Papers by Djamel Ghernaout
Since the 1970s' disinfection by-products (DBPs) detection, the water treatment specialists&#... more Since the 1970s' disinfection by-products (DBPs) detection, the water treatment specialists' main focuses were accorded to the DBPs formation, characterization, regulations and control. Involved stages in disinfection process were at a certain level kept at the side as a black box. This paper is a broad review on chlorination applied in water treatment technology especially in terms of involved mechanisms. Chlorine occasions significant injury to bacterial cells, cell permeability dislocation and nucleic acids and enzymes injury. Hypochlorous acid oxidizes sulfhydryl groups, harms iron-sulfur centers, deactivates nutrient transport, hinders cell respiration, and deteriorates the capacity of cells to keep a sufficient adenylate energy charge to stay viable. All disinfectants are highly efficient killing agents. However, these chemical products are very toxic by their selves. Moreover, they interact with NOM, microorganisms, and algae to produce DBPs which are as well poisonou...
OALib, 2021
The manifestation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in water and wa... more The manifestation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in water and wastewater has newly been revealed. The stools and masks of the patients diagnosed with coronavirus disease (COVID-19) were viewed as the key way of CoV diffusion into aquatic medium. Most CoV kinds that attack human (likely for SARS-CoV-2) are frequently demobilized quickly in water (the endurance of human CoV 229E in water being 7 days at 23˚C). Nevertheless, the endurance time of CoV in water strongly follows temperature, characteristics of water, concentration of suspended solids and organic matter, solution pH, and dose of disinfectant injected. The present disinfection technique of potable water can efficiently demobilize most of the bacterial and viral communities existing in water, particularly SARS-CoV-2 (more vulnerable to killing agent such as free chlorine). Scientists affirmed that SARS-CoV-2 RNA was observed in inflow wastewater and not found in outflow one. Even if the occurrence of SARS-CoV-2 in water influents has been affirmed, a fundamental interrogation is whether it could remain alive or contaminate following the disinfection method of potable water. Until now, only one study asserted that the infectivity of SARS-CoV-2 in water for persons was null founded on the absence of cytopathic effect in infectivity tests. Thus, more researches must be dedicated to the survival of SARS-CoV-2 in water and wastewater below various working circumstances (temperature and water matrix) and whether the diffusion from COVID-19-infected water to human is an emerging anxiety.
For killing viruses such as coronaviruses (CoVs), researchers suggested disinfection chains of ul... more For killing viruses such as coronaviruses (CoVs), researchers suggested disinfection chains of ultraviolet (UV)-C lamps supported by holding stands. Such chains can be folded easily for carrying purpose, and the length of the system could be changed following the need. Such uncomplicated device could be utilized for cheap, reusable and chemical free disinfection of public places; such setup is as well appropriate to neutralize the airborne viruses, even if the application of disinfection should be realized in absence of humans to avert the hazardous influence of UV rays on skin. On the other hand, chemical disinfectants are largely utilized on common touch surfaces in public settings, as a means of controlling the Cov propagation. Nonetheless, the continuous introduction of such dangerous chemicals can exacerbate the growth of biocide-tolerant and antibiotic-resistant bacteria on those surfaces and allow their direct transfers to humans. For these reasons, UV disinfection technology...
OALib, 2020
Coagulation and flocculation processes could reduce particulate algal cells efficiently, but they... more Coagulation and flocculation processes could reduce particulate algal cells efficiently, but they are not so performant in dealing with solubilized algal organic matter in potable water factories. This work reviews the main findings found in recent publications. Many techniques used in the water treatment industry encounter the problem of microalgae lysis, toxin release, and degradation. Indeed, chemical coagulants such as alum and pre-oxidation injecting chlorine can trigger demolition to algal cell integrity leading to the release of intracellular organic matter. As suggestion, chlorination could be decreased to the disinfection (i.e., before sand filtration) averting pre-disinfection and keeping the post-disinfection. Moreover, algae recuperation instead of its removal in drinking water treatment plants remains an encouraging outlook especially if the surface water arrives from dams where algae blooms happen usually. Algae remain a sustainable energy resource with a huge capacity for CO 2 fixation. The micro-algae could be developed in photo-bioreactors or in open ponds. A fresh attracting domain of investigation would be fast and simultaneous algal biodiesel production with drinking water treatment in the biodiesel production/water treatment plant without chemicals use.
International Journal of ADVANCED AND APPLIED SCIENCES, 2018
In the last few decades, many researches on the effects of magnetic field (MF) on water have been... more In the last few decades, many researches on the effects of magnetic field (MF) on water have been reported; however, still many arguments and doubts are present. This review aims to focus on the basic properties implied in magnetic phenomena generation at the atomic and electronic level of matter. Fundamentals of magnetism and origin of magnetic effect will be discussed. Both paramagnetism and diamagnetism are very crucial in the examination of atomic and molecular structure; however, these effects are very weak and have no real practical importance. Large scale magnetic effects resulting in commercially important materials appear in atoms and ions of only a few metallic elements notably Fe, Co, Ni, and some of the rare earths. In alloys or oxides of some materials containing these elements and some neighboring ions such as Mn, there is a crucial improvement of the atomic spin effect. This enhancement comes about from the cooperative interaction of large numbers (10 13-10 14) of these atomic spins producing a region where all atomic spins within it are aligned parallel (positive exchange interaction). These materials are called ferromagnetic. In spite of the achieved performances on MF technologies, there is a huge work to be performed for better understanding and controlling of magnetic water treatment.
OALib, 2020
Electrocoagulation (EC) is a flourishing technique in the field of water treatment implementation... more Electrocoagulation (EC) is a flourishing technique in the field of water treatment implementations. Numerous investigations have been performed to assess the performance of EC to eliminate different pollutants; however, the more basic electrochemical features of the technique are usually ignored. Scientists such as McBeath et al. [1] provided an understanding of the essential link of water flow, electrochemical metal dissolution, and current density distribution (CDD) via computational fluid dynamic (CFD) models, mathematical models, and in situ CDD determination tests. They established, in theory, that current distributed over the electrode was inversely proportional to the water flow rate. By means of the CFD models and current distribution determining technique, they noted that current density was distributed unequally and pursued the tendency anticipated via theory. Eliminating natural organic matter was decreased as much as 79% when the inter-electrode distance was diminished from 10 to 1 mm. As a perspective, more efforts are required to better understand the CDD at the anodes surface and electric charges transfer from electrodes to the bulk of the solution. Mechanisms related to interactions of anodic metallic cations and various pollutants should be more investigated.
International Journal of ADVANCED AND APPLIED SCIENCES, 2018
Nowadays, reverse osmosis (RO) is the most largely utilized desalination process at the World lev... more Nowadays, reverse osmosis (RO) is the most largely utilized desalination process at the World level. During the three last decades, amazing progress has been realized in the manufacturing of RO membranes using different materials. However, what is astonishing here is the fact that a new research field was open in a relatively short time with hundreds of scientific publications and patents which are made on membrane post-synthesis modifications in order to improve the structural properties and desalination performance opening a large debate about the membrane fabrication techniques and membranes capacities to deal with various water pollutants. This review aims to discuss this extra technological field dedicated to membranes modifications following their fabrication. As conclusions, membrane fabrication methods are a well-established and developed technology which however needs more technical improvements to overcome the needs of a post-synthesis industry and satisfy quantitatively and qualitatively the water guidelines. On the other hand, the large chemical products use in both membranes synthesis and post-synthesis should be avoided or at least reduced, since monomers, alcohols, acids and bases risk to be realized into drinking water. That is said because RO process has been presented hopefully as a promising powerful and green technology instead of chlorination and coagulation/flocculation which are proven highly polluting with their toxic metal salts injection and poisonous disinfection by-products formation.
American Journal of Environmental Protection, 2017
One of the most important grants of God Almighty to mankind is iron. The reality that there is a ... more One of the most important grants of God Almighty to mankind is iron. The reality that there is a Chapter named "Al-Hadid" (Iron) in the Holy Koran can be considered as a sign of its significance. The reality that there is not a Chapter called "adh-Dhahab" (Gold) might be a sign that iron is more crucial than gold since life would go on if gold did not exist but it would not be easy to mention human civilization without iron. Iron is (1) the essential of all of the arts, (2) the source of human development and progress, and (3) in the center of the strength of man. Due to its functions mentioned above and similar ones, the following is stated in the Koran: "…and We sent down Iron, in which is (material for) mighty war, as well as many benefits for mankind...". The fact that this Verse particularly introduces iron is completely astonishing, taking into account that these findings were realized at the termination of the 20th century.
OALib, 2020
Coagulation remains a technique by which finely dispersed solids are efficiently eliminated. It h... more Coagulation remains a technique by which finely dispersed solids are efficiently eliminated. It has been largely expanded and remains the most unavoidable method for treating water. This review focuses on colloid stability, coagulation mechanisms, and coagulant types. It presents electrocoagulation as an option of conventional coagulation and discusses challenges in coagulation technology especially health hazards in used chemicals toxicity. As promising solutions, new developments in terms of using coagulants are presented. Micropollutants are inorganic and organic substances that could disturb negatively nature even at very low levels. Microplastics are also observed. Coagulation could retain different micropollutants and microplastics at varying efficiencies even if there is a need to determine running circumstances that could increase their reduction. As a perspective, coagulation may be combined with additional processes, such as ultrafiltration. Further, traditional water treatment should be deeply revised.
International Journal of ADVANCED AND APPLIED SCIENCES, 2018
The generation, monitoring, and health impacts of disinfection by-products (DBPs) in potable wate... more The generation, monitoring, and health impacts of disinfection by-products (DBPs) in potable water are problems of worldwide worry. Several nations, besides the World Health Organization, possess regulations and/or guidelines on bearable levels of DBPs in water. Since drinking water is frequently remediated using a chemical killing agent, DBPs are pollutants to which several humans are unprotected. On account of the health impacts linked to subjection to chlorinated water and/or some DBPs, the water manufacturing has performed great endeavors to equilibrate killing pathogens and DBP monitoring. Large survey has been realized on rising DBPs of health and regulatory worry. In spite of the fact that the attention on DBPs was previously on chlorine-and bromine-containing carbonaceous DBPs, appearing DBPs comprise iodine-containing species, also halogenated and non-halogenated nitrogenous DBPs. In addition, latest toxicity experimentation has proposed that certain of the more recent PBPs are of more elevated toxicity than some of the regulated chemical products. Therefore, survey has been realized to better comprehend how to costeffectively monitor a large interval of regulated and appearing DBPs. This comprises the usage of advanced remediation and killing pathogens methodologies. This paper shows certain of the newest research works at comprehending these significant DBP-related problems. Disinfection is killing microorganisms present in water; but, it is as well killing human beings drinking water by poisonous DBPs. Using chemicals for water treatment is finally a lost cause.
OALib, 2020
At the worldwide level, with numerous full-scale plants dealing with urban and industrial wastewa... more At the worldwide level, with numerous full-scale plants dealing with urban and industrial wastewater, the membrane bioreactor (MBR) process is viewed as a fully developed technique. Nevertheless, membrane fouling constitutes a critical barrier in the larger diffusion of MBR application. This work aims to discuss the new research and development progresses in the MBR technology in terms of fouling mitigation. New arrangements are examined to enhance the comprehension of the latest achievements in MBRs. Employed for biological fouling control, the quorum quenching technique is briefly introduced. As clean methods used for coping with membrane fouling, the ultrasonic technique and the surface grafting methods are also suggested. Several ameliorations focused on the module arrangement, aeration procedures, control setups, surface amendments, low-energy membrane cleaning techniques, or new fouling mitigation procedures, for instance, mechanical cleaning with granular medium, membrane vibration, or electric field. Between such ameliorations, hybrid setups, merging MBR with different techniques, employing prospects of the diverse methods to get the better of regular limitations of the MBRs are the most convenient. Nonetheless, implementing such novel fouling alleviation procedures for large scale MBRs needs more study. Sustainable control of membrane fouling necessitates utilizing more than one single strategy. Even with unceasing enhancements and expansions, fouling control features remain to be fully met.
OALib, 2020
Taking into account its merits in terms of high efficiency and low energy consumption, electroche... more Taking into account its merits in terms of high efficiency and low energy consumption, electrochemical (EC) technology especially bioelectrochemical system (BES) has been applied largely in reducing different antibiotics from wastewater. BES averts the spread of antibiotic resistance genes (ARGs) via forming less quantity of sludge compared with wastewater treatment plants. Nevertheless, transmembrane permeability and membrane potential could be influenced by the electrical stimulation, conducting to augmentations in the antibiotic-resistant bacteria (ARB) and ARGs in BES. This work discusses the utilization of EC technology especially BES for antibiotic reduction and the fate of ARB and ARGs in such systems. BES can effectively remove antibiotics. Nevertheless, low electric current promotes vertical and horizontal ARGs transfer during the treatment of antibiotics in BES. ARB and ARGs could be inhibited by a higher electric current. Questions regarding the potential role of BES in antibiotic removal and the consequent fate of ARGs and ARB in wastewater are presented. Further research is needed to elucidate the primary ARG transfer mechanism and to fully understand the advantages of BESs.
OALib, 2020
In spite of the considerable development registered in microbiology, humankind remains incapable ... more In spite of the considerable development registered in microbiology, humankind remains incapable to dominate scientifically and technologically the large microbial world. This is well established and illustrated, unfortunately, in the present Coronavirus disease (COVID-19) pandemic. This work aims to contribute to highlighting the world of pathogenic microorganisms, especially viruses, and their removal from potable water. Identical to the manner by which chemical contaminants are handled in the environment, the particular properties that control transport and demobilization of enveloped viruses in solutions, on surfaces, and in the air must be understood. Besides, the fashion by which ecological parameters form likely virus transmission and mutation mechanisms should be comprehended. Since water treatment constitutes a secure barrier against drinking water infection, the main stages in the water treatment plant dealing with pathogens removal such as disinfection have to be enhanced with more efficient techniques such as advanced oxidations processes. In the field of eliminating pathogens, some research trends are suggested especially those founded on thermal destruction and solar irradiation due to their high performance and low costs.
OALib, 2020
Electrochemical technology for the killing of pathogens has been largely investigated. Lately, Ni... more Electrochemical technology for the killing of pathogens has been largely investigated. Lately, Ni et al. [1] published excellent research on the disinfection efficiency of a carbon fiber-based flow-through electrode system (FES) versus Gram-negative bacteria (Escherichia coli and fecal coliform) and Gram-positive bacteria (Enterococcus faecalis and Bacillus subtilis
International Journal of ADVANCED AND APPLIED SCIENCES, 2018
Water and wastewater systems are important energy consumers with an evaluated 3%-4% of total U.S.... more Water and wastewater systems are important energy consumers with an evaluated 3%-4% of total U.S. electricity consumption employed for the movement and treatment of water and wastewater. Water-energy problems are of increasing significance in the case of water shortages, more elevated energy and material costs, and a varying climate. In this economic context, it is vital for utilities to manage performances, both in water and energy utilization. Carrying out energy audits (EAs) at water and wastewater treatment facilities is one method community energy managers may recognize favorable occasions to save water, energy and money. In this review, the significance of energy utilization in wastewater facilities is shown by a case study of a process EA performed for Crested Butte, Colorado's wastewater treatment plant. The EA detected favorable occasions for crucial energy savings (ESs) by examining power intensive unit processes like influent pumping, aeration, ultraviolet disinfection, and solids handling. This case study shows best practices that may be easily applied by facility managers in their search for energy and financial savings in water and wastewater treatment. This article aims to ameliorate community energy managers' comprehension of the action that the water and wastewater sector performs in a community's total energy consumption. The energy efficiency roadmaps defined give information on ESs favorable occasions, which may be employed as a fundamental concept for treating energy management objectives with water and wastewater treatment facility managers.
OALib, 2020
The most frequently utilized technique for demobilizing pathogens remains disinfection. This is a... more The most frequently utilized technique for demobilizing pathogens remains disinfection. This is a fundamental stage in drinking water treatment as it removes the hazards related to water-borne diseases like typhoid and cholera. Therefore, disinfecting water employing chemical oxidants such as chlorine has been one of the main public health progresses through the previous century. During the time that this preserves the residual concentrations of disinfectant for the control of microbes, it may greatly elevate the generation of disinfection by-products (DBPs). Lately, Chaukura et al. [1] published an excellent review of the presence of organic matter (OM) in water sources and assessed its impact on the generation of DBPs. Especially, they discussed the production of DBPs, examined the contribution of OM on DBPs generation, and estimated and recommended techniques for eliminating DBPs. This work focuses on the main findings obtained by Chaukura et al. [1] and explores the authors' experience in dealing with disinfection processes and their DBPs generation issues as well as the techniques to remove them from water. Enhanced coagulation and membrane processes are efficacious in eliminating OM. An efficacious and economically usable procedure to dominate the production of DBPs in water treatment plants is to eliminate the precursors before they interact with chemical disinfectants, which should be avoided or at least reduced.
World Journal of Applied Chemistry, 2018
There is no doubt that the chemical water treatment has resolved the problem of drinking water su... more There is no doubt that the chemical water treatment has resolved the problem of drinking water supply for several decades to humankind especially in terms of pathogen microorganisms and turbidity removal. However, due to chemicals used through this treatment and increasing quantities of pollutants discharged into nature, numerous health problems have been largely more and more proved and reported. This review discusses the toxicity of chlorine, alum, and polyelectrolyte which are widely employed through the world. The main addressed question here is: When the true and radical water treatment technology will be really and definitely applied? There is no water treatment technique but only distillation process which is successfully applied at the largest scale in nature by God. At least, physical processes such as membrane processes should be more and more applied through water treatment plants for reducing chemicals use. Most of chlorination disadvantages may be avoided through a better understanding of the mutual actions conducting to the generation of chlorine by-products and the use of more sophisticated procedures to assess toxicity capacity of such chemicals. Finally, this study arrives at its time since the Environmental Engineers and the Green Chemistry specialists have largely opened the discussion about polluting industry and preserving nature. Returning Man to its initial and noble Mission on Earth is reflected through this research to preserve both humankind and nature.
World Journal of Applied Chemistry, 2018
This work aims to study coagulation process for hard Ghrib Dam (GD) water treatment. Conventional... more This work aims to study coagulation process for hard Ghrib Dam (GD) water treatment. Conventional coagulation (CC), enhanced coagulation (EC) and alkaline coagulation (AC) experiments were realized on jar tests. This study demonstrated the effectiveness of GD water treatment by the EC process compared to CC. Indeed, by CC, it has been demonstrated that each of the two coagulants studied (alum and FeCl 3) is effective for remarkable reductions in OM of 36% and 47.4%, respectively. However, EC, by slightly acidifying water, gave better removal efficiencies of the studied parameters. Indeed, the best abatement of OM is about 78% when water is treated with ferric chloride at pH 5.5, lowered with nitric acid. The observed disadvantage here is the residual nitrate, which existed in the raw water at only low level. On the other hand, at the same pH, the reduction of the OM is 64% when alum is used as coagulant. In addition, the data collected have led to the conclusion that the physicochemical quality of the GD water has a high salinity and lowering its pH (EC) does not affect it at all. On the other hand, its pH elevation (AC) considerably reduces its total hardness which is 41% with NaOH. Such a performance advantageously positions this total hardness reduction technology among the possible solutions to the problems associated with total hardness.
Journal of Environmental Science and Allied Research, 2019
Electrocoagulation (EC) process is a highly performant technique for treating water particularly ... more Electrocoagulation (EC) process is a highly performant technique for treating water particularly in terms of killing pathogens, especially viruses. This paper discusses briefly some recent advances in removing viruses from water. Routes of bacteriophage reduction due to EC were discussed throughout the literature. Physical elimination was mainly attributed to embodiment in flocs; however, demobilization was firstly linked to ferrous iron oxidation. Removing bacteriophage for any method working on iron has to be seriously viewed because of more important vulnerability of bacteriophages to demobilizing through Fe 2+ oxidizing. Through juxtaposing the traditional treatment via FeCl 3(s) as coagulant and Cl 2(g) as disinfection agent, the EC-electrooxidation (EO) approach was observed less performant in typical surface waters but more performant in typical groundwaters. In many usages, consecutive EC-EO was useful, still real aspects such as free radicals remaining in water risk to overpass the combined process inherent advantages. More research concerning both virus removal and pathogenic bacteria remains to be performed in the perspective of a large industrial usage of EC process.
International Journal of Sustainable Development Research, 2017
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Papers by Djamel Ghernaout