Optimization of Carbon Dioxide and Valeric Acid Utilization for Polyhydroxyalkanoates Synthesis by Cupriavidus necator

The utilization of captured CO₂ as a part of the CO₂ capture and storage system to produce biopolymers could address current environmental issues such as global warming and depletion of resources. In this study, the effect of feeding strategies of CO₂ and valeric acid on cell growth and synthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] in Cupriavidus necator was investigated to determine the optimal conditions for microbial growth and biopolymer accumulation. Among the studied CO₂ concentrations (1–20 %), microbial growth and poly(3-hydroxybutyrate) accumulation were optimal at 1 % CO₂ using a gas mixture at H₂:O₂:N₂ = 7:1:91 % (v/v). When valeric acid was fed together with 1 % CO₂, (R)-3-hydroxyvalerate synthesis increased with increasing valeric acid concentration up to 0.1 %, but (R)-3-hydroxybutyrate synthesis was inhibited at >0.05 % valeric acid. Sequential addition of valeric acid (0.05 % at Day 0 followed by 0.025 % at Day 2) showed an increase in 3HV fraction without inhibitory effects on 3HB synthesis during 4 d accumulation period. The resulting P(3HB-co-3HV) with 17–32 mol  % of 3HV is likely to be biocompatible. The optimal concentrations and feeding strategies of CO₂ and valeric acid determined in this study for microbial P(3HB-co-3HV) synthesis can be used to produce biocompatible P(3HB-co-3HV).     

The Potential of Cleaner Fermentation Processes for Bioplastic Production: A Narrative Review of Polyhydroxyalkanoates (PHA) and Polylactic Acid (PLA)

Journal of Polymers and the Environment - Synthetic plastics generate major problems in landfills after their consumption for occupying high volumes and difficult the decomposition of other organic...     

Fiber from DDGS and Corn Grain as Alternative Fillers in Polymer Composites with High Density Polyethylene from Bio-based and Petroleum Sources

The steady increase in production of corn based ethanol fuel has dramatically increased the supply of its major co-product known as distiller’s dried grain with solubles (DDGS). Large amount of DDGS and corn flour are used as an animal feed. The elusieve process can separate DDGS or corn flour into two fractions: DDGS fraction with enhanced protein and oil content or corn flour fraction with high starch content, and hull fiber. This study investigated the feasibility of using fiber from DDGS and corn grain as alternative fillers to wood fiber in high density polyethylene (HDPE) composites made with two different sources of polymers. Two fiber loading rates of 30 and 50% were evaluated for fiber from DDGS, corn, and oak wood (control) to assess changes in various physical and mechanical properties of the composite materials. Two HDPE polymers, a bio-based HDPE made from sugarcane (Braskem), and a petroleum based HDPE (Marlex) were also compared as substrates. The biobased polymer composites with DDGS and corn fibers showed significantly lower water absorption than the Marlex composite samples. The Braskem composite with 30% DDGS fiber loading showed the highest impact resistance (80 J/m) among all the samples. The flexural properties showed no significant difference between the two HDPE composites.     

Tween 20 and Its Major Free Fatty Acids as Carbon Substrates for the Production of Polyhydroxyalkanoates in Pseudomonas aeruginosa ATCC 27853

The ability of Pseudomonas aeruginosa ATCC 27853 to grow and synthesize polyhydroxyalkanoates (PHAs) using Tween 20 as the sole carbon source was investigated. Tween 20 could support cell growth and PHA production. The polymer produced from Tween 20 was compared with those produced from its major free fatty acids components: lauric (C₁₂), myristic (C₁₄), and palmitic (C₁₆) acids. Gas-chromatographic analysis of methanolyzed samples and ¹³C-Nuclear Magnetic Resonance (NMR) showed that the PHAs obtained are composed of even carbon atoms 3-hydroxyalkanoates ranging from C₆ to C₁₄, with C₈ and C₁₀ as the predominant components. The nature of the carbon sources used had little influence on the composition, but was found to be important in determining the average molecular weight, shorter chain fatty acids yielding higher molecular weight products. Fast Atom Bombardment-Mass Spectrometry (FAB-MS) of partially pyrolyzed samples, coupled to statistical analysis, showed that these PHAs are random copolymers.     

Alternative strategies for energy recovery from municipal solid waste Part A: Mass and energy balances

This two-part paper assesses four strategies for energy recovery from municipal solid waste (MSW) by dedicated waste-to-energy (WTE) plants generating electricity through a steam cycle. The feedstock is the residue after materials recovery (MR), assumed to be 35% by weight of the collected MSW. In strategy 1, the MR residue is fed directly to a grate combustor. In strategy 2, the MR residue is first subjected to light mechanical treatment. In strategies 3 and 4, the MR residue is converted into RDF, which is combusted in a fluidized bed combustor. To examine the relevance of scale, we considered a small waste management system (WMS) serving 200,000 people and a large WMS serving 1,200,000 people. A variation of strategy 1 shows the potential of cogeneration with district heating. The assessment is carried out by a Life Cycle Analysis where the electricity generated by the WTE plant displaces electricity generated by fossil fuel-fired steam plants. Part A focuses on mass and energy balances, while Part B focuses on emissions and costs. Results show that treating the MR residue ahead of the WTE plant reduces energy recovery. The largest energy savings are achieved by combusting the MR residue "as is" in large scale plants; with cogeneration, primary energy savings can reach 2.5% of total societal energy use.     

从水溶液中分离回收醋酸方法的评述

评述了从水溶液中分离回收醋酸的普通精馏法、共沸精馏法、酯化法和溶剂萃取法，具体分析了各种方法 特点及适用范围。建议在工业上对较高浓度的醋酸用低沸点溶剂萃取－共沸精馏联合法，对低浓度醋酸溶液采用有机胺溶剂萃取法进行分离。     

Carbon emissions reduction strategies in Africa from improved waste management: A review

The paper summarises a literature review into waste management practices across Africa as part of a study to assess methods to reduce carbon emissions. Research shows that the average organic content for urban Municipal Solid Waste in Africa is around 56% and its degradation is a major contributor to greenhouse gas emissions. The paper concludes that the most practical and economic way to manage waste in the majority of urban communities in Africa and therefore reduce carbon emissions is to separate waste at collection points to remove dry recyclables by door to door collection, compost the remaining biogenic carbon waste in windrows, using the maturated compost as a substitute fertilizer and dispose the remaining fossil carbon waste in controlled landfills.     

Screening and Identification of Newly Isolated Basic Red 9-Degrading Bacteria from Textile Wastewater and Their Ability to Produce Medium-Co-Long-Chain-Length Polyhydroxyalkanoates

Journal of Polymers and the Environment - Newly isolated Basic Red 9-degrading bacteria were isolated from textile wastewater using a pretreatment method. Nine strains were isolated; however, only...     

Recent Industrial Applications of Lignin: A Sustainable Alternative to Nonrenewable Materials

Lignin represents a vastly under-utilized natural polymer co-generated during papermaking and biomass fractionation. Different types of lignin exist, and these differ with regard to isolation protocol and plant resource (i.e., wood type or agricultural harvesting residue). The incorporation of lignin into polymeric systems has been demonstrated, and this depends on solubility and reactivity characteristics. Several industrial utilization examples are presented for sulfur-free, water-insoluble lignins. These include materials for automotive brakes, wood panel products, biodispersants, polyurethane foams, and epoxy resins for printed circuit boards.     

Alternative strategies for energy recovery from municipal solid waste Part B: Emission and cost estimates

This two-part paper assesses four strategies for energy recovery from Municipal Solid Waste (MSW) by dedicated Waste-To-Energy (WTE) plants. In strategy 1, the residue of Material Recovery (MR) is fed directly to a grate combustor, while in strategy 2 the grate combustor comes downstream of light mechanical treatment. In strategies 3 and 4, the MR residue is converted into Refuse Derived Fuel (RDF), in a fluidized cumbuster bed. The results of Part A, devoted to mass and energy balances, clearly show that pre-treating the MR residue in order to increase the heating value of the feedstock fed to the WTE plant has marginal effects on the energy efficiency of the WTE plant. When considering the efficiency of the whole strategy of waste management, the energy balances show that the more thorough the pre-treatment, the smaller the amount of energy recovered per unit of MR residue. Starting from the heat/mass balances illustrated in Part A, Part B examines the environmental impacts and economics of the various strategies by means of a Life Cycle Assessment (LCA). Results show that treating the MR residues ahead of the WTE plant does not provide environmental or economic benefits. RDF production worsens almost all impact indicators because it reduces net electricity production and thus the displacement of power plant emissions; it also increases costs, because the benefits of improving the quality of the material fed to the WTE plant do not compensate the cost of such improvement.     

Natural Rubber-Based Pressure-Sensitive Adhesives: A Review

The purpose of this review is to describe the various aspects of pressure-sensitive adhesives prepared from natural rubber. Pressure-sensitive adhesives (PSAs) adhere instantaneously to a variety of surfaces upon application of slight pressure and can be obtained using different technologies. PSAs are materials that develop tack for low pressures and short contact times. There are number of factors affecting the adhesion property of natural rubber based pressure-sensitive adhesives. In this review, factors affecting adhesion property such as tack, peel and shear are examined in light of their relevance to adhesion in addition to measurement methods of each of the three major adhesion properties. This review paper covers the work being carried out from the last 20 years in the field of natural rubber based pressure sensitive adhesives.     

Starch-Based Materials Encapsulating Anthocyanins: A Review

Journal of Polymers and the Environment - Anthocyanins (ACNs) are natural pigments broadly used in the food industry due to their color, antioxidant, and antimicrobial properties, however, these...     

Active and Intelligent Films Made from Starchy Sources/Blackberry Pulp

Functional, active and intelligent films were prepared from biopolymeric matrices (plantain starch and pre-gelatinized plantain flour) with and without the addition of a natural filler (blackberry pulp) using the casting methodology. A thorough examination of the physicochemical, antioxidant and antimicrobial properties of the both the matrices used and the developed films was then carried out. The films developed from matrices incorporating the blackberry pulp were more amorphous, thicker, less sensitive to moisture, and with higher melting temperatures than the films made without this natural filler. The degree of substitution, average molecular weight and attenuated total reflectance Fourier transform infrared spectroscopy of the films made with blackberry pulp suggest that the starch chains were cross-linked. This is probably because the citric acid contained in the pulp functions as a cross-linking agent. Films with added blackberry pulp responded to changes in pH, i.e. were pH-sensitive, and also showed antimicrobial activity especially against Escherichia coli. In general, the addition of blackberry pulp improved the physicochemical and mechanical properties of the films developed due to cross-linking, as well as increasing their antioxidant activity.     

Methods Currently Used in Testing Microbiological Degradation and Deterioration of a Wide Range of Polymeric Materials with Various Degree of Degradability: A Review

Biodegradation of polymeric materials affect a wide range of industries, information on degradability can provide fundamental information facilitating design and life-time analysis of materials. Among the methods currently used in testing, traditional gravimetric and respirometric techniques are tailored to readily degradable polymeric materials mostly and polymer blends with biodegradable components, but they are not applicable to the new generation of engineering polymers which are relatively resistant to biodegradation. However, electrochemical impedance spectroscopy (EIS) has been tested for monitoring biodeterioration of high strength materials and the technique has very high sensitivity. A wide range of materials including electronic insulation polyimides, fiber-reinforced polymeric composites (FRPCs) and corrosion protective polyurethane coatings have been successfully measured under inoculation of degradative microorganisms using EIS. In addition, the mechanism of degradation of high strength polymers is mainly due to the presence of plasticizers in the polymer matrices. The information on various methods discussed in this review is intended to illustrate a suite of methods for those who are interested in testing biodeterioration of polymeric materials under different environmental conditions and in selecting appropriate techniques for specific applications.     

Degradation of Cellulose Acetate-Based Materials: A Review

Cellulose acetate polymer is used to make a variety of consumer products including textiles, plastic films, and cigarette filters. A review of degradation mechanisms, and the possible approaches to diminish the environmental persistence of these materials, will clarify the current and potential degradation rates of these products after disposal. Various studies have been conducted on the biodegradability of cellulose acetate, but no review has been compiled which includes biological, chemical, and photo chemical degradation mechanisms. Cellulose acetate is prepared by acetylating cellulose, the most abundant natural polymer. Cellulose is readily biodegraded by organisms that utilize cellulase enzymes, but due to the additional acetyl groups cellulose acetate requires the presence of esterases for the first step in biodegradation. Once partial deacetylation has been accomplished either by enzymes, or by partial chemical hydrolysis, the polymer’s cellulose backbone is readily biodegraded. Cellulose acetate is photo chemically degraded by UV wavelengths shorter than 280 nm, but has limited photo degradability in sunlight due to the lack of chromophores for absorbing ultraviolet light. Photo degradability can be significantly enhanced by the addition of titanium dioxide, which is used as a whitening agent in many consumer products. Photo degradation with TiO₂ causes surface pitting, thus increasing a material’s surface area which enhances biodegradation. The combination of both photo and biodegradation allows a synergy that enhances the overall degradation rate. The physical design of a consumer product can also facilitate enhanced degradation rate, since rates are highly influenced by the exposure to environmental conditions. The patent literature contains an abundance of ideas for designing consumer products that are less persistent in the outdoors environment, and this review will include insights into enhanced degradability designs.     

Influence of Carbon Sources on The Production and Characterization of The Exopolysaccharide (EPS) by Bacillus sphaericus 7055 Strain

In this study, EPS produced by five Bacillus spp. strains was determined. The only one strain (B. sphaericus 7055) was selected due to its high EPS production and it was investigated by growing this strain in LB broth medium containing various carbon sources. The highest EPS production of this strain was found in medium containing fructose. However, the effect of different concentrations of fructose and molasses on EPS production by the strain was studied. The maximum EPS yield of the strain 7055 was recorded with 2.5% (w/v) fructose, also the highest EPS production was found in 2.5% (w/v) molasses. The strain 7055 was found to contain (98.6%) galactose and (1.4%) glucuronic acid in control medium whereas the composition of the strain 7055 (2.5% (w/v) fructose) was found to be (99.9%) neutral sugar and (0.1%) Glucuronic acid while the strain 7055 (2.5% (w/v) molasses) was found to contain (65.9%), neutral sugars and (34.1%) glucuronic acid.     

Immobilization and Encapsulation of Contaminants Using Silica Treatments: A Review

The immobilization and encapsulation of contaminants using silica treatments is an emerging technology for the management of contaminated land. This article reviews the potential of silica treatments for the management of metals, hydrocarbons, and acid mine drainage at contaminated sites; and evaluates the effects of environmental conditions on silica treatment performance. The review demonstrates the potential of silica treatments for managing contaminated land; however, a paucity of research offers only a limited understanding of this technology. Further development of the technology will require additional research evaluating its long‐term performance under a range of environmental conditions. Field‐based experiments and studies investigating potential adverse effects of silica treatments are also necessary to demonstrate the safety, efficacy, and reliability of silica treatments. © 2013 Wiley Periodicals, Inc.     

Spatial GHG Inventory: Analysis of Uncertainty Sources. A Case Study for Ukraine

A geoinformation technology for creating spatially distributed greenhouse gas inventories based on a methodology provided by the Intergovernmental Panel on Climate Change and special software linking input data, inventory models, and a means for visualization are proposed. This technology opens up new possibilities for qualitative and quantitative spatially distributed presentations of inventory uncertainty at the regional level. Problems concerning uncertainty and verification of the distributed inventory are discussed. A Monte Carlo analysis of uncertainties in the energy sector at the regional level is performed, and a number of simulations concerning the effectiveness of uncertainty reduction in some regions are carried out. Uncertainties in activity data have a considerable influence on overall inventory uncertainty, for example, the inventory uncertainty in the energy sector declines from 3.2 to 2.0% when the uncertainty of energy-related statistical data on fuels combusted in the energy industries declines from 10 to 5%. Within the energy sector, the ‘energy industries’ subsector has the greatest impact on inventory uncertainty. The relative uncertainty in the energy sector inventory can be reduced from 2.19 to 1.47% if the uncertainty of specific statistical data on fuel consumption decreases from 10 to 5%. The ‘energy industries’ subsector has the greatest influence in the Donetsk oblast. Reducing the uncertainty of statistical data on electricity generation in just three regions – the Donetsk, Dnipropetrovsk, and Luhansk oblasts – from 7.5 to 4.0% results in a decline from 2.6 to 1.6% in the uncertainty in the national energy sector inventory.     

Curcumin- A Bio-based Precursor for Smart and Active Food Packaging Systems: A Review

Journal of Polymers and the Environment - The current scenario of global trends impacts the way in which food is consumed and packed, meaning that change is inevitable and just around the horizon...