Miquel Rigola

Heavy metal binding to anaerobic sludge

Heavy metal interaction with anaerobically digested sludge was investigated using copper, cadmium and nickel chloride salt solutions. The behaviour of the well-known glycine-metal aqueous system was compared with the behaviour of the sludge-metal system. When equilibrium pH values are presented against the initial metal concentration for the glycine-copper system the profile obtained shows a sharp peak. This behaviour is similar to the behaviour of the experimental sludge-copper system. The peak also appears for cadmium and nickel-glycine systems. However, it is not as pronounced as in the glycine-copper system and cannot be observed in the sludge-metal systems. The similar behaviour of both copper systems suggests that the metal binding mechanism of the sludge involves amino acid functional groups which are present in the cell wall. Due to this similarity, an apparent molarity of the sludge can be evaluated by sludge titration with copper (II). The value obtained can be expressed as mmols of equivalent glycine per gram of sludge.

Incorporating cleaner production and environmental management systems in environmental science education at the University of Girona

The field of environmental science and engineering is rapidly evolving. The focus has shifted more and more from the end‐of‐pipe to pollution‐prevention oriented strategies for sustainability. Cleaner production requires new attitudes, knowledge and skills for all professionals to assure that preventive environmental strategies are integrated into planning and development activities throughout society. When preparing the curriculum for the new studies in Environmental Sciences at the University of Girona in 1993, it was considered essential to introduce pollution‐prevention‐oriented courses for future graduates. “Compatible Technologies” and “Minimisation of the Industrial Environmental Impact” are two courses supplementing each other to address the integrated approach to industry environmental issues. Describes the objectives of these two courses as well as the main topics included, and the methodology applied.

Issues in System Boundary Definition for Substance Flow Analysis: The Case of Nitrogen Cycle Management in Catalonia

The great complexity of the nitrogen cycle, including anthropogenic contributions, makes it necessary to carry out local studies, which allow us to identify the specific cause-effect links in a particular society. Models of local societies that are based on methods such as Substance Flow Analysis (SFA), which study and characterise the performance of metabolic exchanges between human society and the environment, are a useful tools for directing local policy towards sustainable management of the nitrogen cycle. In this paper, the selection of geographical boundaries for SFA application is discussed. Data availability and accuracy, and the possibility of linking the results with instructions for decision making, are critical aspects for proper scale selection. The experience obtained in the construction of the model for Catalonia is used to draw attention to the difficulties found in regional studies.

The nitrogen balance for Catalan agriculture soils and livestock sectors

A comprehensive assessment of nitrogen metabolism in Catalonia (NE region of Spain) has been performed by the method of Substance Flow Analysis (SFA). Being agriculture soils and livestock sectors where the human food production stands, this paper is focused in the analysis of nitrogen dynamics in these sectors. Groundwater contamination, nitrogen accumulation in transition reservoirs (landfills, forest) and significant exports to the Mediterranean Sea, have been identified as the main associated environmental impacts. The study gives proof that Catalonia is a net receiver of nitrogen without a strategic evaluation behind the management of the N microsystem in Catalonia. This study is a good backup for the planning of such a management plan.

Competitive biosorption of copper, cadmium, nickel and zinc from metal ion mixtures using anaerobically digested sludge

The biosorption of four metal ions, cadmium, copper, nickel and zinc from multicomponent mixtures in aqueous solution by anaerobically digested sewage sludge is reported. The metal competition study was performed on binary metal systems where the two metals present had the same initial concentration. An increment of the total metal adsorption was obtained in all tests when compared to the single metal systems. The same behaviour was observed when a mixture of all the four metal ions was studied. The metal-sludge affinity order found was the same in single and multi-component (binary and quaternary) mixtures copper, cadmium, zinc and nickel. Copper has been demonstrated to have the capacity to desorpt cadmium and zinc previously bound to the sludge.