Sustainable Cleaning Research Articles

A review on arsenic pollution, toxicity, health risks, and management strategies using nanoremediation approaches.

Over 50 countries are affected by arsenic contamination. The problem is becoming worse as the number of affected people increases and new sites are reported globally. Various human activities have increased arsenic pollution, notably in both terrestrial and aquatic environments. Contamination of our water and soil by arsenic poses a threat to our environment and natural resources. Arsenic poisoning harms several physiological systems and may cause cancer and death. Excessive exposure may cause toxic build-up in human and animal tissues. Arsenic-exposed people had different skin lesion shapes and were vulnerable to extra arsenic-induced illness risks. So far, research shows that varying susceptibility plays a role in arsenic-induced diseases. Several studies have revealed that arsenic is a toxin that reduces metabolic activities. Diverse remediation approaches are being developed to control arsenic in surrounding environments. A sustainable clean-up technique (nanoremediation) is required to restore natural equilibrium. More research is therefore required to better understand the biogeochemical processes involved in removing arsenic from soils and waters.

Marble Chromatic Alteration Study Using Non-Invasive Analytical Techniques and Evaluation of the Most Suitable Cleaning Treatment: The Case of a Bust Representing Queen Margherita di Savoia at the U.S. Embassy in Rome

In spite of the application of different cleaning procedures, the marble used for the portrait bust of Queen Margherita di Savoia continued to show permanent discoloration, consisting of an unevenly distributed grayish alteration, mainly on the front part. In this work, a multi-analytical, non-invasive approach was proposed using spectrocolorimetry, reflectance spectroscopy and multispectral imaging. The initial assumption, suggesting the presence of altered protective materials based on organic products (such as waxes or oils,) applied in the past according to traditional practices, was excluded, revealing instead the presence of deposits of particulate matter, which penetrated inside the crystalline structure of the marble, leading to a variation in its shade. Cleaning tests were also carried out to define the best product, using sustainable chemicals such as Polar Varnish Rescue®, alkoxyde surfactant, disodium EDTA, GLDA and Politect® Base in order to identify the best methodology and materials for sustainable cleaning, respecting the integrity of the original matter. Politect® Base demonstrated better action in comparison to the other products tested, and similar results were obtained with GLDA, which could be applied in areas where the Politect® is less efficient (e.g., lace).

Effectiveness of combination of heat water disinfection, continuous water circulation, and minimalized dead space for dialysis piping in maintaining ultrapure dialysis fluid and preventing biofilm formation in a central dialysis fluid delivery system.

Various benefits have been attached to purifying the dialysis fluid used for hemodialysis therapy. The central dialysis fluid delivery system can treat approximately 50 dialysis patients simultaneously and is convenient to operate. In contrast, the dialysis fluid supply piping is complicated, and bacterial growth can cause biofilms. This study aimed to develop sustainable cleaning strategies to solve the complicated dialysis fluid piping, which is a weakness of the central dialysis fluid delivery system, and provide ultrapure dialysis fluid for a long term. Combination of heat water disinfection, continuous water circulation, and minimalized dead space in the dialysis piping were designed for a central dialysis fluid delivery system and used in a clinic for 6years. As an index of water purification, endotoxin concentrations and microbial colony counts in reverse osmosis water and dialysis fluid were measured. In addition, we performed scanning electron microscopy of the silicon tube surface that had been used for 5years to confirm the presence or absence of biofilm formation. For 6years, endotoxin concentrations and microbial colonies were not detected in reverse osmosis water and dialysis fluid using the multiple-patient dialysis fluid supply equipment. The purity of the dialysis fluid was maintained. No biofilm formation was observed by scanning electron microscopy. Combination of heat water disinfection, continuous water circulation, and minimalized dead space designs for dialysis piping can supply ultrapure dialysis fluid with minimal biofilm formation in the piping in the long term.

Environmental and human health implications of metal(loid)s: Source identification, contamination, toxicity, and sustainable clean-up technologies

Environmental pollution is becoming more prevalent in both human life and the ecosystem. The increased use of fossil fuels, mining, and the burning of wastes, as well as industrial wastewater discharge, are polluting natural resources such as water, soil, and air. Metals (loid)s (Cu, Cr, Cd, Zn, Ni, Pb, Hg, Sb, Sn, and As) contribute to several ecological problems when exposed to humans and the environment resulting in serious health and environmental risks. The pollution of aquatic and terrestrial sites with these elements is an issue of environmental as well as public health significance. The present review highlights environmental problems instigated by the toxic metal (loid)s, their source, and respective health/environmental concern along with the importance of creating low-cost, environmentally acceptable clean-up technologies for treating household and industrial wastewater. Various physical, chemical, biological, and/or biochemical as well as their various combinations have been described from the sustainable technological point of view. Techniques such as ion exchange, membrane filtration, photocatalysis, bioremediation, phytoremediation, economical biosorbents, and nanomaterials have been discussed in detail along with respective recent case studies to gain a significant inside towards the solution of the environmental problems focused and action-oriented sustainable technologies development. Thus, this article significantly provides a deep insight into metal (loid)s toxicity, source identification, and their influences on the ecosystem and human health along with conventional and sustainable clean-up technologies.

Influence of electrolytes on the structural and viscosity properties of mixed anionic–nonionic–zwitterionic surfactants in detergent formulations

AbstractCleaning products have a global market of around $33 billion in 2020 and play an essential role in daily life, providing consumers with important public health benefits. Surfactants are the main ingredients of cleaning products and they can effectively remove dirt, germs, and other contaminants from surfaces. Understanding the role of each surfactant class in a detergent formulation and their interaction with NaCl is of utmost importance for formulating efficient and sustainable cleaning products. This paper describes the study of ternary surfactant systems consisting of surfactants (sodium lauryl ether sulfate, alkyl polyglycoside, or betaine, three of the most commonly used surfactants in detergent formulations), water, and NaCl. The effects of concentration on critical micelle concentration, aggregate size, and rheological behavior were evaluated by dynamic light scattering and rheology techniques.

Managing microbes

Managing microbes

Highly selective and sustainable clean-up of phosphate from aqueous phase by eco-friendly lanthanum cross-linked polyvinyl alcohol/alginate/palygorskite composite hydrogel beads

The development of feasible adsorbent for phosphate removal is of great urgency to remediate water eutrophication and maintain sustainable development of water resources. In the present work, eco-friendly lanthanum cross-linked polyvinyl alcohol/alginate/palygorskite (LPAP) composite hydrogel beads were synthetized for phosphate removal from aqueous solution. The encapsulation of palygorskite (PAL) into polymers enhanced the mechanical strength of LPAP hydrogel and selectivity towards phosphate as well. The characterization of synthesized hydrogel was conducted by SEM-EDS, BET, XRD, FT-IR and XPS, etc. Batch experiments indicated that phosphate uptake by LPAP was pH dependent with the optimal pH range of 3–6, and efficient phosphate removal (nearly 100%) was maintained in the co-existence of anions (Cl−, NO3− and SO42−). The adsorptive behavior of LPAP beads could be satisfactorily described by Freundlich isotherm model and pseudo-second-order kinetic model, with the experimental maximum phosphate uptake of ∼33.2 mg/g obtained at pH 4. Thermodynamics analysis suggested the spontaneous and endothermic character of adsorption process. More crucially, the superior reusability of LPAP beads confirmed through sorption-desorption cyclic experiments provided access for waste elimination at the minimum cost. The main phosphate removal routes were identified as electrostatic interaction, ligand exchange and Lewis acid-base interaction, and crystalline LaPO4·xH2O was formed on the surface of LPAP beads. Overall results demonstrated the applicable potential of LPAP beads as an environmental-sustainable, low-cost, anti-interfering and easily-recovered biosorbent for environmental remediation.

Preparation and adsorption properties of magnetic hydrophobic cellulose aerogels based on refined fibers

A novel approach was introduced to prepare very low density, highly porous, economic, reusable, hydrophobic, and magnetic cellulose aerogels from hardwood dissolving pulp via a simple freeze-drying procedure. The aerogels showed outstanding adsorption efficiency for several oils and organic solvents and demonstrated excellent selectivity for absorbing oil from an oil/water mixture. Moreover, they were easily collected by an external magnet, indicating excellent recyclability and reusable for at least 10 cycles while still retaining supreme adsorption capacity (up to 181 g/g for silicone oil). This study proposes an economic and novel method for the large-scale preparation of hydrophobic and magnetic cellulose aerogels, making them a promising candidate for the efficient and sustainable cleaning of oils and chemical spills.

Isolation of a soil bacterium for remediation of polyurethane and low-density polyethylene: a promising tool towards sustainable cleanup of the environment.

The online version contains supplementary material available at 10.1007/s13205-020-02592-9.

Enhanced hydraulic cleanability of biofilms developed under a low phosphorus concentration in reverse osmosis membrane systems

A critical problem in seawater reverse osmosis (RO) filtration processes is biofilm accumulation, which reduces system performance and increases energy requirements. As a result, membrane systems need to be periodically cleaned by combining chemical and physical protocols. Nutrient limitation in the feed water is a strategy to control biofilm formation, lengthening stable membrane system performance. However, the cleanability of biofilms developed under various feed water nutrient conditions is not well understood.This study analyzes the removal efficiency of biofilms grown in membrane fouling simulators (MFSs) supplied with water varying in phosphorus concentrations (3 and 6 μg P·L-1 and with constant biodegradable carbon concentration) by applying hydraulic cleaning after a defined 140% increase in the feed channel pressure drop, through increasing the cross-flow velocity from 0.18 m s-1 to 0.35 m s-1 for 1 h. The two phosphorus concentrations (3 and 6 μg P·L-1) simulate the RO feed water without and with the addition of a phosphorus-based antiscalant, respectively, and were chosen based on measurements at a full-scale seawater RO desalination plant. Biomass quantification parameters performed after membrane autopsies such as total cell count, adenosine triphosphate, total organic carbon, and extracellular polymeric substances were used along with feed channel pressure drop measurements to evaluate biofilm removal efficiency. The outlet water during hydraulic cleaning (1 h) was collected and characterized as well. Optical coherence tomography images were taken before and after hydraulic cleaning for visualization of biofilm morphology.Biofilms grown at 3 μg P·L-1 had an enhanced hydraulic cleanability compared to biofilms grown at 6 μg P·L-1. The higher detachment for biofilms grown at a lower phosphorus concentration was explained by more soluble polymers in the EPS, resulting in a lower biofilm cohesive and adhesive strength. This study confirms that manipulating the feed water nutrient composition can engineer a biofilm that is easier to remove, shifting research focus towards biofilm engineering and more sustainable cleaning strategies.

Influence of organic fouling layer characteristics and osmotic backwashing conditions on cleaning efficiency of RO membranes

Fouling remains a prevalent and serious problem in industries using membrane processes. Efforts to mitigate fouling are improving, however, membrane fouling cannot be completely eliminated. Therefore fouling control via development of sustainable cleaning methods are crucial. Despite osmotic backwashing showing promise, little is understood about this cleaning method for removal of fouling from reverse osmosis (RO) membranes. This paper systematically examines how organic fouling characteristics and osmotic backwashing parameters influence cleaning efficiency. Alginic acid was used as a model foulant and numerous microscopy techniques, including confocal microscopy, scanning electron microscopy and atomic force microscopy were used to examine the membrane fouling before and after cleaning to gain a clearer understanding of the mechanisms involved. Increasing CaCl2 concentration in the fouling solution resulted in an increase in fouling layer thickness from 37 to 179 μm, due to the complexation of Ca2+ and the carboxyl groups in the alginate. Osmotic backwashing efficiency with 0.7 M NaCl decreased as the fouling layer became thicker and the pure water flux (PWF) recovery decreased from 92% to 81%. Osmotic backwashing efficiency also decreased with increasing initial permeate flux, as less fouling was removed: the fouling generated at higher initial fluxes is largely irreversible, resulting in a denser and more compact fouling layer. In an effort to increase osmotic backwashing flux, a CaCl2 draw solution was used, however, the Ca2+ ions were found to interact with the alginate in the fouling layer, rendering this method inefficient, when compared to NaCl draw solutions which originated similar osmotic backwashing fluxes. Interestingly, the fouling layer was found to swell from 16 μm to 141 μm, when osmotic backwashing was carried out with a NaCl draw solution, followed by contact with a low ionic strength solution used for PWF testing. This phenomenon does not occur to the same extent after backwashing with CaCl2. The same trends were obtained for bovine serum albumin (BSA) fouling, whilst humic acid (HA) did not display any swelling phenomena. However, it showed the same cleaning inefficiency when using CaCl2 as a draw solution.

Electrolyzed water as a sustainable cleaning and disinfection chemical for SMEs Malaysian meat processing food industries: Challenges and uncertainties

The cleaning and disinfection are also known as sanitation process and it is a prerequisite for most of food safety standards. Sanitation process is often neglected by industrialist due to it is a plant downtime and incurs cost. Limited resources and knowledge have prevented the implementation of effective cleaning and sanitation process in the Small and Medium-sized Enterprises (SMEs) food factories in Malaysia. The commercial food-grade chemical which is expensive can be a burden for SMEs food manufacturers. Hence some of the SMEs food manufacturers have opted for non-food grade cleaning chemicals (e.g., laundry detergent) to clean their food processing equipment and factory environment. The non-food grade chemical is less rinsible and can leave a fragrance. The application of this non-food grade chemical not only caused chemical contamination to food products but also on riverine. The improper disposal of wastewater sourcing from the Malaysian food industry is known to pose pollution problems and violate environmental regulation. The odourless and rinsible electrolyzed water (EW) is seen as a potential alternative for the commercial cleaning and sanitation detergents. Moreover, papers are claiming that there is no wastewater treatment are needed when the EW is used as the cleaning and disinfecting chemicals.

Augmentation of stimulated Pelomonas aquatica dispersible granules enhances remediation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated soil

Abstract In this study, we explored the hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) degradation potential of a gram-negative bacterium Pelomonas aquatica strain 12868. The microbe eliminated 80.68% of RDX by utilizing the explosive as a nitrogen source. FTIR study and nitrite assay confirmed the degradation of RDX into non-toxic metabolites in an RDX-succinate aqueous medium. The isolate showed an improved RDX degradation when formulated into water dispersible granules (WDG) using soy flour as a nutrient source. The WDG formulation not only achieved 6.53% enhanced RDX degradation but also stabilized the microbe as only a 24.37% decrease in cfu count was observed after a storage period of six months at 30 oC. During the microcosm experiments, RDX degradation followed first-order kinetics with a half-life of 13.9 and 19.04 days in a soil biostimulated by sucrose and wheat straw, respectively. P. aquatica with sucrose as added carbon source effectively degraded 50.91% more RDX compared to unstimulated control after 30 days of treatment. These data imply that microbial formulation mediated RDX reduction coupled with biostimulation has the potential to become a swift and sustainable clean-up approach for RDX contaminated environments.

Interpretation of lead removal by two biomasses at different size via monitoring the solution environment

It is imperative to seek for a quick monitoring method in the sustainable cleanup of heavy metal contaminated water and in the efficient use of waste biomass resources. In this study, SMS (spent mushroom substrate) and CSMS (composted spent mushroom substrate) were processed into particles at different size for the lead removal from solution. The results indicate that biomass particles at different size are inconsistent in functional groups characteristics. In batch experiments, changes in pH and EC (electric conductivity) can explicate the lead removal process and the effect of particle size and dissolved matter on removal rate. The established removal rate models based on pH and EC value (p˂0.01) can be used to assess the efficiency of particles in lead removal. In fixed-bed experiment, lead removal rate is highly correlated with pH value (0.763–0.986, p˂0.01). The present study provides a quick method for monitoring the removal efficiency of waste biomass in the treatment of metal contaminated water.

Magnetic superabsorbents based on nanocellulose aerobeads for selective removal of oils and organic solvents

Superabsorbent aerogels are fascinating materials for oil and chemical spillage cleanup. However, the development of an economic and efficient superabsorbent is still highly challenging. In this study, we introduce a novel approach to prepare very low density (0.005 g/cm3), highly porous (>99.6%), economic, reusable, hydrophobic, and magnetic spherical cellulose nanofiber-derived aerogels (i.e., aerobeads) prepared from waste boxboards via a simple freeze-drying procedure. The spherical aerobeads were fabricated easily after dropping a hydrophobized nano-fibrillated cellulose solution containing magnetic Fe3O4 nanoparticles into liquid nitrogen. The aerobeads showed outstanding absorption efficiency for several oils and organic solvents (up to 279 g/g with castor oil) and demonstrated excellent selectivity for absorbing oil from an oil/water mixture. Moreover, they were easily collected by an external magnet, indicating excellent recyclability and reusable for at least 10 cycles while still retaining supreme absorption capacity (up to 101 g/g for diesel oil). This study proposes an economic and novel method for the large-scale preparation of spherical superabsorbent aerobeads, making them a promising candidate for the efficient and sustainable cleaning of oil and chemical spills.

Suicidal germination as a control strategy for Striga hermonthica (Benth.) in smallholder farms of sub‐Saharan Africa

Societal Impact StatementInfestation by the parasitic plant Striga hermonthica is a severe threat to food security in sub‐Saharan Africa, impacting the production of the major staple crops pearl millet and sorghum, equating to 7–10 billion $ losses. Using Striga seed dependency on host‐released germination stimulants, we have developed and validated a method for addressing the problem of accumulated parasite seedbanks—the major obstacle in combating Striga infestation in African rain‐fed fields. Application of our method promises to alleviate the problem posed by this pernicious weed by increasing crop production for smallholder farmers. Summary The root parasitic plant Striga hermonthica is a major threat to global food security, causing enormous losses in yields of the main staple crops in sub‐Saharan Africa, which include pearl millet, sorghum, maize and rice. Sustainable Striga control should ideally lead to the depletion of the vast, long‐lived Striga seedbank, and this can be achieved by inducing suicidal seed germination through application of strigolactone (SL) analogs in the absence of host plants. However, this “suicidal germination” strategy has not been evaluated under the natural rain‐fed conditions that prevail in Striga‐prone regions. We have developed and validated a protocol for suicidal germination in laboratory and natural conditions in Striga‐infested rain‐fed African fields. Three SL analogs were tested and these resulted to between 65% and 55% reduction in Striga emergence in pearl millet and sorghum fields, respectively. We conclude that suicidal germination is an effective method for reducing the Striga seedbank. Moreover, the minimal demands of our protocol, in terms of water consumption and amount of selected SL analogs, make it affordable and applicable at a large scale in African rain‐fed agriculture, holding promise for sustainable cleaning of heavily Striga‐infested fields in sub‐Saharan Africa.

Easy preparation of recyclable thermally stable visible-light-active graphitic-C3N4/TiO2 nanocomposite photocatalyst for efficient decomposition of hazardous organic industrial pollutants in aqueous medium

Graphitic-C3N4/TiO2 nanocomposite was prepared as a photocatalyst (PC) active under visible light (λ ≥ 420 nm) by preparation of graphitic carbon nitride (g-C3N4) from melamine followed by an effective easy impregnation method. Several g-C3N4/TiO2 composites containing 1 to 12 wt% g-C3N4 were synthesized and characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), photoluminescence (PL) spectroscopy, diffusion reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) measurements. A photocatalytic mechanism is proposed based on the relative positions of the energy bands of the two constituents. Compared with its individual components, g-C3N4/TiO2 demonstrated unusually high photocatalytic activity for phenol decomposition in aqueous phase under visible-light irradiation. The heterojunction was optimized in the 5 wt% g-C3N4/TiO2 nanocomposite due to the well-matched bandgap structure (optimum loading) and excellent electron–hole pair separation in the conduction and valence band of TiO2 and g-C3N4, respectively. After 2 h of visible-light irradiation, 68 % degradation was observed when using this optimum composition. The performance was slightly decreased (to 66 %) after recycling of the catalyst four times (used a total of five times), but remained reliable for industrial applications considering other factors. In this system, TiO2 (Degussa P25) seems to play the principal PC role, while g-C3N4 acts as a sensitizer for absorption of visible light. Due to the enhanced visible-light absorption ability enabled by g-C3N4 in the composite, stable electron–hole (e−–h+) pairs produced at the interface of the heterojunction lead to generation of highly reactive free radicals (·O2, ·OH, etc.) which together initiate degradation of phenol but individually suffer from some limitation that must be overcome. The thermal stability and recycling efficiency of this PC will enable its use in industrial applications as a cost-effective sustainable cleanup candidate. The prepared g-C3N4/TiO2 exhibits stable electron–hole (e−–h+) pair separation at the heterojunction under visible light for enhanced degradation of organic pollutants via a redox mechanism. The g-C3N4 loading affects the photocatalytic activity, with the 5 wt% g-C3N4/TiO2 composite exhibiting the highest degradation, with recycling.

A Review of Conventional and Innovative- Sustainable Methods for Cleaning Reflectors in Concentrating Solar Power Plants

The severe soiling of reflectors deployed in arid and semi arid locations decreases their reflectance and drives down the yield of the concentrating solar power (CSP) plants. To alleviate this issue, various sets of methods are available. The operation and maintenance (O&M) staff should opt for sustainable cleaning methods that are safe and environmentally friendly. To restore high reflectance, the cleaning vehicles of CSP plants must adapt to the constraints of each technology and to the layout of reflectors in the solar field. Water based methods are currently the most commonly used in CSP plants but they are not sustainable due to water scarcity and high soiling rates. The recovery and reuse of washing water can compensate for these methods and make them a more reasonable option for mediterranean and desert environments. Dry methods, on the other hand, are gaining more attraction as they are more suitable for desert regions. Some of these methods rely on ultrasonic wave or vibration for detaching the dust bonding from the reflectors surface, while other methods, known as preventive methods, focus on reducing the soiling by modifying the reflectors surface and incorporating self cleaning features using special coatings. Since the CSP plants operators aim to achieve the highest profit by minimizing the cost of cleaning while maintaining a high reflectance, optimizing the cleaning parameters and strategies is of great interest. This work presents the conventional water-based methods that are currently used in CSP plants in addition to sustainable alternative methods for dust removal and soiling prevention. Also, the cleaning effectiveness, the environmental impacts and the economic aspects of each technology are discussed.

Extremophilic Microfactories: Applications in Metal and Radionuclide Bioremediation.

Metals and radionuclides (M&Rs) are a worldwide concern claiming for resilient, efficient, and sustainable clean-up measures aligned with environmental protection goals and global change constraints. The unique defense mechanisms of extremophilic bacteria and archaea have been proving usefulness towards M&Rs bioremediation. Hence, extremophiles can be viewed as microfactories capable of providing specific and controlled services (i.e., genetic/metabolic mechanisms) and/or products (e.g., biomolecules) for that purpose. However, the natural physiological plasticity of such extremophilic microfactories can be further explored to nourish different hallmarks of M&R bioremediation, which are scantly approached in the literature and were never integrated. Therefore, this review not only briefly describes major valuable extremophilic pathways for M&R bioremediation, as it highlights the advances, challenges and gaps from the interplay of ‘omics’ and biological engineering to improve extremophilic microfactories performance for M&R clean-up. Microfactories’ potentialities are also envisaged to close the M&R bioremediation processes and shift the classical idea of never ‘getting rid’ of M&Rs into making them ‘the belle of the ball’ through bio-recycling and bio-recovering techniques.

Phytoremediation removal rates of benzene, toluene, and chlorobenzene

ABSTRACTPhytoremediation is a sustainable remedial approach, although performance efficacy is rarely reported. In this study, we assessed a phytoremediation plot treating benzene, toluene, and chlorobenzene. A comparison of the calculated phytoremediation removal rate with estimates of onsite contaminant mass was used to forecast cleanup periods. The investigation demonstrated that substantial microbial degradation was occurring in the subsurface. Estimates of transpiration indicated that the trees planted were removing approximately 240,000 L of water per year. This large quantity of water removal implies substantial removal of contaminant due to large amounts of contaminants in the groundwater; however, these contaminants extensively sorb to the soil, resulting in large quantities of contaminant mass in the subsurface. The total estimate of subsurface contaminant mass was also complicated by the presence of non-aqueous phase liquids (NAPL), additional contaminant masses that were difficult to quantify. These uncertainties of initial contaminant mass at the site result in large uncertainty in the cleanup period, although mean estimates are on the order of decades. Collectively, the model indicates contaminant removal rates on the order of 10−2–100 kg/tree/year. The benefit of the phytoremediation system is relatively sustainable cleanup over the long periods necessary due to the presence of NAPL.