A liquid emulsion membrane process for the separation of amino acids

The method of using liquid emulsion membranes featuring the cation carrier D2EHPA [di-(2-ethylhexyl) phosphoric acid] for the separation of L-phenylalanine is examined. Results from experiments performed under various conditions are discussed and an optimal condition for separation is determined. The selectivity of the liquid emulsion membrane system is discussed. The effects of impurities such as sodium chloride, glucose, lactic acid, and L-tryptophan on the transport of L-phenylalanine are evaluated. It is shown that the liquid emulsion membrane system is a potential operation not only to separate L-phenylalanine but also concentrate it with great efficiency.     

Performance evaluation of various bioreactors for the removal of Cr(VI) and organic matter from industrial effluent

Performances of various bioreactors under different operating conditions were evaluated with respect to hexavalent chromium (Cr(VI)) reduction and COD removal. Continuous reactor studies were carried out with (i) aerobic suspended growth system, (ii) aerobic attached growth system, and (iii) anoxic attached growth system, using both synthetic and actual industrial wastewater. Arthrobacter rhombi-RE (MTCC7048), a Cr(VI) reducing strain enriched and isolated from chromium contaminated soil, was used in all the bioreactors for Cr(VI) biotransformation and COD removal. Aerobic and anoxic batch experiments were conducted to evaluate the bio-kinetic parameters. The bio-kinetic parameters for aerobic system were: μ_max = 2.34/d, K_s = 190 mg/L (as COD), K_i = 3.8 mg/L of Cr(VI), and Y_T = 0.377. These parameters for anoxic conditions were: μ_max = 0.57/d, K_s = 710 mg/L (as COD), K_i = 8.77 mg/L of Cr(VI), and Y_T = 0.13. Aerobic attached growth system, operated at a hydraulic retention time (HRT) of 24 h and an organic loading rate (OLR) of 3 kg/m³/d, performed better than aerobic suspended and the anoxic attached growth systems operated under identical conditions, while treating synthetic wastewater as well as industrial effluent.     

A study on enzymatic reaction using a liquid emulsion membrane technique

An enzymatic reaction using a liquid emulsion membrane technique was studied to investigate the effects of some experimental variables on the stability of liquid membrane, enzyme deactivation, and transport of substrates and products. The hydrolysis of L-phenylalanine methyl ester by alpha-chymotrypsin was selected as a model reaction system. First, a transport mechanism for the substrates and products across the membrane was qualitatively identified. Second, it was found that the pH of the internal phase was one of the most important variables to determine the enzyme activity in a liquid membrane. Third, the effect of membrane phase which consists of surfactant, carrier, and organic solvent on the emulsion stability was investigated. It was found that the properties of the organic solvents greatly affect the emulsion stability. For an optimum condition, it was possible to reuse the emulsion which consists of membrane phase and internal phase without further separation. It was finally concluded that the enzyme in a liquid membrane retained 60% of its native activity in spite of vigorous mixing during the emulsification step.     

Enhanced bioremediation efficiency of denim industrial effluent using bacterial biofilm onto polyurethane matrix (review)

This paper presents the review of the effects of bioremediation on the denim textile effluent using adapted bacterial cells immobilized on polyurethane foam. It further examines the various methods used in the biodecolorization of the industrial wastewater including the action of oxidative enzymes. Bacterial biofilms have great potential for the sustainable production of enzymes because of their high resistant, inherent characteristic of self immobilization and long term activity. It was also found that bacterial biofilm is widely used to treat textile wastewater because of the advantage derived from its ability to withstand under extreme conditions with their action of oxidoreductase enzymes.     

A comprehensive review on application of bioreactor for industrial wastewater treatment

In the recent past, wastewater treatment processes performed a pivotal role in accordance with maintaining the sustainable environment and health of mankind at a proper hygiene level. It has been proved indispensable by government regulations throughout the world on account of the importance of preserving freshwater bodies. Human activities, predominantly from industrial sectors, generate an immeasurable amount of industrial wastewater loaded with toxic chemicals, which not only cause dreadful environmental problems, but also leave harmful impacts on public health. Hence, industrial wastewater effluent must be treated before being released into the environment to restrain the problems related to industrial wastewater discharged to the environment. Nowadays, biological wastewater treatment methods have been considered an excellent approach for industrial wastewater treatment process because of their cost-effectiveness in the treatment, high efficiency and their potential to counteract the drawbacks of conventional wastewater treatment methods. Recently, the treatment of industrial effluent through bioreactor has been proved as one of the best methods from the presently available methods. Reactors are the principal part of any biotechnology-based method for microbial or enzymatic biodegradation, biotransformation and bioremediation. This review aims to explore and compile the assessment of the most appropriate reactors such as packed bed reactor, membrane bioreactor, rotating biological contactor, up-flow anaerobic sludge blanket reactor, photobioreactor, biological fluidized bed reactor and continuous stirred tank bioreactor that are extensively used for distinct industrial wastewater treatment.     

A micro-immuno supported liquid membrane assay (mu-ISLMA)

A chemiluminescent (CL) based micro-immuno supported liquid membrane assay (mu-ISLMA) has been developed that enables clean up, enrichment and detection of simazine in a single miniaturised cartridge system. The mu-ISLM cartridge contains a supported liquid membrane (SLM) sandwiched between a donor and an acceptor plate (channel volumes 1.65 microL), the latter being covered by a thin layer of gold on to which anti-simazine antibodies were covalently immobilised via a self assembled monolayer (SAM) of either dithiobis(11-aminoundecane, hydrochloride) (DTAU) or beta-mercaptoethylamine (beta-MEA). The mu-ISLMA based on DTAU was characterised by both a high apparent extraction efficiency (E(app) = 136%) and high apparent enrichment factor (E(e)(app) = 544), which resulted in a very high sensitivity for simazine (LOD = 0.1 ng L(-1)). The paper discusses the influence of the different SAMs and three different anti-simazine-antibody preparations (polyclonal, affinity purified polyclonal and monoclonal) on the extraction parameters and assay sensitivity. The influence of the sample matrix (e.g. mineral water, orange juice and milk) on the simazine mu-ISLMA was also investigated.     

Development of a new reversed micelle liquid emulsion membrane for protein extraction

A new type of liquid emulsion membrane containing reversed micelles for protein extraction is introduced. A three-step extraction mechanism is proposed including solubilization, transportation, and release of the protein. The surfactants Span80 and sodium di(2-ethylhexyl)sulfosuccinate (AOT) are used to stabilize the membrane phase and to build up the reversed micelles, respectively. alpha-Chymotrypsin was used as the model protein. The condition in the internal phase inhibits the solubilization process of the already extracted protein back into reversed micelles. Concerning the solubilization, we studied the influence of the AOT concentration in the membrane phase and the ionic strength in the external phase. The extraction rate increases with higher AOT concentration and decreases with higher ionic strength. Using NaCl in the external phase led to better extraction results than using KCl. Maximum extraction results of 98% into the membrane phase and 65% into the internal phase were obtained. This condition retained 60% of the enzyme's activity. The concentration of KCl in the internal phase does not affect the solubilization rate but the release into the internal phase. By this way the ionic strength in the internal phase is used as the driving force for the protein release. The solubilization process is much faster than the diffusion and the releasing process, as found by variation of the extraction time. The influence of the operating conditions on the membrane swelling is also discussed. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 267-273, 1997.     

Fouling in reverse osmosis (RO) membrane in water recovery from secondary effluent: a review

Reverse osmosis (RO) is the most preferable process for water recovery from secondary effluent (SE) because of its higher rejection of impurities with lower associated cost and higher quality of product. Fouling still is a major challenge during the water recovery due to higher contaminant loadings in SE and high rejection capability of this membrane. The presence of suspended solids, colloidal and organic matters, and high level of biological activities in SE further elevate fouling potentiality. This review was performed to identify major foulants causing hindrance in sustainable application of reverse osmosis and to present available pre-treatment options for these foulants. There are four fouling types present in RO namely; bio-fouling, inorganic/scaling, organic, and particulate fouling. Among them; bio-fouling is less understood but dominant since the pre-treatment options are not well developed. Other fouling mechanisms have been overcome by well developed pre-treatments. The major foulants for RO are dissolved and macromolecular organic substances, sparingly soluble inorganic compounds, colloidal and suspended particles, and micro-organisms. Some of these potential fouling water quality parameters (PFWQPs) are interrelated with each others such as electrical conductivity is a surrogate measure of total dissolved solids with established stable relationship. Most of these PFWQPs such as total suspended solids, turbidity, chemical oxygen demand can be removed by conventional pre-treatment; some such as colloidal particles and micro-organisms by modern options and even others such as endocrine disrupting compounds, pharmaceutical and personal care products are still challenging for current pre-treatments. These foulants need to be identified properly to integrate appropriate pre-treatments for minimizing fouling potentiality to increase water recovery at minimal costs.     

Utility of field-based artificial streams for assessing effluent effects on riverine ecosystems

Experimentation using field-based artificial streams provides a promising, complimentary approach to biomonitoring assessments because artificial streams provide control over relevant environmental variables and true replication of treatments. We have used large and small artificial stream systems, based in the field, to examine the effect of treated bleached kraft pulp mill effluent (BKME) on the benthos of three large rivers in western Canada. Under natural regimes of temperature, water chemistry, and insolation, these artificial streams provide current velocities and substrata to food chains or food webs that are representative of those in the study river. With these tools we have shown that BKME stimulated mayfly growth in the Thompson River above that which could be accounted for by fertilization of their algal food supply. In contrast, moulting frequency was inhibited at high BKME concentrations. Results from artificial streams also indicate that increased algal biomass and abundances of benthic communities downstream of BKME outfalls were induced by nutrient enrichment from the effluent. BKME treatments did not change diatom species richness in the Fraser River, or diatom species diversity in either the Athabasca or Fraser Rivers. Artificial streams provide a means of understanding the mechanisms of stressor effects over a continuum ranging from single stressor effects on specific taxa to the effects of multiple stressors on communities and ecosystems. Because riverside deployment provides environmental realism within a replicated experimental design, this approach can (i) address questions that cannot be examined using laboratory tests or field observations, (ii) improve our mechanistic understanding of stressor effects on riverine ecosystems, and (iii) can contribute directly to the development, parameterization, and testing of models for predicting ecosystem-level responses.     

Effects of stream restoration and wastewater treatment plant effluent on fish communities in urban streams

1. Fish community characteristics, resource availability and resource use were assessed in three headwater urban streams in Piedmont North Carolina, U.S.A. Three site types were examined on each stream; two urban (restored and unrestored) and a forested site downstream of urbanisation, which was impacted by effluent from a wastewater treatment plant (WWTP). Stream basal resources, aquatic macroinvertebrates, terrestrial macroinvertebrates and fish were collected at each site. 2. The WWTPs affected isotope signatures in the biota. Basal resource, aquatic macroinvertebrate and fish δ¹⁵N showed significant enrichments in the downstream sites, although δ¹³C signatures were not greatly influenced by the WWTP. Fish were clearly deriving a significant part of their nutrition from sewage effluent‐derived sources. There was a trend towards lower richness and abundance of fish at sewage‐influenced sites compared with urban restored sites, although the difference was not significant. 3. Restored stream sites had significantly higher fish richness and a trend towards greater abundance compared with unrestored sites. Although significant differences did not exist between urban restored and unrestored areas for aquatic and terrestrial macroinvertebrate abundances and biotic indices of stream health, there appeared to be a trend towards improvements in restored sites for these parameters. Additional surveys of these sites on a regular basis, along with maintenance of restored features are vital to understanding and maximising restoration effectiveness. 4. A pattern of enriched δ¹³C in fish in restored and unrestored streams in conjunction with enriched δ¹³C of terrestrial invertebrates at these sites suggests that these terrestrial subsidies are important to the fish, a conclusion also supported by isotope cross plots. Furthermore, enriched δ¹³C observed for terrestrial invertebrates is consistent with some utilisation of the invasive C4 plants that occur in the urban riparian areas.     

Use of bioassay-based whole effluent toxicity (WET) tests to predict benthic community response to a complex industrial effluent

Whole effluent toxicity (WET) tests are a usefulmonitoring tool because they provide a rapid andreplicable measure of the potential ecotoxicologicaleffect of effluents. Although WET tests have beenincorporated into toxicity-based effluent limits toprotect receiving systems from adverse effects, fewstudies have attempted to quantitativelyfield-validate laboratory-derived toxicity thresholds.In this study, we examine the ability of WET tests topredict response thresholds of an invertebratecommunity to a paper mill effluent discharged into theNicolet-SW River, Québec, Canada. We quantifiedinvertebrate community structure and density in theriver and detrended for the effects ofphysical/chemical variables. This allowed examinationof direct correlation between invertebrate communitystructure and effluent concentration. There was asignificant decrease in taxonomic richness at aneffluent concentration of 16%, but significantchanges in the density of invertebrates occurredbetween 0% and 2% effluent. This suggests thatalthough most taxa returned to the river downstream ofthe effluent, they did so at lower densities.Calculated field thresholds were compared tolaboratory thresholds for the effluent using chronicWET tests with algae, cladocerans and fish. The WETtests produced a mean MATC of 3.6%. Thus, standardWET tests overestimated response thresholds of theinvertebrate community in the receiving environmentand impacts were observed in areas where no impact wasexpected.     

Release of treated effluent into streams: A global review of ecological impacts with a consideration of its potential use for environmental flows

1. Worldwide, the addition of treated wastewater (i.e. effluent) to streams is becoming more common as urban populations grow and developing countries increase their use of wastewater treatment plants. Release of treated effluent can impair water quality and ecological communities, but also could help restore flow and maintain aquatic habitat in water-stressed regions. To assess this range of potential outcomes, we conducted a global review of studies from effluent-fed streams to examine the impacts of effluent on water quality and aquatic and riparian biota.
2. We identified 147 quantitative studies of effluent-fed streams, most of which were from the U.S.A. and Europe. Over 85% of the studies identified water quality as a primary study focus, including basic physical and chemical parameters, as well as trace organic contaminants. Nearly 60% of the studies had at least some focus on aquatic or riparian biota, primarily fish, aquatic invertebrates, and basal resources (e.g. algae).
3. Effluent inputs generally impaired water quality near discharge points, mainly through increased water temperature, nutrients, and concentrations of trace organic contaminants, but also via decreased dissolved oxygen levels. The majority of ecological studies found that basal resources, aquatic invertebrates, and fish were negatively affected in a variety of ways (e.g. biodiversity losses, replacement of sensitive with tolerant species). However, several studies showed the importance of effluent in providing environmental flows to streams that had been dewatered by anthropogenic water withdrawals, especially in semi-arid and arid regions.
4. Knowledge gaps identified include the abiotic impacts of effluent, such as changes in channel morphology and hydrology (e.g. how nutrient-rich and warmer effluent affects infiltration rates or interactions with groundwater), the effects of effluent on plants and vertebrates (e.g. amphibians, birds), and the impact of effluent-induced perennialisation on naturally intermittent or ephemeral streams.
5. Although effluent-fed streams often exhibit signs of ecological impairment, there is great potential for these systems to serve as refuges of aquatic biodiversity and corridors of ecological connectivity when wastewater treatment standards are high, especially in semi-arid and arid regions where natural streams have been dewatered.

     

Recent trends in fungal laccase for various industrial applications: An eco-friendly approach - A review

The aim of this review is to determine the trends of state-of-art of laccase sources, properties, structure and recent application of fungal laccase in various fields. Laccases are biotechnologically important multi copper proteins that have broad substrate specificity towards aromatic and non-aromatic compounds. Fungi are the major laccase producers especially ascomycetes, deuteromycetes and basidiomycetes, and laccases have an average molecular weight between 50 and 130 kDa. Fungal laccases are used in biotechnological applications for preparation of anticancerous and anti-oxidant hormonal drugs, stabilization of food products, and laccase application is also extended to preparation of biosensors, DNA labeling, immunochemical assay, bioorganic compound synthesis etc. The environmental application of laccase is for biodegradation of dyes, phenols and pesticides, and the mechanism of degradation has been briefly explained. Analysis of the biodegraded dye sample by FT-IR and Mass (ESI)-spectrum has been discussed in a detailed manner. Modeling kinetics has been discussed with respect to degradation of wastes in order to understand the factors involved in the degradation process.     

Reverse micelles‐mediated transport of lipase in liquid emulsion membrane for downstream processing

This work deals with the downstream processing of lipase (EC 3.1.1.3, from Aspergillus niger) using liquid emulsion membrane (LEM) containing reverse micelles for the first time. The membrane phase consisted of surfactants [cetyltrimethylammonium bromide (CTAB) and Span 80] and cosolvents (isooctane and paraffin light oil). The various process parameters for the extraction of lipase from aqueous feed were optimized to maximize activity recovery and purification fold. The mechanism of lipase transport through LEM consisted of three steps namely solubilization of lipase in reverse micelles, transportation of reverse micelles loaded with lipase through the liquid membrane, and release of the lipase into internal aqueous phase. The results showed that the optimum conditions for activity recovery (78.6%) and purification (3.14‐fold) were feed phase ionic strength 0.10 M NaCl and pH 9.0, surfactants concentration (Span 80 0.18 M and CTAB 0.1 M), volume ratio of organic phase to internal aqueous phase 0.9, ratio of membrane emulsion to feed volume 1.0, internal aqueous phase concentration 1.0 M KCl and pH 7.0, stirring speed 450 rpm, and contact time 15 min. This work indicated the feasibility of LEM for the downstream processing of lipase. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012     

Influence of various factors on upper lethal temperature (review)

The influence of various factors on the upper lethal temperature (ULT) for the vital functions of freshwater fishes was investigated. The methods used for determining the lethal and sublethal temperatures in freshwater fishes were characterized. It was indicated that the acclimation temperature, heating rate, season, age of animals, time of day, and other factors significantly change the ULTs.     

Development of anaerobic digestion methods for palm oil mill effluent (POME) treatment

Palm oil mill effluent (POME) is a highly polluting wastewater that pollutes the environment if discharged directly due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD) concentration. Anaerobic digestion has been widely used for POME treatment with large emphasis placed on capturing the methane gas released as a product of this biodegradation treatment method. The anaerobic digestion method is recognized as a clean development mechanism (CDM) under the Kyoto protocol. Certified emission reduction (CER) can be obtained by using methane gas as a renewable energy. This review aims to discuss the various anaerobic treatments of POME and factors that influence the operation of anaerobic treatment. The POME treatment at both mesophilic and thermophilic temperature ranges are also analyzed.     

Comparison of microporous and nonporous membrane bioreactor systems for the treatment of BTEX in vapor streams

Increased regulatory constraints on industrial releases of atmospheric volatile organic compounds (VOCs) have resulted in an interest in using biofilters, bioscrubbers and air/liquid membranes for treatment of vapor phase waste streams. In this report, we describe the comparison of the use of two fundamentally different types of membrane module systems that allow the rapid diffusion of vapor phase aromatics and oxygen to an active biofilm for subsequent biodegradation. One system used a commercial membrane module containing microporous polypropylene fibers while the other used a nonporous silicone tubing membrane module for the delivery of substrate (a mixture of benzene, ethylbenzene, toluene, and xylenes [BTEX]) and electron acceptor (O₂). Tests of the systems under similar conditions with BTEX in the vapor feed stream showed significant performance advantages for the silicone membrane system. The average surface-area-based BTEX removal rate for the microporous membrane system over 500 h of operation was 7.88 μg h⁻¹ cm⁻² while the rate for the silicone membrane system was 23.87 μg h⁻¹ cm⁻². The percentages of BTEX removal were also consistently better in the silicone membrane system versus the microporous system. Part of the performance problem associated with the microporous membrane system appeared to be internal water condensation and possible plugging of the pores with biomass over time that could not be resolved with vapor phase backflushing. Journal of Industrial Microbiology & Biotechnology (2002) 28, 245–251 DOI: 10.1038/sj/jim/7000235 Received 17 August 2001/ Accepted in revised form 03 December 2001     

Studies on the modeling and simulation of a sequential bienzymatic reaction system immobilized in emulsion liquid membrane

Experiments have been carried out to study the reaction engineering behavior of the liquid membrane-encapsulated, sequential bienzymatic reaction system, n 2n glucose. A dynamic mathematical model, free from adjustable parameters, has been developed taking into account peri-emulsion mass transfer, intra-emulsion diffusion, membrane-related mass transfer limitations and substrate and product inhibitions. A finite difference-based, user-friendly software has been developed to solve the model equations. Experimental data satisfactorily correlate with the model. While it is understood that study of sequential bienzymatic reaction system immobilized in emulsion liquid is essential for their industrial exploitation, reaction engineering behavior of such a system in presence of both substrate and product inhibitions has not yet been reported in the literature. Therefore, the model predictions of the present investigations are expected to pave the way for scale-up and design of industrial bioreactors in this field.     

国内外产业共生网络研究比较述评

产业共生网络是指基于物质及能量交换以及知识及基础设施共享而形成的在不同产业主体之间的合作共赢网络,是产业转型升级的重要保障。作为产业共生的运作方式,产业共生网络的研究国外从20世纪90年代开始从概念到实例就展开了一系列探讨,国内自2002年也开始在网络结构等方面开展相关研究。尤其在2008年以后,产业共生网络的研究方向不断拓宽,研究成果丰富多样。为明晰国内外产业共生网络研究的发展态势,促进产业共生网络理论体系的发展并使其得到有效应用。本文从共生网络内涵、结构、功能及评价、演化、管理调控等方面比较分析了国内外产业共生网络的研究进展,并对产业共生网络的发展前景做了展望。未来产业共生网络研究在不同尺度的比较及推演、数据信息平台的搭建以及产业共生网络演化模拟及管理调控的耦合等方面需重点关注。     

Development of a supported emulsion liquid membrane system for propionic acid separation in a microgravity environment

Perstractive fermentation is a good way to increase the productivity of bioreactors. UsingPropionibacteria as the model system, the feasibility of using supported emulsion liquid membrane (SELM) for perstractive fermentation is assessed in this study. Five industrial solvents were considered as the solvent for preparing the SELM. The more polar a solvent is, the higher the partition coefficient. However, toxicity of a solvent also increases with its polarity. CO-1055 (industrial decanol/octanol blend) has the highest partition coefficient toward propionic acid among the solvents that has no molecular toxicity towardPropionibacteria. A preliminary extraction study was conducted using tetradecane as solvent in a hydrophobic hollow fiber contactor. The result confirmed that SELM eliminates the equilibrium limitation of conventional liquid-liquid extraction, and allows the use of a non-toxic solvent with low partition coefficient.