Removal of COD and SO42− from Oil Refinery Wastewater Using a Photo-Catalytic System—Comparing TiO2 and Zeolite Efficiencies

Rathilal

Naidoo

2020

Sci Rep

Self Cite

The photocatalytic degradation of a local South Africa oil refinery wastewater was conducted under UV radiation using an aqueous catalyst of titanium dioxide (TiO2), Degussa P25 (80% anatase, 20% rutile) in suspension. the experiment was carried out in a batch aerated photocatalytic reactor based on a central composite design (CCD) and analyzed using response surface methodology (RSM). The effects of three operational variables viz. TiO 2 dosage (2-8 g/L), runtime (30-90 minutes), and airflow rate (0.768-1.48 L/min) were examined for the removal of phenol and soap oil and grease (SOG). The data derived from the CCD, and the successive analysis of variance (ANOVA) showed the TiO 2 dosage to be the most influential factor, while the other factors were also significant (P < 0.0001). Also, the ANOVA test revealed the second-order of tio 2 dosage and runtime as the main interaction factors on the removal efficiency. To maximize the pollutant removal, the optimum conditions were found at runtime of 90 minutes, TiO 2 dosage of 8 g/L, and an aeration flow rate of 1.225 L/min. Under the conditions stated, the percentage removal of phenol (300 ± 7) and SOG (4000 ± 23) were 76% and 88% respectively. At 95% confidence level, the predicted models developed results were in reasonable agreement with that of the experimental data, which confirms the adaptability of the models. The first-order kinetic constants were estimated as 0.136 min −1 and 0.083 min −1 for SOG and phenol respectively. Photocatalysis has attracted worldwide interest due to its potential to use solar energy not only to solve environmental problems but also to provide renewable and sustainable energy 1,2. However, the ever-increasing demand for good water quality and oil refinery products have become expensive commodities with major challenges, which requires thoughtful attention 3,4. Oily waste from petroleum refinery has aliphatic and phenolic compounds, are considerably carcinogenic and toxic to the ecosystem and human health, and therefore their removal from wastewater is of global concern 3,5,6. The tox,icity and extreme instability of oily waste make them not degradable easily, this pose a significant threat to the water bodies and soil 5-7. Meanwhile, the processing of crude oil consumes large volumes of water and generates about 0.4-1.6 times the amount of crude oil processed as oil refinery wastewater (ORW) 8-10. The discharge of ORW with adequate or no treatment, due to their inertness, endocrine-disrupting abilities, and carcinogenic behaviour could also affect water bodies and soil profile negatively 9-11. Therefore, there is the need to develop sustainable and eco-effective methods to mitigate the oily pollutants from the ORW, to produce clean water and a sustainable environment 12. In this case, the photocatalysis technology was considered. Unfortunately, the production of polluted wastewater (ORW) is based on the raw crude oil type, plant configuration, and operational procedure, which varies in physicochemical parameters as compared to urban wa...

Section: Resultsmentioning

confidence: 99%

Photocatalytic degradation of oily waste and phenol from a local South Africa oil refinery wastewater using response methodology

Rathilal

Naidoo

2020

Sci Rep

Self Cite

“…The overlapping beams on the interaction graphs ( Figures A1b, A2b, A3b and A4b) show the model's predicted values and the significant effects of the independent levels. The black and red lines ( Figures A1b, A2b, A3b and A4b) illustrate the low and high levels of the factors, respectively, to maximise the response [26,27]. In all cases (>Figures A1b, A2b, A3b and A4b), keeping the coagulant dosage at 100 mg/L constant and other factors set at low levels, the differences observed between them were highly significant.…”

Section: Response Surface Methodologymentioning

confidence: 84%

Evaluating Pre- and Post-Coagulation Configuration of Dissolved Air Flotation Using Response Surface Methodology

Rathilal

2020

Processes

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The effects of coagulation-dissolved air flotation (DAF) process configuration was studied on oil refinery wastewater. The configuration was done in two ways: acid-coagulation-DAF (pre-treatment) and acid-DAF-coagulation (post-treatment). Two different cationic and polymeric organic coagulants were employed in this study to compare their treatability performance with the two aforementioned configurations. All the coagulants applied before the DAF were found to be effective, with over 85% more contaminant removal efficiency than their post-treatment. Alum, being the most cost-effective coagulant, was then employed with response surface methodology (RSM) to obtain the optimum conditions. These include a coagulant dosage of 100 mg/L, air saturator pressure of 375 kPa and air–water ratio of 10% vol/vol corresponding to a desirability of 92% for the removal of oily pollutants from a local South Africa oil refinery’s wastewater. With the response quadratic models that were developed, the optimum conditions were tested experimentally, which were consistent with the models predicted results at a 95% confidence level.

“…Current emerging micropollutants contaminants (RNA of COVID-19, pesticides, antibiotics, endocrine disrupting compounds) in WWTPs discharges impacts on the likelihood to reuse these waters after treatment [68,69]. When aquatic animals inject the micropollutants contaminants, they alter their endocrine system due to the endocrine-disrupting compounds [70,71].…”

Section: Advanced Oxidation Processmentioning

confidence: 99%

“…Additionally, the process offers other diverse approaches of producing hydroxyl radicals making it more versatile and consequently gives a better approach to adhering to strict guidelines during wastewater treatment. AOPs which include Photocatalysis, ultrasonic process, Fenton and photo-Fenton processes ( [68,69,74,75]. A remarkable feature realized during the process was the eco-friendliness of the end-product, giving it a more efficient outlook to mineralize a broad spectrum of organic pollutants, including COVID-19.…”

Section: Advanced Oxidation Processmentioning

confidence: 99%

“…As AOP generates high influential oxidative agents such as hydroxide (OH − ), yet more explicitly, a neutral variant of hydroxyl radical (•OH) [68,69]. In essence, AOP oxidation potential is twice that of chlorine (commonly used disinfectant), therefore employing AOP as a polishing step in WWTPs is useful [10].…”

Section: Application Of Aop On Viral Loads In Wastewatermentioning

confidence: 99%

See 1 more Smart Citation

Fate of COVID-19 Occurrences in Wastewater Systems: Emerging Detection and Treatment Technologies—A Review

Amankwa

Armah

et al. 2020

Water

Self Cite

The coronavirus (COVID-19) pandemic is currently posing a significant threat to the world’s public health and social-economic growth. Despite the rigorous international lockdown and quarantine efforts, the rate of COVID-19 infectious cases remains exceptionally high. Notwithstanding, the end route of COVID-19, together with emerging contaminants’ (antibiotics, pharmaceuticals, nanoplastics, pesticide, etc.) occurrence in wastewater treatment plants (WWTPs), poses a great challenge in wastewater settings. Therefore, this paper seeks to review an inter-disciplinary and technological approach as a roadmap for the water and wastewater settings to help fight COVID-19 and future waves of pandemics. This study explored wastewater–based epidemiology (WBE) potential for detecting SARS-CoV-2 and its metabolites in wastewater settings. Furthermore, the prospects of integrating innovative and robust technologies such as magnetic nanotechnology, advanced oxidation process, biosensors, and membrane bioreactors into the WWTPs to augment the risk of COVID-19’s environmental impacts and improve water quality are discussed. In terms of the diagnostics of COVID-19, potential biosensors such as sample–answer chip-, paper- and nanomaterials-based biosensors are highlighted. In conclusion, sewage treatment systems, together with magnetic biosensor diagnostics and WBE, could be a possible way to keep a surveillance on the outbreak of COVID-19 in communities around the globe, thereby identifying hotspots and curbing the diagnostic costs of testing. Photocatalysis prospects are high to inactivate coronavirus, and therefore a focus on safe nanotechnology and bioengineering should be encouraged.