Removal of trimethoprim and sulfamethoxazole in artificial composite soil treatment systems and diversity of microbial communities

• Novel ACST allowed biodegradation to effectively remove adsorbed SMX and TMP. • Ammonia and nitrite were efficiently removed in ACSTs and water quality was improved. Four artificial composite soil treatment systems (ACSTs) fed with reclaimed water containing trimethoprim (TMP) and sulfamethoxazole (SMX) were constructed to investigate SMX and TMP biodegradation efficiency, ammonia and nitrite removal conditions and the microbial community within ACST layers. Results showed SMX and TMP removal rates could reach 80% and 95%, respectively, and removal rates of ammonia and nitrite could reach 80% and 90%, respectively, in ACSTs. The MiSeq sequencing results showed that microbial community structures of the ACSTs were similar. The dominant microbial community in the adsorption and biodegradation layers of the ACSTs contained Proteobacteria, Chloroflexi, Acidobacteria, Firmicutes, Actinobacteria and Nitrospirae. Firmicutes and Proteobacteria were considerably dominant in the ACST biodegradation layers. The entire experimental results indicated that Nitrosomonadaceae_uncultured, Nitrospira and Bacillus were associated with nitrification processes, while Bacillus and Lactococcus were associated with SMX and TMP removal processes. The findings suggest that ACSTs are appropriate for engineering applications.     

Anaerobic biodegradation of trimethoprim with sulfate as an electron acceptor

Anaerobic biodegradation of trimethoprim (TMP) coupled with sulfate reduction. Demethylation of TMP is the first step in the acclimated microbial consortia. The potential degraders and fermenters were enriched in the acclimated consortia. Activated sludge and river sediment had similar core microbiomes. Trimethoprim (TMP) is an antibiotic frequently detected in various environments. Microorganisms are the main drivers of emerging antibiotic contaminant degradation in the environment. However, the feasibility and stability of the anaerobic biodegradation of TMP with sulfate as an electron acceptor remain poorly understood. Here, TMP-degrading microbial consortia were successfully enriched from municipal activated sludge (AS) and river sediment (RS) as the initial inoculums. The acclimated consortia were capable of transforming TMP through demethylation, and the hydroxyl-substituted demethylated product (4-desmethyl-TMP) was further degraded. The biodegradation of TMP followed a 3-parameter sigmoid kinetic model. The potential degraders (Acetobacterium, Desulfovibrio, Desulfobulbus, and unidentified Peptococcaceae) and fermenters (Lentimicrobium and Petrimonas) were significantly enriched in the acclimated consortia. The AS- and RS-acclimated TMP-degrading consortia had similar core microbiomes. The anaerobic biodegradation of TMP could be coupled with sulfate respiration, which gives new insights into the antibiotic fate in real environments and provides a new route for the bioremediation of antibiotic-contaminated environments.     

Mechanisms for simultaneous ozonation of sulfamethoxazole and natural organic matters in secondary effluent from sewage treatment plant

• SMX was mainly degraded by hydrolysis, isoxazole oxidation and double-bond addition. • Isoxazole oxidation and bond addition products were formed by direct ozonation. • Hydroxylated products were produced by indirect oxidation. • NOM mainly affected the degradation of SMX by consuming ^•OH rather than O₃. • Inhibitory effect of NOM on SMX removal was related to the components’ aromaticity. Sulfamethoxazole (SMX) is commonly detected in wastewater and cannot be completely decomposed during conventional treatment processes. Ozone (O₃) is often used in water treatment. This study explored the influence of natural organic matters (NOM) in secondary effluent of a sewage treatment plant on the ozonation pathways of SMX. The changes in NOM components during ozonation were also analyzed. SMX was primarily degraded by hydrolysis, isoxazole-ring opening, and double-bond addition, whereas hydroxylation was not the principal route given the low maximum abundances of the hydroxylated products, with m/z of 269 and 287. The hydroxylation process occurred mainly through indirect oxidation because the maximum abundances of the products reduced by about 70% after the radical quencher was added, whereas isoxazole-ring opening and double-bond addition processes mainly depended on direct oxidation, which was unaffected by the quencher. NOM mainly affected the degradation of micropollutants by consuming ^•OH rather than O₃ molecules, resulting in the 63%–85% decrease in indirect oxidation products. The NOM in the effluent were also degraded simultaneously during ozonation, and the components with larger aromaticity were more likely degraded through direct oxidation. The dependences of the three main components of NOM in the effluent on indirect oxidation followed the sequence: humic-like substances>fluvic-like substances>protein-like substances. This study reveals the ozonation mechanism of SMX in secondary effluent and provides a theoretical basis for the control of SMX and its degradation products in actual water treatment.     

Evaluating the impact of sulfamethoxazole on hydrogen production during dark anaerobic sludge fermentation

● SMX promotes hydrogen production from dark anaerobic sludge fermentation. ● SMX significantly enhances the hydrolysis and acidification processes. ● SMX suppresses the methanogenesis process in order to reduce hydrogen consumption. ● SMX enhances the relative abundance of hydrogen-VFAs producers. ● SMX brings possible environmental risks due to the enrichment of ARGs. The impact of antibiotics on the environmental protection and sludge treatment fields has been widely studied. The recovery of hydrogen from waste activated sludge (WAS) has become an issue of great interest. Nevertheless, few studies have focused on the impact of antibiotics present in WAS on hydrogen production during dark anaerobic fermentation. To explore the mechanisms, sulfamethoxazole (SMX) was chosen as a representative antibiotic to evaluate how SMX influenced hydrogen production during dark anaerobic fermentation of WAS. The results demonstrated SMX promoted hydrogen production. With increasing additions of SMX from 0 to 500 mg/kg TSS, the cumulative hydrogen production elevated from 8.07 ± 0.37 to 11.89 ± 0.19 mL/g VSS. A modified Gompertz model further verified that both the maximum potential of hydrogen production (P_m) and the maximum rate of hydrogen production (R_m) were promoted. SMX did not affected sludge solubilization, but promoted hydrolysis and acidification processes to produce more hydrogen. Moreover, the methanogenesis process was inhibited so that hydrogen consumption was reduced. Microbial community analysis further demonstrated that the introduction of SMX improved the abundance of hydrolysis bacteria and hydrogen-volatile fatty acids (VFAs) producers. SMX synergistically influenced hydrolysis, acidification and acetogenesis to facilitate the hydrogen production.     

Pollution and biodegradation of hexabromocyclododecanes: A review

• Bioremediation is the most cost-effective approach for degradation of HBCDs. • Bacteria or bacterial consortia are used in the cases of bio-augmentation. • Microbes combined with phytoremediation increase the remediation efficiency. Hexabromocyclododecanes (HBCDs) are the most common brominated flame-retardants after polybrominated diphenyl ethers. HBCDs can induce cancer by causing inappropriate antidiuretic hormone syndrome. Environmental contamination with HBCDs has been detected globally, with concentrations ranging from ng to mg. Methods to degrade HBCDs include physicochemical methods, bioremediation, and phytoremediation. The photodegradation of HBCDs using simulated sunlight or ultraviolet lamps, or chemical catalysts are inefficient and expensive, as is physicochemical degradation. Consequently, bioremediation is considered as the most cost-effective and clean approach. To date, five bacterial strains capable of degrading HBCDs have been isolated and identified: Pseudomonas sp. HB01, Bacillus sp. HBCD-sjtu, Achromobacter sp. HBCD-1, Achromobacter sp. HBCD-2, and Pseudomonas aeruginosa HS9. The molecular mechanisms of biodegradation of HBCDs are discussed in this review. New microbial resources should be explored to increase the resource library in order to identify more HBCD-degrading microbes and functional genes. Synthetic biology methods may be exploited to accelerate the biodegradation capability of existing bacteria, including modification of the degrading strains or functional enzymes, and artificial construction of the degradation microflora. The most potentially useful method is combining micro-degradation with physicochemical methods and phytoremediation. For example, exogenous microorganisms might be used to stimulate the adsorption capability of plants for HBCDs, or to utilize an interaction between exogenous microorganisms and rhizosphere microorganisms to form a new rhizosphere microbial community to enhance the biodegradation and absorption of HBCDs.     

The impact of the type and position of the halogen atom on the biodegradation of halosubstituted benzyl alcohols

The biodegradation of 2‐halosubstituted and 4‐halosubstituted benzyl alcohols was studied using two sources of biodegrative micro‐organisms: mixed culture from the ?TUDA waste water treatment plant, Dom?ale, and the white rot fungus Phanerochaete chrysosporium strain MZKI B‐223 (ATCC 24725). The results obtained by this study indicate the interrelationship between the types of micro‐organism used in the experiments and the type and position of the halogen element on the aromatic ring.     

含氨基酸的润滑油生物降解性及降解速率方程模拟

在HVI 350矿物润滑油中加入少量月桂酰基甘氨酸,对比研究了加入月桂酰基甘氨酸前后矿物润滑油在土壤中的生物降解特性,并采用指数速率模型对润滑油生物降解动力学进行了模拟.结果表明,月桂酰基甘氨酸可促进HVI 350矿物润滑油生物降解,试验条件下HVI 350矿物润滑油生物降解速率方程为S_t=50.4e~(-0.0155t),半衰期为44.72 d;含月桂酰基甘氨酸的HVI 350矿物润滑油生物降解速率方程为S_t=51.6e~(-0.0224t),半衰期为30.94d.     

Microbial biodegradation of plastics: Challenges,opportunities, and a critical perspective

● Health hazards of plastic waste on environment are discussed. ● Microbial species involved in biodegradation of plastics are being reviewed. ● Enzymatic biodegradation mechanism of plastics is outlined. ● Analytical techniques to evaluate the plastic biodegradation are presented. The abundance of synthetic polymers has increased due to their uncontrolled utilization and disposal in the environment. The recalcitrant nature of plastics leads to accumulation and saturation in the environment, which is a matter of great concern. An exponential rise has been reported in plastic pollution during the corona pandemic because of PPE kits, gloves, and face masks made up of single-use plastics. The physicochemical methods have been employed to degrade synthetic polymers, but these methods have limited efficiency and cause the release of hazardous metabolites or by-products in the environment. Microbial species, isolated from landfills and dumpsites, have utilized plastics as the sole source of carbon, energy, and biomass production. The involvement of microbial strains in plastic degradation is evident as a substantial amount of mineralization has been observed. However, the complete removal of plastic could not be achieved, but it is still effective compared to the pre-existing traditional methods. Therefore, microbial species and the enzymes involved in plastic waste degradation could be utilized as eco-friendly alternatives. Thus, microbial biodegradation approaches have a profound scope to cope with the plastic waste problem in a cost-effective and environmental-friendly manner. Further, microbial degradation can be optimized and combined with physicochemical methods to achieve substantial results. This review summarizes the different microbial species, their genes, biochemical pathways, and enzymes involved in plastic biodegradation.     

The impact of different voltage application modes on biodegradation of chloramphenicol and shift of microbial community structure

● Presented coupled system enhanced biodegradation of antibiotic chloramphenicol. ● HRT and electrical stimulation modes were key influencing factors. ● Electrical stimulation had little effect on the chloramphenicol metabolic pathway. ● Microbial community structure varied with the voltage application mode. Exoelectrogenic biofilms have received considerable attention for their ability to enhance electron transfer between contaminants and electrodes in bioelectrochemical systems. In this study, we constructed anaerobic-aerobic-coupled upflow bioelectrochemical reactors (AO-UBERs) with different voltage application modes, voltages and hydraulic retention times (HRTs). In addition, we evaluated their capacity to remove chloramphenicol (CAP). AO-UBER can effectively mineralize CAP and its metabolites through electrical stimulation when an appropriate voltage is applied. The CAP removal efficiencies were ~81.1%±6.1% (intermittent voltage application mode) and 75.2%±4.6% (continuous voltage application mode) under 0.5 V supply voltage, which were ~21.5% and 15.6% greater than those in the control system without voltage applied, respectively. The removal efficiency is mainly attributed to the anaerobic chamber. High-throughput sequencing combined with catabolic pathway analysis indicated that electrical stimulation selectively enriched Megasphaera, Janthinobacterium, Pseudomonas, Emticicia, Zoogloea, Cloacibacterium and Cetobacterium, which are capable of denitrification, dechlorination and benzene ring cleavage, respectively. This study shows that under the intermittent voltage application mode, AO-UBERs are highly promising for treating antibiotic-contaminated wastewater.     

Removal of textile dyes from water by the electro-Fenton process

An environmentally friendly electrochemical treatment, electro-Fenton process, was applied to the depollution of a synthetic dismissal composed of three dyes, yellow drimaren, congo red and methylene blue, frequently used in textile and dyehouses. Here, we show that those dyes and their mixture are quickly degraded under current controlled electrolysis conditions, leading to an almost complete mineralization. The results show the efficiency of electro-Fenton process to quickly degrade aqueous effluents polluted by synthetic organic dyes.     

Removal of fluoride from water using titanium-based adsorbents

Three adsorbents including TiO₂, Ti-Ce, and Ti-La hybrid oxides were prepared to remove fluoride from aqueous solution. The Ti-Ce and Ti-La hybrid adsorbents obtained by the hydrolysis-precipitation method had much higher sorption capacity for fluoride than the TiO₂ adsorbent prepared through hydrolysis. Rare earth (Ce and La) oxides and TiO₂ exhibited a synergistic effect in the hybrid adsorbents for fluoride sorption. The sorption equilibrium of fluoride on the three adsorbents was achieved within 4 h, and the pseudo-second-order model described the sorption kinetics well. The sorption isotherms fitted the Langmuir model well, and the adsorption capacities of fluoride on the Ti-Ce and Ti-La adsorbents were about 9.6 and 15.1 mg·g^-1, respectively, at the equilibrium fluoride concentration of 1.0 mg·L^-1, much higher than the 1.7 mg·g^-1 on the TiO₂. The sorption capacities of fluoride on the three adsorbents decreased significantly when the solution pH increased from 3 to 9.5. The electrostatic interaction played an important role in fluoride removal by the three adsorbents, and Fourier transform infrared (FTIR) analysis indicated that the hydroxyl groups on the adsorbent surface were involved in fluoride adsorption.     

Genotoxic potential of organic extracts from municipal reclaimed water in Tianjin,China

Despite increasing pressure to make more efficient use of water resources, the widespread use of reclaimed water still remains a contentious issue, primarily because of risks to human health arising from water pollution by organic compounds. Therefore, safety evaluation of reclaimed water is an urgent need. The aim of this study was to determine the genotoxic potential of reclaimed water during low and high water periods. Reverse phase C-18 solid-phase extraction (RP-C18SPE) was used for the extraction of organic compounds from water samples. The tests, namely, Ames, micronucleus and chromosome aberrations were used to determine the damage caused by water samples on genetic material. Ames tests showed that both influent and effluent reclaimed water, except influent after metabolism by S9 in high water period, induced mutation of TA98 and TA100 strains of Salmonella typhimurium in a concentration-response manner. There were no significant differences in micronucleus and chromosome aberration tests. Even after treatment, reclaimed water in Tianjin still showed mutational effects and new strategies for reduction of genotoxins need to be considered.     

Removal of the herbicide amitrole from water by anodic oxidation and electro-Fenton

Here we demonstrate that an aqueous solution of the herbicide amitrole can be completely depolluted at pH 3.0 by anodic oxidation and electro-Fenton process. Anodic oxidation gives faster degradation with a boron-doped diamond anode than with a Pt anode. Electro-Fenton with a Pt anode and 1 mmol l ^–1 Fe²⁺ as catalyst yields the quickest depollution. Amitrole decay always follows a pseudo first-order reaction. NO₃^– and NH₄⁺ are accumulated in the medium during mineralization, although volatile N-products are also formed. These environmentally friendly electrochemical treatments could be applied to the remediation of wastewaters containing amitrole.     

Research progress on distribution,sources, identification,toxicity, and biodegradation of microplastics in the ocean,freshwater, and soil environment

• Microplastics are widely found in both aquatic and terrestrial environments. • Cleaning products and discarded plastic waste are primary sources of microplastics. • Microplastics have apparent toxic effects on the growth of fish and soil plants. • Multiple strains of biodegradable microplastics have been isolated. Microplastics (MPs) are distributed in the oceans, freshwater, and soil environment and have become major pollutants. MPs are generally referred to as plastic particles less than 5 mm in diameter. They consist of primary microplastics synthesized in microscopic size manufactured production and secondary microplastics generated by physical and environmental degradation. Plastic particles are long-lived pollutants that are highly resistant to environmental degradation. In this review, the distribution and possible sources of MPs in aquatic and terrestrial environments are described. Moreover, the adverse effects of MPs on natural creatures due to ingestion have been discussed. We also have summarized identification methods based on MPs particle size and chemical bond. To control the pollution of MPs, the biodegradation of MPs under the action of different microbes has also been reviewed in this work. This review will contribute to a better understanding of MPs pollution in the environment, as well as their identification, toxicity, and biodegradation in the ocean, freshwater, and soil, and the assessment and control of microplastics exposure.     

一株贫营养异养硝化-好氧反硝化菌的筛选及脱氮特性

为了探究并优化菌剂应用于微污染水源水体修复的机制和条件,主要针对水库沉积物内筛选出的贫营养好氧反硝化菌进行了菌种鉴定及脱氮特性研究,考察菌株在不同环境条件下的脱氮效果,明确了该菌株的最适宜生长条件,并基于水库水体中贫营养条件对菌株进行水源水库原水的驯化培养试验研究,以期实现该菌株对微污染水源水库原水中氮源污染物的脱除,为原位投菌技术实际工程应用提供理论依据。从微污染水源水库沉积物中驯化筛分出一株高效异养硝化-好氧反硝化菌A14,通过扫描电镜观察、生理生化特征、16S rRNA基因测序和Biolog GenⅢ鉴定,确定该菌株为革兰氏阴性短杆菌,鉴定为皮特不动杆菌（Acinetobacter pittii）。在好氧条件下,菌株细胞内表达反硝化功能基因napA,以NO3-为唯一氮源进行反硝化作用时,36 h时NO3-去除率为78.89%。以NH4+为唯一氮源时,48 h NH4+去除率为95.25%,TN去除率达80.42%,TOC去除率达98.30%,表明该菌株具有异养硝化-好氧反硝化特性。在改变环境条件过程中,该菌株在以乙酸钠为碳源,温度为30℃,C/N为12,pH为7,接种量为10%时,NO3-去除率最高为86.62%,并且在10℃下脱氮率达到40.18%。在水源水库原水脱氮实验中,接种处理TN去除率为50.95%,NO3-去除率为80.25%。结果表明,菌株A14在微污染水源水体菌剂脱氮修复中具有良好的应用潜力。     

Removal of organophosphorus pesticides from water by electrogenerated Fenton's reagent

Aqueous solutions of organophosphorus pesticides were completely mineralized via in-situ generated hydroxyl radicals (HO^·) by the Electro-Fenton process. Formation of Fenton's reagent (H₂O₂, Fe²⁺) was carried out by simultaneous reduction of O₂ and Fe³⁺ on carbon cathode in acidic medium. The electrochemistry combined with Fenton's reagent provides an excellent way to continuously produce the hydroxyl radical, a powerful oxidant. We demonstrate the efficiency of the Electro-Fenton process to degrade three organophosphorus insecticides: malathion, parathion ethyl and tetra-ethyl-pyrophosphate (TEPP). Degradation kinetics and removals of chemical oxygen demand (COD) have been investigated. Here we show that the mineralization efficiency was over 80% for three organophosphorus pesticides.     

活性艳红X-3B的厌氧生物降解与机理

以活性艳红X-3B(RBR)为研究对象,分3个不同浓度组研究其在厌氧颗粒污泥作用下的降解性能,并采用生物降解动力学方程拟合其降解过程,同时利用GC-MS分析RBR的生物降解途径.试验结果表明,RBR在厌氧颗粒污泥中降解性能很好,去除率可达93.67%,且其降解过程符合二级反应动力学,其半衰期约为3.561 h.从GC-MS和UV-可见光谱的分析得出,RBR在厌氧颗粒污泥的作用下偶氮键断裂,且生成的芳香胺类化合物进一步降解为小分子的烃类、酚类、醇类和脂类化合物.     

再生水用于景观水体的氮磷水质标准确定

污水再生利用是解决水资源短缺问题的重要措施,其中再生水回用于景观水体是主要途径之一.而防止水华爆发则是再生水景观利用的首要任务,控制再生水中的氮磷是防止水华爆发的根本措施.目前已有的景观水体水质标准中,氮磷浓度限值要求不统一,缺乏科学依据.因此再生水处理过程中氮磷控制标准执行易出现矛盾,不利于保障再生水景观利用的水质安全.再生水景观利用的氮磷控制标准,应在藻类最大生长潜力研究的基础上,通过藻类生长的Logistic模型和Monod模型、景观水体氮磷浓度模型按拟合,并结合水体自净能力和水质保障措施等综合因素加以确定.以栅藻(Scenedesmus sp)为例,通过Logistic模型和Monod模型拟合景观水体水华控制氮磷浓度限值的确定方法.     

Fate and risk assessment of emerging contaminants in reclaimed water production processes

• PPCPs had the highest removal efficiency in A²O combined with MBR process (86.8%). • ARGs and OPFRs were challenging to remove (6.50% and 31.0%, respectively). • Octocrylene and tris(2-ethylhexyl) phosphate posed high risks to aquatic organisms. • Meta-analysis was used to compare the ECs removal in wastewater treatment. • Membrane treatment technology is the most promising treatment for ECs removal. Reclaimed water has been widely applied in irrigation and industrial production. Revealing the behavior of emerging contaminants in the production process of reclaimed water is the first prerequisite for developing relevant water quality standards. This study investigated 43 emerging contaminants, including 22 pharmaceuticals and personal care products (PPCPs), 11 organophosphorus flame retardants (OPFRs), and 10 antibiotic resistance genes (ARGs) in 3 reclaimed wastewater treatment plants (RWTPs) in Beijing. The composition profiles and removal efficiencies of these contaminants in RWTPs were determined. The results indicated that the distribution characteristics of the different types of contaminants in the three RWTPs were similar. Caffeine, sul2 and tris(1-chloro-2-propyl) phosphate were the dominant substances in the wastewater, and their highest concentrations were 27104 ng/L, 1.4 × 10⁷ copies/mL and 262 ng/L, respectively. Ofloxacin and sul2 were observed to be the dominant substances in the sludge, and their highest concentrations were 5419 ng/g and 3.7 × 10⁸ copies/g, respectively. Anaerobic/anoxic/oxic system combined with the membrane bioreactor process achieved a relatively high aqueous removal of PPCPs (87%). ARGs and OPFRs were challenging to remove, with average removal rates of 6.5% and 31%, respectively. Quantitative meta-analysis indicated that tertiary treatment processes performed better in emerging contaminant removal than secondary processes. Diethyltoluamide exhibited the highest mass load discharge, with 33.5 mg/d per 1000 inhabitants. Octocrylene and tris(2-ethylhexyl) phosphate posed high risks (risk quotient>1.0) to aquatic organisms. This study provides essential evidence to screen high priority pollutants and develop corresponding standard in RWTPs.     

Removal of congo red dye from water using carbon slurry waste

A cheaper adsorbent has been prepared from carbon slurry waste obtained from National Fertilizer Limited (NFL), Panipat and investigated for the removal of congo red, an anionic dye. Its adsorption on prepared carbonaceous adsorbent was studied as a function of contact time, concentration and temperature. The results have shown that carbonaceous adsorbent adsorbs dye to a sufficient extent (272 mg g^-1). A comparative study of adsorption results with those obtained on activated charcoal shows that the carbonaceous adsorbent is ~95% efficient as compared to activated charcoal. Thus, it can be fruitfully used for the removal of dyes from wastewaters.This work has been presented at the National Symposium on Biochemical Sciences: Health and Environmental Aspects (BSHEA—2003), Agra, India (2003).