Water Pollution Problems Research Articles

Cobalt-Intercalated Birnessite-Type Manganese Oxide Catalysts for Low-Cost Cathodes in Microbial Fuel Cells

Microbial fuel cells (MFCs) are a promising technology for solving energy and water pollution problems. However, to promote the practical application of MFC, it is necessary to solve the problems of power output and electrode cost simultaneously. Therefore, transition metal-based catalysts that can improve air cathode functionality without using platinum catalysts, which are commonly used, are attracting attention. In this experiment, a cobalt-intercalated birnessite-type manganese oxide catalyst was used as the cathode of the MFC. In addition, rice husk charcoal from agricultural waste and Sumi ink were used as cathode materials to reduce cost and improve the physical stability of the electrodes. The conductivity of the Sumi ink is expected to compensate for the low conductivity of manganese oxide. The resulting power density was 5.8 times higher with the catalyst than without. It was also confirmed that the fabricated cathode operated for at least 90 days without maintenance.

Book Review of Modeling and Simulation of Environmental Systems:A Computation Approach

Water and air are important elements of the interactions that make up the environmental continuum, and these factors are critical to our lifestyles, economic well-being, and the health and integrity of ecosystems. With the development of advanced computational modelling, numerical techniques and fast computers, some complex environmental management problems can be solved by computational modelling. Modeling and Simulation of Environmental Systems: A Computation Approach is an English-language monograph in the field of modeling and simulation of environmental systems (published by CRC Press) , which is divided into four chapters, Water Resources, Air Pollution, Internet of Things and Environmental Systems, and Future Algorithms in Environmental Systems. Future Algorithms in Environmental Systems, presents four chapters on modeling and simulation of environmental systems and related case studies, covering computational methods used to solve air and water pollution problems, a general approach to spatio-temporal analytical modeling, the use of formulas, algorithms, and techniques to build mathematical modeling, and a pathway to the implementation of formulas for complex modeling problems. This paper briefly introduces the authors of the work, systematically sorts out the chapter structure of the book, and analyzes the application of some of the environmental models as well as the opportunities and challenges of using them. The work demonstrates how models, metrics, and ecological processes can be directly applied to environmental subdisciplines and can provide guidance and reference for environmental practitioners and research engineers.

Sea Urchin-like NiCo2O4 Catalyst Activated Peroxymonosulfate for Degradation of Phenol: Performance and Mechanism.

How to efficiently activate peroxymonosulfate (PMS) in a complex water matrix to degrade organic pollutants still needs greater efforts, and cobalt-based bimetallic nanomaterials are desirable catalysts. In this paper, sea urchin-like NiCo2O4 nanomaterials were successfully prepared and comprehensively characterized for their structural, morphological and chemical properties via techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), among others. The sea urchin-like NiCo2O4 nanomaterials exhibited remarkable catalytic performance in activating PMS to degrade phenol. Within the NiCo2O4/PMS system, the removal rate of phenol (50 mg L-1, 250 mL) reached 100% after 45 min, with a reaction rate constant k of 0.091 min-1, which was 1.4-times higher than that of the monometallic compound Co3O4/PMS system. The outstanding catalytic activity of sea urchin-like NiCo2O4 primarily arises from the synergistic effect between Ni and Co ions. Additionally, a comprehensive analysis of key parameters influencing the catalytic activity of the sea urchin-like NiCo2O4/PMS system, including reaction temperature, initial pH of solution, initial concentration, catalyst and PMS dosages and coexisting anions (HCO3-, Cl-, NO3- and humic acid), was conducted. Cycling experiments show that the material has good chemical stability. Electron paramagnetic resonance (EPR) and quenching experiments verified that both radical activation (SO4•-, •OH, O2•-) and nonradical activation (1O2) are present in the NiCo2O4/PMS system. Finally, the possible degradation pathways in the NiCo2O4/PMS system were proposed based on gas chromatography-mass spectrometry (GC-MS). Favorably, sea urchin-like NiCo2O4-activated PMS is a promising technology for environmental treatment and the remediation of phenol-induced water pollution problems.

Phytoremediation potential and its methods- a review.

With the increase in the world's population and the subsequent increase in housing density, we are facing the problem of water, soil, and air pollution. On the other hand, the use of physical environmental purification methods is very expensive and can even cause environmental pollution. Phytoremediation is a cheap and accessible method that uses the potential of plants to remove or destroy dangerous contaminants from water, soil, and air. One of the major problems in Phytoremediation is that the process is time-consuming. This can be overcome by adding compounds such as nanoparticles in order to increase the speed. Special care must be given to using the correct doses of nanoparticles because they pass through cells and biological membranes, which may cause contaminations. Therefore, the use of appropriate doses of nanoparticles will eventually accelerate the phytoremediation process. The purpose of this study is to assess the recent discoveries in the Phytoremediation process and its methods.

Hierarchical porous UiO-66 composites modified by dual competitive strategy for adsorption of oxytetracycline

Adsorption is a popular technology for solving water-pollution problems because it is highly efficient, affordable and environmentally friendly. In this study, a dual competition strategy was developed to improve oxytetracycline adsorption by modulating the UiO-66 defects. A series of defect-rich hierarchical porous UiO-66 was prepared using the competitive strategy of bi-metal (Zn2+/Zr4+) and bi-ligand (terephthalic acid/monocarboxylic acid). Compared with the pristine UiO-66, the defect-rich hierarchical porous UiO-66 has a higher adsorption efficiency and faster adsorption rate. Among them, the greatest adsorption ability of But-HP-UiO-66 was 209.97 mg∙g−1 at pH= 6.0, which was 9.89 times greater than UiO-66. The kinetic and isotherm fitting results showed that the adsorption was consistent with the Elovich and Freundlich models. According to the response surface model design based on four factors (OTC concentration, pH, humic acid and SO42- intensity), But-HP-UiO-66 exhibited an excellent adsorption effect and strong anti-jamming ability. The prominent advantages of this composite are its rich pore structure and abundant defects. The adsorption mechanism showed that the electrostatic interactions, metal-organic complexation, pore adsorption, hydrogen bonding and π-π interactions performed vital functions. This study provides a promising method for manufacturing strongly hierarchical porous MOFs and strengthens their potential applications in antibiotic elimination.

Advanced oxidation/reduction processes (AO/RPs) for wastewater treatment, current challenges, and future perspectives: a review.

Advanced oxidation/reduction processes (AO/RPs) are considered as effective water treatment technologies and thus could be used to solve the problem of water pollution. These technologies of wastewater treatment involve the production of highly reactive species such as •OH, H•, e-aq, SO4•-, and SO3•-. These radicals can attack the targeted contaminants present in aqueous media and result in their destruction. The efficiency of AO/RPs is highly affected by various operational parameters such as initial concentration of contaminant, solution pH, catalyst amount, intensity of light source, nature of oxidant and reductant used, and the presence of various ionic species in aquatic media. Among AO/RPs, the solar light-based AO/RPs are most widely used nowadays for contaminant removal from aqueous media because of their high environmental friendliness and cost effectiveness. By using these techniques, almost all types of pollutants can be easily removed from aquatic media within short intervals of time, and hence, the problem of water pollution can be solved effectively. This review focuses on various AO/RPs used for wastewater treatment. The effects of different operational parameters that affect the efficiency of these processes toward contaminant removal have been discussed. Besides, challenges and future recommendations are also briefly provided for the researchers in order to improve the efficiency of these processes.

Construction of robust DA@CNTs/CS hydrogel coatings on hydrophobic PVDF membrane by deposition of self-assembly for efficient separation of oil-water emulsion and dye wastewater

With the rapid development of industry, the problem of water pollution has become increasingly serious. Though there are many separation materials available to solve this problem, how to separate multiple wastewater at the same time remains a challenge. Hydrogel coating is suitable for use in the field of oil–water separation, and chitosan (CS) is effective in removing anionic dyes. Therefore, the preparation of separation membranes with hydrogel coating containing CS and dopamine (DA) can effectively separate oil–water emulsion and anionic dye wastewater. In this paper, DA@CNTs/CS hydrogel coating was prepared by sequentially coating Cu2+, DA@CNTs, Cu2+ and CS on the surface of polyvinylidene fluoride (PVDF) membrane by deposition of self-assembly, which enhanced the hydrophilicity of the membrane and made it highly underwater oleophobic and antifouling. The alkali treated PVDF membrane contained a large amount of –OH, Cu2+, which formed coordination bonds with –OH, CS, and DA and the hydrogel coating could be stably loaded on the membrane. In addition, the introduction of rigid CNTs effectively improved the performance of the modified membrane under extreme conditions such as high pH and high salt concentration. PVDF-DA@CNTs/CS membrane had an ideal pure water flux (PWF) of 1470 (L·m−2·h−1) and the separation efficiency of 99.7 % for anionic dye and 99.4 % for oil–water emulsion. The contaminant on the membrane surface can be quickly removed by washing with DI water. The overall performance of the membrane is also maintained at a very high level of long-term filtration of wastewater. In summary, this study provides a new approach to complex wastewater treatment technology.

Mechanism and Application of Constructed Wetlands in Sewage Treatment

In recent years, with the increasingly serious problem of global water pollution, constructed wetlands with high efficiency, high adaptability and low cost, as an effective wastewater treatment technology has been widely studied and applied. This article mainly introduced the common types of constructed wetlands, including surface flow constructed wetlands, subsurface flow constructed wetlands and a variety of composite constructed wetlands, and the mechanism of microorganisms, plants and substrates in constructed wetlands. Differently constructed wetlands are suitable for different scenes. It can be seen from the data that the constructed wetlands with different compositions have good effects on the removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH4+-N) in sewage. Microorganisms have good removal and transformation effects on nitrogen and phosphorus, and the application of biofilm technology also has good prospects and value. Plants can be used in the absorption and transformation of heavy metals. The adsorption of the matrix is mainly a physical process, which uses its loose porous and large specific surface area to adsorb pollutants. Artificial wetlands have a positive impact on sewage treatment and are conducive to the construction of ecological civilization.

Study on Parameter Inversion Model Construction and Evaluation Method of UAV Hyperspectral Urban Inland Water Pollution Dynamic Monitoring

The problem of environmental water pollution is becoming increasingly important. Inland rivers and lakes form interconnected water networks with fragile water ecosystems, and urban water pollution problems occur frequently. Chemical oxygen demand (COD), dissolved oxygen (DO), total phosphorus (TP), total nitrogen (TN), and ammonia nitrogen (NH3-N) in inland rivers are important indicators to evaluate water health quality. Timely and accurate reflection of dynamic changes to the key indices of urban river health status are of vital practical significance to adjust water treatment policy and ensure the stability of the aquatic environment and people’s health. This study used COD, DO, TP, TN and NH3-N as typical water quality parameters for a reservoir in Guangxi Province, China and established a set of standardized processes covering UAV hyperspectral sampling and ground spectral correction, spectral data preprocessing, and modeling. In combination with machine learning and statistical analysis, an inversion method for measuring urban inland water pollution from UAV hyperspectral imaging with different dynamic monitoring parameters was proposed. And we compared the different combinations of preprocessing algorithm-regression algorithm and dimensionality reduction algorithm to get a unified model for quantitative estimation of water quality parameter concentration. We evaluated the performance of the proposed model according to root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and coefficient of determination (R2). The experimental results showed that our model was superior to other algorithms in RMSE, MAE, MAPE, and R2. The MAPE of this model ranged from 0.01 to 0.12 and R2 ranged from 0.84 to 0.98 in all water quality parameters. In general, this study provides an effective tool for decision-makers to investigate the source and physical mechanism of water pollution and establish a graded water quality evaluation model.

Eco-friendly and multifunctional superhydrophilic and underwater superoleophobic materials with adsorption, photodegradation and oil-water separation properties

The frequent water pollution problems have caused serious harm to the ecological environment and human health, among which, a large number of waste water contains heavy metal ions, organic dyes, oil-water emulsion and other pollutants. Therefore, it is particularly important to prepare multifunctional materials that can separate these pollutants and purify wastewater. In this paper, ovalbumin (OVA), phytic acid (PA) and egg shell powder (ESP) and TiO2 particles were used to construct a composite system, which was loaded on fabric, cotton and PVDF membrane by impregnation method. The preparation of OVA-ESP-TiO2-PA modified materials which can efficiently separate various oil-water mixtures and oil-water emulsions were successfully achieved. The modified material could achieve high flux (up to13458 L m−2h−1) and separation efficiency (＞99 %) for various mixtures of oil and water by gravity-driven. Typically, it shows good stability and durability under strong acid and alkali (pH=1–12) and different temperatures (T = 10–60 ℃), and can be reused. What's more, the modified materials can effectively adsorb organic dyes (＞92 %) and heavy metal ions (up to 85 %) and can degrade organic dyes by ultraviolet light. It provides a new idea for the separation of oil-water mixture and the purification of waste liquid containing organic dyes and heavy metal ions, which has a good application prospect in the treatment of industrial wastewater and domestic wastewater.

Spatial confinement-regulated peroxymonosulfate activation to boost the generation of high-valent cobalt and radical species for achieving rapid removal of organic pollutants

It is of great significance to establish simple and effective methods to tackle water pollution problems. Herein, Co-loaded hollow carbon sphere (namely Co-HCS-1) served as PMS activation mediator was synthesized. The construction of hollow structure can improve specific surface areas and offer more active sites, thereby reducing electron transfer resistance and increasing contact among PMS, pollutant and catalyst. Hence, the Co-HCS-1-mediated direct electron-transfer oxidation between PMS and pollutant was enhanced. After embedding Co-based catalyst in the shell of hollow carbon sphere, hollow carbon shell will provide spatial confinement for Co-based catalyst, which shortened mass transfer process. Thus, spatial confinement effect originating from carbon sphere can accelerate the charge transfer between PMS and active sites of Co-HCS-1, thereby promoting O-O bond cleavage of PMS. As a result, the generations of radicals and high-valent metal complexes (namely Co-HCS-1≡Co4+) were boosted. Under the combined effects of electron-transfer oxidation, reactive oxygen species and Co-HCS-1≡Co4+, more than 90 % of typical organic pollutants can be removed from simulated wastewater within 5 min by Co-HCS-1/PMS system, and a high removal efficiency of total organic carbon can also be realized. To sum up, current work provided a valuable reference for the preparation and application of catalyst with high activity in PMS activation.

A Co3O4-x/Co nanocomposite with synergistically enhanced electrochemical activity for reduction of nitrite to ammonia

Electrocatalytic reduction of nitrite (NO2−) to ammonia (NH3) cannot only solve the problem of water pollution, but also produce high value-added ammonia. In practical applications, it is extremely important to develop high performance and cheap electrocatalysts. In this paper, a nano-electrocatalyst (Co3O4-x/Co) was prepared by combining cobalt trioxide (Co3O4-x) with cobalt nanoparticle (Co). The Co3O4-x is rich in oxygen vacancy. In neutral electrolyte, the composite electrocatalyst shows superior electrocatalytic activity for NO2− reduction to ammonia (Faraday efficiency up to 97 % at -0.8 V vs. RHE, ammonia yield up to 0.628 mmol h−1 cm−2 at -1.1 V vs. RHE). This performance may result from synergistic enhancement between Co3O4-x and Co.

Application of Molybdenum Disulfide Nanomaterials in Wastewater Treatment

The problem of global water pollution is becoming increasingly serious, especially in industrial wastewater from industries such as textiles and printing, which contains a large amount of toxic and harmful organic dyes, causing serious water pollution problems. It is urgent to remove organic dyes from wastewater and improve the quality of water resources. In wastewater treatment, adsorption is considered the most convenient, economical, and efficient method for treating dye wastewater, and can be used in large-scale production. Molybdenum disulfide nanomaterials have attracted the attention of researchers, especially in the field of wastewater treatment, due to their unique physical, chemical, electrical, biological, and mechanical properties.

Analisis Kitin dari Cangkang Kepiting Rajungan (Portunus pelagicus)

Crab skin is a processing waste that reaches 50-60% by weight intact, with a chitin content of 20-30%. If this waste can be utilized, then in addition to overcoming the problem of water pollution, it will also provide added value to the fisheries processing business. Until now, the use of these wastes is still very limited. Its use includes making petis, shrimp paste, flavor, and as a feed ingredient. This research is about the isolation of chitin from crab shell shells through the stages of demineralization and deproteination. The research method used in this study has 2 stages, namely deproteination with variations in NaOH reagent concentrations of 3.5%, 45.0%, 5 and 6.5%, and demineralization with HCl reagent concentrations of 1 M. Test characteristics of chitin and chitosan isolated results carried out with IR. The results of data analysis showed that the isolation of chitin from crab shells went through several stages, namely two stages of deproteination and demineralization stages. The optimum concentration of NaOH reagents used in the deproteination process is 4.50% with the concentration of protein that can be released in the first test of 18.0467 gr and in the second test of 17.8445 gr. The optimum concentration of HCl reagent used in the demineralization stage is 0.1 N. The optimum incubation time for the chemical deproteinas stage i is 2 hours with chitin levels produced of 32.8320 gr

Perception of water pollution among Malaysian university students: A case study

<p>The present study aimed to understand the perception and knowledge of university students toward water pollution. In the present study, demographic profile, knowledge of water pollution, university students’ perception of water pollution and attitudes towards water pollution prevention were included in the survey questions. This survey on water pollution was conducted among a diverse group of Malaysian university students using Google Forms. The results showed that almost 50% of the respondents have basic knowledge of water pollution, and agreed that industrial activities were the main factor causing water pollution in Malaysia, followed by the accumulation of organic chemical wastes and heavy metals accumulation. It was also revealed that have shown that the water pollution campaign was a key factor to spread awareness among Malaysians and increase knowledge about water pollution problems. The results further confirmed that water pollution needs to be aware of, which showed that respondents were well aware of the water pollution issue in Malaysia and felt obligated to spread awareness and take action towards water pollution regardless of their surrounding community.</p>

Study on mechanical properties of coal gangue and fly ash mixture as backfill material based on fractal characteristics.

Backfill mining can effectively alleviate the problems of surface collapse and ecological water pollution, in which the mechanical properties of backfill materials, including coal gangue and coal fly ash, have a decisive role in the effect of filling mining. In this study, we analyze the permeability characteristics of coal gangue filler through a set of homemade percolation test systems and introduce fractal characteristics to investigate the key factors affecting percolation in complex pores of broken coal gangue. The results indicate that the fractal dimensions of crushed coal gangue particles show an increasing trend with increasing axial loading and that the variation range is from 2.15647 to 2.58933. The coal fly ash concentration has a positive relationship with the acceleration factor. The permeability of crushed coal gangue follows a hierarchical distribution law and the permeability changes in the magnitude range of 10-11 ~ 10-9 m2. The fractal dimension is inversely related to the permeability of crushed coal gangue. The experimental results show that the coal gangue will be further crushed and that adding a certain concentration of coal fly ash can achieve a better water barrier, which provides theoretical support and engineering significance for the stability analysis of geological engineering and backfill mining technology.

A holistic approach to the spatio-temporal variability investigation of the main river water quality – The importance of tributaries

The surface water pollution can cause serious ecological disasters. An example is large-scale fish deaths due to excessive salinity, which is global problem. In order to prevent such situations, it is necessary to carry out regular monitoring of both main rivers and their tributaries. The current monitoring system is neither adapted to the variability associated with the diversified use of catchments nor to changing climatic conditions. The Bzura River is one of the most anthropogenically transformed Polish rivers. So far, no comprehensive assessment of the chemical status of its catchment has been carried out. The presented research is a continuation of the study of the spatio-temporal variability of the Bzura chemistry. It covered 19 tributaries within the boundaries of the Łódź Voivodeship. Samples were collected once a month for one hydrological year. In total, 228 samples were obtained, in which 21 parameters were measured. Spatio-temporal variability of water quality on the basis of coefficients of variation (CVs) and water quality indices (WQIs) was evaluated. Principal component analysis (PCA) and cluster analysis (CA) were also performed. In addition, the datasets were visualized using geochemical maps. Combined monitoring with geospatial analysis brings benefits in terms of efficient control and management of water resources. The tributaries were divided according to the degree of their pollution. It was found that the electrical conductivity and concentrations of dissolved oxygen, nitrates, calcium and magnesium differentiated the tributaries in terms of pollution the most. The strong salinity from agricultural and geogenic sources was found. The WQIs were higher for the tributaries than for the Bzura. It suggests that the Bzura may be polluted by the tributaries under “favorable” climatic and hydrological conditions. Therefore, smaller watercourses should be included in monitoring and become more important in terms of an effective solution to global problem of surface water pollution.

Degradation of bisphenol A by persulfate activation of MoS2 composite iron tailings.

In this paper, molybdenum disulfide was grown on the surface of iron-containing tailings by hydrothermal method, and a series of highly efficient activated persulfate (PMS) iron-based catalysts were successfully prepared. The results show that in the CTM 1-200/PMS system, the additional ratio of tailings and the hydrothermal temperature have important effects on the catalyst. The catalyst prepared under the conditions of CT:MoS2 (molar ratio 1:1) and hydrothermal temperature of 200 °C (CTM 1-200) had the best degradation effect on BPA, and the degradation effect was increased by four times. The reason for the improvement of degradation efficiency is that the introduction of MoS2 accelerates the REDOX cycle between Fe(II)/Fe(III), and the reduction of Fe(III) is mainly related to Mo(IV), while the reduction capacity of S is relatively weak. Molybdenum disulfide/iron tailing composite material provides a way for tailings to solve the problem of water pollution.

Comparing removal of synthetic anthraquinone dye wastewater in an electrical discharge and UV-LED/WO3 reactors: using statistical Taguchi optimization approach.

Advanced oxidation processes (AOPs) are an available solution for the rapid growth of the water pollution problem. In the present study, the process of UV-LED/WO3 and plasma was comparatively studied to remove reactive blue 19. The photocatalyst process efficiency was analyzed by statistical Taguchi model. The effect of experimental variables of contact time, pH, catalyst dosage, and pollutant dosage was investigated and found that the model is able to explain the process due to the high value of R > 95%, and the optimum condition was at 10 mg/L of dye concentration, 1g/L of catalyst, and 180 min of detention time in which over 75% of degradation was achieved. Based on the model, the more reaction time would increase the reactor performance, while further excessive increase of catalyst dosage over 1 g/L would deteriorate the performance. Obviously, the least amount of pollutant is the most favorable for the treatment reactor. Using plasma process for dye degradation was the next step of the research. Accordingly, the removal rate achieved over 90% of 10 mg/L of initial industrial dye in durational time of 4 min, input voltage 13.5 kV, and pH = 2. The results showed the higher oxidizing capacity of plasma than the conventional photocatalyst process.

Construction of a biomimetic wood structure with cellulose nanofiber/molybdenum disulfide hybrid aerogel for highly-efficient solar-driven interfacial evaporation

Solar-driven interfacial water evaporation is a promising solution to water scarcity and pollution problems because it can efficiently convert solar energy into thermal energy and produce sustainable clean water. In this work, inspired by the multi-channel structure in the xylem of plants, cellulose nanofibers (CNF) and molybdenum disulfide (MoS2) nanosheets were selected to construct CNF/MoS2 nanosheets aerogel (CMoA) with vertical pores by directional freeze-drying method. Then we utilized the aerogel as an interfacial solar evaporator. The super-hydrophilic and internal vertical pore structure of this evaporator gives CMoA a high capacity to store and transport water, with a water evaporation rate of 1.81 ± 0.06 kg·m−2·h−1 under 1 sun. The vertical pore structure and the strong ability to transport water of the evaporator also enable the salt on the evaporator surface to diffuse into the bulk water in time, without causing salt deposition. Therefore, CMoA has high salt resistance and stability and can achieve fast evaporation even in high-concentration salt water. In addition, CMoA can also produce water at a rate of up to 10.3 kg·m−2 per day in the outdoor environment. By combining the natural bio-based material CNF with the biomimetic wood structure of aerogel, CMoA has a facile water transport process similar to that of plants. Moreover, our CMoA is a monolayer structure, which makes the preparation process simple and less costly. These multiple advantages make CMoA a promising application for future practical desalination work.