiotic under several mixed liquor suspended solids (MLSS) concentrations. Methods: A lab-scale two-chamber MBR system equipped with a polypropylene hollow fiber submerged membrane was fed with synthetic wastewater containing different initial concentrations of ERY. MBR system was operated under the constant flux mode and different MLSS concentrations (5.0-13.0 g/L) and the obtained results were evaluated using different individual and combined fouling models. Results: The variation of MLSS concentrations had not significantly affected the kind of best-fitted model. From the individual models, the standard model indicated the best performance for permeate prediction under different MLSS concentrations (R2 adj&gt;0.997). For all studied MLSS concentrations, the R2 adj values of combined fouling models were higher than 0.986 and demonstrated good fitness performance of combined models compared to individual models. Overall, the cake-intermediate model showed the lowest fitness, and cake-complete and complete-standard models were the most successful models in filtrated volume prediction in comparison with other combined fouling models. Conclusion: This study indicated that mechanistic models are suitable for fouling prediction of MBR systems in ERY removal and under a wide range of MLSS concentrations and provide valuable information on fouling mechanisms of full-scale MBR systems.

The Removal of Erythromycin and Its Effects on Anaerobic Fermentation.

In view of the problems of antibiotic pollution, anaerobic fermentation technology was adopted to remove erythromycin in this study. The removal of erythromycin and its effects mechanism on anaerobic fermentation were studied, including biogas performance, process stability, substrate degradability, enzyme activity, and microbial communities. The results showed that the removal rates of erythromycin for all tested concentrations were higher than 90% after fermentation. Erythromycin addition inhibited biogas production. The more erythromycin added, the lower the CH4 content obtained. The high concentration of erythromycin (20 and 40 mg/L) resulted in more remarkable variations of pH values than the control group and 1 mg/L erythromycin added during the fermentation process. Erythromycin inhibited the hydrolysis process in the early stage of anaerobic fermentation. The contents of chemical oxygen demand (COD), NH4+–N, and volatile fatty acids (VFA) of erythromycin added groups were lower than those of the control group. Erythromycin inhibited the degradation of lignocellulose in the late stage of fermentation. Cellulase activity increased first and then decreased during the fermentation and addition of erythromycin delayed the peak of cellulase activity. The inhibitory effect of erythromycin on the activity of coenzyme F420 increased with elevated erythromycin concentrations. The relative abundance of archaea in erythromycin added groups was lower than the control group. The decrease in archaea resulted in the delay of the daily biogas peak. Additionally, the degradation rate of erythromycin was significantly correlated with the cumulative biogas yield, COD, pH, and ORP. This study supports the reutilization of antibiotic-contaminated biowaste and provides references for further research.

Effect of Hydrothermal Pretreatment on Anaerobic Digestion of Erythromycin Fermentation Dregs: Biogas Production, Antibiotic Resistance Gene Evolution, and Microbial Community Dynamics

The utilization of erythromycin fermentation dregs (EFD), one kind of solid biowaste, is limited due to the high-level residue of antibiotics. Hydrothermal pretreatment (HT) has great potential to remove residual antibiotics. However, its harmless performance and influence on the EFD anerobic digestion (AD) process remains unclear. In this study, HT was conducted for erythromycin removal before EFD AD with the temperature ranging from 80 to 180°C. Moreover, changes in biogas yield, antibiotic resistance genes (ARGs), and microbial communities in the EFD AD process were compared among different treatments. The results showed that under the optimal hydrothermal temperature of 160°C, more than 85% of erythromycin was eliminated. In addition, HT significantly reduced the ARGs in the EFD AD process and ermT and mefA relative abundance decreased by one order of magnitude. Mobile genetic elements (IntI1 and Tn916/1545) also showed decreased tendency with the hydrothermal temperature elevation. The maximum methane production of 428.3 ml g−1 VS was obtained in the AD system of EFD with hydrothermal treatment at 160°C. It is attributed to the cooperation of hydrolysis and acidogenesis bacteria (e.g., Aminicenantales and Sedimentibacter) and methylotrophic methanogens (Candidatus_Methanofastidiosum and Methanosarcina), and they presented the highest relative abundance in this group. The results indicated that methylated substance reduction was the major methanogenesis route. Hydrothermal technology was of great potential to realize the harmless treatment of EFD and for recycling EFD via AD.

Enhanced removal of antibiotics using Eichhornia crassipes root biomass in an aerobic hollow-fiber membrane bioreactor

The impact of water hyacinth (Eichhornia crassipes) root biomass (WHRB) on pharmaceutical wastewater treatment with an aerobic hollow-fiber membrane bioreactor (HF-MBR) was investigated. The performance of the bioreactor was assessed in terms of COD (Chemical Oxygen Demand) and antibiotic removal and membrane biofouling rate. For deeper insight, microbial communities in sludge and biofilm layers were analyzed through Illumina sequencing. The addition of WHRB into the HF-MBR increased the COD (by 6%), as well as antibiotics and transformation products removal efficiency. Removal efficiencies of 97%, 98% and 84% were obtained for removal of erythromycin, sulfamethoxazole, and tetracycline. Furthermore, WHRB modified the biodegradation network, increased the relative abundances of Chloroflexi, Proteobacteria and Nitrospirae and decreased Firmicutes, compared with the control with antibiotics. The addition of WHRB also enriched Actinobacteria and Bacteroidetes while decreasing the phylla Chloroflexi and Saccharibacteria in the biofilm.

Corrigendum: Journal of Water, Sanitation and Hygiene for Development 9 (3), 571–580: Efficacy of integrated ultraviolet ultrasonic technologies in the removal of erythromycin- and quinolone-resistant Escherichia coli from domestic wastewater through a laboratory-based experiment, Owassa Dza Rebecca Annisha, Zifu Li, Xiaoqin Zhou, Ngomah Madgil Don Stenay Junior and Oscar Omondi Donde, https://doi.org/10.2166/washdev.2019.021

Corrigendum: <i>Journal of Water, Sanitation and Hygiene for Development</i> 9 (3), 571–580: Efficacy of integrated ultraviolet ultrasonic technologies in the removal of erythromycin- and quinolone-resistant <i>Escherichia coli</i> from domestic wastewater through a laboratory-based experiment, Owassa Dza Rebecca Annisha, Zifu Li, Xiaoqin Zhou, Ngomah Madgil Don Stenay Junior and Oscar Omondi Donde, https://doi.org/10.2166/washdev.2019.021

Evaluating aquatic macrophytes for removing erythromycin from contaminated water: floating or submerged?

Water contamination by antibiotics is an emerging global problem, with impacts on both public health and the environment. Erythromycin has been encountered in bodies of water throughout the world, which demands the development of efficient remediation technologies. We investigated the physiological responses and phytoremediation capacity of four species of aquatic macrophytes, two floating (Salvinia molesta and Lemna minor) and two submerged (Myriophyllum aquaticum and Rotala rotundifolia). The plants were exposed to relevant environmental concentrations of erythromycin (0 and 1.7 µg l−1) in artificially contaminated water for seven days. Physiological evaluations evidenced the ability of that antibiotic to promote oxidative events in those plants, such as the activation of antioxidant enzymes (ascorbate peroxidase and/or catalase). S. molesta exposed to erythromycin demonstrated accumulations of hydrogen peroxide and oxidative damage (lipid peroxidation) that was reflected in growth reductions. The erythromycin removal efficiency of floating plants varied from 9 to 12%, while submerged species varied from 31 to 44%. As such, submerged macrophyte species demonstrated the most efficient removal of erythromycin from contaminated waters, and are therefore more indicated for antibiotic phytoremediation projects.

Advanced treatment of antibiotic wastewater by ionizing radiation combined with peroxymonosulfate/H2O2 oxidation

The advanced treatment of secondary effluent from an antibiotic wastewater treatment plant was investigated using ionizing radiation alone and combined with peroxymonosulfate (PMS)/H2O2 oxidation. In the effluent, 3 antibiotics, including erythromycin (ERY), tetracycline (TC), sulfamethoxazole (SMX), and 7 groups of antimicrobial resistance genes (ARGs) and 12 bacterial classes were detected. Results showed that the content of antibiotics and ARGs could be reduced greatly by radiation. The removal of ERY, TC and SMX reached 87%, 80% and 48% respectively, while the abatement of ARGs, including ermB, ermT, ermF, maA/mel, sul2, blaOXA, floR and mefA reached 63–91%. The COD removal was only 16.8% at 25 kGy. The enhancement with PMS addition was better than with H2O2 addition during radiation. With 10 mM PMS addition, the removal efficiency of antibiotics and COD increased to 70–98% and 57.6%, compared to 55–97% and 45.1% with 10 mM of H2O2 addition at 25 kGy. The PICRUSt analysis suggested that radiation at a dose of higher than 25 kGy could stimulate the bacterial activity for metabolism of amino acid, carbohydrate and energy, etc, but damage the genes coding for cellular and genetic information processing. The major ecological risk is derived from ERY (high level) and TC (medium level) in the effluent. The ecological risk of ERY and TC could be declined to medium level and low level, respectively after radiation with 10 mM PMS/H2O2 addition at 25 kGy. However, the operating cost of EB/PMS processes was more than twice higher than that of EB/H2O2 processes. Based on the tech-economic evaluation, ionizing radiation combined with H2O2 was a promising technology for the advanced treatment of pharmaceutical wastewater.

Addition of Trichocladium canadense to an anaerobic membrane bioreactor: evaluation of the microbial composition and reactor performance

Membrane bioreactors are powerful systems for wastewater treatment and the removal of toxic compounds. However, membrane biofouling stands in the way of their widespread usage. In this study, the saprophytic fungus Trichocladium canadense was used as the bioaugmentor in an anaerobic membrane bioreactor (AnMBR) and its impact on membrane biofouling, biogas production, the microbial communities of the reactor and removal of the common antibiotics erythromycin (ERY), sulfamethoxazole (SMX) and tetracycline (TET) from synthetic wastewater was investigated. The results indicated that through bioaugmentation with 20% T. canadense, membrane biofouling was slowed by 25%, the chemical oxygen demand removal increased by 16% and a higher efficiency removal of ERY and SMX was achieved. The presence of T. canadense significantly increased the abundance and diversity of the biofilm archaeal community and the bacterial phylum Firmicutes, a known bio-foulant.

Treatment of pharmaceutical wastewater by ionizing radiation: Removal of antibiotics, antimicrobial resistance genes and antimicrobial activity

In present study, the treatment of real pharmaceutical wastewater from an erythromycin (ERY) production factory by gamma irradiation was investigated. Results showed that a variety of antimicrobial resistance genes (ARGs), involving MLSB, tet, bla, multidrug, sul, MGEs and van genes and plentiful 9 bacterial phyla were identified in the raw wastewater. In addition to ERY, sulfamethoxazole (SMX) and tetracycline (TC) were also identified with the concentration of 3 order of magnitude lower than ERY. Results showed that the abatement of ARGs and antibiotics was much higher than that of antimicrobial activity and COD. With the absorbed dose of 50 kGy, the removal percentage of ARGs, ERY, antimicrobial activity and COD was 96.5–99.8%, 90.0%, 47.8% and 10.3%, respectively. The culturable bacteria were abated fast and completely at 5.0 kGy during gamma irradiation. The genus Pseudomonas was predominant in raw wastewater (56.7%) and its relative abundance decreased after gamma irradiation, to 1.3% at 50 kGy. With addition of peroxymonosulfate (PMS, 50 mM), the antimicrobial activity disappeared completely and ERY removal reached as high as 99.2% at the lower absorbed dose of 25 kGy. Ionizing radiation-coupled technique is a potential option to treat pharmaceutical wastewater for reduction of antibiotics, ARGs and antimicrobial activity.

Bioaugmentation with immobilized endophytic Penicillium restrictum to improve quorum quenching activity for biofouling control in an aerobic hollow-fiber membrane bioreactor treating antibiotic-containing wastewater

The effects of bioaugmentation with immobilized Penicillium restrictum on the removal efficiency of sulfamethoxazole (SMX), erythromycin (ERY) and tetracycline (TC) antibiotics as well as membrane biofouling was studied using hollow-fiber membrane bioreactor (HF-MBR). Bioaugmentation with P. restrictum led to a significant change in the antibiotic removal efficiency and relative abundance of aerobic microbial community, most probably as a result of its quorum quenching activity. Furthermore, in addition to its role in the increase of SMX and ERY removal efficiencies and the decrease of their sorption on solid phase, bioaugmentation significantly reduced the transmembrane pressure which in turn reduced membrane clogging. The most abundant phyla in sludge and biofilm samples in the presence of P. restrictum were observed to be Proteobacteria, Bacteroidetes and Firmicutes. Differences in bacterial compositions and their specificity in biodegradation of antibiotics in different reactors showed that bacteria were specifically selected under the pressure of antibiotics and growing fungus.

Monitoring occurrence and removal of selected pharmaceuticals in two different wastewater treatment plants

The occurrence of pharmaceuticals in the environment is a concern due to its potential adverse effect on human health and ecology. In this research study, the occurrence of three selected pharmaceuticals—erythromycin (ERY), sulfamethoxazole (SMZ), trimethoprim (TMP), and an antimicrobial/antifungal agent triclosan (TRL) was monitored at two Southern California wastewater treatment plants (WWTPs). Between April and October of 2017, 77 composite samples were analyzed. Results from the study revealed the presence of all four pharmaceuticals in the influent at both WWTPs. Of the four pharmaceuticals, SMZ had the highest concentration (WWTP1, 1860 ng L−1, and WWTP2, 2146 ng L−1). In WWTP1, the concentrations of ERY, TRL, and TMP ranged from 33 to 278 ng L−1, 146 to 410 ng L−1, and 410 to 1021 ng L−1, respectively, while in WWTP2, their concentrations ranged from 16.7 to 209 ng L−1, 0 to 160 ng L−1, and 407 to 672 ng L−1, respectively. Even though both plants employed secondary biological treatment protocols, their removal efficiencies are remarkably different. WWTP1 is relatively more effective in the removal of ERY, TRL, and TMP with a removal efficiency of 46%, 63%, and 61%, respectively, while at WWTP2 only 4% TMP was removed, and no removal of ERY and TRL was observed. Both plants were unable to remove SMZ. Pharmaceuticals are bioactive compounds, and as such, even at low concentration levels, they may adversely affect the environment and will require additional treatment to ensure that treated wastewater meets the specific water quality criteria for reuse.

Efficacy of integrated ultraviolet ultrasonic technologies in the removal of erythromycin- and quinolone-resistant Escherichia coli from domestic wastewater through a laboratory-based experiment

Abstract Bacterial resistance to antibiotics has become a common occurrence especially in areas where antibiotic drugs are widely used. Moreover, the potential effect of antibiotic pollution and the presence of antibiotic-resistant genes (ARGs) on the composition of bacterial communities in the ecosystems continue to degrade the quality of most ecosystems. Despite the use of ultraviolet (UV) radiation and ultrasound (US) technologies in wastewater purification, little is known on their application in the elimination of fecal pathogenic microorganisms such as Escherichia coli. Moreover, their individual and combined potential in the elimination of erythromycin- and quinolone-resistant E. coli is a topic that still requires proper understanding. Therefore, this study was aimed at evaluating the individual and combined/integrative potential of UV radiation and ultrasonic technologies in the removal of erythromycin- and quinolone-resistant E. coli from domestic effluents using a laboratory experimental-based set-up. The results showed that UV radiation experiment was able to significantly eliminate erythromycin- and quinolone-resistant E. coli from the water to a value of 2 log units. Additionally, US technology was equally able to significantly reduce both the erythromycin- and quinolone-resistant E. coli to 2 log units. However, on combining the two technologies, there was further reduction to 1 log unit, hence, pointing to the need for adopting the integrative approach in water purification for increased wastewater purification efficiencies and improved ecosystem and human health.

Degradation performance and microbial community analysis of microbial electrolysis cells for erythromycin wastewater treatment

Antibiotics represent a major environmental health concern worldwide. In this study, a high concentration of erythromycin (ERY) was degraded by using single-chamber MECs with carbon cloth anodes. The electrochemical characteristics of MECs and the correlation with ERY were analysed. High-performance liquid chromatography analysis showed that the removal of ERY reached 99% when the influent concentration of ERY was 20 mg/L. In addition, ermG was the most common antibiotic resistance gene, whether in the reactor effluent (3.37×105 copies/μL DNA) or in the anode biofilm (0.21×105 copies/μL DNA), while ermA was not detected. The SEM images indicated that the anodic and cathodic biofilm were mature and well-constructed. High throughput sequencing of 16S rDNA gene amplicons indicated that Geobacter, as a known genus of exoelectrogenic bacteria, is very dominant in the reactor anode biofilm, with a relative abundance of 77.0%. Acetoanaerobium was widely present in the biocathode. These results indicate that MECs can be considered to be a useful and reliable technology for improving ERY biodegradation efficiency in wastewater, thus providing a meaningful economic output and efficient operation in future scale-ups.

Erythromycin degradation and ERY-resistant gene inactivation in erythromycin mycelial dreg by heat-activated persulfate oxidation

Erythromycin mycelial dreg (EMD) is a bio-fermentation residue of the pharmaceutical industry that may be used as a nutrient resource. However, the contaminants present in EMD need to be considered and controlled at an acceptable level prior to utilization. In this study, heat-activated persulfate (PS) oxidation of EMD was developed to degrade the residual erythromycin (ERY) and inactivate the ERY-resistant genes. The effects of temperature, initial PS concentration, and pH on the removal of ERY in EMD were studied. The results revealed that 99.0% ERY was degraded by 25 g PS/kg EMD under 80 °C within 120 min. The apparent rate constant (kapp) in the acidic condition was higher than that in the alkaline condition. The contribution of sulfate radical (SO4·-) and hydroxyl radical (HO) on ERY removal in EMD was found to be 36.8% and 29.4%, respectively. Six intermediate products (IPs) of ERY were clarified, and total organic carbon (TOC) was efficiently reduced by 99.4%. Finally, the detected ERY-resistant genes ere(B), erm(A), and erm(B) obviously presented a reduction during the heat-activated PS oxidation process.

Removal of antibiotics during the anaerobic digestion of pig manure

Antibiotics are frequently used in animals to treat sickness and prevent infection especially in industrial meat production. Some of the antibiotics cannot be completely metabolized and, as an unavoidable result, are excreted and thus end up in manure which is then spread in the environment. Currently increasing amounts of manure is used in biogas production before spreading the residuals on agricultural fields. In this study, the removal patterns of sulfonamides (sulfadiazine, sulfamethizole, sulfamethoxazole) and macrolides (clarithromycin, erythromycin), as well as trimethoprim, were investigated during the anaerobic digestion of pig manure. Batch kinetic tests were conducted both at thermophilic and psychrophilic condition for 40 days. Some of the antibiotics (clarithromycin, sulfadiazine, sulfamethizole) were persistent in all experiments. Thus, no biodegradation was found for sulfadiazine and sulfamethizole in this study. From the studied compounds, only erythromycin was clearly removed and probably degraded during anaerobic digestion with 99% and 20% removal under thermophilic and psychrophilic condition. The removal of erythromycin was fitted to a single first-order kinetic reaction function, giving reaction rate constant of 0.29day−1 and 0.005day−1, respectively.