Journal of Environmental Engineering

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

Acid mine drainage (AMD) is a persistent and extensive source of water pollution and ecological degradation. Cotreating municipal wastewater (MWW) with AMD using existing infrastructure at conventional wastewater treatment plants (WWTPs) may serve as a potential option for AMD abatement. However, commonly elevated iron and aluminum concentrations and low pH of AMD could negatively impact various processes at a WWTP. The focus of this mini review was on determining how cotreating MWW with AMD could impact the solids handling processes at a WWTP. While no studies have explored the solids that could be generated during cotreatment in a WWTP, numerous articles separately discuss the solids generated during AMD or MWW treatment. Reviewing this literature revealed that iron and aluminum, common metals in AMD, are already present in MWW sludge and typically benefit most solids handling processes. The addition of AMD would elevate iron and aluminum concentration but would likely result in improved sludge dewatering, removal of odor-causing compounds during processing, and a decreased bioavailability of trace metals and water-soluble P in land applications. This review concludes that cotreating MWW with moderate to low volumes ($<50\%$) of AMD at WWTPs will have minimal impact on, and likely improve, solids handling processes.

Pharmaceutically active compounds (PhACs) reaching surface waters through municipal wastewater are a concern, as existing treatment processes poorly remove them. While significant lab-scale evaluations have been performed on treatment options, full-scale tests are lacking. Presented is an experimental study from a full-scale research facility that is imbedded in a functioning municipal wastewater plant. Reverse osmosis and ozonation were tested as part of an active treatment train using secondary treated effluent from the adjoining facility. Reverse osmosis removed 92.6%, 99.0%, 99.6%, 97.8%, 99.0%, 99.6%, 99.9%, and 99.2% of metformin, cotinine, trimethoprim, caffeine, venlafaxine, carbamazepine, erythromycin, and fluoxetine, respectively. By ozone, sulfamethoxazole, carbamazepine, erythromycin and o-desmethylvenlafaxine were removed by more than 99.9%. Trimethoprim and venlafaxine were removed by more than 95%, with the remaining compounds removed by between 16% and 85%. Results demonstrate the effectiveness of reverse osmosis and ozonation for full-scale treatment.

Unit operation (UO) systems have proliferated to sequester urban drainage particulate matter (PM) and PM-bound constituents. PM has been a primary focus of testing and certification. A nominal class of UOs, hydrodynamic separator (HS) systems require less area compared with nonproprietary UOs such as basins. Physical UO testing can be costly, with years to certification. Despite protocols, controlled certification tests are subject to variability, errors, and bias and could therefore be nonrepresentative, potentially negating accurate comparisons of results. Study objectives are to develop and then test computational fluid dynamics (CFD) models as a potential complementary tool for physical test–based UO certification programs. To facilitate this objective, publically available controlled physical tests of 21 HS systems and 154 test results based on two common certification programs are synthesized, and the variability examined. PM separation from two physical-validated CFD models are compared with the results synthesized from published certification reports. Synthesized results illustrate large variability across HS systems, up to 36.9%. Additionally, results of identical HS systems are inconsistent between certification programs, with a mean relative percent difference (MPRD) as high as 32.5%. In the CFD simulations of a physically tested full-scale HS system, Eulerian-equilibrium Eulerian (EE) and Eulerian-Lagrangian (EL) models reproduce PM separation with MRPD of 2.5% and 4.4%. In conclusion, simulations of publically reported HS systems illustrate the potential of CFD models as an adjuvant evaluation tool complementing physical testing. CFD models can also provide an efficient, economical, consistent, and revisable platform for UO systems.

This study investigated the effect of gasification biochar amendment on mechanical, chemical, hydraulic, and microstructural properties of Buckshot clay, a high-plasticity clay with poor engineering properties. The gasification biochar used for this study was a waste biochar produced as a byproduct of gasification at a lumber mill. The feed stock for this material was the residual pine material from the plant. The biochar was separated into two sizes: coarse (passing sieve No. 8 and retained on sieve No. 20), and fine (passing sieve No. 20). Shear strength, swelling, compressibility, collapsibility, hydraulic conductivity, water retention, cation exchange capacity, pH, and microstructural characteristics were determined for the clay amended with 5%, 10%, and 20% gasification biochar. For the tested materials, the results indicated modest increases in the shear strength up to 10% biochar content for both the coarse and fine biochars. There was no significant reduction in the maximum swell pressure for the fine biochar until the 20% level, which corresponds to a greater than 50% reduction. The coarse biochar exhibited a more gradual reduction, with each increase in biochar content resulting in a decrease in the maximum swelling pressure with a maximum reduction of approximately 50%. Slightly increased compressibility and more brittle behavior were also noted with increased levels of biochar amendment. Higher levels of biochar addition noticeably increased the compression index with the greatest increase occurring for the coarse biochar. Minor increases in the soil’s pH and collapse potential were also observed. The cation exchange capacity of the material decreased with increases in biochar. Gasification biochars exhibit large variability in properties and characteristics depending upon the source and process used to produce the biochar. This study aimed to present a framework to evaluate the potential benefits of the reuse of gasification biochars for improving geotechnical proprieties of marginal soils for select applications such as nonstructural fills. For site-specific applications, depending on the local source of gasification biochar, running laboratory tests on site-specific materials are needed.

A hybrid ozonation-biofiltration approach is evaluated to understand the necessity and concentration of ozone dose in removing the micropollutant microcystin-LR (MC-LR). To simulate real polluted water, three levels of natural organic matter—1, 2, and $5\mathrm{mg}/\mathrm{L}$—and cyanobloom intensity—low, medium, and high—under ozone exposure times—C1: $0.8\mathrm{mg}\times \min /\mathrm{L}$ and C2: $1.6\mathrm{mg}\times \min /\mathrm{L}$—were studied (18 combinations in total). The feasibility of filter bioaugmentation (postozone treatment) using known MC-LR degraders Arthrobacter ramosus (Filter FA) and Bacillus sp. (Filter FB) is also discussed and compared with the feasibility of a noninoculated sand filter. Overall, the bioaugmented sand filters, FA and FB, enhanced filter performance by 19.5% and 10.5% for C1 samples and 6% and 2% for C2 samples, respectively, in terms of MC-LR removal. All three filters, including the control (FC), showed a negative correlation (FA: $-0.987$; FB: $-0.973$; FC: $-0.977$) between “residual ozone” and “MC-LR removal due to ozonation.” However, A. ramosus (Filter FA) showed strong resilience toward the residual ozone ($0.1–0.4\mathrm{mg}/\mathrm{L}$) and did not affect MC-LR removal due to filtration as much as it affected Filters FB and FC. Only Filter FA showed a significant difference ($p$-value: 0.047) between bloom condition and MC-LR removal that showed less removal of the latter at higher bloom intensity and vice versa. Statistical analysis, too, suggested a strong influence of natural organic matter (NOM) on filter performance for MC-LR removal. Also, protein phosphatase inhibition assay (PPIA) toxicity showed less toxic by-product formation when native bacteria were co-cultured and inoculated with A. ramosus and Bacillus sp.) in a sand filter. Hence, combined ozonation-biofilter treatment using co-inoculation may simplify (eco)toxicological and biotransformation research. This will enable the study of diverse contaminants under other environmental parameters.

To explore the effects of some operating conditions on NO removal efficiency in a packed tower, the denitration process was simulated in a laboratory-scale packed tower using an ammonia solution containing Fe(II) ethylene diaminetetraacetic [Fe(II)EDTA]. The effects of pH, NO concentration, Fe(II)EDTA concentration, $({\mathrm{NH}}_4{)}_2{\mathrm{SO}}_3$ concentration, and ${\mathrm{SO}}_2$ concentration on denitration efficiency were studied. The experimental conditions to get the best denitration efficiency are as follows: pH of the absorbed solution is 6.5, liquid/gas ratio is $10\mathrm{L}/{\mathrm{m}}^3$, and the appropriate concentration of Fe(II)EDTA and $({\mathrm{NH}}_4{)}_2{\mathrm{SO}}_3$ is 0.03 and $0.1\mathrm{mol}/\mathrm{L}$, respectively. When the concentration of ${\mathrm{SO}}_2$ rises from 1,500 to ${\mathrm{2,000}\mathrm{mg}/\mathrm{m}}^3$, the removal efficiency of nitric oxide decreases slightly. The basic data obtained from results are in favor of the application of industrial desulfurization and denitration.

Few studies have been published on three-dimensional (3D) hydrodynamic and water quality modeling of a wetland with extensive data sets for model calibration and verification. Wetland plants include submerged aquatic vegetation (SAV) and emergent aquatic vegetation (EAV). A major difference between SAV and EAV is that SAV resides primarily in the bottom layer of the water column, whereas EAV extends through the entire water column. In a SAV area, the surface velocity can be very different from the bottom velocity. In this study, the Lake Okeechobee Environmental Model for Constructed Wetland (LOEM-CW) is enhanced to simulate hydrodynamic and water quality processes in the Everglades Stormwater Treatment Area 2 (STA-2) in Florida. The 3D LOEM-CW is applied to $2\mathrm{years}$ (January 1, 2015–December 31, 2016) of extensive data sets for model calibration and verification. The 3D LOEM-CW was capable of resolving the vertical profiles of vegetation in wetland so that stratifications of key parameters were simulated realistically. The model is also applied to support STA operation and management.

Data-driven membrane prediction models including multiple linear regression and neural network have been widely applied to analyze reveal rejection interactions between various compounds and membranes. While the random forest algorithm is an ensemble learning method widely applied in science, engineering, and many other fields, few studies apply a random forest model for predicting membrane rejection. Thus, this study proposes a random forest model for predicting nanofiltration/reverse-osmosis-membrane rejection of emerging organic contaminants. The original membrane rejection dataset was collected from multiple studies and included 701 points of 84 organic compounds. This study (1) examined prediction performance between random forest and neural network models; (2) compared identified important features from random forest feature importance, principal component analysis, and Pearson correlation coefficient; and (3) analyzed hyper-parameter tuning process and results between random forest and neural network. The findings of this study suggest that random forest is feasible for modeling membrane rejection prediction (determination $\mathrm{coefficient}\ge 0.9$). The integrated function of feature importance can reliably identify important features, and the random forest model required less efforts for turning parameters than the neural network model.

This test represents a water quality improvement exemplary project in relation to a tributary section of the Maozhou River located within the Bao’an District, Shenzhen, China. It uses in situ pollution control, aeration, and biofilm combined technologies to treat black and odorous water in situ. Three kinds of aeration equipment are used in the test project: a micronano aerator, push-flow aerator, and jet aerator. The operation results show that the micronano aerator is better than the push-flow aerator, and the push-flow aerator is better than the jet aerator. Three biological fillers were used in the test project: carbon fiber grass, AquaMats ecobase, and biological ribbon. The operation results show that the carbon fiber grass is better than the AquaMats ecobase, and the AquaMats ecobase is better than the biological ribbon. After processing, it was found out that the later transparency, dissolved oxygen (DO), oxidation-reduction potential (ORP), Ammonia nitrogen content index (${\mathrm{NH}}_3\text{-}\mathrm{N}$), dichromate oxidizability (${\mathrm{COD}}_{\mathrm{cr}}$), and biochemical oxygen demand (${\mathrm{BOD}}_5$) all could comply with the requirements of treatment, indicating that the combined technology is practically viable. The combination technology can provide valuable reference for the treatment of urban black and odorous water.

Untreated wastewater samples were collected from the Great Lakes Water Authority (GLWA) Water Resource Recovery Facility (WRRF) located in southeast Michigan between April 8 and May 26, 2020. The WRRF is the largest single-site wastewater treatment facility in the US, and it receives wastewater from its service area via three main interceptors: Detroit River Interceptor (DRI), North Interceptor-East Arm (NI-EA), and Oakwood-Northwest-Wayne County Interceptor (O-NWI). A total of 54 untreated wastewater samples were collected (18 per interceptor) at the point of intake into the WRRF. Viruses were isolated from wastewater using electropositive NanoCeram column filters (Argonide, Sanford, Florida). For each sample, an average of 45 L of wastewater was passed through NanoCeram electropositive cartridge filters at a rate of no more than $11.3\mathrm{L}/\mathrm{m}$. Viruses were eluted and concentrated and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) concentrations were quantified with reverse transcription quantitative polymerase chain reaction (RT-qPCR). SARS-CoV-2 was detected in 100% of samples, and measured concentrations were in the range of ${10}^4$–${10}^5$ genomic copies/L. Quantification of concentrations of human viruses, such as SARS-CoV-2, in wastewater is a critical first step in the development of wastewater-based epidemiology predictive methods. However, accurate prediction involves the incorporation of multiple other measurements, data, and processes, such as the estimation of fate and detention times of viruses in the sewer collection network, estimation of contributing population, incorporation of disease characteristics based on anthropometric data, and others. A viral disease prediction model (Viral PD) that incorporates all these other inputs is currently being developed for COVID-19 in Detroit, Michigan.