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Bromide elevation in surface freshwater is unavoidable due to climate change and anthropogenic activities. Freshwater impaired by algal activity and bromide elevation has become problematic worldwi...

This study evaluated the level of the contaminant of the heavy metals in sludge from different sources and the ecological risk criteria associated with it was also analyzed to establish its reuse in agriculture. The sludge samples were collected from the water plant (WTP), wastewater treatment plant (WWTP), and industrial water treatment plant (IPT) in Taiwan. The inductively coupled plasma mass spectrometry was used to measure the trace metals in sludge. The pollution level and ecological risk criteria for heavy metals in sludge were also used to evaluate its reuse in agriculture. The result shows the average concentrations of trace metals in sludge for three groups (WTP, WWTP, and ITP). Significant correlations were found between concentrations of Zn-Ag (

Tap water contains some heavy metals and bio-organic substances with variety of concentration and these cannot be treated using regular physicochemical processes. So the present study, aims at evaluating the effectiveness of the sterilization using electrocatalytic technique with Escherichia coli (E. coli) as the observed index. The operational parameters such as anode material, voltage, inflow method, and electrode number are studied to understand the variation of pH, conductivity, E. coli, and residual chlorine of tap water. The outcome reveals that the maximum sterilization efficiency of E. coli is obtained using the titanium dioxide electrode, followed by ruthenium dioxide and graphite. A disinfection efficiency of 98% can be easily achieved. Also, the appropriate increase in the operating voltage can increase the sterilization efficiency and decrease the treatment time. The sterilization efficiency of the E. coli can reach 100% under the continuous inflow of tap water and the voltage of 60 V for 1 min, which meets the conventional standard of drinking water (6 CFU/100ml). The estimated operating cost of treatment of 1 ton of tap water is NTD 1.7.

In this study, the preparation procedures for the polysulfone (PSf) substrate and polyamide (PA) selective layers were systematically investigated to determine their effects on the separation performance of thin-film composite (TFC) forward osmosis (FO) membranes in terms of the permeate flux (Jw) and reverse solute flux (Js). Furthermore, the PA active layer was modified by adding different proportions of an emerging material, graphene oxide (GO), to increase Jw and decrease Js. The experimental results indicated that special attention should be paid to the preparation of the PSf casting solution, which required thorough degassing, sealing, and humidity and temperature control. The optimum casting height was discovered to be 175 μm. For PA layer formation, the same amount of polymer solutions (resulting thickness of 78.5 μm) on the top surface of the PSf substrate (on the side facing the water during phase inversion) resulted in the highest FO performance. GO modification of the PA layer at the dosage of 0.0175 wt% considerably enhanced Jw to 14 L m−2 h−1 and reduced Js to 0.23 mol m−2 h−1. However, higher GO dosage (0.02 wt%) led to lower membrane performance due to aggregation of GO nanoparticles, as confirmed using scanning electron microscopy. Next, the prepared membranes were applied to dye rejection and sludge concentration for water recovery. The virgin and modified FO membranes both exhibited high rejection efficiency (≥96.0 %) for dyes commonly used in the textile industry. The 0.0175 %-GO-modified FO membrane exhibited a higher concentration factor (1.67) and greater water recovery (40.0 %) than the virgin membrane (1.45 and 31.2 %, respectively). Therefore, the application of FO for water recovery is economic and environmentally friendly in terms of saving the transportation cost of sludge disposal while recovering water for reuse in wastewater treatment plants.

Nanocomposite materials can enhance the capabilities of water treatment processes such as photocatalysis. In this work, novel light-driven nanocatalysts were synthesized by using nickel ferrite (NiFe2O4) to nanoenable graphene oxide (GO) substrates. GO is an emerging 2D nanomaterial with high conductivity and adsorption properties. Moreover, the electric properties of GO improve photocatalytic performance by promoting charge carrier separation. Results of the characterization of the nickel ferrite nanoenabled graphene oxide (NiFe2O4@GO) nanocomposites demonstrate that homogeneous and stable photocatalysts were produced. The as-synthesized nanocatalysts enabled complete decolorization of the colored water matrix in short irradiation times of 150 min using minimal catalyst loading at 0.5 g L−1. The selective hook and destroy mechanism reduced the competitive effect of co-existing ions in solution. Furthermore, the use of specific scavengers helped to elucidate the degradation mechanisms of organic dye methylene blue by NiFe2O4@GO nanocomposites.

This study proposed a method for analysis of 10 phthalate esters compounds from wastewater treatment plant sludges. The analytical efficiency of GC-MS for of target compounds was verified by a standard mixture of phthalate esters. The response factors related to the respective internal standards from a five-point calibration curve quantified the phthalate esters in individual compounds. Based on the literature compiled by environmental agencies, new generation phthalate compounds have been developed, such as di-iso-nonyl phthalate (DiNP), di-iso-decyl phthalate (DiDP), as alternative to conventional phthalates. The analytical results showed that the total PAEs concentration was in the range from 7.4 to 138.6 mg kg

In this study, Fenton oxidation and activated persulfate oxidation were used to investigate the optimized in situ chemical oxidation (ISCO) process for its efficiency on petroleum-hydrocarbon contaminated groundwater cleanup. In the batch and column experiments using benzene and toluene as the target compounds, oxidant depletion, soil oxidant demand (SOD), adsorption of oxidant on soils, and oxidation kinetics were studied. Results show that Fenton oxidation process was more catalytic than activated persulfate oxidation by ferrous iron catalysis. Higher SOD value was obtained for H2O2 than persulfate because H2O2 had higher reactivity to soil organic matter. In addition, increased benzene and toluene oxidation rates were observed with increased concentrations of H2O2 and persulfate oxidants. The calculated pseudo first-order decay rate constants (k’) for Fenton and activated persulfate oxidation processes were 1.65 and 0.13 1/h for benzene and 1.28 and 0.1 1/h for toluene, respectively. Compared to persulfate oxidation, results indicate that Fenton oxidation had much higher reaction rates on petroleum hydrocarbon oxidation. Results from the column experiment show that up to 5.94 pore volumes (PVs) of H2O2 solution and 12.85 PVs of persulfate solution were required to cleanup benzene and toluene contaminated groundwater with an oxidant concentration of 10 wt%, ferrous iron concentration of 100 mg/L, and initial contaminant concentration of 50 mg/L. Results indicate that the Fenton oxidation process would be a more practical and efficient approach to remediate petroleum-hydrocarbon contaminated groundwater. The results would be useful in developing an ISCO system for a practical field application to cleanup benzene and toluene contaminated groundwater.

This paper describes the fabrication, modification, and evaluation of the performance of thin-film composite (TFC) forward osmosis (FO) membranes for lab-scale aquaculture wastewater recovery using various fumed silica (SiO2) nanoparticles. The active polyamide (PA) layers of these membranes were novelly modified using different types of pretreated SiO2 nanoparticles [virgin SiO2, dried SiO2, and 3-aminopropyltriethoxysilane (APTES)-modified SiO2] and concentrations (0.05, 0,1, 0,2, and 0.4 wt%) to improve the membrane hydrophilicity with minimum particle agglomeration. Results show that the APTES-SiO2 modified membrane had the highest water flux and selectivity, followed by the dried-SiO2 modified membrane. The APTES coupling agent notably reduced the SiO2 aggregation on the membrane surface and improved membrane hydrophilicity. Consequently, high permeate flux and an acceptable reverse solute flux were observed. The optimal SiO2 concentration for PA modification was 0.1 wt% for all the nanoparticle types. The virgin and APTES-SiO2 modified membranes were used for aquaculture wastewater recovery. The water recovery rate reached 47% in 84 h when using the APTES-SiO2 modified membrane, while it reached only 26% in 108 h when using the virgin membrane. With a suitable design of the filtration apparatus and choice of draw solution (DS), the prepared novel TFC-FO membrane containing APTES-modified SiO2 can be used for recycling aquaculture wastewater into the DS, which can then be reused for other purposes.

Methylmercury (MeHg) presents high toxicity to humans and can be accumulated to organisms via the food chains. In aquatic environments, MeHg is mainly formed by microorganism using the bioavailable inorganic mercury in sediment. In this study, a total of 120 surface sediments from 20 sites in the Kaohsiung Harbor were collected quarterly in the period from July 2016 to October 2017 and analyzed for total mercury (THg), bioavailable inorganic mercury (BIHg), MeHg, and several geochemical parameters. The concentrations of THg, BIHg, and MeHg in sediment were 455-5108, 7.0-1021, and 0.84-24.1 μg/kg dw, respectively. Results indicated that the percentage of MeHg to THg (MeHg ratio) in most sediment (85%) is1.2%. Correlation analysis showed that MeHg in sediment was mainly controlled by BIHg (r = 0.759, p 0.01), while the concentration of BIHg in sediment was mainly related to TOC (r = 0. 480, p 0.01) and THg (r = 0.435, p 0.01). The relationship between total bioavailable inorganic mercury (containing BIHg and the bioavailable inorganic mercury used in the synthesis of MeHg) and MeHg concentration in the sediments that collected from the estuary, harbor channel, and the entrance was established by a Michaelis-Menten model to predict the maximum value of MeHg. The efficiency of Hg methylation in the sediments of Kaohsiung Harbor is significantly affected by the total bioavailable inorganic mercury and the related environmental factors. In addition, changes in environmental conditions caused by local seasonality should also be an important factor to consider when assessing the efficiency of Hg methylation.

The main objective of this study was to evaluate the effect of different pyrolysis temperatures on the formation of polycyclic aromatic hydrocarbons (PAHs) in biochar originated spent coffee ground (SCG) and the tetracycline (TC) adsorption behavior of biochar in water. The results showed that biochar synthesized at 500 °C (SCG 500) contained low PAHs (600 µg kg−1) and the highest TC adsorption efficiency. In addition, the characteristics, influencing factors on TC adsorption, and the related mechanisms of SCG 500 were comprehensively investigated. The results showed that the highest efficiency was observed at pH of 7 and the presence of ions in salinity solution reduced the adsorption capacity of SCG 500. The electrostatic interaction, hydrogen bonding, and π-EDA were the major adsorption mechanisms. Safety PAHs level, low-cost, widely material sources and high TC removal capacity suggested that SCG 500 was a promising environmentally friendly effective absorbent.

An electrode made of loofah sponge derived activated carbon supported on nickel foam (AC/Ni) was successfully fabricated and used to remove ammonium ion (NH4+) from aqueous solution. A multilayer adsorption isotherm was used to describe ammonium electro-sorption on AC/Ni electrodes at different temperature, initial NH4+ concentration, and electrical field. The cyclic voltammetry (CV) results suggested that the electrical capacitance of AC/Ni electrodes, with the AC being prepared without preheating (OAC) or with low temperature heating (i.e., 300 AC), were higher than those prepared at high preheating temperature (i.e., 400 AC and 500 AC). Increasing the electro-sorption temperature from 10 to 50 °C decreased the monolayer NH4+ adsorption capacity from 5 to ca. 2–3 mg-N g−1, respectively. Background electrolyte, namely, sodium sulfate, exhibited significant competitive effect on the adsorption of ammonium ion at sodium ion concentration > 10−2 M. The activation energy and heat of adsorption were 9–23.2 kJ mol−1 and −3.7–−10.7 kJ mol−1, respectively, indicating a physisorption and exothermic adsorption characteristics. Based on the kinetics and thermodynamics analysis, there was slight increase in the activation energy with elevating preheating temperature, which increased the quantity of micro-pores and surface heterogeneity of the AC materials. Overall, results clearly demonstrated that carbon pyrolysis played a role on the capacitive charging behaviors of electrodes and the efficiency of NH4+ electro-sorption on the AC/Ni electrodes.

A simple and facile synthesis method is developed for the fabrication of CoO loaded ordered mesoporous carbon nitride (CoO@meso-CN) composites, at various CoO loadings, and used, for the first time, to activate persulfate (PS) for methylene blue (MB) degradation. The interfacial interaction between the ultrafine CoO nanoparticles, immobilized by high surface area, regular mesopores, and graphitic nature of the meso-CN support can further enhance the catalytic activation of PS for methylene blue (MB) degradation. Among all catalysts studied, the 5-wt% CoO@meso-CN exhibits the best catalytic performance with a kobs of 0.264 min−1. High initial pH, especially at pH-11, is more beneficial for PS activation. Furthermore, the CoO@meso-CN nanocatalyst is highly stable with a consistently high degree of MB degradation and negligible cobalt leaching for at least 5 consecutive catalytic cycles. Both SO4 − and OH are the major reactive species based on results of EPR and quenching experiments. The degradation intermediates of MB are also identified by HPLC/MS/MS and the possible degradation pathway is proposed. Results clearly demonstrate that CoO@meso-CN is a promising green catalyst with enormous potential for the remediation of hazardous chemicals using PS.

In this study, an environmentally friendly and economically viable bamboo biochar (BB) was modified by Fe3O4 and was applied for the treatment of real river sediments containing the endocrine disruptor chemical (EDC) 4-nonylphenol (4-NP). The microporosity of Fe3O4–BB was clearly observed from the N2 adsorption isotherms. The catalytic performance of Fe3O4–BB is highly dependent on pH and the catalyst dosage. The degradation efficiency of 4-NP (85%) was achieved at pH 3.0 using an initial dosage of 3.33 g L−1 Fe3O4–BB and 2.3 × 10−5 M persulfate (PS) in a biochar–sediment system. The kinetic behavior of 4-NP degradation with catalysis can be accounted by using the Langmuir-Hinshelwood type kinetic model. The MTT assay results indicated that Fe3O4–BB has a low potent cytotoxic effect and is therefore suitable for application in remediation of contaminated sediment.

The purpose of this study was to evaluate the feasibility of lightweight aggregate (LWA) made from dredged harbor sediment and basic oxygen furnace (BOF) slag to increase their reutilization. The effects of preheating, sintering and raw materials proportion on the properties of LWA were discussed in term of particle density, water absorption, and compressive strength. Microscopic structure, water-soluble chloride and heavy metals leachability of the LWA were also examined. Results showed that the mixture of the dredged harbor sediment and BOF slag under the manufacturing process with preheating temperature at 500 °C for 10 min and sintering temperature at 1175 °C for 15 min was conducive to be a low water absorption and high strength LWA, which had as low as 1.73 g cm−3 and 3.45% for dry particle density and water absorption respectively. Its compressive strength reached 23.2 MPa when the addition of BOF slag was up to 27%. The LWA prepared in this study also have very low water-soluble chloride and heavy metals leachability, all compliant with Taiwan regulatory standards, thus would be suitable for further civil engineering application. The results of this study provide useful information on co-treating of wastes and recycled resources as LWA.

The advanced oxidation process (AOP) is a promising remediation technology for persistent organic pollutants in the environment. We herein investigated the ability of a magnetic carbon microsphere (CM)-based composite catalyst (Fe3O4−CM) to catalyze sodium persulfate (Na2S2O8, SPS) for the remediation of marine sediments contaminated with polycyclic aromatic hydrocarbons (PAHs). The effectiveness of the process parameters, catalyst dose, and initial pH were investigated. Using the optimized conditions, 87% of the PAHs were removed in the Fe3O4−CM/PS system within 24 h, compared with 59% and 41% in the case of persulfate (PS) and CM/PS (PS concentration = 1.3 × 10−5 M, catalyst concentration = 5.0 g/L, pH = 6.0) alone. The PAH reduction rate can be attributed to the uniform graphitic structure of Fe3O4−CM, which serves as an effective matrix for PAH degradation by providing additional active sites. The degradation of the PAHs was related to the number of rings in their structure, as confirmed by the higher degradation efficiency observed for high aromatic ring PAHs (HPAHs). Thus, we herein demonstrated the CM-mediated electron transfer catalysis of the surface functional groups at circumneutral pH values in the Fe3O4−CM/PS system to the highly efficient removal of PAHs from contaminated sediments.

Some industrial wastewater containing complicated contents (e.g., heavy metals and organics) and extensive concentration-variation cannot be well-treated by physical-chemical treatment processes. In order to obtain the feasible electrochemical technique, an electrocatalytic-membrane process (ECMP) was established to treat such wastewater from a mint factory in Taiwan. Wastewater samples with pollutants of Cu2+, Ni2+ and chemical oxygen demand (COD) were categorized into three types based on pH and concentrations. The complexity of wastewater is attributed that a verity of chemical reagents and manufacturing methods are employed to produce different kind of coins. In this study, each type of wastewater was treated by the ECMP and integrated with other techniques to find out the appropriate procedures. Results indicate that the sole ECMP can effectively remove the Cu2+, Ni2+, and COD when the wastewater is with relatively low pH (around 3–5), low COD (around 50 mg L−1), and high concentration of heavy metals (Cu2+ concentration over 500 mg L−1). However, the ECMP should combine with pH-adjustment to effectively remove the Cu2+, Ni2+, and COD when the wastewater is with very low pH (close to 1), high COD (over 200 mg L−1), and high concentration of heavy metals. In addition, the ECMP has to link the electrocoagulation (ECG) to decrease the Cu2+, Ni2+, and COD concentration when the wastewater is with neutral pH (around 7), middle-level COD (around 130 mg L−1), and low concentration of heavy metals (Cu2+ concentration around 1.0 mg L−1). Accordingly, the ECMP integrated with other treatment processes gains potential to treat refractory wastewater.

A sustainable system capable of simultaneous removal of organic contaminants and hydrogen generation in wastewater treatment operation was studied using hematite electrode in the presence of Mn(II), PEC-Mn(II), as a proof of concept. The photoelectrochemical (PEC) system exhibited methylene blue (MB) decolorization threefold faster than that of photo-Fenton processes and yielded comparable photocurrent density to relative to the control system, i.e., PEC water splitting in the absence of MB at otherwise identical operation conditions. Furthermore, the advantages of PEC-Mn(II) system were no H2O2 addition, hydrogen production potential, and ease in Mn(II) separation via the formation of MnO2 precipitates during wastewater treatment operations. The PEC-Mn(II) process is a promising and sustainable approach toward wastewater treatment with the capability of concurrent photochemical energy generation. Moreover, the PEC-Mn(II) process can be an emerging energy-from-wastewater alternative in addition to other systems such as microbial fuel cell and anaerobic digestion.

Harbor sediments normally accumulate the pollutants from municipal and industrial activities in the estuarine zone. This work aimed to characterize the fractionation change of heavy metals in harbor sediments before and after chemical washing. Since the annual dredging around the Kaohsiung Harbor has increased over time, the influence of ex-situ acid washing on sediment quality needs to be evaluated. Experimental parameters of acid washing included the solid loading (4–20%) and types (HCl, HNO3, and citric acid) and concentrations (0.01–1 M) of acids. The fractionation of Cu, Zn, Ni, Cd, Cr, and Pb in the sediments at three estuaries, the Chienchen River, Canon River (Dock No.5), and Yanshui River, before and after washing processes were determined through sequential extraction. The washing efficiencies of HCl, HNO3, and citric acid were similar, being 80.1–83.7%, 27.6–30.9%, 20.7–23.9%, and 97.2–98.8% for Zn, Ni, Cr, and Cd, respectively. After 15 min of washing, HCl was found as a suitable washing agent, and particularly, more effective for Cu (65.3%) and Pb (79.4%) than other acids. The extraction process suggested that the acid washing of carbonate, the Fe-Mn oxide composite, and organic phases were highly correlated to their quantities in the sediments. However, the removal efficiency was inversely related to the metals in the residual phase. Knowing the mobility and bioavailability of heavy metals based on fractionation of metals benefits the assessment of the potential risk of dredged harbor sediment after the washing procedure. This study provided evidence that acid washing, as a remediation method, could be versatile in removing heavy metals from mobile phases without causing mineralogical changes to the contaminated sediments of the harbor area.

Some agricultural lands have been contaminated by heavy metals in Taiwan for several decades, because the irrigation system was polluted by wastewater. In this study, a circulation-enhanced electrokinetics (CEEK) and phytoremediation were applied alternately to the real lead-contaminated site. In the beginning, the CEEK was used; then, the corn plants were raised. After this phytoremediation, the CEEK was employed again. Experimental results show that the lead concentration can be reduced from 5672 mg/kg to 2083 mg/kg (around 63%) after the three-stage treatment (CEEK + corn + CEEK). At each stage, CEEK, corn plants, and CEEK can remove around 25%, 5%, and 30% lead from the soil, respectively. During the whole process, the soil pH can maintain around neutral range and the electrical conductivity of soil was stable. The electricity consumption of the CEEK was quite low (89 USD per ton) and the corn plants still were alive throughout the remediation.

To evaluate the toxicity of sediments collected from the mouths of four rivers and entrances of Kaohsiung Harbor, Taiwan, a combination of in vitro cytotoxicity assays (Clone 9 cells) and chemical analysis that quantified 16 polycyclic aromatic hydrocarbons (PAHs), 10 phthalate esters (PAEs), and 2 alkylphenols (APs) was employed. Results showed that the total concentrations of PAHs, PAEs, and APs ranged between 77.9 and 24,363 ng/g dw, between 268 and 118,010 ng/g dw, and between 32.6 and 84,438 ng/g dw in sediments, respectively. The highest concentrations of PAHs, PAEs, and APs were found in the mouths of the Salt River (SR), Love River (LR), and Jen-Gen River (JR), respectively. Mean reference sediment quotient (m-RSQ) values were calculated using the chemical concentrations measured in the sediment of entrance I (EI) as the benchmark, and the order was SR > LR > JR > CR (Canon River mouth) > EII (entrance II) > EI. Results of the cytotoxicity assay showed that the 50% inhibitory concentration (IC50) of Clone 9 cells was in the order of LR < SR < JR < CR < EII < EI. Results on DNA content, apoptotic and autophagy protein biomarkers, and acridine orange staining indicated that the cause of death of Clone 9 cells after treatment with sediment extracts of the LR site was mainly through apoptosis. There was a significant correlation between m-RSQ values and IC50 of Clone 9 cells. The correlation analysis between cytotoxicity and chemical analytical data indicated that certain unknown chemicals may exist in LR sediment. Overall, this study demonstrated that the combination of chemical and biological analyses can provide a more comprehensive and realistic assessment of sediment toxicity to aquatic organisms compared to traditional chemistry-based-only analytical approaches.

Bi2WO6 (BW) and SnO2/Bi2WO6 composites (SnBWs) were synthesized by a single-step solvothermal process. Four SnO2/BW molar ratios, 0.1, 0.25, 0.5 and 1 were used to generate 0.1SnBW, 0.25SnBW, 0.5SnBW and 1SnBW. The surface characteristics of BW, SnO2 and SnBWs were elucidated by X-ray diffractometry (XRD), transmission electron microscopy, specific surface area analysis, UV–vis spectrophotometry, photoluminescence spectrophotometry and X-ray photoelectron spectroscopy. C.I. Reactive Red 2 (RR2) was used as a target pollutant to compare the photocatalytic activities of the prepared SnBWs. The effects of RR2 concentration and photocatalyst dosage on RR2 photodegradation were elucidated. The XRD results revealed that all of the peaks of SnBWs in XRD patterns could be assigned to SnO2 or BW, and no other peak was found, indicating that SnO2 and BW were successfully composited. The band gaps of SnO2, BW, 0.1SnBW, 0.25SnBW, 0.5SnBW and 1SnBW were estimated to be 3.75, 2.85, 2.95, 2.94, 2.93 and 2.97 eV, which correspond to RR2 photodegradation rates under simulated solar light irradiation of 0.0025, 0.0255, 0.0333, 0.0279, 0.0408 and 0.0174 min−1. 0.5SnBW had the highest photocatalytic activity in RR2 photodegradation. The RR2 photodegradation rate increased as the 0.5SnBW dose increased, but decreased as the RR2 concentration increased. The results of adding scavengers suggested that the photogenerated holes were the main oxidative species in RR2 photodegradation in the 0.5SnBW system. The findings of this study suggest that the effective suppression of the recombination of electron–hole pairs in 0.5SnBW may improve the photocatalytic activity of 0.5SnBW over those of pure BW and SnO2.

Despite the growing potential in various applications of nanobiochars, there are still concerns regarding their health effects. In this study, we used a normal human in vitro model to investigate the possible toxic effects, including pulmonary toxicity, of epithelial exposure to nanobiochars. Nano-tobacco stem-pyrolyzed biochars (nTSBs), which are generated at 500 °C, were used to analyze their potential adverse effects on the lungs. Our results demonstrated that nTSBs can cause evident cytotoxic and genotoxic effects in epithelial cells by inducing ROS formation. nTSB exposure also led to the activation of inflammatory factors. Furthermore, decreases in transepithelial electrical resistance and zonula occludens proteins after exposure to nTSBs impaired the integrity of the epithelial barrier. Increases in oxidized α1-antitrypsin in BEAS-2B cells also suggested that nTSB exposure increases the risk of chronic obstructive pulmonary disease. However, all of these adverse responses were induced by high concentrations of nTSBs. Accordingly, the pulmonary toxic potential of nTSBs occurring at high concentrations is likely not the same as that occurring at more realistic outdoor exposure concentrations. Collectively, our results indicate that the risk of nTSB toxicity is low when nTSBs are used as raw materials in commercial applications.

Managing the concentration of atmospheric CO2 requires a multifaceted engineering strategy, which remains a highly challenging task. Reducing atmospheric CO2 (CO2R) by converting it to value-added chemicals in a carbon neutral footprint manner must be the ultimate goal. The latest progress in CO2R through either abiotic (artificial catalysts) or biotic (natural enzymes) processes is reviewed herein. Abiotic CO2R can be conducted in the aqueous phase that usually leads to the formation of a mixture of CO, formic acid, and hydrogen. By contrast, a wide spectrum of hydrocarbon species is often observed by abiotic CO2R in the gaseous phase. On the other hand, biotic CO2R is often conducted in the aqueous phase and a wide spectrum of value-added chemicals are obtained. Key to the success of the abiotic process is understanding the surface chemistry of catalysts, which significantly governs the reactivity and selectivity of CO2R. However, in biotic CO2R, operation conditions and reactor design are crucial to reaching a neutral carbon footprint. Future research needs to look toward neutral or even negative carbon footprint CO2R processes. Having a deep insight into the scientific and technological aspect of both abiotic and biotic CO2R would advance in designing efficient catalysts and microalgae farming systems. Integrating the abiotic and biotic CO2R such as microbial fuel cells further diversifies the spectrum of CO2R.

A sensitive voltammetric sensor has been developed for hazardous methyl parathion detection (MP) using graphene oxide@Ce-doped TiO2 nanoparticle (GO@Ce-doped TiO2 NP) electrocatalyst. The GO@Ce-doped TiO2 NPs were prepared through the sol-gel method and characterized by various physicochemical and electrochemical techniques. The GO@Ce-doped TiO2 NP–modified glassy carbon electrode (GCE) addresses excellent electrocatalytic activity towards MP detection for environmental safety and protection. The developed strategy of GO@Ce-doped TiO2 NPs at GCE surfaces for MP detection achieved excellent sensitivity (2.359 μA μM−1 cm−2) and a low detection limit (LOD) 0.0016 μM with a wide linear range (0.002 to 48.327 μM). Moreover, the fabricated sensor shows high selectivity and long-term stability towards MP detection; this significant electrode further paves the way for real-time monitoring of environmental quantitative samples with satisfying recoveries.

Freshwater demand is rising worldwide due to largely increasing population and industrialization. Latest focus is to explore the Ocean and saline effluent from industries to produce freshwater in a sustainable way via algal desalination. Current physicochemical desalination technology is not only an energy-intensive and expensive process but also gives severe environmental impact from brine and GHGs emissions. Therefore, it is neither environmentally-friendly nor feasible to countries with limited resources. Biodesalination could be an attractive technology with recent breakthroughs in algal bioprocess with fast growth rate under highly saline conditions to effectively remove salts optimally 50–67% from saline water. Algal desalination mainly occurs through biosorption and bioaccumulation which governs by biotic and abiotic factors e.g., strain, temperature, pH, light and nutrients etc. This review provides a current scenario of this novel technology by an in-depth assessment of technological advancement, social impact, possible risks and scope for policy implications.

Biochar is a carbon-rich material prepared from the pyrolysis of biomass under various conditions. Recently, biochar drew great attention due to its promising potential in climate change mitigation, soil amendment, and environmental control. Obviously, biochar can be a beneficial soil amendment in several ways including preventing nutrients loss due to leaching, increasing N and P mineralization, and enabling the microbial mediation of N2O and CO2 emissions. However, there are also conflicting reports on biochar effects, such as water logging and weathering induced change of surface properties that ultimately affects microbial growth and soil fertility. Despite the voluminous reports on soil and biochar properties, few studies have systematically addressed the effects of biochar on the sequestration of carbon, nitrogen, and phosphorus in soils. Information on microbially-mediated transformation of carbon (C), nitrogen (N), and phosphorus (P) species in the soil environment remains relatively uncertain. A systematic documentation of how biochar influences the fate and transport of carbon, phosphorus, and nitrogen in soil is crucial to promoting biochar applications toward environmental sustainability. This report first provides an overview on the adsorption of carbon, phosphorus, and nitrogen species on biochar, particularly in soil systems. Then, the biochar-mediated transformation of organic species, and the transport of carbon, nitrogen, and phosphorus in soil systems are discussed. This review also reports on the weathering process of biochar and implications in the soil environment. Lastly, the current knowledge gaps and priority research directions for the biochar-amended systems in the future are assessed. This review focuses on literatures published in the past decade (2009–2021) on the adsorption, degradation, transport, weathering, and transformation of C, N, and P species in soil systems with respect to biochar applications.

Lytic polysaccharide monooxygenases (LPMOs) emerged a decade ago and have been described as biomass deconstruction boosters as they play an extremely important role in unravelling the enzymatic biomass hydrolysis scheme. These are oxidative enzymes requiring partners to donate electrons during catalytic action on cellulose backbone. Commercial cellulase preparations are mostly from the robust fungal sources, hence LPMOs from fungi (AA9) have been discussed. Characterisation of LPMOs suffers due to multiple complications which has been discussed and challenges in detection of LPMOs in secretomes has also been highlighted. This review focuses on the significance of LPMOs on biomass hydrolysis due to which it has become a key component of cellulolytic cocktail available commercially for biomass deconstruction and its routine analysis challenge has also been discussed. It has also outlined a few key points that help in expressing catalytic active recombinant AA9 LPMOs.

The presence of ultrafine plastics particles and its potential to concentrate and transport organic contaminants in aquatic environments have become a major concern in recent years. Specifically, the uptake of hazardous chemicals by plastics particles may affect the distribution and bioavailability of the chemicals. In this study, the adsorption of tetracycline (TC), an antibiotic frequently found in aquatic environments, on high-density polyethylene (PE) particles with the average size of 45 μm, was investigated. The PE particles were characterized for surface acidity for the first time. Results showed that pH controls the surface charge of PE particles. TC adsorption onto PE particles was rapid as expected following the pseudo-second-order rate law (r2 > 0.99). Polar forces in addition to specific chemical interactions, such as hydrogen bonding and hydrophophilicity controlled TC adsorption onto PE particles. Parameters, including pH, dissolved organic matter, ionic strength, major cations and anions affected TC adsorption onto PE micro-particles. Results indicated that PE particles can function as a carrier of antibiotics in the aquatic environment, which potentially imposes ecosystem and human health risks.

There has been growing research interest in exploiting biochar for cost-effective. removal of different pollutants. Heavy metals, especially copper II (Cu II) is highly toxic and nonbiodegradable pollutants, and has been major source of environmental pollution. In this study adsorption of Cu (II) on seaweed (Ascophyllum nodosum)-derived biochar was systematically examined. The removal efficiency based on surface property of biochar and type of interactions associated with biochar produced at varying pyrolysis conditions were investigated. The highest removal efficiency of Cu (II) from aqueous media was >99% with 223 mg g−1 Cu (II) adsorption capacity observed by biochar derived at 700 °C and pH 5. Langmuir adsorption isotherm described the adsorption mechanisms of Cu (II) on biochar with cationic and anionic electrostatic attractions, surface precipitation, and pore depositions. Thus, this study shows that waste biomass (seaweed) could be a valuable bioresource for heavy metal remediation from various water bodies.

Recently, microalgal biomass has become an attractive and sustainable feedstock for renewable production of various biochemicals and biofuels. However, attaining required productivity remains a key challenge to develop industrial applications. Fortunately, mixotrophic cultivation strategy (MCS) is leading to higher productivity due to the metabolic ability of some microalgal strain to utilise both photosynthesis and organic carbon compared to phototrophic or heterotrophic processes. The potential of MCS is being explored by researchers for maximized biochemicals and biofuels production however it requires further development yet to reach commercialization stage. In this review, recent developments in the MCS bioprocess for selective value-added (carotenoids) products have been reviewed; synergistic mechanism of carbon and energy was conferred. Moreover, the metabolic regulation of microalgae under MCS for utilized carbon forms and carbon recycling was demonstrated; Additionally, the opportunities and challenges of large-scale MCS have been discussed.

This study aims to clarify the removal mechanism and to calculate the effective current of electrocoagulation (i.e., EC) for treating wastewater containing Ni(II), Cu(II), and Cr(VI). The adsorption behavior of various heavy metals onto Al(OH)3 coagulant generated by the EC process was investigated and the estimating method of the corresponding current was established. Results indicate that adsorption of single Ni(II) and Cu(II) by Al(OH)3 coagulant can be simulated by the Langmuir isotherm, while Cr(VI) adsorption fits the Freundlich isotherm better. As treating single heavy metal of wastewater, the removal mechanism of the EC process is the adsorption reaction. Under the coexisting condition, the Ni(II) and Cu(II) will compete for the same active sites on the Al(OH)3 surface and Cu(II) suppresses Ni(II) adsorption. As treating the coexisting heavy metals, Ni(II) removal not only associates with adsorption but also with the coprecipitation. In contrast, Cr(VI) does not compete with other metal ions for the same type of adsorption sites. Whether single or coexisting conditions, the adsorption capacity of heavy metals onto Al(OH)3 coagulants can be used to compute the necessary current to effectively remove heavy metals in the EC system.

Heterogeneous Fenton-like catalyst prepared by dispersing iron oxides in activated carbon (FeOx@AC) has frequently been assembled for advanced oxidation processes (AOPs). An intriguing but barely emphasized property of FeOx@AC is that it can be easily reactivated through a simple carbothermal reaction. Importantly, by this manner the life time of FeOx@AC could be effectively enhanced. We herein reported the synthesis of FeOx@ACs hydrothermally with assistance of several commercially available surfactants and their performance in degrading real dye wastewater were evaluated. In general, as-synthesized FeOx@ACs were noted to equip high Fe content. Deposited FeOx reduced the fraction of micropores but simultaneously introduced additional mesopores and macropores. Elevated magnetite content was observed in FeOx@AC equipped with high fraction of micropore and mesopore and macropore but fast dye degradation occurred at FeOx@AC possessing low fraction of micropore along with low mesopores and macropores. Reactivation via carbothermal reaction redistributed the deposited FeOx by increasing micropores while decreasing mesopores and macropores. Importantly, well dispersed FeOx synthesized with the assistance of surfactants exhibited high resistance to the corrosion in the degradation process. For the perspective of circular economy, deep understanding the material chemistry of FeOx@AC would be of particularly interest for further enhancing its life time.

A series of experiments with different NaCl concentrations added to the PCB (printed circuit board) wastewater were prepared to investigate the chloride effect on the formation of aluminum floc and removal efficiency of Cu and Ni. The effects of pH, current density, and different concentration of NaCl were studied and the results are discussed. Results imply that chloride ions are favored to avoid the passivation of the aluminum anode in the EC (electro-coagulation) system. Chloride ions used as the electrolyte can facilitate the release of Al3+, which results in the current efficiency of over 100% in the EC system. For the PCB factory&rsquo, s wastewater, the EC system could remove Cu2+ and Ni2+ effectively (both Cu and Ni concentration of treated wastewater was less than 1.0 mg/L within three minutes). PCB wastewater&rsquo, s pH value could maintain stably about 9.0 in the EC system when the initial pH value was around 2.5. The estimated electricity consumption for treating PCB wastewater by the EC process was about 0.894 kWh for each meter of cubic wastewater.

Dyes are hazardous compounds commonly found in industrial wastewaters. Efficient and inexpensive removal of dye molecules from the water matrix has been demonstrated by adsorption processes. Magnetic nano-adsorbents, such as metal ferrites, can be efficiently recovered from the reaction mixture after treating the pollutant. Herein, MFe2O4@GO (M = Cu, Co or Ni) was synthesized via solution combustion method for the removal of dye molecules from aqueous solutions. The characteristics of the MFe2O4@GO, including surface area and pore diameter, surface functional groups, and elemental composition, were examined. Methylene blue was used as representative dye pollutant. Batch adsorption results conformed to the Langmuir isotherm. Maximum adsorption capacities of the MFe2O4@GO (M = Cu, Co or Ni) were 25.81, 50.15 and 76.34 mg g−1, respectively. Kinetics of methylene blue adsorption fitted the pseudo-second-order model. Overall, NiFe2O4@GO exhibited the highest adsorbent performance among the graphene-metal ferrites investigated, primarily because of its high specific surface area and presence of mesopores.

A facile impregnation method was used to fabricate a hybrid CoO-3D ordered mesoporous carbon nitride (CoO@mpgCN) catalyst that effectively activated peroxymonosulfate (PMS) for the degradation of pharmaceutical chemical, exemplified by antibiotic sulfamethoxazole (SMX) in aqueous solutions. The CoO@mpgCN/PMS system exhibited high catalytic reactivity and SMX removal efficiency over a wide pH range with an observed rate constant (kobs) of 0.314 min−1. Furthermore, CoO@mpgCN was stable with consistently high degree of SMX degradation without having cobalt dissolution and loss of catalytic activity for at least five consecutive cycles. The significant catalysis performance of CoO@mpgCN was due to its uniformly distributed mesopores, large specific surface area, and high electron transfer ability at the active CoO sites. Both quenching experiments and electron paramagnetic resonance (EPR) analysis verified the yield, in abundance, of highly active species, specifically SO4 − and OH from the CoO@mpgCN activation of PMS, primarily. Hence, SMX degradation followed a radical chain reaction mechanism. The result of this study revealed a novel prospective of CoO@mpgCN composite as PMS activator for the remediation of recalcitrant pollutants in water.

Sludge from a groundwater treatment plant was used to prepare biochar by pyrolysis. The Fe–Mn rich biochar was used to activate percarbonate for the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated aquatic sediments. Results showed that the sludge–derived biochar (SBC) produced at a pyrolysis temperature of 700 °C was the most effective in activating percarbonate, which exhibited significant oxidative removal of PAHs. PAHs degradation took place via a Fenton-like oxidation manners, contributed from the Fe3+/Fe2+ and Mn3+/Mn2+ redox pairs, and achieved the highest degradation efficiency of 87% at pH0 6.0. Reactions between oxygenated functional groups of biochar and H2O2 generated of O2•– and HO• radicals in abundance under neutral and alkaline pH was responsible for the catalytic degradation of PAHs. Our results provided new insights into the environmental applications of SBC for the green sustainable remediation of organics-contaminated sediments and aided in reduction of associated environmental and health risk.

In this work, nano V/TiO2 catalysts at different molar ratios were prepared and fabricated as the electrocatalytic electrodes for electrocatalytic degradation. The effect of the vanadium doping on the surface morphology, microstructural, and specific surface area of V/TiO2 catalysts was probed by field emission scanning electron microscope (FESEM) x-ray diffractometer (XRD), and Brunauer&ndash, Emmett&ndash, Teller (BET), respectively. Afterward, the solution of Acid Red 27 (AR 27, one kind of azo dye) was treated by an electrocatalytic system in which the nano V/TiO2 electrode was employed as the anode and graphite as the cathode. Results demonstrate that AR 27 can be effectively degraded by the nano V/TiO2 electrodes, the highest removal efficiency of color and total organic carbon (TOC) reached 99% and 76%, respectively, under 0.10 VT (molar ratio of vanadium to titanium) condition. The nano V/TiO2 electrode with high specific surface area facilitated the electrocatalytic degradation. The current density of 25 mA cm&minus, 2 was found to be the optimum operation for this electrocatalytic system whereas the oxygen was increased with the current density. The electricity consumption of pure TiO2 and nano V/TiO2 electrode in this electrocatalytic system was around 0.11 kWh L&minus, 1 and 0.02 kWh L&minus, 1, respectively. This implies that the nano V/TiO2 electrode possesses both high degradation and energy saving features. Moreover, the nono V/TiO2 electrode shows its possible repeated utilization.

Contamination by microplastics (MPs) and the associated organic pollutants has caused potential threats to the ecological environment of global waters. In this study, MPs were sampled by trawling from the surface waters of the estuary, fishing port entrance and harbor entrance areas connected to the southwestern coast of Taiwan. Moreover, the abundance, morphological characteristics, composition, and associated polycyclic aromatic hydrocarbons (PAHs) of MPs were analyzed. The abundance of MPs was 0.36 ± 0.21 items/m3, which was 6.4 ± 10.7% of the abundance of zooplanktons. The average abundance of MPs was the highest in the estuary area, indicating that river transport was the primary way for MPs to enter the ocean. The most dominant MPs were small (0.33–2 mm; 78.8 ± 8.1%), colored (60.0 ± 12.8%), fragments (66.1 ± 10.6%), comprising PE (52.6 ± 7.6%), and PP (38.7 ± 9.4%). The decomposition of various plastic products and disposable plastic packaging may be the most significant source. The total concentration of PAHs in MPs ranged from 104 to 3595 ng/g dw, with an average of 818 ± 874 ng/g dw. The diagnostic ratios and the results of principal component analysis (PCA) and multiple linear regression of the absolute principal component scores (MLR-APCS) indicated that the PAHs were mainly contributed from sources related to petrogenic (71.4%) and vehicles (28.6%). Most likely due to MPs on the sea surface coming into contact with floating oil spills from ships or floating tar particles.

Shellfishes can easily accumulate metals via water and sediment and which may pose a human health risk by consumption. This study assessed the distribution of metals, including Cd, Cr, Cu, Pb, Ni, Zn, and Hg, in soft tissues of hard clam (Meretrix lusoria), surrounding water body, and sediment in the southwest coast of Taiwan. Hard clams contained the relatively higher concentration of the essential element, such as Zn, Cu, and Ni, and the metal concentration from high to low was Zn > Cu > Ni > Cd > Cr > Pb > Hg. However, the metal concentrations found in hard clam all were lower than the Sanitation Standard for Aquatic Animal of Taiwan. Results of bioaccumulation factors indicated that hard clam shows the ability of metal accumulation from water was higher than that from sediment. Moreover, the metal concentrations in hard clam were negatively correlated with body size except for Hg, which could be presented by the significant power function. Generally, hard clams from the aquaculture pond located on the southwest coast of Taiwan would not be harmful to adult consumers, except for people that consume shellfish more than 100 g. Besides strengthening the management of seafood safety and aquaculture, adjusting the eating and purchasing habits of the consumer could be a practical and feasible way for decreasing health risks. These results can assist the government in determining seafood safety and its implementation in Taiwan.

4-Nonylphenol (4-NP), a phenolic endocrine disruptor chemical (EDC), is known to have high toxicity to aquatic organisms and humans. The remediation of 4-NP-contaminated marine sediments was studied using red algae-based biochar (RAB) thermochemically synthesized from Agardhiella subulata with simple pyrolysis process under different temperatures of 300–900 °C in CO2 atmosphere. The RAB was characterized by XRD, Raman, FTIR spectroscopy, and zeta potential measurements. The calcium in RAB efficiently activated sodium percarbonate (SPC) to generate reactive radicals for the catalytic degradation of 4-NP at pH 9.0. The oxygen-containing functional groups reacted with H2O2, which increased the generation of reactive radicals under alkaline pH condition. Ca2+ ion was the active species responsible for 4-NP degradation. CaO/CaCO3 on RAB surface enhanced direct electron transfer, increased HO production, and 4-NP degradation in marine sediments. Langmuir‒Hinshelwood type kinetics well described the 4-NP degradation process. Remediation of contaminated sediments using RAB could be a sustainable approach toward closed-loop biomass cycling in the degradation of 4-NP contaminants.

Environmental impact of pesticides is one of the great concerns being addressed by water-food nexus research. Imidacloprid is one of the most used insecticides as an alternative for carcinogenic organochloride insecticides. Even though Imidacloprid has lower toxicity for mammals, its fate and incomplete degradation by conventional wastewater treatment technologies are worrisome when considering continuous environmental exposure. Application of fluidized-bed Fenton process is proposed as an alternative treatment to mitigate the impact of imidacloprid in water. The consequence of different experimental parameter variations such as Fe2+ catalyst concentration, H2O2 concentration and propylene glycol (a common excipient in commercial pesticides) was evaluated. Experimental results under optimized conditions demonstrate almost complete removal of imidacloprid and abatement of chemical oxygen demand and total organic carbon. The intermediates of oxidized imidacloprid yield during fluidized-bed Fenton treatment were identified using GC–MS and a reaction sequence for imidacloprid degradation was proposed. Keywords: Fluidized-bed Fenton, Wastewater treatment technologies, Contaminants of emerging concern, Advanced oxidation processes, Pesticides

The objectives of this study were to (1) conduct laboratory bench and column experiments to determine the oxidation kinetics and optimal operational parameters for trichloroethene (TCE)-contaminated groundwater remediation using potassium permanganate (KMnO4) as oxidant and (2) to conduct a pilot-scale study to assess the efficiency of TCE remediation by KMnO4 oxidation. The controlling factors in laboratory studies included soil oxidant demand (SOD), molar ratios of KMnO4 to TCE, KMnO4 decay rate, and molar ratios of Na2HPO4 to KMnO4 for manganese dioxide (MnO2) production control. Results show that a significant amount of KMnO4 was depleted when it was added in a soil/water system due to the existence of natural soil organic matters. The presence of natural organic material in soils can exert a significant oxidant demand thereby reducing the amount of KMnO4 available for the destruction of TCE as well as the overall oxidation rate of TCE. Supplement of higher concentrations of KMnO4 is required in the soil systems with high SOD values. Higher KMnO4 application resulted in more significant H+ and subsequent pH drop. The addition of Na2HPO4 could minimize the amount of produced MnO2 particles and prevent the clogging of soil pores, and TCE oxidation efficiency would not be affected by Na2HPO4. To obtain a complete TCE removal, the amount of KMnO4 used to oxidize TCE needs to be higher than the theoretical molar ratio of KMnO4 to TCE based on the stoichiometry equation. Relatively lower oxidation rates are obtained with lower initial TCE concentrations. The half-life of TCE decreased with increased KMnO4 concentrations. Results from the pilot-scale study indicate that a significant KMnO4 decay occurs after the injection due to the reaction of KMnO4 with soil organic matters, and thus, the amount of KMnO4, which could be transported from the injection point to the downgradient area, would be low. The effective influence zone of the KMnO4 oxidation was limited to the KMnO4 injection area (within a 3-m radius zone). Migration of KMnO4 to farther downgradient area was limited due to the reaction of KMnO4 to natural organic matters. To retain a higher TCE removal efficiency, continuous supplement of high concentrations of KMnO4 is required. The findings would be useful in designing an in situ field-scale ISCO system for TCE-contaminated groundwater remediation using KMnO4 as the oxidant.

Three transects were established along the southwestern coast of Taiwan; transects from north to south were respectively extended from the Kaohsiung Harbor, Kaoping River estuary, and Fangshan River estuary. Six metals including Pb, Cd, Cr, Cu, Zn, and Ni were analyzed in the zooplankton and seawater samples. A total of 24 groups of zooplankton were identified. Calanoid was the frequently collected group and accounted for greater than 40% of the relative abundance of zooplankton. Results showed that metal concentrations in seawater close to coast were higher than those in the outside of transect. The mean of metal concentrations in zooplankton followed the hierarchy: Zn > Cu > Pb > Ni > Cr > Cd. On the whole, metal concentrations in zooplankton from sampling sites in the coastal region were observed to be higher than those in the offshore region. The bioconcentration factor of zooplankton ranged within 103-105 for all studied metals and indicated that zooplankton in the seawater of southwestern Taiwan can accumulate metal even at background concentrations of metals. The value of diversity indices exhibited an increase in the distance to the coast, whereas the abundance showed no significant correlation with that. Consequently, the lowest mean abundance of zooplankton and the highest average metal bioaccumulation were found in transect outside Kaohsiung Harbor, representing that Kaohsiung Harbor has the contamination of anthropogenic metals that results in the impact on zooplankton.

The Love River and Ho-Jin River, two major urban rivers in Kaohsiung City, Taiwan, are moderately to heavily polluted because different types of improperly treated wastewaters are discharged into the rivers. In this study, sediment and river water samples were collected from two rivers to investigate the river water quality and accumulation of polycyclic aromatic hydrocarbons (PAHs) in sediments. The spatial distribution, composition, and source appointment of PAHs of the sediments were examined. The impacts of PAHs on ecological system were assessed using toxic equivalence quotient (TEQ) of potentially carcinogenic PAHs (TEQcarc) and sediment quality guidelines. The average PAHs concentrations ranged from 2161 ng/g in Love River sediment to 160 ng/g in Ho-Jin River sediment. This could be due to the fact that Love River Basin had much higher population density and pyrolytic activities. High-ring PAHs (4-6 rings) contributed to 59-90% of the total PAHs concentrations. Benzo(a)pyrene (BaP) had the highest toxic equivalence quotient (up to 188 ng TEQ/g). Moreover, the downstream sediments contained higher TEQ of total TPHs than midstream and upstream sediment samples. The PAHs were adsorbed onto the fine particles with high organic content. Results from diagnostic ratio analyses indicate that the PAHs in two urban river sediments might originate from oil/coal combustion, traffic-related emissions, and waste combustion (pyrogenic activities). Future pollution prevention and management should target the various industries, incinerators, and transportation emission in this region to reduce the PAHs pollution.

Kaohsiung Ocean Dredged Material Disposal Site (KODMDS) that located in the southwest offshore of Taiwan, has been annually disposed about 500,000 ton dredged sediments of Kaohsiung Harbor from 2003 to 2012. Five sediment cores collected from KODMDS and three from nearby reference sites were analyzed to evaluate their sedimentation rates, vertical profiles of heavy metal, and heavy metal pollution indices to assess the impact of dumping harbor dredged sediments into the ocean on the sediment quality in KODMDS. The sedimentation rate of 0.24 cm/y was estimated by the 210 Pb method, which means that the effected depth of the top layer of a core of D1 was affected in the period of dumping dredging sediments. The vertical distribution of heavy metals in the sediment cores from KODMDS showed the concentrations of most heavy metals were slightly elevated in the top layers of the sediment cores, which may be affected by the dumping of harbor dredged sediments. According to the analyzed results of the heavy metal pollution indices, the level of heavy metal pollution, the potential eco-toxicity and the potential ecological risk of the sediments in KODMDS exhibited only a slight increase, which indicated that the increase in concentration of heavy metals may potentially pose the insignificant impact on benthos inhabiting the disposal site.

Waste biomass of Lactobacillus brevis obtained from in vivo γ-aminobutyric acid (GABA) production was used for value-addition. This study aims to extract glutamate decarboxylase (GAD) and characterize it for in vitro GABA production. Extracted GAD showed an excellent activity for in vitro GABA production. 52 W ultrasonic output was best in crude GAD extraction which was purified by Q HP anion-exchange column followed by Superdex-200 colloid separation column. The molecular weight of the purified GAD was determined to be ~53 kDa, and the Km value for L-glutamic acid was calculated ~7.65 mM. Pyridoxal 5′-phosphate (PLP) acted as the best cofactor for GAD. Optimum temperature and PLP dosing were deferring for crude and purified enzyme forms which respectively exhibited at 45°C, 55°C, 200 µmol and 20 µmol whereas optimum pH was the same at 4.5. GAD finds applications in food industries hence its detailed characterization would be promising for commercial exploitations.

Hydrodynamic cavitation (HC) coupled with persulfate (PS)-based that resulted in the synergistic degradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated marine sediments. The effects of HC injection pressure and Σ[PAH]: [PS] on the rate and extent of PAH degradation were studied in the pressure range of 0.5–2.0 bar, PS concentration rage of 2 × 10−4 to 2 × 10−2 M or Σ[PAH]: [PS] of 1:10–1000, and reaction time of 20–60 min. A pseudo-first-order rate law fitted PAHs removal kinetics well. The degradation rate constant increased with injection pressure, reaching the maximum level at 0.5 bar, then decreased at injection pressure became greater than 0.5 bar. The results showed that PAH removal was 84% by the combined HC and PS process, whereas, HC alone only achieved a 43% removal of PAHs in marine sediments under the optimal inlet pressure of 0.5 bar at PS concentration of 2 × 10−2 M in 60 min. The HC‒PS system effectively removed PH, PY, FLU, BaA, and CH at 91, 99, 91, 84, and 90%, respectively. The maximum removal of 6-, 5-, 4-, 3-, and 2-ring PAHs was 89, 87, 84, 76, and 34%, respectively. Major reactive oxygen species (ROSs), namely, SO4−• and HO•, were responsible for PAHs degradation. Results clearly highlighted the feasibility of HC−PS system for the clean-up of PAHs-laden sediments in particular and other recalcitrant organic contaminants in general.

Sediment is an important final repository of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Herein, a novel catalyst of LaFeO3 nanoparticles supported on biochar was synthesized from water caltrop shell by chemical precipitation. The composite (LFBC) was used as peroxymonosulfate (PMS) activator to oxidize PAHs in real marine sediments. Systematic surface characterization confirmed the immobilization of well crystalline nano LaFeO3 particles onto the biochar surface. Under optimal conditions, i.e., [PMS] = 3 × 10-4 M, [LFBC] = 0.75 g/L, pH 6.0, and seawater, the total PAH degradation efficiency was 90%, while that of 2-, 3-, 4-, 5-, and 6-ring PAHs was 52%, 61%, 66%, 56%, and 29%, respectively, in 24 h. The Langmuir-Hinshelwood equation better predicted the PAHs degradation kinetics over LFBC by PMS. Interactions between surface oxygen species at LaFeO3 defective sites and the graphitized biochar network facilitated the PAHs degradation. Furthermore, changes in the bacterial community during the LFBC/PMS treatment were highlighted to assess the sustainable development of the sediment ecosystem. The LFBC/PMS process enhanced the biological richness and diversity of sediment eco-systems. The major phylum was Proteobacteria initially, while Hyphomonas was the genera after LFBC/PMS treatment of the sediment.

Antibiotics improve the quality of human life but their intrusion into water matrices comes with adverse effects on natural bacterial communities that may result in the proliferation of antibiotic resistant bacteria and antibiotic resistance genes. Hence, antibiotic-laden wastewaters require adequate treatment prior to their release to the natural environment. Herein, we investigate the degradation of tetracycline (TC) antibiotics in aqueous solutions by ferrous ion-catalyzed oxidation in the presence of sodium percarbonate (SPC). Control experiments without Fe2+ but with SPC, and vice versa resulted in negligible TC removal. The effects of reactant dosing and solution pH on the extent and rate of TC removal were examined. Hydroxyl radicals were the dominant reactive oxygen species (ROS) identified from indirect ROS scavenging experiments and confirmed by electron paramagnetic resonance analysis. Treatment of actual wastewaters was simulated by adding chloride, nitrite, nitrate and ammonium ions to the water matrix at varying concentrations and their effects on TC removal were examined. Negligible impact on TC degradation was noted for N-species while chloride ion accelerated degradation kinetics and reached complete tetracycline abatement in 10 min. Residual chemical analysis showed continued Fe2+ consumption and H2O2 production even with complete tetracycline elimination. Experimental results showed complete abatement of 0.2 mM TC with k1 of 9.3 × 10−2 min−1 and over 40% TOC removal in 45 min of treatment under optimized conditions of 0.5 mM of Fe2+, 0.75 mM SPC, at pH 3.0. The study showed the effectiveness of percarbonate oxidation as a tertiary treatment technology and the results can be used in designing treatment systems for wastewaters containing antibiotics and other pharmaceuticals.

Based on the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (the Ballast Water Management Convention, or BWM Convention) of the International Maritime Organization, from 8 September 2017, all ships must have an approved Ballast Water Management Treatment System (BWTS) to prevent the invasion of alien species through the discharge of ballast. Generally speaking, the need for an approved BWTS is limited to large vessels, as they are too large or too expensive for small vessels to install. This study aims to propose a simple ballast-free approach for small vessels (e.g., tugs, workboats, research vessels) that require ballast to compensate for the weight loss of fuel when sailing. Our approach involves refitting the dedicated ballast tank of these small vessels to be drinking water tanks and filling the tanks with onboard-generated distilled or reverse osmosis water to adjust the stability of the ships. We assessed our approach using three vessels. Two ships using our proposed method were certified by the American Bureau of Shipping as containing no ballast water tank, and not being subject to the BWM Convention. This study provides an environmentally harmless, easy to use, and economical approach for small vessels to comply with the BWM Convention.