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Bernats M.,Riga Technical University | Bernats M.,Bioenergetics and Biotechnology Competence Center | Juhna T.,Riga Technical University
Open Biotechnology Journal

Phenol is a major contaminant in the industrial water effluent, including pharmaceutical wastewaters. Although several physic-chemical methods for removal of phenol exist, they are of high cost, low efficiency, and generate toxic by-products. Thus, there is a need to develop technologies for biological removal of phenol from wastewater. In this study, the degradation of phenol in pharmaceutical wastewater by monoculture of white-rot fungi was studied. The degradation rate of total phenol in batch flasks by four fungal monocultures of Trametes versicolor, Phanerochaete chrysosporium, Gloeophyllum trabeum and Irpex lacteus in synthetic medium was compared. The results showed that white-rot fungus T.Versicolor was the most effective of the species. Further selection tests of optimal conditions of biomass concentration, pH and temperature were done, indicating that optimal conditions of degradation are at pH 5-6, temperature 25 °C, and biomass inoculum 10% (v/v). Under optimal conditions, total phenol was reduced by 93%, concentration of total phenol decreasing from 420±12 mg/l to 29±1 mg/l in seven days, with T.Versicolor specie. This study suggested that biological treatment with fungi may effectively be used as a pre-treatment stage for removal of phenol before polishing wastewater with conventional biological methods. © Bernats and Juhna. Source

Grigale-Sorocina Z.,Bioenergetics and Biotechnology Competence Center | Kalnins M.,Riga Technical University | Gross K.A.,Riga Technical University
IOP Conference Series: Materials Science and Engineering

Increased interest in the esthetical natural nail coatings have encouraged more in-depth studies particularly of UV curable coatings: their formation, processing, structure, characteristics and removing. Typical requirement for nail coatings is good adhesion, but preferably for the short time of functioning (usual 2-4 weeks). This study investigated the impact of four different monomers (tertiobutyl cyclohexyl acrylate (TBCHA), ethylene glycol dimethacrylate (EGDMA), tetrahydrofurfuryl acrylate (THFA), hydroxypropyl methacrylate (HPMA)) to viscosity of uncured mixture and degree of conversion, mechanical properties, surface gloss, micro hardness and adhesion loss for cured films. Specific coating application requires comparatively high coating flexibility and stability of deformation characteristics. This can be achieved with composition containing 30% of monomer TBCHA, what shows ultimate elongation ϵB = 0,23 - 0,24, modulus of elasticity E = 670-710 MPa and comparatively constant properties in 72 hours (ΔE = 1.3%, ΔϵB=6.0%). A composition with 40% of TBCHA shows the fastest coating destruction achieving adhesion loss within 3 min. © Published under licence by IOP Publishing Ltd. Source

Rozitis D.,Bioenergetics and Biotechnology Competence Center | Strade E.,Bioenergetics and Biotechnology Competence Center
Journal of Materials and Environmental Science

Efficiency of a biological wastewater treatment process depends on microbial diversity and their ability to degrade specific pollutants. The aim of this study was isolation and identification of predominant microorganisms associated with pharmaceutical wastewater pre-treatment process and evaluation of a chemical oxygen demand (COD) removal efficiency of each individual isolate. There were 65 microorganisms isolated from activated sludge of the JSC "Grindeks" industrial wastewater biological pre-treatment process and subsequently tested for COD reduction in pharmaceutical wastewater containing 2300-3500 mg/l of COD. Out of all isolates 9 bacteria, 5 yeasts and 3 filamentous fungi showed COD reduction. The highest COD reduction levels among all isolates were observed from filamentous fungi Fusarium udum (88.7%) and Fusarium solani (89.4%). The most effective bacterial strains were Aeromonas caviae and Sphingobacterium thalpophilum, with 78.1% and 75.9% COD removal, respectively. Rhodotorula mucilaginosa was the most effective yeast strain and achieved 76.6% COD reduction. Source

Grigale-Sorocina Z.,Riga Technical University | Kalnins M.,Riga Technical University | Simanovska J.,Bioenergetics and Biotechnology Competence Center | Vindedze E.,Bioenergetics and Biotechnology Competence Center | And 2 more authors.
Proceedings of the Estonian Academy of Sciences

Thin UV curable coating systems is an important research field from the industrial perspective due to the improved environmental profile and wide varieties of characteristics. When used for short-term applications as coatings on natural nail for esthetical and medical reasons, the system may be manipulated to attain various properties, either desired or required by the manufacturer e.g. ensuring both excellent long-term properties (deformability, toughness, and good adhesion) and short-term properties (ability to be destroyed quickly after use). Performance of thin UV curable urethane acrylate composite coatings was investigated depending on the content of the additive. Nitrocellulose (NC), cellulose acetate butyrate (CAB), sucrose benzoate (SB), and silica were evaluated to determine their influence on unreacted composite characteristics (viscosity, suspension pigment stability) and reacted film characteristics (ultimate strength, elongation at break, surface gloss, surface micro hardness, and film adhesion loss). According to the tests performed all additives increase the modulus of elasticity. CAB and NC increase the elongation at break values, and strongly increase the uncured gel viscosity, what makes it inconvenient for application. © 2015, Estonian Academy Publishers. All rights reserved. Source

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