Chemical Oxygen Demand Of Wastewater Research Articles

Iron Recycle-Driven Organic Capture and Sidestream Anaerobic Membrane Bioreactor for Revolutionizing Bioenergy Generation in Municipal Wastewater Treatment.

The practicality of intensifying organic matter capture for bioenergy recovery to achieve energy-neutral municipal wastewater treatment is hindered by the lack of sustainable methods. This study developed innovative processes integrating iron recycle-driven organic capture with a sidestream anaerobic membrane bioreactor (AnMBR). Iron-assisted chemically enhanced primary treatment achieved elemental redirection with 75.2% of chemical oxygen demand (COD), 20.2% of nitrogen, and 97.4% of phosphorus captured into the sidestream process as iron-enhanced primary sludge (Fe-PS). A stable and efficient biomethanation of Fe-PS was obtained in AnMBR with a high methane yield of 224 mL/g COD. Consequently, 64.1% of the COD in Fe-PS and 48.2% of the COD in municipal wastewater were converted into bioenergy. The acidification of anaerobically digested sludge at pH = 2 achieved a high iron release efficiency of 96.1% and a sludge reduction of 29.3% in total suspended solids. Ultimately, 87.4% of iron was recycled for coagulant reuse, resulting in a theoretical 70% reduction in chemical costs. The novel system evaluation exhibited a 75.2% improvement in bioenergy recovery and an 83.3% enhancement in net energy compared to the conventional system (primary sedimentation and anaerobic digestion). This self-reliant and novel process can be applied in municipal wastewater treatment to advance energy neutrality at a lower cost.

Performance evaluation of a microbial fuel cell for resource recovery as struvite and bioelectricity generation from slaughterhouse wastewater

AbstractBACKGROUNDThe microbial fuel cell (MFC) is a potential cost‐effective technology for the energy‐neutral treatment of wastewater. However, the successful implementation of this technology in resource recovery is still limited. In this study, a microbial electrochemical cell was designed and operated for 30 days. Critical factors for removal and recovery of nitrogen and phosphorus as struvite from wastewater were assessed.RESULTSOptimization studies on critical factors such as the chemical oxygen demand (COD) of wastewater (500–2000 mg L−1) and cathode aeration rate (45–135 mL min−1) were conducted using a pure culture of Escherichia coli. The system yielded an average power density of 465 mW m−2, average current density of 915 mA m−2 and phosphorus recovery at an extent of 40% as struvite. Additionally, a maximum reduction in the COD of 90% with an average coulombic efficiency of about 82% was obtained at a short interval of 30 days. Solubility studies of the recovered struvite for 12 h at different pH values from 4.5 to 9 showed a maximum solubility of 80% at pH 4.5 and a minimum of 3.5% at pH 9.CONCLUSIONThis study moves one step closer to applying MFC technology for nitrogen‐ and phosphorus‐rich wastewater treatment with concurrent struvite precipitation and electricity production. In this way, Sustainable Development Goals 2, 6 and 7 can be achieved through resource recovery, clean water and bioenergy. © 2024 Society of Chemical Industry (SCI).

Pipeline Terracotta Microbial Fuel Cell: Organic Content Biosensor and Energy Harvesting Device Integrated in Wastewater Pipeline.

Wastewater pipelines are present everywhere in urban areas. Wastewater is a preferable fuel for renewable electricity generation from microbial fuel cells. Here, we created an integrated microbial fuel cell pipeline (MFCP) that could be connected to wastewater pipelines and work as an organic content biosensor and energy harvesting device at domestic waste-treatment plants. The MFCP used a pipeline-like terracotta-based membrane, which provided structural support for the MFCP. In addition, the anode and cathode were attached to the inside and outside of the terracotta membrane, respectively. Co-MnO2 was used as a catalyst to improve the performance of the MFCP cathode. The experimental data showed a good linear relationship between wastewater chemical oxygen demand (COD) concentration and the MFCP output voltage in a COD range of 200-1900 mg/L. This result implies the potential of using the MFCP as a sensor to detect the organic content of the wastewater inside the wastewater pipeline. Furthermore, the MFCP can be used as a long-lasting sustainable energy harvester with a maximum power density of 400 mW/m2 harvested from 1900 mg/L COD wastewater at 25 °C.

Effect of Aeration Rate on Specific Oxygen Uptake Rate (SOUR) in Treating Chemical Oxygen Demand (COD) in Domestic Wastewater

Specific oxygen uptake rate (SOUR) is significant parameter to determine the microbial activity and examined the effluent quality in biological wastewater treatment. Chemical oxygen demand (COD) is the major indicator in monitoring the effluent quality in relation on its removal mainly depends on the microbial activity in the activated sludge. So, this research is conducted to study the effect of aeration rate on SOUR and determined the best oxygen requirement in removing COD in domestic wastewater. The procedure was carried out by using domestic wastewater as the seed sludge in sequencing batch reactor. The reactor with working volume of 2L was operating 6 cycles in 24 hours with five phases (feeding, aeration, settle, draw and idle). The aeration time is fixed to 2.5 hours. The dissolved oxygen and COD readings were recorded with four types of aeration rate adjusted at 1L, 2L, 3L and 4L / min daily for 7 days. The result indicates that, 3L/min gives the highest SOUR which reflects that the high activity of microbial in this condition. Besides, the effluent also shows the highest COD removal efficiency on 3L/min of aeration rate. So, as a conclusion the best oxygen requirement for the microbial to carry out their activities on aeration rate of 3L/min.

Effect and mechanism of iron-carbon micro-electrolysis pretreatment of organic peroxide production wastewater.

The wastewater from organic peroxide production has high chemical oxygen demand (COD) concentration and poor biodegradability, so it is necessary to find a cost-effective treatment method. The iron-carbon microelectrolysis (IC-ME) technology was used to pretreat the organic peroxide production wastewater, and the influence of reaction conditions on the removal effect of pollutants and the degradation mechanism were studied. The effects of initial pH, iron filings, iron-carbon ratio, and reaction time on the wastewater treatment were investigated by single-factor and response surface optimization experiments, and the degradation mechanism was analyzed by three-dimensional fluorescence spectroscopy, UV-Vis, and gas chromatography mass spectrometry (GC-MS). The experimental results showed that the COD removal efficiency was 35.67% and the biodegradability of wastewater was increased from 0.113 to 0.173 under the conditions of initial pH of 3.1, the dosage of iron filings of 30.5g/L, the ratio of iron-carbon of 1.01, and the reaction time of 122.8min, and the process of IC-ME for degrading COD of wastewater from the production of organic peroxide was consistent with the secondary reaction. The IC-ME process could decompose macromolecular organic compounds such as tyrosine proteins and aromatic proteins, and improve the biodegradability of wastewater. It provides a theoretical reference for the practical application of IC-ME to treat this type of wastewater.

Synergistic removal of organics from semi-coke wastewater by persulfate and cyanide tailings

In this study, the persulfate and cyanide tailings (PS-CTs) were used for the synergistic treatment of semi-coke wastewater to achieve advanced oxidation and in-situ coagulation removal of organics in semi-coke wastewater. The effects of persulfate concentration, reaction temperature, cyanide tailing concentration and initial pH on chemical oxygen demand (COD) removal efficiency were investigated, and the synergistic mechanism in the treatment process was further explored. The results showed that the removal efficiency of COD in semi-coke wastewater was 94.49 % under the conditions of persulfate concentration 0.025 mol/L, reaction temperature 60 °C, cyanide tailings concentration 5 g/L, the initial pH value of 3. The results of the mechanistic analysis showed that in PS-CTs system, pyrite was oxidized by persulfate. The dissolved Fe2+ activated the persulfate to produce SO4− and OH and generated Fe3+ in situ. The hydrolysis of Fe3+ produced a series of complex ions and amorphous iron hydroxides, which could remove some organics by adsorption and sweeping netting. The organics in semi-coke wastewater were effectively removed by the combined effect of oxidation and coagulation. In addition, the PS-CTs system also achieved the oxidative de-cyanidation of cyanide tailings simultaneously, and the total cyanide concentration of treated cyanide tailings was 8.21 mg/kg, and the leaching cyanide concentration was 0.12 mg/L, which was in line with the emission standards. This process implemented the concept of “treating waste with waste”, and provided theoretical support for the treatment of semi-coke wastewater and other organic wastewater.

The effectiveness of using coconut husk powder as an adsorbent to enhance the wastewater quality of the cepuk textile industry in Nusa Penida, Bali, Indonesia

Introduction: Tenun Cepuk (traditional woven) from Nusa Penida holds great potential as a traditional textile art form, cherished for its intricate patterns and cultural significance. However, the textile industry's wastewater, with its dye-related pollution, presents a significant environmental challenge that needs sustainable solutions. Coconut husk powder exhibits promising potential as an adsorbent for treating dye wastewater from the textile industry. Investigating the interplay between varying thicknesses and contact durations is crucial to maximizing coconut husk powder's adsorption capacity and efficiency for dye wastewater treatment. Method: This study, following an Experimental research design with a Posttest Only Control Group Design, aims to assess the impact of an intervention on the experimental group compared to the control group. Coconut fibers, sourced from Nusa Penida agriculture, serve as the adsorbent. Coconut powder is added to these tanks at thicknesses of 5 cm, 10 cm, and 15 cm. Subsequently, wastewater samples from the Cepuk weaving process are introduced into each experimental tank, along with a control group. The process is left for 24 and 72 hours as varying contact times. The adsorption results are subjected to analysis for parameters, including total suspended solids (TSS), total dissolved solids (TDS), five-day biochemical oxygen demand (BOD5), and chemical oxygen demand (COD) at the Panureksa Denpasar Laboratory. Results: The use of coconut husk powder as an adsorbent effectively lowers TDS, TSS, BOD5, and COD in Cepuk textile dye wastewater. The reduction depends on adsorbent thickness and contact time. Thicker adsorbents notably reduce TDS, TSS, BOD5, and COD, enhancing wastewater quality and environmental safety. A 15 cm-thick adsorbent effectively reduces TDS to permissible levels. Prolonged contact times also significantly lower levels. Conclusion: Coconut husk powder can be utilized to decrease TDS, TSS, BOD5, and COD levels in textile dye wastewater. Thickness and contact time significantly impact the enhancement of wastewater quality.

Catalytic valorization of Kraft lignin into feedstock chemicals with methyltrioxorhenium (MTO) catalyst in microbial electrochemical cell

In this study, the authors investigate a novel approach to valorize Kraft lignin using the catalyst Methyltrioxorhenium (MTO) in tandem with in-situ produced H2O2 in a Microbial Electrochemical Cell (MEC). This study demonstrates the in-situ oxidation of Kraft lignin using different concentrations of MTO catalyst (2 mM to 8 mM) and H2O2 (5.24 ± 0.40 mM to 8.91 ± 0.70 mM) in three MECs. The depolymerized Kraft lignin samples were characterized using FTIR, CHNS/O, and 1H NMR analysis. The MTO/H2O2 combination showed high selectivity towards the oxidation of Kraft lignin, resulting in both aromatic ring and side chain cleavage reactions and the production of valuable feedstock chemicals. The oxidation also led to a reduction of 68.42 % to 78.18 % in Chemical Oxygen Demand (COD) of lignin. The selective oxidation favored the recovery of Guaiacyl (G) unit-derived feedstock chemicals, with Guaiacol being the most abundant compound (45.04 mg/mL) among the quantified products by HPLC. Additionally, the system demonstrated high efficiency in anodic wastewater treatment, achieving BOD and COD removal rates ranging from 67.68 % to 72.55 %. This method showcases the use of a sustainable system in combination with a selective catalyst to produce valuable products from usually discarded Kraft lignin while simultaneously treating wastewater.

Performance of trembesi seed (Samanea saman) on tempeh wastewater treatment (a case study in Semanan Tempeh Industry), West Jakarta

Tempeh wastewater contains organic matter, TSS, and high turbidity, which negatively impact if discharged directly into water bodies. The use of biocoagulant from trembesi seeds to treat wastewater is considered more environmentally friendly, easy to find, and affordable. The purpose of this research is to determine how effective trembesi seeds are as a coagulant in removing turbidity, Total Suspended Solid (TSS), Biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD) from tempeh wastewater in a batch-stirred reactor. Jar test with dose variations of 10-700 mg/L, finding the optimum stirring duration for coagulation at 200 rpm with time intervals of 1-3 minutes and for flocculation at 80 rpm with time intervals of 15, 30, and 45 minutes. The findings show that using a coagulant concentration of 500 mg/L resulted in a 63% reduction in turbidity. The optimum coagulation duration is 2 minutes and flocculation is 30 minutes. BOD initially at 1,245 mg/L decreased by 78% to 273 mg/L. COD initially at 6,400 mg/L decreased by 40% to 3,840 mg/L. TSS initially at 609 mg/L decreased by 66% to 205 mg/L. The percentage of allowance for BOD, COD, TSS, and turbidity using a reactor is 68%, 35%, 58%, and 70%. From these results it can be said that trembesi seed coagulant is effective in removing BOD, COD, TSS, and turbidity in tempeh wastewater.

Kinetic modelling for COD and nitrate-N removal from hatchery wastewater through biological approach

This study was conducted to determine the nutrient removal efficiency via the application of mixed cultures from the synthetic hatchery wastewater based on the first-order, second-order and Stover Kincannon models. The synthetic wastewater was prepared according to the characterization of the collected hatchery wastewater sample, and the collected mixed cultures from the pond sediment were acclimatized accordingly. The samples were tested for chemical oxygen demand (COD) and nitrate-N concentration using a Hach spectrophotometer to determine the removal value of the nutrients. The findings show that the highest removal percentage for COD was up to 31.35% on day 3. Meanwhile, the highest removal percentage for nitrate-N was obtained on day 4 at 43.48%. The obtained correlation coefficient, for COD through first-order, second-order, and Stover Kincannon models is 1, 0.6774, and 0.965, respectively, suggesting that the kinetics of COD removal can be described most properly by the first-order model. A similar model was also reported for nitrate-N with value of 1, 0.7563, and 0.8693 for the first-order, second-order, and Stover Kincannon models, respectively. Based on the findings, the acclimatized mixed culture used in this study could be a potent natural COD and nitrate-N removal in the hatchery wastewater.

Impact of Natural Microorganisms on the Removal of COD and the Cells Activity of the Chlorella sp. in Wastewater

In the treatment of wastewater containing only chemical oxygen demand (COD) by Chlorella sp., the cell activity and proliferation ability of Chlorella sp. decreased with the culture time, which affected the removal of COD in wastewater. To solve these problems, the Chlorella sp.–natural microorganism symbiosis system was prepared. The system was used to explore how natural microorganisms affect the cell activity and the proliferation ability of Chlorella sp. in wastewater. In the treatment of COD by Chlorella sp., the removal rate of COD decreased from 45.47% to 28.88%, with a decrease in the cell activity and proliferation ability of Chlorella sp. In the Chlorella sp.–natural microorganism symbiotic system, the removal rate of COD reached 45.75%. With the introduction of natural microorganisms, the circulation of CO2 and O2 between Chlorella sp. and natural microorganisms promoted photosynthesis and respiration, which enhanced the cell activity of Chlorella sp. Under the condition that the dosage of natural microorganisms was between 1% and 6%, the concentration of Chlorella sp. was close to the logarithmic growth phase, which maintained the proliferation ability of Chlorella sp. At the same time, the natural microorganisms grew and proliferated in wastewater containing only COD through preying on Chlorella sp.

Experimental study of microwave-catalytic oxidative degradation of COD in livestock farming effluent by copper-loaded activated carbon

ABSTRACT The problem of massive discharge of livestock wastewater is becoming more and more severe, causing irreversible damage to the ecological environment, and how to treat livestock wastewater efficiently and rapidly deserves to be studied in depth. In this work, CuO/granular activated carbon (GAC) loaded catalysts were prepared and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption/desorption techniques, and X-ray energy spectroscopy (EDS). The results showed that CuO was successfully attached to the GAC surface with good adsorption performance. The effects of catalyst dosage, H2O2 dosage, initial pH, microwave power and microwave irradiation time in different reaction systems on the degradation efficiency of chemical oxygen demand (COD) in wastewater were investigated, and the orthogonal experiments were used to explore the importance ranking of these factors. The highest degradation rate of COD was found to be enhanced by 12.1% in the reaction system of CuO/GAC, and the initial pH had the greatest effect on the COD removal rate. The combined MW/catalyst/H2O2 method used in this work provided a rapid and effective degradation of COD in wastewater, which can be helpful for reference in other microwave catalytic oxidation studies.

Alkaline Prehydrolysis Prolongs Resin Life and Enhances the Adsorption of Phenolic Compounds

Phenolic compounds in oil wastewater are highly toxic and refractory. Hydrolysis at pH 12 for 12 h makes these compounds more vulnerable to attack and destruction. Under the binding and precipitation of polyaluminum chloride (PAC) at pH 8, the chemical oxygen demand (COD) was significantly reduced by 38%. The simulation found that hydrolysis + flocculation was a complex multistep process. The COD removal rate was mainly controlled by the prehydrolysis process. The metabolic pathway suggested that the m-cresol produced in the factory was oxidized to low water-soluble aldehyde. Alkaline hydrolysis converted the aldehyde into m-toluene-methanol, which was conducive to being captured by the PAC. Fourier transform infrared spectroscopy (FTIR) showed that the alkaline dehydrogenation of two m-methylphenyl carbinols produced a molecule that was removed by the resin. Generally, the particle size of the residue after alkaline hydrolysis was 6.4–8.3 nm, which was included in the pore size range of the resin. Therefore, the resin adsorption capacity for the hydrolyzed substances increased to 47,000 mg L−1, with 93% renewability. In short, hybrid technology reduces the concentration burden of the resin inflow and controls the molecular size of adsorbed substances for repurification. It strengthens the treatment effect of high COD wastewater and provides innovative ideas for extending the service life of resin.

Effect of lignocellulose/montmorillonite immobilized Bacillus sp. on monosodium glutamate wastewater.

A group of Bacillus sp. was extracted from monosodium glutamate wastewater. Lignocellulose/montmorillonite composite was selected as the carrier. Lignocellulose/montmorillonite composite immobilized Bacillus sp./calcium alginate microspheres were prepared by immobilized microorganism techniques. The microspheres were used to treat monosodium glutamate wastewater with significantly reduced ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) concentrations. The optimum preparation conditions of microspheres in the treatment of NH3-N and COD of monosodium glutamate wastewater were studied. The concentration of sodium alginate was 2.0 wt%, lignocellulose/montmorillonite was 0.06 wt%, Bacillus sp. was 1.0 wt%, CaCl2 solution was 2.0 wt%, coagulation time was 12h, and the removal capacities of NH3-N and COD were 44832 and 78345mg/L, respectively. The surface structure, element content, functional group change, and crystal structure of the microspheres were characterized by SEM, EDS, and other methods. The results showed that the -COOH in lignocellulose/montmorillonite and the -OH in the Bacillus sp. form intermolecular hydrogen bonds. The Si-O and Al-O bonds in lignocellulose/montmorillonite reacted with sodium ions in sodium alginate. New crystal structures appear inside the material after crosslinking, and the microspheres was formed. Thus, the study has shown that the microspheres were successfully prepared and contributes to the treatment of NH3-N and COD in monosodium glutamate wastewater. This work can provide an interesting strategy for the removal of COD and NH3-N in industrial wastewater by reasonably combining bio-physicochemical processes.

Fungal Strain as Biological Tool to Remove Genotoxicity Effect of Phenolic Compounds from Olive Mill Wastewater

This study aims to select fungi isolates to reduce olive mill wastewater (OMWW) chemical oxygen demand (COD) and phenolic compounds (PC), as well as their genotoxicity effect. Treatment with mold, isolated by an innovative technique using phenolic compound-selective media, showed a reduction rate of about 4% for COD and 2% for PC during one month of incubation without optimization of the treatment conditions. Whereas this percentage reached 98% and 96% for COD and PC, respectively, after only 12 days of treatment, when the C:N ratio was adjusted to 30 by adding urea as a nitrogen source at 150 rpm agitation speed. Genetic sequence homology of the most efficient mold isolate showed 100% similarity to Penicillium chrysogenum. High-performance liquid chromatography analysis of phenolic extracts of untreated OMWW showed the presence of five compounds—hydroxytyrosol at 1.22 g.L−1, tyrosol at 0.05 g.L−1, caffeic acid at 0.16 g.L−1, p-coumaric acid at 0.05 g.L−1 and oleuropein at 0.04 g.L−1—that were eliminated during the degradation process at 88.82%. Genotoxicity, assessed by the Vicia-faba root cell, showed a significant decrease in micronucleus frequency of about 96% after fungal treatment. These results confirm the positive role of fungal treatment of OMWW to eliminate genotoxicity and their ability to improve the agronomic potential.

Effect of bio-electrochemical systems on the removal of organic and inorganic membrane fouling from anaerobic membrane bioreactors

To alleviate the fouling of membrane bioreactors, a coupling system was constructed in which a conductive membrane served as the anode of a bio-electrochemical system, whereas ordinary carbon felt served as the cathode. The membrane module showed approximately 90 % performance for wastewater chemical oxygen demand removal. As the external resistance increased from 50 to 1500 Ω, the number of operating days increased from 25 to 62. The respective concentrations of polysaccharide and protein on R-1500 membrane surface were 6.81- and 2.05-fold greater than the concentrations on the R-50 membrane, and the concentration of Ca2+ on the surface of the R-50 membrane was 1.48-fold greater than the concentration on the R-1500 membrane. Therefore, inorganic fouling is the main type of membrane fouling in coupled systems with low external resistance. For coupled systems with higher external resistance, severe organic fouling eventually causes membrane blockage. Variance partitioning analysis showed that the micro-electric field contributed to 95.34 % of the effect on the control of membrane fouling, significantly greater than the 67.19 % contributed by the current. Therefore, in the system where organic and inorganic fouling coexists, appropriate enhanced field strength (increase in external resistance) is particularly important for membrane fouling control.

Industrial indigo dyeing wastewater purification: Effective COD removal with peroxi-AC electrocoagulation system

Direct current (DC) electrocoagulation has obvious decolorization effect on indigo dyeing wastewater produced in actual production, while the removal rate of chemical oxygen demand (COD) was less than 40%, accompanied by serious electrode corrosion and high energy consumption. In order to enhance the COD removal rate, reduce the electrode loss and power consumption, a peroxi-alternating current (AC) electrocoagulation (EC) system was constructed. With COD as the main evaluation index, the effects of power type, electrode combination and process parameters on COD removal rate and decolorization rate were focused on and explored, as well as revealing the degradation mechanism of COD. The results showed that AC electrocoagulation enhanced the floc adsorption capacity by improving the floc structure, and the COD removal rate after treatment was 51.19%. The coupled system of peroxi-AC electrocoagulation further removed sulfite and residual dyes in the wastewater, and the COD removal and decolorization rate of the treated wastewater reached 78.09% and 98.47%, respectively. In addition, the specific energy consumption analysis of COD removal showed that the coupled system was far less energetic than the DC electrocoagulation process, with only 30% of its energy consumption. The uniform corrosion of the electrode under the action of AC weakened the passivation, which reduced the electrode loss and power consumption by 22.73% and 43.75%, respectively. Results from the present work indicated that the peroxi-AC EC system could be an effective method for reducing the concentration of COD in indigo dyeing wastewater.

Integrated Photocatalytic Oxidation and Adsorption Approach for the Robust Treatment of Refinery Wastewater Using Hybrid TiO2/AC

This study reports the removal of hydrocarbon (HC) pollutants from petroleum refinery wastewater by integrated photocatalytic oxidation and adsorption using a TiO2/AC hybrid material. The hybrid adsorbent/catalyst was prepared by the impregnation of TiO2 over AC and characterized by FTIR, SEM, EDX, and XRD analyses. Under the optimized reaction conditions of pH 3, 30 °C, and 1000 mg TiO2/AC per 500 mL of sample in 50 min, the integrated photocatalytic oxidation-adsorption achieved a net percentage removal of benzene, toluene, aniline, and naphthalene of 91% from model HC solutions. Under these conditions, for the treatment of real refinery wastewater, TiO2/AC caused a 95% decrease in chemical oxygen demand (COD). The integrated photocatalytic oxidation and adsorption using TiO2/AC showed a clear advantage over the individual adsorption and photocatalytic oxidation using AC and TiO2, whereby about the same level of removal of model HCs and a decrease in the COD of refinery wastewater was attained in 105 min and 90 min, respectively, utilizing larger adsorbent/catalyst dosages. GC-MS analysis revealed that during the integrated process of adsorption-photocatalytic oxidation, all the parent HCs and oxidation byproducts were completely removed from the refinery wastewater. Based on the outstanding performance, cost-effectiveness, and environmental greenness, the newly designed TiO2/AC via the integrated adsorption-photocatalytic oxidation can be counted as an effective alternative route for the large-scale processing of refinery wastewater.

Phytoremediation: A Novel Review on the Efficacy of Aquatic Plants in the Wastewater Treatment

Wastewater causes significant environmental harm. Researchers have created a variety of approaches to address this issue. In this study, phytoremediation technology was used to remove pollutants from wastewater so that it could be used for other purposes. This technology is one of the most promising because it is inexpensive, ecologically benign, and effective at removing pollutants. Using a methodical mapping approach, the aquatic plant is treated for domestic, commercial, and municipal wastewater as part of the phytoremediation process. Additionally, a comparative descriptive approach was used for the studied variables in the exclusions where it has been found that Eichhornia Crassipes is an aquatic weed that detached NO2- and NO3- up to 93% of industrial wastewater, High CNP-content wastewater was treated using canna lilies. The removal of BOD3 (biological oxygen demand) and COD (chemical oxygen demand) ranged from 69.8 to 96.4% and 63.6 to 99.1%, respectively. In 21 days, Azolla filiculoides eliminated from municipal wastewater BOD (63%), PO43 (84%), SO42- (83%), Cl (76%), NO3- (76%), COD (79%), and EC (49%).

Compact fluidic electrochemical sensor platform for on-line monitoring of chemical oxygen demand in urban wastewater

• Carbon-silica (C/SiO 2 ) thin films produced by sol–gel chemistry. • C/SiO 2 electrode fabrication at wafer-scale by photolithography / etching process. • Excellent electrochemical performance shown by the fabricated electrodes. • Electrochemical sensor integrated in a modular fluidic system for in-field use. • Cu NPs-modified C/SiO 2 sensor used for on-line analysis of COD in urban wastewater. The rapid expansion of urban areas has given rise to the generation of large amounts of wastewater that pose a growing pressure on the surrounding ecosystems. Effective water quality surveillance programs demand the implementation of in-field tests to monitor water safe discharge in the environment after being adequately treated. This paper describes the manufacturing and application of a miniaturized electrochemical sensor for measuring dissolved chemical oxygen demand (COD) in surface waters entering and exiting urban wastewater treatment plants (UWWTP). Thin-film carbon electrodes are produced on Si/SiO 2 substrates by a combined sol–gel material synthesis and photolithography/dry etching process at the wafer level and show superior electrochemical performance compared with the glassy carbon standard electrode. Three-electrode electrochemical cells of planar configuration are produced and the COD sensor is manufactured by electrodepositing copper nanoparticles (Cu NPs) on the working electrode under controlled potentiostatic conditions. A simple fluidic electrochemical sensor device is fabricated and allows for the Cu NPs electrodeposition as well as analytical sensor performance in an automatic fashion. A linear range up to 670 mg·L -1 O 2 and a limit of detection of 30 mg·L -1 O 2 are achieved. The ability of this electrochemical sensor approach to monitoring the soluble organic load of urban wastewater in real-time is evaluated by analyzing three samples collected in different locations of an UWWTP. The COD values estimated with the sensor are in excellent agreement with those obtained using the standard dichromate method provided by an accredited laboratory. This analytical platform provides a robust, user-friendly low-maintenance flow sensor approach for deployed analysis of COD that could aid to control the effectiveness of water treatment processes, especially when facing water influents containing organic overloads due to changing weather conditions or any anthropogenic phenomena.