Journal of Environmental Engineering

Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to calculate, analyze, and visualize fluid (liquids, gases, and dissolved gases) flows. This document provides general introductions to best practices for CFD modeling in water infrastructure for practitioners, particularly those new to CFD modeling, which is becoming a widely used tool in the design and retrofitting of water, wastewater, and stormwater infrastructure. The method serves as an alternative, or complement, to physical modeling. In recent years, CFD has often been used in evaluating and troubleshooting existing water systems as well as improving future designs. As with the applications in other fields, the popularity of CFD in the water industry has been propelled by a multitude of factors including, but not limited to, the maturity achieved by CFD techniques, the development of stable and reliable numerical schemes, and the ever-improving computer-aided design (CAD) and meshing technologies for real-world complex geometries. This has been accompanied by many commercial and open-source CFD packages that can be run on increasingly more powerful computing hardware. Despite the visible progress in the application of CFD in water infrastructure projects achieved to date, there are still many challenges that hinder the widespread use of CFD techniques in water treatment design. Perhaps more important is that many of these challenges may result in misuse of the tool with dire consequences. It is imperative that CFD practitioners appropriately apply this tool without overpromising capability or accuracy and that reviewers of CFD model results know what to look for in ensuring proper methods have been applied and that results are representative of reality.

The degradation of azo dyes by conventional methods has proven ineffective due to their complex structure and synthetic nature. Bioremediation of azo dye containing textile wastewater requires an appropriate selection of potential strains to address its potential hazards. This study focuses on the biodegradation of azo dyes containing textile wastewater by isolating halotolerant bacterial strains from marine coastal soil. The rapid degradation of model dye Mordant Yellow 10 (MY10) was monitored spectrophotometrically and it was found that decolorization of MY10 by isolated strains Bacillus firmus (BA01), Pseudomonas aeroginosa (BRPO3), and Bacillus cereus (BRPO4) and mixed consortium CMBS follows zero-, second-, first-, and one-and-a-half-order kinetics, respectively. Through the batch kinetic analysis of MY10 degradation, it was observed that bacterial strain Pseudomonas aeroginosa BRPO3 was more effective with reaction rate constant and half-life as $\mathrm{1,024}\pm 213\times {10}^{-2}{\mathrm{mM}}^{-1}{\mathrm{day}}^{-1}$ and $0.3\pm 0.1\mathrm{day}$, respectively. Further kinetic analysis using BRPO3 helps describe that initial dye and glucose concentration were the driving forces of the dye degradation reaction and thus were used to construct kinetic rate equation. Using a stepwise protocol, this kinetic model was applied to calculate the design parameters including optimal height and working volume of an upflow anaerobic packed bed (UAPB) reactor as 0.95 m and 4.78 L, respectively, for 85% dye conversion. Design was validated by evaluating the performance of the newly fabricated UAPB reactor for treatment of simulated wastewater containing MY10 and real textile wastewater. Complete dye removal and 94.5% total organic carbon (TOC) reduction were observed with simulated wastewater, whereas in real textile effluent 82.5% dye removal and 89% TOC reduction were achieved. Thus, the predicted results corresponded satisfactorily with the experimental data in both wastewater treatments. This study highlights the usefulness of analyzing biodegradation kinetics to improve both the construction of microbial consortia and the development of reactors for wastewater treatments in the context of bioeconomy.

In this work, a composite adsorbent (modified poly-o-phenylene aquatic plant cellulose; MPP-AC) was prepared by using aminated mesoporous material as the carrier, aquatic cellulose as the dopant, and supporting poly-o-phenylenediamine. The adsorption study indicates that the adsorbent can reach a maximum saturation adsorption capacity of $231.25\mathrm{mg}/\mathrm{g}$. The data fit analysis reveals that the adsorption of Hg(II) by MPP-AC is consistent with a quasi-second-order kinetic model and followed the Langmuir adsorption isotherm model. The whole adsorption process is a heat absorption process that proceeds spontaneously. Interfering ion experiments show that coexisting cations have almost no competitive effect on the removal of Hg(II), indicating that the adsorbent has good selectivity for Hg(II) adsorption. After five cycles of adsorbent regeneration experiments, the adsorption capacity of MPP-AC can reach $210.27\mathrm{mg}/\mathrm{g}$, indicating that the adsorbent has good regeneration performance. The composite can be used as an effective, economical, and environmentally friendly potential adsorbent for the adsorption of mercury ions.

The Colorado River supplies water to seven southwestern states and Mexico. It is one of the most stressed river systems in the US. To address sustainability in the Lower Colorado River Basin (LCRB), the US Bureau of Reclamation (USBR) organized discussion of river operations and diversions among the LCRB states, eventually leading to the 2007 Interim Guidelines (2007-IG) and then to a revised river management structure, the 2019 Drought Contingency Plan (DCP). Among other features, the DCP increased the severity of reductions, or shortages, in annual water deliveries to the LCRB states (California, Arizona, and Nevada) and Mexico that are triggered by low year-end water levels in Lake Mead. Shortage measures were designed to mitigate the effects of long-term southwestern drought on reservoir levels, perhaps avoiding the worst outcomes for regional water supply while maintaining the energy-generating capability of the Colorado River system. The objective of this study was to evaluate water supply reliability in the LCRB with and without DCP measures and with and without anticipated climate effects. Four combinations of hydrological conditions and management strategies were analyzed. The results show that both 2007-IG and DCP measures will reduce the most severe shortages in Colorado River Water (CRW) supply to the LCRB states and Mexico under historical hydrologic conditions. Neither set of regulating measures insulates the LCRB against drought with anticipated climate change. However, the most distressing low-water projections are predicted to be less frequent and severe with DCP measures in place. The methods used to project the impacts attributable to climate change and the DCP on LCRB water deliveries can be used to anticipate the effects of alternative river management provisions now under consideration for drought mitigation.

The present investigation applies the stabilization/solidification technique for lead (Pb)-contaminated soil remediation utilizing an organic binder to negate the environmental consequences caused by inorganic binders such as cement. This research synthesized novel biochar by slow pyrolysis of moringa seed cake or de-oiled cake (waste generated after oil recovery) and tested its physicochemical characteristics, which revealed that it possesses a high pH and abundant surface functional groups that can act as potential adsorption sites for lead. Furthermore, the effects of biochar content (0% to 10% w/w) and curing time on the stabilization of soil contaminated with Pb at a concentration of $\mathrm{5,000}\mathrm{mg}/\mathrm{kg}$ were evaluated. The toxicity characteristic leaching test showed that treatment with 10% w/w biochar and 28 days of curing reduced Pb leachability to regulatory limits with over 89% immobilization efficiency. Moreover, the soil strength and the pH increased steadily with the biochar content and curing time while maintaining stability after 56 to 90 days of curing. Microstructural characterization revealed the underlying mechanisms in effectively stabilizing lead in soil, including precipitation, surface complexation with functional groups (C═O, O═C─ O), and lead encapsulation in calcium silicate hydrates (C─ S─ H).

Abstract

In this study, two combined processes of coagulation sedimentation-NaClO disinfection and coagulation sedimentation-ultrafiltration (UF)-NaClO disinfection are used as advanced treatment processes to explore the removal effect and mechanism of the combined processes on Legionella, Pseudomonas aeruginosa, Mycobacterium avium, and Escherichia coli in the secondary effluent. In addition, reclaimed water was reused in the landscape as an evaluation scenario, Monte Carlo simulation of the health risk of opportunistic pathogens in process effluent was carried out, and the microbiological safety of the two processes was evaluated. The results showed that the combined process of coagulation sedimentation-UF-NaClO has a good removal effect on Legionella, Pseudomonas aeruginosa, Mycobacterium avium, and Escherichia coli, and the removal rates are 99.8%, 98.6%, 99.4%, and 99.1%, respectively. There is a significant positive correlation between the concentration of Escherichia coli in the secondary effluent and the three opportunistic pathogens, but the correlation between the concentration of Escherichia coli in the effluent and the three opportunistic pathogens is no longer significant after the two combination processes. The three opportunistic pathogens has the lowest single-exposure infection probability after secondary effluent coagulation sedimentation-UF-NaClO disinfection and reuse for urban landscape leisure activities. The safety rate for human health may range from 70.9% to 100%.

Practical Applications

Reclaimed water reuse is an important way to alleviate the current water crisis. Common deep-treatment technologies include coagulation and sedimentation, filtration, activated carbon adsorption, disinfection, and so on. Using secondary effluent from municipal wastewater treatment plants as the treatment target, the researchers studied the reclaimed water treatment process through simulation tests. The researchers examined the correlation between opportunistic pathogens and E. coli. Comparing the traditional filtration process and ultrafiltration in terms of engineering and construction benefits, although ultrafiltration has a higher cost per unit of water volume, it has a smaller footprint, the advantage in land cost can completely offset the disadvantage in construction cost, and the effluent water quality situation is also improved compared with the traditional filtration process. In addition, in order to ensure the microbiological safety of reclaimed water reuse and landscape water, it is necessary to evaluate the risk to human health caused by opportunistic pathogens in secondary effluent and effluent from different deep-treatment processes using risk assessment techniques, and to propose corresponding safety assurance techniques and processes. Therefore, ultrafiltration is feasible as a treatment unit for deep treatment and can be used as a reference basis for practical applications.

The high content of silicon and aluminum present in the thermal desorption residue of oil-based drilling cuttings (ODCR) makes it potentially suitable for use in subgrade materials. The main components of ODCR are akin to solid wastes such as slag, which can replace the fine aggregate of concrete. Cement, fly ash, additive (LG), and ODCR were used to prepare the subgrade in this investigation. LG is a newly formulated supplemental gel material. According to the Box–Behnken design of response surface method, the influence of raw materials formula on unconfined compressive strength (UCS) of the subgrade and the interaction among raw materials were explored. The hydration reaction mechanism was analyzed by X-ray diffraction and scanning electron microscope. In addition, the toxicity characteristic leaching procedure method (TCLP) was used for toxic leaching experiments on ODCR. The results showed that the UCS of the subgrade prepared with 10.64% cement, 14.97% fly ash, and 3.74% LG reached 4.61 MPa. This subgrade complied with the requirements of UCS to achieve 3–5 MPa in the standard, JTG E51-2009. The LG promoted the formation of hydration product calcium silicate hydrate and aluminum silicate hydrate gels, filled the pore of the specimen, and increased its UCS. Moreover, the leaching toxicity of ODCR met China standard, GB 5085.3-2007.

To investigate the effects of different structural parameters in the degradation of $o$-Dichlorobenzene ($o$-DCB) by dielectric barrier discharge nonthermal plasma (DBD-NTP) and to explore the optimal reactor structural parameters, experimental investigations were carried out using plasma reactors of different structures. The effects of single and double dielectric, different high-voltage electrode positions, different dielectric thicknesses, different discharge gaps and different discharge lengths on the degradation efficiency, carbon monoxide and carbon dioxide selectivity, carbon balance, and ozone of $o$-DCB were investigated in the reactor. The results show that single dielectric, external high-voltage electrode and lower dielectric thickness, discharge gap, and longer discharge length favor ozone control and improve $o$-DCB degradation and carbon monoxide ${\mathrm{CO}}_2$ selectivity as well as carbon balance.

Abstract

A common problem in laboratory-scale membrane research is that the testing methods in the laboratory are often quite different than industrial applications due to the limitations of manual experimental setups. Here, an automated membrane filtration apparatus was built in the lab to solve this problem by allowing long-term filtration, frequent backwash and clean-in-place (CIP), and high-accuracy operation. The filtration system achieves different cleaning strategies for both theoretical research and practical water and wastewater scale-up experiments. The embedded control algorithms achieve operational accuracy in terms of maintaining flux or transmembrane pressure (TMP) at their desired set points. A flux-step function enables operators to measure critical flux automatically. The filtration system handles a variety of microfiltration and ultrafiltration membranes in crossflow or dead-end mode with backwash integration, CIP capability, and aeration scouring. Synthetic and raw rendering wastewater were applied to test the apparatus in the lab and in the field, respectively. The control algorithms successfully dampened oscillations using custom calibration curves. Three backwash-CIP strategies were tested with both wastewater types. The first was time-triggered backwash and cycle number–triggered CIP, which resulted in stable and reliable operation but required close operator control and thus was not fully automated. The second strategy was time-triggered backwash with TMP-triggered CIP, which responded quickly to water quality fluctuations and achieved full automation, but the TMP target had to be carefully set to enhance the efficiency of CIP. The third strategy was target–TMP backwash with duration-triggered CIP, which can achieve the most advanced and flexible filtration system, though setting up this level of automation complexity in the field was challenging. Both backwash and CIP frequencies responded to real-time performance automatically. Ultimately, the automated lab-scale filtration apparatus operated similarly to full-scale systems, which should help fill the gap between laboratory research and scale-up of industrial applications.

Practical Applications

Laboratory membrane filtration research is usually different than industrial applications because lab workers are limited in their ability to perform all the steps that are done at full scale. An automated filtration system can solve the problem by performing continuous monitoring and control without user intervention. This paper provides detailed information about building and operating an automated filtration apparatus. The apparatus can perform experiments in the lab or the field where water quality fluctuates. All the important steps are included automatically: filtration, backwash, and CIP. This article discusses how to adjust the timing and the triggering of each step for optimal performance. Other functions, like an algorithm to easily determine critical flux, are also described. This should allow other researchers to build similar systems, thus making more laboratory work directly relevant to full-scale applications.

Yeast production wastewater is an industrial wastewater with a high organic pollutant content, and it has different adverse effects on the environment as untreated discharge. To treat this kind of wastewater with a high chemical oxygen demand (COD), advanced wastewater treatment technologies have to be used and evaluated with economic parameters for their applicability. The objective of the study was the technoeconomic optimization of ultraviolet Fenton oxidation (UV/FO) and ultraviolet electrochemical Fenton oxidation (UV/EFO) processes as a subsection of hybrid advanced-oxidation processes (AOPs) for the effective degradation of COD from ultrafiltration filtrate wastewaters, a byprocess of yeast production. In optimization studies, the influence of operating parameters such as pH, current density $(\mathrm{CD})/{\mathrm{Fe}}^{2+}$ concentration, ${\mathrm{H}}_2{\mathrm{O}}_2$ concentration, and economic parameters such as sludge disposal, chemical cost, electrode cost, energy cost, and total operating cost was investigated. A double-criteria optimization option has been used to maximize the COD removal efficiency and minimize the total operating cost of the processes by the response surface methodology (RSM), and parametric effects of main factors on the processes were evaluated in a detail. The optimal conditions using the UV/FO process were determined to be an initial pH of 3, ${\mathrm{Fe}}^{2+}$ concentration of $3.52\mathrm{g}/\mathrm{L}$, and ${\mathrm{H}}_2{\mathrm{O}}_2$ concentration of $79.76\mathrm{g}/\mathrm{L}$, in which the COD removal was 99.96% and the total organic carbon (TOC) removal was 76%, with a total operating cost of $16.96\$/{\mathrm{m}}^3$ ($1.73\$/\mathrm{kg}{\mathrm{COD}}_{\mathrm{rem}}$). In the UV/EFO process, the optimum conditions were observed to be an initial pH of 3.07, current density of $5.68\mathrm{mA}/{\mathrm{cm}}^2$, and ${\mathrm{H}}_2{\mathrm{O}}_2$ concentration of $180.63\mathrm{g}/\mathrm{L}$, in which COD removal was 99% and TOC removal was 81%, with a total operating cost of $13.00\$/{\mathrm{m}}^3$ ($1.34\$/\mathrm{kg}{\mathrm{COD}}_{\mathrm{rem}}$). Based on the obtained results, it was found that UV/FO and UV/EFO processes resulted in a considerable amount of COD removal. Almost for the same COD removal efficiency, the UV/EFO process was observed to have a lower cost in terms of sludge disposal and the chemicals used. The UV/EFO process is an effective technology improving the wastewater quality for potential reuse and a cost-effective approach.

Anaerobic digestion is the most prevalent stabilization method used in treating waste activated sludge. However, the digested sludge produced has always been difficult to dehydrate. In this study, mesophilic anaerobic digested sludge and thermophilic anaerobic digested sludge were used to compare the dewatering capacity of two chemical coagulants: high-performance polyaluminum chloride (HPAC) and ${\mathrm{FeCl}}_3$. For mesophilic anaerobic digestion, 5% g/g total suspended solids (TSS) was the optimal dose of ${\mathrm{FeCl}}_3$ and HPAC to improve dewaterability. In addition, HPAC was superior to ferric chloride in the removal of loosely bound extracellular polymeric substances (LB-EPS) and tightly bound extracellular polymeric substances (TB-EPS). For thermophilic anaerobic sludge, HPAC is more effective compared with ${\mathrm{FeCl}}_3$ in improving the dewaterability. ${\mathrm{FeCl}}_3$ could effectively remove TB-EPS, while HPAC had better removal efficiency on soluble extracellular polymeric substances (S-EPS) and LB-EPS. Both chemical coagulants have greater potential to degrade EPS during thermophilic anaerobic digestion sludge treatment. The results of the supernatants characterization after conditioning illustrated that ${\mathrm{FeCl}}_3$ and HPAC have similar removal efficiency on organic matter, but HPAC could remove additional small molecular weight compounds, particularly when conditioning with the thermophilic anaerobic sludge; however, there was no apparent changes when using ${\mathrm{FeCl}}_3$.

Traditional incinerators achieve the thermal requirements through heat transfer and heat radiation. However, the early recovery of flue gas preheats the air and yields nitrogen oxide (NOx) to rise in the combustion of overoxygen. The operation of an incinerator inevitably implies the release of greenhouse gases and emissions of NOx harmful to the human health. The administrator of one laboratory incinerator in Taiwan sought to optimize the operation conditions such as temperature or oxygen level of the combustion products within the combustion chamber to minimize the release of pollutants and maximize the efficiency of combustion. In this phase, air-fuel ratio control and air volume control are regarded as the first priority. A numerical model of the laboratory-scale plant in southern Taiwan is established by using enhanced wall treatment and coupling the thermochemical conversion of volatile waste to the gaseous combustion of the released syngas. The model allows users to characterize the temperature and retention time of the combustion products for the verification of the fulfillment of the existing regulation for NOx and oxygen level in incineration plants. It shows trade-off relationship between combustion efficiency of fuel and emissions (NOx and CO) in surveying cases of air-fuel ratio (AFR) ranges from $1.5:1$ to $14.4:1$ according to numerical results. Increasing the air volume enhances this trend. In this study, it shows the lowest emissions of NOx in case of $\mathrm{AFR}=1.5:1$, but worse combustion efficiency. Meanwhile, to increase the air volume by 1.15 times suppress most CO and about 28% NOx, but increases by 6% the residual fuel. The averaged distribution of retention time of particles in this study ranged from 30 to 50 s, and is provided for further improvement of geometry in the next phase.

Abstract

In this study, an integrated process is employed in a wastewater treatment plant (WWTP) with a capacity of $200{\mathrm{m}}^3/\mathrm{day}$ for treatment of highly toxic wastewater from different industrial effluents, including electronic manufacturing, metal electroplating, painting process, waste gasoline. The wastewater was characterized by the chemical oxygen demand (COD) of about $\mathrm{30,000}\mathrm{mg}/\mathrm{L}$ and various heavy metals with a wide range of concentration, which makes the wastewater complicated and recalcitrant as compared to domestic and municipal wastewater. The study was divided into 2 phases (i.e., lab-based experiments and on-site operation) with three treatment steps including Fenton-related advanced oxidation process (AOP), coagulation, and spiral wound reverse osmosis (SPRO) filtration. For the Fenton process, the effective conditions were determined experimentally as reaction time of 60 minutes with pH of 3.0, ${\mathrm{H}}_2{\mathrm{O}}_{2}600\mathrm{mg}/\mathrm{L}$, and ${\mathrm{Fe}}^{2+}$ of $200\mathrm{mg}/\mathrm{L}$. For the coagulation, following parameters are effective values: pH of 7.5, coagulant as poly aluminum chloride (PAC) of $700\mathrm{mg}/\mathrm{L}$, and polymer of $15\mathrm{mg}/\mathrm{L}$. During 5 months of operation at WWTP under defined effective conditions, high COD removal efficiency of $>99\%$ was obtained. The concentration of heavy metals in the effluent satisfied the allowable discharge levels. In addition, a high recovery rate of water permeates (i.e., 80%–90%) can be obtained from the SPRO system. The treated water meets the national discharge standard indicating the potential for wastewater reuse. This study successfully demonstrates the practicability of the integrated process as Fenton—coagulation and reverse osmosis (RO) membrane to treat wastewater containing recalcitrant pollutants with high concentrations, which promotes the applicability of advanced technologies for WWTP in Vietnam. It also provides useful information and valuable data for the WWTP owner during the actual operation to obtain a stable performance and economic efficiency.

Practical Applications

The study determined effective conditions for operation of a highly toxic wastewater treatment plant with capacity of $200{\mathrm{m}}^3/\mathrm{day}$ located in Bac Ninh province, Vietnam. The treatment process integrated advanced oxidation as Fenton and coagulation followed by RO membrane filtration to remove recalcitrant pollutants from different industrial effluents including electronic manufacturing, metal electroplating, painting process, waste gasoline. This integrated and advanced technology has not been examined much in Vietnam and the practical applicability is thus limited. The investigation employed real wastewater collected at the treatment plant to find out the actual treatment efficiency. The results and findings obtained in this study demonstrated the excellent performance of treatment process, which encourage the replication of the technology. The wastewater after treatment satisfied the current national discharged standards and was proposed for reuse due to high-quality water output. The study also helps the investor to reduce the operational cost which mainly relied on the chemicals and energy consumption.

This study focused on the mixing of a solute, assumed to be conservative, introduced to one arm of an afterbay reservoir, between Keswick and Shasta Dams on the Sacramento River near Redding, California. Rhodamine water tracer (WT) dye served as the solute in a field experiment, and was introduced over 4.5 h and monitored for 4 days by sondes moored in the reservoir. The scenario was modeled numerically using the Delft3D flexible mesh (FM) hydrodynamic and mixing model, with measured inflows, outflows, water level, water temperatures, and bathymetry as input. Manning’s $n$ and horizontal eddy viscosity served as the (constant) model calibration parameters, and each was adjusted an order of magnitude below the default values to force observed and modeled dye hydrographs to match in arrival time and duration. The low friction factor was concluded to be due to a combination of low flow speeds coupled with energy dissipation inherent to the model. The model and surface drifters equipped with dual-frequency Global Navigation Satellite System equipment revealed velocities in the $1–5\mathrm{cm}/\mathrm{s}$ range in much of the domain during the experiment. Simple analytical expressions were shown to be useful for estimating distance to full cross-sectional mixing, steady-state concentrations, and time to reach them, but the numerical model is required for investigation of the approach to steady state, and at locations where flows intersect. Time to steady-state concentrations was 1.5–13 days for 10 simulations that spanned a wide range of inflow conditions. Model sensitivity tests suggest that wind and heat fluxes were not important during the field study, but simulations of a summer scenario with small inflows of cold water upstream in warm weather should consider water temperature. Both field observations and numerical model results showed inflow to one arm of the reservoir reaching full cross-sectional mixing before plunging below the water surface near the intersection of this arm with the reservoir’s main stem. Model results are being used to guide management decisions related to inflows to the reservoir from a relic mining site that is also a USEPA Superfund site.

The development of industry has caused metal pollution of aquatic ecosystems and water deterioration worldwide. Therefore, environmentally friendly strategies for industrial wastewater treatment are needed. In this study, constructed wetlands (CWs) were planted with Schoenoplectus californicus in a culture medium with different concentrations of Cu, Pb, and Zn. The aims of this work were to evaluate the ability of S. californicus to accumulate Cu, Pb, and Zn and its physiological response to metal exposure, and assess the wastewater treatment performance of the CW systems. The accumulation of Cu, Pb, and Zn in the shoot and root of the emergent aquatic plant depended on the metal concentration during the 28 days of exposure, except for Pb in shoots. The bioconcentration factors of Cu ($46.7\pm 10.8$) and Zn ($896\pm 317$) were highest in the treatment with moderate levels of metals (T-2), whereas for Pb ($57.4\pm 15.9$), the maximum bioconcentration factor was recorded in the treatment with the highest metal levels (T-3). Metal translocation from root to shoot reached values greater than 1 for Cu, but were lower for Pb and Zn because accumulation occurred predominantly in the root. In general, the removal efficiency of the CW systems was higher than 90% for Pb and Zn, and higher than 80% for Cu. Furthermore, Cu, Pb, and Zn bioaccumulation in S. californicus did not reflect toxicological damage to physiological parameters, such as the formation of products of lipid membrane peroxidation. The results showed that the exposure to relatively high metal concentrations in the CWs did not affect the survival of the species. Considering the capacity of S. californicus to tolerate and accumulate Pb, Zn, and Cu, this species can be used as a phytoextractor in wastewater treatment in CW systems.

US small islands are at increased risk of water insecurity due to climate change compared to mainland communities. Utilizing multiple water sources can provide improved climate change resilience but may increase a household’s water management burden and risk of exposure to poorer quality water. In the US Virgin Islands, the majority of households rely on roof-harvested rainwater while supplementing with desalinated water provided by trucks or the municipal system. Given this potential managerial burden, Love City Strong conducted a 2.5-year water management pilot program to provide participants with an ultraviolet (UV) water treatment system, replacement parts, operational training, and water testing for one year. Preliminary data were reported previously; however, the program was completed in October 2021 having served 66 households and provided $n=697$ post-treatment water tests. The final data suggested 7.7% of post-treatment tap samples (5.8% without outliers) and 66% of cistern samples had detectable levels of E. coli. This data provides further evidence of the success of this water management pilot program and, along with previously published program component data, can be used to craft an island- or territory-wide water treatment and management program to support household access to potable water.

With the increase in the chemical oxygen demand (COD) of the influent and the organic/hydraulic loading rate (OLR/HLR), the treatment efficiency of the vermifiltration (VF) process decreases. Also, the treatment performance of the VF process varies with the type of wastewater, even if all the other operating conditions remain the same. To date, the inhibitory effects of wastewater, e.g., its composition, concentration, and OLR/HLR, on earthworms (EWs) and VF’s treatment efficacy have been completely overlooked. Herein, such inhibitory effects on the survival, growth, and reproduction of the EWs have been investigated using real brewery, dairy, domestic, and diluted brewery wastewater. The acute and chronic tests were performed in vertical subsurface flow reactors in accordance with the guidelines with some modifications. Results showed that 50% mortality of EWs occurred within 11–21, 16–33, 21–41, and 24–48 days for brewery, diluted brewery, dairy, and domestic wastewater, respectively, at the HLR of $8–4{\mathrm{m}}^3{\mathrm{m}}^{-2}{\mathrm{day}}^{-1}$. For each wastewater, the maximum growth of EWs was observed at the lowest tested HLR ($4{\mathrm{m}}^3{\mathrm{m}}^{-2}{\mathrm{day}}^{-1}$). Domestic sewage ensured the highest number of juvenile (20–38 nos. ${\mathrm{EW}}^{-1}$) and cocoon production (10–15 nos. ${\mathrm{EW}}^{-1}$), followed by dairy (juveniles: 7–21; cocoons: 5–10), diluted brewery (juveniles: 4–15; cocoons: 2–9), and brewery wastewater (juveniles: 2–12; cocoons: 2–7), with the HLR and OLR having a negative impact on the same. Therefore, brewery wastewater had the highest biological inhibition on survival and biological activities of the EWs, whereas domestic sewage had the least. The dilution given to brewery wastewater reduced the extent of the inhibitory effects imposed on the survival, growth, and reproduction of EWs. Results of this study indicated that the VF technology is more suitable for treating domestic sewage, can treat dairy wastewater substantially, and can treat brewery wastewater, but appropriate pretreatment (such as bioaugmentation or dilution) may be necessary.