Use of the Dynamic Model `MAGIC' to Predict Recovery Following Implementation of the Gothenburg Protocol

Reduction of sulphur deposition causesrecovery of acidified surface waters. Processes in thecatchment delay recovery. The acidification model MAGICwas applied to the Vikedal and Tovdal rivers in southernNorway. Response in water chemsitry is delayed by 10–20 yr. The delay is due to release of old sulphate atVikedal and cation exchange at Tovdal. Assuming that theGothenburg protocol is fully implemented by the year2010, much of the predicted increase of ANC will occur inthe next 10 yr with a levelling off by about 2040. Ifnitrogen leaching increases in the future, however,recovery of ANC will not be as rapid, nor as complete.Critical load for acidity calculated by steady-statemodels is confirmed by the MAGIC predictions. Futurerequirement for mitigation measures such as liming willdecrease in the future as acid deposition decreases. Bythe year 2046 the liming requirement will be reduced byabout 45% at Vikedal and 65% at Tovdal. One of the mainpurposes of the Norwegian national monitoring programmeis to provide documentation of changes in environmentalquality due to long-range transported air pollutants.Modelling applications such as this clearly show that thedata fill this purpose.     

Briquetting of charcoal from sugar-cane bagasse fly ash (scbfa) as an alternative fuel

Brazil is the largest worldwide producer of alcohol and sugar from sugar-cane and has an extensive alternative program for car fuel which is unique. The objective of this work is to offer one management option of a solid residue produced by this industrial segment. The pressed sugar-cane bagasse is burned to produce steam and electricity by cogeneration. The combustion yields both bottom and fly ashes which contain high amounts of silicon oxide as a major component. Fly ash which contains a high volume (>30% by weight) of charcoal was used in this work. The ash was sieved to separate the thick charcoal from inorganic materials which are concentrated in the thinner fraction. The briquettes were hand pressed using charcoal mixed with a binder (starch) obtained from cassava flour (a tropical root). The results (density, mechanical resistance) obtained with 8% by weight of starch binder are presented here. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to characterize the ashes and the briquettes. The results show that sugar-cane bagasse fly ash (SCBFA) can be used to produce briquettes with an average density of 1.12 g cm^?3 and an average calorific value of 25,551 kJ/kg.     

Investigation of potentially toxic heavy metals in different organic wastes used to fertilize market garden crops

The benefits of using organic waste as fertilizer and soil amendment should be assessed together with the environmental impacts due to the possible presence of heavy metals (HMs). This study involved analysing major element and HM contents in raw and size-fractionated organic wastes (17 sewage sludges and composts) from developed and developing countries. The overall HM concentration pattern showed an asymmetric distribution due to the presence of some wastes with extremely high concentrations. HM concentrations were correlated with the size of cities or farms where the wastes had been produced, and HM were differentiated with respect to their origins (geogenic: Cr–Ni; anthropogenic agricultural and urban: Cu–Zn; anthropogenic urban: Cd–Pb). Size fractionation highlighted Cd, Cu, Zn and Pb accumulation in fine size fractions, while Cr and Ni were accumulated in the coarsest. HM associations with major elements revealed inorganic (Al, Fe, etc.) bearing phases for Cr and Ni, and sulfur or phosphorus species for Cd, Cu Pb and Zn.     

Making the CERCLA Criteria Analysis of Remedial Alternatives More Objective

This article shows how decision analysis techniques assisted decision makers in the critical RI/FS task of technology selection at a specific Superfund site. Each remediation alternative's performance was quantified by creating a set of objective evaluation measures tied to the criteria mandated in the comprehensive Environmental Response, Compensation and Liability Act of 1980. The evaluation measure scores were input into a quantitative decision analysis model used to rank alternatives based on their performance relative to the CERCLA criteria, and to provide insight to the sensitivity of the results to changes in decision maker preferences or technology performance. The model is designed to reflect the site decision maker's preferences and the site-specific characteristics within the framework of the nine CERCLA criteria. This model will give Superfund site decision makers an objective and transparent framework to evaluate remedial technologies.     

Innovative process routes for a high-quality concrete recycling

This study presents alternative methods for the processing of concrete waste. The mechanical stresses needed for the embrittlement of the mortar matrix and further selective crushing of concrete were generated by either electric impulses or microwaves heating. Tests were carried out on lab-made concrete samples representative of concrete waste from concrete mixer trucks and on concrete waste collected on a French demolition site. The results obtained so far show that both techniques can be used to weaken concrete samples and to enhance aggregate selective liberation (that is the production of cement paste-free aggregates) during crushing and grinding. Electric pulses treatment seems to appear more efficient, more robust and less energy consuming (1–3 kW h t^?1) than microwave treatment (10–40 kW h t^?1) but it can only be applied on samples in water leading to a major drawback for recycling aggregates or cement paste in the cement production process.