Revitalizing plastic wastes employing bio-circular-green economy principles for carbon neutrality.

The use of plastics has become deeply ingrained in our society, and there are no indications that its prevalence will decrease in the foreseeable future. This article provides a comprehensive overview of the global plastic waste disposal landscape, examining it through regional perspectives, various management technologies (dumping or landfilling, incineration, and reuse and recycling), and across different sectors including agriculture and food, textile, tourism, and healthcare. Notably, this study compiles the findings on life-cycle carbon footprints associated with various plastic waste management practices as documented in the literature. Employing the bio-circular-green economy model, we advocate for the adoption of streamlined and sustainable approaches to plastic management. Unique management measures are also discussed including the utilization of bioplastics combined with smart and efficient collection processes that facilitate recycling, industrial composting, or anaerobic digestion. Moreover, the integration of advanced recycling methods for conventional plastics with renewable energy, the establishment of plastic tax and credits, and the establishment of extended producer responsibility are reviewed. The success of these initiatives relies on collaboration and support from peers, industries, and consumers, ultimately contributing to informed decision-making and fostering sustainable practices in plastic waste management.

Development of yeast and microalgae consortium biofilm growth system for biofuel production.

Background: The current study aimed to develop a laboratory-scale biofilm photobioreactor system for biofuel production. Scope & Approach: During the investigation, Jute was discovered to be the best, cheap, hairy, open-pored supporting material for biofilm formation. Microalgae & yeast consortium was used in this study for biofilm formation. Conclusion: The study identified microalgae and yeast consortium as a promising choice and ideal partners for biofilm formation with the highest biomass yield (47.63 ± 0.93 g/m2), biomass productivity (4.39 ± 0.29 to 7.77 ± 0.05 g/m2/day) and lipid content (36%) over 28 days cultivation period, resulting in a more sustainable and environmentally benign fuel that could become a reality in the near future.

Bio-oil and biochar production from Ageratum conyzoides using triple-stage hydrothermal liquefaction and utilization of biochar in removal of multiple heavy metals from water.

Production of low-cost biomass and its utilization for producing cost effective and eco-friendly bioenergy as well as for removing heavy metals from water can be explored as an approach to meet the sustainable development goals. In light of the above-mentioned study, hydrothermal liquefaction (HTL) of Billy goat weed (BGW; Ageratum conyzoides) was carried out to produce bio-oil. In addition, the residual biochar from the HTL process was activated to obtain Act-BC and was further modified to produce MnO2-loaded biochar (Act-BC@MnO2-25%). The HTL of BGW was done at three different temperatures, i.e., 250 °C, 350 °C and 450 °C in a high-pressure batch reactor to maximize the bio-oil yield. Also, two different HTL methods i.e., single-stage HTL and triple-stage HTL of BGW were compared and discussed in detail. The bio-oil obtained via the triple-stage HTL was rich in carbon, hydrogen, and nitrogen. It also showed a higher heating value (HHV) and bio-oil yield (46%) than the single-stage. The residual biochar obtained at 450 °C (Act-BC) and MnO2 modified (Act-BC@MnO2-25%) were then tested to adsorb multiple heavy metal (i.e., Pb(II), Cd(II), Cu(II), and Ni(II)) from water. The kinetics data obtained from the adsorption experiment with Act-BC@MnO2-25% were well fitted to PSO kinetics model. The isotherm data were well aligned with the Langmuir model; the adsorption capacity of Act-BC@MnO2-25% was estimated to be 198.70 ± 11.40 mg g-1, 93.70 ± 6.60 mg g-1, 78.90 ± 7.20 mg g-1 and 30.50 ± 2.10 mg g-1 for Pb(II), Cd(II), Cu(II), and Ni(II), respectively. Furthermore, Act-BC@MnO2-25% remained active for metal ions absorption even after six consecutive uses. The result obtained from this study clearly demonstrates that the triple-stage HTL of BGW is a promising technology to achieve both remediation of metal-contaminated water and production of bioenergy.

Evaluation of vertical distribution characteristics of microplastics under 20 µm in lake and river waters in South Korea.

Following the alarming reports of microplastic pollution in the marine environment, increased attention has been given to microplastics in other environmental media. Despite the attention, there is limited research available on the depth-distribution of microplastics in freshwater. Specifically, in the case of water sources used for drinking or tap, the height of intake facilities varies, and it is highly likely that there is a correlation between the vertical distribution of microplastics and these water intake structures. Further, because the size of microplastics varies widely in the environment, the commonly used sampling devices are not suitable for selectively extracting microplastics without causing cross-contamination. Thus, we developed a suitable device for microplastics of size 5-20 µm and studied microplastic distribution in freshwater at various depths by considering various types of microplastics and aqueous systems. Lake and river, two major water sources, were selected for the study of microplastics distribution in water system. The microplastic distribution characteristics in both water systems showed that polypropylene and polyethylene were the most abundant across all depths because of their production volume. Plastic types with higher density were found only at the lower layers, and polystyrene was found in the upper layers because of the environmental effects on its buoyancy caused pore diameter and surface area. The lake and river had higher microplastic distribution in the lower layer and upper layer, respectively. This was because the flow rate in river was higher than that of lake. The higher flow rate reduced the settling velocity in river. Thus, hydrodynamic stability influences the vertical distribution and concentrations of microplastics in the water systems. These results are expected to be used for understanding the behavioral characteristics of microplastics in water systems and to manage water sources.

A phyco-nanobionics biohybrid system for increased carotenoid accumulation in C. sorokiniana UUIND6.

Recent advancements in "phyco-nanobionics" have sparked considerable interest in the ability of microalgae to synthesize high-value natural bioactive compounds such as carotenoid pigments, which have been highlighted as an emergent and vital bioactive compound from both industrial and scientific perspectives. Such bioactive compounds are often synthesized by either altering the biogenetic processes existing in living microorganisms or using synthetic techniques derived from petroleum-based chemical sources. A bio-hybrid light-driven cell factory system was established herein by using harmful macroalgal bloom extract (HMBE) and efficient light-harvesting silver nanoparticles (AgNPs) to synthesize HMBE-AgNPs and integrating the synthesized HMBE-AgNPs in various concentrations (1, 2.5, 5 and 10 ppm) into the microalgae C. sorokiniana UUIND6 to improve the overall solar-to-chemical conversion efficiency in carotenoid pigment synthesis in microalgae. The current study findings found high biocompatibility of 5 ppm HMBE-AgNP concentration that can serve as a built-in photo-sensitizer and significantly improve ROS levels in microalgae (6.75 ± 0.25 µmol H2O2 g-1), thus elevating total photosynthesis resulting in a two-fold increase in carotenoids (457.5 ± 2.5 µg mL-1) over the native microalgae without compromising biomass yield. NMR spectroscopy was additionally applied to acquire a better understanding of pure carotenoids derived from microalgae, which indicated similar peaks in both spectra when compared to ß-carotene. Thus, this well-planned bio-hybrid system offers a potential option for the cost-effective and long-term supply of these natural carotenoid bio-products.

Chitosan cross-linked ß-cyclodextrin polymeric adsorbent for the removal of perfluorobutanesulfonate from aqueous solution: adsorption kinetics, isotherm, and mechanism.

The existence of per- and polyfluoroalkyl substances (PFASs) in water is of serious interest due to their toxic, bioaccumulative, and persistent nature, and adsorption is an effective approach for the PFASs removal. In the present study, we developed a polymeric adsorbent by cross-linking chitosan and ß-cyclodextrin using glutaraldehyde (Chi-Glu-ß-CD) and evaluated its removal performance for perfluorobutanesulfonate (PFBS) from water. The results indicate that the performance was highly affected by solution pH; under a more acidic condition (e.g., pH 2.0), a higher removal efficiency was detected, and faster adsorption kinetics was observed with the rate constant (k2) of 0.001 ± 3×10-4 g mg-1 min-1. Adsorption isotherm data agreed to the Sips model with a maximum heterogeneous adsorption capacity of 135.70 ± 25.70 mg g-1, probably due to protonated amine (NH+) and electron-deficient ß-CD cavities. The adsorption mechanism was confirmed using energy dispersive X-ray and Fourier transform infrared (FTIR) spectroscopy, showing the role of electrostatic attractions between the protonated amine and the negatively charged PFBS molecule (especially, with sulfonate side (N-H--O-S)) and host-guest inclusion formations with ß-CD cavity in adsorption. Additionally, the synthesized adsorbent was recovered using methanol without any significant decline in adsorption efficiency even after four continuous adsorption/desorption cycles. All these findings suggested that the Chi-Glu-ß-CD composite could be a promising adsorbent in the removal of PFBS from water.

Evaluation of the dual-process approach for in-situ groundwater arsenic removal.

While the worldwide distribution of geogenic arsenic (As)-affected groundwater is highly overlapped with the areas with abundant groundwater, utilization of As-contained groundwater is an inevitable compromise in those areas where surface water is not enough for irrigation. Since the occurrence of As in groundwater is often accompanied by high iron (Fe) contents, the facilitation of As and Fe precipitation without adding additional oxidizers and adsorbents is considered an environmental-friendly approach to removing As in groundwater. In the present study, the oxidation/filtration dual-process with sprinkling height of 25 cm and 120 kg filter media efficiently increased the dissolved oxygen (DO) concentration (0.36-1.52 mg/L) and oxidation-reduction potential (ORP) (24-63 mV), which facilitated the formation of Fe oxides and As co-precipitation. The correlation of As removal efficiencies with their respective flow rates indicated that a decrease in groundwater Fe and an increase of Fe in sands and gravels filters as the flow rate increased evidenced the rapid oxidation of Fe to form the Fe hydroxides. In a 40-hour continuous aeration/filtration operation, As and Fe concentrations in groundwater were reduced by 79.5% and 64.88% within 40 hrs, respectively. The ease of filter replacement and cost-effectiveness in operation can be the major attractions and innovations for future field practices.

Hydrogenotrophs-Based Biological Biogas Upgrading Technologies.

Biogas produced from anaerobic digestion consists of 55-65% methane and 35-45% carbon dioxide, with an additional 1-2% of other impurities. To utilize biogas as renewable energy, a process called biogas upgrading is required. Biogas upgrading is the separation of methane from carbon dioxide and other impurities, and is performed to increase CH4 content to more than 95%, allowing heat to be secured at the natural gas level. The profitability of existing biogas technologies strongly depends on operation and maintenance costs. Conventional biogas upgrading technologies have many issues, such as unstable high-purity methane generation and high energy consumption. However, hydrogenotrophs-based biological biogas upgrading offers an advantage of converting CO2 in biogas directly into CH4 without additional processes. Thus, biological upgrading through applying hydrogenotrophic methanogens for the biological conversion of CO2 and H2 to CH4 receives growing attention due to its simplicity and high technological potential. This review analyzes the recent advance of hydrogenotrophs-based biomethanation processes, addressing their potential impact on public acceptance of biogas plants for the promotion of biogas production.

Simultaneous capturing of mixed contaminants from wastewater using novel one-pot chitosan functionalized with EDTA and graphene oxide adsorbent.

The emergence of inorganic and organic contaminants has raised great concerns owing to their adverse impact on human health and ecological security. Herein, first time one-pot process was applied for chitosan (CS) functionalization using graphene oxide (GO) and ethylenediaminetetraacetic acid (EDTA) for simultaneous capturing of toxic inorganic (lead (Pb2+) and cadmium (Cd2+)) and organic (ciprofloxacin (CIP) and sildenafil (SDF)) contaminants from wastewater. In this approach, we believe that CS would work as a backbone, GO would capture both inorganic and organic contaminants via electrostatic interactions, while EDTA would make complexation with heavy metals. Various parameters including pH, reaction time, concentration, reusability etc. were evaluated to achieve the best experimental result in monocomponent system. The prepared adsorbent displayed an excellent monolayer adsorption capacity of 351.20 and 264.10 mg g-1 for Pb2+ and Cd2+, respectively, while a heterogeneous sorption capacity of 75.40 and 40.90 mg g-1 for CIP and SDF, respectively. The kinetics data fitted well to Pseudo-second order (PSO) kinetics model for both types of contaminants and gave faster interaction towards metal ions (higher k2) than organic contaminants. Experimental results showed excellent adsorption efficiencies at environmental levels in the capturing of both inorganic and organic contaminants at the same time from polluted water. The capturing mechanism of both types of contaminants was explained by elemental mapping, EDS, and FT-IR spectra. Overall, easy synthesis, excellent capturing capacity, and reusability imply that the prepared adsorbent has a sufficient potential for the treatment of co-existing toxic contaminants in water.

Synthesis of EDTA-functionalized graphene oxide-chitosan nanocomposite for simultaneous removal of inorganic and organic pollutants from complex wastewater.

Discharging of inorganic and organic pollutants creates a serious threat to the human health and the environment. In the current work, we have synthesized Ethylenediaminetetraacetic acid (EDTA) functionalized graphene oxide-chitosan nanocomposite (GO-EDTA-CS) for simultaneous removal of inorganic (i.e., mercury (Hg(II) and copper (Cu(II)) and organic pollutants (i.e., methylene blue (MB) and crystal violet (CV)) from wastewater via adsorption process. The structural, functional, morphological, elemental compositions, surface area and thermal properties of the synthesized nanocomposite were identified using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Brunauer-Emmett-Teller (BET), and thermogravimetric analyzer (TGA), respectively. Different batch adsorption experiments such as pH effect, contact time, initial pollutants concentration, reusability etc. were studied in monocomponent system to optimize the results. The adsorption process apparently followed pseudo-second-order (PSO) kinetics for both pollutants, however the adsorption kinetics was also explained by the intra-particle diffusion model. The isotherm data for both metals ions and dyes were well fit by the Langmuir isotherm model. The maximum adsorption capacities of the adsorbent were determined 324 ± 3.30 130 ± 2.80, 141 ± 6.60, and 121 ± 3.50 mg g-1 for Hg(II), Cu(II), MB, and CV, respectively. The excellent adsorption capacity was attributed to the availability of various active functional groups (e.g., -COOH, -OH, -NH2, etc.) on the adsorbent. The EDS, elemental mapping and FTIR analysis performed before and after the adsorption of heavy metals and dyes by GO-EDTA-CS confirmed the simultaneous adsorption of the pollutants. Moreover, GO-EDTA-CS could maintain its adsorption capacity for both inorganic and organic pollutants even after seven cycles of adsorption-desorption, indicating itself a promising adsorbent for practical wastewater treatment containing both inorganic and organic toxic pollutants.

Multifunctional ß-Cyclodextrin-EDTA-Chitosan polymer adsorbent synthesis for simultaneous removal of heavy metals and organic dyes from wastewater.

Heavy metals and organic dyes are the major source of water pollution. Herein, a trifunctional ß-cyclodextrin-ethylenediaminetetraacetic acid-chitosan (ß-CD-EDTA-CS) polymer was synthesized using an easy and simple chemical route by the reaction of activated ß-CD with CS through EDTA as a cross-linker (amidation reaction) for the removal of inorganic and organic pollutants from aqueous solution under different parameters such as pH, time effect, initial concentration, reusability, etc. The synthesized adsorbent was characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, field scanning electron microscopy, energy dispersive spectroscopy, Brunauer-Emmett-Teller (BET), thermogravimetric analyzer techniques to investigate their structural, functional, morphological, elemental compositions, surface area and thermal properties, respectively. Two types of heavy metals, i.e., mercury (Hg2+) and cadmium (Cd2+), and three organic dyes, i.e., methylene blue (MB), crystal violet (CV) and safranin O (SO) were chosen as inorganic and organic pollutants, respectively, to study the adsorption capacity of ß-CD-EDTA-CS in aqueous solution. The ß-CD-EDTA-CS shows monolayer adsorption capacity 346.30 ± 14.0 and 202.90 ± 13.90 mg g-1 for Hg2+ and Cd2+, respectively, and a heterogeneous adsorption capacity 107.20 ± 5.70, 77.40 ± 5.30 and 55.30 ± 3.60 mg g-1 for MB, CV and SO, respectively. Kinetics results followed pseudo-second order (PSO) kinetics behavior for both metal ions and dyes, and higher rate constants values (0.00161-0.00368 g mg-1 min-1) for dyes confirmed the cavitation of organic dyes (physisorption). In addition, we have also demonstrated the performance of ß-CD-EDTA-CS for the of four heavy metals Hg2+, Cd2+, Ni2+, and Cu2+ and three dyes MB, CV, and SO in secondary treated wastewater. Findings of this study indicate that ß-CD-EDTA-CS simple and essay to synthesize and can be use in wastewater treatment.

Simultaneous Removal of Heavy Metals and Ciprofloxacin Micropollutants from Wastewater Using Ethylenediaminetetraacetic Acid-Functionalized ß-Cyclodextrin-Chitosan Adsorbent.

The current study pertains to the synthesis of an EDTA-functionalized ß-cyclodextrin-chitosan (ß-CD-CS-EDTA) composite via a two-step process for the adsorptive removal of toxic heavy metallic ions (i.e., Pb(II), Cu(II), and Ni(II)) and antibiotic micropollutant, i.e., ciprofloxacin (CIP), from water. Different batch adsorption experiments such as pH, reaction time and initial pollutant concentration effects were carried out to identify the adsorption condition to attain the maximum removal efficiency. Kinetics results fit well with the pseudo-second order (PSO) kinetics model for both inorganic and organic pollutants. However, adsorption of heavy metal ions to the adsorbent was faster than that of CIP. Isotherms results showed excellent monolayer adsorption capacities of 330.90, 161, and 118.90 mg g-1 for Pb(II), Cu(II), and Ni(II), respectively, with a heterogeneous adsorption capacity of 25.40 mg g-1 for CIP. The adsorption mechanism was investigated using energy dispersive X-ray (EDX), elemental mapping, and Fourier transform infrared (FTIR) techniques. More significantly, the synthesized adsorbent gave good removal efficiencies when it was applied to simultaneously adsorb metal ions and CIP from real wastewater. Furthermore, excellent reusability could be obtained, making it a viable alternative to remove the inorganic and organic micropollutants for wastewater treatment.

Complete Genome Sequence of Methanothermobacter sp. Strain THM-1, a Thermophilic and Hydrogenotrophic Methanogen Isolated from an Anaerobic Reactor in South Korea.

Methanothermobacter sp. strain THM-1, a thermophilic and hydrogenotrophic methanogen, was isolated from an anaerobic reactor enriched with thermophilic methanogens. The genome of THM-1 shares 98.81% of its sequence with Methanothermobacter wolfeii isolate SIV6 and consists of 1,724,502 bp with 1,665 protein-coding genes, 50 noncoding RNAs, and a GC content of 48.6%.

Influence of activated biochar pellet fertilizer application on greenhouse gas emissions and carbon sequestration in rice (Oryza sativa L.) production.

Supplemental activated biochar pellet fertilizers (ABPFs) were evaluated as a method to sequester carbon and reduce greenhouse gas (GHG) emissions, and improve rice production. The evaluated treatments were a control (standard cultivation method, no additives applied), activated rice hull biochar pellets with 40% of N (ARHBP-40%), and activated palm biochar pellets with 40% of N (APBP-40%). The N supplied by the ARHBP-40% and APBP-40% treatments reduced the need for supplemental inorganic nitrogen (N) fertilizer by 60 percent. The ARHBP-40% treatment sequestered as much as 1.23 tonne ha-1 compared to 0.89 tonne ha-1 in the control during the rice-growing season. In terms of greenhouse gas (GHG) emissions, CH4 emissions were not significantly different (p > 0.05) between the control and the ARHBP-40%, while the lowest N2O emissions (0.002 kg ha-1) were observed in the ARHBP-40% during the crop season. Additionally, GHG (CO2-equiv.) emissions from the ARHBP-40% application were reduced by 10 kg ha-1 compared to the control. Plant height in the control was relatively high compared to others, but grain yield was not significantly different among the treatments. The application of the ARHBP-40% can mitigate greenhouse gas emissions and enhance carbon sequestration in crop fields, and ABPFs can increase N use efficiency and contribute to sustainable agriculture.

Anaerobic co-digestion of agricultural wastes toward circular bioeconomy.

A huge amount of agricultural wastes and waste activated-sludge are being generated every year around the world. Anaerobic co-digestion (AcD) has been considered as an alternative for the utilization of organic matters from such organic wastes by producing bioenergy and biochemicals to realize a circular bioeconomy. Despite recent advancement in AcD processes, the effect of feedstock compositions and operating conditions on the biomethane production processe has not been critically explored. In this paper, we have reviewed the effects of feedstock (organic wastes) characteristics, including particle size, carbon-to-nitrogen ratio, and pretreatment options, on the performance of an anaerobic digestion process. In addition, we provided an overview of the effect of key control parameters, including retention time, temperature, pH of digestate, volatile fatty acids content, total solids content, and organic loading rate. Lastly, based on the findings from the literature, we have presented several perspectives and prospects on priority research to promote AcD to a steppingstone for a circular bioeconomy.

Effect of palladium on the black mass-based catalyst prepared from spent Zn/Mn alkaline batteries for catalytic combustion of volatile organic compounds.

A large amount of spent batteries is produced annually. When spente batteries are buried, their harmful components may contaminate soil and water. Therefore, recycling of spent batteries is essential for environmental reasons. We evaluated the BM (black mass) of spent Zn/Mn alkaline batteries as a catalyst substance for the catalytic combustion of volatile organic compounds (VOCs: benzene, toluene, and o-xylene). The SBM catalyst (black mass-based catalyst) was prepared by treating BM with 0.1 N of sulfuric acid solution. Major elements of the SBM catalyst were manganese, zinc, iron, aluminum, potassium, and sodium except for carbon. In addition, to find out the additive effect of palladium on the SBM catalyst, we prepared the Pd/SBM catalysts using a conventional impregnation method. We investigated the physicochemical properties of the SBM and Pd/SBM catalysts by instrumental analysis. Benzene, toluene, and o-xylene (BTX) were oxidized completely over the SBM catalyst at reaction temperatures less than 410, 340, and 410 °C, respectively (gas hourly space velocity: 40,000 h-1). As expected, for the Pd/SBM catalysts, increasing the palladium loading on the SBM from 0.1 wt% to 1.0 wt% increased the conversions of BTX. In the 1.0 wt% Pd/SBM catalyst, the reaction temperatures for catalytic combustion of BTX were greatly reduced to 310, 260, and 250 °C, respectively (gas hourly space velocity: 40,000 h-1). Instrumental analysis indicated that the increase in activity by adding palladium resulted from the active ingredient (palladium oxide: PdO) and better redox properties.

Effect of biochar amendment on compost quality, gaseous emissions and pathogen reduction during in-vessel composting of chicken manure.

Because of rapid development in the livestock industry, the production of chicken manure has subsequently increased, which may contribute to environmental pollution. In this regard, in-vessel composting of biochar amended chicken manure and sawdust mixtures was investigated to find out the effect of biochar at the ratios of 0% (control), 3% (T1), 5% (T2), and 10% (T3) on ammonia and greenhouse gases (GHGs) emission, compost quality, pathogenic contaminants and phytotoxicity. The composting process was performed in 100-L, pilot-scale, plastic, cylindrical vessels for 50 days. The addition of biochar (3%, 5%, and 10%) increased the thermophilic temperature with a significant reduction in gaseous emissions (ammonia and CO2), microbial pathogens (Escherichia coli and Salmonella sp.), and phytotoxicity (Lepidium sativum seed germination assay) compared with that of the control compost products. However, according to the obtained results with in-vessel composting, the amendment of 10% biochar showed the most significant effects concerning the quality of the compost nutrients. The study reveals that the addition of biochar during in-vessel chicken manure composting is beneficial in the reduction of gaseous emissions and pathogenic microorganisms apart from improvement in plant nutrients.

Contribution of sewage to occurrence of phosphodiesterase-5 inhibitors in natural water.

Phosphodiesterase-5 inhibitors (PDE-5i, such as Sildenafil, Tadalafil and Vardenafil, mainly prescribed to treat erectile dysfunction) and their generic drug equivalents have been widely marketed and consumed in Korea. From the concentrations detected in wastewater, we could deduce that relatively large amounts of PDE-5i were consumed without a legal prescription. Thus, PDE-5i's presence in the environment via sewage is unavoidable, and their environmental fate within a sewage treatment plant (STP) should be evaluated. In this study, we investigated the occurrence of three PDE-5i analogs in the influent and effluent of two STPs and the receiving water bodies. The PDE-5i concentration in total reached 62 ± 12 (STP#1) and 88 ± 37 ng L-1 (STP#2) in the sewage influent; about 70% of it was Sildenafil in both STPs. However, they were hardly removed by the STPs as the removal efficiency of the STPs was less than 10% ± 5%. Therefore, the pharmaceuticals were detected in the receiving water (lower than 7 ng L-1as a total amount) and the concentration slightly increased downstream of the STPs. A simple mass balance model applied for the compounds in the STP effluent and receiving water bodies also confirmed that the discharged PDE-5i were quite persistent. Lastly, we identified temporal and regional patterns in the consumption of the drugs from daily variations of PDE-5i in the influent to these two STPs. For instance, the levels of PDE-5i in the sewage significantly increased on weekends (from Friday to Saturday), and especially in the area where adult-entertainment businesses are common. We estimated that the amount of PDE-5i consumption in this area was 31% higher than that in the area with fewer nightlife spots. Considering that they are pharmaceutically active and resistant to treatment processes within an STP, it is advised that a regular monitoring and management program for PDE-5i should be developed to prevent the discharge of the pharmaceuticals into the water environment.

Non-conventional water reuse in agriculture: A circular water economy.

Due to the growing and diverse demands on water supply, exploitation of non-conventional sources of water has received much attention. Since water consumption for irrigation is the major contributor to total water withdrawal, the utilization of non-conventional sources of water for the purpose of irrigation is critical to assuring the sustainability of water resources. Although numerous studies have been conducted to evaluate and manage non-conventional water sources, little research has reviewed the suitability of available water technologies for improving water quality, so that water reclaimed from non-conventional supplies could be an alternative water resource for irrigation. This article provides a systematic overview of all aspects of regulation, technology and management to enable the innovative technology, thereby promoting and facilitating the reuse of non-conventional water. The study first reviews the requirements for water quantity and quality (i.e., physical, chemical, and biological parameters) for agricultural irrigation. Five candidate sources of non-conventional water were evaluated in terms of quantity and quality, namely rainfall/stormwater runoff, industrial cooling water, hydraulic fracturing wastewater, process wastewater, and domestic sewage. Water quality issues, such as suspended solids, biochemical/chemical oxygen demand, total dissolved solids, total nitrogen, bacteria, and emerging contaminates, were assessed. Available technologies for improving the quality of non-conventional water were comprehensively investigated. The potential risks to plants, human health, and the environment posed by non-conventional water reuse for irrigation are also discussed. Lastly, three priority research directions, including efficient collection of non-conventional water, design of fit-for-purpose treatment, and deployment of energy-efficient processes, were proposed to provide guidance on the potential for future research.

Degradation synergism between sonolysis and photocatalysis for organic pollutants with different hydrophobicity: A perspective of mechanism and application for high mineralization efficiency.

Despite extensive studies, the fundamental understanding of synergistic mechanisms between sonolysis and photocatalysis for the abatement of persistent organic pollutants (POPs) remains uncertain. As different phases formed under ultrasound irradiation, hydrophilic POPs, sulfamethoxazole (SMX, Kow: 0.89), predominantly resides in bulk liquid and is ineffectively degraded by sonolysis (kUS = 3.33 × 10-3 min-1) since <10% of hydroxyl radicals (·OH) formed at the gas-liquid interface of cavitation is diffused into the bulk, whereas the other fraction rapidly recombines into hydrogen peroxide (H2O2). This study provides a proof-of-concept for the mechanism by presenting various analytical results, endorsing the synergistic role of photoexcited electrons in splitting sonolysis-induced H2O2 into ·OH, particularly in the bulk phase. In a sonophotocatalytic system, the hydrophobic POPs such as bisphenol A (BPA) and atrazine (ATZ) were mainly degraded in gas-liquid interface indicated by the low synergistic values correlation compared to SMX [i.e., SMX has a higher synergistic factor, fsyn (3.26) than BPA (1.30) and ATZ (1.35)]. Also, fsyn was found linearly correlated with the contribution factor of photocatalysis to split H2O2. Three times of consecutive kinetics using an effluent of municipal (MP) wastewater spiked by POPs presented >98% POPs and >96% total organic carbon (TOC) removal.