Leaching of Phthalate Esters from Microplastics into Seawater

The work presented in this thesis helps in improving the available knowledge of the leaching process of PAEs from plastics under different environmental conditions. Particularly, in proper assigning the re-adsorption loss in the measurement of total leachates in water. On the other hand, the latest information regarding the distribution of PAEs and plastic waste and their ecological risk in the surface waters of the Red Sea and Sharm Obhur Bay is reported. An improved method for the analysis of PAEs was developed, including the control of blank contamination, and the experimental conditions such as extraction time and temperature were optimized. This information may be useful in the analysis of PAEs where it can be of great importance to obtain a precise determination of plastic additives in the complex environmen

Biodegradation of Some Polycyclic Aromatic Hydrocarbons by a Bacterial Consortium Isolated from the Red Sea of Jeddah

Polycyclic aromatic hydrocarbons (PAHs) are considered organic pollutants, which are stable, highly toxic, and carcinogenic. Therefore, it was necessary to find an environmentally friendly way to degrade these compounds and remove them from polluted environments. Water samples polluted with petroleum hydrocarbons were collected from the coast of Jeddah on the Red Sea - Saudi Arabia. The results of the current study showed the ability of bacterial consortium that was enriched from the coast of Jeddah, Saudi Arabia to degrade petroleum hydrocarbons wastewater, which proved its ability to degrade PAHs in saline conditions. The bacterial union degraded BENZ compound by more than 95% at the concentration of 100 and 250 mg/L, while the degradation of this compound at the concentration of 1000 mg/L was recorded about 83% while the ANT degradation rate was recorded at more than 90% at different concentrations. In addition, this study revealed the ability of bacterial consortium to treat petroleum hydrocarbons wastewater in bioreactor (CSTR) with 92.7% of COD removed under saline conditions. Hence, this study recommends the investment of bacterial consortium in the treatment of petroleum hydrocarbons wastewater in marine environments and to remove pollutants from them

An Improved Method for Measuring Phthalates in Seawater With Blank Contamination Using GC-MS

Quantification of phthalates or phthalic acid esters (PAEs) might be problematic due to matrix overlap, auto-self absorbance and background scattering noise by the plastic lab materials although plastics have been reported in the release of PAEs. These materials (ambient air, reagents bottles, sampling devices, and various analytical instruments), are ubiquitous in the laboratory environment, thereby making it more difficult to reliably analyze of trace concentration of PAEs. Thus, in the current study, a straight forward and reliable protocol has been established for the analysis of PAEs including control of blank contamination, and the experimental conditions such as extraction time and temperature were optimized. The mass of PAEs in blank tests of selected materials ranged from 3±0.7 to 35±6 ng for liquid-liquid extraction (LLE) and from 5±1.8 to 63±15 ng for solid-phase extraction (SPE). For both extraction methods, higher blank values were measured for dibutyl phthalate (DBP) (35±6 ng, 12±3 ng), and DEHP (63±12 ng, 23±5 ng) in LLE and SPE, respectively. Average recoveries of PAEs in LLE were 90-97% and obtained with successive aliquots of 2 mL, 1 mL, and 1 mL dichloromethane (DCM). For SPE, recoveries up to 86-90% were achieved with successive aliquots of 5, 3, and 2 mL DCM at a sample flow rate of 5 mL min -1 . Under the optimized conditions, the method quantification limits (MQL) for PAEs was 10-20 ng L -1 for LLE and 10-35 ng L -1 for SPE. Moreover, the dissolved concentrations of PAEs from LDPE measured by the LLE method ranged < 1.5 to 5.83 ng cm -2, and those measured by SPE ranged from 1.0to256ngL -1 , in seawater samples of Sharm Obhur. The method has lower MQL values for LLE and SPE than average reported values of 10-100 ng L -1 and 30-100 ng L -1 , respectively

Leaching of Phthalate Esters from Microplastics into Seawater

The current thesis reports a clear understanding of the leaching process of six PAEs from three common consumer plastics, low and high-density polyethylene (LDPE, HDPE) and recycled polyethylene (RP). The effects of salinity, temperature, and ultraviolet irradiation (UVR) on leaching were investigated. Temperature and UVR had a positive effect on the leaching rate while increasing salinity had a negative effect on the leaching rate. The approach used in this study to measure PAEs takes into account the re-adsorption loss of each target compound during the leaching process. Significant re-adsorption of PAEs was observed for all three polymers, which can reduce the amount of actual/total leachate in the dissolved phase by up to 30-80%. This is an important step in understanding the hazards and extent of exposure to additives from plastic pollution. The second major focus of the work is to investigate the relationship between PAEs and PDs in the marine environment. We investigated the abundance of PDs and PAEs in the surface waters of Sharm Obhur Bay and the Red Sea. PAE concentrations in the study area ranged from 0.8 to 1224 ng/L, while the abundance of PDs ranged from (0.0301-0.0374 PDs/m3 ). A positive correlation was observed between the abundance of PDs and the concentration of PAEs, suggesting that a large portion of the dissolved PAE pool may be due to in situ leaching. The calculated ecological risk level (ERL) due to PAEs and PDs for Sharm Obhur and the Red Sea is currently at a low to moderate level. Overall, the work presented in this thesis helps in improving the available knowledge of the leaching process of PAEs from plastics under different environmental conditions. Particularly, in proper assigning the re-adsorption loss in the measurement of total leachates in water. On the other hand, the latest information regarding the distribution of PAEs and plastic waste and their ecological risk in the surface waters of the Red Sea and Sharm Obhur Bay is reported. An improved method for the analysis of PAEs was developed, including the control of blank contamination, and the experimental conditions such as extraction time and temperature were optimized. This information may be useful in the analysis of PAEs where it can be of great importance to obtain a precise determination of plastic additives in the complex environment

A versatile optical assay plate fabricated from e-waste and its application towards rapid determination of Fe³⁺ ions in water

Fabricating an optical assay plate from e-waste and demonstrating its applicability towards one-step assays.</p

Role of a halothermophilic bacterial consortium for the biodegradation of PAHs and the treatment of petroleum wastewater at extreme conditions

Petroleum hydrocarbons are major pollutants in marine environments. The present study describes the potential of a halothermophilic bacterial consortium capable of degrading polycyclic aromatic hydrocarbons (PAHs) in petroleum wastewater under extreme conditions. The consortium was enriched from brine originating from a desalination plant. The consortium efficiently degraded both the low molecular weight (LMW) PAHs-naphthalene (NAP), phenanthrene (PHN), anthracene (AN) and fluorene (FLU) as well as the high molecular weight (HMW) PAHs-pyrene (PY), benzo(e)pyrene (B(e)P) and benzo(k)fluoranthene (B(k)F), respectively. A nearly quantitative release of carbon dioxide (85 ± 1.2%) in conjunction with significant reduction of PAH concentration and an increase in bacterial cell count (from 104 to 109 cfu/mL) pointed at mineralization of PHN. The consortium was able degrade 86± 2.7% and 58± 4.1% of PHN (200 ppm) at 20% and 30% NaCl concentration respectively. Co-metabolism with PHN thereby enhanced the degradation of HMW PAHs. In petroleum refinery wastewater the PAHs were potently degraded by the bacterial consortium with 94 ± 3.8% COD removal in a continuous stirred tank reactor. Ochrobactrum halosaudia strain AJH1, Ochrobactrum halosaudia strain AJH2 and Pseudomonas aeruginosa strain AJH3 were present in the PAH-degrading halothermophilic consortium