Removal of chemical oxygen demand from textile wastewater using a natural coagulant

Natural-based coagulants/flocculants as sustainable market-valued products for industrial wastewater treatment: a review of recent developments

Industrial wastewater is categorized as a voracious consumer of fresh water and a high-strength source of pollution. Coagulation-flocculation is a simple and cost-effective technique for removing organic/inorganic compounds and colloidal particles from industrial effluents. Despite the outstanding natural properties, biodegradability, and efficacy of natural coagulants/flocculants (NC/Fs) in industrial wastewater treatment, their significant potential to remediate such effluents is underappreciated, particularly in commercial scale applications. Most reviews on NC/Fs focused on the possible application of plant-based sources such as plant seeds, tannin, certain vegetables/fruit peels, and their lab-scale potential. Our review expands the scope by examining the feasibility of using natural materials from other sources for industrial effluent decontamination. By analyzing the latest data on NC/Fs, we identify the most promising preparation techniques for making these materials stable enough to compete with traditional options in the marketplace. An interesting presentation of the results of various recent studies has also been highlighted and discussed. Additionally, we highlight the recent success of using magnetic-natural coagulants/flocculants (M-NC/Fs) in treating diverse industrial effluents, and discuss the potential for reprocessing spent materials as a renewable resource. The review also offers different concepts for suggested large-scale treatment systems used by MN-CFs.

Impact of textile dyes on health and ecosystem: a review of structure, causes, and potential solutions

The rapid growth of population and industrialization have intensified the problem of water pollution globally. To meet the challenge of industrialization, the use of synthetic dyes in the textile industry, dyeing and printing industry, tannery and paint industry, paper and pulp industry, cosmetic and food industry, dye manufacturing industry, and pharmaceutical industry has increased exponentially. Among these industries, the textile industry is prominent for the water pollution due to the hefty consumption of water and discharge of coloring materials in the effluent. The discharge of this effluent into the aquatic reservoir affects its biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), and pH. The release of the effluents without any remedial treatment will generate a gigantic peril to the aquatic ecosystem and human health. The ecological-friendly treatment of the dye-containing wastewater to minimize the detrimental effect on human health and the environment is the need of the hour. The purpose of this review is to evaluate the catastrophic effects of textile dyes on human health and the environment. This review provides a comprehensive insight into the dyes and chemicals used in the textile industry, focusing on the typical treatment processes for their removal from industrial wastewaters, including chemical, biological, physical, and hybrid techniques.

Exploring the extraction methods for plant-based coagulants and their future approaches

The application of plant-based coagulants in wastewater treatment has increasingly progressed in the coagulation-flocculation process toward green economy and cleaner production. Plant-based coagulants have a potential as essential substitutes for commercially used chemical coagulants because of their natural characteristics and biodegradability. Chemical coagulants leave residues in treated water and generated sludge, which cause harm to human health and the ecosystem. Thus, the exploration of plant-based coagulants in wastewater treatment could reduce and eliminate the potential damage of chemical coagulants and promote the alternative approach for sustainable environment. The general processing steps of the end-to-end plant-based coagulant production, which includes primary, secondary, and tertiary stages, are discussed. However, this review focuses more on the extraction process using different solutions and compares the performance of different coagulants in removal activities after effluent treatment. Discussion on the arising challenges is elaborated, and approaches for plant-based coagulant research in the near future are suggested.

Mucilage Extracted from Dragon Fruit Peel (Hylocereus undatus) as Flocculant for Treatment of Dye Wastewater by Coagulation and Flocculation Process

Dye wastewater from textile industries shows very low biodegradability due to high molecular weight and complex structures of dyes. So far, the most simple method for treatment of this type of wastewater has been coagulation and flocculation. This study determined the removal of turbidity and other pollutants from dye wastewater by mucilage extracted from the peel of dragon fruit (Hylocereus undatus) and its effect in reducing synthetic chemical polyaluminum chloride (PACl) used in coagulation and flocculation (CF) process. The removal of turbidity in a sequent CF process using PACl and dragon fruit mucilage was investigated based on Jar tests. Maximum coagulation efficiencies of PACl were typically observed at pH 4.0-6.0 and PACl concentrations of about 100-150 mg/L depending on types of wastewater, whereas optimal settling times were 30-60 minutes, respectively. The addition of dragon fruit mucilage (0.5-50 mg/L) after PACl (75-245 mg/L) resulted in turbidity removal efficiencies up to 95%. The addition of mucilage extracted from dragon fruit peels was proven to increase turbidity removal efficiency and decrease PACl use. The increase of turbidity removal was often estimated at 10-32%, whereas PACl used was about 3-10% less compared to total PACl needed for obtaining comparable efficiency when used alone. The flocculation activity of mucilage was also compared to polyacrylamide (PAM)—a synthetically organic flocculant. Since the peel of a dragon fruit is an abundant agriculture waste in Vietnam, using its extracted mucilage as a flocculant is an environmentally friendly method.

Aloe sp. leaf gel and water glass for municipal wastewater sludge treatment and odour removal

Aloe gel (Alg), which is a natural extract from the Aloe sp. plant, was evaluated in this study for its potential use as a bioflocculant to treat urban wastewater sewage sludge. The gel was used alone and combined with water glass (WG) under controlled conditions in laboratory experiments. Alg was found effective to settle the flocculated sludge rapidly and remove distinctive unpleasant odours of the sludge as highlighted by gas chromatography-mass spectrometry (GC/MS) analysis. Furthermore, Alg was pH tolerant and had no effect in changing the pH of the wastewater. The optimum dose of Alg was 3% at which a sludge volume index (SVI) of 45.4 mL/g was obtained within 30 min settling time. To enhance the treatment performances of Alg, WG was also evaluated as an alkali agent to further reduce the chemical oxygen demand (COD) and ammonia (NH₄-N) in the wastewater. At equal doses of 3% of WG and Alg each, the combined treatment outcomes showed high turbidity and NH₄-N removals of 83 and 89%, respectively, but the overall COD removal was at best 25%. The settling rate of treated sludge with combined Alg/WG was very rapid giving an SVI of 25.4 mL/g within only 5 min.

Data on the removal of turbidity from aqueous solutions using polyaluminum chloride

Polyaluminum chloride (PAC) is claimed to be superior to conventional coagulants because of higher removal of particulate and/or organic matters as well as inherent advantages of lower alkalinity consumption and lesser sludge production. 1000 mL of the reaction mixture was examined using parameters, including PAC dose (5–10 mg/L), pH (4–9), and turbidity (1.9 NTU). The content was stirred at 120 rpm for 1 min. Thereafter, the turbidity of water samples was measured using a P2100 turbidimeter. Data indicated that the maximum removal efficiency of turbidity (97.74%) obtained under the PAC doses of 4 and 10, and the pH of 8. There is not a significant relationship between the different dosages of PAC (P-value > 0.05), but the influence of pH on the removal of turbidity was significant (P-value < 0.05). Based on the dataset, the removal efficiency of turbidity was depended on PAC and pH.

Dataset on comparing the corrosion indices of alum and ferric chloride coagulants with phosphate dose elevation

The aim of this data was to assess and compare the corrosion indices of alum and ferric chloride coagulants in conventional coagulation process of water with elevation of phosphate dose. After preparing synthetic water samples, jar experiments were performed with elevation of different phosphate doses using alum and ferric chloride coagulants. Then, corrosion indices of Ryznar and Langelier of water samples were calculated. The results indicated that the values of Ryznar and Langelier index in the experimental samples were 7 and less than zero, and the water conditions were under saturated. The corrosion and precipitation indices indicated that the water samples can be considered as corrosive waters.

Experimental data on the adsorption of Reactive Red 198 from aqueous solution using Fe3O4 nanoparticles: Optimization by response surface methodology with central composite design

The aim of this study was to evaluate the efficiency of Fe₃O₄ nanoparticles for Reactive Red 198 adsorption. The adsorbents were characterized by SEM and XRD. In this dataset, the influence of Reactive Red 198 dye concentration, solution pH, adsorbent dosage, and contact time on Reactive Red 198 dye adsorption by Fe₃O₄ nanoparticles was tested by central composite design (CCD) under response surface methodology (RSM). The Fe₃O₄ nanoparticles adsorbent was prepared by chemical co-precipitation. The process efficiency was achieved in optimal conditions including pH=7, adsorbent dosage equal to 0.5 g/L, initial dye concentration of 100 mg/L, contact time equal to 30 min, 88%. Overall, the data offer a facile adsorbent to remove Reactive Red 198 dye from aqueous solutions.

Delaminated montmorillonite with iron(III)-TiO₂ species as a photocatalyst for removal of a textile azo-dye from aqueous solution

A set of mesoporous delaminated montmorillonites containing iron(III)-titanium oxide species was synthesized using two minerals: a bentonite as support and an ilmenite as source of Fe-TiO2 species. Several values of both sulphuric acid concentration and temperature were employed to extract Fe-TiO2 species from an ilmenite. Analyses by X-ray fluorescence, X-ray diffraction, scanning electron microscopy and nitrogen adsorption-desorption confirmed the successful formation of delaminated (or exfoliated) mesoporous structures. Optical properties of solids were determined by UV-Vis diffuse reflectance spectroscopy, and their band gap energy values were also calculated. A small UV-shift of band gap values regarding that of commercial photo-active TiO2 was detected as consequence of the quantum size effect, suggesting that photocatalytic experiments should be performed under UV-radiation assistance. The synthesized solids showed good activity in the photocatalytic oxidation of a textile dye (reactive yellow 145: RY 145), achieving conversions higher than 70% and chemical oxygen demand removal between 60% and 80%.

A novel method for extraction of a proteinous coagulant from Plantago ovata seeds for water treatment purposes

Several chemicals have been applied in the process of coagulant extraction from herbal seeds, and the best extraction has been obtained in the presence of KCl or NaNO₃[1], [2], [3], and NaCl [4]. However, the main challenge posed to these methods of coagulant extraction is their relatively low efficiency for water treatment purposes and the formation of dissolved organic matter during the treatment process. In these methods the salts, which have a one-valance metal (Na⁺ and K⁺), are deposited in the internal structure and the pore of the coagulant, and may be useful for the coagulation/flocculation process. In this research, we found that modified methods produced more dense protein. Therefore, the modified procedure was better than the older one for removal of turbidity and harness from the contaminated water. Here we describe a method where:

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According to the Hardy–Schulze rule, we applied the Fe³⁺ ions instead of Na⁺ and K⁺ for the extraction of protein from Plantago ovata seeds.

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The method was narrowed to extract protein by ethanol (defatting) and ammonium acetate and CM-Sepharose (protein extraction).

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Two consecutive elutriations of crude extract was directly performed using 0.025-M FeCl₃ and 0.05-M FeCl₃ according to the basis of the ion-exchange processes.

Detoxification and color removal of Congo red by a novel Dietzia sp. (DTS26) - a microcosm approach

The present study deals with the decolorization and detoxification of Congo red (CR) by a novel marine bacterium Dietzia sp. (DTS26) isolated from Divar Island, Goa, India. The maximum decolorization of 94.5% (100 mg L(-1)) was observed under static condition within 30 h at pH 8 and temperature 32±2°C. Bacterially treated samples could enhance the light intensity by 38% and the primary production levels 5 times higher than the untreated. The strain was also able to reduce COD by 86.4% within 30 h at 100 mg L(-1) of CR dye. The degraded metabolites of CR dye were analyzed by FTIR, HPLC, GC-MS and the end product closely matches with 4-amino-3-naphthol-1-sulfonate which is comparatively less toxic than CR. Bioassay experiments conducted in treated samples for Artemia franciscana showed better survival rates (after 72 h) at higher concentration of CR (500 mg L(-1)). This work suggests the potential application of DTS26 in bioremediation of dye wastes and its safe disposal into coastal environment.