Development of microbial fuel cell integrated constructed wetland (CMFC) for removal of paracetamol and diclofenac in hospital wastewater

Potentialities of manganese ore and iron-carbon particles for pharmaceuticals and personal care products removal in electroactive constructed wetland

This study explores the use of manganese ore, iron-carbon particles (Fe-C), and gravel as anode fillers in electroactive constructed wetlands (ECWs) to treat wastewater containing pharmaceuticals and personal care products (PPCPs) including ciprofloxacin (CIP), ofloxacin (OFL), and naproxen (NPX), while also assessing bioelectricity production. Although the presence of PPCPs reduced pollutant removal and electricity generation, ECWs outperformed conventional CWs. Specifically, Fe-C ECWs (FC-ECWs) achieved high COD and NPX removal efficiencies of 90.15 % and 62.25 %, respectively, along with the highest power density of 13.25 mW/m2. In contrast, manganese ore ECWs (Mn-ECWs) were more effective at removing NH4+-N, CIP, and OFL, with removal efficiencies of 42.08 %, 67.12 %, and 61.60 %, respectively. Notably, ECWs also facilitated the accumulation of qnrS resistance genes. FC-ECWs promoted both qnrS and intI gene expression, while Mn-ECWs inhibited the spread of antibiotic resistance genes (ARGs). Microbial analysis revealed that Firmicutes in Fe-C correlated with increased bioelectricity production. Additionally, genera like Enterobacter and Proteiniclasticum might act as ARG hosts. These findings highlight the innovation of using different anode fillers to optimize both pollutant removal and bioelectricity generation in ECWs, while also addressing the critical issue of ARG proliferation in wastewater treatment systems.

Magnetic Composite Carbon from Microcrystalline Cellulose to Tackle Paracetamol Contamination: Kinetics, Mass Transfer, Equilibrium, and Thermodynamic Studies

This study reported a one-spot preparation of magnetic composite carbon (MCC@Fe) from microcrystalline cellulose (MC). The pure cellulose was impregnated in iron (III) chloride solution and carbonized at 650 °C. The MCC@Fe composite adsorbent underwent various characterization techniques. XRD identified nanostructured Fe3O4 particles with an average crystallite size of 34.3 nm embedded in the core subunits of the material. FESEM images indicated a rough and irregular surface, with some cavities along its surface, incorporating Fe3O4 nanoparticles, while EDS analysis confirmed the presence of elements like Fe, C, and O. Notably, combining thermal and chemical treatments produces a composite with more pores and a high specific surface area (500.0 m2 g-1) compared to MC (1.5 m2/g). VSM analysis confirmed the magnetic properties (0.76 emu/g), while the Hydrophobic Index (HI) showed that MCC@Fe was hydrophobic (HI 1.395). The adsorption studies consisted of kinetic, mass transfer, equilibrium, and thermodynamics studies. Kinetic study of the adsorption of paracetamol on MCC@Fe composite proved to be rapid, and the time necessary for covering 95% of the surface (t0.95) was lower than 27 min following the fractal-like pseudo-first-order model (FPFO). Liu's isotherm proved to be the most appropriate for understanding the adsorption equilibrium. Remarkably, the maximum sorption capacity (Qmax) of paracetamol was 34.78 mg g-1 at 45 °C. The ΔH° value (+27.00 kJ/mol) and the negative ΔG° values were consistent with the physisorption mechanism and favorable process. Furthermore, the mass transfer mechanism showed that the transfer is governed by the intraparticle diffusion model, with surface diffusion being the rate-limiting step when considering the Biot number greater than 100. This research displayed a single-route production of inexpensive magnetic nano adsorbents capable of efficiently eliminating paracetamol from aqueous environments.

Constructed wetland microbial fuel cell as enhancing pollutants treatment technology to produce green energy

The persistent challenge of water pollution, exacerbated by slow progress in ecofriendly technologies and accumulating pollutants, underscores the need for innovative solutions. Constructed Wetland Microbial Fuel Cell (CW-MFC) emerges as an intriguing environmental technology capable of adressing this issue by eliminating contaminants from wastewater while simultaneously producing green energy as an additional bonus. In recent years, CW-MFC technology has gained attention due to its sustainability and promising prospects for a circular waste-free industry. However, due to various technological and biological challenges, it has not yet achieved wide-scale application. This review examines the current state of CW-MFC technology and identifies both biotic and abiotic strategies for optimization through operational and structural improvements affecting biocomponents. Our review highlights several key findings: (1) Plants play an important role in reducing the system's inner resistance through mechanisms such as radial oxygen loss, evapotranspiration, and high photosynthetic flow, which facilitate electroactive bacteria and affect redox potential. (2) Plant characteristics such as root porosity, phloem and aerenchyma development, chlorophyll content, and plant biomass are key indicators of CW-MFC performance and significantly impact both pollutant removal and energy harvesting. (3) We expand the criteria for selecting suitable plants to include mesophytes and C3 pollutant-tolerant species, in addition to traditional aquatic and C4 plants. Additionally, the review presents several technical approaches that enhance CW-MFC efficiency: (1) design optimization, (2) use of novel materials, and (3) application of external electrical fields, aeration, light, and temperature adjustments. CW-MFCs are capable of nearly complete elimination of a wide range of contaminants, including organic matter (84 % ± 10), total nitrogen (80 % ± 7) and phosphorus (79 % ± 18) compounds, metals (86 % ± 10), pharmaceuticals (87 % ± 7), dyes (90 % ± 8), and other complex pollutants, while generating green energy. We hope our findings will be useful in optimizing CW-MFC design and providing insights for researchers aiming to advance the technology and facilitate its future scaling.

Performance and mechanisms of constructed wetland integrated microbial fuel cell for remediation and detoxification of leather tannery wastewater

Several previous studies concerned of microbial fuel cells integrated into constructed wetlands, nevertheless, their application as a convenient treatment for wastewater is still developing. In this experimental investigation, five CW-MFC systems were similarly designed, setup, and operated in a batch mode for two subsequent cycles. Each cycle lasted for 10 days to evaluate the performance of CW-MFC system for the remediation of real leather tannery wastewater (LTW). Four CW-MFCs were planted, each with different type of vegetation including Conocarpus, Arundo donax, Canna lily, and Cyperus papyrus in CW1-MFC, CW2-MFC, CW3-MFC, and CW4-MFC, respectively. The fifth CW5-MFC was maintained unplanted and considered as the control system. The performance of each CW-MFCs systems was evaluated mainly based on the removal of organic content (COD), total dissolved solid (TDS) elimination, and power generation. The results demonstrated that the four types of plants maintained healthy and no sign of wilting was observed during the 20 days of monitoring. For the first cycle of batch operation, maximum removal efficiencies of COD were 99.8%, 99.5%, 99.7%, 99.6% and 99.5% with power outputs of 10,502.8, 10,254.6, 9956.4, 10,029.6, and 9888.0 mW/m3, while, maximum TDS elimination were 46.7%, 39.7%, 60.8%, 55.5%, and 13.8% observed in CW1-MFC, CW2-MFC, CW3-MFC, CW4-MFC, and CW5-MFC, respectively. Very comparable results were observed in the second operation cycle. Results of phototoxicity test indicated that the germination of Hordeum vulgare and Triticum aestivum were 100% watered with treated effluent compared to 90% accomplished with tap water as the control solution for both types of seeds.

A comprehensive review on the treatment of pesticide-contaminated wastewater with special emphasis on organophosphate pesticides using constructed wetlands

Pesticides pose a significant threat to aquatic ecosystems due to their persistent nature and adverse effects on biota. The increased detection of pesticides in various water bodies has prompted research into their toxicological impacts and potential remediation strategies. However, addressing this issue requires the establishment of robust regulatory frameworks to determine safe thresholds for pesticide concentrations in water and the development of effective treatment methods. This assessment underscores the complex ecological risks associated with organophosphate pesticides (OPPs) and emphasizes the urgent need for strategic management and regulatory measures. This study presents a detailed examination of the global prevalence of OPPs and their potential adverse effects on aquatic and human life. A comprehensive risk assessment identifies azinphos-methyl, chlorpyrifos, and profenfos as posing considerable ecological hazard to fathead minnow, daphnia magna, and T. pyriformis. Additionally, this review explores the potential efficacy of constructed wetlands (CWs) as a sustainable approach for mitigating wastewater contamination by diverse pesticide compounds. Furthermore, the review assess the effectiveness of CWs for treating wastewater contaminated with pesticides by critically analyzing the removal mechanism and key factors. The study suggests that the optimal pH range for CWs is 6-8, with higher temperatures promoting microbial breakdown and lower temperatures enhancing pollutant removal through adsorption and sedimentation. The importance of wetland vegetation in promoting sorption, absorption, and degradation processes is emphasized. The study emphasizes the importance of hydraulic retention time (HRT) in designing, operating, and maintaining CWs for pesticide-contaminated water treatment. The removal efficiency of CWs ranges from 38% to 100%, depending on factors like pesticide type, substrate materials, reactor setup, and operating conditions.

Advancement in constructed wetland microbial fuel cell process for wastewater treatment and electricity generation: a review

The constructed wetland coupled with a microbial fuel cell (CW-MFC) is a wastewater treatment process that combines contaminant removal with electricity production, making it an environmentally friendly option. This hybrid system primarily relies on anaerobic bioprocesses for wastewater treatment, although other processes such as aerobic bioprocesses, plant uptake, and chemical oxidation also contribute to the removal of organic matter and nutrients. CW-MFCs have been successfully used to treat various types of wastewater, including urban, pharmaceutical, paper and pulp industry, metal-contaminated, and swine wastewater. In CW-MFC, macrophytes such as rice plants, Spartina angalica, Canna indica, and Phragmites australis are used. The treatment process can achieve a chemical oxygen demand removal rate of between 80 and 100%. Initially, research focused on enhancing power generation from CW-MFC, but recent studies have shifted towards resource recovery from wastewater. This review paper provides an overview of the development of constructed wetland microbial fuel cell technology, from its early stages to its current applications. The paper also highlights research gaps and potential directions for future research.

Combination of advanced biological systems and photocatalysis for the treatment of real hospital wastewater spiked with carbamazepine: A pilot-scale study

Over the past few decades, the increase in dependency on healthcare facilities has led to the generation of large quantities of hospital wastewater (HWW) rich in chemical oxygen demand (COD), total suspended solids (TSS), ammonia, recalcitrant pharmaceutically active compounds (PhACs), and other disease-causing microorganisms. Conventional treatment methods often cannot effectively remove the PhACs present in wastewater. Hence, hybrid processes comprising of biological treatment and advanced oxidation processes have been used recently to treat complex wastewater. The current study explores the performance of pilot-scale treatment of real HWW (3000 L/d) spiked with carbamazepine (CBZ) using combinations of moving and stationary bed bio-reactor-sedimentation tank (MBSST), aerated horizontal flow constructed wetland (AHFCW), and photocatalysis. The combination of MBSST and AHFCW could remove 85% COD, 93% TSS, 99% ammonia, and 30% CBZ. However, when the effluent of the AHFCW was subjected to photocatalysis, an enhanced CBZ removal of around 85% was observed. Furthermore, the intermediate products (IPs) formed after the photocatalysis was also less toxic than the IPs formed during the biological processes. The results of this study indicated that the developed pilot-scale treatment unit supplemented with photocatalysis could be used effectively to treat HWW.

The influence of various chemical oxygen demands on microbial fuel cells performance using leachate as a substrate

Microbial fuel cells (MFCs), hailed as a promising technology, hold the potential to combat various wastewater pollutants while simultaneously converting their chemical energy into electricity through biocatalysts. This study explores the applicability of a dual compartment MFC (DC-MFC) under varying conditions, targeting the removal of chemical oxygen demand (COD) from landfill leachate and electricity generation. In this setup, anaerobic sludge from a wastewater treatment plant serves as the inoculum in the anode compartment of the MFC, with a Nafion117 membrane acting as the separator between MFC units. The cathode compartments are filled with distilled water and continually aerated for 24 h to enhance air supply. The study assesses the MFC's performance across different COD concentrations, focusing on COD removal, power generation, and Coulombic efficiency. The findings reveal that COD removal efficiency is notably enhanced at higher concentrations of organic matter. Specifically, at a COD concentration of 3325.0 mg L-1, the MFC exhibited the highest COD removal efficiency (89%) and maximum power density (339.41 mWm-2), accompanied by a Coulombic efficiency of 25.5%. However, as the initial substrate concentration increased to 3825 mg L-1, the efficiency decreased to 72%, with a Coulombic efficiency of 13.56% and a power density of 262.34 mWm-2. Optical density levels increased due to bacterial growth at ambient temperature and neutral pH, reflecting the dynamic microbial response within the system.

Enhanced degradation of ibuprofen in an integrated constructed wetland-microbial fuel cell: treatment efficiency, electrochemical characterization, and microbial community dynamics

Over the past few decades, there has been a growing concern regarding the fate and transport of pharmaceuticals, particularly antibiotics, as emerging contaminants in the environment. It has been proposed that the presence of antibiotics at concentrations typically found in wastewater can impact the dynamics of bacterial populations and facilitate the spread of antibiotic resistance. The efficiency of currently-used wastewater treatment technologies in eliminating pharmaceuticals is often insufficient, resulting in the release of low concentrations of these compounds into the environment. In this study, we addressed these challenges by evaluating how different influent ibuprofen (IBU) concentrations influenced the efficiency of a laboratory-scale, integrated constructed wetland-microbial fuel cell (CW-MFC) system seeded with Eichhornia crassipes, in terms of organic matter removal, electricity generation, and change of bacterial community structure compared to unplanted, sediment MFC (S-MFC) and abiotic S-MFC (AS-MFC). We observed that the addition of IBU (5 mg L-1) resulted in a notable decrease in chemical oxygen demand (COD) and electricity generation, suggesting that high influent IBU concentrations caused partial inhibition for the electroactive microbial community due to its complexity and aromaticity. However, CW-MFC could recover from IBU inhibition after an acclimation period compared to unplanted S-MFC, even though the influent IBU level was increased up to 20 mg L-1, suggesting that plants in CW-MFCs have a beneficial role in relieving the inhibition of anode respiration due to the presence of high levels of IBU; thus, promoting the metabolic activity of the electroactive microbial community. Similarly, IBU removal efficiency for CW-MFC (i.e., 49-62%) was much higher compared to SMFC (i.e., 29-42%), and AS-MFC (i.e., 20-22%) during all experimental phases. In addition, our high throughput sequencing revealed that the high performance of CW-MFCs compared to S-MFC was associated with increasing the relative abundances of several microbial groups that are closely affiliated with anode respiration and organic matter fermentation. In summary, our results show that the CW-MFC system demonstrates suitability for high removal efficiency of IBU and effective electricity generation.