Industrial Wastewater Treatment Processes Research Articles

Fault Detection in Industrial Wastewater Treatment Processes Using Manifold Learning and Support Vector Data Description

Fault Detection in Industrial Wastewater Treatment Processes Using Manifold Learning and Support Vector Data Description

Using a novel bio-based cationic flocculant for food industry wastewater treatment

Wastewater from the food industry is considered harmful to human health and aquatic life, as well as polluting water and soil. This research is centered around finding an affordable and easy physicochemical method for dealing with waste generated by the food industry. To accomplish this goal, a new bio-based flocculant called 4-benzyl-4-(2-oleamidoethylamino-2-oxoethyl) morpholin-4-ium chloride was created using sustainable sources, specifically crude olive pomace oil. Its chemical structure was confirmed using various spectroscopic techniques such as FTIR, 1H-NMR, mass spectra, and 13C-NMR. This new bio-based cationic flocculant was combined with alum to act as a coagulant in the waste treatment process. Also, a study was conducted to determine the optimal conditions for the coagulation-flocculation process parameters, namely, pH and alum dosage, on COD and removal efficiency. The results showed that the optimal conditions for flocculation were achieved at pH 5.8, with 680 mg/L alum and 10 mg/L of commercial flocculant dose compared to only 5 mg/L of a new bio-based cationic flocculant. A comparison was made between the new bio-cationic flocculant and a commercial CTAB one for treating wastewater in the food industry. The study found that the new bio-based cationic flocculant was more effective in reducing the chemical oxygen demand, achieving a reduction of 61.3% compared to 54.6% for using a commercial cationic flocculant. Furthermore, using a new bio-based cationic flocculant costs only 0.49 $/g, which is less than the present cationic flocculant, which costs 0.93 $/g. The adoption of this new flocculant provides a sustainable alternative to existing industrial wastewater treatment processes

Al nanoparticles coated with polyaniline and functionalized modified multi-walled carbon nanotubes (MWCNT) for removal of Ni2+ and Zn2+ from a simulated industrial effluent

Heavy metals are one of the most important environmental pollutants. One of the methods of absorbing heavy metals from industrial wastewater is the use of synthesized nanosorbents. The high cost and low efficiency of some common industrial wastewater treatment processes have created limitations. One of the interesting methods is the absorption process by carbon nanotubes as a new method. The present research aims to investigate the application of Al nanoparticles coated with polyaniline and functionalized modified multi-walled carbon nanotubes (MWCNT) for removal of Ni2+ and Zn2+ from a simulated industrial effluent. In the present study, the effect of absorption process time, pH, nickel and zinc ion dose, adsorbent dose and temperature on the efficiency of heavy metal absorption was investigated. The concentration of metal ions was measured using the ICP model ES-710. FTIR spectra for modified MWCNT nanotubes and polyaniline-coated alumina nanoparticles were recorded before and after adsorption using a PerkinElmer Spectrum One FTIR vacuum oven. X-ray diffraction patterns were obtained by XRD Rigaku Ultima IV, Japan, and SEM and TEM micrograph analysis were performed by FESEM TESCAN MIRA 3 and PHILIPS CM300, respectively.The maximum removal efficiency of nickel and zinc cations using nano alumina coated with polyaniline was obtained at pH 10 and 8, respectively. The maximum removal percentage of these two metal ions using functionalized MWCNTs can also be obtained at pH 7 and 8. The optimal concentration of metal ions for the highest removal efficiency of studied cations using surface modified alumina nanoparticles and functionalized MWCNT was obtained at 800 mg/L and 100 mg/L, respectively. In addition, the adsorption efficiency decreased with increasing process temperature. The obtained results showed that surface MWCNT with carbonyl, carboxyl and hydroxyl functional groups together with alumina nanoparticles modified by polyaniline can be considered as a potential adsorbent for absorbing nickel and zinc cations from simulated industrial effluents.

Comparative study of eriochrome black T (EBT) dye adsorption utilizing direct growth of cost-effective efficient materials: S-doped ZnO nanoparticles, ultrathin nanoflakes, and nanowalls

In the present studies, zinc oxide (ZnO) nanoparticles were synthesized by the non-aqueous sol-gel route and incorporated with diverse amounts of the nonmetal element like sulfur with different concentration (1, 2, 4, and 6 wt%). Furthermore, the physicochemical properties of all synthesized nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), N2 adsorption/desorption isotherms, and ultra violate visible (UV-Vis) absorption spectra. Powder XRD analysis shows the formation of hexagonal wurtzite phase of ZnO and the incorporation of S atom in ZnO lattice was confirmed by the XPS analysis. FESEM results reveal that the synthesised S-doped (2, 6 wt%) ZnO samples possess the growth of 1D ultra-thin nanoflakes with sharp edge and vertically aligned 1D thin nanowalls morphology. Moreover, UV-Visible transmission spectral studies showed that the optical energy band gap of ZnO NPs were reduced by S doping. After that, pure ZnO, 1, 4, and 6 wt% S-containing ZnO samples were examined as for adsorption study of eriochrome black T (EBT) dye. Among the S-containing samples, 50 mg of the adsorbent, doped with 4 wt% S (4 wt% S-ZnO) could adsorb up to 95.13 % of EBT dye (15 ppm) in 90 min. Therefore, such a sulfure doped ZnO samples in the form of nanoparticles (NPs), nanoflakes (nanosheets) as well as nanowalls could be used as a promising material for the application in industrial wastewater treatment processes.

Benchmarking of industrial wastewater treatment processes using a complex probabilistic hesitant fuzzy soft Schweizer–Sklar prioritized-based framework

The objective of this research work is to effectively handle the intricate and uncertain nature of decision-making in the context of industrial wastewater treatment. The prioritization of wastewater treatment is of utmost importance in order to save the environment, promote human health, ensure adherence to legal regulations, conserve resources, and foster overall sustainability. The demand for efficient and sustainable wastewater treatment processes is increasing globally, but selecting appropriate treatment technologies for industrial effluents is challenging due to its complex nature. Our study aims to provide a systematic framework for evaluating and selecting treatments based on efficacy, affordability, and environmental impact. Aggregation operators are one of the fundamental ideas in the framework of information fusion for addressing real-life problems. Numerous scholars have made significant contributions to the development of aggregation operators specifically designed for multi-parameter decision-making (MPDM) whenever circumstances are characterized by uncertainty. Regrettably, the current operators can only be employed within strict limits and constraints. Therefore, this research formulates novel prioritized aggregation operators that alleviate the restrictive constraints associated with the current operators. After this, we present a new methodology that combines the Schweizer–Sklar prioritized aggregation operators with a complex probabilistic hesitant fuzzy soft framework. For this purpose, we develop the averaging aggregation operators and geometric aggregation operators. Following that, we proceed to examine the theorems and properties associated with them by providing rigorous proofs. Then, we develop a novel decision-making technique with a numerical example based on the wastewater treatment process. Through this novel technique, the best process is the activated sludge process. We perform the validity tests to evaluate the feasibility and effectiveness of MPDM techniques.

Pangenome-Scale Mathematical Modelling of ANAMMOX Bacteria Metabolism

Removal of fixed nitrogen compounds such as ammonium and nitrite from wastewater is of critical importance for balancing the nitrogen cycle and protecting aquatic environments from eutrophication. ANaerobic AMMonium OXidising (ANAMMOX) bacteria have recently been employed for fixed nitrogen removal purposes in wastewater treatment processes. These specialised bacteria convert ammonium and nitrite into nitrogen gas anaerobically, thereby reducing the amount of energy required for aeration in conventional wastewater treatment processes. However, slow growth rates of ANAMMOX remain a major obstacle towards their widespread use in industrial wastewater treatment processes. Thus, a pangenome-scale, constraint-based metabolic model, iRB399, of ANAMMOX bacteria has been developed to design strategies for accelerating their growth. The main metabolic limitation was identified in the energy metabolism of these bacteria, concerning the production of ATP. The extremely low efficiency of the electron transport chain combined with very high growth-associated maintenance energy is likely to be responsible for the slow growth of ANAMMOX. However, different ANAMMOX species were found to conserve energy using a variety of different redox couples, and the modelling simulations revealed their comparative advantages under different growth conditions. iRB399 also identified dispensable catabolic reactions that have demonstrably beneficial effects on enhancing the growth rates of ANAMMOX bacteria. Thus, the pangenome-scale model will not only help identify and overcome metabolic limitations of ANNAMOX bacteria, but also provide a valuable resource for designing efficient ANNAMOX-based wastewater treatment processes.

Evaluation of the Effect of Microalgae Chlorella vulgaris on the Performance of Membrane Bioreactor for Industrial Wastewater Treatment

Water pollution, especially from industry, is a problem that continues to emerge and even get worse. Rising sludge events often occur in industrial wastewater treatment processes. Process engineering with the addition of microalgae is proposed in this study to overcome the occurrence of rising sludge and improve wastewater quality based on dissolved oxygen levels. The control variables used were MLSS 1000 mg/L, microalgae Chlorella vulgaris 106 L, and urea and TSP 1,75 kg each. The dependent variable is rising sludge and DO levels while the independent variable is time. This research went through several stages, namely seeding microalgae, seeding microalgae into activated sludge in MBBR, experimenting with combining microalgae and activated sludge in MBBR, and installing ultrafiltration membranes with a WWTP capacity of 150 m3/day. The addition of microalgae in the MBBR process has a positive impact in improving the quality of industrial wastewater, which is characterized by the absence of rising sludge and DO levels exceeding the minimum threshold.

Shifting paradigms in PFAS resin removal with biomaterial alternatives

BackgroundPer- and polyfluoroalkyl substances (PFAS) are synthetic chemicals prevalent in various consumer products for their resistance to heat, water, and oil. These "forever chemicals" are environmentally persistent and can accumulate in living organisms, leading to health risks such as cancer and hormone disruption. Environmental concerns stem from their longevity and bioaccumulation potential. Mitigation strategies for PFAS contamination are complex and multifaceted, involving regulatory actions, pollution control, and technological innovations. On the regulatory front, efforts are being made to limit the production and use of certain PFAS, as well as to establish guidelines for acceptable levels in water and soil. From a pollution control perspective, there is a push towards preventing PFAS from entering the environment through improved industrial practices and wastewater treatment processes. Technologically, research focuses on developing effective methods for PFAS removal and destruction, such as advanced filtration systems, adsorbents, and high-temperature incineration. Addressing the PFAS challenge is crucial for environmental protection and public health, necessitating ongoing research and technological development to manage and remove these contaminants. MethodsTraditional approaches to extracting or reducing PFAS resins typically involve chemical treatments that, while effective, come with significant drawbacks. These methods are not only expensive and energy-intensive, but they also pose environmental risks due to the potential release of harmful by-products. As the environmental impact of these conventional methods becomes more apparent, there is an increasing urgency to explore and adopt more sustainable and less harmful alternatives. In the pursuit of such alternatives, our research has explored the possibility of a fundamental change in strategy, advocating for the use of environmentally benign biomaterials in the removal of PFAS resins. This green chemistry approach focuses on harnessing naturally derived polymers, which offer a promising avenue for PFAS mitigation with potentially lower ecological footprints. Specifically, our review has identified several carbohydrate-based polymers that exhibit a strong affinity for PFAS chemicals. Cellulose, the most abundant organic polymer on Earth, along with starch and dextran, has been found to possess qualities conducive to the adsorption and removal of PFAS substances. These materials are not only renewable and biodegradable but also present a cost-effective option compared to their chemical counterparts. Significant findingsOur expanded review aims to further investigate the mechanisms through which these biomaterials interact with PFAS compounds, optimize their application in real-world scenarios, and evaluate the lifecycle impact of such green alternatives. The goal is to develop a sustainable PFAS mitigation methodology that can be readily integrated into existing industrial processes, reducing the reliance on traditional chemical treatments and their associated environmental challenges.

Pemanfaatan Limbah Faba (Fly Ash Bottom Ash) Pltu Karangkandri Sebagai Adsorben Pengolahan Limbah Batik Di Desa Kutawaru Cilacap

In this modern era, many technologies are increasingly advanced and industrial developments are increasing, resulting in waste that can contaminate water. The purpose of this study was to determine the best adsorbents from fly ash and bottom ash and to determine the effect of filtration time on the decrease in content, color, BOD5, COD, TSS and pH in the Cilacap batik fabric industrial wastewater treatment process. The steps taken in this study were to find the best filtration time from variations of 60, 120, 180 minutes on fly ash and bottom ash adsorbents and to determine the best adsorbents from fly ash and bottom ash. The results of the color, BOD5, COD, TSS and pH tests showed that the most optimum adsorbent was fly ash, which produced the highest percentage reduction in color content at 60 minutes filtration time of 34.1%, the highest percentage reduction in BOD5 levels at 180 minutes of 69, 5%, the highest percent reduction in COD levels at 120 minutes was 71.5%, the highest percent reduction in TSS levels at 180 minutes was 69.1% and a neutral pH was produced. Analysis of the results of the most optimum time is the filtration time of 180 minutes where the results of filtration using bottom ash adsorbents show the highest percentage reduction in BOD5, COD, TSS levels of 55.4%, 55.3%, 20.4%.

Efficacious elimination of salts from a convoluted ethylene glycol-water solution employing nanofiltration membranes

ABSTRACT In the current scientific studies, a flat-sheet module pilot plant with an HPP-200 nanofiltration membrane was employed to process an ethylene glycol-water mixture from Jayshree Chemicals, Ankleshwar, India, that contained a significant amount of sodium sulfate. The membrane clogged due to degradation fueled by the excessive salt concentration. Hence, the solution was treated because it was diminished, and the impact of dilution was investigated. Consequently, fouling occurs due to increased flux and reduced concentration polarization. 294, 490, and 784 Kpa pressures were applied to the solution. With the dilution factor, the flow rises while the rejection decreases. Rejection rates range from 97% for membrane plugging without dilution to 92% for five folds and 85% for ten folds dilution. The efficacy of chemical cleaning was investigated using 2% solutions of citric acid and ethylenediamine tetra acetic acid (EDTA). Fourier-transform infrared (FTIR) spectroscopy analysis revealed alterations in membrane structure resulting from interactions with the sodium sulfate feed solution. Scanning Electron microscope (SEM) analysis showed substantial fouling on the membrane surface, which was successfully eliminated through chemical cleaning process. The implementation of dilution and pressure control strategies demonstrated efficacy in the mitigation of fouling phenomena and the enhancement of membrane performance. The efficacy of EDTA in flux recovery (69.84%) was superior to that of citric acid (55.77%) during chemical cleaning processes. These findings have potential to facilitate the implementation of nanofiltration technology in industrial wastewater treatment processes on commercial scale.

Direct fabrication of metal-free graphene nanohairs/polyimide heterojunction for the highly efficient photocatalytic degradation of industrial dyes

A single-step three-dimensional graphene nanohairs/polyimide heterojunction (GPH) is fabricated using a CO2 laser-assisted method. An optimization process has been systematically carried out to obtain high-quality graphene nanohairs on polyimide. The obtained GPH was characterized by X-Ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. Using the fabricated GPH as a photocatalyst, the photocatalytic degradation of three industrial dyes namely, methyl orange (MO), methylene blue (MB), and Rhodamine B (RhB), was studied under UV irradiation. The decolorization of the samples was studied by UV–vis absorbance spectrometer. Starting from 5 ppm dye solutions with GPH, the degradation efficiencies of 97 % for MO in 60 min, 98 % for RhB in 90 min, and 88 % for MB in 170 min, were achieved. Furthermore, the stability of GPH was evaluated and after five runs, the degradation efficiency of MO, RhB and MB is decreased to 85 %, 91 % and 75 % from 98 %, 97 %, and 88 %, respectively. The mechanism for the degradation of dyes using GPH was proposed. The simple and feasible fabrication of GPH with excellent photocatalytic dye degradation efficiency would create the new insight into the flexible heterostructures for degrading the industrial wastewater treatment process.

Efficient photocatalytic degradation of tetracycline using magnetic biochar derived by iron-rich sludge.

Industrial wastewater treatment processes produce a large quantity of iron-rich sludge due to the extensive utilization of iron salt reagent. Reuse of iron-rich sludge is an attractive route for excess sludge disposal and management. In this study, sludge-derived magnetic photocatalyst was prepared using industrial iron-rich sludge as raw materials for the first time. The photocatalytic degradation system constructed by the sludge-derived photocatalysts were evaluated using tetracycline (TC) as the target contaminant, achieving a high degradation rate of 98.3% within 5 h under optimal conditions. Major reactive oxygen species in the photocatalytic systems were investigated using radical quenching experiments and electron paramagnetic resonance spectroscopy. The results suggested that •OH and O2•- were activated by photogenerated electrons and holes, respectively. Moreover, bound persistent free radicals induced by quinone-like structure in sludge-derived biochar were the predominant factors affecting radical 1O2 formation under the light irradiation. The reactive oxygen species of •OH, O2•-, and 1O2 played main roles in the degradation of TC. The used magnetic biochar can be effectively separated and recovered in aqueous solutions by the magnetism. This method provides a new cost-effective strategy for antibiotics removal from aqueous solution.

Occurrences and fates of per- and polyfluoralkyl substances in textile dyeing wastewater along full-scale treatment processes

Industrial wastewater is a substantial source of per- and polyfluoroalkyl substances (PFASs) in the environment. However, very limited information is available on the occurrences and fates of PFASs along industrial wastewater treatment processes, particularly for the textile dyeing industry where PFASs occur extensively. Herein, the occurrences and fates of 27 legacy and emerging PFASs were investigated along the processes of three full-scale textile dyeing wastewater treatment plants (WWTPs) based on UHPLC−MS/MS in combination with self-developed solid extraction protocol featuring selective enrichment for ultrasensitive analysis. The total PFASs ranged at 630-4268 ng L−1 in influents, 436-755 ng L−1 in effluents, and 91.5-1182 μg kg−1 in the resultant sludge. PFAS species distribution varied among WWTPs, with one WWTP dominated by legacy perfluorocarboxylic acids while the other two dominated by emerging PFASs. Perfluorooctane sulfonate (PFOS) was trivial in the effluents from all the three WWTPs, indicating its diminished use in textile industry. Various emerging PFASs were detected at different abundances, demonstrating their use as alternatives to legacy PFASs. Most conventional processes of the WWTPs were inefficient in removing PFASs, especially for the legacy PFASs. The microbial processes could remove the emerging PFASs to different extents, whereas commonly elevated the concentrations of legacy PFASs. Over 90% of most PFASs could be removed by reverse osmosis (RO) and was enriched into the RO concentrate accordingly. The total oxidizable precursors (TOP) assay revealed that the total concentration of PFASs was increased by 2.3-4.1 times after oxidation, accompanied by formation of terminal perfluoroalkyl acids (PFAAs) and degradation of emerging alternatives to various extents. This study is believed to shed new light on the monitoring and management of PFASs in industries.

Electromagnetic field-enhanced novel tubular electrocoagulation cell for effective and low-cost color removal of beet sugar industry wastewater

The treatment of real beet sugar mill effluent by a modified electrocoagulation process is proposed. An innovative design of an electromagnetic field-enhanced electrochemical cell consisting of a tubular screen roll anode and two cathodes (an inner and outer cathode) has been used. Different parameters have been investigated including current density, effluent concentration, NaCl concentration, rpm, number of screen layers per anode, and the effect of addition and direction of an electromagnetic field. The results showed that, under the optimum conditions, current density of 3.13 A/m2, two screens per anode, NaCl concentration of 12 g/l, and rotation speed of 120 rpm, the percentage of color removal was 85.5% and the electrical energy consumption was 3.595 kWh/m3. However, the presence of an electromagnetic field distinctly enhanced the energy consumption and the color removal percentage. Numerically, applying the magnetic field resulted in performing a color removal efficiency of 97.7% using a power consumption of 2.569 KWh/m3 which is considered a distinct achievement in industrial wastewater treatment process. The strong enhancement in color removal using a low power consumption significantly reduced the required treatment cost; the estimated treatment cost was 0.00017 $/h.m2. This design has proven to be a promising one for the continuous treatment of beet sugar industrial effluents and to be a competitor to the currently available techniques.

Converting sludge to slag through a high temperature slagging co-gasification process: An evaluation based on a demonstration trial and life cycle assessment

A variety of sludge-based waste materials with distinctive physical and chemical characteristics are co-treated with municipal solid waste (MSW) in a demonstration-scale high-temperature slagging gasifier. The waste materials tested include dewatered sewage sludge (originated from industrial and municipal wastewater treatment processes, respectively), dried sewage sludge, sludge incineration ashes, and waterworks sludge (originated from freshwater treatment process). Up to 49.5% by mass of dried sewage sludge is successfully co-gasified with MSW and up to 89.5% of the solid residues from the gasification process is recovered as reusable slag and recyclable metals. Despite feeding of various waste mixtures, stable operation of the slagging gasifier is achieved with the proper control of the temperature profiles inside the gasifier, the melting of inorganic residues, smooth discharge of the molten slag, and effective flue gas emissions control. Various types of waste-derived slag are characterized to evaluate their potentials to be applied as sustainable construction materials. Toxicity characteristic leaching procedure (TCLP) and compliance batch leaching test results indicate that the sludge-derived slag is environmentally safe with very low pollution potential. In addition, life cycle assessment (LCA) is performed to comprehensively evaluate the treatment of sludge-based waste materials via slagging co-gasification technology. These findings reveal the promising potentials of converting sludge to slag through the high temperature slagging gasification process based on both engineering and environmental aspects, as well as the possible areas for further advancement in the future.

Strontium hexaferrite microspheres: Synthesis, characterization and visible-light-driven photocatalytic activity towards the degradation of methylene blue dye

Methylene blue (MB) is a cationic dye that is utilized in many industrial applications and produces wastewater that leads to water pollution. Hence, in the present study, M-type magnetic strontium hexaferrite (SrFe12O19) microspheres were prepared using the chemical co-precipitation method and used as a magnetic photocatalyst to degrade the MB dye solution. The prepared SrFe12O19 photocatalyst was characterized using various physicochemical techniques. The SrFe12O19 microspheres showed 90.2% of degradation efficiency towards the photocatalytic degradation of MB dye. Further, the as-synthesized photocatalyst has proved to have superior recycling ability without any changes in the phase of the photocatalyst up to three cycles. These findings showed the SrFe12O19 microspheres could be a potential photocatalyst for the degradation of MB dye in industrial wastewater treatment processes.

Pollution and treatment of industrial waste water

Every year, a massive amount of wastewater is discharged into water bodies from various industries, and numerous processes are used to treat wastewater to reduce the number of pollutants. Industrial wastewater can be very different from sewage in terms of its discharge patterns and compositions. The overall scenario is not different for Bangladesh a developing country. Hence, the industrial wastewater treatment process has undergone modification as time passes newly discovered dangerous substances in the industrial wastewater treatment process worldwide. Multiple methods including conventional and advanced methods are upheld in this present paper with advantages and disadvantages also illustrated there. Besides, the potential for integrating two or more technologies to enhance treatment efficiency is also addressed. Considering low cost as well as maintenance purposes, among all the methods, hybrid or integrated technologies are found effective to reduce the contamination level of wastewater.

Methylene Blue Dye Wastewater Treatment Based On Tertiary Stage of Industrial Wastewater Treatment Process: A Review

Methylene blue (MB) is frequently used in the textile, rubber, plastics, leather, pharmaceutical, cosmetic, and food industries. As a colouring and staining agent, MB is reported as one of the most studied dyes involving degradation and photocatalytic activity. Unfortunately, the discharge of waste from the mentioned industries contains residues of dyes, whereby the presence of a very low concentration of dyes can be highly visible. Discharging the waste without suitable treatment can cause many complications for the environment and human health. Due to that reason, the control of dye wastewater has become the most challenging task. Therefore, this review article will be focused on the MB treatment process, especially membrane filtration technology involving a pressure-driven membrane process, which is reported to be the most efficient method to treat MB dye wastewater.

POSSIBLE USE OF LASERS FOR CLEAVAGE OF PHENOLS TILL BASE SUBSTANCES (REVIEW)

The purpose of this review article is to explain the hazards of phenol and phenol compounds to human health and the environment. To describe where and how phenol and its compounds occur, especially in industrial effluents. To study the possibility of using laser technologies for phenol cleavage, as well as for the treatment of industrial wastewater from phenol compounds. Removal of phenol and its compounds using biological wastewater treatment process is widely used worldwide. This method is cost-effective and environmentally friendly. On the other hand, exceeding the tolerable phenol concentration, which is individual for each biological treatment plant, may result in severe intoxication and lead to death of activated sludge system. Thus, the biological treatment process of industrial wastewater is halted until the phenol concentration is reduced to an acceptable level and the microorganisms have time to recover. Such a procedure can be time consuming and unpredictable due to the susceptibility of microorganisms to changing conditions. Based on this, sources of literature have been studied that could help to understand which laser equipment can be used to cleave a phenolic compound or benzene ring to simpler compounds.

Use of sewage sludge biochar as a catalyst in production of biodiesel through thermally induced transesterification

Sewage sludge (SS) is a residual/semi-solid material produced from industrial and municipal wastewater treatment processes. SS contains a high content of lipids and earth alkaline metals that can be used as catalysts for various chemical applications; however, its valorization has rarely been the focus of research. This study demonstrates that SS could be a promising raw material for biodiesel production and a biochar catalyst to promote the reaction kinetics of alkylation. Thermally induced transesterification of the SS extract (SSE) was performed in comparison with the conventional homogeneous reaction. SS biochar was fabricated via pyrolysis. The highest yield (33.5 wt.% per SSE) of biodiesel production was achieved in 1 min of reaction at 305 °C via thermally induced transesterification in the presence of SS biochar, while the yield of biodiesel from (trans)esterification with 5 wt.% H2SO4 was less than 1% even after 24 h. The reaction kinetics (< 1 min) of thermally induced transesterification was extraordinarily faster than that of conventional transesterification (3–24 h). The porous structure and high content of alkaline species in the SS biochar expedited the reaction kinetics. Consequently, the integrated/hybridized process for thermally induced transesterification and pyrolysis of the solid residue of SS was experimentally proved for the valorization of SS in this study. Considering that SS is being disposed of as a waste material and generates toxic chemicals in the environment, its valorization into value-added biodiesel and a catalyst could be an environmentally benign and sustainable technique.Graphical