Removal Of Pathogens Research Articles

Changes of putative pathogenic species within the water bacterial community in large-scale drinking water treatment and distribution systems

Although the management of microbes in drinking water is of paramount importance for public health, there remain challenges in comprehensively examining pathogenic bacteria in the water supply system at the species level. In this study, high-throughput sequencing of nearly full-length 16S rRNA genes was performed to investigate the changes of the water bacterial community in three large-scale drinking water treatment plants (DWTPs) and their corresponding distribution systems during winter and summer. Our findings revealed significant differences in the bacterial community structure between winter and summer water samples for each DWTP and its distribution management area (DMA). In the groundwater-fed DWTP, selective enrichment of mycobacterial species was observed in both seasons, and the subsequent DMA also exhibited strong selection for specific mycobacterial species. In one of the surface water-fed DWTPs, certain Legionella species present in the source water in winter were selectively enriched in the bacterial community after pre-oxidation, although they were susceptible to the subsequent purification steps. A variety of putative pathogenic species (n = 83) were identified based on our pathogen identification pipeline, with the dominant species representing opportunistic pathogens commonly found in water supply systems. While pathogen removal primarily occurred during the purification processes of DWTPs, especially for surface water-fed plants, the relative abundance of pathogenic bacteria in the DMA water flora was lower than that in the DWTP effluent flora, indicating a diminished competitiveness of pathogens within the DMA ecosystem.

Application of algae in wastewater treatment

Nowadays, water contamination has become one of the most significant environmental issues. The creation and use of algal biotechnology with less investment, good effect and low operating cost has garnered a lot of attention. With the ongoing development of numerous new water treatment technologies, low-cost and effective ecological governance systems have been created quickly. Its purpose is to improve the sewage purification process by improving the inorganic process of organic matter, accelerating the expansion and multiplication of microorganisms, enhancing the metabolic function of microorganisms, and promoting the proliferation of microorganisms. In this article, the removal of nitrogen, phosphorus, heavy metals, antibiotics, pathogens and pesticides by algae was introduced. Additionally, typical algae systems including immobilized algae systems, algal-bacterial symbiotic systems and combination high-rate algae pond systems used in sewage treatment and the limitations and prospects of algae technology were discussed. Algal wastewater treatment is more effective in removing nitrogen and phosphorus than conventional activated sludge processes. Aquaculture wastewater, industrial drainage, municipal sewage, and other distinct forms of water treatment processes can all benefit from the simultaneous transformation and removal of nitrogen, phosphorus, sulfur, refractory organic matter, and heavy metals in sewage that is made possible by algae technology. Engineering techniques and technological advancement will be used to create high-efficiency microalgae wastewater treatment reactors, optimize conditions, increase the utilization efficiency of microalgae biological resources, and apply microalgae to wastewater treatment, which will have a significant impact on water quality and economy.

Exploration of Microalgae-Activated Sludge Growth Performance in Lab-Scale Photobioreactors under Outdoor Environmental Conditions for Wastewater Biotreatment

Increasing the volume of untreated and inadequately treated municipal wastewater undermines the circular economy potential of wastewater resources, particularly in low-income regions. This present study focused on and evaluated the performance of native microalgae-activated sludge (MAS) growth for tertiary treatment of anaerobically digested wastewater from an up-flow anaerobic sludge blanket (UASB) in an outdoor lab-scale photobioreactor (2.2 L). Three conditions with distinct MAS inoculum concentrations alongside three controls were operated in batch mode for 5 days hydraulic retention time (HRT) at 11.5:12.5 photo-hours. The MAS inoculum concentration influenced the treatment outcome. The best performance was observed when the MAS concentration was 0.10/0.20 g L−1, and the cell density was 1.60 × 107 cells mL−1, total biomass productivity of 0.10 g TSS L−1 d−1, total phosphorus uptake of 85.1%, and total nitrogen uptake of 66.1%. Logarithmic removal (Log-Re) of bacterial pathogens (water quality indicators) showed Log-Re 3.4 for total coliforms (1.37 × 102 CFU 100 mL−1) and 4.7 for Escherichia coli (0.00 × 100 CFU 100 mL−1). The results revealed optimum remediation performance and nutrient recovery potential with appropriate inoculum concentration, in admiration to advancing the science of circular economy.

2D Fluorinated Graphene Oxide (FGO)-Polyethyleneimine (PEI) Based 3D Porous Nanoplatform for Effective Removal of Forever Toxic Chemicals, Pharmaceutical Toxins, and Waterborne Pathogens from Environmental Water Samples.

Although water is essential for life, as per the United Nations, around 2 billion people in this world lack access to safely managed drinking water services at home. Herein we report the development of a two-dimensional (2D) fluorinated graphene oxide (FGO) and polyethylenimine (PEI) based three-dimensional (3D) porous nanoplatform for the effective removal of polyfluoroalkyl substances (PFAS), pharmaceutical toxins, and waterborne pathogens from contaminated water. Experimental data show that the FGO-PEI based nanoplatform has an estimated adsorption capacity (qm) of ∼219 mg g-1 for perfluorononanoic acid (PFNA) and can be used for 99% removal of several short- and long-chain PFAS. A comparative PFNA capturing study using different types of nanoplatforms indicates that the qm value is in the order FGO-PEI > FGO > GO-PEI, which indicates that fluorophilic, electrostatic, and hydrophobic interactions play important roles for the removal of PFAS. Reported data show that the FGO-PEI based nanoplatform has a capability for 100% removal of moxifloxacin antibiotics with an estimated qm of ∼299 mg g-1. Furthermore, because the pore size of the nanoplatform is much smaller than the size of pathogens, it has a capability for 100% removal of Salmonella and Escherichia coli from water. Moreover, reported data show around 96% removal of PFAS, pharmaceutical toxins, and pathogens simultaneously from spiked river, lake, and tap water samples using the nanoplatform.

Innovative Approaches to Poultry Processing Wastewater Treatment: The Stainless Steel Ultrafiltration Membrane as a Viable Option.

In pursuit of sustainability, we explored replacing conventional dissolved air floatation (DAF) in poultry processing wastewater (PPW) treatment with a precisely tuned 0.02 µm stainless-steel ultrafiltration (SSUF) membrane. SSUF is a robust, homogenously porous membrane with strong chemical resistance, ease of cleaning, and exceptional resistance to organic fouling. Unlike polymeric membranes, it can be regenerated multiple times, making it a cost-effective choice due to its compatibility with harsh chemical cleaning. The PPW used for the study was untreated wastewater from all processing units and post-initial screening. Our study revealed the SSUF membrane's exceptional efficiency at eliminating contaminants. It achieved an impressive removal rate of up to 99.9% for total suspended solids (TSS), oil, grease, E. coli, and coliform. Additionally, it displayed a notable reduction in chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total Kjeldahl nitrogen (TKN), up to 90%, 76%, and 76%, respectively. Our investigation further emphasized the SSUF membrane's ability in pathogen removal, affirming its capacity to effectively eradicate up to 99.99% of E. coli and coliform. The measured critical flux of the membrane was 48 Lm-2h-1 at 38 kPa pressure and 1.90 m/s cross-flow velocity. In summary, our study highlights the considerable potential of the SSUF membrane. Its robust performance treating PPW offers a promising avenue for reducing its environmental impact and advocating for sustainable wastewater management practices.

Ceramic Filters for the Efficient Removal of Azo Dyes and Pathogens in Water

Overcoming the scarcity of safe and sustainable drinking water, particularly in low-income countries, is one of the key challenges of the 21st century. In these countries, the cost of centralized water treatment facilities is prohibitive. This work examines the application of low-cost ceramic filters as point-of-use (POU) devices for the removal of methylene blue, o-toluidine blue, Staphylococcus aureus, and Staphylococcus typhi from contaminated water. The ceramic filters had typical kaolinite functional groups, making them suitable for the removal of dyes and pathogens. Surface charge measurements indicated strongly anionic filters, while thermal properties confirmed the carbonization of the biowaste additive leaving behind a porous kaolinite structure which subsequently dehydroxylated into meta kaolinite. In addition, morphological data showed heterogeneous filter surfaces. Increased biomass content improved the permeability, water adsorption, flow rate, and apparent porosity of the filter. The ceramic filter removed methylene blue (42.99–59.74%), o-toluidine (79.95–92.71%), Staphylococcus aureus (98–100%), and Staphylococcus typhi (75–100%). Overall, the study demonstrated the effectiveness of POU ceramic filters in removing organic pollutants in contaminated water while serving as disinfectants.

A light-driving magnetic nanocomposite based on Zn/Fe/Cu embedded in HKUST-1 applied for adsorption/degradation of Indigo carmine and pathogens

An environmentally friendly photocatalytic system (type-II heterojunction) is designed and utilized for rapid removal of Indigo carmine (IC) and pathogens from aqueous samples. This photocatalyst contains ZnFe2O4 magnetic NPs, CuO semiconductor, β-cyclodextrin (β-CD) charge transferor, and HKUST-1 light harvester. After the adsorption and photodegradation process, the nanocomposite was separated magnetically, and the supernatant was taken for the UV-Vis analysis. The maximum adsorption and photodegradation efficiency of 94.45% and 97.67% (pH = 5, in 35 min) were obtained under blue LED light (7.0 W) irradiation, due to the calculations based on UV-Vis spectrophotometer results. Simple preparation via a self-assembly route and facile separation through a superparamagnetic behavior (leading to great recovery) can be mentioned as the most brilliant excellence. Moreover, the photocatalytic performance of this magnetic nanocomposite was preserved after five recycle runs without any substantial reduction in photocatalytic activity. Also, employing a biopolymer, affordability, availability of the raw materials, good thermal stability, facile magnetic separation, simple operation, and high efficiency are upsides of the prepared nanocomposite, making it a superior photocatalyst to previous analogous systems. This nanocomposite (formulated as ZnFe2O4-CuO@β-CD)/HKUST-1) also exhibited antibacterial activity against Gram-positive and -negative strains. Based on BET (porosity) evaluations, the nanocomposite has rendered a surface area of 451.52 m2/g, which led to great adsorption results representing first-order and pseudo-second-order (Freundlich isotherm) kinetic models for the degradation and adsorption processes, respectively.

Inactivation of Escherichia Coli by mixed-valent nanoparticles in-situ generated during Fe electrocoagulation

Electrocoagulation (EC) is promising for the removal of chemical and microbial contaminants. Although the removal of pathogens from wastewater is efficient by conventional Fe-EC in the presence of dissolved oxygen (DO), the non-inactivated pathogens in the sediment still have a risk. Herein, the inactivation of Escherichia coli (E. coli) with the mixed-valent iron nanoparticles, magnetite and green rust (GR), in-situ generated from Fe-EC process in the absence of DO was investigated. The inactivation efficiency was significantly higher with magnetite (4.7 log cells) and GR (3.2 log cells) compared with FeOOH (0.7–1.7 log cells) generated at 50 mA in 10 min. The unstable in-situ generated magnetite with positive charges was prone to adsorb onto E. coli, damaging the cell membrane, inactivating the bacteria. The unstable in-situ generated GR was prone to coagulate with E. coli, delivering Fe2+ into the cell and inducing the generation of endogenous ROS, inactivating the bacteria. Fe-EC in the absence of DO was proved to be efficient for the inactivation of E. coli (4.2–4.3 log cells) in real wastewater. These findings identified the ignored inactivation effect and mechanism of E. coli with magnetite and GR generated in situ from Fe-EC process, which will provide theoretical support for real applications.

Assessment of pathogen removal efficiency of vertical flow constructed wetland treating septage

Septage refers to the semi-liquid waste material that accumulates in septic tanks and other onsite sanitation systems. It is composed of a complex mixture of human excreta, wastewater, and various solid particles. Septage is a potential source of water pollution owing to presence of high organic content, significant pathogen concentrations, and a range of nutrients like nitrogen and phosphorus. The harmful impacts of septage pollution poses significant risks to public health through the contamination of drinking water sources, eutrophication of water bodies and spread of water borne diseases. Conventional septage treatment technologies often face limitations such as high operational costs, energy requirements, and the need for extensive infrastructure. Therefore, with an aim to treat septage through an alternative cost effective and energy-efficient technology, a laboratory-scale constructed wetland (CW) system (0.99 m2) consisting of a sludge drying bed and a vertical flow wetland bed was utilized for the treatment of septage. The sludge drying bed and vertical flow beds were connected in series and filled with a combination of gravel with varying sizes (ranging from 5 to 40 mm) and washed sand. Canna indica plants were cultivated on both beds to facilitate phytoremediation process. The system was operated with intermittent dosing of 30 Ltrs of septage every day for 2 months. The HRT of the system was fixed at 48 h. The average inlet loads of Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), and Total Suspended Solids (TSS) were measured as 150 ± 65.7 g m−2 day−1, 713 ± 443.9 g m−2 day−1, and 309 ± 66.3 g m−2 day−1, respectively. After treatment, the final effluent had an average load of 6 g m−2 day−1 for BOD5, 15 g m−2 day−1 for COD, and 51 g m−2 day−1 for TSS, indicating that the CW system achieved an average removal efficiency of 88% for BOD, 87% for COD, and 65% for TSS. The average load of total coliforms and helminthes eggs in the influent was recorded as 4 × 108 Colony-Forming Units (CFU) m−2 day−1 and 3 × 107 eggs m−2 day−1, respectively. However, the CW system demonstrated significant effectiveness in reducing microbial contamination, with an average removal efficiency of 99% for both total coliforms and helminthes eggs. The vertical flow constructed wetland system, equipped with pretreatment by sludge drying bed, has proven to be efficient in treatment of septage.

Bibliometric analysis of electrochemical disinfection: current status and development trend from 2002 to 2022.

The removal of waterborne pathogens from water is critical in preventing the spread of waterborne diseases. Electrochemical methods have been extensively researched and implemented for disinfection, primarily owing to their simplicity, efficiency, and eco-friendliness. Thus, it is essential to conduct a review about the research progress and hotspots on this promising technique. In this paper, we provided a comprehensive bibliometric analysis to systematically study and analyze the current status, hotspots, and trends in electrochemical disinfection research from 2002 to 2022. This study analyzed literature related to electrochemical disinfection or electrochemical sterilization published in the Web of Science database from 2002 to 2022 using CiteSpace and Biblioshiny R language software packages. The analysis focused on the visualization and assessment of annual publication volume, discipline and journal distribution, collaborative networks, highly cited papers, and keywords to systematically understand the current status and trends of electrochemical disinfection. The results showed that between 2002 and 2022, 1171 publications related to electrochemical disinfection were published, with an exponential increase in the cumulative number of publications (y=17.518e0.2147x, R2= 0.9788). The publications covered 76 disciplines with many articles published in high-impact journals. However, the research power was characterized by a large number of scattered research efforts and insufficient cooperation, indicating the need for further innovative collaboration. The citation analysis and keyword analysis suggest that future development in this field may focus on optimizing electrode materials, investigating the disinfection performance of ·OH based systems, optimizing conditions for actual wastewater treatment, and reducing energy consumption to promote practical applications.

Dynamical analysis of an age-structured cholera transmission model on complex networks

Cholera is a water- and food-borne infectious disease caused by the bacterium Vibrio cholerae. In this paper, we present a novel modeling framework to investigate the effect of infection age on cholera transmission in a heterogeneous population. Our model is constructed on a system with infection age on complex networks, including both direct and indirect transmission routes and demographics. The basic reproduction number R0 is derived as the spectral radius of the next generation operator, and it is verified that R0 is a sharp threshold that determines whether cholera becomes extinct or not. Numerical simulations are performed to confirm the theoretical results. Furthermore, the sensitivity analysis of the basic reproduction number to the parameters suggests that the implementation of effective drug treatment for infected individuals and the timely removal of pathogens from contaminated water are beneficial to control the spread of cholera.

Assessment of total coliforms and E. coli removal in algae-based pond under tropical temperature in addition of carbon dioxide (CO2) and shading

The present work aimed to investigate the effects of adding CO2 to the treatment carried out by native microalgae in a raceway pond with high load sewage to remove E. coli and total coliforms, as well as to evaluate the influence of shading on the treatment system operated on a pilot scale, outdoors under actual conditions in real time analysis. There were significant correlations between total coliforms and E. coli removals with abiotic parameters such as pH and dissolved oxygen. From the results, it was observed that in the experiments without shading the removal of total coliforms and E. coli were better. It can be concluded that they were factors acting synergistically for the success of the pathogenic removal of coliforms and this may be the occurrence of endogenous photo-oxidation and oxidative stress in microbial cell leads to DNA damage and cell death due inactivate the metabolic growth of the cells. Further, the final effluent generated by the pond cannot be used for direct reuse, a post-treatment is necessary to fit within the established limits so as to increase the possibilities of its reuse.

Enteric virus removal by municipal wastewater treatment to achieve requirements for potable reuse

Primary and secondary treatment of municipal wastewater contributes to virus removal upstream of advanced purification to produce water for potable reuse. In this study, virus occurrence by cultivable and molecular methods was measured over a 24-month period in raw wastewater influents and secondary effluents from two municipal wastewater treatment plants that together provide the recycled water source for an advanced water purification facility. Using a rank-paired, covariance-based statistical approach, virus log removal values were determined for four wastewater treatment processes that operate in parallel at the two facilities (two activated sludge processes, trickling filter process, and trickling filter/solids contactor process). The trickling filter process exhibited the lowest observed removal of cultivable enteric virus with a median removal of 1.0 log10 (or 90% removal) and a 5th percentile log removal of 0.73 (or 82%), compared to the greatest removal observed for one of the activated sludge processes (median log removal of 2.4 or 99.6% and 5th percentile of 2.1 or 99.2%). Median log removal observed for male-specific (MS) and somatic (SOM) coliphage was 1.8 (98.6% removal) and 0.5 (70%), respectively, for trickling filter and 2.9 (99.9%) and 2.0 (99%) for activated sludge. Thus, coliphage removal was fairly similar to removal observed for cultivable enteric virus. The cultivable enteric virus 5th percentile removal (0.7) from the trickling filter treatment process was proposed to the state regulator for credit towards state requirements for virus removal related to groundwater augmentation with purified recycled water. Receiving pathogen removal credits for secondary wastewater treatment would allow for an improved margin (safety factor) of credits beyond the minimum required; and in this case may also increase the number of viable future groundwater recharge sites closer to drinking water production wells by reducing the underground travel time otherwise required to obtain sufficient credits.

Effect of Hydraulic Loading Rate on Treatment Performance of a Pilot Wetland Roof Treating Greywater from a Household

To solve the upcoming environmental problems, sponge city concepts as well as new technologies are being developed these days. One of the future challenges is to reduce drinking water demand by using decentralized water recycling systems. This study aimed to investigate the performance of a specially designed pilot wetland roof (PWR) treating domestic greywater (GW) at ground level under outdoor conditions and to evaluate the effects of different hydraulic loading rates (HLRs) for a period of two years. The results showed highly efficient removal of typical greywater pollutants from the system, e.g., five-day biochemical oxygen demand (BOD5) > 96%, chemical oxygen demand (COD) > 93%, total suspended solids (TSS) >94%, anionic surfactants (AS) > 94%, ammonium-nitrogen (NH4-N) > 84%, total nitrogen (TN) > 71%, total phosphorous (TP) > 87%, and E. coli (1.86 ± 1.54 log-removal). The mean concentrations of the targeted parameters at the outflow were in compliance with the requirements for discharge to the environment and met reclaimed water quality standards for agricultural irrigation, except for E. coli. Statistically significant (p < 0.05) results of pollutant mass removal rate across different HLRs indicated the potential effect of HLR on treatment performance, and HLR in a range of 67–80 L m–2 d–1 contributed to a higher removal efficiency without compromising the limit values. A comparatively low HLR of 45 L m–2 d–1 should be applicable if pathogen removal is the most important requirement. Plant species showed good plant vitality and adapted well to the water storage mat. The higher the mean ambient air temperature, the greater runoff reduction (>50%) was observed due to high evapotranspiration. The results showed the system is a promising green technology for GW recycling and can be scaled up for application to urban buildings.

Enhancing thermophilic anaerobic digestion of municipal sludge: An investigation

Thermophilic anaerobic digestion (TAD), although less explored as opposed to mesophilic AD is a viable strategy to reduce the volume of municipal sludge and generate renewable energy in the form of biogas simultaneously. In this study, biochemical methane potential was tested to compare three different pretreatments i.e., ultrasonication, biochar (black spruce wood and bark, California almond hull), enzyme (cocktail of endoglucanase, β-glucosidase, xylanase) for their ability to enhance TAD of municipal sludge. In addition to conventional parameters such as chemical oxygen demand (COD), volatile solids (VS), and biogas, the respiratory value and the pathogen removal were also evaluated. Ultrasonication for 20 min was found to be the best pretreatment in terms of higher COD removal, biogas generation and VS reduction. This is possible due to the increase in soluble fraction of organic matter after ultrasonication which facilitated effective hydrolysis and reduction in start-up time. However, pathogen removal was mostly facilitated by AD and the contribution of pretreatment was minimal.

Biomimetic strategy for fabrication of bifunctional graphene oxide-biomaterial aerogel as highly porous antifouling material for oil/water separation

Fabrication of Janus type asymmetric wettable aerogel with high mechanical strength and antifouling property remains a great challenge for effective oil/water separation. Herein, inspired by the lotus leaf structure, we reported eco-benign fabrication of stearic acid coated biomaterial functionalized porous network structure of graphene oxide (GCCS) nanobioaerogel with Janus wettability (water contact angle: 129.4 ± 10.1° at top side and 40.35 ± 2.4° at bottom side), excellent modulus of elasticity (4.74 kPa), and antibiofouling properties. FTIR results revealed that the covalent, electrostatic, hydrophobic, and π-π interactions of graphene oxide (GO) and biomaterials provided high mechanical strength to the GCCS nanobioaerogel. The bifunctional GCCS nanobioaerogel with 50% hydrophobic coating exhibited excellent water floating and anti-overturning behaviour under high waves. Moreover, this asymmetric aerogel simultaneously removed oil through top side and water soluble dyes through bottom of the aerogel at the oil/water interface. The bifunctional GCCS nanobioaerogel exhibited high oil removal capacity and removed 227.53 ± 9.35 g/g of oil due to high surface area and porous structure. At the same time dye adsorption capacity of the GCCS nanobioaerogel was calculated as 204.17 ± 7.49 mg/g at optimum pH = 4.0, 60 °C in both single and multi-component system. In addition, the nanobioaerogel exhibited excellent bactericidal activity (99.999%) along with antibiofouling property and effectively disinfect the bacteria contaminated water. Moreover, the dyes and oils were easily eluted from GCCS nanobioaerogel and recycled multiple times. Thus, this manuscript highlights the potential use of renewable natural biomaterial to fabricate biomimetic porous aerogel material with asymmetric wettability, high mechanical strength and antifouling properties for efficient removal of oil, dyes and microbial pathogens.

Nanostructured copper-organic frameworks for the generation of sulphate radicals: application in wastewater disinfection.

In recent years, the presence of pathogens in the environment has become an issue of widespread concern in society. Thus, new research lines have been developed regarding the removal of pathogens and persistent pollutants in water. In this research, the efficacy of nanostructure copper-organic framework, HKUST-1, has been evaluated for its ability to eliminate Escherichia coli and generate sulphate radicals as catalyst for the treatment of effluents with a high microbiological load via peroxymonosulphate (PMS) activation. The disinfection process has been optimized, achieving complete elimination of Escherichia coli growth after 30 min of testing using a concentration of 60.5 mg/L HKUST-1 and 0.1 mM of PMS. To overcome the operational limitations of this system and facilitate its handling and reutilization in a flow disinfection process, HKUST-1 has been efficiently encapsulated on polyacrylonitrile as a novel development that could be scaled up to achieve continuous treatment.

Visible light responsive AgBiS2 nanomaterials for photocatalytic applications in removal of antimicrobial compounds and bacterial pathogens: Possible electrochemical pathways

Potential synthesis of ternary chalcogenide nanocomposite to showcase a practical electronic pathway to improve photocatalytic efficiency was carried out. In the present study, AgBiS2 nanorod-shaped with remarkably visible-light absorption was prepared using solvothermal techniques. This material was employed in photocatalytic degradation of amoxicillin (AMX) under visible light irradiation. The results indicated more than 90% degradation of AMX under 60 min having a corresponding bandgap of ∼2.19 eV. In the verge of understanding the photogenerated separation of electron-hole pair, VB and CB potentials were calculated to be 2.06 eV and − 0.76 eV, proposing a possible pathway for the degradation study. The photogenerated intermediates were identified using LC-MS analysis and the mineralization was followed using TOC analysis. A scavenging experiment showed a potential reactive oxygen species involved in the oxidation of organics that proved effective in three consecutive trials.In addition, antibacterial and antibiofilm activity showcased fair efficiency of the material, especially the presence of Ag+ in AgBiS2 improves antimicrobial activity. In case of antibiofim activity, 4 × 107 CFU/mL were seen to be most effective for the biomass formation of the biofilms.

Variation of the feeding/resting period in modified vertical treatment wetlands (depth, zeolite as medium) employed for treating rural domestic wastewater in tourist areas.

This work aimed to evaluate the performance of modified vertical flow treatment wetlands (VF-TWs) in terms of depth and medium to assess the effect of the feeding/resting periods and footprint (FP). The modifications were proposed for treating domestic wastewater in rural areas with flow variations such as tourist sites. The experimental setup included six laboratory-scale VF-TWs: (a) normal (VF-N), bed depth 1.0 m, filled with sand and (b) modified (VF-M), bed depth 0.5 m, filled with sand (upper) and zeolite (bottom, saturated). The operation was divided into three phases (3 months each), varying the feeding/resting period and FP: phase I, 5 d/10 d, 2.6 m2/person-equivalent (PE); phase II, 3.5 d/3.5 d, 1.7 m2/PE; and phase III, only feeding no resting, 0.85 m2/PE. Influent and effluent grab samples were taken every 2 weeks. The results showed effective removal (above 60%) of total solids, organic matter, and pathogens for both VF-N and VF-M. Regarding nutrients, VF-M showed a phosphate removal below 60%, but no consistent removal (15-60%) of total nitrogen. Thus, the results suggest that proposed modifications can be an option to be established in tourist sites, but further work should be conducted to improve and optimize total nitrogen removal.

Removal of Pathogenic Bacteria in a Horizontally Fed Subsurface Constructed Wetland Hybrid System

The management of effluents and their treatment is a fundamental issue in water management, the removal of different types of contaminants is another relevant issue for public health and the environment. Bacteria are one of the main types of contaminants in untreated water discharged to receiving bodies. The objective of this research was to evaluate the removal efficiency of pathogenic bacteria in a horizontal feeding subsurface artificial wetland that treats wastewater originated from the Boca de Río Technological Institute, Veracruz, Mexico. A hybrid system composed of seven cells with three types of substrates and ornamental type vegetation was designed; the indicators evaluated were the concentration of total and fecal coliforms and the efficiency of bacterial removal in the stages of the system. The artificial wetland system demonstrated a significant reduction (p < 0.05) between the different cells of the system. The values of pathogenic bacteria removal obtained in the wetland were higher than 99% in the cells of the system and times. In conclusion, it was identified that the interaction of the components of this system and its operation under the climatic seasons of the site influenced the removal efficiency of pathogenic bacteria, allowing optimal removal efficiency.