By Msc. José Alfonso Álvarez González and others
The chemical and microbiological characterization of the petrolized solid waste located outside the pool of the Birama Quarry belonging to the Petroleum Extraction and Drilling Company (EPEP-Centro) in the province of Matanzas, Republic of Cuba was carried out. The Bioremediation process was applied.
The chemical and microbiological characterization of the petrolized solid waste located outside the pool of the Birama Quarry belonging to the Petroleum Extraction and Drilling Company (EPEP-Centro) in the province of Matanzas, Republic of Cuba was carried out. The Bioremediation process was applied through the technique of biostimulation of autochthonous microorganisms to petrolized solid waste, using residual sludge or digested sludge from a sewage treatment plant as a source of microorganisms and essential nutrients (nitrogen and phosphorus). .
For a period of 80 days, as part of the analytical, chemical and microbiological monitoring, it is possible to reduce the levels of total hydrocarbons in oil to values close to 1%, a limit recommended by the specialized literature for soils recovered through biodegradative processes, allowing new controlled incorporation of waste in the area. Significant biodegradation rates were obtained for the Asphaltene fraction, 42%, considered resistant to the degradation process by the action of microorganisms.
The economic analysis of the applied bioremediation process reported low values per m3 of treated petrolized solid waste, resulting in a technology that is easy to apply and with significant economic benefits.
The protection and conservation of natural resources, considered the patrimony of all the people, must constitute for any contemporary civilized society more than an obligation, a commitment of all those who directly or indirectly influence them.
Oil exploration - production in recent years has been increasing, making it necessary to establish a balance between productive development and environmental protection.
The Empresa de Extracción y Perforación de Petróleo Centro, located in the province of Matanzas, Republic of Cuba, has for years stored solid waste from the drilling process and the bottoms of crude oil storage tanks, in a pool waterproofed with concrete. This petrolized solid waste has not received any treatment, causing a serious environmental impact.
Biological treatments, especially the Bioremediation process through the biostimulation technique of autochthonous microorganisms, has been used with favorable results in recent times in Cuba. This process, novel still due to ongoing research, uses inorganic fertilizers as sources of essential nutrients to enhance microbial activity.
Álvarez et al. In 2004, they carried out preliminary studies on the use of sewage sludge from sewage treatment plants in the bioremediation process of petrolized solid waste at the “Ñico López” Refinery. These bench-scale tests reported satisfactory results, resulting in the beginning of investigations in this field, in which it is concluded that these wastes are a source of nutrients and biodegradable microorganisms of all hydrocarbon fractions, which can enhance the Bioremediation process. of oil contaminated soils, petrolized solid waste and drilling cuts that are generated in oil companies.
The general objective of this work is the application of the Bioremediation process to drilling cuts and petrolized solid waste in the area surrounding the pool of the Birama Quarry of the Petróleos Centro Perforation - Extraction Company, by means of the bio-stimulation technique of the endogenous microorganisms, using the residual sludge or digested sludge from domestic wastewater treatment plants, as a source of hydrocarbon biodegradable microorganisms and essential nutrients (nitrogen, phosphorus).
Materials and methods
The Birama Quarry is an area located on the north coast of the province of Matanzas, where the Empresa de Perforación - Extracción de Petróleo Centro (EPEP Centro), for years has been depositing waste from drilling, extraction and commercialization of crude oil without treatment. any. Currently this place is saturated, due to the large volume of solid waste that it stores, which is necessary to provide a solution as soon as possible and that is environmentally safe.
The Bioremediation treatment was not applied directly to the solid waste stored in the quarry, but to those located in an area adjacent to it.
The dimensions of the treated area were: Length: 150 m, Width: 15 m, Depth: 0.50 m, Volume of initial petrolized solid waste: 1 125 m3 New additions of waste not contemplated were made without authorization of the project executors, in the months of May and August (12 m3 respectively), so the final volume of treated petrolized solid waste was 1 149 m3
Soil sampling, petrolized solid residue and Residual sludge
For the sampling of petrolized solid waste, a star type sampling recommended by the Japanese specialist Dr. Itaru Okuda was used. The samples were collected and packed in aluminum bags (ISO 5667) that were preserved in freezing until their subsequent processing and analysis. In addition, they were homogenized, dried, and sieved through a 2 mm sieve, from which a representative sample was taken to be analyzed.
The sample of residual sludge or digested sludge was taken punctually in the final discharge of residual sludge or digested sludge towards the drying bed of the Taino I urban wastewater treatment plant. The sample was packed in sterile 1-liter bottles. and preserved cold until use in the microbiology laboratory (ISO 10381–6, 1993). To later perform the microorganism count, and determine the concentration of nutrients.
Chemical and microbiological characterization of the petrolized solid residue and the residual sludge or digested sludge.
1. Solid petrolized residue.
We proceeded to the determination of fats and oils, total petroleum hydrocarbons, total nitrogen, total phosphorus, Total Heterotrophic Microorganisms, Biodegradable Microorganisms and Heavy metal content, according to established standards.
For the determination of metals, the samples were subjected to a previous cleaning treatment of foreign matters, drying and sieving, for their subsequent chemical treatment with an acid mixture of HNO3 / H2O2 / HCl, according to EPA 3050B standard. The solutions obtained in duplicate were analyzed in a GBC atomic absorption spectrophotometer, model AVANTA ?.
2. Residual Sludge or Digested Sludge.
Total nitrogen and phosphorus contents, Total Heterotrophic Microorganisms, Biodegradable Microorganisms, were determined according to standard methods.
Application of Bioremediation to treat petrolized solid waste from the Birama Quarry.
The Bioremediation process was applied to the mixture of petrolized solid waste - clean soil, located in the perimeter area of the Birama Quarry pool. The Bioremediation process was applied as described below:
1. Homogenization of the impacted area.
The clean soil + residue mixture was removed using appropriate mechanical equipment (bulldozer coupled to a router), achieving homogenization of the area.
2. Addition of Residual Sludge as a source of Nutrients.
In this work, nitrogen, phosphorus and potassium were used as a source of essential nutrients, which stimulate microbial growth, residual sludge or digested sludge, generated in the Taíno 1 Plant belonging to the Aguas Varadero company, which provides treatment to the waters sewage waste from a hotel complex on the Hicacos Peninsula.
Previous studies carried out on a bank scale by Álvarez et al., 2004, reported application doses of residual sludge in a range between 0.01 and 1.5% of the volume of solid waste to be treated, with which the residual doses to be added were calculated. Two additions of these wastes were made, using tank cars, during the assembly of the treatment and after 80 days. At 90 days manual fertilization of dry residual sludge was carried out. Figures 4-9 show the production-fertilization operation carried out in the applied bioremediation process.
1. Moistening and Aeration.
Bioremediation is a fundamentally aerobic process, for which the periodic incorporation of oxygen into the soil is necessary. This activity was achieved through a bulldozer coupled to a ruster (Figure 10), with monthly frequency. The artificial moistening was carried out using a tank car for the only time in the assembly phase of the treatment (Figure 11). The precipitations that occurred during the process time guaranteed the necessary humidity conditions, 60-80%, for the proper development of the process.
Analytical monitoring of the applied Bioremediation treatment.
To determine the effectiveness of the applied treatment, the following physical-chemical analyzes were carried out:
|Analysis||Testing method||Time (days)|
|pH||NC 32: 1999||0,30, 80, 110,180|
|Fats and Oils (G / A)||Abbout S.A, 2000||0,30, 80, 110,180|
|Total Petroleum Hydrocarbons (HCTP)||APHA 5520F||0,30, 80, 110,180|
|Saturated, Aromatics, Resins and Asphaltenes (SARA)||Abbout S.A, 2000 Sawatzky, 1976||0, 80, 180|
|Total Nitrogen (NT)||BBSSC001, 1998||0, 30, 80,83,110,180|
|Total Phosphorus (PT)||FAO, 1975||0,30, 80, 110,180|
|Total microorganism count (MOT)||Alef and Nannipieri, 1998|
ISO 6887, 1993
ISO 4833, 1991
|0,30, 80, 110,180|
|Biodegradable microorganism count (MOB)||APHA, 1975|
Finerty, W and others, 1983
Solana, A. M., 1985
|0,30, 80, 110,180|
|Viale and Infante, 1997.||0,30, 80, 110,180|
The qualitative chromatographic profile was performed on the fraction of saturated and aromatic hydrocarbons, using a KONIK gas chromatograph, 400B series with flame ionization detector (FID) with a 30 m long, 0.32 mm long BP-5 stationary phase capillary column. gave and 0.5µm film thickness.
The% removal of hydrocarbons was calculated according to the following expression:
Initial H / C Concentration - Final H / C Concentration
Removal (%) = ————————————————————————– * 100
Initial H / C Concentration
Results and Discussion.
1. Chemical and microbiological characterization of the petrolized solid residue of the quarry Birama.
The solid petrolized waste (RSP) disposed of in the area surrounding the Birama Quarry, EPEP Centro, Matanzas, to which the Bioremediation process will be applied through the biostimulation technique of the microorganisms present in it, is mainly composed of soils contaminated by hydrocarbons due to breakdowns in the crude oil marketing system (pipelines in pipelines, storage, loading, unloading, etc.), drilling residues generated in the oil extraction process, and due to inadequate cleaning practices for tank cars used in the transportation of crude oil. Tables 1-3 report the chemical and microbiological characteristics of the aforementioned waste.
Table 1. Chemical characterization of RSP, expressed in mg / Kg dry basis.
|Shows||G / A||HCTP||NT||PT|
|RSP||179 220||90 210||1.29||0.13|
RSP: Solid Petroleum Residue G / A: Fats and Oils
HCTP: Total Petroleum Hydrocarbons, NT: Total Nitrogen PT: Total Phosphorus
As can be seen in the table above, the concentration values of fats and oils and hydrocarbons turned out to be very high, normal levels to be found in these residues. It is also appreciated that the nitrogen and total phosphorus values are low, which indicates the need to add some source of these nutrients for the bioremediation process to be carried out satisfactorily.
Table 2. Concentrations of total and biodegradable microorganisms, expressed in CFU / g
|Shows||Total Heterotrophic Microorganism Count||Biodegradable Microorganisms Count|
|RSP||9.55 x 10 8||5.35 x 10 6|
RSP: Solid Petroleum Waste
Table 2 reports the concentrations of total and biodegradable heterotrophic microorganisms present in the solid petroleum residue to be treated, which are within the range reported by other authors (Ercoli, 2000 and Infante, 2001) to achieve a satisfactory development of the process of Bioremediation using the biostimulation technique, between 105 to 106 CFU / g soil for the case of total heterotrophic microorganisms and between 103 to 104 CFU / g soil for degrading microorganisms.
Table 3. Levels of toxic substances present in the petrolized solid residue, expressed in µg / g
|RSP||36,6||< 2,5||49,4||< 50||116,9||10,9||836,2|
|CUPET (1)||150||300||300||20 000|
(1) Regulation 08/99, CUPET
As can be seen in table 3, the concentration levels of Pb, Zn, Cr and Ba are below that stipulated in the reference standard. The other substances reported, even in low concentrations, their values are given by the use of these in the formulation of the muds used in the drilling process of oil wells.
2. Chemical and microbiological characterization of the residual sludge or digested sludge from the Taino sewage treatment plant 1
Table 4 reports the levels of total microorganisms, biodegraders and nutrients of the digested sludge used in the biostimulation of the autochthonous microorganisms of the petrolized solid waste from the area surrounding the pool of the Birama quarry.
Table 4. Total microorganisms, biodegradable and nutrients.
|Shows||Total Aerobic Bacteria (CFU / g soil)||H / C Biodegrading Bacteria (CFU / g soil)|
(mg / kg)
(mg / kg)
|Residual sludge||7.50 x 108||2.5 x 107||2.58||0.56|
It should be noted that although the levels of total nitrogen and total phosphorus for the analyzed point sample of residual sludge turned out to be low, for the mean reported in the literature between 3 - 4% (Ameneiros et al, 2003), it was decided, by satisfactory experiences of the authors in 2005, obtained in the treatment of petrolized solid waste on a bench scale, use these digested sludge or sludge from the Taíno 1 Plant as a source of nutrients in the field-scale Bioremediation process, providing in this way, an environmentally safe final disposal of these wastes.
3. Monitoring of the Bioremediation treatment applied.
Table 5 reports the results of the fundamental parameters measured for the monitoring of the Bioremediation process of the aforementioned petrolized solid waste.
Table 5. Results obtained in the bioremediation treatment applied.
G / A
(mg / Kg)
(mg / Kg)
(mg / Kg)
(mg / Kg)
|t = 0|
|105 320||36 990||–||25.62||23.62|
|t = 30||–||78 180||24 170|
|t = 80|
|63 910||17 820|
|t = 83|
|76 350||23 350|
|t = 110|
|52 140||2 676|
|t = 180|
|83 540||19 430||–|
(1)% Removal with respect to Fats and Oils.
(2)% Removal with respect to Total Petroleum Hydrocarbons.
The soil pH of the treatment area was kept within that recommended by other authors (Ercoli, 2001) (Infante, 2001), thus favoring the good development and growth of the existing autochthonous microflora.
The table above shows a decrease in the levels of fats and oils over time. In the case of total oil hydrocarbons after 80 days, values very close to 1% are obtained, a level recommended by international standards to conclude the Bioremediation process (Louisiana, 2000). In Figure 12 - 13 the notable improvement and recovery of the treated land and growth of vegetation in the treatment area are graphically observed.
During the first 30 days, there is a decrease in the concentration of fats and oils and total petroleum hydrocarbons, represented by a degradation rate of 25.76 and 34.66% respectively, a result higher than the 25% recommended by other authors as satisfactory for this type process (Infante, 2001) (Ercoli, 2001). In general, 110 days after applying the treatment, a reduction in the total hydrocarbon content of 92.71% was obtained, and of 50.49% for fats and oils, favorable values for this type of treatment.
Figures 14 -15 show graphically the variations in the concentrations of fats and oils and petroleum hydrocarbons, as well as the new additions of petrolized solid waste that occurred during the period evaluated in this report (Fig13 -14).
Table 5 also shows the variations in the contents of Nitrogen and total Phosphorus in the treated area, showing a marked decrease over time in the levels of these substances, due to their use by microorganisms as essential nutrients for their growth and development of the biodegradative process, resulting in sufficient levels of these compounds in the residual sludge for the proper development of the hydrocarbon degradation process.
Table 6 shows the concentration levels of the total oil components extracted from the soil over time (saturated, aromatic, resins and asphaltenes). The highest concentration of hydrocarbons in the area belongs to the Resins and Asphaltenes fraction, constituting an important part of the extracted oil, 63.72%, both fractions considered as resistant and with slow rates of biodegradation, at 80 days biodegradation rates were obtained Regarding the 9.2% Resin fraction and 42% for the Asphaltene fraction. This corroborates what has been indicated by other authors (Ercoli, 2001) (Infante, 2001), that all oil fractions are biodegradable.
Table 6. Concentration levels of the petroleum hydrocarbon fractions and related substances, expressed in mg / Kg.
|t = 0 days||16 870||20 120||25 660||39 320|
|t = 80 days||1 080||1 820||23 290||22 800|
On the other hand, in Table 6, a decrease in the concentration of saturated hydrocarbons is observed over time, because this fraction is made up of the substrates most susceptible to degradation by microorganisms (Figure 16). Regarding the content of aromatic hydrocarbons, it is also appreciated in the aforementioned figure, a decrease at the end of the analyzed period of 90.9%, a result that corresponds to the qualitative chromatographic profile of the F2 fraction.
The relatively low concentration levels of Resolved Saturated Hydrocarbons show the low paraffinic character of the contaminating oil in the treated soil.
Table 7 reports the concentrations of microorganisms found in the treatment area at different times. After assembly, the concentration of biodegradable microorganisms increased, reaching values of the order of 107, this being much higher than the minimum concentration established by Saracino and other authors, 2001, between 103 and 104, which may be due to the incorporation of residual sludge. of domestic wastewater treatment plants that have a high hydrocarbon degrading microbial load and are not assured until the studies are completed. In addition, it should be noted that although the concentration of the total microorganisms did not increase over time, values of the order of 109 were obtained, very favorable for these biodegradative processes.
Table 7. Behavior of Microbial Populations and CO2 Production.
|Total Heterotrophic O.M. count (CFU / g soil)|
HCs biodegradable (CFU / g soil)
(mg of CO2 / m2xh)
|t = 0||5.0 x 109||1.31 x 106||60, 15|
|t = 30||3.50 x 109||2.03 x 107||65,69|
|t = 80||1.25 x 109||2.50 x 107||71,37|
|t = 110||3.50 x 109||2.0 x 106||60.77|
|t = 180||5.45 x 10 9||3.02 x 10 6||66.23|
Figure 17 shows the behavior of CO2 production, observing typical patterns of biodegradative processes that indicate that the biodegradation of the petrolized solid waste is taking place, between 60 and 71 (mg of CO2 / cm2h), which are satisfactory for the bioremediation process, according to the authors' experiences in field-scale studies (Álvarez and others, 2005).
Conclusions and recommendations.
- The petrolized solid residue deposited in the exterior areas of the Birama Quarry presents high concentrations of fats and oils, and total petroleum hydrocarbons, with the most recalcitrant fractions to the biodegradative process, resins and asphaltenes predominant in its composition.
- The concentration of total aerobic and biodegrading bacteria present in the petrolized solid waste is above the range established to successfully carry out the Bioremediation process using the biostimulation technique.
- Low levels of nitrogen and phosphorus were found in the analyzed sample of residual sludge from the Taíno 1 domestic wastewater treatment plant belonging to Aguas Varadero.
- The high concentrations of total heterotrophic and biodegrading microorganisms present in the residual sludge from the Taino 1 sewage treatment plant make this waste an important source of contribution of microorganisms to the biological treatment of organic solid waste.
- The Bioremediation process applied to the petrolized solid waste disposed of in the area outside the pool of the Birama Quarry was satisfactory, reducing the levels of total oil hydrocarbons to values close to 1%, a limit recommended by the specialized literature for recovered soils. through biological processes, allowing new controlled incorporations of waste in the area.
- The chromatographic profile qualitatively shows the marked decrease in the aromatics fraction over time.
- Significant biodegradation rates were obtained for the Asphaltene fraction, 42%, considered resistant to the degradation process by the action of microorganisms.
- The levels of nitrogen and phosphorus in the residual sludge were sufficient for the development and growth of microorganisms in the hydrocarbon degradation process.
- The economic analysis of the applied bioremediation process reported low values per m3 of treated petrolized solid waste, resulting in a technology that is easy to apply and with significant economic benefits.
1. Apply the bioremediation process to treat the petrolized solid waste disposed of in the pool of the Birama Quarry and its controlled incorporation in the area where the treatment described here has been carried out.
2. Use residual sludge or digested sludge from domestic sewage treatment plants as a source of essential nutrients in the hydrocarbon Bioremediation process and thus provide an environmentally safe disposal of these wastes.
3. Conclude studies on the use of waste sludge from sewage treatment plants as a source of biodegradable microorganisms in the bioremediation process of soils contaminated by hydrocarbons and solid petroleum wastes.
By MSc. José Alfonso Álvarez González, Technical Gisela Novoa Rodríguez, Engineer Roberto Romero Silva, MSc. Ana C. Núñez Clemente, Dr. Miguel A. Díaz Díaz, Lic. Sandra Millar Palmer, Tech. Ahiram López Díaz, Tech. Isabel López Escobar, Tech. Cristina Laffita Rivera, Tech. Elsa Sánchez Sotolongo.
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The authors want to thank all the technical staff and workers of the company where this project was developed and especially Drs. Carmen Infante, Pablo Negrais, for their knowledge provided.