Wastewater Treatment Research Articles

Potential of different biobed–biopurification systems in the treatment of domestic sewage

ABSTRACT Four biobed–biopurification systems (BBPS1, BBPS2, BBPS3, and BBPS4) were constructed for the treatment of wastewater. These biobeds were filled with different materials such as rice husk, soil, vermicompost, gravel, and sand as substrates. A total of 5 L of primary treated effluent was provided to each setup and the effluents were analysed after different retention intervals, i.e., 0, 24, 48, and 72 h for different physio-chemical properties. The findings of the experiment showed that BBPS1, BBPS2, BBPS3, and BBPS4 were highly efficient in removing organic impurities but much less efficient in eliminating physical impurities. Much faster removal of the pollutants was achieved in BBPS1 and BBPS2 in comparison to BBPS3 and BBPS4. Both the BBPS1 and BBPS2 beds created favourable circumstances for organic contaminants to biodegrade as BOD removal efficiency was 55.35 and 56.44% and COD removal efficiency was 85.15 and 70.9%, respectively. Both the setups, i.e., BBPS1 and BBPS 2 are also much more efficient for the removal of biogenic contaminants, i.e., 85.7 and 73.2% for nitrate and 65.12249 and 76.99743% for phosphate, respectively. Overall, the performance of BBPS2 proved to be excellent in comparison to other setups, by calculation of its removal efficiency percent for different parameters.

Balancing Surface Chemistry and Flake Size of MXene-Based Electrodes for Bioelectrochemical Reactors.

MXenes have excellent properties as electrode materials in energy storage devices or fuel cells. In bioelectrochemical systems (for wastewater treatment and energy harvesting), MXenes can have antimicrobial characteristics in some conditions. Here, different intercalation and delamination approaches to obtain Ti3C2Tx MXene flakes with different terminal groups and lateral dimensions are comprehensively investigated. The effect of these properties on the energy harvesting performance from wastewater is then assessed. Regardless of the utilized intercalant molecules, MXene flakes obtained using soft delamination approaches are much larger (up to 10µm) than those obtained using mechanical delamination methods (<1.5nm), with a relatively higher content of ─O/─OH surface terminations. When employed in microbial fuel cells, electrodes made of these large MXene flakes have demonstrated a power density of over 400% higher than smaller MXene flakes, thanks to their lower charge transfer resistance (0.38Ω). These findings highlight the crucial role of selecting appropriate intercalation and delamination methods when synthesizing MXenes for bioelectrochemical applications.

Comparative Analysis of Conventional Treatment and Advanced Oxidation Applied to Effluent from Stabilization Ponds in Terms of Subsequent Reuse of Treated Water

The possibility of reusing the effluent from Cuena’s wastewater treatment plant WWTP is analyzed through the application of two treatments: conventional physical–chemical (coagulation, flocculation, sedimentation and filtration, and disinfection) and advanced oxidation with a combination of hydrogen peroxide/ozone. The results show that neither treatment method independently resolves all the limitations of the effluent for reuse, especially regarding organic matter, nutrients, and turbidity. Therefore, the compatibility of the quality of the treated water quality is evaluated for three potential reuses such as unrestricted urban use, recreational use with primary contact, and agricultural irrigation, referencing EPA and Ecuadorian TULSMA standards. This study highlights the need to establish a legal and regulatory framework for water reuse in Ecuador to enable decision-makers to implement sustainable water reuse practices and manage scarcity effectively.

Construction of Lamellar CoFe-LDHs@MoS2 to Promote Permonosulfate Properties Leading to Effective Photocatalytic Degradation of Norfloxacin

The utilization of the photo catalytic activation of permonosulfate (PMS) for the combined breakdown of pollutants has become a focal point in research. Layered double hydroxides (LDHs) have a unique layered structure which is conducive to the adsorption and diffusion of reactants, and can provide more active sites for photocatalytic reactions. The anions between the layers can be exchanged with a variety of substances so that specific catalytically active species can be introduced as needed. LDHs themselves have certain catalytic activity, which can produce synergistic catalysis between LDHs and the supported photocatalytic active substances, and further improve the degradation effect of antibiotics. In actual wastewater treatment, LDHs as a catalyst carrier have a good application prospect. However, the poor activation effect is attributed to the low separation efficiency of catalyst carriers and insufficient active sites. In this study, a dual active site system consisting of Co and Fe, known as CoFe-LDHs@MoS2, was developed as a catalyst to facilitate the synergistic degradation of norfloxacin (NOF) by PMS under visible light. The findings demonstrate that the material possesses an effective capacity for the synergistic degradation of NOF. A comprehensive investigation was conducted to assess the impact of different catalysts, PMS dosage, degradation systems (Vis, PMS, or Vis PMS), catalyst dosage, NOF concentration, pH, and cycle times on the degradation performance. The active free radicals, degradation pathways, and intermediate toxicity were elucidated through capture experiments, Electron Paramagnetic Resonance Spectrometer (ESR) analysis, a liquid mass spectrometry (LC-MS) toxicity assessment, and theoretical calculations. This research offers a novel approach for designing catalysts with exposed high activity sites for the effective removal of NOF from environmental water.

Occurrence and Removal of Antibiotics in Wastewater Treatment Plants during the COVID-19 Pandemic

Occurrence and Removal of Antibiotics in Wastewater Treatment Plants during the COVID-19 Pandemic

Enhancing Tannic Acid-Arginine Complex Loading in Ultraporous PA6 Nanofibers through NH3 Foaming for Efficient Heavy Metal Removal from Textile Wastewater.

Metal-containing dyes in the textile industry release heavy metal ions into wastewater, posing significant environmental risks and complicating treatment processes. Among various removal methods, chemical adsorption through functional groups that form stable complexes is one of the most effective. Tannic acid (TA), renowned for its strong chelation of metal ions via phenolic hydroxyl groups, faces challenges in operation and recycling in its powdered form. Electrospun polyamide 6 (PA6) nanofiber membranes, characterized by high surface area and structural stability, offer a promising platform. However, achieving an optimal TA loading remains a technical hurdle for industrial applications. To address this, we developed an arginine (l-Arg) bridging strategy to enhance the TA loading on PA6 nanofibers. Additionally, we implemented an NH3 escape foaming technique to increase membrane porosity by 20% and quadruple pore size, enhancing surface roughness and resulting in a 70% increase in TA loading. The optimized adsorbent demonstrated the effective removal of various heavy metal ions, achieving over 95% removal efficiency for five different metals. Even after five adsorption-desorption cycles, the membrane retained over 92% efficiency, translating to a treatment capacity of 12.5 tons of wastewater per kilogram of foaming fiber, underscoring its potential for practical wastewater treatment applications.

Biosorption of petroleum compounds from aqueous solutions using walnut shells

Herein, a walnut shell as a biosorbent was applied to remove petroleum compounds from the water medium. The characterization analyses of the walnut shells showed the macro-mesopore structure of the walnut shells, a specific surface area of 26 m2/g, and the presence of various functional groups (-OH, -COOH, -C = O). The CCD design showed that the walnut shell can remove 84.43% of petroleum compounds at pH = 3 (the optimum pH), adsorbent dosage: 2 g/L, and initial concentration of petroleum compounds: 550 mg/L. The study of kinetics and adsorption equilibrium indicated matching the experimental data with the pseudo-second-order kinetic model and Freundlich equilibrium isotherm, respectively. The maximum adsorption ability of walnut shell was 3038.29 mg/g at 45 °C. The ability to regenerate and reuse the walnut shell was investigated in 6 cycles, and the results showed a 21% decrease in adsorption ability after 6 cycles. The obtained data showed that the walnut shells could be a promising adsorbent with high adsorption ability toward petroleum components. Also, the walnut shell is a regenerable adsorbent, low-cost, and environmentally friendly, and can be effective in successive cycles. Therefore, this biosorbent can have a superb influence on wastewater treatment technology and possible applications at an industrial scale.

Green synthesis of copper oxide and titanium dioxide nanoparticles using Santalum album leaf extract for enhanced wastewater treatment

Green synthesis of copper oxide and titanium dioxide nanoparticles using Santalum album leaf extract for enhanced wastewater treatment

The Role of Innovative Technologies in Reducing the Load on Wastewater Treatment Plants in the Cities of the Republic of Kazakhstan

This article highlights an important aspect of modern management of urban wastewater treatment plants in the cities of the Republic of Kazakhstan, focusing on economic assessment of the effectiveness of integrated use of ecosystem solutions for surface (atmospheric) water collection. The study presents an analysis of the impact of such solutions on reducing the burden on wastewater treatment plants and optimizing operating costs. The authors consider different technologies and methods for surface water harvesting, including the use of green spaces, ecosystem elements, and innovative engineering solutions. The paper emphasizes the importance of considering economic aspects when deciding on the implementation of such ecosystem approaches. It presents examples of countries that have implemented, or are currently implementing integrated surface water management and the methods of ecosystem solutions that have shown the most positive ecological and economic effects after their implementation. In addition, the work considers and calculates the main components and concentrations of pollutants entering water bodies from urban areas. The authors conclude that the integrated use of ecosystem solutions for surface water harvesting is a promising approach that will not only reduce the burden on wastewater treatment plants but also contribute to the creation of more sustainable and cost-effective water management systems in the cities of the Republic of Kazakhstan.

Free-Standing Nanocomposite Au@Graphene Oxide Continuous Flow Synthesis in Water for Degradation of Organic Dyes.

We have developed a rapid and facile method for preparing free-standing nanocomposite of gold nanoparticles with graphene oxide (Au@GO) in water under continuous flow in the absence of harsh reducing agents and any other auxiliary substances, as a method with favourable green chemistry metrics. This uses a vortex fluidic device (VFD) where induced mechanical energy and photo-contact electrification associated with the dynamic thin film in the rapidly rotating tube tilted at 45° while simultaneously UV irradiated (λ=254 nm, 20 W) results in decomposition of water to hydrogen and hydrogen peroxide with growth of the gold nanoparticles on the surface of the GO. We have established that the resulting Au@GO composite sheets rapidly catalyse the degradation of commercial dyes like methyl orange (MO) and methylene blue (MB) using the hydrogen peroxide generated in situ in the VFD. This process relies on active radicals generated through liquid-solid photo-contact electrification of water in the VFD which dramatically minimises the generation of waste in industrial applications, with the reaction having implications for wastewater treatment.

Constructing ZnO/NiO Nanocomposites as a Photocatalyst and Investigating Photocatalytic Effectiveness for Wastewater Treatment.

The goal of the present work is to create ZnO/NiO nanocomposites (NCs) for the photocatalytic destruction of organic contaminants using the co-precipitation technique. To investigate physiochemical characteristics, FT-IR, UV visible spectroscopy, SEM, and XRD were used. The ZnO hexagonal phase and the NiO cubic phase in the ZnO/NiO NCs were verified by the diffraction pattern. NCs were discovered to have larger average crystallite sizes. The bandgap energy calculated from the Tauc plot for the ZnO is 3.02 and 2.74 eV for the ZnO/NiO NC's. SEM analysis revealed the morphological study and particle size was calculated using the histogram technique and found to be 124.5 nm for the ZnO and 49.2 nm for the ZnO/NiO NCs. Photocatalytic degradation in the presence of sunlight showed 72.8% degradation of Methylene blue (MB) for the ZnO and 79.2% for the ZnO/NiO NCs. The increase in the photocatalytic capablity for the NCs is attributed to the synergistic effect between ZnO and NiO which effectively separated charge carriers preventing greater recombination rate. The robustness of ZnO/NiO NCs as a catalyst option was shown by their exceptional performance.

Combined Effects of Treatment and Sewer Connections to Reduce Future Microplastic Emissions in Rivers.

Global mitigation strategies are needed to reduce the amount of microplastics reaching our oceans via rivers. However, what strategies will be most effective, and when and where to implement these strategies is unclear. We applied the global water quality model MARINA-Plastics, covering 10,226 sub-basins worldwide, to assess the effects of different emission reduction strategies on microplastic inputs to rivers worldwide over the period 2010-2100, taking time steps of 10 years. We applied four scenarios: three focused on wastewater treatment technologies, ranging from high to low technology improvement levels, and one combining high technology in wastewater treatment with source-oriented measures. The results show that the combined strategy of high wastewater treatment and source-oriented measures is expected to be the most effective for reducing future microplastics in rivers on a global scale. By 2100, this combined strategy is expected to result in a 68% microplastic reduction in global rivers compared to 2010. African rivers will be the main hotspots, receiving more than five times more microplastics in 2100 than in 2010. In 2100, wear from car tires is expected to be the dominant source of microplastics globally. Our insights support the implementation of the European Green Deal and the realization of Sustainable Development Goal 6 (clean water).

Borax Cross-Linked Acrylamide-Grafted Starch Self-Healing Hydrogels.

The biocompatibility and renewability of starch-based hydrogels have made them popular for applications across various sectors. Their tendency to incur damage after repeated use limits their effectiveness in practical applications. Improving the mechanical properties and self-healing of hydrogels simultaneously remains a challenge. This study introduces a new self-healing hydrogel, synthesized by grafting acrylamide onto starch using ceric ammonium nitrate (CAN) as an initiator, followed by borax cross-linking. We systematically examined how the starch-to-monomer ratio, borax concentration, and CAN concentration impact the grafting reactions and overall performance of the hydrogels. The addition of borax significantly reinforced the strength of the hydrogel; the maximum storage modulus increased by 1.8 times. Thanks to dynamic borate ester and hydrogen bonding, the hydrogel demonstrated remarkable recovery properties and responsiveness to temperature. We expect that the present research could broaden the application of starch-based hydrogels in agriculture, sensors, and wastewater treatment.

A Multivariable Probability Density-Based Auto-Reconstruction Bi-LSTM Soft Sensor for Predicting Effluent BOD in Wastewater Treatment Plants

The precise detection of effluent biological oxygen demand (BOD) is crucial for the stable operation of wastewater treatment plants (WWTPs). However, existing detection methods struggle to meet the evolving drainage standards and management requirements. To address this issue, this paper proposed a multivariable probability density-based auto-reconstruction bidirectional long short-term memory (MPDAR-Bi-LSTM) soft sensor for predicting effluent BOD, enhancing the prediction accuracy and efficiency. Firstly, the selection of appropriate auxiliary variables for soft-sensor modeling is determined through the calculation of k-nearest-neighbor mutual information (KNN-MI) values between the global process variables and effluent BOD. Subsequently, considering the existence of strong interactions among different reaction tanks, a Bi-LSTM neural network prediction model is constructed with historical data. Then, a multivariate probability density-based auto-reconstruction (MPDAR) strategy is developed for adaptive updating of the prediction model, thereby enhancing its robustness. Finally, the effectiveness of the proposed soft sensor is demonstrated through experiments using the dataset from Benchmark Simulation Model No.1 (BSM1). The experimental results indicate that the proposed soft sensor not only outperforms some traditional models in terms of prediction performance but also excels in avoiding ineffective model reconstructions in scenarios involving complex dynamic wastewater treatment conditions.

Influence of Influent Load on Nitrification/Denitrification with MBBR for Oil Shale Retorting Wastewater Treatment: Performance and Microbial Community Structure

Influence of Influent Load on Nitrification/Denitrification with MBBR for Oil Shale Retorting Wastewater Treatment: Performance and Microbial Community Structure

Aluminum nanopowder from aluminum wastes recycling: a key additive for high-performance ZnO/ZnAl2O4 spinels in photocatalytic wastewater treatment

Aluminum nanopowder from aluminum wastes recycling: a key additive for high-performance ZnO/ZnAl2O4 spinels in photocatalytic wastewater treatment

Treated Wastewater by Selected Microalgae for Irrigation

Water is a major natural resource that supplies our demands in a precise manner. We must conserve and utilise every drop of water. Irrigation is considered the primary user of freshwater. Irrigation of land accounts for about 80% of overall freshwater usage. Reusing treated waste water could be an alternative method for increasing water resources. Many countries are using wastewater as an irrigation resource to meet urban demand and manage water scarcity. Microalgae-based water treatment is a viable bio refinery approach that promotes environmental and economic sustainability. Phycoremediation is a cost-effective, environmentally friendly, secure, and substitute method for wastewater treatment. In a polite lab experiment lasting 30 days, two microalgal strains Chlorella vulgaris and Trichormus variabilis were used as bioremediation agents for sewage water collected from Bahr El-Baqar, El- El-Sharkya Governorate, Egypt. The goal of the current study was to assess how inoculated microalgae (Chlorella vulgaris and Trichormus variabilis) contributed to the phycoremediation of sewage effluent, and then a pot experiment was conducted to test the water's potential for use in ornamental plant irrigation, due to decrease water consumption of fresh water. The study's findings revealed that sewage wastewater had a decrease in pH, electrical conductivity, total dissolved solids, phosphorous, potassium, ammonium, nitrate, biological oxygen demand, and chemical oxygen demand after 30 days of experimentation, some heavy metals were absorbed by both algal strains, while others were practically completely removed. Moreover, the treated waste water could be used for irrigation of ornamental plant.

Upgrading the eastern wastewater treatment plant effluent quality in Egypt for reuse by means of in-line coagulation followed by ultrafiltration

ABSTRACT Providing clean water to Egyptian citizens is one target of the 2030 sustainable development goals. Ultrafiltration (UF) has been investigated as an advanced treatment of the largest treatment plant in Alexandria. Although UF membranes have been widely used to treat secondary effluent, fouling remains a major challenge. The effects of green and conventional coagulants on controlling ultrafiltration fouling were examined. Two different dosages of each coagulant and a combination of ferric chloride and sodium ferrate were studied in a bench-scale setup that was built and operated under identical circumstances. The results showed that the combined ferrate and ferric chloride pretreatment had the highest performance in terms of the removal of organics and turbidity as well as the reduction of membrane fouling. Fouling can be managed in terms of the normalized flux drop with only 0.5 mg/L of ferrate, which performs similarly to 2.5 mg/L of ferric chloride. The higher the dosage of alum used, the lesser the fouling control observed. The green coagulant, when used as an in-line coagulant aid/oxidant with ferric chloride at very low doses, has a favorable potential to reduce membrane fouling and improve permeated wastewater quality, making it suitable for Grade A for reuse purposes.

Enhancing the anaerobic sludge characteristics and inorganic impurities removal from synthesis wastewater through integration of electrocoagulation process with up-flow anaerobic sludge blanket reactor.

The present study investigated effects of coupling electrocoagulation (EC) process with an anaerobic digestion bioreactor, namely up-flow anaerobic sludge blanket (UASB), for the synthetic wastewater treatment. The EC-UASB mode of operation consisted of one anode and two cathodes subjected to an intermittent electrical current (10 min ON/30 min OFF) with current density of 1.5 mA/cm2. In light of this integration, the concentration ofmixed liquor suspended solids and mixed liquor volatile suspended solids within anaerobic granular sludge (AGS) increased by 20.0 ± 1.4% and 12.8 ± 0.8%, respectively. The results of sludge volume index, loosely and tightly bound extracellular polymeric substances and their constituents (protein and carbohydrate) revealed that through this integration the quality of AGS has been improved. Furthermore, results of scanning electron microscopy and Fourier-transform infrared spectroscopy showed alteration in the morphology and functional groups of AGS, respectively. Additionally, this combination has demonstrated promising results in terms of performance improvement by increasing the removal efficiency of total dissolved solids by 12.1 ± 0.3% and reducing the ionic pollution in treated wastewater. However, the integration of the EC system within the UASB resulted in energy consumption and operating cost of 1.33 kWh/m3 and 0.099 USD/m3, respectively.

Effect of inorganic component of biochar on lead adsorption performance and the enhancement by MgO modification.

Biomass-derived biochar has enormous potential for sustainable and low-cost treatment of lead-contained wastewater. In this study, corncob and cow dung-derived biochar were prepared. The increase in pyrolysis temperature could improve the porous structures, surface area, functional groups and alkalinity, and further provide a higher Pb2+ capacity in both biochars. Cow dung biochar performed better than corncob for its higher inorganic mineral content and more alkaline surface. Among them, CDB-600 performed the Langmuir maximum capacity of 357.1 mg/g, with a high surface area of 144.3 m2/g; ion exchange and precipitate were the main adsorption mechanisms. After further MgO modification, the M-CDB displayed a high surface area of 166 m2/g, and ion exchangeability and precipitate-promoting effects were improved. M-CDB performed a Langmuir maximum capacity of 833.3 mg/g. The pHpzc was found to be 10 and the adsorbents portray a very good Pb2+ adsorption selectivity among coexisting ions in the solution. The adsorption process was found to be endothermic, feasible, spontaneous and chemisorption. The fixed lead on CDB-600 was stable in water. The immobilized lead could be desorbed by acid wash. CDB-600 performed better in terms of sustainability in use, which could support its continuous application ability.