Journal of Environmental Engineering

In the present study, ibuprofen (nonsteroidal anti-inflammatory drug) removal was investigated by means of electrochemically activated peroxymonosulfate (EC/PMS) using iron as the sacrificial anode in the reverse-osmosis concentrate (ROC). Complete ibuprofen (IBU) removal was achieved in 30 min at near neutral pH with $[\mathrm{PMS}{]}_0=500\mathrm{mg}/\mathrm{L}$ and current density $(\mathrm{CD})=2.5\mathrm{mA}/{\mathrm{cm}}^2$ using the EC/PMS process. EC/PMS performed extremely well in comparison with PMS alone, electrocoagulation (EC) alone, or ${\mathrm{FeSO}}_4/\mathrm{PMS}$ where ${\mathrm{FeSO}}_4$ was added at the beginning. However, when ${\mathrm{FeSO}}_4$ was added stepwise, PMS activation was more efficient, and the IBU removal rate was close to that of EC/PMS. A response-surface methodology was carried out to understand the effects of pH, $[\mathrm{PMS}{]}_0$, and CD on %IBU removal over 30 min and removal rate constants. It was observed that acidic initial pH, lesser $[\mathrm{PMS}{]}_0$, and highest CD were favorable for higher removal rate constants. Nevertheless, a higher removal rate constant did not necessarily lead to complete removal. $[\mathrm{PMS}{]}_0$ to CD ratios significantly affected both %IBU removal and the removal rate constant in the batch EC/PMS process. The EC/PMS process functioned quite well in continuous flow mode. The increase in flow rate from 2 to $4\mathrm{L}/\mathrm{h}$ provided higher %IBU removal from 96.5% to 99.5%, and the residual ${\mathrm{Fe}}^{2+}$ was reduced from 10 to $3\mathrm{mg}/\mathrm{L}$, respectively. Conclusively, EC/PMS was found to be a promising green treatment method for complex organic compound removal.

In this work, the technical capabilities of lab-scale electrodialysis (ED) and the electrodeionization (EDI) processes on removing ammonia from synthetic wastewater were investigated. The overall performance of ED and EDI process in the removal of ammonia from high ammonia concentration synthetic wastewater was assessed by applied electric potential, feed concentration, and energy consumption. Under the conditions of working electric potential, ED showed that ammonia concentration could be reduced from 1,000 to $309\mathrm{mg}/\mathrm{L}$ with a best removal efficiency of 69.1%, EDI showed that the ammonia concentration could be reduced from 1,000 to $120.9\mathrm{mg}/\mathrm{L}$ with a best removal efficiency of 87.91%, the energy consumption of ED and EDI were in the range of $1.7–12.96\mathrm{Wh}/\mathrm{L}$ and $6.2–149.2\mathrm{Wh}/\mathrm{L}$, respectively. Under the conditions of feed concentration, ED and EDI obtained a best removal efficiency of 57.93% and 98.5%, respectively, the energy consumption was in the range of $9.36–53.55\mathrm{Wh}/\mathrm{L}$ and $62.7–218.1\mathrm{Wh}/\mathrm{L}$, respectively, excessive applied electric potential and concentration will lower current efficiency and increase energy consumption. The ammonia removal efficiency of EDI was found to be higher than ED, but the current efficiency of EDI was lower than ED, and the stack current of EDI increased quickly under constant voltage when the feed concentration was over $\mathrm{1,000}\mathrm{mg}/\mathrm{L}$. The results showed that EDI was suitable for low concentration solution treatment, whereas ED was suitable for high concentration solution treatment. As a novel technology of groundwater contamination treatment, the process was proved to be feasible and provided foundation for further research.

Citizen science has been increasingly applied in environmental monitoring projects as a way to address large-scale social-environmental problems, including a lack of awareness of such problems as well as the capacity for using science to inform decision making. While studies have found that citizen science can help improve environmental literacy and engage participants, knowledge about the extent of such changes in environmental literacy and behaviors as well as how these changes are influenced by participants’ socioeconomic characteristics remains limited. In response, we have developed a contest-based citizen science study focused on drinking water quality data collection and education. We sought to understand how socioeconomic characteristics affect participant knowledge in the context of drinking water quality and lead contamination, willingness to take preventative actions to improve health protection, and frequency of communication about water quality issues with those around them. Comparison of pre- and post-surveys showed statistically significant increases in participants’ likelihood to communicate about drinking water. With respect to knowledge, this project showed success in improving scientific literacy relating to key lead information and provided self-assessed educational benefits to those who participated. This project demonstrates that citizen science methods could be used to actively engage and inform participants in water quality monitoring efforts, creating a more scientifically literate and active public.

The soil microbial community is highly sensitive to the soil environment and can reflect changes in soil quality and soil ecosystem health. To clarify the differences in microbial structure and the effect of environmental factors on soil microbial communities in different ecological regions in Golden Maize Belt China, 72 corn soils were collected in three ecological zones (eastern, central, and western) in Jilin province. The chemical properties and enzyme content were measured. High-throughput sequencing was adopted to calculate the microbial diversity and analyze the microbial structure of soil fungi and bacteria. The environmental influencing factors were found by canonical correlation analysis. The results showed that the soil pH of the eastern, central, and western regions is 5.3, 6.2, and 7.9, respectively. Soil fertility declined from east to west. The content of urease and sucrase in the soil in the west was the highest at $48.11\mathrm{mg}/\mathrm{g}·\mathrm{d}$ and $119.23\mathrm{mg}/\mathrm{g}·\mathrm{d}$, respectively. Soil phosphatase content was closely related to soil pH. The abundance of fungal and bacterial communities displayed a downward trend from west to east. Ascomycota is the dominant flora of soil fungi, and Actinobacteria is the dominant flora of soil bacteria. The Ascomycota and Actinobacteria showed a positive correlation with loam. The accumulated and annual average temperatures in environmental factors had the most significant influence on the structure of the soil fungal. Soil pH, alkali hydrolyzed nitrogen, and rainfall were the main factors affecting the soil bacteria. Our findings emphasize that climatic conditions significantly impact soil fungi and bacteria. Therefore, we should pay great attention to the impact of climate change on soil microbial diversity and structure.

The addition of iron oxides in anaerobic digestion can increase conversion efficiency. In this study, we investigated the effects of the addition of ${\mathrm{Fe}}_2{\mathrm{O}}_3$, ${\mathrm{Fe}}_2{\mathrm{O}}_3$ nanoparticles, ${\mathrm{Fe}}_3{\mathrm{O}}_4$, and ${\mathrm{Fe}}_3{\mathrm{O}}_4$ nanoparticles with different concentrations (0.5%–1.5%) on the anaerobic codigestion of a Pennisetum hybrid and kitchen waste in a batch-mode mesophilic experiment. The results indicated that the additives with different valence states and particle sizes had different effects on the anaerobic codigestion of the Pennisetum hybrid and kitchen waste. The addition of 0.5% ${\mathrm{Fe}}_2{\mathrm{O}}_3$ [with a biogas production of $286.0\pm 61.8\mathrm{mL}/\mathrm{g}$ volatile solid (VS)] and 0.5% ${\mathrm{Fe}}_3{\mathrm{O}}_4$ (with a biogas production of $309.1\pm 22.3\mathrm{mL}/\mathrm{g}$ VS) improved the cumulative biogas yield by 23.5% and 37.9%, respectively, compared with that of the control group (with a biogas production of $237.2\pm 30.1\mathrm{mL}/\mathrm{g}$ VS). Further correlation analysis showed that pH and total ammonia nitrogen were positively correlated with cumulative biogas yield, whereas bicarbonate alkalinity concentration/volatile alkalinity concentration and volatile fatty acids were negatively correlated with cumulative biogas yield. This study provided insights on anaerobic codigestion of the Pennisetum hybrid and kitchen waste in the presence of iron oxides, which will be beneficial for further studies in the field of renewable energy production.

In the US Virgin Islands (USVI), roof-harvested rainwater is a primary source of domestic water and is collected in large cisterns and pumped throughout the household premise plumbing system. However, previous literature suggests that roof-harvest rainwater is prone to microbial contamination. A common local water treatment practice is direct batch chlorination of this water ($>\mathrm{20,000}$ L). Provided this local habit, Love City Strong (LCS) established a pilot program to evaluate if direct batch chlorination of water in cisterns was effective and economically feasible to produce consistently adequate levels of free chlorine residual (FCR) at the kitchen tap. A trained field team utilized nine actively used cisterns to conduct a series of chlorine dosing trials where the cistern water was dosed, and, subsequently, monitored every three days. Water quality data were collected throughout, and new trials were initiated once FCR values reached $\le 0.05\mathrm{ppm}$. Evaluation criteria included: (1) the variability in duration between a dosing event and an FCR measurement $<0.2\mathrm{ppm}$, (2) the variability of achieving a target FCR level of 1.5 ppm, (3) the variability in the first-order chlorine decay rate, and (4) the costs of the method. Results suggested that the variability in duration, achieving a target FCR, and the decay rate were prohibitively high for consistent use of the method. The duration ranged from 3 to 33 days (mean: 11.5; $\mathrm{n}=34$). This large range may have been influenced by the low probability (18%) of achieving an initial target FCR between 1.25 and 1.75 ppm. In addition, the chlorine decay rate ranged from 0.095 to $0.482{\mathrm{d}}^{-1}$ (mean: $0.251{\mathrm{d}}^{-1}$), resulting in an estimated duration ranging between 5 and 22 days. Finally, the first-year cost was $622 ($244 excluding person-time costs), while annual costs thereafter were $567 ($204 excluding person-time costs). Given these data, we do not recommend the use of direct batch chlorination for treating cistern water for microbial contamination in USVI households.

Low impact development (LID) provides a new way to address the problems of urban nonpoint source pollution and storm flood management. Implementation of LID measures is challenging due to the variation of characteristics in different watersheds, such as budget, size, number, location, and combination. Traditional bioretention soil media (BSM) is defined as a mixture in which the mass ratio of local river sand, soil, and wood chips is $65:30:5$. A certain proportion of modifiers with better adsorption effects was added to the traditional BSM to prepare an improved BSM. The media infiltration capacity, ponding depth, and discharge ratio (catchment area/facility area) were key design parameters affecting watershed management of urban hydrologics in loess regions. Therefore, a numerical calculation method of ponding depth and discharge ratio was proposed in this study to evaluate the effects of media modification on the system. Under the design condition of a 60-min rainfall duration and two-year recurrence interval, a limitation of the ponding depth and duration to 15 cm and 20 min, respectively, should result in the discharge ratios of planting soil, $\mathrm{BSM}+10\%$ water treatment residuals (WTR), and $\mathrm{BSM}+10\%$ fly ash to be $\le 5:1$, $\le 20:1$, and $\le 10:1$, respectively. The sensitive parameters were identified and verified through a pilot test and soil physical model HYDRUS simulation, in which the calibrated and validated model can be used to predict the thickness of modified media under different runoff volume and pollutant reduction design objectives.

Abstract

We studied the relationship between the change of methylmercury (MeHg) content and the number of sulfate-reducing bacteria (SRB) in Suaeda Heteroptera soil with different salinity at 20°C and 30°C. Salinity variation affects soil methylmercury content. We studied whether temperature variation is the dominant factor in SRB affecting mercury methylation. Our research shows that proper salinity favored the production of MeHg in soil; appropriate temperature increase could enhance SRB activity and MeHg output, and the mercury methylation effect of SRB was more significant at 30°C. SRB was present in the test soils at different salinities, and the amount of SRB did not vary regularly in the flooded salinity gradient. The SRB content in the culture soil was higher at 30°C than at 20°C. There was no significant correlation between SRB numbers and MeHg in the culture soil at 20°C. Soil MeHg content and SRB count had a significant positive correlation in the first 15 days of incubation at 30°C, whereas there was no correlation between the two in the later period.

Practical Applications

Suaeda Heteroptera Kitag wetlands are a typical wetland type in the Liaohe estuary. Recently, with the development of paddy fields, freshwater resources in Liaohe estuary have decreased year by year, soil salinity has increased, and Suaeda Heteroptera Kitag wetland has degraded year by year, and increasing salinity is the main reason for alkali poncho degradation. With the global warming, high temperatures in Liaoning have increased. Sulfate-reducing bacteria are important influencing factors of mercury methylation, while salinity and temperature changes affect methylmercury (MeHg) and SRB content. Therefore, understanding the effects of different salinity gradients on methylmercury and SRB at a certain temperature will help to reduce mercury methylation. However, it is difficult to achieve the salinity gradient required in the actual environment, so indoor simulation experiments are used for research. Our results showed that proper salinity favors the production of MeHg in soil, proper elevated temperature increases the activity of SRB and MeHg production, and the methylation of Hg by SRB is more pronounced at 30°C. SRB was present in the soil under all salinity conditions, and the amount of SRB in the soil did not change regularly with increasing salinity of flooded water.