Petrochemical Wastewater Treatment Research Articles

Ultrasound‒induced facile synthesis of spinel CoFe2O4‒PAC magnetic nanocatalyst for remediation of hypersaline petrochemical wastewater: Degradation mechanism, biodegradability enhancement and phytotoxicity mitigation

In this study, magnetic CoFe2O4−PAC nanocatalysts were synthesized through facile hydrothermal and co‒precipitation approaches with ultrasonic irradiation, which were used for the treatment of hypersaline petrochemical wastewater (HPCW). When an ultrasound‒induced synthesis process (US@CoFe2O4‒PAC) was used, a more efficient and stable magnetic spinel CoFe2O4‒PAC nanocatalyst was developed. The application of this nanocatalyst as a PMS activator, not only caused eradication of 90.4% of chemical oxygen demand (COD) of a HPCW after 90 min reaction time under the optimum conditions (pH 5−6, catalyst dose 1.0 g/L and 1.0 mM PMS), but also led to marginal leaching of iron (314 μg/L) and cobalt (95 μg/L) from the nanocatalyst. Recycling experiments over five consecutive runs showed a negligible decrease (7.2%) in COD removal efficiency which proved the stability and reusability of magnetic US@CoFe2O4−PAC. Two main mechanisms of adsorption and catalytic oxidation processes (homogeneous and heterogeneous PMS) are involved simultaneously in the PMS/US@CoFe2O4−PAC system, which are responsible for the destruction of refractory contaminants of HPCW through the generation of SO4•‒ and OH• radicals. COD of HPCW was mainly removed through SO4•− radical attack (73.6%) and the biodegradability of HPCW was enhanced dramatically after 90 min reaction time. The germination index (GI) of raw HPCW was increased 17.1 ± 4.2% and 24.3 ± 8.8% after 15 and 90 min reaction time, respectively, even PMS/US@CoFe2O4−PAC system showed less impact on phytotoxicity mitigation. Hence, it can be recommended to dilute the effluent before using for irrigational purpose. The findings of this study present practical significance of spinel US@CoFe2O4−PAC, which is an environment‒friendly catalyst, easy to handle and can sustain long‒term operation for the treatment of recalcitrant hypersaline wastewater and the other potential practical applications.

The treatment of petrochemical wastewater via ozone-persulfate coupled catalytic oxidation: mechanism of removal of soluble organic matter.

Petrochemical wastewater contains a variety of organic pollutants. Advanced oxidation processes (AOPs) are used for deep petrochemical wastewater treatment with distinct advantages, including the complete mineralization of organic substances, minimal residual byproducts, and compatibility with biological treatment systems. This work evaluates the effectiveness of three methods, namely, ozone, persulfate, and O3-PMS (ozone-persulfate) processes, which were compared to remove soluble organic matter. The O3-PMS process offered significant advantages in terms of organic matter removal efficiency. This process involves ozone dissolution in an aqueous persulfate solution, producing a more significant amount of hydroxyl radicals in comparison to single AOPs. The production of hydroxyl radicals and the synergistic effect of hydroxyl radicals and persulfate radicals were investigated. In the O3-PMS process, transition metal ions were added to understand the mechanism of the O3-PMS coupled catalytic oxidation system. The results showed that when the ozone concentration was in the range of 5 ~ 25mg/L, the dosage of persulfate was in the range of 0.01 ~ 0.05mol/L, the dosage of metal compounds was in the range of 0:0 ~ 2:1, and the reaction time was in the range of 0 ~ 2h; the optimum chemical oxygen demand (CODCr) and total organic content (TOC) removal effect was achieved under the coupled system with an ozone concentration of 10mg/L, a persulfate dosage of 0.02mol/L, a 1:2 dosage ratio of between Fe2+ and Cu2+ compounds, and a reaction time of 2h. Under optimal reaction conditions, the rates of CODCr and TOC removal reached 70% and 79.3%, respectively. Furthermore, the removal kinetics of the O3-PMS coupled catalytic oxidation system was analyzed to optimize the removal conditions of COD and TOC, and the mechanism regulating the degradation of dissolved organic matter was explored by three-dimensional fluorescence and GC-MS technology. Thus, O3-PMS coupled catalytic oxidation is an effective process for the deep treatment of wastewater. The careful selection of transition metal ions serves as a theoretical foundation for the subsequent preparation of catalysts for the ozone persulfate oxidation system, and this study provides a suitable reference for removing organic matter from petrochemical wastewater.

Catalytic ozonation with carbon-coated copper-based core-shell catalysts (C/Cu-Al2O3) for the treatment of high-salt petrochemical wastewater

High-salt petrochemical wastewater requires advanced treatment for water reuse due to its high salinity and the presence of refractory organic compounds. Heterogeneous catalytic ozonation is an effective advanced treatment method, with the key to its success lying in the preparation of catalysts. A novel carbon-coated copper-based core-shell catalyst (C/Cu-Al2O3) was successfully prepared. In this work, Al2O3 was used as a carrier and copper as an active component to construct a catalyst with levodopa (L-DOPA) shell and embedded copper sites through the self-polymerization of L-DOPA. The active groups in L-DOPA molecules such as amine and carboxyl groups can be introduced into catalyst and L-DOPA also served as carbon source to reduce Cu(II) to more reactive Cu(I) and Cu(0). Under optimal conditions, its chemical oxygen demand (COD) removal rate for high-salt petrochemical wastewater reached 62.5%. After 20 cycles, its COD removal rate was maintained at above 53%. Electron paramagnetic resonance (EPR) investigations, quenching tests, and degradation experiments of oxalic acid revealed that the generation of embedded copper sites (Cu-O, Cu-N) and the construction of the carbon shell provided the catalyst with rich surface hydroxyl groups and Lewis acid sites, which promoted the decomposition of ozone into hydroxyl radicals (•OH), superoxide radicals (•O2-), and singlet oxygen (1O2) and achieved efficient degradation of organic compounds.

Application of electro oxidation process for treating wastewater from petrochemical with mixed metal oxide electrode

Petrochemicals require a large volume of water for their operation, which results in the production of a large volume of wastewater. Treatment of petrochemical wastewater is an important process before discharging it into the environment. This research examines the treatment of real petrochemical wastewater using the electrochemical oxidation process. Direct anodic oxidation is an effective advanced electrochemical oxidation process (AEOP), with different electrodes using a parallel plate electrochemical reactor. Four types of real wastewater were received from different petrochemical units were treated by AEOP. Real wastewater samples with chemical oxygen demand (COD) concentrations ranging from 20,450 to 52,300 mg/l. The main goal of this research is to make electrodes of Mixed Metal Oxide (MMO), which can reduce the treatment time and electricity consumption for oxidation, greater stability of the surface of the electrodes. Investigation of the rate constant kinetics shows that high COD removal efficiency can be achieved following the pseudo-second order reaction rate (R2 > 98%). When the wastewater pH is less than 5, COD removal efficiency is higher and the treatment process will be successful, which succeeded in removing 79% COD, but in alkaline wastewater, COD reduction efficiency was not satisfactory. The electricity consumption for 79% removal during 6 min was 117 kWh/m3. As a result, due to the very short time of the process (6 min), it can be used as one of the pre-treatment steps of petrochemical wastewater with acidic pH.

The Combination of Electrocoagulation and Enhanced Electrooxidation for the Treatment of Petrochemical Wastewater: Biodegradability Studies

The Combination of Electrocoagulation and Enhanced Electrooxidation for the Treatment of Petrochemical Wastewater: Biodegradability Studies

Treatment of petrochemical wastewater by 3D printed biocarrier integrated activated sludge system: Optimization by response surface methodology, biokinetics, and microbial community

The existence of petrochemicals in petrochemical wastewater (PW) causes it detrimental and complex wastewater. The treatment plant is fed with lower PW concentrations of influent because of the high levels of toxicants. In this study the treatment of PW was carried out with AnoxKaldnes™ (K5) carriers, and 3D printed biocarrier in continuous flow integrated activated sludge system. The integrated activated sludge reactor assisted with K5 biocarrier (IAS-CB) while other assisted with 3D printed biocarrier (IAS-3PB) operated under similar conditions with varying hydraulic retention time (HRT) from 12 h to 24 h and PW concentration from 20 % to 100 % for organic and nutrient removal. The optimized result using response surface methodology (RSM) revealed better performance of IAS-3PB than IAS-CB for organics and nutrient removal. The maximum removal efficiency of total phosphorus (TP), Chemical oxygen demand (COD), and ammonia‑nitrogen (NH4+-N) was 78.4 %, 90.3 %, and 86.2 % in IAS-3PB while 75.2 %, 88.1 %, and 84.2 % in IAS-CB, respectively. Moreover, the RSM predicted optimized conditions revealed higher removal efficiencies with more PW concentration and shorter HRT in IAS-3PB. The IAS-3PB achieved better nitrification rate due to the adherence of Nitrosomonas, Nitrospira and Acinetobacter on 3PB as a biofilm with a higher abundance. However, the abundance of Proteobacteria, and Bacteroidetes were witnessed in IAS-CB. The modified Stover-Kincannon biokinetic model was found to be the best fit for both the reactors for organic and nutrient removal. Thus, these findings can provide solution to petrochemical industry for the treatment of PW with higher loading conditions.

Performance of tubular microbial fuel cells using different industrial wastewater

Microbial fuel cells (MFCs) can potentially ameliorate the extensive use of energy in the biological treatment step of wastewater treatment, among other benefits. This paper investigated the use of MFCs for different types of industrial wastewater using carbon fuel cell electrodes. The MFCs were inoculated with activated sludge and operated with industrial wastewater collected from Kuwait's most common industries (dairy, detergents, petrochemicals, and soft drinks). The results showed that MFCs have successively generated electricity from all industrial wastewater, except for that from the petrochemical industry. The MFCs achieved a maximum power density of 86 mW/m3 (dairy wastewater), 41 mW/m3 (detergents wastewater), 20 mW/m3 (soft drink wastewater), and 1 mW/m3 (petrochemical wastewater). Furthermore, the MFCs achieved an average Chemical Oxygen Demand (COD) removal efficiency of 75 % (dairy wastewater), 44 % (detergent wastewater), 7 % (petrochemical wastewater), and 79 % (soft drink wastewater). Conceivably, these removal rates correspond to bioelectrochemical utilization of the organic matter present in the different types of industrial wastewater to produce energy. Increasing batch duration from 7 to 14 days did not influence nutrients and heavy metals removal. In addition, it was found that the application of MFCs for petrochemical wastewater treatment was influenced by (high COD level = 15,114 mg/L), the content of inhibitive chemicals (such as surfactant, dimethylpolysiloxane, ferric sulfate, and benzalkonium chloride), and the hydrophobicity of the organics leading to deterioration in fuel cell electrode performance, catalyst deactivation, and generally unfavourable microbial growth conditions.

Pollutants removal and connections among sludge properties, metabolism potential and microbial characteristics in aerobic granular sequencing batch reactor for petrochemical wastewater treatment

Petrochemical wastewater contains inhibitory compounds such as aromatics that are toxic to microorganisms during biological treatment. The compact and layered structure and the high amount of extracellular polymeric substances (EPS) in aerobic granular sludge (AGS) can contribute to protecting microorganisms from the harsh environment. This study evaluated the changes in the granule properties, pollutants removal, microbial metabolic potential and molecular microbial characteristics of the AGS process for petrochemical wastewater treatment. Granules treating petrochemical wastewater had a higher SVI30/SVI5 value (0.94) than that treating synthetic wastewater. An increase in bioactivity and EPS secretion with higher bio-polymer composition, specifically the functional groups such as hydroxyl, alkoxy and amino in protein, was observed, which promoted biomass aggregation. The granules also had more than 2-fold higher specific oxygen utilization rate. The AGS-SBR process obtained an average COD removal of 93% during petrochemical wastewater treatment and an effluent bCOD of below 1 mg L−1. No obvious inhibition of nitrification and denitrification activity was observed in the processes attributed to the layered structure of AGS. The average effluent NH4+-N of 5.0 mg L−1 was obtained and TN removal efficiencies of over 80.0% was achieved. Molecular microbial analysis showed that abundant functional genera Stenotrophomonas and Pseudoxanthomonas contributed to the degradation of aromatics and other petroleum organic pollutants. They were enriched with the variation of group behavior while metabolisms of amino acids and carboxylic acids by the relevant functional genera (e.g., Cytophagia) were significantly inhibited. The enrichment of Flavobacterium and Thermomonas promoted nitrification and denitrification, respectively. This research revealed the rapid start-up, enhanced granule structural strength, high inhibition resistance and considerable performance of AGS-SBR for petrochemical wastewater treatment.

Simple preparation of monolithic N-doped electrode for efficient EF remediation of petrochemical wastewater: Performance, degradation pathways, and mechanism of different N-doped positions

Developing metal-free N-doped electrode for efficient electro-Fenton (EF) application is significant for petrochemical wastewater treatment considering the serious water pollution problem that caused by petrochemical industry. Herein, a robust monolithic N-doped electrode was fabricated by simple physical mixing and heating methods using accessible raw materials, and applied in EF system for wastewater treatment. The prepared 3D NC-650 electrode was used as cathode, showing excellent catalytic activity and stability for degradation of typical p-nitrophenol (PNP) pollutant and remediation of petrochemical wastewater. During the EF process, the PNP was completely decomposed via the substitution, oxidation, and ring-opening reactions under the attack of ·OH. The degradation pathways of organics in real wastewater matrix were also revealed based on liquid chromatography-mass spectrometry and three-dimensional fluorescence analysis. According to the degradation experiments, microstructure analysis, and theoretical calculation (molecular electrostatic potential, bond length, and adsorption energy), the possible mechanism of different N-doped positions on the monolithic 3D NC-650 electrode was revealed, in which the graphitic N, edge pyridinic N, and edge pyrrolic N all contribute to enhance the EF activity by accelerating the O2 adsorption, facilitating the H2O2 formation by promotion of *–OOH bond breaking, and promoting the adsorption of organics on electrode surface, respectively. This work illustrates insights into the EF reaction mechanism with the monolithic N-doped electrode, and thus accelerates its application for actual wastewater remediation.

Application of photocatalytic proxone process for petrochemical wastewater treatment

Industrial wastewaters are different from sanitary wastewaters, and treatment complications due to their unique characteristics, so biological processes are typically disrupted. High chemical oxygen demand, dye, heavy metals, toxic organic and non-biodegradable compounds present in petroleum industry wastewater. This study intends to optimize the photocatalytic proxone process, utilizing a synthesized ZnO–Fe3O4 nanocatalyst, for petroleum wastewater treatment. The synthesis of ZnO–Fe3O4 was done by air oxidation and layer-by-layer self-assembly method and XRD, SEM, EDAX, FT-IR, BET, DRS, and VSM techniques were used to characterize the catalyst. Central composite design (CCD) method applied to investigated the effect of pH (4–8), reaction time (30–60 min), ozone gas concentration (1–2 mg/L-min), hydrogen peroxide concentration (2–3 mL/L) and the amount of catalyst (1–0.5 g/L) on the process. In the optimal conditions, biological oxygen demand (BOD5) and total petroleum hydrocarbon (TPH) removal, reaction kinetic, and synergistic effect mechanisms on the process were studied. Based on the ANOVA, a quadratic model with R2 = 0.99, P-Value = 0.0001, and F-Value = 906.87 was proposed to model the process. Based on the model pH = 5.7, ozone concentration = 1.8 mg/L-min, hydrogen peroxide concentration = 2.5 mL/L, reaction time = 56 min, and the catalyst dose = 0.7 g/L were proposed as the optimum condition. According to the model prediction, an efficiency of 85.3% was predicted for the removal of COD. To evaluate the accuracy of the prediction, an experiment was carried out in optimal conditions, and experimentally, a 52% removal efficiency was obtained. Also, at the optimum condition, BOD5 and TPH removal were 91.1% and 89.7% respectively. The reaction kinetic follows the pseudo-first-order kinetic model (R2 = 0.98). Also, the results showed that there is a synergistic effect in this process. As an advanced hybrid oxidation process, the photocatalytic proxone process has the capacity to treat petroleum wastewater to an acceptable standard.

Integrating eco-environmental assessment with energy recovery for petrochemical wastewater treatment technologies: A transition towards green and sustainable management

The petrochemical industry is a significant source of hazardous waste, leading to widespread environmental pollution. For the first time, an integrated approach was employed in the current study to combine life cycle assessment (LCA) coupled life cycle cost (LCC) analysis with waste sludge disposal scenarios to evaluate trickling filter (TF), membrane bioreactor-reverse osmosis (MBR-RO), and integrated fixed-film activated sludge-membrane bioreactor (IFAS-MBR) performance at the individual unit level for the treatment of petrochemical wastewater. The midpoint LCA modeling indicated that the main environmental burdens in the studied systems were freshwater eutrophication (<5.31 kg P eq) and toxicity potentials (<263.16 kg 1,4-DCB). These impacts were primarily attributed to the emissions of zinc, copper, nickel, and the processing of heat and gas. Furthermore, the results of the LCC analysis revealed that the TF system was more cost-effective than the MBR-RO and IFAS-MBR systems. By utilizing the produced biogas for energy provision in the TF system, significant reductions in toxicity potentials and ecosystem impact categories ranging from 26.72 % to 56.69 % were observed. Additionally, the biowaste scenario exhibited lower environmental concerns (<50 %) compared to incineration or landfill. In conclusion, this investigation provides valuable perspectives and a sustainable strategy for future policymaking regarding petrochemical wastewater treatment.

The destiny of microplastics in one typical petrochemical wastewater treatment plant

Microplastic (MP) is a type of emerging contaminant that is verified to be threatening to some organisms. Controlling MP emission from the source is preferred for its refractory characteristic. The petrochemical industry is a possible contributor, responsible for the most plastic production, and wastewater is the most possible sink of MP. This study applied the Agilent 8700 Laser infrared imaging spectrometer (LDIR) to detect MPs in one typical petrochemical wastewater treatment plant (PWWTP). It was determined that the abundances of MPs in the influent and effluent of the target PWWTP were as high as 7706 and 608 particles/L. The primary treatment removed most MPs (87.5 %) with a final removal efficiency of 92.1 %. 23 types of MPs were identified, and Polyethylene (PE), Polypropylene (PP), Silicone resin prevailed in the effluent. All the MPs were smaller than 483.9 μm. All in all, this study preliminarily unveiled the ignorable status of the petrochemical industry in releasing MPs into the water environment for the first time.

Solar light assistance for remediation of hypersaline petrochemical wastewater: kinetics and artificial neural network models

ABSTRACT Nowadays, treatment of xenobiotic and refractory hypersaline petrochemical wastewater (HSPW) has been widely pointed out as one of the main environmental challenges. In the current study, the effectiveness of solar light and sulphate radical advanced oxidation process is evaluated for the remediation of a real phenolic-HSPW. Therefore, the effect of persulphate (PS) concentration, Fe(II) dosage, pH, initial total phenol (TP) concentration, reaction time, temperature and solar radiation intensity were examined. An artificial neural network system also investigated to model the processes. The results showed that solar radiation enhanced dramatically the performance of processes and >99% TP removal was achieved. The efficiency of the processes was followed: summertime solar‒Fe(II)/PS (99.8%) > wintertime solar‒Fe(II)/PS (70.0%) > Fe(II)/PS (26.3%) > sole PS (<5%). The corresponding values for the removal of COD (with the initial concentration of 1016 mg/L) were found 61, 31, 24, and <3%, respectively. According to artificial neural network model, pH and temperature played the most important role for removal of the TP from the HSPW. Finally, our results proved that solar-induced AOP systems are promising novel solution to combat emerging contaminants in petrochemical effluents.

Clogging mechanisms of biological aerobic filter in a petro-chemical wastewater treatment plant: A field study

Clogging reduces the treatment capacity of the Biological Aerobic Filter(BAF). Revealing the cause of clogging is the key to maintaining normal treatment of BAF. In a petrochemical wastewater treatment plant, two identical structure BAF exhibit different clogging situations. Pre-BAF was clogged with slurry while Posterior-BAF was clogged with medium hardening. SEM showed the medium granular of Posterior-BAF were glued by crystal scale. The crystal scale was detected as calcite by XRD. Water quality analysis illustrated that the raw water contained high concentrations of Ca2+ and HCO3−, the calcium carbonate solubility products of the Pre-BAF and Posterior-BAF water were 6.5 × 10−8 and 3 × 10−8, both are over deposition value. The concentration of TOC in the Pre-BAF influent water was 67.8 mg/L, 7 times higher than that in the Posterior-BAF. The calcium content in the Posterior-BAF scaling along the flow direction shows the proportions were 8.2 %, 19.1 % and 30.7 % in the front, middle and back sections respectively. Thermal gravimetric analysis of the crystalline scale illustrated there were organic weight loss peaks in the front section while only calcite peaks in the back section. It is concluded the organic content is the main reason for the clogging difference in the two BAFs. The organic substance exerts an effect on the scale composition and the calcite crystal perfect in the Posterior-BAF.

Structure design and industrial experiment of compact flotation unit for refinery wastewater treatment

The compact flotation unit (CFU) has been widely used in offshore oilfield-produced water treatment with the characteristics of compact structure and high oil removal efficiency. However, there is no published literature talking about CFU’s application in refinery wastewater treatment. In this paper, an innovative designed two-stage series BIPTCFU process diagram for refinery wastewater treatment was proposed. The structural design of the core BIPTCFU with a capacity of 20 m3/h was also carried out. After that, the manufactured industrial prototype of BIPTCFU-III-20 was tested in a SINOPEC petrochemical wastewater treatment plant. The single-factor operation test results show that with the increase of gas-liquid volume ratio, the oil removal efficiency of the BIPTCFU-III-20 increases first and then stabilizes. The reason can be ascribed to the microbubble number density which contributes to the oil removal efficiency. With the increase of inlet water flow rate, the oil removal efficiency first increases and then decreases. The reason is that as the inlet flow rate increases and approaches the rated treatment capacity, a stable swirling flow field is gradually formed in the vessel which benefits to the oil removal performance. While when the inlet water flow rate exceeds the rated capacity, the calculated hydraulic retention time was too short to complete the air flotation process. Under the optimal operation parameters, the oil removal performance of the BIPTCFU-III-20 on refinery wastewater was remarkable, and the average oil removal efficiency was 81.65 % when the inlet oil content was higher (1307 mg/L ∼ 4486 mg/L). While, when the inlet oil content is lower (150 mg/L ∼ 393 mg/L), the average oil removal efficiency was 77.75 %. The effect of low inlet oil content on the oil removal rate is more significant than that of high oil content. Based on the above basic research results, an industrial BIPTCFU with a rated capacity of 100 m3/h was constructed. The remarkable oil removal performance of the refinery wastewater was further verified.

Synthesis of bio-based materials from agricultural residues for treatment of petrochemical wastewater

4-Carboxybenzaldehyde (4-CBA), a major component of purified terephthalic acid wastewater, is toxic to living organisms and required to be removed before the discharge of treated wastewater in a natural water body. In this work, the adsorptive removal of 4-CBA was studied using bagasse fly ash (BFA), a waste product from the sugar industry. The adsorption capacity of BFA was compared with the commercially available adsorbent, granular activated carbon (GAC). A 4-factorial, 5-stage central composite design (CCD) was used to optimize 4-CBA removal and adsorption uptake by BFA using response surface methodology (RSM). The variables considered for the study were pH, adsorbent dose (m), initial concentration (Co) and time (t). At the optimum treatment conditions of pH = 4, m = 9 g/L, Co = 100 mg/L and t = 7.5 h, the removal efficiency and adsorption uptake of 4-CBA on BFA were found to be 79% and 9.9 mg/g, respectively. BET surface area of BFA was determined to be 284 m2/g. A kinetic study was performed using a first- and second pseudo-order model. The adsorption equilibrium data were fitted for various adsorption models. A positive value Delta H^{0} indicates that the adsorption process is endothermic. This study indicated that BFA is a cost-effective adsorbent for the removal of 4-CBA with high adsorption capacity and fast kinetics.Graphical

Removal of formaldehyde pollutant from petroleum industry wastewaters by polymers: A molecular dynamics simulation

Formaldehyde is one of the most widely used chemical pollutants, which is used as a toxic substance in the wastewater from many industrial processes, including oil and petrochemical industries, dyeing, glue and resin making, textile, etc. Therefore, it is necessary to treat the waste produced before entering the environment. Thus, choosing a suitable method that can be used to remove these toxic pollutants is one of the most important challenges in the discussion of wastewater treatment in oil and petrochemical industries. There are various methods to treat these wastes. But surface adsorption can be used as one of the efficient methods to remove formaldehyde from wastewater. In this regard, in this work, the interaction between formaldehyde and polymers has been investigated using the accuracy of molecular dynamics simulation in the simulation of intermolecular interaction. Polymer polypropylene (pp) was represented as the best polymer for removing formaldehyde from wastewater with the highest intermolecular interaction energy. The reported results might present the suitable conditions for the polymers applications for the treatment of petroleum and petrochemical industry wastewater from formaldehyde.

Is the petrochemical industry an overlooked critical source of environmental microplastics?

Microplastics (MPs) are ubiquitous in the environment and have been verified to be harmful to organisms. The petrochemical industry is a possible contributor, for it is the primary plastic producer but is not focused on. In this background, MPs in the influent, effluent, activated sludge, and expatriate sludge of a typical petrochemical wastewater treatment plant (PWWTP) were identified by the laser infrared imaging spectrometer (LDIR). It revealed that the abundances of MPs in the influent and effluent were as high as 10310 and 1280 items/L with a removal efficiency of 87.6%. The removed MPs accumulated in the sludge, and the MP abundances in activated and expatriate sludge reached 4328 and 10767 items/g, respectively. It is estimated that 1440,000 billion MPs might be released into the environment by the petrochemical industry in 2021 globally. For the specific PWWTP, 25 types of MPs were identified, among which Polypropylene (PP), Polyethylene (PE), and Silicone resin were dominant. All of the detected MPs were smaller than 350 µm, and those smaller than 100 µm prevailed. As for the shape, the fragment was dominant. The study confirmed the critical status of the petrochemical industry in releasing MPs for the first time.

Increasing biodegradability of a real amine-contaminated spent caustic problematic stream through WAO and CWAO oxidation using a high specific surface catalyst from petcoke

Different operating conditions of wet air oxidation and catalytic wet air oxidation have been studied for the treatment of highly concentrated methyldiethanolamine wastewater streams from amine units of acid gas recovery in petrol refineries. These units occasionally generate streams of high methyldiethanolamine content that require special actions to avoid undesirable impacts on the downstream biological process of the petrochemical wastewater treatment plant due to its inhibition effect. The wet air oxidation treatment achieved remarkable removals of methyldiethanolamine, sulfides, chemical oxygen demand and total organic carbon (99%, 95%, 65% and 38%, respectively). Likewise, activated petroleum coke materials from the own refinery plant were tested as catalysts in the process. These materials were prepared under different conditions (chemical activating agent and thermal carbonization process). The catalytic wet air oxidation treatment using an activated petroleum coke was able to remove the methyldiethanolamine at milder operation conditions keeping a similar performance in terms of wastewater treatment removals as compared to the non-catalytic experiments. This technology significantly increased the biodegradability of the treated effluents ranging from 25 to 70 % due to the formation of more biodegradable substrates (acetic acid and ammonium) for further biological treatment.

Petrochemical wastewater treatment device based on ultrasonic demulsification and rotating packed bed

Petrochemical wastewater treatment device based on ultrasonic demulsification and rotating packed bed