Oxytetracycline (OTC) is a broad-spectrum antibiotic that resists biodegradation and poses a risk to the ecosystem. This study investigated the degradation of OTC by heat-activated peroxydisulfate (PDS) and peroxymonosulfate (PMS) processes. Response surface methodology (RSM) was used to evaluate the effect of process parameters, namely initial pH, oxidant concentration, temperature, and reaction time on the OTC removal efficiency. According to the results of the RSM models, all four independent variables were significant for both PDS and PMS processes. The optimum process parameters for the heat-activated PDS process were pH 8.9, PDS concentration 3.9 mM, temperature 72.9°C, and reaction time 26.5 min. For the heat-activated PMS process, optimum conditions were pH 9.0, PMS concentration 4.0 mM, temperature 75.0°C, and reaction time 20.0 min. The predicted OTC removal efficiencies for the PDS and PMS processes were 89.7% and 84.0%, respectively. As a result of the validation experiments conducted at optimum conditions, the obtained OTC removal efficiencies for the PDS and PMS processes were 87.6 ± 4.2 and 80.2± 4.6, respectively. PDS process has higher kinetic constants at all pH values than the PMS process. Both processes were effective in OTC removal from aqueous solution and RSM was efficient in process optimization.

Historical underground storage sites for decommissioned capacitors containing polychlorinated biphenyls (PCBs) were import sources of high-concentration PCB contaminants. However, few studies have delved into the characteristics of these sites. We investigated the wastes and cleaned-up soil, soil PCB contamination, and potential risks of 16 underground PCB-capacitor storage sites in China. Among these sites, PCB leakage occurred at all the sites with direct burial (six sites) and brick structures (three sites) and at three out of the seven sites with cement structures. From each site, an average of 60.7 t of wastes and contaminated soil were cleaned up, and the contaminated soil accounted for an average of 65.5% of the total wastes. The maximum contents of total PCBs, 12 dioxin-like PCBs (DL-PCBs), and 7 indicator PCBs (ID-PCBs) in the soil samples of each site were 51–30,700 mg/kg, 1.1–379.7 mg/kg, and 2.3–10,340 mg/kg, respectively. The total PCB and PCB congener contents in soil showed clear short-range heterogeneity as differences of up to orders of magnitude were found within a short distance (e.g., 2 m). Based on the human health risk assessment model, the maximum risks of all the sites were above the acceptable risk level (10⁻⁶). More than a half of the samples within different sites showed higher risks as per calculations with total PCB contents than for calculations with DL-PCB contents, indicating that only focusing on DL-PCBs may underestimate the potential risks for PCB-capacitor storage sites.

Estuarine sediment quality is highly associated with anthropogenic activities in watersheds. This study attempts to couple socioeconomic patterns with estuarine sediment quality via legacy organochlorines in 14 Chinese coastal watersheds. Sedimentary concentrations of HCHs, DDTs, and PCBs showed a significant spatiality in estuary, up to 48.7 ± 15.1, 89.0 ± 46.4, and 54.5 ± 17.2 ng g⁻¹, which were predominated by β-HCH, p,p′-DTs, and tri- to penta-PCBs, respectively. Ecological risk of organochlorines was negligible except few moderate risks for DDTs and PCBs against the first class quality of the marine sediment quality guidelines of China. Sedimentary DDT and PCB concentrations were significantly delineated by an environmental Kuznets curve model as a function of non-agricultural GDP per capita in watersheds, while HCHs by an increasing linear model. Findings of this study provide a tool to quantify the contribution of anthropogenic development in watershed to environmental change in estuary across the world.

This paper examines the effect of climate change and financial development on agricultural production in ASEAN-4, namely Indonesia, Malaysia, the Philippines, and Thailand from 1990 to 2016. Further, we explore the role of renewable energy, institutional quality, and human capital on agricultural production. Since the shocks in one country affect another country, we use second-generation modeling techniques to find out the relationship among the variables. The Westerlund (2007) cointegration tests confirm long-run relationship among the variables. The results from cross-sectionally augmented autoregressive distributed lag (CS-ARDL) model reveal that climate change negatively affects agricultural production; on the other hand, renewable energy, human capital, and institutional quality affect positively agricultural production. Moreover, renewable energy utilization, human capital, and intuitional quality moderates the effect of carbon emission on agricultural production. In addition, a U-shaped relationship exists between financial development and agricultural production, suggesting that financial development improves agricultural production only after reaching a certain threshold. Hence, this study suggests that ASEAN-4 countries must adopt flexible financial and agricultural policies so that farmers would be benefitted and agricultural production can be increased.

In order to understand the removal characteristics of Cl⁻ (chloride ion) in the fly ash from municipal solid waste incineration, so as to realize the harmless treatment of fly ash. The fly ash washing treatment experimental system was designed and built. The single factor experiments were used to explore the effect of liquid-to-solid ratio, washing time and temperature on the leaching rate of Cl⁻ in the fly ash. The best experimental parameters of fly ash washing were obtained. At the same time, the microscopic morphology and crystal phase composition of fly ash before and after washing were explored. The results showed that the maximum removal rate of Cl⁻ in the fly ash was 88.72% when the liquid-to-solid ratio was 8:1, the washing time was 5 min and the washing temperature was 70 ℃. It can be seen from the scanning electron microscope (SEM) image that most of the irregularly shaped square fly ash particles gradually transformed into regular spherical or elliptical shapes after washing. The X-ray diffractometer (XRD) results proved that the chlorine salt content in the fly ash after washing was significantly reduced, and the CaSO₄•2(H₂O), SiO₂, CaCO₃ and other substances were formed.

Algal organic matter (AOM) in water reservoirs is a worldwide concern for drinking water treatment; once it is one of the main precursors for disinfection by-products formation (DBPs). In this context, this study investigated the ecotoxicity of DBPs from chlorination of AOM to Ceriodaphnia silvestrii and Daphnia similis (Crustacea, Cladocera). The bioassays evaluated three scenarios, including the AOM extracted from Chlorella sorokiniana, the quenching condition used in the tests, and the DBPs formed after the chlorination of the two test waters with AOM (with and without bromide presence). The results showed that AOM has no toxic effects for the tested species under typical environmental concentration (5 mg∙L⁻¹). However, since AOM is a potential precursor of DBPs, the toxicity of two test waters (TW-1 and TW-2) after the chlorination process (25 mg Cl₂·L⁻¹, for 7 days, at 20 °C) was tested. The sample with higher toxicity to the tested species was TW-1, in which chloroform and chloral hydrate were quantified (615 and 267 µg∙L⁻¹, respectively). However, TW-2 showed lower concentration of chloroform and chloral hydrate (260 and 157 µg∙L⁻¹, respectively), although bromodichloromethane, dibromochloromethane, and bromoform were also detected (464, 366, and 141 µg∙L⁻¹, respectively). Although free chlorine is highly toxic to the tested species, the quenching conditions also affected the organisms’ survival due to the use of ascorbic acid and the presence of reaction intermediates. Nonetheless, both species were more affected by TW-1 and TW-2 than the quenching condition. These results endorse the importance of removing the AOM before the disinfection process to avoid the formation of DBPs. In addition, ecotoxicological analyses could provide a more comprehensive assessment of water quality, especially considering the challenges of quantifying DBPs and other emerging contaminants.

Heavy metals in higher concentrations are often encountered in domestic sewage of developing and under-developed countries. High metallic concentrations can stress reactor sludge biomass morphology impeding its performance in organics reduction. However, the extent of damage and ability of sludge biomass to recover from the metallic stress is not fully understood. Also, there is no protocol to identify and prevent the sludge biomass from metallic stress in fully functional sewage treatment plants (STPs). This study investigates performance, metabolic activity, morphology, and settling characteristics of the sludge biomass under different Co(II) stress conditions. The extent of recovery in biomass, when the supply of Co(II) metal ion was discontinued in the inlet stream, was explored. The study also proposed a protocol based on simple settling characteristics of sludge biomass to get an early indication of metal infiltration to prevent potential damage to the biomass morphology. Four sequencing batch reactors (SBRs) with Co(II) ion concentrations of 0 (designated as RCo0), 5 (RCo5), 25 (RCo25), and 75 mg/L (RCo75) in the feed were operated with a cycle time of 12 h. Reactors were operated for 35 days with Co(II) in the feed (termed as stressed phase operation) followed by 24 days of operation without Co(II) in the feed (termed as recovery phase operation). Results show that COD removal in reactor RCo75 reduced to 48% on the 10th day of stressed phase operation, showing a lag in COD removal due to metallic stress. The activity of biomass in reactors RCo5, RCo25, and RCo75 was reduced by 39%, 45%, and 49%, respectively, in the stressed phase compared to the biomass in control reactor. Recovery in COD removal efficiency and specific biomass activity were observed in all the reactors after the removal of metallic stress. The settleability of sludge biomass in reactors RCo25 and RCo75 was significantly affected. Transformation in the shape of flocs in reactor RCo25 and RCo75 biomasses revealed the prolonged effect of metallic stress, which was observed to be irreversible even during the recovery phase operation.

The spatio-temporal response of water quality in the receiving basins to water transfer remains unclear when considering more practical factors. Moreover, a much fast surrogate model is highly required to realize the purpose of rapid prediction of water quality. In this study, a two-dimensional hydrodynamic and water quality model was primarily established by considering the most comprehensive important pollution sources so far to investigate the water quality variation in Baiyangdian Lake, China. The pollution sources include atmospheric deposition, sediment release, village and tourism domestic sewage, livestock breeding, rainfall runoff, aquatic plants, and animals. The water quality at different sample sites was assessed using the water quality index (WQI). Subsequently, a surrogate model was proposed using the nonlinear autoregressive network with exogenous inputs (NARX), and the NARX model can realize fast prediction of the annual time series of water quality in a few seconds. The results showed that there are significant differences in water quality at different sample sites in each season. The highest WQI value occurred in autumn (65.46), and the average values at different sample sites were between 47.54 and 58.22 in this season. The water quality at Nanliuzhuang site and Caiputai site was significantly affected by water transfer patterns. In addition, the correlation coefficient R² between the predicted results and the simulated ones except that of parameter TP was larger than 0.90. The prediction performance of surrogate model was shown to be very high efficiency and accurate. The proposed models and the results of this approach are guiding significance for lake management.

The textile industry is ambitiously parading towards circularity and curtailing its dependency on fossil fuels hence the instigated research that adheres to Sustainable Developmental Goals (SDGs) and benefits the environment and human health alike. The current research experimented with innovative sources of plant-based biomaterials namely dandelion leaves, bilberry leaves, nettle leaves, and violet herb for application on cotton fabric as biomordants and colourants. The AAS analysis of mild 6% herbal solution revealed ferrous content of 6.78 mg/l in violet herb and 5.03 mg/l of the copper content in dandelion leaves applicable on cotton fabrics as biomordants thereby preventing the depletion of copper and ferrous elements mineral ores. A fair lightfastness rating and good to very good wash and rub fastness test results were obtained individually. The maximum K/S value of 13.95 was gained on cotton fabrics treated with a mild herbal infusion of bilberry leaves and coloured with violet herbs. The ATR-FTIR peak analysis noted strong = C-H bend of alkenes, strong C = O stretch of α and β unsaturated esters, and strong C-O stretch of carboxylic acids functional groups in raw herbs and its treated cotton fabrics. The dissolved oxygen (DO), oxidation–reduction potential (ORP), and potential of Hydrogen (pH) values were found in the acceptable range for all the spent solutions left after colouration of cotton fabrics with violet herbs hence sustainable. The data set obtained was statistically validated with ANOVA one-way test. Life cycle analysis and clinical investigation on potential therapeutic benefits of herbal fabrics to the wearer are suggested for future research and development.

A new one-pot synthesis method optimized by a 2³ experimental design was developed to prepare a biosorbent, sugarcane bagasse cellulose succinate pyromellitate (SBSPy), for the removal of Cu(II) and Zn(II) from single-component aqueous solutions, in batch and continuous modes. The bi-functionalization of the biosorbent with ligands of different chemical structures increased its selectivity, improving its performance for removing pollutants from contaminated water. The succinate moiety favored Cu(II) adsorption, while the pyromellitate moiety favored Zn(II) adsorption. Sugarcane bagasse (SB) and SBSPy were characterized using several techniques. Analysis by ¹³C Multi-CP SS NMR and FTIR revealed the best order of addition of each anhydride that maximized the chemical modification of SB. The maximum adsorption capacities of SBSPy for Cu(II) and Zn(II), in batch mode, were 1.19 and 0.95 mmol g⁻¹, respectively. Homogeneous surface diffusion, intraparticle diffusion, and Boyd models were used to determine the steps involved in the adsorption process. Isothermal titration calorimetry was used to assess changes in enthalpy of adsorption as a function of SBSPy surface coverage. Fixed-bed column adsorption of Cu(II) and Zn(II) was performed in three cycles, showing that SBSPy has potential to be used in water treatment. Breakthrough curves were well fitted by the Thomas and Bohart-Adams models.