Eco-friendly Wastewater Treatment Research Articles

Synthesis and characterization of La-doped SnO2 nanoparticles with different shape: A comprehensive study on morphology, structure, and photocatalytic efficiency for eco-friendly wastewater treatment

New controllable synthetic approach to obtain of La-doped SnO2 nanoparticles based on the combination of co-precipitation method with post synthetical hydrothermal treatment has been developed. Nanoparticles with various shape (3 nm spheres and 5 nm cubes) and structural parameters, i.e. different amount of oxygen vacancies and defects, and different dopant concentrations of 11 mol% and 33 mol% were fully characterized using XRD, FTIR, XPS and Raman spectroscopy, TEM, SSA evaluation, optical absorption spectra study, luminescence spectroscopy, including quantum chemical calculations.It was shown that hydrothermal treatment (240 °C during 6 h) promotes nanoparticle growth via the mechanism of oriented attachment. Original computational approach based on the calculation of interaction energies between ions and crystal facets was engaged to study the growth process.The presence of intrinsic photoluminescence (406, 414, 438, 460, 500 and 676 nm) for all obtained samples was established, determined by a complex set of different parameters for sub-10 nm nanoparticles.Photocatalytic efficiency of 95 % on the example of methylene blue under commercially available LED lamp described via quantum chemical modelling and tested on the example of a colorless antibiotic solution. A clear dependance of the morphological and structural parameters on the photocatalytic properties has been obtained and studied in detail.Novel concept based on a combination of chemical and computational method, for effective visible-light driven photocatalyst synthesis with potential antibacterial properties for complex eco-friendly wastewater treatment was proposed.

An attempt to augment performance of machine learning models in a pilot-scale urban wastewater treatment system

The challenge we face is striking a balance between ensuring the standards for wastewater treatment processes and minimizing energy consumption. As such, accurate predictive models become critical. With machine learning algorithms having the ability to discern relationships between inputs and outputs, broad interest has been shown in their applications in wastewater treatment. A key research focus is on effectively adjusting these generic machine learning algorithms to adapt to frequent fluctuations of water quality, inflow volume, and environmental variations. This study developed a Nonlinear Autoregressive neural network (NARX) model having an adaptive real-time updating module to predict the ammonium concentration in the treated effluent. The model has exhibited high predictive accuracy on the testing data, achieving an R2 value of 0.997. By incorporating an adaptive real-time updating module, the model's capability to predict effluent ammonium concentration on novel data sets has been significantly improved, with the R2 value for these predictions increasing from an initial 0.918 to a more refined range of 0.966 to 0.984. Our findings confirm that integrating real-time updating capabilities with machine learning algorithms substantially improves the stability and predictive performance of the models. These outcomes will prompt a broader integration of artificial intelligence in the domain of environmental engineering, which shall foster the implementation of more accurate and eco-friendly wastewater treatment strategies.

Optimising coagulation/flocculation using response surface methodology and application of floc in biofertilisation

Abstract Aquaculture effluent generation, an environmentally crucial process requires effective treatment. Simple methods like coagulation and flocculation are considered effective. In this study, chitosan from Black tiger shrimp, Penaeus monodon, was used to remove ammonia (NH3) and turbidity. Response surface methodology-optimised dosages (5.00, 12.50, and 20.00 mg·L−1), pH (5.00, 6.25, and 7.50), and settling times (5.00, 7.50, and 30.00 min) were applied. Water spinach, Ipomea aquatica, received an application for organic fertiliser after the nutrient status of the recovered floc was later determined. Results showed that at a dose of 16.25 mg·L−1, a pH of 7.5, and a settling time of 17.5 min, chitosan cleared 92.16% of the turbidity. After 30 min of settling, 84.42% of the NH3 was eliminated at 5 mg·L−1 and 7.5 pH. Both macronutrients (P, K, N, Mg, and Ca) and micronutrients (Co, Cu, Fe, Mn, Ni, Se, and Zn) are present in the newly discovered floc. Floc had safe low Pb and Ni levels. Plants treated with floc showed superior growth compared to those with commercial liquid fertiliser, confirming nutrient absorbability. Conclusively, this study provides an eco-friendly wastewater treatment method.

Eco-friendly wastewater treatment using a crab shell-based liquid bio-coagulant: Multi-criteria decision analysis related to different pollutants separation

The protein-rich liquid resulting from the deproteinization step of the chitin/chitosan production process is proposed as a novel wastewater bio-coagulant. The raw material for producing the bio-coagulant is the crab shell contained in discarded fishery by-products. The protein content of the liquid, determined by OPA assay, was 31.6 mg/L. FTIR spectra proved the presence of chitin, and SEM images showed the presence of a nanoparticulated chito-protein complex in the liquid. Coagulation tests were performed with fisheries wastewater, in which the influence of different parameters, such as the bio-coagulant dose, the pH, the agitation speed, and the settling time, on the effectiveness of the bio-coagulant were investigated. Since different parameters with values in wide ranges may affect the fisheries wastewater treatment by the use of the new liquid bio-coagulant, a multicriterial optimization analysis based on Box-Behnken and response surface method (RSM) was applied. The optimal removal degrees, in terms of turbidity (98.91%), BOD5 (92.05%), and COD (78.92%) were achieved at a bio-coagulant dosage of 17.5 mL/L of fish processing wastewater (FPW) at pH 11.3 and temperature of 25°C. A good fit resulted from the experimental data, the Box-Behnken regression models, and response surface-calculated data. The results revealed new bio-coagulant effectiveness similar or superior to the commonly used chemical coagulants (ferric chloride, aluminum sulfate) and even to commercial chitosan. The obtained data indicate that the new natural liquid bio-coagulant is environmentally friendly and suitable for fisheries wastewater treatment.

Trace Co(II) triggers peracetic acid activation in phosphate buffer: New insights into the oxidative species responsible for ciprofloxacin removal

Peracetic acid (PAA) emerges as a promising disinfectant and oxidant applied worldwide, and its application has been broadened for advanced oxidation processes (AOPs) in wastewater treatment. Current studies on transition metal-activated AOPs utilized relatively high concentrations of catalysts, leading to potential secondary pollution concerns. This study boosts the understanding of reaction mechanism in PAA activation system under a low-level concentration. Herein, trace levels of Co(II) (1 μM) and practical dosages of PAA (50–250 μM) were employed, achieving noticeable ciprofloxacin (CIP) degradation efficiencies (75.8–99.0%) within 20 min. Two orders of magnitude of the CIP’s antibacterial activity significantly decreased after Co(II)/PAA AOP treatment, which suggested the effective ecological risk control capability of the reaction system. The degradation performed well in various water matrices and the primary reactive species is proposed to be CoHPO4-OO(O)CCH3 complexes with scavenging tests and electron paramagnetic resonance tests. The degradation pathway of fluoroquinolones including piperazine ring-opening (dealkylation and oxidation), defluorination, and decarboxylation, were systematically elucidated. This study boosts a comprehensive and novel understanding of PAA-based AOP for CIP degradation.

A sustainable green solution to domestic sewage pollution: Optimizing floating wetland treatment with different plant combinations and growth media

Water quality degradation poses a global threat, with surface water resources bearing the brunt of pollution from various sources, including inadequately treated wastewater discharged from industrial and commercial processes. This discharge introduces a wide range of pollutants, compromising surface water quality and potentially contaminating groundwater. Floating Wetland Treatment (FWT) systems, particularly utilizing affordable and easy-to-construct bamboo rafts, emerge as a promising eco-technology offering a sustainable solution for rehabilitating water bodies polluted with inadequately treated domestic sewage. Research exploring the combined remediation potential of different plant combinations remains limited, although several studies demonstrate the efficacy of individual plant species in FWT systems. This study addresses this gap by evaluating the effectiveness of three terrestrial plant combinations (Canna indica, Chrysopogon zizanioides, and Hibiscus rosa-sinensis) supported by bamboo rafts in treating domestic wastewater. Among FWT methods, systems utilizing bamboo as floating rafts stand out due to their affordability, ease of construction, and adaptability to diverse plant species. FWT systems were meticulously designed with three plant combinations, utilizing soil and coco peat as growth media. Different FWT systems exhibited variations in their ability to remove several key water quality indicators. These variations were influenced by operational conditions, system design, plant selection, and growth media. Notably, the peat-based FWT system (FWT-BPCV) combining Canna indica and Chrysopogon zizanioides consistently demonstrated outstanding performance in reducing various pollutants, including total nitrogen (78.9 %), ammonia (90.2 %), total phosphorus (86.9 %), COD (92.8 %), BOD5 (94.8 %), TDS (70.7 %), TSS (93.6 %), turbidity (93.3 %), phosphate (73.2 %), electrical conductivity (62.5 %), and E. coli (78 %). This research suggests that FWT-BPCV is an eco-friendly wastewater treatment solution and an effective option for domestic wastewater treatment practices.

From E-Waste to High-Value Materials: Sustainable Synthesis of Metal, Metal Oxide, and MOF Nanoparticles from Waste Printed Circuit Boards.

The exponential growth of electronic waste (e-waste) has raised significant environmental concerns, with projections indicating a surge to 74.7 million metric tons of e-waste generated by 2030. Waste printed circuit boards (WPCBs), constituting approximately 10% of all e-waste, are particularly intriguing due to their high content of valuable metals and rare earth elements. However, the presence of hazardous elements necessitates sustainable recycling strategies. This review explores innovative approaches to sustainable metal nanoparticle synthesis from WPCBs. Efficient metal recovery from WPCBs begins with disassembly and the utilization of advanced equipment for optimal separation. Various pretreatment techniques, including selective leaching and magnetic separation, enhance metal recovery efficiency. Green recovery systems such as biohydrometallurgy offer eco-friendly alternatives, with high selectivity. Converting metal ions into nanoparticles involves concentration and transformation methods like chemical precipitation, electrowinning, and dialysis. These methods are vital for transforming recovered metal ions into valuable nanoparticles, promoting sustainable resource utilization and eco-friendly e-waste recycling. Sustainable green synthesis methods utilizing natural sources, including microorganisms and plants, are discussed, with a focus on their applications in producing well-defined nanoparticles. Nanoparticles derived from WPCBs find valuable applications in drug delivery, microelectronics, antimicrobial materials, environmental remediation, diagnostics, catalysis, agriculture, etc. They contribute to eco-friendly wastewater treatment, photocatalysis, protective coatings, and biomedicine. The important implications of this review lie in its identification of sustainable metal nanoparticle synthesis from WPCBs as a pivotal solution to e-waste environmental concerns, paving the way for eco-friendly recycling practices and the supply of valuable materials for diverse industrial applications.

Removal of major nutrients by sono-direct and sono-alternate current electrocoagulation process from domestic wastewater

Background: Electrocoagulation is becoming a promising eco-friendly wastewater treatment technique. It is a low-cost wastewater treatment method suitably applied for various wastewater effluent characteristics. Nevertheless, there are different kinds of electrocoagulation; comparison among them in terms of nutrient removal is investigated in the present research. This study analyzed nitrate (NO3 - ) and phosphate (PO4 3-) removal potential of the sono-alternative and direct-current electrocoagulation process. Methods: Batch reactor and sono-direct current (SDC)/sono-alternative current (SAC) electrocoagulation cell were employed to investigate NO3 - and PO4 3- removal efficiency from domestic effluents. The data gathered from laboratory experiments were analyzed using response surface methodology (RSM). ANOVA was used to examine the interaction effects of diverse parameters in terms of NO3 _ and PO4 3- removal from domestic wastewater effluents. Results: At extreme experimental conditions, the percentage of NO3 - and PO4 3- removal attained with sono-direct current electrocoagulation (SDCE) and sono-alternative current electrocoagulation (SACE) were 96.5%, 96.2% and 96.8%, 96.5, respectively. The SACE was more successful in eliminating NO3 - and PO4 3- than the SDCE process. The appearance of resistant oxide coating on the cathode and the appearance of corrosion on the anode due to oxidation processes in the case of SDCE were identified as principal factors highly affecting NO3 - and PO4 3- removal efficiency. Conclusion: With optimum process efficiency, experimental findings show that the SACE process is more capable of NO3 - and PO4 3- removal than the SDCE process.

Harnessing the potential of microalgae-bacteria interaction for eco-friendly wastewater treatment: A review on new strategies involving machine learning and artificial intelligence

In the pursuit of effective wastewater treatment and biomass generation, the symbiotic relationship between microalgae and bacteria emerges as a promising avenue. This analysis delves into recent advancements concerning the utilization of microalgae-bacteria consortia for wastewater treatment and biomass production. It examines multiple facets of this symbiosis, encompassing the judicious selection of suitable strains, optimal culture conditions, appropriate media, and operational parameters. Moreover, the exploration extends to contrasting closed and open bioreactor systems for fostering microalgae-bacteria consortia, elucidating the inherent merits and constraints of each methodology. Notably, the untapped potential of co-cultivation with diverse microorganisms, including yeast, fungi, and various microalgae species, to augment biomass output. In this context, artificial intelligence (AI) and machine learning (ML) stand out as transformative catalysts. By addressing intricate challenges in wastewater treatment and microalgae-bacteria symbiosis, AI and ML foster innovative technological solutions. These cutting-edge technologies play a pivotal role in optimizing wastewater treatment processes, enhancing biomass yield, and facilitating real-time monitoring. The synergistic integration of AI and ML instills a novel dimension, propelling the fields towards sustainable solutions. As AI and ML become integral tools in wastewater treatment and symbiotic microorganism cultivation, novel strategies emerge that harness their potential to overcome intricate challenges and revolutionize the domain.

Preparation and Modification of Activated Carbon for the Removal of Pharmaceutical Compounds via Adsorption and Photodegradation Processes: A Comparative Study

In the present research, the removal of pharmaceutical contaminants based on atenolol (AT) and propranolol (PR) using modified activated carbon (AC) in a liquid solution was studied. Two methods, adsorption and photodegradation, were used to eliminate AT and PR. First, AC was prepared from date stems and then modified via hydroxylation (AC-OH) and impregnated into titanium dioxide (AC-TiO2) separately. The removal of AT and PR was investigated in terms of experimental parameters, such as pH, concentration, temperature, and the effectiveness of the processes. The results show that the removal of AT and PR reached 92% for the adsorption method, while 94% was registered for the photodegradation process. Likewise, in optimal experimental conditions, the adsorption of AT and PR over AC-OH showed good stability and recyclability, achieving five cycles without a visible decrease in the removal capacity. The results obtained in this work suggest that the low-cost and environmentally friendly synthesis of AC-OH is suitable to be considered for wastewater treatment at the industrial scale. Interestingly, the above results open a potential pathway to determine whether adsorption or photodegradation is more suitable for eliminating wastewater-related pharmaceutical pollutants. Accordingly, the experimental results recommend adsorption as a promising, durable, eco-friendly wastewater treatment method.

Thermodynamics, kinetics and isothermal studies of tartrazine adsorption onto microcline/MWCNTs nanocomposite and the regeneration potentials

The quest for a cheap, effective, and eco-friendly wastewater treatment technique that is free of secondary toxic byproducts, calls for the fabrication of a nature-friendly adsorbent with a robust capacity to decontaminate polluted water sources and be recycled. To this end, we report the fabrication of novel nanocomposite (KMCM) from microcline (KMC) and multiwall carbon nanotubes (MWCNTs). The adsorbents (KMC and KMCM) were characterized using XRD, BET, SEM, TGA and FTIR. The novel and low-cost nano sorbent were designed for the elimination of tartrazine (Tatz) from wastewater. The adsorption of Tatz onto KMC and KMCM was influenced by adsorbent dose, initial Tatz concentration, contact time and solution pH. Experimental data acquired from the equilibrium studies were well addressed by the Langmuir isotherm model. The maximum uptake capacity of 37.96 mg g−1 and 67.17 mg g−1 were estimated for KMC and KMCM. The kinetics for the adsorption of Tatz onto KMC and KMCM was best expressed by pseudo-second-order and Elovich models. The thermodynamic parameters revealed that the uptake of Tatz onto KMC and KMCM was an endothermic (ΔH: KMC = 35.0 kJ mol−1 and KMCM = 42.91 kJ mol−1), entropy-driven (ΔS: KMC = 177.6 J K−1 mol−1 and KMCM = 214.2 J K−1 mol−1) and spontaneous process. Meanwhile, KMCM demonstrated good reusability potential and superior adsorption efficiency when compared to other adsorbents.

Cathodic biofouling control by microbial separators in air-breathing microbial fuel cells

Microbial fuel cells (MFCs) incorporating air-breathing cathodes have emerged as a promising eco-friendly wastewater treatment technology capable of operating on an energy-free basis. However, the inevitable biofouling of these devices rapidly decreases cathodic catalytic activity and also reduces the stability of MFCs during long-term operation. The present work developed a novel microbial separator for use in air-breathing MFCs that protects cathodic catalytic activity. In these modified devices, microbes preferentially grow on the microbial separator rather than the cathodic surface such that biofouling is prevented. Trials showed that this concept provided low charge transfer and mass diffusion resistance values during the cathodic oxygen reduction reaction of 4.6 ± 1.3 and 17.3 ± 6.8 Ω, respectively, after prolonged operation. The maximum power density was found to be stable at 1.06 ± 0.07 W m−2 throughout a long-term test and the chemical oxygen demand removal efficiency was increased to 92% compared with a value of 83% for MFCs exhibiting serious biofouling. In addition, a cathode combined with a microbial separator demonstrated less cross-cathode diffusion of oxygen to the anolyte. This effect indirectly induced the growth of electroactive bacteria and produced higher currents in air-breathing MFCs. Most importantly, the present microbial separator concept enhances both the lifespan and economics of air-breathing MFCs by removing the need to replace or regenerate the cathode during long-term operation. These results indicate that the installation of a microbial separator is an effective means of stabilizing power generation and ensuring the cost-effective performance of air-breathing MFCs intended for future industrial applications.

Phytoremediative adsorption methodologies to decontaminate water from dyes and organic pollutants.

Persistent organic pollutants and dyes cause major problems during ecofriendly wastewater treatment. To overcome this huge problem, several techniques have been considered and in practice for the safe disposal of organic pollutants in recent years; some of them are discussed and compared herein. This review focuses on new trends for wastewater treatment and compares them with certain other techniques alongside their pros and cons; adsorption is considered the safest among them. Adsorbents derived from agri-wastes have good capacity for the removal of these contaminants owing to their great sorption capacity, high reusability, easy operation, etc. Sometimes they need some modifications for the removal of dyes, which are also discussed in this review. This capacity of adsorbents to chelate dye molecules can be affected by factors, such as pH, the concentration of dyes and adsorbents, and temperature of the system. pH has direct influence on the ionization potential and charge on the outer surface of adsorbents. The findings on isotherms, kinetics, and desorption of plant waste-based biomaterials that are safe for the ecosystem and user friendly and are used for hazardous contaminant removal from water are summarized in this review. Finally, conclusions and future perspectives are presented, and some other materials, such as CNTs and MOFs, are also discussed as efficient adsorbents for eliminating dyes from wastewater. Finally, it is predicted that the adsorption of dyes is a more feasible solution for this dye pollution problem.

Azolla microphylla extract ZnO nanoparticles and antibacterial activity: eco-friendly wastewater treatment

Azolla microphylla extract ZnO nanoparticles and antibacterial activity: eco-friendly wastewater treatment

TiO2 Nanoparticle-Loaded Poly(NIPA-co-NMA) Fiber Web for the Adsorption and Photocatalytic Degradation of 4-Isopropylphenol.

A TiO2 nanoparticle-loaded polymer fiber web was developed as a functional material with the ability to adsorb and photo-catalytically degrade organic pollutants in aquatic media. A linear copolymer of N-isopropylacrylamide (primary component) and N-methylol acrylamide (poly(NIPA-co-NMA)) was prepared, and composite fibers were fabricated by electrospinning a methanol suspension containing the copolymer and commercially available TiO2 nanoparticles. The crosslinking of the polymer via the formation of methylene bridges between NMA units was accomplished by heating, and the fiber morphology was analyzed by electron microscopy. 4-Isopropylphenol generated by the degradation of bisphenol A—one of the endocrine-disrupting chemicals—was used as the model organic pollutant. As poly(NIPA) is a thermosensitive polymer that undergoes hydrophilic/hydrophobic transition in water, the temperature-dependence of the adsorption and photocatalytic degradation of 4-isopropylphenol was investigated. The degradation rate was analyzed using a pseudo-first-order kinetic model to obtain the apparent reaction rate constant, kapp. The enhancement of the photocatalytic degradation rate owing to the adsorption of 4-isopropylphenol onto thermosensitive poly(NIPA)-based fibers is discussed in terms of the ratio of the kapp of the composite fiber to that of unsupported TiO2 nanoparticles. Based on the results, an eco-friendly wastewater treatment process involving periodically alternated adsorption and photocatalytic degradation is proposed.

Advances in the development of electrode materials for improving the reactor kinetics in microbial fuel cells

Microbial fuel cells (MFCs) are an emerging technology for converting organic waste into electricity, thus providing potential solution to energy crises along with eco-friendly wastewater treatment. The electrode properties and biocatalysts are the major factors affecting electricity production in MFC. The electrons generated during microbial metabolism are captured by the anode and transferred towards the cathode via an external circuit, causing the flow of electricity. This flow of electrons is greatly influenced by the electrode properties and thus, much effort has been made towards electrode modification to improve the MFC performance. Different semiconductors, nanostructured metal oxides and their composite materials have been used to modify the anode as they possess high specific surface area, good biocompatibility, chemical stability and conductive properties. The cathode materials have also been modified using metals like platinum and nano-composites for increasing the redox potential, electrical conductivity and surface area. Therefore, this paper reviews the recent developments in the modification of electrodes towards improving the power generation capacity of MFCs.

Removal of nutrients from domestic wastewater using constructed wetlands: assessment of suitable environmental and operational conditions

Constructed wetlands (CWs) offer an eco-friendly wastewater treatment technology primarily for decentralized locations. They support a dense growth of macrophytes which help in the reduction of water velocity, development of conducive microenvironments and provide adherence sites for microorganisms to develop biofilms. Several environmental and operational parameters are crucial for the efficient working of CWs wherein, suitable pH, temperature and dissolved oxygen (DO) are more significant. The performance of CWs has been enhanced significantly through effluent recirculation and artificial aeration. Removal of phosphorus proceeds via adsorption within media material, sedimentation, cation exchange, precipitation and uptake by macrophytes and the removal of nitrogen occurs mainly by microbial communities and macrophytic uptake. In colder climates, the bioaugmentation of microbial communities is required to increase the treatment efficiency. Various previous research findings showed several aspects of CWs that could potentially affect removal efficiency of the nutrients from the wastewater. However, maintaining suitable environmental and operational conditions for the effective operation of CWs remains a challenge. Therefore, the objectives of this review-based study are to provide the most favorable environmental conditions for the effective operation of CWs. Recent developments in operational and working parameters of CWs focusing on the selection of macrophytes and substrate material, carbon source, feeding mode, hydraulic loading rates and retention times are discussed. The study also provides effect of effluent recirculation, bioaugmentation of microbes, suitable C/N ratio and artificial aeration for the domestic wastewater treatment.

Chitosan-polyglycidol complexes to coating iron oxide particles for dye adsorption

The study sheds light on the interaction between chitosan (Ch) and polyglycidol (PGL) and uses their interpolymer complex in hydrophilic coating of iron oxide particles (M). Preliminary investigations were performed by modeling chitosan and polyglycidol chains interactions using coarse grained beads approximation and molecular dynamics simulations. The results revealed that Ch and PGL chains associate together forming weak strength complexes, which was experimentally confirmed by surface tension, fluorescence and FTIR. The Ch-PGL mixture (C) and sodium dodecylsulfate (S) were used for layer-by-layer preparation of hydrophilic multilayer coatings of M. The successful covering, demonstrated by DLS, Zeta potential, FTIR, EDAX, preserved the particles super-paramagnetic properties. The most stable multilayer nanocomposite (MSCS) efficiently adsorbed methylene blue from water. The Freundlich model fitted well the equilibrium isotherm data, indicating a heterogeneous, multilayer adsorption. Benefiting from both nano-size and magnetic properties, this adsorbent could be an effectively, cheaply and eco-friendly wastewater treatment means.

Agar extraction and purification of R-phycoerythrin from Gracilaria tenuistipitata, and subsequent wastewater treatment by Ulva prolifera

This study investigated the large-scale use of the red macroalga Gracilaria tenuistipitata to extract partially purified R-phycoerythrin in combination with the sequential extraction of agar. The main objective was to investigate the purification of R-PE, the extraction of agar and treatment of wastewater from the whole extraction process using the green macroalga Ulva prolifera. Results showed that the processing of 1 kg fresh biomass of G. tenuistipitata yielded a 30.34 μg/g R-phycoerythrin (purification ratio > 4) with 13.83% extraction efficiency. Initial phycobiliprotein extraction had no effect on the agar yield. The physicochemical properties of the agar had industrial applications. This method of extraction reduced the water volume and alkali requirement compared with that from direct extraction from algae. In addition, the removal rates (mean ± standard deviation) from wastewater of BOD, COD, total nitrogen, inorganic nitrogen, ammonia nitrogen, nitrate, nitrite, total phosphorus and inorganic phosphorus were 28.34 ± 0.10%, 23.50 ± 3.47%, 45.59 ± 6.31%, 63.82 ± 2.94%, 40.77 ± 0.95%, 74.06 ± 5.63%, 70.37 ± 2.59%, 65.26 ± 5.77%, and 72.40 ± 5.43% after the treatment with 2 days respectively. This extraction and subsequently eco-friendly wastewater treatment method could have practical application in the agar industry.

Assessment of algal biomasses having different cell structures for biosorption properties of acid red P-2BX dye

The increased applications of synthetic dyes in the textile industrial activities have negative implications such as water pollution by dye containing effluents. The treatment of industrial wastewater is important due to the toxic effects of dyes. Biosorption is defined as a relatively economical and eco-friendly wastewater treatment method. The aim of this study was to examine the biosorption of Acid Red P-2BX (ARP-2BX) dye that is extensively used and abundantly found in textile wastewater. The dye biosorption capacities of prokaryotic algae (Phormidium animale) and eukaryotic algae (Scenedesmus sp.) were investigated. The effects of pH (2–10), biosorbent type (ash or dried), initial dye concentration, biosorbent dosage, contact time and temperature were determined. Maximum dye removal was performed by dried P. animale as 99.70 ± 0.27%. The biosorption isotherms and kinetics were also calculated, the ARP-2BX dye biosorption was fitted with Langmuir isotherm and pseudo-second-order kinetic models. In order to analyze the changes that occurred in algal structure, FTIR and elemental analysis were done. The results of this study concluded that P. animale was a favorable biosorbent for treatment of textile wastewater.