Assessment of toxicity and antimicrobial performance of polymeric inorganic coagulant and evaluation for eutrophication reduction.

In this study, the efficacy of the promising iron-based polymeric inorganic coagulant (POFC) was assessed for the reduction of eutrophication effect (freshwater toxicity) and the microbial loads from wastewater. Toxicity assessment for POFC was conducted on mice and skin cell lines. The results confirm the lower toxicity level of POFC. The POFC showed excellent antibacterial efficacy against Gram-positive and Gram-negative bacteria. Moreover, it demonstrated a remarkable effectiveness against black fungus such as Aspergillus niger and Rhizopus oryzae. Additionally, POFC showed antiviral effectiveness against the highly pathogenic H5N1 influenza virus as well as Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). POFC-based treatment gives excellent removal percentages for phosphate, and phosphorus at doses below 60 ppm with a low produced sludge volume that leads to 84% decrease in the rate of eutrophication and freshwater toxicity. At a POFC concentration of 60 ppm, remarkable reduction rates for total coliforms, fecal coliforms, and E. coli were achieved. After POFC-based coagulation, the produced sludge retains a lower bacterial density due to the antibacterial activity of POFC. Furthermore, it revealed that the observed removal efficiencies for fungi and yeasts in the produced sludge reached 85% at a POFC dose of 60 ppm. Overall, our research indicates that POFC has potential for application in pre-treatment of wastewater and serves as an antimicrobial agent.

Processing and characterization of antimicrobial bioplastic films based on green microalgae Scenedesmus obliquus extract-loaded polyurethane.

The green microalga Scenedesmus obliquus, isolated from the Egyptian environment, was used for the synthesis of bio-based plastic materials. Polyurethane (PU) was blended with different proportions (0%, 10%, 20%, and 40%) of chloroform extract to form bioplastic films. The bioplastic films were characterized using water vapor transmission rate measurements and scanning electron microscopy (SEM). The WVTR of pure PU was 193.37 g/m2. day, while the values of algae/PU films were 129.74, 122.56, and 99.75 g/m2.day. S. obliquus reported having Palmitic, which possesses antimicrobial activity and acts as an effective antimicrobial agent in the synthesized bioplastic films. Antimicrobial activity of the algal extract and the synthesized bioplastic films were tested against two Gram-positive bacteria; Staphylococcus aureus, Enterococcus faecalis, two Gram-negative bacteria; Escherichia coli, Pseudomonas aeruginosa, and Candida albicans as a model for fungi. The results indicated that S. obliquus extract exhibited a clear antimicrobial activity against all tested microbes. The antimicrobial rate of bioplastic films containing 40% of the extract reached 100% after 2 h of contact with E. coli and E. faecalis. In conclusion, this study offers a promising future for the use of biodegradable antimicrobial bioplastic films as an affordable and environmentally friendly alternative to plastics in many applications.

Effect of different interfacial surface treatments on the shear bond strength of veneering ceramic and zirconia core.

BACKGROUND: Several interfacial surface treatments of zirconia surfaces have been proposed to improve adhesion to ceramic veneering. However, information regarding the durability and effect of such treatments on the bond strength following such treatments is lacking. AIM OF THE STUDY: This study aimed to evaluate the shear bond strength between veneering ceramic and zirconia core after different interfacial surface treatments. MATERIALS AND METHODS: Fifty-two discs (8 mm in diameter and 3 mm in height) were fabricated from zirconia blanks using a microtome cutting machine. Zirconia discs were divided into four groups (n = 13). Group I was subjected to air-borne abrasion using (Al2O3), group II was coated by bioglass, group III was coated with ZirLiner, and group IV was subjected to wash firing (sprinkle technique). A cylinder (4 mm in diameter and 3 mm in height) of veneering ceramic was fired on top of the zirconia core. Shear bond strength (SBS) between zirconia core and veneering ceramic was evaluated by using a universal testing machine. The data was collected and statistically analysed using One-Way ANOVA followed by multiple pairwise comparisons using Bonferroni adjusted significance level. The failure modes were assessed using a stereomicroscope for each group. RESULTS: The highest mean bond strength was recorded in group III (17.98 ± 2.51 MPa), followed by group II (15.10 ± 4.53 MPa), then group I 14.65 ± 2.97 MPa. The lowest mean bond strength was recorded in group IV (13.28 ± 3.55 MPa). CONCLUSIONS: Surface treatments had an effect on the zirconia-veneer shear bond strength. Liner coating revealed the highest shear bond strength values, significantly higher in comparison to wash firing (sprinkle technique) .

Novel electro-oxidation unit for electro-disinfection of E. coli and some waterborne pathogens during wastewater treatment: batch and continuous experiments.

The prime objective of the current investigation is to evaluate a promising alternative method for disinfection wastewater using a novel electro-oxidation unit. The study focused on determining the best-operating conditions from a techno-economic point of view to be applied to continuous flow simulating actual disinfection modules. The treatment unit consisted of a Plexiglas container with a 3 L volume containing nine cylindrical shape electrodes (6 graphite as anode and 3 stainless steel as a cathode) connected to a variable DC power supply. Determination of the best operating parameters was investigated in batch mode on synthetic wastewater by studying the effect of contact time, current density (CD), total dissolved solids concentration (TDS), and bacterial density. Moreover, the continuous mode experiment was considered on real wastewater from an agricultural drain and the secondary wastewater treatment plant effluent before chlorination. The batch mode results revealed that the best applicable operational conditions that achieved the complete removal of E. coli were at a contact time of less than 5 min, TDS of 2000 mg/L, and CD of 4 mA/cm2. Application of these conditions on the continuous mode experiment indicated the complete removal of all bacterial indicators after 5 min in the drainage wastewater and after 3 min in the secondary treated wastewater. Physico-chemical characterization also suggested that no chlorine by-products displaying the hydroxide ion formed due to water electrolysis is the main reason for prohibiting the growth of pathogenic microbes. The electrical consumption was calculated in the continuous mode and found to be 0.5 kWh/m3 with an operational cost of about 0.06 $/m3, including the cost of adding chemicals to increase the TDS. The results proved that this novel electro-oxidation unit is a robust and affordable disinfection method for complete bacterial removal from wastewater and is more environmentally benign than other conventional disinfection methods.

On-treatment improvement of an emerging psychosomatic depressive disorder among salmonella carriers: a multicenter experience from Egypt.

BACKGROUND: As physicians in a referral hospital, we observed the association between history of enteric fever and somatic disorders associated with low mood. At the Al-Hussein University Hospital, Cairo and the National Liver Institute Hospital, Menoufia, we receive patients from all over Egypt, including rural areas where enteric fever is endemic. AIM: Here in, 60 Egyptian patients referred to us for evaluation of different somatic disorders are reported. METHODS: After extensive evaluations, the patients' symptoms were function-related. Also, their typhoid carrier states were documented, and the severity of depression using Hamilton-D (HAM-D) questionnaire was evaluated and recorded. All patients were treated with ceftriaxone, 2 gm, IV, daily for 15 days. The clinical evaluation and Hamilton score were reassessed at the end of the treatment and 6 weeks thereafter. The patients did not receive any anti-depressant nor anti-anxiety treatment during their course. Typhoid carrier was defined by documenting the history of typhoid fever that was diagnosed by culturing the Salmonella species, and not by serology, isolated from stool culture along with febrile condition, plus the absence of fever in the past 3 weeks. The Widal test was not accepted as a criterion for enrollment. RESULTS: Patients showed clinically significant improvement in the somatic complaints, and their HAM-D score immediately post-treatment that was consolidated for 6 weeks post-treatment completion. CONCLUSION: In this study, the typhoid carrier was associated with the psychosomatic depression that improved by antibiotic therapy.

Bioremediation of oil-contaminated water by bacterial consortium immobilized on environment-friendly biocarriers

BACKGROUND: Accidental oil spills in the Nile River represents a public health concern in Egypt. Bioremediation of oil-contaminated water is efficiently competitive and economically effective compared to mechanical and chemical methods. AIM: The current study aimed to: i) assess using environment-friendly materials as carriers for immobilizing oil-degrading bacteria and ii) evaluate applying these biocarriers for removal of oil from water in a batch experiment. MATERIALS AND METHODS: Four bacterial strains Pseudomonas aeruginosa, Cronobacter sakazakii (recently named Enterobacter sakazakii), Klebsiella oxytoca and Bordetella bronchispetica were immobilized on grinded corn qgualh, Egyptian loofah, palm leaf raffia and sponge. Immobilizing bacterial consortium was carried out by incubating bacteria with carriers at 37°C with shaking at 120 rpm for three days. Biofilm formed on biocarriers was checked using scanning electron microscopy. Biocarriers with immobilized bacterial consortium were used for the removal of oil. Experiments were carried out in flasks each containing 100 ml of mineral salt broth fortified with 1 g/l light crude oil. Flasks were incubated at 37°C with shaking at 120 rpm for nine weeks. Total viable bacterial count and oil and grease were determined weekly. RESULTS: Oil and grease measurements showed a significant removal that reached 68.3, 71.5, 77.7 and 81% for grinded corn qgualh, Egyptian loofah, palm leaf raffia and sponge respectively. Flasks inoculated with sponge biocarriers showed rapid oil removal compared with other biocarriers. Gas chromatography-mass spectrometry (GC-MS) showed a percentage removal that reached 87% for compounds C11 to C32 in case of sponge carrier. CONCLUSION: Immobilizing bacteria on biocarriers showed a good biofilm formation. Immobilized bacterial consortium showed rapid and efficient oil removal in bioremediation processes. Sponge showed dense bacterial colonization and consequently biofilm formation compared with other biocarriers.