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Sewage sludge is an important soil conditioner, and source of nutrients with a potential for use in agriculture. However, such benefit needs to be weighed against the risks due to the presence of heavy metals, and other substances that may endanger human health, plants, soil and the ecosystem. This research had the objective of evaluating the agricultural potential of sewage sludge together with the risks that may be present in use. Samples of sewage sludge from seven wastewater treatment plants in Eswatini were analyzed for selected physical and chemical parameters, and heavy metal concentrations using commonly established laboratory procedures. The analysis results indicated that, sludge samples exhibited high organic matter content, cation exchange capacity, macro nutrients such as nitrogen and phosphorus and micro nutrients (trace metal elements) needed for plant growth. Anaerobically digested sludge samples showed higher carbon to nitrogen ratio because of biomass loss in the form of methane and carbon dioxide. The heavy metal concentrations are all within safe limits except the sludge from Matsapha area that had levels of chromium, and nickel above regulatory limits. With respect to their heavy metal contents, most of the sludge samples would qualify as Class A sludge ready to be used as organic fertilizer for agriculture without regular monitoring of heavy metals in the soil to which they are applied. The study results indicated the importance of sewage sludge for their agricultural potential through supplementation of both micro and macro nutrients needed for plant growth, for improving the soil properties such as water holding capacity and permeability, through the increase of organic matter content, and retention of nutrients due to the high cation exchange capacity. All these benefits are realized with sewage sludge being a lower cost alternative to commercial fertilizers. Moreover, the low concentration of heavy metals present in the sludge presents lower risk that may arise in the course of utilizing the sludge as agricultural supplement. Key words: Agriculture, fertilizer, heavy metals, nutrient, sewage, sludge, nitrogen, phosphorous, INTRODUCTION Sewage sludge is known to contain nutrients and trace elements that are required for growing plants. It is also a good soil conditioner that offers comparative advantages over mineral [...]

Thermally responsive polymers (TRP's) have gained significant attention in the past decade due to their unique phase transition behavior, those exhibiting changes in properties with temperature variations. In water, hydrophilic block copolymers form helical structures that can transform into hydrophobic globules above the lower critical solution temperature (LCST). Fouling is one of the limiting issues for the forward osmosis (FO) process in wastewater treatment. In this work, after the treatment of wastewater from the paper and pulp industries, foulants were removed from the surface of the commercial polyamide thin-film composite membrane of the FO process using polyvinyl methyl ether (PVME), a TRP with an LCST of 35-37[degrees]C. PVME was mixed with different aqueous solutions to form cleaning solutions. Foulant cleaning experiments utilized a 1% PVME (w/v) solution in 300 mL of de-ionized (DI) water, while 1 M NaCl solution served as the draw solution (DS) in the FO process. Comparing the water flux (J) and change in membrane hydraulic resistance (Rf) among pristine, fouled, and cleaned membranes revealed a 56.67% increase in water flux and a 51.68% decrease in membrane resistance after PVME mixed with DI water cleaning solution showcasing its effectiveness in improving membrane performance and reducing fouling. The cleaning efficiency of two solutions, that is, 1% PVME mixed in DI water and 1% PVME mixed in 1 M aqueous urea solution, is compared. Results showed that the former cleaning solution helped to obtain 32.62% higher water flux and 56.05% less membrane resistance. Various membrane characterizations are performed, such as field emission scanning electron microscopy (FE-SEM), which characterizes the membrane's pore structure and surface morphology, while a contact angle analyzer assesses hydrophilicity. This research highlights the use of TRPs as effective cleaning agents, enhancing membrane performance by effectively removing foulants on the membrane surface. Investigating alternative cleaning solutions also provides insights for optimizing water treatment processes. Highlights * Cleaning of fouled thin-film composite membrane using thermal-responsive polymers (TRPs). * Polyvinyl methyl ether, a TRP with an lower critical solution temperature of 35-37[degrees]C used as a cleaning agent. * 60% increase in water flux was observed after the single-step cleaning process. * Multiple uses of TRP for cleaning performed with no membrane damage. KEYWORDS cleaning solution, forward osmosis, membranes, thermal-responsive polymers, wastewater treatment, 1 | INTRODUCTION Approximately 71% of the Earth's surface is enveloped by water, while water constitutes about 65% of the human body's composition. (1) The exponential growth of the population [...]

To improve the adsorption and reusability of polypropylene (PP) fiber membranes, the organically modified saponite (Sap@P(St-co-MMA)) was prepared by solution polymerization. Furthermore, PP-based nanocomposite fiber membranes with strong oil adsorption, thermal stability, and reusability were prepared via melt-blown technology. The increased specific surface area of PP-based nanocomposite fiber membranes (PP-1.5%) provided more active sites for the oil adsorption. Simultaneous rheology and Fourier transform infrared measurements tests showed that Sap@P(St-co-MMA) enhanced the crystallinity of PP matrix, promoted the regular arrangement of molecules, and improved the intermolecular interaction force, which was beneficial for the oil adsorption. The adsorption of PP-1.5% (1.5 wt% addition of Sap@P(St-co-MMA)) fiber membrane for xylene and kerosene reached a maximum of 15.84 and 22.84 g [g.sup.-1], respectively. In the treatment of coal tar wastewater, the removal rate of oil can reach 62.9%, and the removal rate can still reach 51.17% after five cycles of experiments. In summary, PP-1.5% fiber membrane does not produce secondary pollution to the environment, and is a kind of oil removal material with good application prospect. Highlights * PP-based nanocomposites fiber membrane with strong oil adsorption was prepared. * Organically modified saponite had strong heterogenous nucleation for PP matrix. * Sap@P(St-co-MMA) increased the specific surface area of PP-based fiber membrane. KEYWORDS adsorption behavior, organically modified saponite, poly (propylene) nanocomposites fiber membranes, reusability, 1 | INTRODUCTION In recent years, with the rapid development of various enterprises such as coal chemical industry, resulting in the increasing of oily wastewater as well as the frequent [...]

Estimating the attenuation of nutrients (e.g., nitrogen, phosphorus) in groundwater from onsite wastewater treatment systems (OWTS) is difficult due to the costs and uncertainty associated with determining site-specific degradation rates, groundwater flow paths, and aquifer hydraulic properties. Some available methods allow users to specify natural degradation rates for nutrients from OWTS but provide inadequate guidance on how to determine those rates. Other methods use a mechanistic approach with numerous variables and equations that are known to affect nutrient attenuation but are necessarily complex and difficult to use for assessing hundreds or thousands of septic systems, as is often needed for regulatory applications. A spreadsheet analysis, the Method for Estimating Attenuation of Nutrients from Septic Systems (MEANSS), has been developed within the Montana Department of Environmental Quality to provide a relatively simple method of estimation with minimal data requirements. MEANSS is an empirical method designed to estimate the load of nutrients that will migrate to groundwater and surface water from OWTS sources. MEANSS provided comparable estimates of nitrogen and ortho-phosphorus attenuation below and downgradient of OWTS when evaluated against several field studies, a GIS-based nitrogen loading model, a mechanistic model, and a watershed model. Keywords: wastewater, nitrogen attenuation, phosphorus attenuation, septic system, nutrients, Introduction In 1990, approximately 25% of the U.S. population used onsite wastewater systems (commonly known as septic systems) to dispose of household wastewater; 1990 was the last year this information [...]

The escalating frequency of oil spill incidents and industrial wastewater discharges necessitates the development of effective remediation strategies. In this study, we conduct a comprehensive computational investigation using density functional theory (DFT) to elucidate the interaction mechanisms within polyethylene (PE) combined with polyurethane (PU) and hexane. The study focuses on adsorption energies, intermolecular interactions, miscibility, and electronic properties, providing a molecular-level understanding crucial for designing advanced absorbent materials. The investigation reveals that the low-density polyethylene/polyurethane (LDPE/PU) system exhibits significantly higher adsorption energies (-12.87 kcal/mol) compared to PE/hexane (-7.66 kcal/mol), indicating a robust binding affinity. This discrepancy underscores the superior performance of PE/PU as an absorbent material. The enthalpy results, with [DELTA]H values of -55.75 kcal/mol for PE/hexanen-hexadecane and -66.11 kcal/mol for PE/PU-n-hexadecane complexes at 298.15 K, support exothermic adsorption. The more exothermic [DELTA]H for PE/PU indicates stronger interactions during oil absorption than PE/hexane. Additionally, Gibbs free energy change ([DELTA]G) values affirm a more favorable process for PE/PU, exhibiting a lower [DELTA]G (-42.54 kcal/mol) compared to PE/hexane (-34.79 kcal/mol). Non-covalent interaction (NCI) studies confirm the importance of van der Waals forces in both systems, validating their role in the adsorption process. Miscibility studies indicate limited interactions, with PE/PU showing positive enthalpy of mixing. Electronic study demonstrates PE/PU's higher energy gap of 9.19 eV, correlating with superior performance. This research contributes to the fundamental understanding of oil absorption processes and informs the design and optimization of environmentally sustainable and efficient oil-absorbing materials for remediation applications. Highlights * DFT explores polymeric systems, PE/PU and PE/hexane, for oil absorbent. * PE/PU excels with -12.87 kcal/mol adsorption energy, surpassing PE/hexane (-7.66 kcal/mol). * NCI validates van der Waals forces in both systems, crucial for effective adsorption. * Miscibility studies reveal limited interactions. * PE/PU's superior 9.19 eV energy gap signifies enhanced absorbent performance. * PE/PU excels as an oil-absorbent material, underlining its overall superiority. KEYWORDS absorbent materials, density functional theory (DFT), n-hexadecane, polyethylene (PE), polyurethane, 1 | INTRODUCTION In recent years, the escalating frequency of oil spill incidents and industrial wastewater discharges has underscored the critical need for effective remediation strategies to mitigate environmental damage. [...]

Stenotrophomonas maltophilia and Ochrobactrum sp. demonstrated the highest rates of dye bioremediation. The trials were performed at pH 8, which resulted in the highest bioremediation rate of 64.6% in media containing 21.2 mg [L.sup.-1] dye. As the dye concentration increased, the pollutant removal decreased, with the maximum bioremoval rate of 70.3%. The removal capacity was increased with an increase in biomass concentration; the highest yield of 91.3% was obtained in media containing 14.2 mg [L.sup.-1] dye and 12% (v/v) biomass. In nanoremediation studies, the bacterial consortium was immobilized on cellulose acetate nanofiber mats (CA-NFM). Scanning electron microscopic micrographs showed that bead-free nanofiber mats were effective in immobilizing bacterial cells. Moreover, nanofiber structures were capable of supporting exopolysaccharides formation, as confirmed by Fourier transform infrared spectroscopy. The bacterial consortium immobilized on CA-NFM showed a maximum bioremoval rate of 56.5%. Reusability tests demonstrated that the consortium immobilized CA-NFM could be used at least five times. Furthermore, after leaving the mat for 1 month at 4[degrees]C, it was still usable, and the removal efficiency was found to be 45.4%. Based on our findings, bacteria immobilized on CA-NFM have the potential to be used as highly effective and versatile nanobiotechnological biological sorbents in the treatment of wastewater containing dyes. Highlights * Stenotrophomonas maltophilia and Ochrobactrum sp. were used as a bacterial consortium. * Bacterial consortium immobilized on cellulose acetate nanofiber mats (CA-NFM) was tested. * EPS production by the consortium was confirmed by Fourier transform infrared spectroscopy analysis. * CA-NFM could be used at least five times. KEYWORDS bacteria, cellulose acetate nanofiber, dye, nanoremediation, wastewater, 1 | INTRODUCTION As industrialization continues to grow, wastewater pollutants have become a concerning issue. Industrial wastewater contains a vast array of organic and inorganic compounds, including synthetic dyestuffs used [...]

Since the COVID-19 pandemic began, wastewater-based surveillance has been used to track circulation levels of SARS-CoV-2 (1,2). For that purpose, we began collecting samples from a regional wastewater treatment plant [...]

Electrospinning is a technique that can produce cost-efficient, large output, very permeable membranes with high surface-to-mass ratio, and be used for many different applications. In this research, poly(ether sulfone) (PES) electrospun fibers were prepared for potential application in oil/water separation. A comprehensive investigation was carried out to study how the performance of the electrospun fibers is influenced by various operating conditions and the composition of the solution. The electrospun mats were evaluated by SEM, tensile test, TGA, and water contact angle techniques. The morphology of the fabricated membranes has been altered due to changes in the process and solution parameters. This alteration is evident when comparing mats that have been solely electrospray to those with the highest density of junctions between the nanofibers. Due to the utilization of a combination of solvents, namely N,N-dimethylformamide, and N-methyl-pyrrolidinone (DMF/NMP), the mechanical properties of the fabricated membranes were enhanced. With this trick, a membrane with a tensile strength of 8.9 MPa was obtained, which had a relatively good performance in oil/water separation. This enhancement occurs through the improved fusion of inter-fiber junction points, which is facilitated by the presence of NMP, a high vapor pressure component, in the solvent mixture. Thermal analysis showed suitable thermal stability for a model of prepared membranes. The prepared PES membrane in optimum electrospinning condition, was used in the oil/water separation process and was found to be 80% efficient. Oil/water separation experiments for PES showed its bright future in the treatment of oil/water wastewater. Highlights * The effect of solution and process parameters was studied on PES electrospinning. * The tensile strength of the membrane was improved by using DMF/NMP solvent. * The PES membrane showed its bright future in the oil/water separation. KEYWORDS electrospinning, membrane, oil/water separation, optimization, poly/ether sulfone), 1 | INTRODUCTION Nanoscale materials with a one-dimensional structure (1D), like nanofibers, nanowires, nanotubes, and nanorods, are becoming more and more intriguing due to their distinctive chemical, electronic, mechanical, optical, [...]

Deacetylated cellulose acetate/thermoplastic polyurethane@graphene oxide (DA/TPU@GO) nanofibrous membranes were prepared through the combination of electrospinning, deacetylation, and ultrasound-assisted surface treatment techniques. The morphology, wettability, and mechanical properties of composite nanofiber membranes were studied via SEM, TEM, water contact angle measurements, and mechanical tests. Moreover, the adsorption capacity and mechanism of DA/TPU@GO nanofiber membranes for methylene blue and chromium (Cr (VI)) were analyzed. The introduction of active sites from GO led to a significant increase in the adsorption capacity of the DA/TPU@GO composite membranes compared with the DA/TPU composite nanofiber. The composite membrane featured adsorption capacities of 152.7 mg/g (25[degrees]C, pH 3) and 122.1 mg/g (25[degrees]C, pH 7) for Cr (VI) and methylene blue, respectively, which are higher than most other composite GO-based adsorbents. The adsorption mechanism of the DA/TPU@GO composite membrane was consistent with the Langmuir isotherm and second-order kinetic models. Therefore, the DA/TPU@GO composite nanofiber membrane served as an effective adsorbent with broad application prospects in the sewage treatment field owing to its excellent adsorption capacity. Highlights * Nanofibers were prepared for the absorption of methylene blue (MB) and Cr (VI). * Nanofibers exhibited adsorption capacities of 152.7 and 122.1 mg/g for Cr (VI) and MB. * Adsorption mechanism follows Langmuir isotherm and second-order kinetic models. * Nanofibers have wide potential applications in sewage treatment. KEYWORDS adsorption capacity, deacetylated cellulose acetate, electrospinning, oxide graphene, thermoplastic polyurethane, 1 | INTRODUCTION Numerous countries are faced with severe pollution issues that destroy aquatic flora and ecosystems, leading to the degradation of the human environment. Generally, water discharged from industries [...]

In this work, a novel SA/PEI/PDA([alpha])CNF (SPCP) aerogel adsorbent was prepared for efficient hexavalent chromium (Cr(VI)) and dyes removal. Sodium alginate was used as the skeleton ingredient, nanocellulose fiber as the reinforcing agent, while polyethyleneimine provides functional groups, and polydopamine was added to improve the adsorption capacity of the aerogel toward cationic dyes. Several methods were used to characterize the SPCP aerogel, and thorough research showed that the aerogel's adsorption capacities for CR, Cr(VI), and MB were 1078.06, 2827.38, and 596.96 mg/g, respectively. In addition, it was established that the pseudo-second-order kinetics provides the most accurate way to the adsorption kinetic process while the Langmuir model provides the most accurate representation of the adsorption isotherm. Additionally, SPCP aerogel still retained exceptional adsorption capability after five adsorption-desorption cycles. Thereupon, SPCP, this biomass composite aerogel exhibits notable benefits, such as high adsorption capacity, marvelous sustainability, cost-effectiveness, and easy operation, which was considered to be a promising adsorbent for the wastewater treatment. KEYWORDS adsorption, aerogel, cationic and anionic dyes, hexavalent chromium, 1 | INTRODUCTION Despite the rapid industrial development and growing urbanization, large amounts of industrial effluents were discharged into the environment, which threatens human health and ecosystem seriously. (1,2) Chromium, [...]

Water pollution has emerged as a formidable issue of utmost concern in the world, and the design of three-dimensional porous, high adsorption performance, and sustainable adsorbent materials is of great significance for wastewater purification. Naturally abundant sodium alginate was used to prepare oxidized sodium alginate (OSA), a biomass macromolecule containing an aldehyde group. A double network interpenetrating structure based on carboxymethyl chitosan (CMS) and OSA was constructed without any small molecule cross-linking agent throughout, and a Schiff base reaction occurred at room temperature to prepare chemically stable CMS@OSA aerogels, which contain a continuous and dense porous structure inside the aerogel. CMS and OSA both contain an anionic reactive group, carboxyl, which makes them both matrix and functional materials, enabling selective adsorption of malachite green (MG) dyes. The prepared aerogel adsorbent showed a high adsorption capacity (302 mg/g) for MG at room temperature. The adsorption mechanism between the aerogel adsorbent and the adsorbent mass was investigated, and the effect of different factors on the adsorption performance was analyzed. The fitting coefficients of both the adsorption kinetic model and the isotherm model reached 0.99. The ingenious preparation method and excellent adsorption performance offer great prospects for chitosan biomass aerogels to play a role in environmental protection and economy. Highlights * An interpenetrating structure based on the Schiff base reaction. * Construction of three-dimensional porous structures. * Pure ecological raw materials without toxic crosslinkers. * High adsorption capacity at 302 mg/g for malachite green. KEYWORDS adsorption, aerogel, chitosan, malachite green, sodium alginate, 1 | INTRODUCTION Water is considered to be the most important natural resource for human survival. A healthy and adequate water supply is the basis for human well-being and an [...]