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

Abstract

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.

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

“…Therefore, the relationship between three factors (catalyst dosage, reaction time, and aeration flow rate) on the response variables (SOG and Phenol) were then examined using RSM. For graphical representation, three-dimensional response surface plots were used to ease visualization of the interaction effects of the input factors 46,55,56 . The experimental data obtained for the removal of SOG and phenol using the photocatalytic system with TiO 2 nanoparticle is presented in Table 3.…”

“…The model-independent terms (A, B, and C), interaction terms (AB, AC, and BC) and the quadratic terms (A 2 , B 2 , and C 2 ) were found to be significant (P < 0.0001). These were selected based on the P-values being less than 0.05 and adequate precisions being greater than 4 with the regression coefficient closer to 1 55,56 . The negative and positive coefficient terms show that individual or interaction terms in the model can affect the response either decreasing or increasing the degradation efficiency 45 .…”

“…unlike the alkaline medium (>5.5) where it becomes negatively charged 59 . However, most of the organic compounds in ORW (like SOG, phenol, and other phenolic derivatives) are negatively charged 55,56 . Hence acidic medium favors their electrostatic force of attraction towards the TiO 2 charged surface 59,60 .…”

The Usability of Sorbents in Restoring Enzymatic Activity in Soils Polluted with Petroleum-Derived Products

“…Currently, among the methods of the reclamation of soils contaminated by petroleum-derived products, mainly physical, chemical and biological methods are proposed [ 44 ]. Physical remediation requires the implementation of countermeasures, such as vapor extraction, flotation, ultrasound, electrokinetic remediation, thermal desorption and carbon adsorption [ 45 ]. However, most of these methods have their limitations.…”

In Situ Fenton Triggered PDA Coating Copper Mesh with Underwater Superoleophobic Property for Oily Wastewater Pretreatment

“…As an integral part of practical engineering application, pre-treatment is conducted to remove inorganic particles, floating oil, and some emulsified oil, paving the way for post-treatments [5]. Conventional oily wastewater pretreatment process methods such as coagulation-flocculation, skimming, and centrifugation are limited by low separation efficiency, high energy cost, and tedious manual operation [6]. Hence, a new pretreatment approach with strong machine performance for inorganic particle interception, good oil/water separation capability for large flux pretreatment, and low energy input is highly desired.…”