The Use of Clay-Polymer Nanocomposites in Wastewater Pretreatment

Some agricultural effluents are unsuitable for discharge into standard sewage-treatment plants: their pretreatment is necessary to avoid clogging of the filtering devices by colloidal matter. The colloidal stability of the effluents is mainly due to mutual repulsive forces that keep charged particles in suspension. Pretreatment processes are based on two separate stages: (a) neutralization of the charges (“coagulation”) and (b) bridging between several small particles to form larger aggregates that sink, leaving clarified effluent (“flocculation”). The consequent destabilization of the colloidal suspension lowers total suspended solids (TSSs), turbidity, and other environmental quality parameters, making the treatments that follow more efficient. Clay-based materials have been widely used for effluent pretreatment and pollutant removal. This study presents the use of nanocomposites, comprised of an anchoring particle and a polymer, as “coagoflocculants” for the efficient and rapid reduction of TSS and turbidity in wastewater with a high organic load. The use of such particles combines the advantages of coagulant and flocculant by neutralizing the charge of the suspended particles while bridging between them and anchoring them to a denser particle (the clay mineral), enhancing their precipitation. Very rapid and efficient pretreatment is achieved in one single treatment step

Combined bioremediation and enzyme production by Aspergillus sp. in olive mill and winery wastewaters

Olive mill wastewaters (OMW) and vinasses (VS) are effluents produced respectively by olive mills and wineries, both sectors are of great economic importance in Mediterranean countries. These effluents cause a large environmental impact, when not properly processed, due to their high concentration of phenolic compounds, COD and colour. OMW may be treated by biological processes but, in this case, a dilution is necessary, increasing water consumption. The approach here in proposed consists on the bioremediation of OMW and VS by filamentous fungi. In a screening stage, three fungi (Aspergillus ibericus, Aspergillus uvarum, Aspergillus niger) were selected to bioremediate undiluted OMW, two-fold diluted OMW supplemented with nutrients, and a mixture of OMW and VS in the proportion 1:1 (v/v). Higher reductions of phenolic compounds, colour and COD were achieved mixing both residues; with A. uvarum providing the best results. In addition, the production of enzymes was also evaluated during this bioremediation process, detecting in all cases lipolytic, proteolytic and tannase activities. A. ibericus, A. uvarum and A. niger achieved the highest value of lipase (1253.7 ± 161.2 U/L), protease (3700 ± 124.3 U/L) and tannase (284.4 ± 12.1 U/L) activities, respectively. Consequently, this process is an interesting alternative to traditional processes to manage these residues, providing simultaneously high economic products, which can be employed in the same industries.Supported by the grant SFRH/BPD/84440/2012 and SFRH/BPD/43922/2008 respectively, from Fundação para a Ciência e Tecnologia – FCT, Portugal. Fundação para a Ciência e a Tecnologia (FCT) for financial support through the project FCT Pest-OE/EQB/LA0023/2011. Also, authors thank the Project “BioInd – Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028” Co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDE

The Use of ATR-FTIR Spectroscopy for Quantification of Adsorbed Compounds

Quantification of adsorbed amounts requires in most cases several assumptions. Adsorption of organic compounds, for example, is usually measured indirectly, by mass balance calculations based on the evaluation of the remaining chemical in solution. Such procedure might yield overestimates when precipitation or degradation of the adsorbate occurs and underestimates when separation of the sorbent material (e.g., clay particles) with the adsorbed chemical is not effective. This study presents a simple quantification procedure based on the ratio between IR absorption bands of the sorbate and the adsorbate. The advantages of the procedure are (a) direct evaluation of the adsorbed amount and (b) accurate measurement of chemicals that are hard to quantify, as those that do not absorb light in the UV-Visible range, or require expensive chromatography procedures

Assessment of Arthrobacter viscosus as reactive medium for forming permeable reactive biobarrier applied to PAHs remediation

Polycyclic aromatic hydrocarbons (PAHs) are significant environmental contaminants as they are present naturally as well as anthropogenically in soil, air and water. In spite of their low solubility, PAHs are spread to the environment, and they are present in surface water, industrial effluent or groundwater. Amongst all remediation technologies for treating groundwater contaminated with PAHs, the use of a permeable reactive biobarrier (PRBB) appears to be the most cost-effective, energy efficient, and environmentally sound approach. In this technology, the microorganisms are used as reactive medium to degrade or stabilize the contaminants. The main limits of this approach are that the microorganisms or consortium used for forming the PRBB should show adequate characteristics. They must be retained in the barrier-forming biofilm, and they should also have degradative ability for the target pollutants. The aim of the present work is to evaluate the viability of Arthrobacter viscosus as bioreactive medium for forming PRBB. Initially, the ability of A. viscosus to remove PAHs, benzo[a]anthracene 100 μM and phenanthrene 100 μM was evaluated operating in a batch bench-scale bioreactor. In both cases, total benzo[a]anthracene and phenanthrene removals were obtained after 7 and 3 days, respectively. Furthermore, the viability of the microorganisms was evaluated in the presence of chromium in a continuous mode. As a final point, the adhesion of A. viscosus to sepiolite forming a bioreactive material to build PRBB was demonstrated. In view of the attained results, it can be concluded that A. viscosus could be a suitable microorganism to form a bioreactive medium for PAHs remediation.This work has been supported by the Spanish Ministry of Economy and Competitiveness and FEDER Funds (Project CTM 2011-25389). Marta Pazos received financial support under the Ramon y Cajal programme and Marta Cobas under the final project master grant "Campus do Mar Knowledge in depth"

Adsorption of benzyltrimethylammonium to montmorillonite: application to herbicide formulations Adsorption du benzyltriméthylammonium sur la montmorillonite: application à la …

MATERIALS AND METHODS The clay mineral used was Wyoming Na-montmorillonite SWy-1 obtained from the Source Clays Repository (Clay Minerals Society, Columbia, MO). BTMA was purchased from Aldrich (Milwaukee, WI, USA). Analytical grade alachlor (Chem Service, West Chester, PA) was used for making the formulations, whereas a commercial formulation (EC)(Alanex, 480g ai/kg, Agan Chemical Manufactures LTD., Ashdod, Israel) was used as a standard formulation. The electrolytes used were: NaCl, LiCl, NaClO4, Na2SO4, CsCl

Optimization of adsorption of hydrophobic herbicides on montmorillonite preadsorbed by monovalent organic cations: interaction between phenyl rings

This study aimed to optimize organo-clay formulations for reduction of leaching of the herbicides alachlor, metolachlor, and norflurazon, which include a phenyl ring in the structure. The adsorbed amounts of herbicides increased severalfold when montmorillonite was preadsorbed by an organic cation; benzyltrimethylammonium (BTMA) was more effective than benzyltriethylammonium (BTEA). Fourier transform infrared studies indicated interactions between alachlor molecules and adsorbed BTMA. The adsorption affinity of the herbicides increased with BTEA loading up to the cation exchange capacity (CEC) of montmorillonite but reached a maximum at a BTMA loading of 5/8 of the CEC. The enhanced adsorbed amounts of herbicides are mainly due to interactions between the phenyl rings of herbicide molecules and organic cations, which are favored with the smaller cation, BTMA. BTMA preadsorbed on the clay

Removal of per- and polyfluoroalkyl substances (PFAS) from water using magnetic cetyltrimethylammonium bromide (CTAB)-modified pine bark

Abstract Per- and polyfluoroalkyl substances (PFAS) have gained global attention in recent years due to their adverse effect on environment and human health. In this study, a novel and cost-effective sorbent was developed utilizing forestry by-product pine bark and tested for the removal of PFAS compounds from both synthetic solutions and contaminated groundwater. The synthesis of the adsorbent included two steps: 1) loading of cetyltrimethylammonium bromide (CTAB) onto the pine bark and followed by 2) a simple coating of magnetite nanoparticles. The developed sorbent (MC-PB) exhibited 100 % perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) removal from synthetic solution (10 µg/L PFOA and PFOS) and enabled quick magnetic separation. A rapid removal of PFOA (> 80 %) by MC-PB was observed within 10 min from synthetic PFOA solution and the adsorption equilibrium was reached within 4 h, achieving > 90 % removal of PFOA (dosage 2 g/L, PFOA 10 mg/L, initial pH 4.2). The PFOA adsorption kinetics fitted well to an optimized pseudo-order model (R2=0.929). Intra-particle diffusion and Boyd models suggested that the adsorption process was not governed by pore diffusion. The maximum PFOA adsorption capacity was found to be 69 mg/g and the adsorption isotherm was best described by the Dual Mode Model (R2=0.950). The MC-PB demonstrated > 90 % PFOA and PFOS removal from contaminated groundwater. Furthermore, both short- and long-chain perfluorosulfonic acids and 6:2 fluorotelomer sulfonate were efficiently removed resulting in 83.9 % removal towards total PFAS (2 g/L dosage).Abstract Per- and polyfluoroalkyl substances (PFAS) have gained global attention in recent years due to their adverse effect on environment and human health. In this study, a novel and cost-effective sorbent was developed utilizing forestry by-product pine bark and tested for the removal of PFAS compounds from both synthetic solutions and contaminated groundwater. The synthesis of the adsorbent included two steps: 1) loading of cetyltrimethylammonium bromide (CTAB) onto the pine bark and followed by 2) a simple coating of magnetite nanoparticles. The developed sorbent (MC-PB) exhibited 100 % perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) removal from synthetic solution (10 µg/L PFOA and PFOS) and enabled quick magnetic separation. A rapid removal of PFOA (> 80 %) by MC-PB was observed within 10 min from synthetic PFOA solution and the adsorption equilibrium was reached within 4 h, achieving > 90 % removal of PFOA (dosage 2 g/L, PFOA 10 mg/L, initial pH 4.2). The PFOA adsorption kinetics fitted well to an optimized pseudo-order model (R2=0.929). Intra-particle diffusion and Boyd models suggested that the adsorption process was not governed by pore diffusion. The maximum PFOA adsorption capacity was found to be 69 mg/g and the adsorption isotherm was best described by the Dual Mode Model (R2=0.950). The MC-PB demonstrated > 90 % PFOA and PFOS removal from contaminated groundwater. Furthermore, both short- and long-chain perfluorosulfonic acids and 6:2 fluorotelomer sulfonate were efficiently removed resulting in 83.9 % removal towards total PFAS (2 g/L dosage)

new tailor made bio organoclays for the remediation of olive mill waste water

A systematic study aimed at obtaining new organoclays for the treatment of Olive Mill Waste water (OMW) has been performed. Several organoclays have been prepared by loading different amounts of the biocompatible surfactant Tween20 onto the K10 montmorillonite (MMT). Complementary kinetic and equilibrium studies on the adsorption of the Tween20 onto the MMT have been carried out and the characterization of the new tailor-made bio-materials has been performed by means of the XRD and FT-IR measurements. Finally the prepared bio-organoclays have been successfully applied for the OMW remediation and they proved to be highly effective in decreasing the organic content (OC) to an extent that depends on both the amount of loaded surfactant and the experimental protocols applied

Review on nanoparticles and nanostructured materials: History, sources, toxicity and regulations

Nanomaterials (NMs) have gained prominence in technological advancements due to their tunable physical, chemical and biological properties with enhanced performance over their bulk counterparts. NMs are categorized depending on their size, composition, shape, and origin. The ability to predict the unique properties of NMs increases the value of each classification. Due to increased growth of production of NMs and their industrial applications, issues relating to toxicity are inevitable. The aim of this review is to compare synthetic (engineered) and naturally occurring nanoparticles (NPs) and nanostructured materials (NSMs) to identify their nanoscale properties and to define the specific knowledge gaps related to the risk assessment of NPs and NSMs in the environment. The review presents an overview of the history and classifications of NMs and gives an overview of the various sources of NPs and NSMs, from natural to synthetic, and their toxic effects towards mammalian cells and tissue. Additionally, the types of toxic reactions associated with NPs and NSMs and the regulations implemented by different countries to reduce the associated risks are also discussed