Journal of Environmental Engineering

In megacities and urban areas, grilling restaurants have been recognized as major sources of particulate matter (PM) with an aerodynamic diameter under 2.5 μm (${\mathrm{PM}}_{2.5}$). To reduce PM emissions from grilling fumes, we developed and evaluated the performance of both multicompartment (M-type) and mirror-symmetrical multicompartment (MSM-type) scrubbers. M-type scrubbers exhibited a PM removal efficiency of $95.7\%\pm 3.7\%$ at a fume flow rate of ${6\mathrm{m}}^3/\min$ and a water level of 10 cm, whereas the PM removal efficiency of MSM-type scrubbers was 95.3%±32.5% at a gas flow rate of ${12\mathrm{m}}^3/\min$ and a water level of 10 cm. The design parameters for the M-type and MSM-type scrubbers were compared with the parameters for conventional single-type (S-type) scrubbers. Each design parameter for each scrubber was calculated so that the PM in the grilling fumes at a flow rate of ${30\mathrm{m}}^3/\min$ could be removed at a >95%rate. The equipment volumes were 2.02, 0.54, and ${0.47\mathrm{m}}^3$ for the S-type, M-type, and MSM-type scrubbers, respectively. The MSM-type scrubber pressure drop was the lowest ($141\mathrm{mm}{\mathrm{H}}_2\mathrm{O}$), followed by the M-type scrubber ($162\mathrm{mm}{\mathrm{H}}_2\mathrm{O}$), and, finally, the S-type scrubber ($220\mathrm{mm}{\mathrm{H}}_2\mathrm{O}$). These results demonstrate that the MSM-type scrubber represents a promising technology for PM reduction from grilling fumes thanks to its compact design, simple operation, and satisfactory PM removal performance.

Black putrid river water is often found in densely populated regions with rapid economic development and population growth. This study proposes immobilized native photosynthetic bacteria (PSB), a group of bacteria that can survive in and simultaneously purify a wide range of polluted water bodies, as a novel method for treating heavily polluted river water. A native photosynthetic bacterial (PSB) colony that is a mixture of Rhodovulum strictum and Thiococcus pfennigii was isolated from river sediment (River Zaoyu, Beijing), enriched, and immobilized to purify heavily polluted river water. Consequently, the immobilized PSB was used to treat heavily polluted river water (from the River Zaoyu), with results showing a 70.5% reduction in chemical oxygen demand (COD) in 120 h. The removal efficiency of sulfide and ammonia nitrogen reached 91.7% and 28.3% in 48 and 24 h, respectively. In addition, the dissolved oxygen concentration rose from 0.31 to $1.52\mathrm{mg}{\mathrm{L}}^{-1}$ in 48 h. Moreover, the heavily polluted river water became much less turbid following immobilized PSB treatment. This study demonstrates that the applicability of PSB in purifying heavily polluted river and immobilizing microorganisms like the PSB could be a prospective approach to enhance their performance in water bodies with low carbon, low dissolved oxygen (DO), high nitrogen, and high phosphorus.

A series of floating beds consisting of biounits were constructed for eutrophic water treatment in the field. Dynamic changes in water quality under each treatment were monitored to investigate treatment performance, and the mass balances of nitrogen (N) and phosphorus (P) in the integrated ecological floating bed (IEFB) were studied to reveal the interaction mechanisms operating within the beds. Water quality improvement was examined under different biounit arrangements to optimize configuration parameters. The test results showed that the concentrations of total nitrogen (TN) and total phosphorus (TP) declined linearly during the first 6 days, and the highest removal of TN (58.9%) and TP (59.1%) was observed in the IEFB, in which TN and TP removal rates reached up to 0.407 and $0.041\mathrm{mg}·{\mathrm{L}}^{-1}·{\mathrm{day}}^{-1}$, respectively. The mass balance analysis of N/P indicated that TN was mainly removed through microbial denitrification (72.5%), with sedimentation accounting for 59.1% of TP removal. Compared with each independent biounit, the IEFB composed of multiple biounits exhibited superior performance in eutrophic water purification. The removal of N and P in the IEFB mainly depended on the bacteria and algae attached to the artificial carrier medium. Meanwhile, the aquatic animal unit enhanced the removal efficiency of TN and TP from the water by means of inorganization of particle N and P, which simultaneously improved water diaphaneity.

An integrated experimental-numerical approach is used in this study to bioremediate a toluene, a nonaqueous phase liquid (NAPL), contaminated land site, having varying moisture and temperature levels. The rates of biodegradation in saturated and unsaturated zones under varying soil-moisture (100% to 20%) and temperature ($30°\mathrm{C}\pm 2°\mathrm{C}$ and $10°\mathrm{C}\pm 0.5°\mathrm{C}$) conditions are obtained by conducting a series of laboratory experiments first. Thereafter, an integrated approach for engineered bioremediation of a characteristic polluted subsurface site is developed considering a system of injection-extraction wells and a HYDRUS three-dimensional (3D) simulator. The injection-extraction wells system is optimally designed to enhance the natural bioremediation rate by having three injection wells and one extraction well to provide additional oxygen supply to the contaminated zone and to contain the NAPL plume in the treatment zone. The pumping rates for injection and extraction wells are optimized using an extreme learning machine-particle swarm optimization-based simulation-optimization approach (ELM-PSO). The results show that the biodegradation rates are high at 30°C for the polluted site having soil moisture content around field capacity. The degradation rate is reduced significantly at a lower temperature of 10°C, particularly when the soil moisture content is kept in the low (40%–20%) range. The designed injection-extraction well system shows that almost similar costs of remediation are required when the soil moisture content is maintained in the range of 60%–80% of the saturation level at a high (30°C) temperature. No substantial change in the time of remediation is observed by changing the soil moisture content between 60% and 80% at this high temperature. However, an elongated time period of treatment observed at a 60% moisture content as compared to the 80% level at a low (10°C) temperature indicates the dominant role of temperature stress as compared with the soil moisture availability. Further, this combination takes about 66% less time in remediating the pollutant concentration to an acceptable level than the time required at the low temperature and moisture content levels. The findings of this study are of direct use in planning remediation strategies for hydrocarbon contaminated sites.

The cathode chamber of a dual-chamber electrochemical reactor separated by DuPont proton exchange membrane, which has a higher reductive capacity than a single-chamber reactor, has a remarkable reduction effect on carbon tetrachloride. In this work, the effects of different electrodes, cell voltage, temperature, electrolyte concentration, and initial pH on carbon tetrachloride (${\mathrm{CCl}}_4$, CT) removal in wastewater were investigated. It was found that when the ${\mathrm{IrO}}_2\text{-}{\mathrm{RuO}}_2/\mathrm{Ti}$ electrode was the anode and the Fe electrode was the cathode, a satisfactory CT removal was obtained within 180 min, and this process was consistent with the first-order reaction kinetics. Under optimal application conditions, the removal of $1\mathrm{mg}/\mathrm{L}$ CT within 180 min was $97.98(\pm 1.21)\%$, the total organic carbon removal rate was 41.77%, the reductive products were mainly chloroform (CHCl₃, CF) and dichloromethane (CH₂Cl₂, DCM), and this efficiency is superior to that of a single chamber. Therefore, this technique could rapidly dechlorinate and detoxify CT while preventing CT from escaping and damaging the atmospheric environment.

Fouling remains a critical barrier for the continued development of forward-osmosis (FO) membrane bioreactor technology (MBR). Thermal osmotic backwashing at 23°C, 60°C, and 80°C, coupled air scouring, and the impact of frequency and duration of ambient (23°C) osmotic backwashing were evaluated as nonchemical methods for mitigation and removal of biological fouling in an FO-MBR. Results demonstrate that backwashing at elevated temperatures increases the immediate water flux recovery by 7% but does not provide mid- or long-term productivity improvements when compared to ambient temperature backwashing. Constant air scouring was the most effective for minimizing fouling in a bench-scale FO-MBR process; however, a full-scale energy analysis revealed that the high capital and operating costs of constant scouring outweigh the water productivity gains observed. Optimization of ambient backwashing duration and frequency was the most economically efficient FO-MBR fouling mitigation approach.

This report describes a method encompassing the generation of active chlorine species combined with the activity of a novel polyferric flocculation agent, which exhibits potential for the degradation of organic pollutants in oilfield wastewater. This process takes advantage of electrochemical (anodic) oxidation reactions to degrade oilfield wastewater pollutants with simultaneous generation of active chlorine species from NaCl in the electrolyte. Divalent iron ions are oxidized by active chlorine species, generating the new polyferric species. The flocculation activity of the newly-formed polyferric species demonstrates efficient reduction of the chemical oxygen demand (COD) of wastewater samples. The strong point of this process is that active chlorine species can be produced over short electrolysis times and at low voltage intensities. Overall, the novel polyferric species demonstrates better flocculation effects than traditional ferric flocculants. Specifically, it achieves 87.36% COD reduction after $50\min$ of electrolysis with a voltage intensity of $20\mathrm{V}$, and after the electrolysis was stopped and ferrous ions were added to the system for 1 h, achieved results which were 3.38 times higher than the treatment of oilfield wastewater using a traditional polyferric flocculation method. The strategy described herein can effectively reduce the COD content in oilfield wastewater.

This study focuses on using wastewater-based epidemiology to provide early warnings of the second COVID-19 wave in the Detroit metropolitan area of Michigan. SARS-CoV-2 RNA from untreated wastewater samples was compared to reported public health records. Untreated wastewater samples were collected from the Great Lakes Water Authority (GLWA) Water Resource Recovery Facility (WRRF), located in southeast Michigan, between August 6, 2020 and December 14, 2020. The WRRF receives wastewater from its service area via three main interceptors: the Detroit River Interceptor (DRI), the North Interceptor-East Arm (NIEA), and the Oakwood-Northwest-Wayne County Interceptor (ONWI). A total of 144 untreated wastewater samples were collected (45, 48, and 51 for ONWI, NIEA, and DRI, respectively) at the point of intake into the WRRF. Virus-selective sampling was conducted, and viruses were isolated from wastewater using electropositive NanoCeram column filters. For each sample, an average of 33 L of wastewater was passed through NanoCeram electropositive cartridge filters at an average rate of

$4.45\times {10}^4$

$5.30\times {10}^6$