Narrow Results

Organic dyes and heavy metals are renowned environmental contaminants due to their hazardous, long life time in the environment, and capability to accumulate into the human body. Most heavy metals are accumulated naturally, however only some are derived from anthropogenic sources. In the recent decades, metal organic framework (MOF) and their most fashionable derivatives are extensively examined to eradicate heavy metals and organic dye substances from polluted water as powerful adsorbent materials. MOFs have forever exposed attractive applications in adsorption technologies and membrane separation, among which water-stable MOFs are predominantly important in wastewater treatment (WWT) relevance. MOFs like metal-organic polymers, hybrid organic–inorganic materials, organic zeolite materials and coordination polymers have increased awareness and many of the MOFs have been synthesized to eradicate heavy metals and organic dyes from waste water, because of their outstanding characteristics like large surface area, stability, greater porosity which make the MOF a strong and powerful adsorbent. In this paper, we discussed about the removal of hazardous heavy metals and organic dyes using MOF materials and their analogues as strong adsorbents for contaminated waste water.

Industrial wastes are considered as critical factors for disturbing natural ecosystems. The East Calcutta Wetlands, a Ramsar site in West Bengal, India, receives composite industrial effluents, subsequently bringing various kinds of heavy metals throughout the year. This wastewater is being utilized by the local people for pisciculture. The present investigation was carried out to study 1) elemental distribution various components of the wetland and 2) potentiality of water hyacinth in metal amelioration. Water and sediments were collected from four different spots along a wastewater-carrying canal having a stretch of 40km from the source point to the final confluence with river and from the wastewater fed fishpond. Fish (three common carps viz. Labeo rohita, Cirrhinus mrigala and Oreochromis niloticus) and water hyacinth were collected from fishpond mentioned above. Samples were analyzed by PIXE with 3MeV tandem Pelletron. Cr, which is a known metal contaminant of tannery effluent, was detected along with S, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Zr. Variable concentrations of some elements like Ca, Fe, Zn in different fish organs was noted in the experiment. Accumulation of Cr, Cu from the water bodies by water hyacinth suggesting their crucial role in heavy metal amelioration.

The main purpose of this article is to apply response surface method to analyze the residual dyes removal independent variables from the experimental data for dye adsorption onto alkali-activated sand as natural adsorbent from textile wastewater. The independent variables are contact time (3–30min) and adsorbent dosage (12.5–100g) and the dependent variables are percentage of dye removal and dye adsorbed amount per alkali-activated sand as responses. The effect of the variables, their interaction with each other, the fitted model equations, the adequacy and desirability of the model was evaluated by RSM. Response surface method to analyze the residual dyes removal, which resulted in about 70% dye removal and 30 $\times 10^{-3}$mg/g dye adsorbed, with 0.983 of desirability for fitted model. Finally, the initial dye concentration effect was investigated.

TiO₂ film is prepared on the surface of Q235A substrate from an acid solution ($\mathrm{\text{pH}}=2$) to research its degradation of methylene blue organic pollutant in wastewater. The titanium oxysulfate is used as the titanium precursor to provide the source of titanium. The preparation of TiO₂ film is mainly a polymerization reaction of titanium oxysulfate, which makes Ti₂${\mathrm{\text{O}}}_5^{2+}$ and OH⁻ combine to produce [Ti₂O₅(OH)₂]_n precipitation deposited on the cathode surface by electrochemical reaction. TiO₂ film is formed after high temperature heating. The nitrate ion which derives from potassium nitrate in the electrolyte is reduced to hydroxide ion during the electrochemical reaction process, resulting in the formation of titanium compounds and titanium hydroxide. The TiO₂ film prepared from solution containing 0.2 mol/L KNO₃ has the best photocatalytic performance which can effectively degrade the methylene blue organic pollutant in wastewater. However, when the KNO₃ in the solution is 0.25 mol/L, excessive hydroxide ions inhibit the hydrolysis of titanium salts and accelerate the oxygen evolution resulting in the decrease of degradation efficiency.

Water Matters Engineering the Reclamation of H₂0.

Identification of Microbial Contamination in Water Treatment and Distribution Systems.

From Wastewater to Safe Water: The NTU Experience.

Second Generation Biofuels: The Way Forward.

The zinc oxide, silver particles and the nanocomposite Ag-ZnO were prepared in an easy, fast and environmentally friendly nanoscale method, where these nanomaterials were prepared from nitrates using plant leaf extract Albizia lebbeck, and this environmentally friendly method is safe, nontoxic and nonharmful to the environment, it is a system that is not only cost-effective, but also simple to use and efficient. The reduction reaction can regulate the features and qualities of the resultant chemicals. The researchers used a variety of methods to diagnose and investigate the properties of these nanomaterials, including scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). The results showed the formation of zinc oxide and silver in the form of nanoparticles with good properties, as well as the formation of the nanocomposite Ag-ZnO, and element analysis EDX, and infrared FT-IR, and the results showed the formation of zinc oxide and silver in the form of nanoparticles with good properties, and the results also showed the growth of Ag particles on the surface of the reduced zinc oxide and formation of nanocomposite Ag-ZnO. The photocatalytic degradation of Cibacron Brilliant Yellow 3G-P (CB) dye in the presence of visible light was investigated using Ag-ZnO nanostructures as a photocatalyst. About 1g/L of Ag-ZnO with 20ppm of the dye produces a greater efficiency in the photocatalysis of the dye in its aqueous solution. The influence of the catalyst amount was explored within the quantities (0.2–0.4–0.6–0.8–1.0–1.2–1.4g/L) of the components affecting the photo-smashing process to evaluate the best weight which was 1(g). A photosynthesis ratio was calculated using HCL and NaOH to modify the pH of solutions at a concentration of 5ppm, $\mathrm{\text{pH}}=2$, 4, 6, 8 and 10. It was also discovered that the acidic function 10 was the best function for breaking down the dye with a 99.1% success rate, and that the shattering reaction followed the kinetics of the first order (Pseudo first), with five consecutive reuses of the best catalyst agents in breaking down the dye Ag-ZnO, was also investigated. After 120min, Ag doping ZnO with 10% loading showed photocatalytic elimination of about 93%. and the impact of Ag-ZnO nanocomposite on Staphylococcus aureus and Escherichia coli bacteria was investigated, which were utilized as illustrative examples of the cream-negative bacterium and the positive bacteria, respectively. The findings indicated that the Ag-ZnO nanocomposite had a high rate of success in eradicating and destroying these germs, demonstrating the viability of using a nanoscale solution to sanitize and eradicate microorganisms.

In this study, the photocatalytic degradation of RhB dye in an aqueous solution using ZnO nanoparticles (NPs), $\gamma$-Fe₂O₃, $\gamma$-Fe₂O₃–ZnO, Ag–ZnO, and $\gamma$-Fe₂O₃–Ag–ZnO nanomaterials generated using poinciana leaf extract is presented. The nanomaterials were prepared utilizing environmentally friendly methods and poinciana leaf extract. The properties of the originally generated nanomaterials, analyzed through techniques such as atomic force microscopy (AFM), UV–visible spectroscopy, X-ray, electron microscopy, and FE-SEM, have been described. The hexagonal structure of ZnO wurtzite was also discovered to align with the XRD findings. Additionally, EDX mapping was employed to analyze the composition of the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite. A topological investigation confirmed the roughness of the created nanostructures. Regarding the photocatalytic Rhodamine B (RhB) dye degradation studies, the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite demonstrated superior performance compared to pure ZnO in breaking down dye molecules under visible light exposure. Employing an ideal configuration of 1.0 g/L of photocatalyst, pH 10, and 10 ppm of RhB, an impressive photodegradation effectiveness of nearly 99% was achieved in just 45 min of light exposure. An analysis of reactive species was conducted to determine the photodegradation efficiency of $\gamma$-Fe₂O₃–Ag–ZnO. To investigate the impact of the microorganisms Escherichia coli and Staphylococcus aureus on the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite, the results indicated that the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite achieved a high rate of success in neutralizing and eradicating these bacteria.

The United States (U.S.) environmental regulatory system relies heavily on self-reports to assess compliance among regulated facilities. However, the regulatory agencies have expressed concerns regarding the potential for fraud in self-reports and suggested that the likelihood of detection in the federal and state enforcement processes is low. In this paper, we apply Benford’s Law to three years of self-reported discharge parameters from wastewater treatment plant facilities in one U.S. state. We conclude that Benford’s Law alone may not be a reliable method for detecting potential data mishandling for individual facility–parameter combinations, but may provide information about the types of parameters most likely to be fraudulently reported and types of facilities most likely to do so. From a regulatory perspective, this information may help to prioritise potential fraud risks in self reporting and better direct limited resources.

Cadmium (Cd${}^{2+}$) is one of the toxic heavy metals that is frequently used in many industrial products. The wastewater from these industries and their products contains residual cadmium that are difficult to be removed economically from the effluent. Carbon nanotubes (CNTs) were synthesized in several batches and tested for their removal efficacy with regards to cadmium removal from synthetic wastewater. Fixed catalyst chemical vapor deposition (FCCVD) reactor system was fabricated in the laboratory for the synthesis of CNTs on the powdered activated carbons (PACs). The PACs were impregnated with Fe${}^{3+}$ catalysts, and growth parameters such as the reaction time, gas flow rates and reaction temperature were optimized. The sorption capacity of the raw CNT–PAC was not satisfactory until the sorbents were functionalized which eventually led to high adsorption capacities. The surface properties of CNT–PAC were modified by oxidative functionalization using two different methods: sonication with KMnO₄ and refluxing with HNO₃ at 140${}^{\circ }$C. KMnO₄-treated CNT–PAC exhibited the highest sorption capacity for cadmium uptake which increased from 4.77mg/g (untreated CNT–PAC) to 11.16mg/g; resulting in Cd${}^{2+}$ removal efficiency from 38.87% to 98.35%.

Tetracycline (TC) is a drug commonly detected in wastewater. Given this, researchers have been working intensely to create efficient methods to eliminate TC from water. Therefore, the work aimed to synthesize a metal-free catalyst, graphitic carbon nitride (g-CN), to remove TC from water through photocatalysis. The one-step methodology via thermal condensation successfully synthesized the catalyst. Also, a Box-Behnken experimental design was used in the TC treatment to optimize variables such as pollutant and catalyst concentration and pH. Under optimized conditions, there was a 79% removal in 2 h. Furthermore, the catalyst was reused in four consecutive cycles, demonstrating remarkable recyclability. Therefore, the catalyst produced proved effective and promising for the aqueous remediation of TC.

A coupled adsorption–desorption thermo-kinetic model is developed incorporating both adsorption and desorption reactions. A local pseudo-equilibrium condition at the interface of adsorbent and adsorbate bulk phases was used as isotherm equation which can even be applied for multi-pollutants scenarios. The developed model is then validated using collected experimental data of heavy metal ions (Pb, Cu, Cd, Zn, and Ni). Comparisons were made for a number of isotherm and kinetic models to examine the performance of the proposed model. The developed model revealed desirable accuracy and superiority over other models in predicting the adsorption behavior and can be used for other systems of concern. The model correlates the adsorption kinetic with an $R^2$ value of 0.9391 and desorption kinetic with an $R^2$ value of 0.9383. By application of the proposed model to any available adsorption datasets, the individual characteristics of adsorption and desorption can be determined.

New techniques and materials are called for wastewater treatment due to the shortage of worldwide fresh water and the increasing water demand. As a simple and efficient method, adsorption technique has been extensively applied to remove organic and inorganic pollutants from contaminated water. The application of carbon nanomaterials, such as activated carbon, carbon nanotubes (CNTs), graphenes and their derivatives/analogues, in wastewater treatment has also been investigated due to their unique properties, such as wide availability, porous structure, large surface area, tunable morphology and nontoxicity. This review highlights the recent advances of wastewater treatment utilizing carbon nanomaterial modified composites as adsorbents. The adsorption phenomenon and its mechanism are briefly discussed. Detailed discussions are focused on the selective adsorption of carbon nanomaterial composites to unique pollutants. The remaining challenges are also mentioned.

Semiconductor photocatalysis is considered one of the efficient and clean environmental technologies in the treatment of organic dye wastewater. Indium zinc sulfide (ZnIn₂S₄) is favored among many photocatalysts because of its narrow-forbidden bandwidth, good visible light absorption properties, suitable conduction and valence band positions, high chemical stability, low cost, easy preparation and low toxicity. However, indium zinc sulfide (ZnIn₂S₄) still faces the disadvantages of low visible light utilization and high photogenerated carrier complexation rate. In this paper, we introduce rare-earth ion doping and heterojunction of rare-earth oxides with ZnIn₂S₄ to improve photocatalytic efficiency, and we also review the current research status and development prospects of indium zinc sulfide in recent years.

Water system revenue losses, inefficiency, mismanagement, lack of productivity, and federal mandates are rapidly escalating the cost of water and wastewater for Baltimore consumers. Baltimore’s water and wastewater systems are municipally owned and poorly managed by Baltimore City. Due to a lack of maintenance, these systems are plagued by an immense number of leaks, main breaks, and sewage backups. In addition, the billing system has a long history of errors. The overall deterioration of the systems, inadequate capital management, and operational problems are symptomatic of the fact that the Baltimore City Department of Public Works lacks proper accounts, including a balance sheet. Despite these glaring flaws, the systems have been politicized and are now protected by an amendment to the Baltimore City Charter that prohibits the assistance of private enterprise and markets in addressing Baltimore’s endemic water and wastewater problems by tapping the competency and skills available in the private marketplace. In order to reverse the politicization of Baltimore’s water system, which will only make operation and capital mismanagement problems worse as well as increase costs for the citizens of Baltimore, the charter amendment must be eliminated, allowing for the private provision of infrastructure and its maintenance. We recommend that this private provision is based on the centuries-old tried and tested French model.

Using unique data on chemical manufacturing facilities regulated under the Clean Water Act (CWA), this paper analyzes the effect of one particular environmental management practice — internal monitoring — on regulated facilities’ compliance with wastewater discharge limits. To deepen our understanding of the role played by internal monitoring, we extend our analysis by exploring the interaction between internal monitoring and self-audits, which should share a similar purpose to internal monitoring by providing systematic information to regulated facilities on their pollution abatement efforts. Baseline empirical results robustly demonstrate that increases in the extent of internal monitoring significantly improve facilities’ environmental compliance. The extended empirical results offer moderate evidence that audits complement internal monitoring (and vice versa): as facilities audit more frequently, the productive effect of increased internal monitoring grows.

The Atlantic County Utilities Authority (ACUA), located in southern New Jersey, is responsible for treating and managing waste in Atlantic County. At both its solid waste facility (Egg Harbor Township) and wastewater treatment facility (Atlantic City), the ACUA has successfully implemented initiatives including renewable energy projects to reduce emissions. These projects have also saved the Authority money. ACUA’s ability to carry out these projects as a government entity demonstrate that opportunities are available for businesses of all types to have an impact.

Photodynamic therapy is a platform technology which uses a combination of a photosensitizer, light and molecular oxygen to achieve selective destruction of a biological target. This methodology is already in use for the inactivation of microorganisms but its application in wastewater disinfection is incipient. In this work we tested the effect of three solid matrixes with immobilized porphyrins in the photoinactivation of a sewage bacteriophage. The phage inactivation to the limits of detection (reductions of about 7 log) with one of the tested materials, means that this insoluble material can be applied in wastewater disinfection with the same efficacy of the non-immobilized photosensitizer. The complete eradication of viruses with low light intensity means that this technology can be applied to wastewater disinfection under natural irradiation conditions during all year, including the cloudy days of winter. In addition, this is an inexpensive and easily applicable methodology.

The ecology of municipal and industrial wastewater treatment is complex biocenoses. In fixed film systems or in suspended growth systems; besides, the bacterial consortium, several protozoan genera have been reported: testate amoebae, or organisms with a shell. Amoebae are commonly found in activated sludge systems. But just one or two genera have been reported. This study describes the protozoan ecology found in wastewater treatment systems with suspended and fixed biomass, fed with municipal and industrial wastewater (textile industry, dye process).

Amoebae are found various shapes and sizes (10 to 200 µm). Movement is due to cilia, pseudopodia or false feet, most of them reproduce asexually by cellular fission; they grow over organic particulate matter and tolerate low dissolve oxygen concentration. Amoebae are commonly found in treatment systems with nitrification and low organic load. They commonly eat bacteria, phytoplankton, particulate organic matter, cellulose and lignin. They are known as "panphytophagous", because they eat both detritus and living organisms. These characteristics allow these genera to treat water.

The most common genera found in biological wastewater treatment are: Arcella, Euglypha, Centropyxis, Trinema, Bullinularia and Diflugia.

Despite the treatment processes that a typical wastewater is subjected to, microorganisms present in the wastewater are not effectively removed. These pathogenic organisms play important roles in the spread of waterborne diseases. Important treatment process employed to destroy or inactivate these pathogenic microorganisms is called disinfection. Disinfection is an important application under chemical treatment process ofwastewater, which includes the use of chemical agents, such as compounds of chlorine, and/or nonchemical agents, such as heat, UV light, radiation, and mechanical means.

A compilation of general information available on existing international standards and studies on this issue is developed in this chapter.We performed a critical evaluation of technologies for wastewater treatment currently recommended for reuse in agricultural irrigation. The productive use of such treated water is an important alternative for agricultural irrigation because of its high content of nutrients and organic matter, which could facilitate an increase in crops and soil improvement.

The most widely recommended treatment technology is the stabilization lagoons, but it is also recognized that there are other available technologies and the need to consider a final stage of disinfection to achieve compliance of the international guidelines that regulate the wastewater quality for reuse. Ozonation of wastewater treatment is an attractive method due to its oxidative and bactericidal power, so its combination with other treatment processes such as coagulation– flocculation allows a considerable reduction of physicochemical and microbiological pollution of municipal wastewater, enabling its reuse in agricultural irrigation.