| AUTOCHTONOUS MICROBIAL COMMUNITIES HAVE A NATURAL CAPABILITY FOR UPTAKE, METABOLIZE AND MINERALIZE ORGANIC COMPOUNDS POLLUTANTS AS SOURCE OF CARBON AND ENERGY. THIS METABOLIC CAPACITY IS PARTICULARLY RELEVANT WHEN A PRISTINE SITE IS POLLUTED DUE TO OIL SPILLS WHERE MIXTURES OF HYDROCARBONS ARE BIOLOGICALLY REMEDIATED BY MEANS OF THE NATIVE MICROBIAL COMMUNITIES (BIOREMEDIATION). THEREFORE, THE BIOREMEDIATION OF HYDROCARBON CONTAMINATED SOILS CORRESPONDS TO THE BIOLOGICAL DEGRADATION THROUGH TRANSFORMATION AND/OR MINERALIZATION OF ORGANIC COMPOUNDS, TO REDUCE THEIR ENVIRONMENTAL CONCENTRATION TO ACCEPTABLE LEVELS. BIOREMEDIATION CAN BE ACCELERATED BY STIMULATING AUTOCHTONOUS MICROBIAL COMMUNITIES; THERIR SUCCESS DEPEND OF TYPE AND DENSITY OF THE MICROORGANISMS PRESENT IN SOILS, SPECIFIC CHARACTERISTICS OF THE SOIL MATRIX, CHARACTERISTICS AND CONCENTRATION OF POLLUTANTS AS WELLA AS THE MAINTENACE OF ENVIRONMENTAL VARIABLES SUCH AS TEMPERATURE, MOISTURE CONTENT AND PH. TREATMENTS CONDUCTED IN CONTROLLED SYSTEMAS SUCH AS BIOREACTORS, HAVE SHOWN TO BE EFFECTIVE AND EFFICIENT. EX-SITU BIOREMEDIATION APPLIED TO CONTAMINATED SOILS, PARTICULARY BY COMPOSTING, HAVE BEEN RELEVANT DUE TO ITS FEASIBILITY TO APPLY A CO-TREATMENT OF WASTES TAKING ADVANTAGES OF NUTRIENT BALANCES. MAIN ADVANCES IN BIOREMEDIATION OF HYDROCARBONS HAVE OCURRED MAINLY AT LABORATORY SCALES IN SOILS CONTAMINATED WITH ONE-COMPOUND. NEVERTHELESS, THERE ARE NO SIGNIFICANT STUDIES RELATED TO BIOREMEDIATION ON REAL CASES OF CONTAMINATION (SPILL FUELS, OILS, SOLVENTS Y CO-TREATMENT OF WASTES), AND THERE IS SCARCE KNOWLEDGE OF THE EFFECTS AND CHANGES ( BEHAVIOR) IN THE MICROBIAL COMMUNITIES DURING TREATMENT. THEREFORE, ITS IS UNCLEAR WHETHER THE BIODEGRADATION OF CONTAMINANTES CORRELATES WITH THE DIVERSITY AND CHARACTERISTICAS OF THE COMMUNITY OF MICROOERGANISMS PRESENT IN SOILS, OR IF THESE CHANGES ON MICROBIAL COMMUNITIES ARE RELATES TO DEGRADATION CURVES. FURTHERMORES, THERE IS LITTLE INFORMATION REGARDING THE JOINT-TREATMENT OF CONTAMINATED WASTE AND ITS FEASIBILITY OF IMPLEMENTACION TO DESERT SOILS. IT IS NECESSARY TO RUN FURTHER RESEARCH TO ELUCIDATE THE APPLICABILITY OF THE COMOSTING PROCESS TO POLLUTED DESERT SOILS AND ITS IMPACT ON THE BIODIVERSITY OF MICROBIAL COMMUNITIES. A REAL COMMON CASE ARE THE REPETITIVE, ALTHOUGH SMALL, SPILLS OF DIESEL FUEL AND LUBRICANT OIL DURING MACHINERY REPAIR AND MAINTENANCE, AS WELL AS ACCIDENTS BETWEEN TRUCKS WITHIN THE CHILEAN MINING INDSUTRY, WHERE DESERT SOILS AND SAWDUST HAVE BEEN USED AS CHEAP SORBENT MATERIALS TO CONTROL THESE OIL SPILLS. THIS STUDY CONTRIBUTES TO ESTABLISH THE FEASIBILITY OF BIOREMEDIATION USING AERATED IN-VESSEL COMPOSTING, OF AND AGED FUEL-CONTAMINATED DESERT MINING SOIL AND SAWDUST IN THE ATACAMA REGION, AS A COST-EFFECTIVE ALTERATIVE OF TREATMENT. THE REMOVAL OF TOTAL ORGNAIC COMPOUNDS (TOCS) AND THE CHANGES IN THE MICROBIAL DIVERSITY DURING COMPOSTING AT LABORATORY SCALE UNDER CONTROLLED CONDITIONS OF TEMPERATURE, MOISTURE AND VENTILACION, WERE STUDIED. 30 CYLINDRICAL POLY-VINYL-CHLORIDE AERATED COMPOSTING REACTORS WERE SET-UP AT LABORATORY-SCALE AND CONTINUOUSLY OPERATED DURING 56 DAYS. THE COMPOSTING REACTORS WERE OPERATED USING FIVE DIFFERENT SOIL TO SAWDUST RATIONS (S:SD, 1:0, 3:1, 1:1, 1:3, 0:1), UNDER MESOPHILIC TEMPERATURE (30-40øC), 50 POR CIENTO MOISTURE CONTENT AND CONSTANT VENTILATION (16 L/MIN). THE FUEL CONTAMINATED DESERT SOILS AND CONTAMINATED SAWDUST WERE MIXED AND AIR-DRIED PRIOR CONDUCTING THE COMPOSTING TREATMENT. CONCENTRATION OF TOTAL ORGANIC CARBON (TOC) IN THE COMPOSTING REACTORS WAS MONITORED ACCORDING TO STANDARD METHODS (USEPA). USING BIOMOLECULAR AND METABOLIC TOOLS, REMOVAL CURVES OBTAINED WAS RELATED TO CHANGES IN THE DIVERSITY OF MICROBIAL COMMUNITIES. TERMINAL-RESTRICTION FRAGMENT LENGTH POLYMORPHISM (T-RFLP) TESTS WERE CONDUCTED IN ORDER TO ESTIMATE THE PRESENCE AND CHANGES DURING THE TREATMENT OF OPERATIONAL TAXONOMIC UNITS (O.T.U.) AND BIOLOG ECOPLATES TM TO DETERMINATE METABOLIC CHANGES OF THE MICROBIAL COMMUNITIES. RICHNESS AND IDVERSITY WERE DETERMINED FOR EACH MICROBIAL COMMUNITY, AND WERE EXPRESSED AS THE SHANNON-WIENER INDEX (H'). DIFFERENT REMOVAL CURVES WERE OBTAINED WITH SIMILAR REMOVAL PERCENTAGES BETWEEN REACTORS (RANGE 35 POR CIENTO - 59 POR CIENTO) AFTER 56 DAYS OF TREATMENT. THE PROPORTION OF SAWDUST, THE TIME OF TREATMENT AND INTERACTION BETWEEN BOTH PARAMETERS HAD A SIGNIFICANT EFFECT (P<0.050) ON THE TOC REMOVAL. HIGHER LEVELS OF SAWDUST CORRELATED TO AN INCREMENTAL NUMBER OF O.T.U. IN THE MICROBIAL COMMUNITIES BUT SHOWED NO CORRELATION WITH THE REMOVAL CURVES. METABOLIC PROFILING EXHIBITED A DIFFERENTIAL DISPLAY THROUGHOUT THE TREATMENT, EXPLAINING DIFFERENTIAL STRUCTURE'S COMMUNITIES. THE FINAL CHAPTERS OF THIS THESIS INTEGRATE THIS KNOWLEDGE TO DRAW LINES TO FUTURE RESEARCH AND TO UNDERSTAND HOW BIOLOGICAL TECHNOLOGIES CAN SUPPORT BIOENGINNERING SYSTEMS. |