Aluminum Sulfate Research Articles

Life Cycle Assessment of a Vegetable Tannin-Based Agent Production for Waters Treatment

The scarcity of natural resources makes it essential to develop products that meet environmental requirements. This is also true for the water and wastewater treatment business, where even consolidated processes, such as coagulation and flocculation, must be improved, opening opportunities for searching for alternative options to conventional processes. Among the existing options, tannin-based agents (TBAs) have been highlighted in recent years due to their biodegradability and proven efficiency. However, little is known about the impacts of the production process of these agents on an operational/industrial scale. In this study, an examination of the environmental impacts of the full-scale production (more than 500 tons yearly) of a TBA from Acacia spp. (known as black acacia or mimosa) was carried out. To accomplish this, a life cycle assessment (LCA) was developed using openLCA version 2.0.0 to assess a cradle-to-gate system of 1 kg of packed TBA produced. Additionally, a comparison was made between the impacts of the production of TBA and a conventional water treatment agent, aluminum sulfate, to verify the benefits of producing the former. The most relevant impacts resulting from the production of 1 kg of TBA are observed in the following categories: global warming (1.52 kgCO2-eq); terrestrial (7.67 kg1.4-DCB-eq), freshwater (0.06 kg1.4-DCB-eq), and marine (0.08 kg1.4-DCB-eq) ecotoxicities; carcinogenic (0.10 kg1.4-DCB-eq) and non-carcinogenic (1.36 kg1.4-DCB-eq) human toxicities; and water use (0.02 m3). The main contributors to the impacts were the chemicals ammonium chloride and formaldehyde used, the transport of inputs, and the energy used. The aluminum sulfate showed better performance than the TBA for a greater number of categories; however, the normalization of the impacts showed the TBA as a very interesting option. The results obtained here can be used by TBA producers to act on the most impactful categories so that the production process becomes increasingly sustainable.

Utilisation of Waste Sludge from Drinking Water Treatment as a Filler Material in Hot Mix Asphalt.

This research investigated the suitability of using sludge from the treatment of drinking water in hot mix asphalt (HMA) as a filler material. The storage and environmental impact of sludge is an enormous problem, especially for countries with large populations. Two different types of sludges, ferric chloride (FC) and aluminium sulphate (AS), were used as a filler material in HMA. The Hamburg Wheel Tracking (HWT) test, which correlates with rutting, and the Indirect Tensile Strength (ITS) test, which indicates the moisture sensitivity of HMA, were carried out at the optimum bitumen content of the mixes to investigate the usability of sludge in HMA. The test results indicate the usability of FC and AS in HMA compared to the reference mixes. However, the AS type of sludge has better rutting resistance than the FC type. Although the results support the usability of both sludges in HMA, it should be noted that the increased cost of the mix containing sludges due to the combustion process and the increased bitumen content during application should be considered.

Organic-inorganic core-shell materials as reinforced fillers of UHMWPE to improve its tribological and mechanical properties

Generally, modification of materials by adding multiple types of nano particles could cause dispersion problems, generally limited the performance improvement effect. Herein, we report the modification of UHMWPE materials by organic-inorganic core-shell particles with PTFE as the core and Al(OH)3 as the shell, which prepared by in-situ polymerization of sodium bicarbonate and aluminum sulfate solution. Core-shell particles were filled in UHMWPE matrix and sintered into composite by spark plasma sintering (SPS). The mechanical and tribological properties of the composites were characterized by tensile compression testing machine, universal micro tribometer (UMT-5), three-dimensional white light interferometer and scanning electron microscope (SEM). The results showed that the addition of core-shell structural materials effectively improved the tribological properties (friction coefficient decreased by 40%, wear rate decreased by 30%) and mechanical properties (compression strength increased by 2.4 times) of the composites. It was demonstrated that the inorganic framework provided strength to improve the mechanical properties and wear resistance of materials, and the organic phase was used as a lubricating phase to reduce the friction coefficient of materials. Surface treatment of core-shell particles both improved the binding between particles and matrix and decreased the formation of agglomerations, thus significantly reducing ploughing phenomena’s effect produced by abrasive wear of agglomeration

Recovery of aluminum oxide and iron oxide from aluminum electrolysis iron-rich cover material and preparation of aluminum fluoride.

In aluminum electrolysis, the iron-rich cover material is formed on the cover material and the steel rod connecting the carbon anode. Due to the high iron content in the iron-rich cover material, it differs from traditional cover material and thus requires harmless recycling and treatment. A process was proposed and used in this study to recovery F, Al, and Fe elements from the iron-rich cover material. This process involved aluminum sulfate solution leaching for fluorine recovery and alkali-acid synergistic leaching for α-Al2O3 and Fe2O3 recovery were obtained. The optimal leaching rates for F, Na, Ca, Fe, and Si were 93.92, 96.25, 94.53, 4.48, and 28.87%, respectively. The leaching solution and leaching residue were obtained. The leaching solution was neutralized to obtain the aluminum hydroxide fluoride hydrate (AHFH, AlF1.5(OH)1.5·(H2O)0.375). AHFH was calcined to form a mixture of AlF3 and Al2O3 with a purity of 96.14%. The overall recovery rate of F in the entire process was 92.36%. Additionally, the leaching residue was sequentially leached with alkali and acid to obtain the acid leach residue α-Al2O3. The pH of the acid-leached solution was adjusted to produce a black-brown precipitate, which was converted to Fe2O3 under a high-temperature calcination, and the recovery rate of Fe in the whole process was 94.54%. Therefore, this study provides a new method for recovering F, Al, and Fe in iron-rich cover material, enabling the utilization of aluminum hazardous waste sources.

Development of green and sustainable ammonia sensor from xanthohumol extract-immobilized polylactic acid nanofibers

Ammonia is a significant industrial gaseous agent that is colorless. However, long exposure to ammonia gas can cause organ damages or even death. This study describes the preparation of a solid-state vapochromic sensor for gaseous and aqueous ammonia using eco-friendly smart colorimetric polylactic acid nanofibers. Xanthohumol (XMOL) is a natural spectroscopic probe that can be found in the common hop (Humulus lupulus L.) plant. Nanoparticles of mordant/xanthohumol (M/XMOL) coordinated complex were synthesized by immobilizing the xanthohumol direct dyestuff into polylactic acid nanofibers in the presence of a mordant (potassium aluminum sulfate). Xanthohumol can be described as an appropriate sensor for gaseous and aqueous ammonia due to its tiny molecular size and high water-solubility. Both of CIE Lab color parameters and absorbance spectra were used to inspect the color shift of the xanthohumol-finished polylactic acid nanofibers from yellow to colorless upon exposure to ammonia. This could be attributed to the intramolecular charge transfer caused by molecular switching of xanthohumol. In a fraction of second, the polylactic acid nanofibrous fabric showed a colorimetric change with a detection limit of 10–450 mg/L. The absorption spectra of the xanthohumol probe exhibited hypsochromic shift with a wavelength change from 465 nm to 315 nm (isosbestic point of 370 nm) in response to an aqueous solution of ammonia. Transmission electron microscopic (TEM) images showed that M/XMOL particles were 13–27 nm in diameter, whereas scanning electron microscopic (TEM) images demonstrated that the polylactic acid nanofibers were 150–450 nm in diameter. We observed no significant differences in air-permeability and bending-length of the nanofibrous fabric after immobilization of M/XMOL into polylactic acid nanofibers. In addition, the colorfastness properties of the treated polylactic acid nanofibers were investigated.

Mechanistic Study of the Influence of Reactant Type and Addition Sequence on the Microscopic Morphology of α-Al2O3

To perform an in-depth study of the crystal growth habits and phase changes of alumina and its precursors in reaction systems, this paper studied the effects of reactant type and addition order on the morphology of alumina using hydrothermal methods with different precipitants and aluminum sources as reactants. Research has shown that sodium bicarbonate and ammonium bicarbonate can be used as precipitants to prepare adhered spherical alumina and irregular short rod alumina, while potassium bicarbonate can be used as a precipitant to prepare hexagonal flake alumina. Using aluminum sulfate octahydrate, aluminum chloride hexahydrate, and aluminum nitrate, nine hydrates were prepared as aluminum sources, and agglomerated alumina, irregular short rod-shaped alumina, and fused alumina were obtained. The order of reactant addition affects the precursor phase of alumina, thereby affecting the microstructure of alumina after calcination, resulting in flake alumina with pores and short rod alumina. The results of this paper will provide theoretical guidance for the preparation of alumina with different micromorphologies.

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.

Utilizing the Adsorbability of Pseudoboehmite for Tailoring the Stability of an Aluminum Sulfate Alkali-free Accelerator for Shotcrete.

Shotcrete is widely used in tunnels, bridges, culverts, and other large-scale projects. The accelerator is an additive employed to expedite the setting time of shotcrete. Previous research primarily concentrated on enhancing the early strength of accelerators, whereas their long-term stability has been inadequately investigated. In this study, pseudoboehmite (PB) and amorphous aluminum hydroxide (AAH) were incorporated into the accelerator to enhance its stability over a period of 90 days without any signs of crystallization or delamination. Furthermore, the accelerator exhibited an initial setting time of 170 s, a final setting time of 550 s, and a compressive strength of 11.58 MPa after 1 day. The mechanism of effects was studied by isothermal calorimetry, FTIR, XRD, TG-DTG, and SEM analysis. The enhancement in stability is attributed to the distinctive adsorption and thixotropic properties of PB, which facilitate the formation of an electrical double-layer structure in acidic solutions. The expedited setting and hardening are primarily due to the equilibrium between Al3+, SO42-, and Ca2+ ions, which accelerates the hydration process of cement. This research offers a methodology for developing a high-performance, alkali-free liquid accelerator.

Synergistic Improvement in Setting and Hardening Performance of OPC-CSA Binary Blended Cement: Combined Effect of Nano Calcium Carbonate and Aluminum Sulfate

The combined effect and corresponding mechanism of nano calcium carbonate (NC) and aluminum sulfate (AS) on the setting and hardening performance of binary blended cement (ordinary Portland cement (OPC) and calcium sulfoaluminate cement (CSA)) were evaluated through multiple experiments, including setting time, calorimetry, compressive strength, X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). The results showed that, as compared to OPC, OPC-CSA binary blended cement exhibited reduced setting time but decreased early strength, which could be caused by the depressed silicate phase hydration due to the fast supply of aluminate ions during the hydration of aluminate-contained phases contained in CSA. However, through the combined addition of NC and AS, the depressed silicate phase hydration was greatly promoted by NC due to its nucleation effect, and the reduced early strength was significantly improved. Further analysis indicates that the combined addition of NC and AS can promote the formation of C-S-H gel and decrease the porosity of the hardened OPC-CSA binary paste. In this way, one promising repair material with rapid setting and hardening properties was prepared by OPC-CSA binary blended cement with the combined addition of NC and AS.

Properties of elephant grass made particleboards: Influence of a hardener

The objective of the study was to assess the performance of one of the most abundant raw materials on Earth – the Elephant grass, for the production of particleboard bonded using cassava starch blended with Aluminium sulphate (Al2(SO4)3) as hardener. The physical, mechanical and decay properties of the manufactured particleboards were analyzed and compared with EN 312-2 (2005) and ANSI A208.1 (1999) standards for particleboards. The characterization also included thermogravimetric analysis and scanning electron micrographs. The results showed that the interaction of the Aluminium sulphate (Al2(SO4)3) hardener and the adhesives in the particleboard significantly affected the physical, mechanical, thermogravimetric and the decay properties of the manufactured particleboards. The particleboards with only Cassava starch as adhesive recorded 11.14% and 24.84% for 24-hour water absorption and thickness swelling respectively. However, with the blending of the adhesive with Al2(SO4)3, Cassava starch recorded 20.51% better for 24-hour WA and 35.62% better for 24-hour TS. Urea formaldehyde as an adhesive blended with the hardener also recorded better performance in the 24-hour dimensional stability property assessment. Similar trends of enhanced property performance were observed for the intended properties tested when Al2(SO4)3 is added to each adhesive. Static bending, hardness, internal bond strength, dimensional stability, thermogravimetric and decay resistance properties of the test particleboard improved with the addition of Al2(SO4)3.

Formulation of a cement-based grout characterizing controllable gelation time and its modification mechanism

Achieving a coordinated balance between pumpability, setting time, and compressive strength is essential for the effective implementation of grouting tasks. This facet also poses a significant challenge in the formulation of cement-based rapid-setting grout. Therefore, precise control over gelation time, while concurrently preserving the pumpability and mechanical strength of cement grout, unquestionably enhances its engineering feasibility. In pursuit of this objective, the current study executed a factorial experiment, assigning alkanolamine, fluoride, aluminum sulfate, and citric acid as experimental factors. Subsequently, through an experiment involving changes to the experimental setup, mathematical predictive models for diverse performance parameters were established to determine the optimal formula. Moreover, to elucidate the hydration process of the proposed grout, a comprehensive investigation was conducted using factor effect analysis, isothermal calorimetry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Finally, by drawing on the results of the above-mentioned experiments and theoretical analyses, the modification mechanisms of the admixtures on the performance of the matrix were deduced. This paper introduces a novel approach to optimize the overall performance of rapid-setting grout, providing a new material solution for grouting jobs.

Enhancing strength of cement using aluminium sulfate accelerator with aluminium formate

An alkali-free liquid accelerator was prepared with aluminium sulfate and aluminium formate as the main components. The effects of the accelerator on the setting of paste and the mechanical strength of mortar were studied, and the impact of the accelerator on the early hydration behaviour and hydration products of the paste were investigated by isothermal calorimeter analysis, X-ray diffraction analysis, scanning electron microscopy and thermogravimetric analysis. The results show that the accelerator is excellent for the rapid setting and hardening of the cement. When the content of the accelerator was 8 wt%, the initial setting time and final setting time of the paste were 85 s and 180 s, respectively, and the strengths of the mortar at 1 day and 28 days were 9.52 MPa and 44.42 MPa, respectively. The proposed accelerator can accelerate the dissolution and hydration of tricalcium aluminate and tricalcium silicate and promote the formation of ettringite, formate and portlandite.

USE OF COAGULANT FROM PLANT ORIGIN AS AN ALTERNATIVE IN THE TREATMENT OF EFFLUENTS FROM SANITATION INDUSTRY

The use of aluminum sulphate-based coagulants, associated with flocculants, is frequent in the treatment of effluents. However, as a by-product, chemical sludge is produced, containing aluminum salts, which pollute the environment. The present work aimed to evaluate the performance of a vegetable coagulant based on tannin in the treatment of effluent from a sanitizing industry. Three experiments were carried out, using 1.0 % w/v of aluminum sulfate and vegetable coagulant, and using 0.25 % w/v of the vegetable coagulant. According to the tests, the vegetable coagulant at 0.25 % m/v reduced 60.4 % of turbidity, 71.0 % of total phosphorus, 98.0 % of anionic surfactants and completely removed animal and vegetable oils and greases and total suspended solids, generating an aluminum-free sludge. The vegetable coagulant acted simultaneously as a coagulant and flocculant and did not require adjustment of effluent pH, not requiring the use of flocculants and alkaline agents, in addition to being effective at lower dosages in relation to the coagulant based on aluminum sulfate. Therefore, the use of vegetable coagulant is technically feasible due to its biodegradability, sludge application potential, and because it does not require special investments or major changes to the existing effluent treatment infrastructure.

Effect of Al2(SO4)3 Additive on the Properties of Calcined Gypsum Prepared from Flue Gas Desulfurization

In order to upgrade the utilization of flue gas desulfurization (FGD) gypsum, crystal modifier aluminum sulfate (Al2(SO4)3) was added into FGD gypsum to prepare calcined gypsum by calcining at normal pressure, and the effect of Al2(SO4)3 addition on the performance of calcined gypsum was studied. The results show that the addition of Al2(SO4)3 to FGD gypsum is slightly beneficial to promote the crystallization of hemihydrate gypsum (HH) along the a-axis direction. The Al2(SO4)3 addition also has a quick-setting effect on gypsum plaster during the hydration process, meanwhile inhibiting the growth of the (020) crystal plane of dihydrate gypsum (DH), then promoting uniform growth and aggregation along the c-axis. The close stacking makes hardened gypsum body dense and improves the strength of calcined gypsum. The strength of calcined gypsum prepared by calcining FGD gypsum with Al2(SO4)3 of 0.6 wt.% at 170 ℃ for 2 h is the highest. 2 h and 7 d flexural strength are 3.80 MPa and 7.20 MPa, and 2 h and 7 d compressive strength are 9.05 MPa and 19.23 MPa, respectively. In addition, 2 h flexural and compressive strength of the calcined gypsum with 0.6 ~ 1.0 wt.% of Al2(SO4)3 prepared at 170 ~ 180 ℃ for 2 h increase by 16 ~ 22 % and 20 ~ 33 %, respectively, which is very advantageous for the high value-added reuse of FGD gypsum for the preparation of high-quality calcined gypsum.

Green industry work: production of FeCl3 from iron and steel industry waste (mill scale) and its use in wastewater treatment

Mill scale (MS) is considered to be a significant metallurgical waste, but there is no economical method yet to utilize its metal content. In this study, which covers various processes in several stages, the solution of iron in MS, which is the Iron and Steel Industry (I&SI) waste, as FeCl3 (MS-FeCl3) in the thermoreactor in the presence of HCl, was investigated. In the next step, the conditions for using this solution as a coagulant in the treatment of I&SI wastewater were investigated using the jar test. The results of the treated water sample were compared by chemical oxygen demand (COD), total suspended solids (TSS), color, and turbidity analyses using commercial aluminum sulfate (Al2(SO4)3) and FeCl3 (C-FeCl3). Additionally, heavy metal analyses were conducted, and the treatment performance of three coagulants was presented. Accordingly, while 2.0 mg/L anionic polyelectrolyte was consumed at a dosage of 4.05 mg/L Al2(SO4)3 at pH 7.0, 0.25 mg/L anionic polyelectrolyte was consumed at a dosage of 1.29 mg/L at pH 5.0 in the C-FeCl3 and MS-FeCl3 studies. Also, Fe, Cr, Mn, Ni, Zn, Cd, Hg, and Pb removal efficiencies were over 93.56% for all three coagulant usage cases. The results showed that the wastewater treatment performance of MS-FeCl3 by the recycling of MS, which is an I&SI waste, was at the same level as C-FeCl3. Thus, thanks to recycling, waste scale can be used as an alternative to commercial products for green production.Graphical abstract

Research on synergistic disposal and high-value utilization of secondary aluminum dross and spent carbon anode

Significant hazardous by-products emerged from the aluminum electrolysis realm, including secondary aluminum dross (SAD) and spent carbon anodes (SCA), with an anticipated annual yield surpassing 800,000 tons. These solid wastes showcase distinct complexation properties enriched with aluminum and fluoride. In this paper, aluminum or aluminum compounds will be extracted from SAD by sulfuric acid first to prepare an aluminum sulfate solution, which could be used to extract cryolite in SCA by Al-F complexation. A second-step alkaline leaching is aimed at enhancing Al and F dissolution from the first-step leaching acid-leaching residue of SAD and SCA. Under optimal conditions, the ensuing data reveals the soluble components in SAD reaching a leaching zenith of 90.3%, with the Al2O3 faction standing tall at 91.08%. Simultaneously, SCA's F leaching efficiency hits an impressive 98.20%, hence the carbon residue enriched with a purity of 75.5%. Finally, the acid-leaching solution and alkaline-leaching solution could be mixed to prepare flexibly and controllably aluminum fluoride or cryolite by adjusting the pH value and Al/F molar ratio of filtrate. This avant-garde approach illuminates a sustainable, ecologically harmonious route for synergistic disposal and high-value utilization of hazardous solid wastes from the aluminum smelting process.

Spectrophotometry and Histological Staining Potential of Ethanol Extract of brassica Oleracea (Red Cabbage) on Selected Organs of Sprague Dawley rat

Objective: Plants with coloring and dyeing effects have widely been used in histological staining. Natural dyes are less expensive, nontoxic, renewable and sustainable resources, with minimal environmental impact compared to synthetic stains. Red cabbage is one of such natural dyes. The red color of the red cabbage derived from anthocyanin pigments confers a great advantage to red cabbage. In this study, the physiochemical and spectrophotometric characteristics of red cabbage as well as its histological staining potentials on various tissues were carried out to determine its tissue specificity. Methods:The ethanol extract of red cabbage was prepared using 100% ethanol, then pH, spectrophotometry, and concentration of the red cabbage ethanol extract were measured before the solution was divided into two equal volumes, and one part was added with 2ml glacial acetic acid while the other part was added with 10g of aluminum sulfate. The two solutions were used to stain 10% neutral-buffered formalin-fixed, paraffin-wax-embedded tissue sections separately. Stained sections were viewed with a photomicroscope. Results: The ethanol extract was acidic at a pH of 4.89 and the spectrophotometry graph showed 3 peak absorbances at the wavelengths of 395nm, 545nm and 670nm. The maximum absorbance was 0.795 at the wavelength of 395nm and this is indicative of the pigment cyanidin which is the anthocyanin present in red cabbage. The red cabbage ethanol extract with both glacial acetic acid and aluminum sulfate showed good histological details in tissues of kidney, stomach, lungs, liver, spleen, small intestine and skin. There was no difference between the red cabbage ethanol extract and the conventional hematoxylin and eosin stain (P>0.05). Our study showed that red cabbage ethanol extract with acetic acid and aluminum sulfate is stable at 4oC, with color amber to light gold with a pH of 4.89 and a concentration of 1000 which gave good histological details. In general, our result indicates that red cabbage ethanol extract is an efficient stain for histological tissue structures and can be used as an eco-friendly alternative to eosin. Conclusion: Red cabbage ethanol extract stained basic structures of the cell such as the cytoplasm, muscle fibers and mucins. Therefore, red cabbage ethanol extract can be used in histological staining when appropriate modifications are done.

Total Lipid Content and Fatty Acid Composition of Two Morphologically Distinct Chlorella spp. for Biodiesel Production

This study investigated the potential of two morphologically distinct Chlorella spp. to assess the total lipid content and fatty acid composition targeting biodiesel production. Due to their rapid growth, less space requirement, and zero-conflict with current food demand, green microalgae-led biodiesel production has gained a key attention as an alternative, sustainable and eco-friendly substitute for fossil fuels diminishing the increased demand for fossil fuels, fuel prices and excessive release of greenhouse gases to the atmosphere. The Chlorella spp. were isolated from Beire Lake, Colombo (Wet Zone) and Kiriibban Lake, Monaragala (Dry Zone) of Sri Lanka. They were named as BCS1 and RCS2, respectively. Semi-mass culturing of Chlorella spp. in BG-11 medium (pH=7.5-8.5) was carried out in a greenhouse providing aeration and a 12:12 light: dark photoperiod. After 4 weeks, Chlorella spp. were harvested using aluminium sulphate, employing flocculation method. Harvested biomass was oven-dried and made into a fine powder for analysis. The total lipid content (TLC) of Chlorella spp. was determined using n-hexane as the extraction solvent in a soxhlet extractor maintaining three replicates for each. Extracted lipids were dried in a rotary evaporator and TLC was calculated gravimetrically. The total lipid content of BCS1 and RCS2 was recorded as 15.67% and 18.33%, respectively. After quantification, lipids were resuspended and concentrated in 1 mL of n-hexane to convert into fatty acid methyl esters (FAMEs)/ biodiesel via a transesterification reaction. The trans-esterified lipids (FAMEs) were analysed via Gas Chromatography. The most dominant FAMEs of BCS1 were palmitic acid (C16:0), oleic acid [C18:1 cis (n9)], stearic acid (C18:0), lignoceric acid (C24:0), lauric acid (C12:0) and myristic acid (C14:0). The most dominant FAMEs of RCS2 were cis-10-pentadecenoic acid (C15:1), elaidic acid [C18:1 trans (n9)], linolelaidic acid [C18:2 trans (n6)], cis-11-eicosenoic acid [C20:1 (n9)], lignoceric acid (C24:0) and oleic acid [C18:1 cis (n9)]. A well-balanced saturated and unsaturated FAME composition is essential for the optimal biodiesel quality, herein it was found in BCS1 with 41.62% of palmitic acid and 33.38% of oleic acid. Higher percentage of oleic acid exhibits a combination of oxidative stability and low temperature properties determining the suitability of BCS1 as a biodiesel feedstock compared to RCS2. In conclusion, even though RCS2 has a higher total lipid content, BCS1 exhibits more favourable characteristics in its FAME composition as a promising feedstock for biodiesel production.
 
 Keywords: Green microalgae, Chlorella spp., Total lipid content, Lipid composition, Biodiesel

Chemical recovery of magnesium from the Dead Sea and its use in wastewater treatment

Abstract The objective of this study was to establish a suitable chemical process to recover magnesium compounds from Dead Sea water using a selective precipitation process. The recovered magnesium hydroxide (Mg(OH)2) and magnesium chloride (MgCl2) are applicable for wastewater treatment processes since they can effectively remove total suspended solids (TSS) and chemical oxygen demand (COD). Magnesium salts recovered from Dead Sea water were compared with cationic polyacrylamide (PAM) and inorganic salts, including aluminum sulfate Al2(SO4)3, ferric chloride (FeCl3), and ferrous sulfate (Fe2SO4) to investigate the removal efficiency of TSS and COD from wastewater using a chemical precipitation method by using coagulation and flocculation process. Results show that Mg(OH)2 yielded the highest TSS and COD removal efficiencies of 59 and 57%, respectively, with a wastewater pH of 11.5. MgCl2 yielded lower removal efficiencies of 46 and 44%, respectively; at pH 10.5, lower magnesium concentration doses were needed. The most effective chemical precipitation method for removal involved cationic PAM coagulants, resulting in an 86% reduction in TSS and a 65% reduction in COD. Combining commercial Fe2SO4 and MgCL2 recovered from Dead Sea water reduced up to 90 and 73% of TSS and COD, respectively.

Exploring source water mixing strategies to reduce chemical consumption and environmental footprint in surface water treatment

Abstract Common methods for treating surface waters involve chemical flocculation, for which a significant factor contributing to the total cost and climate impact is the consumption of chemicals, chiefly coagulants and pH-adjusting chemicals. The amount of chemicals required for treating surface waters and achieving suitable flocculation pH depends greatly on the alkalinity of the source water. This study investigates the viability of mixing two surface waters with different chemical properties with the aim of reducing the amount of chemicals used during chemical flocculation. Bench-scale experiments were carried out, and the results were compared with full-scale operations at a surface water treatment plant (WTP). The WTP uses ferric chloride as a coagulant, which effectively removes natural organic matter, but consumes large amounts of hydroxide to manage pH before and after flocculation. As an alternative process, this study tested the use of aluminum sulfate, polyaluminum chloride and ferric chloride at varying dosages in combination with different source water mixtures to achieve suitable flocculation pH. The results showed that pH-adjusting chemicals could be omitted by adding a small amount of high alkalinity surface water to the primary source water, thereby reducing costs and climate impact substantially.