Ferromanganese oxide-functionalized TiO2 for rapid catalytic ozonation of PPCPs through a coordinated oxidation process with adjusted composition and strengthened generation of reactive oxygen species.

Ferromanganese oxide (MFOx) was first utilized to functionalize TiO2 and an MFOx@TiO2 catalyst was developed for catalytic ozonation for rapid attack of pharmaceutical and personal care products (PPCPs) with adjusted reactive oxygen species (ROSs) composition and strengthened ROSs generation. Unlike Al2O3, which strongly relied on adsorption and was significantly influenced by MFOx loading, synergistic catalytical effects of MFOx and TiO2 were observed, and optimal MFOx doping of 2 wt% and MFOx@TiO2 dosage of 500 ppm were obtained for catalyzing ozonation. In ibuprofen (IBP) degradation, MFOx@TiO2-catalyzed ozonation (MFOx@TiO2/O3) obtained 2.0-, 4.7- and 6.9-folds the kobs of TiO2/O3, MFOx/O3 and bare ozonation (B/O3). Stronger O3 decomposition was observed by MFOx@TiO2 over bare TiO2 with the participation of redox pairs Fe(II)/Fe(III) and Mn(II)/Mn(III)/Mn(IV) and increased surface oxygen vacancies (SOVs) from 9.8 % to 33.7 % was detected. The results revealed that Fe(II), Mn(II) and Mn(III) with low valance accelerated Ti(III) generation from Ti(VI), obtaining an unprecedented high Ti(III) composition occupying 35.3 % of the total Ti atoms. Ti(III) catalyzed the direct reduction of SOVs-O2 to •O2-, and it accelerated the formation of Ti(VI)-OH and Ti(VI)-O which catalyzed O3 decomposition into •O2-. •O2- was found to primarily initiate IBP degradation with nucleophilic addition and dominated over 66 % IBP removal. The enhanced •O2- generation further strengthened •OH and 1O2 production. MFOx@TiO2/O3 obtained 17 %, 21 % and 30 % higher TOC removal over TiO2/O3, MFOx/O3 and B/O3, respectively. Acute toxicity tests confirmed the effective toxicity control of organics by MFOx@TiO2/O3 process (inhibition rate: 10.9 %). Degradation test of atenolol and sulfamethoxazole confirmed the catalytic effects of MFOx@TiO2. MFOx@TiO2 performed strong resistance to water matrix in application test and showed good stability and reusability. The study proposed an effective catalyst for strengthening the ozonation process on PPCPs degradation and provided an in-depth understanding of the mechanisms and characteristics of the MFOx@TiO2 catalyst and MFOx@TiO2/O3 process.

Pollutants removal and connections among sludge properties, metabolism potential and microbial characteristics in aerobic granular sequencing batch reactor for petrochemical wastewater treatment.

Petrochemical wastewater contains inhibitory compounds such as aromatics that are toxic to microorganisms during biological treatment. The compact and layered structure and the high amount of extracellular polymeric substances (EPS) in aerobic granular sludge (AGS) can contribute to protecting microorganisms from the harsh environment. This study evaluated the changes in the granule properties, pollutants removal, microbial metabolic potential and molecular microbial characteristics of the AGS process for petrochemical wastewater treatment. Granules treating petrochemical wastewater had a higher SVI30/SVI5 value (0.94) than that treating synthetic wastewater. An increase in bioactivity and EPS secretion with higher bio-polymer composition, specifically the functional groups such as hydroxyl, alkoxy and amino in protein, was observed, which promoted biomass aggregation. The granules also had more than 2-fold higher specific oxygen utilization rate. The AGS-SBR process obtained an average COD removal of 93% during petrochemical wastewater treatment and an effluent bCOD of below 1 mg L-1. No obvious inhibition of nitrification and denitrification activity was observed in the processes attributed to the layered structure of AGS. The average effluent NH4+-N of 5.0 mg L-1 was obtained and TN removal efficiencies of over 80.0% was achieved. Molecular microbial analysis showed that abundant functional genera Stenotrophomonas and Pseudoxanthomonas contributed to the degradation of aromatics and other petroleum organic pollutants. They were enriched with the variation of group behavior while metabolisms of amino acids and carboxylic acids by the relevant functional genera (e.g., Cytophagia) were significantly inhibited. The enrichment of Flavobacterium and Thermomonas promoted nitrification and denitrification, respectively. This research revealed the rapid start-up, enhanced granule structural strength, high inhibition resistance and considerable performance of AGS-SBR for petrochemical wastewater treatment.

Comparative review on microbial electrochemical technologies for resource recovery from wastewater towards circular economy and carbon neutrality.

Newly arising concepts such as the circular economy and carbon neutrality motivate resource recovery from wastewater. This paper reviews and discusses state-of-the-art microbial electrochemical technologies (METs), specifically microbial fuel cells (MFCs), microbial electrolysis cells (MECs) and microbial recycling cells (MRCs), which enable energy generation and nutrient recovery from wastewater. Mechanisms, key factors, applications, and limitations are compared and discussed. METs are effective in energy conversion, demonstrating advantages, drawbacks and future potential as specific scenarios. MECs and MRCs exhibited greater potential for simultaneous nutrient recovery, and MRCs offer the best scaling-up potential and efficient mineral recovery. Research on METs should be more concerned with lifespan of materials, secondary pollutants reduction and scaled-up benchmark systems. More up-scaled application cases are expected for cost structures comparison and life cycle assessment of METs. This review could direct the follow-up research, development and successful implementation of METs for resource recovery from wastewater.

Release of microplastics from breastmilk storage bags and assessment of intake by infants: A preliminary study.

The occurrence of microplastic contaminants in food intended for human consumption has been widely explored. Yet, investigations on plastic and other particle debris in baby food packaging remain scarce to date. Our study shows the release of abundant micro-sized and submicron-sized particles, floccules (<300 µm), and fragments (1-50 µm) during the simulated use of commercially available single-use breastmilk storage bags. Six best-selling products of breastmilk storage bags were selected in our study. Most of the particles released from breastmilk storage bags that were identified as plastics were found to be polyethylene (PE), polyethylene terephthalate (PET), and nylon-6 using micro-Raman spectroscopy. The weight of the particles released from three randomly selected bags of the same product type was determined to be in the range of 0.22 and 0.47 mg. Submicron-sized particles (<0.8 µm) with irregular spherical or oval shapes were present. Microplastics and other particles ingested by infants from the use of breastmilk storage bags were estimated to be 0.61-0.89 mg/day based on the average daily breastmilk intake by infants. This study provides new insights into the exposure to microplastics and other particle debris in commonly used infant products.

It is time to acknowledge coronavirus transmission via frozen and chilled foods: Undeniable evidence from China and lessons for the world.

Since the broke out of the novel coronavirus disease at the end of 2019, nearly 650 million people have been infected around the globe, and >6.6 million have died from this disease. The first wave of infections in mainland China had been effectively controlled within a short period, with no domestic cases of infection for 56 consecutive days from April 16, 2020. Nonetheless, the re-emergence of several outbreaks in multiple Chinese cities posed a new challenge for public health authorities after new cases of infections were found in Xinfadi Market in Beijing on June 11, 2020. In the following series of re-emergent outbreaks, findings from epidemiological investigations suggested that more than twenty re-emergent outbreaks were caused by fomite transmission, predominantly via imported frozen and chilled foods contaminated by the SARS-CoV-2 virus. Seven of the eleven incidents involving frozen and chilled foods were identified by screening individuals with occupational exposure to imported cold-chain foods and associated individuals. Evidence showed that low temperatures and poor ventilation typically maintained through cold-chain logistics create amenable environments for the survival of SARS-CoV-2, making transnational cold chain logistics a congenial vehicle to spread the virus through global transport of consumer goods. To address this gap, here we present a scrutiny of the findings from epidemiological investigations in recent re-emergent outbreaks in China caused by fomite transmission via imported foods and goods. A national regime of traceable cold-chain foods and reinforced customs inspection protocols were established by public health authorities in mainland China as emergency responses to recurring outbreaks from fomite transmission via imported goods. We urge that more attention needs to be given to this specific route of pathogenic transmission to ensure biosecurity and to increase the preparedness for epidemic or pandemic scenarios by the global food industry and logistics carriers.

Non-Covalent Bond-Regulated Solar Evaporation Modulator: Facilitative Hydration Domains Originated via a Homogeneous Polymeric Network.

The solar-driven evaporation technology provides a green alternative for solving water scarcity. However, it remains challenging to improve the steam conversion efficiency due to the difficulties in simultaneously coordinating light absorbance, water regulation, and thermal management for broadband solar evaporators. Here, an unconventional solar evaporative modulator material─ultra-interfacial adherent dimethyl sulfoxide polyvinyl alcohol (DMSO-PVA) hydrogel (DPH) was presented. The material is based on the regulation of the PVA-PVA intra- and PVA-water interchain hydrogen bonds by DMSO, which established an adaptive high-cross-linking and homogeneous network. The consequent ultra-thin hydrogel exploited an insulating polymer backbone and intracavity hydration domain to simultaneously improve the light absorption and thermal localization and activate the water molecule. As a proof-of-concept, under 1 sun illumination (1 kW m-2), a DPH-based graphene fiber membrane [ultra-thin hydrogel membrane (UHM)] achieved 97% light absorption, 2.33 kg m-2 h-1 water evaporation, and high salt-resistant evaporation (1.48 kg m-2 h-1 under 25 wt % brine). Compared to the pure graphene membrane, UHM increased the vaporization by 64%, decreased the heat diffusion by over 14-folds, and reduced the environmental heat loss by 2.6-folds. DPH possesses scalability and versatility in bridging nanoscale photothermal materials and solar evaporator geometric architecture and will facilitate the possibility of advanced solar thermal applications.

Impact factors and novel strategies for improving biohydrogen production in microbial electrolysis cells.

Microbial electrolysis cell (MEC) system is an environmentally friendly method for clean biohydrogen production from a wide range of biowastes owing to low greenhouse gas emissions. This approach has relatively higher yields and lower energy costs for biohydrogen production compared to conventional biological technologies and direct water electrolysis, respectively. However, biohydrogen production efficiency and operating costs of MEC still need further optimization to realize its large-scale application.This paper provides a unique review of impact factors influencing biohydrogen production in MECs, such as microorganisms and electrodes. Novel strategies, including inhibition of methanogens, development of novel cathode catalyst, advanced reactor design and integrated systems, to enhance low-cost biohydrogen production, are discussed based on recent publications in terms of their opportunities, bottlenecks and future directions. In addition, the current challenges, and effective future perspectives towards the practical application of MECs are described in this review.

Efficient bio-refractory industrial wastewater treatment with mitigated membrane fouling in a membrane bioreactor strengthened by the micro-scale ZVI@GAC galvanic-cells-initiated radical generation and coagulation processes.

Micro-scale ZVI@GAC-based iron-carbon galvanic-cells (ZVI@GACs) were prepared with the Ca-Si-H/Ca-H formation process and first applied to initiate radical generation and coagulation processes in MBR for treating bio-refractory industrial wastewater (IWW). Batch tests revealed the H2O2 production (0.19-0.28 mg/L) and •OH generation (p-CBA decay, k1 = 0.040 min-1) in ZVI@GACs-dosed system (packing volume of 5%) under aeration. Adoption of ZVI@GACs into aerobic activated sludge process (ZVI@GACs/AS) enhanced TOC degradation (k2) and phenolic compounds (PHENs) destruction (k3). ZVI@GACs/AS at ZVI@GACs packing volume of 5%, 10% and 20% improved k2 from 0.11 h-1 (bare AS) to 0.17, 0.21 and 23 h-1 and k3 from 0.24 h-1 to 0.36, 0.49 and 0.57 h-1, respectively. The oxygen uptake rate (OUR) and 15-min acute bio-toxicity demonstrated that the bio-toxicity of IWW was reduced and the activity of biomass was enhanced in the ZVI@GACs/AS system. In MBR, ZVI@GACs at packing volume of 10% enhanced COD and PHENs removal by 14% and 22%, respectively. Membrane fouling cycle was prolonged by 71%. The accumulations of EPS-proteins, EPS-polysaccharides, SMP-proteins and SMP-polysaccharides were reduced by 6%, 67%, 27% and 60%, respectively. Fourier transform infrared spectroscopy (FTIR) confirmed the oxidation of SMP-polysaccharides in ZVI@GACs-MBR. The iron ions released from ZVI@GACs showed inhibition on the secretion of SMP-/EPS-proteins. Floc particle size distribution (PSD) and X-ray diffraction (XRD) spectrum confirmed that the coagulation effects of Fe(OH)3 and FeOOH triggered by Fe3+ increased the sludge floc size and contributed to membrane fouling mitigation. Genus Enterococcus was enriched in MBR with the destruction of PHENs by the ZVI@GACs-initiated radical generation process. The findings of this study confirmed successful development and adoption of ZVI@GACs into MBR for bio-refractory IWW treatment. It also provided an in-depth understanding on the mechanisms of ZVI@GACs-MBR system.

Cultivation of aerobic granular sludge coupled with built-in biochemical cycle galvanic-cells driven by dual selective pressure and its denitrification characteristics.

Dual selective pressure was applied as the driving condition to cultivate an enhanced aerobic granular sludge (AGS) with Fe(0)-based biochemical cycle galvanic-cells (BCGC) as the core. The BCGC-AGS coupled micro-electrolysis with synergistic autotrophic-heterotrophic denitrification to enhance nitrogen removal. COD and total nitrogen removal of 91.8% and 95.9% were achieved, respectively. The formation of circulation channel between Fe3+ and Fe2+ provided a solid foundation for the biochemical cycle of galvanic-cells with low consumption. The existence of micro-electrolysis selective pressure in BCGC-AGS was also confirmed. Facultative aerobic bacteria Methylocystis and Azospirillum were the most abundant genera. Facultative iron redox bacteria and autotrophic denitrifying bacteria Geobacter, Thiobacillus, Aquabacterium, Thauera and Azospirillum showed high abundance, affirming the success culture of EAGS system. Load shock test verified BCGC-AGS possessed excellent load shock resistance. Obtaining the advantages of fast-cultivation, high-efficiency and low galvanic-cells consumption, BCGC-AGS showed significant potential for practical application.

Performance and microbial community dynamics relationship within a step-feed anoxic/oxic/anoxic/oxic process (SF-A/O/A/O) for coking wastewater treatment.

A step-feed anoxic/oxic/anoxic/oxic (SF-A/O/A/O) was developed and successfully applied to full-scale coking wastewater treatment. The performance and microbial community were evaluated and systematically compared with the anoxic/oxic/oxic (A/O/O) process. SF-A/OA/O process exhibited efficient removal of COD, NH4+-N, TN, phenols, and cyanide with corresponding average effluent concentrations of 317.9, 1.8, 46.2, 1.1, and 0.2 mg·L-1, respectively. In particular, the TN removal efficiency of A/O/O process was only 7.8%, with an effluent concentration of 300.6 mg·L-1. Furthermore, polycyclic aromatic hydrocarbons with high molecular weight were the dominant compounds in raw coking wastewater, which were degraded to a greater extent in SF-A/OA/O. The abundance in Thiobacillus, SM1A02, and Thauera could be the main reason why SF-A/O/A/O was superior to A/O/O in treating TN. The microbial community structure of SF-A/O/A/O was similar among stages in system (P ≥ 0.05, Welch's t-test) and was less affected by environmental factors, which may have been one of the important factors in the system's strong stability.

Highly efficient removal of phosphorus from agricultural runoff by a new akadama clay barrier-vegetated drainage ditch system (VDD) and its mechanism.

A vegetated drainage ditch (VDD) system is an effective management practice for removing excess phosphorus (P) from agricultural runoff. However, the maximization of P removing efficiency by VDD remains a challenge. In this study, new VDDs with akadama clay barriers (particle size of clay: 1-6 mm; height of barrier: 5-15 cm and length of barrier: 10-90 cm) were designed in lab scale, and the mechanism of phosphate removal by akadama clay was investigated. It was found that a new VDD with akadama clay barriers (particle size:1 mm; height:10 cm and length: 90 cm) exhibited the highest removal efficiency of total P (TP) (97.1%), particulate P(PP) (96.9%), and dissolved P (DP) (97.4%), respectively. The retained P was mainly adsorbed in akadama clay barrier sections, and a low concentration of P was observed in soil sections in the new VDD. The maximum adsorption capacity of phosphate to akadama clay was 5.06 mg/g at 298 K, and XPS analysis indicated that phosphate was adsorbed by the inner-sphere complexation formation with the metal elements (Al, Fe). This study indicates that the new VDD with akadama clay barriers is a promising technique to efficiently remove P from agricultural runoff and significantly minimize the risk of P release into streams through runoff.

Microbial community dynamic shifts associated with sulfamethoxazole degradation in microbial fuel cells.

Though sulfamethoxazole (SMX) degradation at the low or medium concentration (SMX< 30 mg/L) has been reported in the microbial fuel cell (MFC), further exploration is still urgently required to investigate how the high concentration of SMX affect the anode biofilm formation. In this study, the degradation mechanism of SMX and the response of microbial community to SMX at different initial concentrations (0, 0.5, 5 and 50 mg/L) were investigated in MFCs. The highest SMX removal efficiency of 98.4% was obtained in MFC (5 mg/L). SMX at optimal concentration (5 mg/L) could serve as substrate accelerating the extracellular electron transfer. However, high concentration of SMX (50 mg/L) conferred significant inhibition on the electron transfer with SMX removal decline to 84.4%. The 16S rRNA high-throughput sequencing revealed the significant shift of the anode biofilms communities with different initial SMX concentrations were observed in MFCs. Thauera and Geobacter were the predominant genus, with relative abundance of 31.9% in MFC (50 mg/L SMX) and 52.7% in MFC (5 mg/L SMX). Methylophilus exhibited a huge increase with the highest percentage of 16.4% in MFC (50 mg/L). Hence, the functional bacteria of Thauera, Geobacter and Methylophilus endowed significant tolerance to the selection pressure from high concentration of SMX in MFCs. Meanwhile, some bacteria including Ornatilinea, Dechloromonas and Longilinea exhibited a decrease or even disappeared in MFCs. Therefore, initial concentrations of SMX played a fundamental role in modifying the relative abundance of predominant populations. This finding would promote theories support for understanding the evolution of anode biofilm formation related to the different initial concentrations of SMX in MFCs.

FeOx@GAC catalyzed microbubble ozonation coupled with biological process for industrial phenolic wastewater treatment: Catalytic performance, biological process screening and microbial characteristics.

Phenolic compounds are common ccontaminants in industrial effluents. In this study, a combined catalytic microbubble ozonation and biological process was developed and applied for efficient industrial phenolic wastewater (PWW) treatment. Catalytic activity of an iron-oxides (FeOx) doped granular activated carbon (GAC) catalyst (FeOx@GAC) in microbubble ozonation for PWW treatment was investigated. The results demonstrated that the FeOx@GAC catalyzed microbubble ozonation (O3/FeOx@GAC) obtained significantly higher reaction rate constant (k1 = 0.023 min-1) in TOC removal compared to the bare GAC catalyzed microbubble ozonation (O3/GAC, k1 = 0.013 min-1) and ordinary microbubble ozonation (k1 = 0.008 min-1). Destruction rate constant of phenolic compounds (k2) was improved from 0.014 min-1 (ordinary microbubble ozonation) to 0.025 min-1 (O3/FeOx@GAC). The 60-min pretreatment of PWW by O3/FeOx@GAC process enhanced BOD5/COD ratio from 0.31 to 0.76 and reduced the acute bio-toxicity by 79.2%. Screening and characterization of biological post-treatment processes were conducted among activated sludge process (ASP), up-flow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR). UASB and ASP showed limited phenolic compounds removal of 35.4% and 57.0% with lower bio-toxicity resistance than MBR (94.9% phenolic compounds removal). The combined process O3/FeOx@GAC-MBR was thus developed and achieved high COD removal (98.0%) and phenolic compounds degradation (99.4%). PWW pretreatment by O3/FeOx@GAC process decreased membrane fouling rate of MBR by 88.2% by reducing proteins/polysaccharides accumulation in both extracellular polymeric substances and soluble microbial products. 16S rRNA high-throughput sequencing revealed the predominance of phylum Proteobacteria, class Alphaproteobacteria and genera Mycobacterium, Gordonia, Pedomicrobium & Defluviimonas in biological PWW treatment bio-systems. Pearson correlation coefficient and ANOVA analysis verified that Mycobacterium possessed high bio-toxicity resistance and was the main contributor to the biodegradation of phenolic compounds.

Application of iron [Fe(0)]-rich substrate as a novel capping material for efficient simultaneous remediation of contaminated sediments and the overlying water body.

Release of contaminants from sediments has been one of the main pollution sources causing eutrophication and malodorous black of ponds. In this study, an iron-rich substrate (IRS) was developed based on iron­carbon micro-electrolysis and applied for simultaneous sediments and overlying water remediation. IRS obtained high ammonia and phosphate adsorption capacities (Langmuir isotherm) of 13.02 and 18.12 mg·kg-1, respectively. In the 90-day long-term remediation, IRS reduced NH4+-N, PO43--P, organic-N, organic-P, TN and TP in overlying water by 48.6%, 97.9%, 34.2%, 67.1%, 53.2% and 90.4%, respectively. In sediments, IRS reduced NO3--N, NH4+-N and organic-N by 98.5%, 26.5% and 6.3%, respectively. The unstable P-compounds (i.e., organic-P, Ca-bounded-P and labile-P) were effectively transferred (20.1%, 54.3% and 98.2%, respectively) into inert P-compounds (i.e., Fe-bounded-P and residual-P). Meanwhile, flux rates of nitrogen and phosphorus from sediments to overlying water were reduced from 7.02 to 4.92 mg·m-2·d-1 (by 29.9%) and from 7.42 to 2.21 mg·m-2·d-1 (by 70.2%), respectively. Due to micro-electrolysis, Fe2+/Fe3+/[H] were in-situ generated from IRS and NO3--N was effectively reduced. Additionally, the generation of O2· was promoted by Fe2+/[H] and strengthened the NH4+-N, organic-N/P oxidation. Fe3+ enhanced the immobilization of PO43- (e.g., as FePO4·H2O and FenPO4(OH)3n-3). The released Fe2+/Fe3+ from IRS were finally stabilized as poorly reactive sheet silicate (PRS)-Fe and magnetite-Fe in the sediments and hardly showed side effect to sediments and water body. The developed IRS obtained advantages of high efficiency, ecologically safe and cost-effective in contaminated sediments and overlying water remediation.

An oxic/anoxic-integrated and Fe/C micro-electrolysis-mediated vertical constructed wetland for decentralized low-carbon greywater treatment.

The treatment of decentralized low-carbon greywater in rural area, particularly in cold weather, remains a challenge. Oxic/anoxic process and Fe/C micro-electrolysis were incorporated into vertical constructed wetland to develop ME-(O/A)CW for practical decentralized low-carbon greywater treatment. ME-(O/A)CW provided NH4+-N, TN, TP and COD removal of 94.3%, 86.2%, 98.0% and 92.7%, respectively, at hydraulic loading rate of 0.9 m3/(m2·d) under low ambient temperature of -11.5 to 8.0 °C. Effective nitrification, phosphorus-accumulating and organic-degradation were proceeded in the aerobic layers and efficient H2-/Fe2+-mediated autotrophic denitrification and Fe3+-based phosphorus immobilization were developed in the anaerobic layers through in-situ H2-/Fe2+-supply by Fe/C micro-electrolysis. AOB (e.g. Nitrosomonadales), NOB/PAOs (e.g. Nitrospira), autotrophic denitrificans (e.g. Thiobacillus, Hydrogenophaga and Sulfurimonas), heterotrophic denitrificans (e.g. Denitratisoma) and Fe(II)-oxidizing bacteria (e.g. Ferritrophicum) dominated ME-(O/A)CW and confirmed the reaction mechanisms. The developed ME-(O/A)CW presented significant potential in the practical application for decentralized low-carbon greywater treatment under low ambient temperature.

Iron-carbon galvanic cells strengthened anaerobic/anoxic/oxic process (Fe/C-A2O) for high-nitrogen/phosphorus and low-carbon sewage treatment.

The treatment of sewage with high-nitrogen/-phosphorus and low-carbon remains a challenge. A novel iron-carbon galvanic cells strengthened anaerobic/anoxic/oxic process (Fe/C-A2O) was developed for high-nitrogen/-phosphorus and low-carbon sewage treatment. The cost-effective iron-scraps (ISs) was recycled as Fe(0)-source under the mediation of Fe/C galvanic cell reaction to develop effective Fe(0)-oxidizing autotrophic-denitrification and -dephosphorization. Utilizing practical high-nitrogen/-phosphorus and low-carbon sewage as target wastewater, the performance, impact factors, contribution of Fe/C galvanic cell reactions, microbial characteristics, strengthening mechanisms, and application potential of Fe/C-A2O process were investigated. The Fe/C-A2O process achieved high TN and TP removal efficiencies of 92.0 ± 1.3% and 97.2 ± 0.9% with removal loads of 0.176 ± 0.002 kg TN/(m3·d) and 0.017 ± 0.002 kg TP/(m3·d), respectively. Optimal HRT of 12 h, DO of 4.0-4.5 mg/L, and reflux-ratio of 4:1 were obtained, and no sludge-reflux was required. Autotrophic-denitrification and -dephosphorization supported by the Fe/C galvanic cell reactions contributed 63.1% and 75.3% of TN and TP removal, respectively. Microbial characterization revealed the dominance of autotrophic denitrifiers (e.g., Thiobacillus), AOB (e.g., Nitrosomonas), NOB (e.g., Nitrospira), and heterotrophic denitrifiers (e.g., Zoogloea). The mechanism analysis demonstrated that Fe/C galvanic cells strengthened nitrogen removal by raising Fe2+/H2-supported autotrophic denitrification; and strengthened dephosphorization by introducing Fe3+-based PO43--precipitation and enhancing the denitrifying phosphate-accumulation by denitrifying phosphate-accumulating organisms (DPAOs). Based on the efficiency and cost evaluation, the ISs-based Fe/C-A2O process showed significant application potential as an upgrade strategy for traditional A2O process in advanced high-nitrogen/phosphorus and low-carbon sewage treatment.

Application potential of simultaneous nitrification/Fe0-supported autotrophic denitrification (SNAD) based on iron-scraps and micro-electrolysis.

Oxygen has not been purposely introduced to the autotrophic denitrification systems and simultaneous nitrification/autotrophic denitrification (SNAD) has not been proposed. In this study, oxygen was introduced into a micro-electrolysis-enhanced Fe0-supported autotrophic denitrification (mFe0AD) system. The nitrogen removal performance was investigated and the application potential of iron-scraps-supported simultaneous nitrification/mFe0AD was evaluated. The results showed that Fe0AD was surprisingly enhanced by oxygen together with nitrification at average dissolved oxygen (DO) of 0.08-1.56 mg/L. The ammonia oxidizing bacterial, nitrite oxidizing bacteria, facultative autotrophic denitrificans, and iron compounds transformation bacteria were markedly enriched. Average denitrification rate shifted from 0.116 to 0.340 kg N/(m3·d) with increase of average total nitrogen removal efficiency from 31.4% to 90.5%. Oxygen could enhance the biological conversion and storage of iron compounds, which was capable of reducing the coating of Fe0 surface.The accelerating of oxygen on  Fe0 passivation appeared when increasing the average DO from 1.56 to 2.17 mg/L. Therefore, the SNAD was recommended to be operated at the DO range of 0.08-1.56 mg/L. ME significantly enhanced Fe0AD, and the utilization of iron-scraps reduced its cost. The denitrification rate is comparable with methanol supported heterotrophic denitrification with 58.9% reduction on the cost. The iron-scraps supported SNAD is competitive in both denitrification rate and costs in the ammonia contaminated low-carbon water treatment.

Enhanced Degradation of Sulfamethoxazole (SMX) in Toilet Wastewater by Photo-Fenton Reactive Membrane Filtration.

Pharmaceutical residuals are increasingly detected in natural waters, which made great threat to the health of the public. This study evaluated the utility of the photo-Fenton ceramic membrane filtration toward the removal and degradation of sulfamethoxazole (SMX) as a model recalcitrant micropollutant. The photo-Fenton catalyst Goethite (α-FeOOH) was coated on planar ceramic membranes as we reported previously. The removal of SMX in both simulated and real toilet wastewater were assessed by filtering the feed solutions with/without H2O2 and UV irradiation. The SMX degradation rate reached 87% and 92% respectively in the presence of UV/H2O2 for the original toilet wastewater (0.8 ± 0.05 ppb) and toilet wastewater with a spiked SMX concentration of 100 ppb. The mineralization and degradation by-products were both assessed under different degradation conditions to achieve deeper insight into the degradation mechanisms during this photo-Fenton reactive membrane filtration. Results showed that a negligible removal rate (e.g., 3%) of SMX was obtained when only filtering the feed solution through uncoated or catalyst-coated membranes. However, the removal rates of SMX were significantly increased to 67% (no H2O2) and 90% (with H2O2) under UV irradiation, respectively, confirming that photo-Fenton reactions played the key role in the degradation/mineralization process. The highest apparent quantum yield (AQY) reached up to approximately 27% when the H2O2 was 10 mmol·L-1 and UV254 intensity was 100 µW·cm-2. This study lays the groundwork for reactive membrane filtration to tackle the issues from micropollution.

Enhancement of anaerobic digestion effluent treatment by microalgae immobilization: Characterized by fluorescence excitation-emission matrix coupled with parallel factor analysis in the photobioreactor.

The bacterial-microalgal consortium has been investigated to anaerobic digestion effluent (ADE) treatment in the photobioreactor (PBR). However, the high concentrations of nutrients reduced the ADE treatment efficiency and the transformation of organic pollutants in PBR was still unclear. In this study, two-sequencing batch PBRs were operated with suspended Microcystis aeruginosa (M. aeruginosa, SMA) and immobilized M. aeruginosa (IMA) to compare the ADE treatment performance. Fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) was conducted to identify organics degradations. The results showed that the proportion of living M. aeruginosa cell (86.4%) in PBR (IMA) was highly significant (p < 0.05) higher than that in PBR (SMA) (75.2%). This indicated immobilized microalgae beads enhanced the resistance to the high concentration of nutrients in PBR (IMA). EEM-PARAFAC analysis displayed the biodegradation order in the bacterial-microalgal consortium system was humic-like substances > tyrosine-like substances > tryptophan-like substances. The removals of humic-like matters (94.05 ±â€¯0.92%) and tyrosine-like matters (91.13 ±â€¯2.49%) in PBR (IMA) were significantly (p < 0.01) higher than those in PBR (SMA). Notably, the average removals of nutrients in PBR (IMA) were significantly (p < 0.05) higher than those in PBR (SMA). This result verified that microalgae immobilization benefitted nutrients removals with 93.05 ±â€¯1.45% of NH4+-N and complete PO43--P removal in PBR (IMA). Moreover, the enrichment of functional genera Flavobacterium and Opitutus contributed to decreasing the organics loadings and strengthening the ADE treatment performance. Therefore, this study verified microalgae immobilization enhanced the actual ADE treatment. Additionally, fluorescent organic pollutants degradations were further evaluated by EEM-PARAFAC analysis in the bacterial-microalgal consortium.

Combination with catalyzed Fe(0)-carbon microelectrolysis and activated carbon adsorption for advanced reclaimed water treatment: simultaneous nitrate and biorefractory organics removal.

A process combining catalyzed Fe(0)-carbon microelectrolysis (IC-ME) with activated carbon (AC) adsorption was developed for advanced reclaimed water treatment. Simultaneous nitrate reduction and chemical oxygen demand (COD) removal were achieved, and the effects of composite catalyst (CC) addition, AC addition, and initial pH were investigated. The reaction kinetics and reaction mechanisms were calculated and analyzed. The results showed that CC addition could enhance the reduction rate of nitrate and effectively inhibit the production of ammonia. Moreover, AC addition increased the adsorption capacity of biorefractory organic compounds (BROs) and enhanced the degradation of BRO. The reduction of NO3--N at different pH values was consistently greater than 96.9%, and NH4+-N was suppressed by high pH. The presence of CC ensured the reaction rate of IC-ME at high pH. The reaction kinetics orders and constants were calculated. Catalyzed iron scrap (IS)-AC showed much better nitrate reduction and BRO degradation performances than IS-AC and AC. The IC-ME showed great potential for application to nitrate and BRO reduction in reclaimed water.