Current Environmental Engineering (v.1, #3)
Environmental Stress Tolerance Engineering by Modification of Cell Surface and Transcription Factor in Saccharomyces cerevisiae by Atsushi Satomura, Kouichi Kuroda, Mitsuyoshi Ueda (149-156).
In bioindustrial processes, organisms are subjected to a variety of stresses such as heavy metal ions, organic solvents, pH and high temperature. These stresses diminish or abolish their biological activities and cell growth, resulting in reduced efficiency of bioproduction. To maintain high bioproduction rates, stress-tolerant organisms that can grow and produce useful materials under stressful conditions are required. Recent studies have demonstrated that cell surface engineering and modification of transcription factors can improve the stress tolerance of organisms, especially the yeast Saccharomyces cerevisiae. The cell surface is in direct contact with the external environment and plays an essential role in stress responses. Therefore, artificial modification of the cell surface is an attractive way to improve tolerance against environmental stresses. In addition, transcription factors activate genes involved in a wide variety of stress response functions, including signal transduction, transcriptional control, transportation, and scavenging of toxic compounds. Mutations in transcription factors likely cause dynamic changes in the cellular system and can greatly improve stress tolerance. In this review, we summarize recent studies demonstrating improvement of tolerance to heavy metal ions, acid, organic solvents, and heat by modification of the cell surface and transcription factors of S. cerevisiae.
Wastewater Treatment in a Touristic Locality with a Plant Based on Moving Bed Biofilm Reactors (MBBR) by Luigi Falletti, Tiziano Battistini, Massimo Navarri (157-161).
The wastewater treatment plant of Sanremo, an Italian touristic locality, is dimensioned for 50,000 person equivalent (p.e.) during winter and 130,000 p.e. during summer. The plant is made of primary treatments, a biological section based on a three-stage moving bed biofilm reactor (MBBR), clariflocculation and flotation, phosphorus precipitation, secondary settling and disinfection. This is one of the biggest Italian plants based on MBBR. During the period of study, the plant removed 89-92% of COD, 94-96% of BOD and 72-80% of TKN; total nitrogen removal efficiency was only 14% since all MBBR tanks were aerated. Specific energy consumption was 4.02 kWhkgBOD-1 in winter and 2.78 kWhkgBOD -1 in summer; these values were affected by the consumption due to forced aeration, since the plant is located in a cave underground. Specific sludge production was 0.36-0.43 kgSSkgCOD -1. These results confirm that plants based on MBBR and dissolved air flotation are suitable and compact solutions for wastewater treatment also in touristic areas.
Treatment of Textile Dye Containing Effluents by Sumathi Suresh (162-184).
Textile mill discharges contain total dissolved solids (TDS), suspended solids (SS), complex dyes, odor, and total Kjeldahl nitrogen, bleaching chemicals and an array of pollutants that exert biological oxygen demand (BOD) and chemical oxygen demand (COD). In addition, salts, surfactants, heavy metals and mineral oils are also present in these wastewaters. The presence of color in wastewaters is due to the discharge of unfixed dyes which after hydrolysis are incapable of reacting with the fabrics. Discharge of untreated textile mill effluents is known to cause adverse environmental impacts. Therefore, it is mandatory to treat such wastewaters for the protection of environment and ecosystems. Textile dyeing wastewaters are usually treated to reduce conventional pollution loads such as BOD, COD, SS etc. However, specific pollutants such as dyes, heavy metals and electrolytes are not easily removed by conventional waste treatment methods. This review article provides updated description and analyses of physical, chemical and biological methods that have been used for the removal and degradation of textile dyes. However, each method presents disadvantages and thus there is no suitable method for the removal of dyes from textile dyeing effluents. Hybrid treatment schemes which carefully integrate appropriate physical, chemical and biological decolorization methods for specific industrial discharges are required for the successful removal of dyes. Selected methods should meet the following criteria for effective field scale applications: (a) non-specific with respect to various types of dyes and (b) result in complete elimination of dyes and (c) cost effective and rapid.
Pre-Concentration of Cs-137 Through Sorption: Low Level Analysis in Seawater by Abdul Ghaffar, Azhar Mashiattullah, Nadeem Yaqoob (185-190).
Comparative studies for the sorption of Cs-137 on silica coated potassium copper hexacyanoferrate and potassium cobalt hexacyanoferrate materials and an efficient method was optimized for its maximum sorption. The column sorption method was applied by packing synthesized material in specifically designed columns and low level/fallout level Cs-137 was sorbed on it from 2-4 L seawater sample (0.237 Bq/L). Higher sorption of Cs-137 was achieved on silica coated potassium copper ferrocyanate by optimizing the physical conditions at pH 8. Sorption potential of copper ferrocyanate was higher as compared to cobalt ferrocyanate under same optimized conditions. The developed method was, in field, applied for seawater sample collected from Arabian Sea, near the outfall of Karachi Nuclear Power Plant (KANUPP, Pakistan) by pumping 2-4L of seawater through synthesized material packed in columns. The results suggested that developed method was much precise and accurate as compared to conventional method.
Adsorption of Hexavalent Chromium Ion from Aqueous Solutions on Psyllium Mucilage and Cross-Linked Psyllium Mucilage Beads by Deepti Goyal, Anuradha Mishra (191-198).
In this paper, the adsorption of Cr(VI) by a natural polysaccharide, psyllium mucilage has been reported by conducting batch-type experiments at 37°C. Psyllium mucilage beads (PPB) were cross-linked with glutaraldehyde (GLA) to improve the chemical resistance and mechanical properties of beads. PPB and crosslinked (PPB-GLA) were characterized by FTIR (Fourier-Transform Infrared Spectroscopy) and SEM (Scanning Electron Microscopy). The adsorption rate and capacity of both adsorbents, PPB and PPB-GLA were measured. Adsorption experiments using AAS (Atomic Absorption Spectroscopy) were done at varying concentrations of hexavalent chromium (Cr(VI)), amount of PPB and PPB-GLA, time and pH. Adsorption of Cr(VI) was highly dependent on pH of the medium. One gram of PPB-GLA adsorbed 456 mg of chromium at pH 3. Cr(VI) adsorption has also been confirmed by EDAX (Energy Dispersion Analysis by X-ray) and DRUV (Diffuse reflectance UV-VIS) analysis. Equilibrium data correlated with the Langmuir model and kinetic experimental data fitted with the second-order kinetics.
Thermal Degradation of Single and Blended Amines for CO2 Capture Process by Nabil El Hadri, Hessa Mohammed Al Shehhi, Dang Viet Quang, Mohammad Abu-Zahra (199-206).
Thermal degradation of aqueous amine solutions of monoethanolamine (MEA) 30 wt% and 50 wt%, piperazine (Pz) 30 wt% and their blend (MEA 10 wt%/20 wt% Pz) with CO2 have been studied at 140C. A lab-scale experiment was performed in order to study the thermal degradation at the stripper operating conditions in post-combustion process. Experiments were done at different conditions (amine concentration, time exposure) and a quantification of the degradation products was obtained in order to understand the different impact of these parameters. Thermal degradation products were identified by gas chromatography - flame ionized detector (GC-FID). It has been shown that Pz is more stable against thermal degradation in comparison with MEA.
Agroecosystem Development of Industrial Fermentation Waste - Suppressive Effects of Beer Yeast Cell Wall Extract on Plant Diseases by Malek Marian, Kiriko Ogawa, Yui Yoshikawa, Satoko Takasaki, Atsushi Usami, Masafumi Shimizu, Mitsuo Miyazawa, Mitsuro Hyakumachi (207-211).
This paper demonstrates the ability of beer yeast cell wall extract (BYCWE) in suppressing various fungal and bacterial plant diseases. Root treatment with BYCWE suppressed Fusarium wilt of spinach, bacterial speck disease of Arabidopsis and cucumber anthracnose. Leaf and root extracts from BYCWE-treated spinach significantly reduced (Fusarium wilt) pathogen proliferation. Furthermore, BYCWE treatment induced the expression of defense related genes in Arabidopsis resulting from the activation of two pathways; salicylic acid (SA) and jasmonic acid (JA) /ethylene (ET) signaling pathway. As, BYCWE does not show any antimicrobial activity we propose that induction of systemic resistance acts as a mechanism of suppression against Fusarium wilt of spinach, bacterial speck of Arabidopsis and cucumber anthracnose. These results imply that the industrial fermentation waste of beer yeast cell may be utilized as a source of suppressive effects on various fungal and plant diseases.
Acknowledgements to the Reviewers: (212-212).