Conventional Water Treatment Techniques Research Articles

Biodegradation of the cyanobacterial toxin anatoxin-a by a Bacillus subtilis strain isolated from a eutrophic lake in Saudi Arabia.

Anatoxin-a (ATX-a) is a neurotoxin produced by some species of cyanobacteria. Due to its water solubility and stability in natural water, it could pose health risks to human, animals, and plants. Conventional water treatment techniques are not only insufficient for the removal of ATX-a, but they also result in cell lysis and toxin release. The elimination of this toxin through biodegradation may be a promising strategy. This study examines for the first time the biodegradation of ATX-a to a non-toxic metabolite (Epoxy-ATX-a) by a strain of Bacillus that has a history of dealing with toxic cyanobacteria in a eutrophic lake. The Bacillus strain AMRI-03 thrived without lag phase in a lake water containing ATX-a. The strain displayed fast degradation of ATX-a, depending on initial toxin concentration. At the highest initial concentrations (50 & 100µg L- 1), total ATX-a degradation took place in 4 days, but it took 6 & 7 days at lower concentrations (20, 10, and 1µg L- 1, respectively). The ATX-a biodegradation rate was also influenced by the initial toxin concentration, reaching its maximum value (12.5µg L- 1 day- 1) at the highest initial toxin concentrations (50 & 100µg L- 1). Temperature and pH also had an impact on the rate of ATX-a biodegradation, with the highest rates occurring at 25 and 30 ºC and pH 7 and 8. This nontoxic bacterial strain could be immobilized within a biofilm on sand filters and/or sludge for the degradation and removal of ATX-a and other cyanotoxins during water treatment processes, following the establishment of mesocosm experiments to assess the potential effects of this bacterium on water quality.

A Review on Various Bio-Resources as a Tool to Reduce Water Pollution Via Eco-Friendly Adsorption Technology

Pollution of water bodies is a raising concern in today’s world. Water pollution occurs when harmful compounds enter water bodies and lowers the water quality. It is necessary to treat wastewater before its final disposal into aquatic bodies and environment. Among all the conventional water treatment techniques, adsorption technology attracted much attention owing to its simplicity and eco-friendly nature. Several studies were reported with the application of different kinds of adsorbents in the treatment of both organic and inorganic pollutants in wastewater. However, demand for the development of more suitable adsorbent with selective pollutant removal capacity and good economic feasibility is still rising. Therefore, this review aims to provide a detailed review about the adsorption technology and its mechanisms in pollutant removal process. The adsorption ability of certain important adsorbents were discussed along with future perspectives. Effective, economical, and environmentally friendly wastewater management should be the ultimate objective of any wastewater treatment process. Keeping that in view, this review article highlighted the importance of wastewater management and treatment via adsorption technology.

Leveraging ChatGPT and Bard: What does it convey for water treatment/desalination and harvesting sectors?

Artificial intelligence (AI) has emerged as a prominent tool in the modern day. The utilization of AI and advanced language models such as chat generative pre-trained transformer (ChatGPT) and Bard is not only innovative but also crucial for handling challenges related to water research. ChatGPT is an AI chatbot that uses natural language processing to create humanlike conversations. ChatGPT has recently gained considerable public interest, owing to its unique ability to simplify tasks from various backgrounds. Similarly, Google introduced Bard, an AI-powered chatbot to simulate human conversations. Herein, we investigated how ChatGPT and Bard (AI powdered chatbots) tools can impact water research through interactive sessions. Typically, ChatGPT and Bard offer significant benefits to various fields, including research, education, scientific publications, and outreach. ChatGPT and Bard simplify complex and challenging tasks. For instance, 50 important questions about water treatment/desalination techniques and 50 questions about water harvesting techniques were provided to both chatbots. Time analytics was performed by ChatGPT 3.5, and Bard was used to generate full responses. In particular, the effectiveness of this emerging tool for research purposes in the field of conventional water treatment techniques, advanced water treatment techniques, membrane technology and seawater desalination has been thoroughly demonstrated. Moreover, potential pitfalls and challenges were also highlighted. Thus, sharing these experiences may encourage the effective and responsible use of Bard and ChatGPT in research purposes. Finally, the responses were compared from the perspective of an expert. Although ChatGPT and Bard possess huge benefits, there are several issues, which are discussed in this study. Based on this study, we can compare the abilities of artificial intelligence and human intelligence in water sector research.

Biotechnological advancements towards water, food and medical healthcare: A review

The global health status is highly affected by the growing pace of urbanization, new lifestyles, climate changes, and resource exploitation. Modern technologies pave a promising way to deal with severe concerns toward sustainable development. Herein, we provided a comprehensive review of some popular biotechnological advancements regarding the progress achieved in water, food, and medicine, as the most substantial fields related to public health. The emergence of novel organic/inorganic materials has brought about significant improvement in conventional water treatment techniques, anti-fouling approaches, anti-microbial agents, food processing, biosensors, drug delivery systems, and implants. Particularly, a growing interest has been devoted to nanomaterials and their application for developing novel structures or improving the characteristics of standard components. Also, bioinspired materials have been widely used to improve the performance, efficiency, accuracy, stability, safety, and cost-effectiveness of traditional systems. On the other side, the fabrication of innovative devices for precisely monitoring and managing various ecosystem and human health issues is of great importance. Above all, exceptional advancements in designing ion-selective electrodes (ISEs), microelectromechanical systems (MEMs), and implantable medical devices have altered the future landscape of environmental and biomedical research. This review paper aimed to shed light on the wide-ranging materials and devices that have been developed for health applications and mainly focused on the impact of nanotechnology in this field.

Fixed Bed Column Adsorption Studies of selected Phenols and Dyes using Low-cost adsorbents. A mini Review

Consumption of water contaminated with dyes and phenolic compounds is detrimental to human and animal wellbeing even at permissible limits. Therefore, their decontamination from water is important for the safety of consumers. Conventional water treatment techniques such as ozonation, ion exchange among others are expensive and ineffective. Adsorption as an emerging technique has gained research interest because of its ease in design, environmentally friendly and availability of materials as adsorbents in large quantities. The application of various adsorbents have extensively been reported for decontamination of dyes and phenolic compounds in wastewater such as 4-chlorophenol, Metanil Yellow (MY) dye, Phenol, Methyl green dye, Bromothymol Blue dye, Crystal violet, Methylene blue and Direct Blue 71. It has also been reported that adsorption by column continuous processes are more efficient than batch as it can be used continuously under high effluent flow rates in many pollution control processes in an industrial set up. The fixed bed column adsorption data is analyzed at different column conditions of bed height, pH, particle size, concentration and flow rate using different kinetic models such as Bohart-Adams, Thomas, Yoon-Nelson, Clark, Bed depth service time and Wolborska models amongst others to determine the column performance. The present paper involves a mini review of dynamics of fixed-bed column studies for removal of selected dyes and phenolics from a synthetic media.

Effectiveness of Non-Thermal Plasma Induced Degradation of Per- and Polyfluoroalkyl Substances from Water

Per- and polyfluoroalkyl substances (PFAS) are omnipresent synthetic chemicals. Due to their industrial importance and widespread use as a key component in various applications and a variety of products, these compounds can be found today in high concentrations (>1 μg/L) in surface and groundwater but also spread throughout the ecosystem, where they represent a serious threat to most living organisms. The removal or degradation of PFAS contaminants from water and soil is becoming a legal obligation in a growing number of countries around the globe. This, however, demands novel techniques for the degradation of PFAS since conventional water treatment techniques are either insufficient or extremely expensive due to the persistent nature of these compounds caused by their extraordinary chemical stability. The goal of this work was therefore to investigate the practical potential of the application-oriented use of atmospheric non-thermal plasma as a powerful advanced oxidation method for the purification of water contaminated with PFAS compounds. Special attention was devoted to the development of the concept that can be scaled up to the capacity level of approximately 100–200 m3 of water per hour, contaminated with PFAS and other contaminants including organic and inorganic material generally present in soil, and surface or groundwater. Our major research interest was to define the minimum required treatment time for optimal purification results, as well as to understand the influence of the initial concentration of PFAS in water and the potential presence of co-contaminants often present in situ on the efficiency of the degradation process. A chemical analysis of the treated samples demonstrated the ability of the atmospheric plasma to reduce more than 50% of the initial PFAS amount in the water samples in less than 300 s of treatment time. PFOA, however, showed more rigidity towards degradation, where a double treatment time was needed to reach similar degradation levels. The obtained results showed that the initial concentration level does not play a major role in the process. However, the PFAS degradation profiles for all tested concentrations show a strongly nonlinear behavior with time, characterized by the fast decrease of the process efficiency in the case of longer treatment times. For prolonged treatment times, a constant increase in the samples’ conductivity was measured, which might be the limiting factor for the degradation rate in the case of prolonged treatment times.

Adsorption and photocatalytic removal of Rhodamine B from wastewater using carbon-based materials

The removal of Rhodamine B dyes (RhB) from wastewater, using the conventional water treatment techniques, usually involves some challenging processes. This is challenging because RhB is a highly soluble and persistent dye found in wastewater. Although some efficient physiochemical techniques have been reported, the limitations associated with these technologies, such as the production of secondary wastes in the chemical precipitation process, cannot be overlooked. Photocatalysis, on the other hand, could transform the dye molecules to less toxic or non-toxic final products without the generation of secondary wastes. Therefore, the combined use of photocatalysis and adsorption processes for the removal of RhB from water has been found to be highly efficient. However, the development of materials that possess efficient adsorption and photocatalytic properties remains a major challenge since most of the known materials have a low adsorption capacity and may not be photostable. Carbon-based materials have been used as an efficient material for the removal of RhB from wastewater due to their high adsorption capacity and light-sensitive properties. In this report, the properties, synthesis and use of the carbon-based materials for the removal of RhB from wastewater are discussed in detail. Different factors that affect the removal of RhB dyes from wastewater and the mechanism of photocatalysis and adsorption isotherms are critically reviewed. Furthermore, limitations of carbon-based materials as both adsorbents and photocatalysts are presented, and the possible methods for overcoming these limitations are also investigated.

Recent development in antimicrobial activity of biopolymer-inorganic nanoparticle composites with water disinfection potential: a comprehensive review.

Nowadays, water-borne diseases including hepatitis remain the critical health challenge due to the inadequate supply of potable and safe water for human activities. The major cause is that the pathogenic microorganisms causing diseases have developed resistance against common techniques used by sewage water treatment plants for water disinfection. Therefore, there is a need to improve these conventional water treatment techniques by taking into consideration the application of nanotechnology for wastewater purification. The main aim of this paper is to provide a review on the synthesis of biopolymer-inorganic nanoparticle composites (BINCs), their used as antimicrobial compounds for water disinfection, as well as to elaborate on their antimicrobial mechanism of action. The microbial properties affecting the activity of antimicrobial compounds are also evaluated.

Efficacy and mechanism of chemical-free VUV/UV process for oxytetracycline degradation: Continuous-flow experiment and CFD modeling

Eliminating tetracycline antibiotics from waste streams by conventional water treatment techniques remains challenging. Vacuum-ultraviolet/ultraviolet (VUV/UV)-based advanced oxidation technique is a promising, environment-friendly alternative to remove micropollutants from wastewater without adding chemicals. This study carried out flow-through experiments and numerical modeling to determine the efficiency and mechanism of VUV/UV process in degrading oxytetracycline (OTC) via a newly developed photoreactor with tangential inlet and outlet. OTC degradation pathway and reaction rate constant were identified through semi-batch experiments at various initial OTC concentrations in different water matrices. The decomposition of OTC by the VUV/UV process was as effective as that by the H2O2/UV approach but generated less byproducts and thus could be beneficial for process control. Removal of organic matter and inorganic ions were suggested before VUV/UV process to improve the treatment efficiency. Flow characteristics simulated by computational fluid dynamics (CFD) revealed that a special bidirectional spiral flow was formed in the new reactor, which improved the mixing efficiency of fluids and thus enhanced the contact between hydroxyl radicals and the contaminant. The distribution profiles of OTC and hydroxyl radicals confirmed that the target contaminant was decomposed following the flow direction, and the degradation efficiency could be further increased by decreasing the internal diameter of the photoreactor. The electrical energy-per-order analysis of the photoreactor proved the high-energy utilization efficiency and cost-effectiveness of the VUV/UV process.

Evaluation of amicarbazone toxicity removal through degradation processes based on hydroxyl and sulfate radicals

The herbicide amicarbazone (AMZ), which appeared as a possible alternative to atrazine, presents moderate environmental persistence and is unlikely to be removed by conventional water treatment techniques. Advanced oxidation processes (AOPs) driven by •OH and/or SO4•− radicals are then promising alternatives to AMZ-contaminated waters remediation, even though, in some cases, they can originate more toxic degradation products than the parent-compound. Therefore, assessing treated solutions toxicity prior to disposal is of extreme importance. In this study, the toxicity of AMZ solutions, before and after treatment with different •OH-driven and SO4•−-driven AOPs, was evaluated for five different microorganisms: Vibrio fischeri, Chlorella vulgaris, Tetrahymena thermophila, Escherichia coli, and Bacillus subtilis. In general, the toxic response of AMZ was greatly affected by the addition of reactants, especially when persulfate (PS) and/or Fe(III)-carboxylate complexes were added. The modifications of this response after treatment were correlated with AMZ intermediates, which were identified by mass spectrometry. Thus, low molecular weight by-products, resulting from fast degradation kinetics, were associated with increased toxicity to bacteria and trophic effects to microalgae. These observations were compared with toxicological predictions given by a Structure-Activity Relationships software, which revealed to be fairly compatible with our empirical findings.

Application of response surface methodology for the optimization of polycyclic aromatic hydrocarbons degradation from potable water using photo-Fenton oxidation process

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds, composed of benzene rings. The objective of this research was to identify the optimum condition for the degradation of PAHs contaminated water using photo-Fenton oxidation process via response surface methodology (RSM). Aqueous solution was prepared and potable water samples were collected from water treatment plants in Perak Tengah, Perak, Malaysia in September 2016. The reaction time, pH, molarity of H2O2 and FeSO4 were analyzed followed by RSM using aqueous solution. A five level central composite design with quadratic model was used to evaluate the effects and interactions of these parameters. The response variable was the percentage of total organic carbon (TOC) removal. PAHs quantification was done using gas chromatography mass spectrometry analysis. The regression line fitted well with the data with R2 value of 0.9757. The lack of fit test gives the highest value of Sum of Squares (15,666.64) with probability F value 0.0001 showing significant quadratic model. The optimum conditions were established corresponding to the percentage of TOC removal. The PAHs removal efficiency for potable water samples ranged from 76.4% to 91% following the first order of kinetic rates with R2 values of >0.95. Conventional water treatment techniques are not effective for PAHs removal. Thus, advanced oxidation processes may be considered as an alternative to conventional water treatment techniques in Malaysia and other developing countries.

Removal of Diuron and Hexazinone from Public Water Supply Using a Filter System

ABSTRACT: The intensive use of pesticides, such as the herbicides diuron and hexazinone, leads to a concern about the preservation of the water quality of the water resources destined for human consumption. Currently, conventional water treatment techniques do not have high capacity to remove herbicides; therefore, the need to study other techniques arises. The present study aimed to evaluate the efficiency of the removal of diuron and hexazinone herbicides present in water through a commercial filtration system. The study was carried out in a filtration system composed of the following sequence of filters: sand filter and coconut shell activated granular carbon, polypropylene filter 20 mm, activated carbon filter with silver salts, polypropylene filter 5 mm and reverse osmosis. The affluent contained an initial concentration of 12.06 mg mL-1 of hexazinone and 37.70 mg mL-1 of diuron. The samples were collected in all filters and subjected to the analysis of turbidity and presence of herbicides by high performance liquid chromatography. The filter set removed 99.31; 99.84 and 99.99% of water turbidity, hexazinone and diuron respectively at the end of the system. After the filtration process, the treated water presented adequate quality for public supply and human consumption. The technique employed in this study is easy to operate and has a low acquisition and maintenance cost.

Biosorption of lead(II) by chemically modified Mangifera indica seed shells: Adsorbent preparation, characterization and performance assessment

Abstract In the wake of rising demand for water as well as widespread unavailability of resources for employment of conventional water treatment techniques, the use of adsorption involving agricultural waste derived biosorbents has become a desired alternative. However, in their natural state, these agro-biosorbents exhibit low sorption capacity thereby raising the need for physical and/or chemical modification for improvement. Mangifera indica (mango) seed shell powder was modified by treatment with sodium hydroxide solution followed by surface functionalization with ethylenediaminetetraacetic (EDTA) dianhydride. The natural and modified mango materials were characterized by Fourier transform infra-red spectroscopy (FTIR), elemental, thermogravimetric and X-ray diffraction analysis. The performance of the carboxyl functionalized mango biosorbent (CFMS) was tested against that of the alkali treated mango biosorbent (ATMS) for removal of lead(II) ions from aqueous solutions through batch adsorption experiments. Binding mechanism elucidation through FTIR and thermogravimetric analysis demonstrated chelation by the grafted EDTA ligands. The effects of contact time and initial lead(II) ion concentration were evaluated. The Langmuir, Freundlich and Dubinin–Radushkevich models were used to study the adsorption isotherms while the pseudo-first order, pseudo-second order, Elovich, Bangham’s and intra-particle diffusion models were used for the simulation of sorption kinetics. The isotherms were best simulated by the Langmuir model and the adsorption capacity of ATMS was 59.25 mg g−1 whereas that of CFMS was 306.33 mg g−1. Sorption kinetics were well simulated by the pseudo-second order model.

Treatment of nanofiltration membrane concentrates: Organic micropollutant and NOM removal

In the Nanofi ltration (NF) membrane systems utilised for river water treatment for drinking water production purposes, 15–25 % of the feed is rejected by the membrane as the concentrate. It contains natural and synthetic organic matter (COD ca. 30 mg/L) and its composition may vary with raw water quality, membrane pre-treatment and NF membrane cut-off. This study aims to achieve complete elimination of pesticides and the elimination of 60% of the natural organic matter (NOM) retained during nanofi ltration step. The investigation included testing conventional water treatment techniques—adsorption, coagulation, ozonation—and the combination of ozonation and adsorption processes. Eight pesticides detected most commonly in French surface waters were selected as model micropollutants: atrazine, sulcotrione, bentazone, isoproturon, diuron, glyphosate, amitrole and acetochlore. Simultaneous combination of ozonation and powdered activated carbon (PAC) adsorption proved to be an effi cient method for the elimina...

Innovation of conventional water treatment techniques in effluent reclamation

For reclamation of waste water treatment plant (wwtp) effluent, conventional water treatment techniques used in drinking water supply may be suitable. Earlier studies and experiments showed that the most promising cost-effective conventional techniques to polish wwtp effluent are coagulation and rapid multi-media filtration (direct filtration). In the past 4 years these techniques were tested in long term experiments on pilot scale (5-10 m3/h) at several waste water treatment plants in The Netherlands. For successful application of direct filtration for the removal of suspended solids and colloidal material careful consideration is needed with the coagulation conditions. However additional treatment is required to meet the standards for household and process water with respect to ammonium, colour, pathogens and (biodegradable) organic substances.

REVERSE POTENTIAL PHENOMENA IN THE MEMBRANE-ELECTRODE (M-E) PROCESS

Conventional water treatment techniques typically suffer from severe limitations in selective removal and recovery of heavy metals from dilute solutions. For instance, treatment by pH control, chemical reduction, and chemical oxidation result in precipitation of heavy metaJs, which are subsequently landfilled. Ion exchange suffers from lack of selectivity in cation removal from multi-component mixtures, while electrochemical reduction has severe limitations in dilute solutions. In order to address the problem of selective heavy metal removal and recovery, development of the Membrane-Electrode (M-E) process was undertaken. The M-E process is a hybrid of electrochemical reduction and ion-exchange technologies and permits selective ion-exchange from dilute aqueous solutions. High cation selectivities in the M-E process is due to controlled rate of ion-exchange. It has been discovered that cation exchange rates can be controlled by application of an electrical potential difference (pd), and that an inverse relationship exists between pd and the rate of ion-exchange. This behavior is termed as the “Reverse-Potential Phenomena”. Typically, the rate of ion-exchange in conventional ion-exchange processes is dependent upon the cation concentration in solution, and cation loading on the ion-exchange material; this rate cannot be controlled by external means. Thus far, the M-E process has been effectively demonstrated for selective recovery of Pb2+ and Cu2+ ions from dilute aqueous binary and ternary cation solutions [,]. This paper focuses on the effect of Reverse-Potential phenomena on selectivity in the Cu2+ and Ni2+ binary solution mixture.

Removal of Naturally Occurring Mycotoxins from an Aqueous Substrate

Abstract Certain species of fungi, eg. Fusarium, produce mycotoxins, i.e. naturally toxic organic compounds, in response to certain adverse growth conditions. Although the severe effects of ingesting mycotoxin-contaminated grains (eg. corn and wheat) by humans and/or animals are well documented, there are no documented cases of mycotoxin-contaminated drinking waters. However, since natural and man-made mycotoxin production exists, the possibility of mycotoxin contamination of drinking water was deemed to exist. The objective of this investigation was, therefore, to determine which water treatment methods would be successful in the removal of mycotoxins from freshwaters. The experimental test procedures were based on a 50 mg/L stock solution of T-2 mycotoxin in distilled water which was then subjected to various typical water treatment techniques, Samples of the product waters were analyzed qualitatively and quantitatively using both liquid and gas chromatography techniques. In addition, animal bioassay-type testing was employed to evaluate the potential acute and chronic biological effects of the product waters. The results of these tests indicated that the most effective water treatment methods were (i) adsorption on a synthetic resin, (ii) activated carbon adsorption, (iii) distillation, (iv) lime “stabilization” and (v) reverse osmosis. These methods generally resulted in high degrees of mycotoxin removal and product waters which had little or no effect on the test animals. Conventional water treatment techniques, i.e. coagulation, filtration and disinfection, had little or no effect in removing the particular mycotoxin which was tested.

Removal of asbestos fibres from potable water by coagulation and filtration

There is growing concern that asbestos-like fibres in drinking water could be a potential health hazard. Methods are described for removing asbestiform fibres from potable water based on modifications to conventional water treatment techniques. These include simple sand filtration, diatomaceous earth filtration, chemical coagulation or combinations of these depending on the degree of removal required. The most effective method, involving chemical coagulation with iron salts and polyelectrolytes followed by filtration, resulted in better than 99·8% fibre removal from water containing 12 x 10 6 fibres 1 −1.