Oily Wastewater Research Articles

High-efficiency treatment of oily wastewater by photocatalytic in-situ Fenton oxidation under visible light

Oily wastewater poses a significant threat to environmental safety, and complex water environments have caused numerous disturbances in oil pollution treatment. Therefore, constructing composite systems is expected to improve oil pollution treatment efficiency. This study developed an efficient photocatalytic in-situ Fenton oxidation system, HTCC@ZnFe2O4/Ag3PO4 (HZFA), loaded onto polypropylene spheres (PP) for treating oily wastewater (diesel oil) in complex environments. The built-in electric field of HZFA promotes photogenerated carrier separation, enhancing photocatalytic effect. At a diesel concentration of 3.2 g/L, performance of HZFA degraded diesel in deionized water and artificial seawater (ASW) were 60.80 % and 52.62 %, respectively, much higher than a pure photocatalytic system (13.84 %). The dual system compensated for single system defects like instability and narrow application range, achieving 8 effective cycles in ASW. Experimental and computational results showed that high oxidation and reduction potentials in the dual system promoted hydrocarbon oxidative degradation and H2O2 production/activation. The amount of OH, O2−, and h+ produced in different environments is fundamental for the stabilization of catalytic degradation by HZFA. GC–MS and DFT analysis revealed potential oxidative chain-breaking processes for diesel components like alkanes, aromatics, alcohols, acids, aldehydes, and esters. This study offers a new method for green and efficient oily wastewater treatment, overcoming inherent defects of traditional Fenton, with broad application prospects.

Kinetic Insights into Solar-Assisted Fabrication and Photocatalytic Performance of CoWO4/NCW Heterostructure

This work studies the kinetic model for the solar-driven fabrication of CoWO4/NCW heterostructure photocatalysts and investigates their enhanced photocatalytic degradation activity. The synthesis of CoWO4/NCW, its characterization, and the kinetic aspects of photocatalytic degradation under solar light. New nanocomposite prepared from Nano cellulose (NCW) by hydrolysis cotton waste (CW) by nitric acid and cobalt tungstate (CoWO4) prepared from sodium tungstate and cobalt chloride by wet chemical method and characterized through XRD, FTIR, EDX, and FE-SEM analyses. The composite's performance in organic oxidation from refinery wastewater (RWW) was evaluated under solar light. The high removal ratio was 97.4% for organic pollutants (OP) in refinery wastewater. The results indicate that the heterostructure exhibits improved photocatalytic performance compared to individual components, which kinetics model was the best to represent the photocatalytic degradation of organic pollutants from oily wastewater over the heterostructure CoWO4/NCW catalyst. Add future applications of this finding in the relevant industries. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Simple and Scalable Approach for Fabrication of a Durable Conjugated Polymer-Decorated Multichannel Tubular Ceramic Membrane with Superoleophobic (Underwater) and Superhydrophilic Surface for Treatment of Oily Wastewater

Simple and Scalable Approach for Fabrication of a Durable Conjugated Polymer-Decorated Multichannel Tubular Ceramic Membrane with Superoleophobic (Underwater) and Superhydrophilic Surface for Treatment of Oily Wastewater

A novel multifunctional photocatalytic membrane based on β-FeOOH for oily wastewater purification

In order to deal with the environmental pollution caused by complex oily wastewater, it is necessary to develop filtration membrane materials. However, significant challenges such as poor effect of emulsion separation, limited functionality, and susceptibility to membrane fouling require urgent resolution. Here, we successfully prepared a β-hydroxyl iron oxide/polydopamine-polyethylenimine/polyacrylonitrile (β-FeOOH/PDA-PEI/PAN) nanofiber membrane for treatment of complex wastewater by growing PDA-PEI on a blow-spinning PAN nanofiber membrane and decorating the membrane with β-FeOOH. The porous structure and the large number of hydrophilic groups greatly increase the hydrophilicity of the membrane and give the membrane high permeation fluxes (11531.26 L m−2 h−1) for surfactant-free kerosene-in-water emulsion. The loaded β-FeOOH nanorods increase the roughness of the membrane surface, which enhances the underwater superoleophobic ability of the membrane, and promotes the demulsification of the emulsion and makes it have high separation efficiency of 99.48 % for surfactant-stabilized kerosene-in-water emulsion. In addition, the β-FeOOH/PDA-PEI/PAN also exhibited high organic dye removal efficiency (99.38 %) due to the presence of β-FeOOH. The synergistic effect of low oil adhesion and photocatalysis enhances the antifouling and self-cleaning performances of the material. Significantly, the multifunctional membrane also shows exceptional oil/water separation ability and good stability. The presented synergistic strategy of β-FeOOH/PDA-PEI/PAN membrane materials represents a prospective candidate for the treatment of complex wastewater.

Optimization, Purification and Characterization of Lipase from Streptomyces sp. A3301, with Application of Crude Lipase for Cooking Oily Wastewater Treatment

Streptomyces sp. A3301, which produces lipase isolated by Panyachanakul et al. [1]. This optimization was done for the subsequent purification and characterization of the biological lipase produced by the isolate. The results showed that the strain produced lipase with a maximum activity of 321 U/mL using the optimal medium and conditions (1.5 % (w/v) xylose and 2 % (w/v) yeast extract, pH 7.0 at 30 °C, 150 rpm for 3 days). The specific activity of the purified lipase was 27,000 U/mg, which was 544 times the pre-purification level, based on hydrophobic chromatography. After ion-exchange chromatography, the specific activity was 5,600 U/mg, which was 113 times the pre-purification level, with a single-peak purification profile. The purified lipase had a single band based on SDS-PAGE analysis and the molecular mass was 45 kDa. The optimum temperature and thermo-stability of A3301 lipase were 60 and 30 - 55 °C, respectively. The optimum pH of the purified enzyme was pH 9.0, and the enzyme was stable in the pH range of 8.0 - 9.0. The purified lipase was stable in acetone, chloroform and toluene, with a high relative activity of 63 - 76 %. The immobilized strain was then applied to oily-wastewater treatment. The strain can remove oil and grease in synthetic wastewater containing oil at 1 - 3 % (v/v), with removal rates of 100, 99.82 and 99.68 %, respectively, after incubation for 6 days. It was then applied to oily-wastewater treatment from a restaurant, achieving the highest degradation rates of 98.53 % after treatment for 6 days. In addition, it also affected the Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) values decreasing. HIGHLIGHTS Optimization of lipase production by Streptomyces A3301. Purification and characterization of the lipase produced by the Streptomyces A3301. Application of the immobilized Streptomyces A3301 strain in the treatment of oily cooking wastewater. The immobilized Streptomyces A3301 strain has the capability to remove oil and grease in both synthetic mediums and restaurant wastewater. GRAPHICAL ABSTRACT

Use of the droplet convergence effect of under-medium superlyophilic membranes in designing a system for on-demand separations of oil-in-water and water-in-oil emulsions

Separation using superwetting membranes that have discrepant interactions with water and oil, primarily those that display extreme liquid repellence, is a facile approach for oily wastewater treatment and purification of water-containing oil. However, these kinds of membranes suffer from size-sieving limitation. Owing to greater affinity toward dispersed droplets over liquid media, under-medium superlyophilic membranes have greater flexibility in the design of superwetting interfaces for oil–water separation. Herein, two membranes with completely opposite superwettabilities both in air and under oil/water media were utilized to create an integrated system for effective, on-demand separation of oil-in-water and water-in-oil emulsions. At superwetting interfaces, the under-medium superlyophilic membrane facilitates convergence of emulsion droplets while the other membrane intercepts converged droplets. As a result, the integrated membranes exhibit high purification capabilities of water and oil in surfactant-stabilized emulsions (e.g., > 99.97 % oil purification under gravity). The viscosity-dependent fluxes are > 550 L m−2h−1 when the viscosities of the liquid media are ≤ 1 mPa s. In contrast, an integrated system in which conventional in-air superhydrophilic membranes are utilized in place of the under-medium superlyophilic membranes does not efficiently separate the emulsions. The unique affinity profiles will endow under-medium superlyophilic membranes with a high potential for liquid–liquid separation.

Innovative strategy for the treatment of oily wastewater by in-situ synthesis of nitrogen-doped biochar supported FeS for activation of peroxymonosulfate

ABSTRACT Disposing of oily wastewater poses a significant challenge in treating oilfield-produced wastewater treatment. This study developed a FeSNC-9/PMS system for the effective degradation of total petroleum hydrocarbons (TPHs) in oily wastewater, while increasing the value of excess sludge, thus achieving the dual purpose of waste treatment. This work involved the in-situ preparation of a porous nitrogen-doped biochar-supported iron sulphide catalyst material using surplus sludge from SBR. Compared to undoped FeS (NC-9), FeSNC-9 exhibited excellent pore structure and abundant functional groups. Fe-Nx served as an effective connecting site between FeS species and the graphite network of biochar. The FeSNC-9/PMS system significantly degraded 74.21% of TPHs within 300 min. The FeSNC-9/PMS system demonstrated remarkable TPHs degradation efficiency across a wide temperature range and under both weak acidity and near-neutral conditions The dominant reactive oxygen species were identified as SO4 •− and •OH, with O2 •− and 1O2 also confirmed as active species. Gas chromatography semi-quantitative analysis showed that the long-chain alkanes of C20-C30 in total petroleum hydrocarbons were significantly degraded into short-chain alkanes or completely mineralized. This work provides new insights for the low-cost and high-efficiency treatment of TPHs in oilfield-produced water, and delves into the activation mechanism of PMS and the degradation pathways of TPHs.

Retraction Note: Microwave-ultrasonic assisted extraction of lignin to synthesize new nano micellar organometallic surfactants for refining oily wastewater

Retraction Note: Microwave-ultrasonic assisted extraction of lignin to synthesize new nano micellar organometallic surfactants for refining oily wastewater

Exploring the Possibilities of Using Recovered Collagen for Contaminants Removal—A Sustainable Approach for Wastewater Treatment

Collagen is a non-toxic polymer that is generated as a residual product by several industries (e.g., leather manufacturing, meat and fish processing). It has been reported to be resistant to bacteria and have excellent retention capacity. However, the recovered collagen does not meet the requirements to be used for pharmaceutical and medical purposes. Due to the scarcity of water resources now affecting all continents, water pollution is a major concern. Another major field that could integrate the collagen generated as a by-product is wastewater treatment. Applications of collagen-based materials in wastewater treatment have been discussed in detail, and comparisons with already frequently used materials have been made. Over the last years, collagen-based materials have been tested for removal of both organic (e.g., pharmaceutical substances, dyes) and inorganic compounds (e.g., heavy metals, noble metals, uranium). They have also been tested for the manufacture of oil-water separation materials; therefore, they could be used for the separation of emulsified oily wastewater. Because they have been analysed for a wide range of substances, collagen-based materials could be good candidates for removing contaminants from wastewater streams that have seasonal variations in composition and concentration. The use of recovered collagen in wastewater treatment makes the method eco-friendly and cost efficient. This paper also discusses some of the challenges related to wastewater treatment: material stability, reuse and disposal. The results showed that collagen-based materials are renewable and reusable without significant loss of initial properties. In the sorption processes, the incorporation of experiments with real wastewater has demonstrated that there is a significant competition among the substances present in the sample.

Valorization of Different Clays Used in the Treatment of Oily Wastewater in the Development of Construction Products

AbstractThe aim of this research is to study the feasibility of using clays used in the decontamination of wastewater containing olive oil wastewater (OOW), new lubricating oil (NOW) or motor oil (MOW) in the manufacture of ceramic bricks. Three types of clays were used for filtration, kaolinite type clay (KT), smectite type clay (CT) both from Tunisia and illitic chloritic clay (CS) from Jaén (Spain). These clays containing different types of oils, as well as the control clays, were used in the manufacture of bricks fired at 900 °C. These bricks were characterized by physical, mechanical and thermal tests. The sintered microstructure’s evolution was followed by tracked through scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The results indicate that the specific type of clay used influences the technological characteristics of the bricks. The use of CT clay gives rise to increase bulk density, greater compressive strength, and reduced apparent porosity and water absorption. The use of clays used in the decontamination of water containing oils produced a decrease in bulk density, compressive strength and thermal conductivity and leads to an increase in apparent porosity and water absorption in the order OOW > NOW > MOW according to the total organic carbon content (TOC). Therefore, the use of clays used in the filtration of water that contain different oils can represent a promising way of valorizing this waste, which can alleviate the environmental impact and represents economic savings for the industry of construction materials with properties of thermal insulation, getting closer to a circular economy.

Hydrophilic PVDF emulsion separation membranes prepared using TA/APTES as a non-solvent: Effect of lithium chloride hydrate additive content

Currently, surfactant-containing oil–water emulsions are the more difficult part of oily wastewater to treat because of their small droplet size and stable oil–water interface. Membrane separation technology is commonly used for emulsion separation due to its surface wettability and adjustable pore size. Here, tannic acid (TA) and 3-aminopropyltriethoxysilane prepolymerization solutions are used as the exchange solvents, allowing growth on the surface and inside of polyvinylidene difluoride (PVDF). Among them, the content of lithium chloride (LCM) hydrate modulates the range and amount of growth. In the pressure range of 0.1–0.7 bar, the modified hydrophilic PVDF-TA/LCM-2 membranes exhibit high pure water permeation fluxes and emulsion separation efficiencies that can be adapted to different separation conditions. At 0.2 bar, the PVDF-TA/LCM-2 achieves pure water permeate flux and emulsion separation fluxes of 1860 and 648 L m-2 h−1 bar−1, and an emulsion separation efficiency of 99.5 %. In addition, for different kinds of oil-in-water emulsions, the high separation fluxes and high separation efficiencies indicate that PVDF-TA/LCM-2has good emulsion separation performance.

In-Situ construction of Bulge-like microstructures in sugarcane-based superhydrophobic membranes for efficient separation of water-in-oil emulsions

The separation of oil/water pollution is of great importance to environmental protection. However, the development of superwetting materials for efficient separation of surfactant-stabilized oil/water emulsions still faces challenges. As agricultural waste, sugarcane straw contains many hydrophilic groups and multilayered pore structures, making it suitable for purifying oil/water emulsions by simple chemical modification treatments. Herein, sugarcane-based superhydrophobic membranes (SSMs) were prepared by a facile vacuum impregnation method in hexadecyltrimethoxysilane (HDTMS) solution. The unique bulge-like microstructures were constructed in the intrinsic pores of sugarcane, which significantly increased the roughness and resulted in superhydrophobicity with the water contact angle of 153.5°. More importantly, the bulge-like structure is easy to break the emulsion and thus SSMs offer excellent separation efficiency (> 99 %), suitable fluxes (368 L•m−2•h−1) and strong cycling stability for surfactant-stabilized water-in-oil emulsions. In addition, SSMs can separate oil/water mixtures and directly adsorb oil from water with adsorption rates exceeding 99 %. SSMs have good durability and anti-mold adherence properties, and they do not lose their unique wetting properties even in harsh environments. More importantly, SSMs can be degraded in soil at the end of their life cycle, avoiding secondary pollution for the environment. This simple, in-situ impregnation technique offers a novel way to create green, inexpensive and stable biomass membranes for effective water-in-oil emulsion separation, showing great promise for use in oily wastewater treatment.

Bifunctional TiO2-Coated SSM for Efficient Emulsion Separation and Photocatalytic Degradation of Soluble Organic Pollutants.

The oily wastewater containing complex organic pollutants poses a great threat to the environment and human beings. At present, the membrane used to treat oily wastewater has some problems, such as complicated preparation and serious membrane pollution. Superhydrophilic/underwater superoleophobic membranes overcome the problems of the surface of the membrane being easily polluted or even blocked by oil, so they have been widely studied by many researchers. In this work, we used an electrochemical deposition method to uniformly load titanium dioxide (TiO2) nanoparticles onto pretreated stainless-steel mesh for efficient oil-in-water (O/W) emulsion separation (TiO2@SSM). The membrane of TiO2@SSM exhibited superior superhydrophilicity and underwater superoleophobicity, ensuring high O/W separation efficiency, reaching 99.8%, and fast water flux of up to 208.0 L·m-2·h-1 for various O/W emulsions. Meanwhile, the membrane possessed a desirable photocatalytic degradation property under visible light irradiation and a degradation efficiency of 98.1% for RhB pollutant. Specially, the as-prepared membrane had long-lasting robustness, sustainability, and recyclability through the cyclic experiments of emulsion separation and photocatalytic degradation. Our results provide a simple and universally applicable route to construct a multifunctional membrane for simultaneously achieving water purification in complex oily wastewater.

Biomimetic super-wetting membranes via in-situ growth and synchronous integration of ZIF nanoleaves (ZIF-Ls) for emulsified oily wastewater purification and catalytic Knoevenagel condensation

To address the increasingly severe oil spill accidents and water contamination, the development of super-wetting membranes with high oil/water separation efficiency is in great demand but remains challenging. The critical challenge lies in the rational design and fabrication of robust rough surface with hierarchical micro/nano-structure. In this study, biomimetic super-wetting polyacrylonitrile composite membrane was developed through in-situ synthesis and synchronous integration of zeolitic imidazolate framework nanoleaves (ZIF-Ls). Thorough investigation was conducted to assess the effect of the ZIF-Ls growth time on membrane morphology and surface wetting property. Incorporating the nanoleaf-like ZIF-Ls onto the surface of the membrane provided the surface with micro/nano rough structure and superamphiphilic/superlyophobic features. The prepared membrane showed great separation capability toward various O/W and W/O emulsions, and could be easily regenerated by employing a simple rinsing and drying procedure with high separation efficiency sustained even after multiple separation cycles. Moreover, the membrane with ZIF-Ls demonstrated outstanding catalytic performance in the Knoevenagel condensation. This study achieves advancements in the development of super-wettable membranes with outstanding performance in separating emulsions and the as-prepared membranes have the potential to serve as promising candidates for practical oily mixture treatment.

Preparation and properties of bio-based PA56/SiO2–NH2 composite nanofiber membranes for high efficiency oil-water separation

With the continuous development of environmental protection and resource recycling demands, the development of bio-based separation membrane materials has increasingly attracted attention. Bio-based polyamide 56 (PA56), exhibiting excellent hydrophilicity, spinnability, and mechanical properties, is expected to complement and replace traditional separation membrane materials. In this study, the electrospinning preparation and structural control of PA56 nanofiber membranes were achieved through the optimization of PA56 content and mixed solvent ratios. The study found that when the PA56 content was 16 wt% and the formic acid to acetone ratio in the mixed solvent was 8:2, the nanofiber diameter distribution was the most uniform. Building on this, amino-functionalized modified silica (SiO2–NH2) nanoparticles were introduced to prepare PA56/SiO2–NH2 composite nanofiber membranes featuring a cobweb-like nanofiber network and micro-nodule structure. The effects of the addition of SiO2–NH2 nanoparticles on the morphology, structure, and properties of the fiber membranes were studied. The results indicate that the control of the mixed solvent ratio and the addition of SiO2–NH2 nanoparticles led to the formation of a cobweb-like nanofiber network and micro-nano nodular structure on the nanofiber surface, enhancing the hydrophilicity of PA56 nanofiber membranes. The M − 3 membrane with a nanoparticle addition amount of 0.8 wt% exhibited high hydrophilicity and underwater superoleophobic properties, achieving efficient separation of stable oil-in-water emulsions with a separation efficiency of 99.8 %. This work provides a new bio-based membrane material and its preparation method for treating oily wastewater using the membrane separation method.

Nacre-inspired graphene oxide/polyethyleneimine-based ultra-thin heterogeneous superwetting membrane for highly stable separation of oil-in-water emulsions

Since the massive discharge of oily wastewater seriously affects both humans and natural development, the performance of conventional membrane materials in terms of interfacial stability and antifouling in the treatment of surfactant-containing emulsified oily wastewater is a major challenge. In this work, a novel nacre-inspired graphene oxide/polyethyleneimine-based ultra-thin chemically heterogeneous superwetting membrane was fabricated through vacuum-assisted self-assembly and post-modification methods for oil-in-water emulsion separation. The nacre-inspired heterogeneous membrane exhibited superhydrophilicity, underwater superoleophobicity (underwater oil contact angle was 157.7°), excellent crude oil adhesion resistance, high acid/alkaline stability, outstanding salt resistance, and good mechanical properties (Young’s modulus 1391.7 MPa). The heterogeneous membranes showed separation efficiencies of more than 99.9 % for a range of oil-in-water emulsions. The high-value membranes could achieve the permeances of 917–1256 L m−2h−1 bar−1 for pure water and 339.7–577 L m−2h−1 bar−1 for emulsion through a dead-end filter device, with the optimal long-term stable permeance only decreasing by 30.0 % compared to the initial value. After six test cycles, the membrane’s antifouling and self-cleaning properties were enhanced by constructing heterogeneous superwetting properties, and the flux recovery rate remained at 96.5 %. All of these results indicated that this method provides new ideas for the design and fabrication of highly stable and antifouling membrane materials.

An Anchored Fe-Cu LDH onto a Polyvinylidene Fluoride Membrane with Strong Peroxymonosulfate Activation-Induced Degradation of Methylene Blue and Self-Cleaning Property of Oil/Water Separation.

Developing a strong catalytic antifouling membrane to achieve efficient sewage purification has great potential for alleviating water crisis. In this work, we designed and prepared an Fe/Cu-layered double hydroxide (Fe-Cu LDH)-coated polyvinylidene fluoride (PVDF) composite membrane (PVDF/Fe-Cu LDHs) with strong antifouling and activating peroxymonosulfate (PMS) catalytic degradation performance through polydopamine-coordination anchoring and hydrothermal reaction. The results showed that abundant hydroxyl groups of the LDH surface endowed the superhydrophilicity (water contact angle <10°) and underwater superoleophobicity (underwater-oil contact angle >150°) of the membrane surface, which displayed outstanding resistance to crude oil adhesion. With assistance of the LDH surface-bound sulfate radical of the peroxymonosulfate system, the PVDF/Fe-Cu LDH membrane demonstrated robust catalytic degradation performance for the methylene blue (MB) in the dark; the degradation rate constant (k, min-1) reached 0.96. Meanwhile, facing the oily wastewater, the selective wettability and charge effect of LDH of the surface made the PVDF/Fe-Cu LDH membrane realize the separation for the various surfactant-free and surfactant-stabilized emulsions. Importantly, the PMS-activation catalytic produced the ROS (•SO4-,•OH, •O2-, and 1O2), which enhanced the regeneration of the fouled PVDF/Fe-Cu LDH membrane and obtained a high flux recovery ratio in the dark (94.7%) after 10 cycles of separation experiments. Hence, we believed that the PVDF/Fe-Cu LDH membrane can provide inspiration for the development and further practical application of antifouling membranes.

Bioinspired interlaced wetting surfaces for continuous on-demand emulsion separation

Maintaining high separation performance during continuous emulsion separation remains a challenge. Herein, based on biomimetic coupling ideas, hole array interlaced wetting surfaces (HAIWSs) and mastoid array interlaced wetting surfaces (MAIWSs) were prepared by laser processing, electroless silver deposition, thiol modification, and spraying for on-demand emulsion separation. When the separation is going on, randomly moving emulsion droplets are prone to being captured by holes or mastoids due to interlaced wettability. Under this unique interface behavior, the occurrence of filter cake and pore clogging is reduced, thus achieving both high efficiency (∼99.5 and ∼99.3 %). Meanwhile, the high flux can also be maintained (∼3212 and ∼3458 L m−2 h−1). Significantly better than surfaces without pores or mastoid structures. Further, the as-prepared surfaces also exhibit excellent recyclability. After 50 separation cycles, optimized HAIWS and MAIWS still maintained high efficiency (∼96.2 and ∼95.8 %) and high flux (∼3042 and ∼3164 L m−2 h−1), exceeding other surfaces without hole or mastoid structure. Notably, complex physical/chemical cleaning processes are avoided. Besides, even in harsh conditions, HAIWS and MAIWS still maintain excellent stability. The above strategy provides a novel mechanism for effective on-demand emulsion separation and is expected to encourage the creation of new-class separation devices for oily wastewater treatment in industry.

Synthesis And Efficiency Evaluation of Chitosan-Alginate Hydrogel Polyelectrolyte Complex Filter for Treatment of Oil Spillage

Crude oil spills pose considerable environmental concerns thereby demanding the development of effective, sustainable, and eco-friendly remediation solutions. In this study, we synthesized and evaluated the efficiency of a biodegradable polymer filter using sodium alginate and chitosan for the treatment of oil spillage. The sodium alginate-chitosan hydrogel polyelectrolyte complex (SACHPC) filter was synthesized via dipping method using a layer-by-layer self-assembly technique integrated with cotton wool as the filter medium. The efficiency of the filter was evaluated based on flow rate of recovered oil and reusability of the filter. Simulated oil spillage of 0.5 M was subjected to filtration using the SACHPC filter. The flow rate was determined based on the time taken for 1 L of oil to pass through the filter. The SACHPC filter exhibited underwater superoleophobic behaviour with exceptional filtration efficiency (&gt; 98.3%) in acidic, neutral and alkaline conditions (pH 3, 7 and 11). The flow rate of the filter was 120 mL/min, while the third-use filter exhibited a decrease flow rate of 50 ml/min. Moreover, the filter achieved an impressive crude oil recovery rate of 85%. X-ray diffraction analysis confirmed crude oil adsorption in the presence of an amorphous phase while scanning electron microscopy analysis revealed the structural morphology of the SACPHC filter. Overall, the SACHPC filter maintained high filtration efficiency thereby offering a sustainable strategy for oily wastewater purification and oil spill clean-up.

C/N ratio effect on oily wastewater treatment using column type SBR: machine learning prediction and metagenomics study

The sequencing batch reactor has emerged as a promising technology in treating wastewater; however, its application in the treatment of generated water still needs to be explored. This research gap led to the investigation of various carbon-to-nitrogen (C/N) ratios in a column-type sequencing batch reactor (cSBR). The resulting data and model demonstrated that augmenting the SND process with an external carbon source is effective until the C/N ratio reaches 15, ultimately eliminating nitrogen in the produced water. Conversely, a reduced C/N ratio can limit the ability of polyphosphate-accumulating organisms to incorporate carbon into polyphosphate synthesis, thereby decreasing phosphorus removal efficiency within the cSBR. When the C/N ratio ranged from 6 to 8, and the mixed liquor suspended solids concentration was high, the average phosphate removal was approximately 55%, compared to only around 25% when the C/N ratio was less than 6.