ABANDONED MINING SITES.
Concas1,2, A. Cincotti1,2, G. Cao1,2.
1 Dipartimento di Ingegneria Chimica e Materiali, Centro Interdipartimentale di Ingegneria e
Scienze Ambientali (CINSA), e Unità di Ricerca del Consorzio Interuniversitario Nazionale “la Chimica per l’Ambiente“ (INCA), P.zza D’armi 09123 Cagliari, Italy
2Laboratorio di Cagliari del Consorzio Interuniversitario Nazionale “la Chimica per l’Ambiente“,
c/o CRS4, VI Strada Ovest, ZI Macchiareddu, 1-09010 Uta, Cagliar,Italy
Intensive mining activity has been carried out during the last two centuries in Sardinia (Italy) and particularly in the area of Monte Narba, located in the district of Sarrabus in the South East of the island. Upon mine closure, the major sources of contamination in this area are represented by mine dumps, disposed along fluvial banks and beds of the valley. In particular the dumps contain about
300000 m3 of backfill material or mineral and metallurgical processing waste. These materials contain environmentally hazardous concentrations of heavy metals like Pb, Zn and Cd, and are susceptible of leaching and transport by atmospheric agents.
In spite of that, the area of Monte Narba, is characterized by remarkable chances from the naturalistic point of view and therefore the considerations above represents an inhibiting factor for the reclamation and the site recovery.
To this aim, this paper takes into account a possible remediation strategy for this area. to provide all the necessary steps for the implementation of a remediation strategy in this area.
First, the site has been characterized from the pollution point of view by performing a risk analysis using a public domain software. The analysis showed that the main sanitary risks are those ones, deriving from the presence of high Pb concentrations, which then becomes the target of the proposed remediation technique.
Because of dump instability, it was impossible to suggest an in-situ technique of remediation, so that the potential validity of an ex-situ technique is tested. It is proposed to perform a non-oxidative acid leaching by means of HCl or HCl – NaCl or HCl-CaCl2solutions in mixed batch reactors in order to extract the Pb from the waste materials and obtain an harmless and easy- disposable product. In the experimental this technique is studied at the laboratory scale in order to establish the efficiency of extraction and to study its sensitivity to the processing parameters so that an optimal set of parameters could be found. The parameters investigated were: solid/liquid ratio, acid concentration, temperature and mixing energy. The results of the experimental section show that the extractive phenomenon is strongly influenced by chloride anions concentration in solution, temperature and solid/liquid ratio. Combining this tree factors it is possible to reach high extractive efficiencies for Pb removal.
Finally, although the scale up of the process requires more detailed information, a potential plant flowsheet for the application of the technique to real scale is proposed.
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OLIVE-MILL WASTEWATER TREATMENT BY ARTHROBACTER SPP STRAINS Marabottini, R., D’Annibale, A., Ricci, M, Stazi, S.R., Giovannozzi Sermanni, G.
Dipartimento di Agrobiologia & Agrochimica Università degli Studi della Tuscia Viterbo
The olive oil extraction process generates an effluent which is commonly termed olive-mill wastewater (OMW). Huge amounts (30 x 107 m3) of this effluent are annually produced in the Mediterranean area causing environmental concern. The environmental risks associated with olive- mill wastewater are mainly due to its high organic load (COD 30000-150000) and to its phenolic components. Several ecotoxicological effects have been associated to the phenolic fraction of OMW, whose concentration may widely range from 1 to 15 g l-1in dependence of several factors (extraction process; olive cultivar, harvesting period). The monomeric components in OMW constitute a relevant aliquot of the phenolic fraction and include several compounds, such as substituted and unsubstituted catechols, cinnamic acid derivatives (caffeic acid, ferulic acid), tyrosol, hydroxytyrosol and hydroxy- and methoxy-substituted benzoic and phenylacetic acids. The evaluation of the ecological risks associated with the antibacterial and phytotoxic activity of OMW is an important prerequisite prior to its spreading on soil. Bacteria belonging to the genus Arthrobacter are ubiquitous colonizer of soil ecosystems. For this reason, the use of these species as a biomarker of pollution problems has been suggested. In addition, several reports claim the degradation efficiency of these species on aromatic substances both in pure and mixed cultures. In the present study, OMW underwent an aerobic treatment with different species of Arthrobacter, including A. giacomelloi DSMZ 3681, A.
nicotianae DSMZ 20123 and A. globiformis DSMZ 20124. All the strains tested were able to grow
and to partially degrade the monomeric aromatic components in OMW. Reversed phase HPLC analyses conducted on ethyl acetate extracts showed that the strains under study exhibited different specificity of attack on the monomeric aromatic components. For instance, A. giacomelloi efficiently degraded ortho-diphenols (catechol, 4-methyl catechol, hydroxytyrosol) while A. nicotianae was more active on polymethoxylated structures, such as syringic and synapic acids. The strains under study were unable to significantly affect the molecular weight distribution of the water-soluble polymeric fraction, as assessed by size-exclusion chromatography.
Tests based on germination/root elongation of water cress seeds (Lepidium sativum L.) showed an evident phytotoxic effects due to the wastewater. OMW treatment with A. giacomelloi resulted in a marked toxicity reduction. In contrast, A. nicotianae, enhanced phytotoxicity, probably due to the accumulation in OMW of aromatic degradation intermediates proving to be more toxic than parent compounds.
MODELIZATION OF THE SEMI-DRY PROCESS FOR HCL REMOVAL FROM FLUE