Removal of an anionic dye (Acid Blue 92) by coagulation–flocculation using chitosan

Chitosan (a biopolymer) is an aminopolysaccharide that can be used for the treatment of colored solutions by coagulation–flocculation (as an alternative to more conventional processes such as sorption). Acid Blue 92 (a sulfonic dye) was selected as a model dye for verifying chitosan's ability to treat textile wastewater. A preliminary experiment demonstrated that chitosan was more efficient at color removal in tap water than in demineralized water, and that a substantially lower concentration of chitosan could be used with tap water. Dye removal reached up to 99% under optimum concentration; i.e., in terms of the acidic solutions and the stoichiometric ratio between the amine groups of the biopolymer and the sulfonic groups in the dye. The flocs were recovered and the dye was efficiently removed using alkaline solutions (0.001–1 M NaOH solutions) and the biopolymer, re-dissolved in acetic acid solution, was reused in a further treatment cycle.     

The whole relationship between environmental variables and firm performance: Competitive advantage and firm resources as mediator variables

The examination of the possible direct link between environmental protection and firm performance in the literature has generally produced mixed results. The present paper contributes to the literature by using the resource-based view as a mediating process in this relationship. The study specifically tests whether or not the resource-based view of the firm mediates the positive relationships of proactive environmental management and improved environmental performance with competitive advantage, which also has consequences for financial performance. We also check the possible link between the adoption of a pioneering approach and good environmental management practices. Our findings support that early investment timing and intensity in environmental issues impact on the adoption of a proactive environmental management, which in turn helps to improve environmental performance. The findings also show that a firm's resources and competitive advantage act as mediator variables for a positive relationship between environmental protection and financial performance. This contribution is original because the present paper develops a comprehensive whole picture of this path process, which has previously only been partially discussed in the literature. In addition, this study clarifies a relevant point in the literature, namely that the effect of environmental protection on firm performance is not direct and can vary depending on the sector considered. Whereas competitive advantage in relation to costs influences financial performance in the IPPC law sector, the relevant influence in the hotel sector comes from competitive advantage through differentiation.     

A survey on the public perception of CCS in France

An awareness and opinion survey on carbon capture and storage (CCS) was conducted on a representative sample of French residents aged 15 years and above. About 6% of respondents were able to provide a satisfactory definition of the technology. The key question about ‘approval of or opposition to’ the use of CCS in France was asked twice, first after presenting the technology, then after explaining its potential adverse consequences. The approval rates, which were 59% and 38%, respectively, show that there is no a priori rejection of the technology. The sample was split in two to test for a semantic effect: half of the questionnaires used “Stockage” (English: storage), the other half “Sequestration”. Manipulating the vocabulary had no statistically significant effect on approval rates. Stockage is more meaningful, but does not convey the idea of permanent monitoring.     

Anoxic-aerobic treatment of the liquid fraction of cattle manure

Cattle manure from a dairy farm was treated in order to reduce its pollution potential. The manure came from a farm with 120 cows kept in stables in a free stall barn. As pretreatment, the manure is usually filtered on the farm using a screw press separator with a 0.5 mm mesh. Approximately 70% of the total filtered volume passes through the screen, thus constituting the liquid fraction. This fraction, with a composition of around 64,500 mg COD/l, 5770 mg total-N/l and 800 mg total-P/l, was subjected to centrifugation followed by a two-step biological treatment (anoxic-aerobic) to reduce organic matter (COD), nitrogen and phosphorus compounds. Centrifugation led to the following removal efficiencies: 35% total solids, 60% COD, 75% total phosphorus and 20% total nitrogen (mainly organic nitrogen). With the subsequent anoxic-aerobic treatment, average removal efficiencies of 85% for COD, 90% for total phosphorus and 75% for total nitrogen were achieved.     

Injury and loss concentration by sinkings in fishing fleets

Sinkings of fishing vessels, when accompanied by human loss, are accidents which lead to a great social upheaval, especially in the local area where they occur. In order to avoid or reduce these accidents, national governments must include in their legislation for this sector the appropriate safety measures. These resources and their distribution must be assigned in accordance with the needs of the accidentality, this requiring a detailed knowledge of the concentration of accidentality of a country’s fishing sector. In this context, the aim of the present work is twofold: first, to formulate a methodology for the fishing sector of a country, allowing the inequalities in the concentration of sinking accidents to be analysed; and second, to apply this methodology to the Spanish fishing fleet. Thus, two indices are constructed per region and type of fishing, for two variables: fishermen and vessels. Results are obtained both for the concentration of accidents and the associated Lorenz curves. An increase in the inequality in the spatial and functional distribution of these accidents is verified.     

Prediction models of CO, SPM and SO2 concentrations in the Campo de Gibraltar Region, Spain: a multiple comparison strategy

The 'Campo de Gibraltar' region is a very industrialized area where very few air pollution studies have been carried out. Up to date, no model has been developed in order to predict air pollutant levels in the different towns spread in the region. Carbon monoxide (CO), Sulphur dioxide (SO(2)) and suspended particulate matter (SPM) series have been investigated (years 1999-2000-2001). Multilayer perceptron models (MLPs) with backpropagation learning rule have been used. A resampling strategy with two-fold crossvalidation allowed the statistical comparison of the different models considered in this study. Artificial neural networks (ANN) models were compared with Persistence and ARIMA models and also with models based on standard Multiple Linear Regression (MLR) over test sets with data that had not been used in the training stage. The models based on ANNs showed better capability of generalization than those based on MLR. The designed procedure of random resampling permits an adequate and robust multiple comparison of the tested models. Principal component analysis (PCA) is used to reduce the dimensionality of data and to transform exogenous variables into significant and independent components. Short-term predictions were better than medium-term predictions in the case of CO and SO(2) series. Conversely, medium-term predictions were better in the case of SPM concentrations. The predictions are significantly promising (e.g., d (SPM 24-ahead) = 0.906, d (CO 1-ahead) = 0.891, d (SO2 1-ahead) = 0.851).     

Organic speciation of atmospheric particles in Alvão Natural Park (Portugal)

PM₁₀ continental rural background aerosols were collected during a summer field campaign (August–September 2006) at Lamas de Ôlo in the upper zone of the Alvão Natural Park, a mountain region of northern Portugal. In addition to the determination of the carbonaceous content by a thermal–optical method, the organic speciation of aerosols was performed by gas chromatography–mass spectrometry in an effort to evaluate photo-oxidation products of biogenic volatile organic compounds and other markers for source characterization. The detailed analysis revealed relatively high concentrations of polyols and short-chain dicarboxylic, tricarboxylic, hydroxycarboxylic, and oxocarboxylic acids, many of which are thought to be indicators of secondary aerosol formation, accounting for about 70% of global chromatographically resolved mass. Major photo-oxidation products of α- and β-pinene have been detected. The tracers for the photo-oxidation of isoprene comprise two diastereoisomeric 2-methyltetrols, C₅-alkene triols, and 2-methylglyceric acid, which have only recently been elucidated. In addition, the occurrence of levoglucosan and other biomass combustion tracers indicates that the site was affected by wildfires. This source contributed to more than 80% of the organic carbon mass during a period of strong forest fire influence.     

Management of MSW in Spain and recovery of packaging steel scrap

Packaging steel is more advantageously recovered and recycled than other packaging material due to its magnetic properties. The steel used for packaging is of high quality, and post-consumer waste therefore produces high-grade ferrous scrap. Recycling is thus an important issue for reducing raw material consumption, including iron ore, coal and energy. Household refuse management consists of collection/disposal, transport, and processing and treatment - incineration and composting being the most widely used methods in Spain. Total Spanish MSW production exceeds 21 million tons per year, of which 28.1% and 6.2% are treated in compost and incineration plants, respectively. This paper presents a comprehensive study of incineration and compost plants in Spain, including a review of the different processes and technologies employed and the characteristics and quality of the recovered ferrous scrap. Of the total amount of packaging steel scrap recovered from MSW, 38% comes from compost plants and 14% from incineration plants. Ferrous scrap from incineration plants presents a high degree of chemical alteration as a consequence of the thermal process to which the MSW is subjected, particularly the conditions in which the slag is cooled, and accordingly its quality diminishes. Fragmentation and magnetic separation processes produce an enhancement of the scrap quality. Ferrous scrap from compost plants has a high tin content, which negatively affects its recycling. Cleaning and detinning processes are required prior to recycling.     

Effects of sewage sludge blending on the coal combustion: a thermogravimetric assessment

Combustion of urban sewage sludge together with coal in existing infrastructures may be a sustainable management option energetically interesting for these materials, usually considered wastes. Thermogravimetric analysis was used to study the combustion of a semianthracite coal and the modifications undergone when adding a small percentage (2%, 5%, 10%) of sewage sludge. Both Differential Scanning Calorimetric analysis and Differential Thermogravimetry burning profiles showed differences between coal and sewage sludge combustion. However, the effects of adding a percentage of sewage sludge equal or smaller than 10% was hardly noticeable in terms of heat release and weight loss during the coal combustion. This was further proved by non-isothermal kinetic analysis, which was used to evaluate the Arrhenius activation energy corresponding to the co-combustion of the blends. This work shows that thermogravimetric analysis may be used as an easy rapid tool to asses the co-combustion of sewage sludge together with coal.