The aim of this study was to evaluate changes in hematological parameters of O. niloticus exposed to sublethal concentrations of the imidacloprid in order to utilize these parameters as biomarkers of exposure. Fish with an average weight of 68.5 ± 2.0 g were exposed to sublethal concentrations of imidacloprid (1.405, 2.810, 14.050, and 28.1 mg L⁻¹) for 7 days. Blood samples were collected by puncture of the tail vein. Blood samples were used to determine the number of erythrocytes, hemoglobin level, hematocrit number, total plasma protein concentration, total and differential leukocytes count, and thrombocytes number. All tested concentrations caused changes in fish leukogram. Concentrations from 14.050 mg L⁻¹ reduced the number of erythrocytes and total plasma proteins. The tilapia exposed to 28.1 mg L⁻¹ had a significant increase in the number of thrombocytes. Although considered slightly toxic to fish, sublethal concentrations of imidacloprid in aquatic environments, even if it does not cause immediate death, may compromise the health and long-term survival of these animals. The sublethal responses adopted for evaluation toxicity in this study were sensitive and adequate to show the extent to which pesticide can affect non-target organisms. This study recommends the use of blood parameters as biomarkers of exposure of fish to pesticides.

Due to the dramatically increasing production of excess sludge during biological wastewater treatment, the development of an economical, efficient, and environmentally friendly sludge dewatering method is highly required. Herein, Bdellovibrio-and-like organisms (BALOs), a group of predatory bacteria were applied for waste sludge dewaterability enhancement and biomass reduction and the potential biolysis mechanisms were elaborated. Generally, the satisfying biolysis performance was obtained for the sludge with the moderate total solid (TS) content (1.5–2.5%). Within 24-h sludge biolysis with our isolated and enriched BALOs, the sludge specific resistance to filtration value as the dewaterbility index reached the maximal reduction rate of 65.3 ± 6.4%. Meanwhile, the concentrations of released soluble nitrogen and phosphorous significantly increased by 57.4 ± 3.3 and 56.7 ± 6.1%, respectively. Moreover, the contents of tightly bound extracellular polymeric substances (EPS) dramatically decreased after sludge biolysis while the loosely bound EPS contents increased, which implied the disruptions of sludge flocs structure for sludge dewaterability improvement. High-throughput sequencing results revealed the remarkable shift of sludge’s microbial community structure after biolysis treatment. The relative abundances of the dominant genera Ferruginibacter, Pseudomonas, and Thermomonas related to denitrification or flocs structure stabilization dramatically decreased. The noticeable increasing populations of Comamonas and Hyphomicrobium in abundances suggested the potential re-growth of the surviving microbial cells in response to BALO invasions. Overall, BALO predation could disintegrate the waste sludge structure, promote the cell lysis and the intracellular substances release, and cause the variations of microbial community compositions to efficiently improve the sludge dewaterability.

Aquatic organisms might be exposed episodically or continuously to chemicals for long-term periods throughout their life span. Pesticides are one example of widely used chemicals and thus represent a potential hazard to aquatic organisms. In addition, these chemicals may be present simultaneously in the environment or as pulses, being difficult to predict accurately how their joint effects will take place. Therefore, the aim of the present study was to investigate how Daphnia magna (clone k6) exposed throughout generations to a model pesticide (the fungicide carbendazim) would react upon an exposure to another chemical compound (triclosan) and to a mixture of both chemicals (carbendazim and triclosan). Responses of daphnids continuously exposed to carbendazim and kept in clean medium will be compared using immobilization tests and the comet assay (DNA integrity). The results showed that triclosan presented similar toxicity to daphnids exposed for 12 generations (F12) to carbendazim (similar 48-h-LC₅₀ values for immobilization data), when compared with daphnids kept in clean medium. However, at subcellular level, daphnids previously exposed to carbendazim for 12 generations (F12) showed different responses than those from clean medium, presenting a higher toxicity; a general higher percentage of DNA damage was observed, after exposure to a range of concentrations of triclosan and to the binary combination of triclosan + carbendazim. The patterns of toxicity observed for the binary mixture triclosan + carbendazim were generally similar for daphnids in clean medium and daphnids exposed to carbendazim, with a dose level deviation with antagonism observed at low doses of the chemical mixture for the immobilization data and a dose ratio deviation with synergism mainly caused by triclosan for DNA damage. With this study, we contributed to the knowledge on long-term induced effects of carbendazim exposure, while looking at the organismal sensitivity to another chemical (triclosan) and to a mixture of carbendazim and triclosan using lethality as an endpoint at the individual level and DNA damage as a subcellular endpoint.

Hydrothermal treatment (HTT) of sewage sludge (SS) with pig manure biochar (PMB) addition at 160–200 °C was conducted in this study. The effects of PMB addition on the dewaterability of SS and the speciation evolution, leaching toxicity, and potential ecological risk of heavy metals were investigated. The results showed that the solid contents of the filter cakes after adding PMB increased from 20.24%, 24.03%, and 28.69% to 21.57%, 27.69%, and 32.91% at 160, 180, and 200 °C, respectively, compared with traditional HTT of SS. Furthermore, PMB could reduce the bioavailable fractions of Cr, Ni, As, and Cd in the filter cakes obtained at 160 and 180 °C compared with the theoretical value. The leaching toxicity of heavy metals in the filter cakes after adding PMB decreased significantly at 160 and 180 °C and the potential ecological risk index (RI) declined from 62.13 and 44.83 to 55.93 and 42.11, respectively. The obtained filter cake had low potential ecological risk when used in the environment. The mechanisms on the improvement of the dewaterability and heavy metals immobilization were related that PMB acted as the skeleton builder providing the outflow path for free water and implanting heavy metals into SS structure. And the optimal results were obtained at 180 °C during HTT of SS with PMB addition. This work provides a novel and effective method for the treatment of SS.

As an important role in economic development in China, industrial parks have consumed plenty of energy, while emitting enormous air pollutants and discharging large quantities of waste heat. Energy cascade utilization is an effective way to improve the energy efficiency of industrial parks. The objective of this study was to assess the co-benefits of energy cascade utilization, including the energy savings potential, reduction potential of air pollutants, and air quality improvements, in an industrial park in China. Through an energy flow analysis of steam at different pressures and residual gas among various enterprises, this study identified the existing energy cascade utilization network in a baseline scenario and proposed an enhanced scenario. To evaluate the co-benefits of these two scenarios, the CALPUFF model was used to integrate energy savings and air pollutant mitigation for the park in 2017. The results show that energy cascade utilization can result in considerable co-benefits related to energy conservation, air pollutant emission reductions, and air quality improvements. In the enhanced scenario, the total energy savings potential is 11,425 TJ, with emission reductions of 859 tons of SO₂ and 910 tons of NOₓ. Based on the CALPUFF simulations of SO₂ and NOₓ diffusion in the four seasons, the concentrations of SO₂ and NOₓ in the study area considerably decreased in the enhanced scenario compared with those in the baseline scenario. This study demonstrates that the park should focus on the cascade utilization of waste heat and residual gas to improve the energy utilization efficiency and reduce atmospheric pollutant emissions.

We performed a time series analysis to investigate the potential association between exposure to ambient air pollution and type 2 diabetes (T2D) incidence in the Chinese population. Monthly time series data between 2008 and 2015 on ambient air pollutants and incident T2D (N = 25,130) were obtained from the Environment Monitoring Center of Ningbo and the Chronic Disease Surveillance System of Ningbo. Relative risks (RRs) and 95% confidence intervals (95% CIs) of incident T2D per 10 μg/m³ increases in ambient air pollutants were estimated from Poisson generalized additive models. Exposure to particulate matter < 10 μm (PM₁₀) and sulfur dioxide (SO₂) was associated with increased T2D incidence. The relative risks (RRs) of each increment in 10 μg/m³ of PM₁₀ and SO₂ were 1.62 (95% CI, 1.16–2.28) and 1.63 (95% CI, 1.12–2.38) for overall participants, whereas for ozone (O₃) exposure, the RRs were 0.78 (95% CI, 0.68–0.90) for overall participants, 0.78 (95% CI, 0.69–0.90) for males, and 0.78 (95% CI, 0.67–0.91) for females, respectively. Exposure to PM₁₀ and SO₂ is positively associated with T2D incidence, whereas O₃ is negatively associated with T2D incidence.

Electronic waste (e-waste) has been widely studied by scholars all over the world, but the research topics and development trends in this field are still unclear. This study aimed to explore the status quo, hot topics, and future prospects in the field of e-waste. Data of publications were downloaded from the Web of Science Core Collection. We used CiteSpace V, Histcite, and VOSviewer to analyze literature information. A total of 2800 papers in e-waste research were identified, and the number of publications increased rapidly after 2004. Six thousand five hundred seventy-three authors participated in the e-waste research, but 70.01% of the authors published only 1 article. The most productive country in this field was China (1146 publications), and the most productive institution was the Chinese Academy of Sciences (370 publications). The Waste Management (225 publications) was the most productive journal, and Environment Science & Technology (9704 co-citations) was the most co-cited journal. The main hot topics in e-waste field were management and recycling of e-waste in developing countries, health risk assessment after exposure to organic pollutants, degradation and recovery of waste metal materials, and impact of heavy metals on children’s health. The frontier topic was degradation.

Increasing applications of rare earth elements (REEs) and improving technologies have led to increased demand. Because of their limited availability and depletion of most resources, the recovery of these elements from waste has become important. The use of cost-effective materials for this purpose and the high value that can potentially be recovered would be beneficial and attractive to many industries using REEs. In this study, natural zeolite and bentonite were used in batch studies to recover REEs (La, Y, Lu, Sm, Pr, Tm, Ce, Nd, Yb, Gd, Eu, Er, Ho, Dy, and Sc) from aqueous solutions. The effect of adsorbent dosage, pH, concentration, contact time, and competing ions on recovery was investigated. Desorption studies were conducted using ammonium sulphate. Adsorption onto zeolite was found to increase with pH, whereas uniform adsorption was observed for bentonite, except at pH 2 (16% less efficiency). The pH values of 6.2 and 3.2 were selected as the optimum for zeolite and bentonite, respectively. For zeolite, the average adsorption efficiencies for REEs at 0.5, 1.0, 2.0, 5.0, and 10 mg L⁻¹ were found to be 91, 96, 89, 40, and 20% respectively but, > 98% adsorption efficiencies were achieved with bentonite at all concentrations. The zeolite and bentonite adsorption data were better described by Langmuir though, for bentonite, the coefficients of determination (R² values) for the Freundlich and Dubinin-Radushkevich isotherm models were also significant. There was no significant difference (p > 0.05) on the adsorption of the elements in the presence of competing ions. Bentonite proved to perform better, most likely as a result of its higher surface area. Generally, the good adsorption performance of both adsorbents in their natural forms makes them an attractive and potential cheap option for the recovery of REEs from wastewaters.

This study applies asymmetric causality to renewable energy (REC), carbon dioxide emissions (CE), and real GDP using non-linear broadcasting between these variables through the non-linear autoregressive distributed lag model (NARDL) to examine the short- and long-run asymmetries in the inconsistency of greenhouse gas emissions among the variables and to unpack the asymmetric causality of selective variables through positive and negative shocks for time series data from the Kingdom of Saudi Arabia between 1990 and 2014. The bounds cointegration test shows the existence of long-term dealings among all considered variables in the presence of asymmetry. The non-linear asymmetric causality test shows that negative shocks in carbon dioxide emissions had only positive impacts on real GDP in the long-term but are unobservable in the short-term. Additionally, the short- and the long-term incidences of positive shocks on real GDP are not similar to the negative shock to REC, implying the existence of asymmetric impacts on REC in both short- and long-term forms. Finally, the asymmetric causal relationship from carbon dioxide emissions to REC is neutral in the long-term. Both positive and negative shocks to REC consistently had an adverse effect on CE in the long-term. The presence of asymmetry between economic growth, CE, and REC could be of major substantial for more helpful policymakers and the action plan of sustainable development goals (SDGs) in Saudi Arabia.