https://cyberleninka.org/article/n/567486.pdf

A review on polycyclic aromatic hydrocarbons: Source, environmental impact, effect on human health and remediation

One of our era's greatest scourges is air pollution, on account not only of its impact on climate change but also its impact on public and individual health due to increasing morbidity and mortality. There are many pollutants that are major factors in disease in humans. Among them, Particulate Matter (PM), particles of variable but very small diameter, penetrate the respiratory system via inhalation, causing respiratory and cardiovascular diseases, reproductive and central nervous system dysfunctions, and cancer. Despite the fact that ozone in the stratosphere plays a protective role against ultraviolet irradiation, it is harmful when in high concentration at ground level, also affecting the respiratory and cardiovascular system. Furthermore, nitrogen oxide, sulfur dioxide, Volatile Organic Compounds (VOCs), dioxins, and polycyclic aromatic hydrocarbons (PAHs) are all considered air pollutants that are harmful to humans. Carbon monoxide can even provoke direct poisoning when breathed in at high levels. Heavy metals such as lead, when absorbed into the human body, can lead to direct poisoning or chronic intoxication, depending on exposure. Diseases occurring from the aforementioned substances include principally respiratory problems such as Chronic Obstructive Pulmonary Disease (COPD), asthma, bronchiolitis, and also lung cancer, cardiovascular events, central nervous system dysfunctions, and cutaneous diseases. Last but not least, climate change resulting from environmental pollution affects the geographical distribution of many infectious diseases, as do natural disasters. The only way to tackle this problem is through public awareness coupled with a multidisciplinary approach by scientific experts; national and international organizations must address the emergence of this threat and propose sustainable solutions.

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Environmental and Health Impacts of Air Pollution: A Review.

Polycyclic aromatic hydrocarbons (PAHs) include a group of organic priority pollutants of critical environmental and public health concern due to their toxic, genotoxic, mutagenic and/or carcinogenic properties and their ubiquitous occurrence as well as recalcitrance. The increased awareness of their various adverse effects on ecosystem and human health has led to a dramatic increase in research aimed towards removing PAHs from the environment. PAHs may undergo adsorption, volatilization, photolysis, and chemical oxidation, although transformation by microorganisms is the major neutralization process of PAH-contaminated sites in an ecologically accepted manner. Microbial degradation of PAHs depends on various environmental conditions, such as nutrients, number and kind of the microorganisms, nature as well as chemical property of the PAH being degraded. A wide variety of bacterial, fungal and algal species have the potential to degrade/transform PAHs, among which bacteria and fungi mediated degradation has been studied most extensively. In last few decades microbial community analysis, biochemical pathway for PAHs degradation, gene organization, enzyme system, genetic regulation for PAH degradation have been explored in great detail. Although, xenobiotic-degrading microorganisms have incredible potential to restore contaminated environments inexpensively yet effectively, but new advancements are required to make such microbes effective and more powerful in removing those compounds, which were once thought to be recalcitrant. Recent analytical chemistry and genetic engineering tools might help to improve the efficiency of degradation of PAHs by microorganisms, and minimize uncertainties of successful bioremediation. However, appropriate implementation of the potential of naturally occurring microorganisms for field bioremediation could be considerably enhanced by optimizing certain factors such as bioavailability, adsorption and mass transfer of PAHs. The main purpose of this review is to provide an overview of current knowledge of bacteria, halophilic archaea, fungi and algae mediated degradation/transformation of PAHs. In addition, factors affecting PAHs degradation in the environment, recent advancement in genetic, genomic, proteomic and metabolomic techniques are also highlighted with an aim to facilitate the development of a new insight into the bioremediation of PAH in the environment.

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Current State of Knowledge in Microbial Degradation of Polycyclic Aromatic Hydrocarbons (PAHs): A Review

Solid waste issue: Sources, composition, disposal, recycling, and valorization

Removal of heavy metal from industrial wastewater using modified activated coconut shell carbon

Removal of pharmaceutical compounds from urine via chemical coagulation by green synthesized ZnO-nanoparticles followed by microfiltration for safe reuse

Different designs of sand filter as a secondary treatment step for the treatment of the primary sedimented effluent were studied. Gravel filter down flow (GFDF), gravel filter up flow (GFUF), sand filter down flow (SFDF), gravel filter followed by sand filter (GFSF), and horizontal flow sand filter (HFSF) were used as a secondary treatment step. During the study period, GFDF, GFUF, and SFDF were operated with an influent flow rate of 173 m3/m2/d, while GFSF and HFSF were operated at flow rate of 86.5 m3/m2/d. The final effluent of GFSF and HFSF were found to be complying with the National Regulatory Standards for the treated effluent reuse in irrigation. The residual concentration of COD, BOD5, and TSS for GFSF was 43, 16, and 7.5 while, the corresponding concentration for HFSF was 40, 17, and 9 mg/l, respectively.

Greywater treatment using different designs of sand filters

Integration of septic tank and constructed wetland systems as simple and low cost techniques is the main objective of this study. The area of the study is located at east of Sharquiya Governorate, Egypt. Three-chamber septic tank of the volume of 56 m3 was constructed followed by 200 m2 subsurface flow constructed wetland. The calculated hydraulic residence time for septic tank and constructed wetland was about 5, 6, and 7 day, respectively. The characteristics of raw wastewater, septic tank, and wetland effluents were studied in terms of physico-chemical and bacteriological parameters. The obtained results revealed that the level of organic load represented by COD and BOD were reduced by 87 and 89%, respectively, while the fecal coliform count was reduced by about 5 log units. The quality of the treated wastewater was found to be within the permissible Egyptian standards for irrigating. No problems with odor or insects exist.

Integration of septic tank and constructed wetland for the treatment of wastewater in Egypt

Separation of wastewater at the source point may enable grey water to be reused for non-potable purposes such as landscape irrigation, toilet flushing and laundry washing. The present study deals with real grey water that was collected from five flats and connected to a pilot plant. The objective of this study was to investigate different hybrid treatment processes for handling the grey water for unrestricted reuse. The viability and efficiency of a sedimentation process at different times followed by an aeration system was examined. The addition of Effective Micro-organism (EM) to the sedimentation process to enhance the efficiency was investigated. The experimental method involves monitoring of specific water quality constituents under varying operating conditions at different sedimentation times, EM doses and aeration rates. The purpose is to reach the unrestricted water reuse. Grey water treatment was examined first in batch experiments to determine the optimum operating conditions including: the settling time, the dose of EM and the aeration time. The obtained optimum conditions were implemented in pilot plant investigation. The pilot plant study was examined at both 3.0 and 4.5 h settling time followed by aeration for 90 min; the removal rates were 70.8, 63.1, 70.6 and 63.5% for the TSS, COD, BOD 5 and oil & grease, respectively. By increasing the settling time to 4.5 h followed by aeration for 120 min, the final treated effluent was still below the requirements of the “unrestricted reuse”. Such treatment was not sufficient to reach the characteristics of unrestricted reuse. To enhance the treatment efficiency of the above system, EM was added at 1.2 mg/L where the characteristics of the final effluent could cope with the permissible level of the 2nd group (secondary treatment) for reuse in irrigation according to the “Egyptian Guideline”. Further improvement was investigated by increasing the EM dose to 1.5 and the settling time to 4.5 h, followed by aeration for 90 min. The removal rates reached 98.1, 91.1, 96.1 and 96.2% for the TSS, COD, BOD 5 and oil & grease, respectively. The Escherichia coli count and the Number of cells or eggs of Nimatoda in the final effluent reached 100 ml/L and Count/L, respectively. This final effluent could cope with the permissible limits of the unrestricted water reuse according to “Egyptian Guideline” regulations.

Greywater treatment via hybrid integrated systems for unrestricted reuse in Egypt

This work investigates the effect of electrocoagulation (EC) using Al, Fe, and Zn electrodes for removing hardness ions and dissolved silica from cooling tower blowdown (CTB) water. The real samples were collected from urea fertilizer factory (Helwan Fertilizer Company), Cairo, Egypt. The effect of operational parameters, such as current density, electrolysis time, inter-electrode distance and stirring rate were studied and evaluated for the maximum efficiency. At the optimum operational conditions, Al-electrode removed the scale forming species from CTB water more efficiently than Zn and Fe electrodes. Al, Fe, and Zn electrodes removed 55.36% and 99.54%, 36.99% and 98.93% as well as 38.63% and 95.62% for the total hardness and silica ions, respectively. In order to rationalize the removal mechanism, the EC generated sludge was characterized by SEM-EDX, XRD, and FTIR. The present investigation inferred that Al-EC generates amorphous nature crystalline and other anode materials (Fe and Zn) forms definite crystalline particles. EDX showed the presence of Ca2+, Mg2+, and silica ions in the sludge which proved the removal of these scale species from CTB water. As a conclusion, this study revealed that EC process using Al-electrode is a promising technology for the removal of scale forming species from CTB water.

Hussein I. Abdel-Shafy

Papers

Removal of pharmaceutical compounds from urine via chemical coagulation by green synthesized ZnO-nanoparticles followed by microfiltration for safe reuse

Greywater treatment using different designs of sand filters

Integration of septic tank and constructed wetland for the treatment of wastewater in Egypt

Greywater treatment via hybrid integrated systems for unrestricted reuse in Egypt

Removal of scale forming species from cooling tower blowdown water by electrocoagulation using different electrodes