EASY RESPIROMETRIC METHOD EASY RESPIROMETRIC METHOD FOR THE OPTIMISATION OF D FOR THE OPTIMISATION OF D DIESEL‐CONTAMINATED SOIL BIOREMEDIATION DIESEL CONTAMINATED S CONTAMINATED S SOIL BIOREMEDIATION Jubany I. Corcho D Rovira M Muelle A. Martí V. , Jubany I 1, Corcho D. 2, Rovira M. 1, Muelle A 2 ,Martí V 1,3 1CTM Technological Center Foundation Environmental Technology Area (UPC) Av B CTM, Technological Center Foundation, Environmental Technology Area (UPC), Av. B Bases de Manresa, 1, E‐08242 Manresa (Spain) Bases de Manresa 1 E 08242 Manresa (Spain) 2 INTRAVAL S.L. Llull, No. 109, 2nd floor, E‐08005 Barcelona (Spain) 2 INTRAVAL S L Llull No 109 2nd floor E 08005 Barcelona (Spain) 3Department of Chemical Engineering Technical University of Catalonia (UPC) ETSEIB Av Diagonal 647 E 08028 Barcelona (Spain) Department of Chemical Engineering, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal, 647, E‐08028, Barcelona (Spain) INTRODUCTIONPetroleum hydrocarbon (TPH) contamination in soils is one of the ma environmental problems in Spain due to bad industrial and waste ainmanagement practices performed in the last decades The biological treatment is one of the most cost‐effective treatments due to its low decades. cost effectiveinvestment and treatment costs (NFESC, 1996). A useful technique for the determination of bacterial activity in biological processes like thebiological ilbi l gi l soil treatment i the respiration technique that can b used to relate the O2 consumption with the contaminant removal. H is h pi i h iq h be d l h pi ih h i l Howeverits potential has not been thoroughly exploited in the soil treatment fie This work shows a low cost and easy respirometric method for the eld. eld low‐costlaboratory testing of contaminated soil The method was tested using m soil. microcosms experiments with hydrocarbon‐contaminated soil soil. MATERIALS AND METHODS MATERIALS AND METHODS Microcosms setup Respirometic method: A series of microcosms (Table 1) were set up for the treatment of Throughout the experiment, the oxygen of the air chamber of diesel‐contaminated diesel contaminated soil (16 7 g TPH/kg d m ) amended with (16.7 d.m.) ith the jars was periodicall meas red b introd cing an o gen as periodically measured by introducing oxygen chemical nutrients (NFESC 1996) and a bulking agent (a mixture (NFESC, probe into the jars through a hole in the lid which was sealed of sawdust and wood chips) to provide optimal porosity. F f d d d hip ) p id p i l p i y For with i l i g tape (Fig i h insulating p (Figure 1) Th slope of the air oxygen ( 1). The l p ) f h i yg each test an abiotic control (named 0) was also set up (with 4 g test, concentration with time (d(O2%)/dt) was used to calculate the HgCl2/kg soil). g / g ) oxygen uptake rate (OUR in mg O2/d kg d.m.) using Eq. 1. yg p ( g / g ) g q Table 1. Experimental conditions of microcosms p Each microcosm consisted on a 1 L 2.7421∙ 2 7421∙ Vair d(O2%) OUR = ∙ Eq. Eq 1 Bulking agent g g Nutrients Test Microcosm glass jar containing M dt (% in wet weight) (% i t i ht) addition dditi 160 g of the soil‐ soil 0 0, A 0 A 0 No bulking b lki agent t Vair is the volume of air in each jar 1 0, A, , C 0, A, B, C 100 Yes mixture and added (in L) and M is the dry weight of 2 0, A, B, C 20 Yes water ( 0 % of (70 f the il (in ) in the i th soil (i g) i th microcosm. 3 0, A, B, C 0 A B C 30 Yes field capacity) capacity). Figure 1. Air chamber oxygen Figure 1. Air chamber oxygen Microcosms were k t f Mi kept for 6 weeks at 20ºC TPH were k t 20ºC. TPHs measurement of a microcosm setup. measurement of a microcosm setup. measured at the beginning and at the end of the experiment experiment. RESULTS The oxygen measurements in the microcosms of Tests 1, 2 and 3 clearly showed oxygen consumption due to the biological activity. Figure 2 shows th oxygen profile f T t 1 which was similar t Test 2 and 3 N li ibl oxygen consumption was d t t d i T t 0 Fi h the fil for Test hi h i il to Te t d 3. Negligible ti detected in Test 0. This fact indicated that the contaminated soil without bulking agent and without added nutrients had no capacity to degrade TPHs As t TPHs. expected, oxygen i abiotic control microcosms did not change d t the i hibi i of b p d, yg in bi i l i h g due to h inhibition f bacterial activity. i l i iy Figure 2. Oxygen Figure 2 Oxygen profile of microcosms in Test 1 of microcosms in Test 1 Figure 3. OUR pr f l of Tests 1, 2 and 3. i rofile f d Figure 4. Percentage of TPH removal i f l OUR was calculated for Tests 1, 2 and 3 (Figure 3). The OUR was c , ( g ) clearly higher in Tests 2 and 3 than in Test 1 indicating that higher y g g g bacterial activity was taking place in these tests Based on these res tests. spirometric results experimental conditions in Test 3 were the best results, conditions for bacterial activity. Therefore, it can be stated that t increase of the mixture porosity (due to higher bulking agent the concentration) f t ti ) favoured th b t i l activity d t t d as oxygen re i ti rate. Thi was confirmed with TPH d t since hi h TPH d the bacterial ti it detected espiration t This fi d ith data i higher removal was obtained as higher was the porosity of the mixture (Figu 4) ure 4). CONCLUSIONS An easy respirometric method was developed for testing the bioremediation potential of hydrocarbon‐contaminated soil. The method was based hydrocarbon contaminated on the periodic measurement of the air oxygen of jars containing the tested soil using an oxygen probe. h d f h f h d l b The method was used to detect the best amendment conditions for the biotreatment of a hydrocarbon‐contaminated soil without the need for hydrocarbon contaminated expensive chemical analyses as TPHs. Results obtained with the respirometric method were in agreement with results obtained with TPH analysis. p y p g y The developed method is a promising method to be used as a tool for sm scale screening tests previous to pilot or industrial treatments for waste mall‐scale mall management companies that need cheap and reliable techniques techniques. REFERENCES • NFESC (1996). Biopile design and construction manual. TM‐2189‐ENV. Naval Facilities Engineering Se ( ) p g g g ervice Center.