Showing 18 results for Pollutant
Mrs Saeideh Shahabi Rabori, Dr Sadegh Khalilian, Dr Seyed Habibollah Mosavi, Dr Hamed Najafi Alamdarlo,
Volume 0, Issue 0 (12-2024)
Abstract
Aim and Introduction
Today, the environment is considered as one of the most important pillars of sustainable development, and the development of other economic and social sectors depends on its sustainability and proper functioning. Environmental pollution has become one of the main challenges of countries. Environmental health is currently one of the most critical concerns of people and officials round the world. Almost all managers and decision makers believe that this national wealth should be protected not only for the current generation but also for future generations, since the pollutants caused by industries are highly costly and detrimental to health.
Active industries are one of the main sources of environmental pollution. One of the necessary conditions for economic progress and the introduction of extensive structural changes in economic and technological fields is industrialization and industrial development. In the production process, using production inputs whose main source is the environment, in addition to desirable outputs such as consumer goods, undesirable outputs such as environmental pollutants are also produced. If the number of outputs is not controlled and disproportionate, the losses from undesirable outputs will be greater than the benefits of desirable products in such a way that damages to the environment would be irreparable and sustainable development less likely to be achieved.
One of the most important concerns related to industrialization is the effects and environmental consequences of industrial activities. Therefore, achieving the necessary solutions to control such consequences is vitally important. Minerals are essential for human survival, but their extraction and processing are not environmentally friendly practices which contribute to problems such as soil erosion, air and water pollution. On the other hand, mineral sector is one of the largest energy consumers which has active contribution to air pollution and global warming. The main purpose of this study is to investigate the economic effects of Gol Gohar mine in Sirjan. For this purpose, it is intended to determine the type and amount of pollutants released from this complex, and also to determine the amount of the green tax of the complex as a solution to reduce pollution and examine the social welfare resulting from reducing pollution.
Methodology
In this study, the economic effects of environmental pollutants of Gol Gohar Iron Mine in Sirjan (Southeastern Iran), is investigated using the input distance function model from 2001 to 2022. Through calculating the shadow price of pollutants, a criterion for determining the green tax is determined, and then the amount of social cost resulting from the emission of pollutants is calculated.
The shadow price of the undesirable output is the cost that the producer must bear if they plan to reduce the production of the undesirable output. In fact, it can be interpreted as the marginal cost of reducing pollution for each producer. Therefore, the shadow price of the desirable output is considered positive and equal to the market price of that output, but the shadow price of the undesirable output must be estimated to be less than zero.
Findings
The products of Gol Gohar Iron Ore Complex in Sirjan, include granulated iron ore, iron ore concentrate and pelletized in the production process. The most greenhouse gases and air pollutants are related to carbon dioxide (CO2), sulfur oxides (Sox), nitrogen oxides (Nox) and particulate matter (SPM). According to the obtained results, the average shadow price for air pollutants in Gol Gohar complex for CO2, Sox Nox, and SPM was calculated as 11.15, 3,074.5, 5,529.62, and 1,875.62 rials per kilogram respectively. Moreover, the average total social costs resulting from the production of Gol Gohar Sirjan Complex was calculated as 92,710 billion Rials according to the amount of pollution produced over the period.
Discussion and Conclusion
The estimation of environmental costs is actually an introduction to providing solutions for internalizing and reducing environmental costs, using the input distance function model and the shadow price of environmental pollutants in the industrial and mineral complex of Gol Gohar, Sirjan. The title of the largest producer of iron ore in the country was calculated, and the social cost resulting from the emission of pollutants was also evaluated. Finally, in this study, solutions and mechanisms for reducing environmental costs have been proposed.
Considering that the ability to absorb pollutants by the environment is limited, the shadow price of pollutants, which represents their real social cost, should be taken into consideration. The damages should also be determined based on the shadow price of the pollutants. In other words, the amounts of pollutant emission should be calculated and while taking into account the allowed limit of pollutant emission and shadow prices, based on a legal plan, the environmental costs should be reimbursed. Taking such measures would surely require more studies and capable executive management system
Volume 2, Issue 3 (2-2019)
Abstract
Molecular imprinting is a novel technique for preparing specific absorbents with selective sites for binding to the target molecule. Molecularly imprinted polymers, because of their high selectivity and stability, low cost and easy methods of preparation, have been widely employed in separation procedures. In this study, we evaluated the synthesized electrospun imprinted membrane (MIM) as a specific sorbent for herbicide mecoprop (MCPP). The films were prepared using methacrylic acid (MAA) as functional monomer and polyethylene terephthalate (PET) as a main part of polymeric solution and in the presence of dichloromethane (DCM) and Trifluoroacetic acid (TFA) as the solvents. The template was extracted through washing, results in the free specific memory sites within the films. Then, the synthesized electrospun imprinted membrane (MIM) was evaluated as a specific sorbent for herbicide mecoprop (MCPP). The results showed that the solution with 20% w/v of PET was the optimal solution for electrospinning process and at all different MCPP/MAA molar ratios (1:2, 1:4. 1:6 and 1:8), MIM had higher removal ability for template molecule (p<0.05) compared to NIM. The template/monomer ratio of 1:4 had the best binding amount. We also investigated the capability of MIM to be used as sorbent for pesticide 2,4-D, that is, the analogue of the main template molecule and diazinon, that is, the pesticide with different structure to the template. In addition, we used synthesized MIM and NIM films to extract MCPP analyte from environmental aqueous samples (bottled water and groundwater) and the results indicated successful performance of MIM compared to NIN.
Volume 10, Issue 1 (2-2024)
Abstract
Background: Airborne biological agentsmaterials in hospitals, such as fungal i micro-colonies, play a significant role in life-threatening airborne infections in immunocompromised individuals. Thus, it is crucial to reduce airborne contamination and address the related several of its influencing factors. This study aimeds to evaluate indoor air quality (IAQ) in terms ofrelated to fungal contamination, the fungal genera contaminating the hospital rooms' air, and several factors that could influence IAQ in hospital rooms.
Materials & Methods: This environmental surveillance study was conducted in two rooms for onea year, andwith 288 air specimens were collected using thean active air sampling method equipped with chloramphenicol-supplemented Sabouraud Ddextrose Aagar. In addition to air samples, tTemperature, relative humidity, and occupants’ number were also recorded. The fFungal colony counts wereas recorded and converted using the Feller table. Furthermore, the fungi were identified based on macroscopic and microscopic characteristics.
Findings: The mean difference of isolated fungi between the twoboth rooms was statistically significant (p< 0.0001). Yeast, Penicillium spp, and Aspergillus spp. were the most predominant fungi. Both rooms hadwere observed to have room temperature and relative humidity above the national recommended levels (above 23 ˚C and 60%). However, the number of oOccupants' number in the room without HEPA filter was significantly correlated with airborne fungal contamination level in the room without a HEPA filter.
Conclusion: The level of airborne fungal contamination wasis significantly higher in the room without a HEPA filter. Yeast, Aspergillus spp., and Penicillium spp. were the most predominant fungi isolated fromin both rooms. Room temperature and relative humidity haddid not effect oninfluence the level of airborne fungal contamination level. The oOccupants' number in the room without a HEPA filter influenced airborne fungal contamination level.
Abdoulkarim Esmaeili, Robab Mohsenpour,
Volume 10, Issue 4 (1-2011)
Abstract
Regarding environmental importance and the lack of analytical methods for environmental policies, in this paper, shadow price for NOx and SOx emissions has been estimated for the Iranian electric industry. Input distance function is used for estimating shadow prices. The estimated shadow prices have revealed that the cost of Iranian electric industry for reducing one KG of NOx and Sox is 14991 and 17687 Rials, respectively. Estimated shadow prices in this study are greater than the amount offered by EPO (Environment Protection Organization) and World Bank. So it is recommended that any fine should be taken according to the emission shadow price.
Volume 11, Issue 2 (6-2020)
Abstract
The present study was accomplished to purify and biochemically characterize the phenol-degrading enzyme from the bacteria existed in petroleum-contaminated soils. The catechol 1, 2 dioxygenase was extracted from
Aneurinibacillus migulanus Isolate ZNU05 and purified using Q-Sepharose ion exchange chromatography column. The enzyme activity was examined under different pHs (ranged from 4 to 9), at different temperatures (ranged from 20 to 70˚C), in the presence of various metal ions chloride salts (Ca
2+, K
+, Mn
2+, Co
2+, Zn
2+, Mg
2+, Cu
2+ and Na
+), and with various solvents (ethanol, ethyl acetate, petroleum ether, acetonitrile, N-amyl alcohol
, N-hexane, and toluene). In addition, the enzyme activity was investigated using different substrates such as
phenol, catechol, benzoic acid, pyrogallol and α-naphtol. SDS-PAGE analysis indicated that there was a single-band protein with a molecular weight of approximately 40 kDa. The catechol 1, 2 dioxygenase had a maximum activity at temperature 30˚C at pH 8.5. Moreover, the catalytic activity of the enzyme was increased in the presence of cobalt and zinc ions as well as organic solvent of amyl alcohol, while it was decreased or inhibited in the presence of the other metal ions and organic solvents used. Among different substrates on enzyme activity, catechol was the most favorable for the enzyme, so that, the
Vmax and
Km were 8.959 U/mg and 4.992 µg/mL for the substrate, respectively.
Volume 13, Issue 2 (5-2013)
Abstract
In this paper, pollutants flows coming out of stacks or cooling towers with different outlet shapes have been numerically studied. The effects of exhaust outlet on plume rise, and the pollutant dissipation are investigated. To simulate the flow turbulence, realizable k – ε model is employed for the case of a stack flow with more than one exhaust outlet on the influence of wind condition. The plume rise and dissipation of pollutant are depending on the direction of the wind and the shape of exhaust outlet. Depending on wind direction and shape of exhaust outlet, higher or lower levels of plume rise can be obtained with various kind of pollutant dissipation. These changes are due to the influence of high pressure upstream and low-pressure downstream flow fields of outlet from stacks on the counter vertex rotating pair. The maximum concentration and dissipation of pollutant for various wind directions and output configurations are examined.
Volume 14, Issue 6 (9-2014)
Abstract
The present paper investigated the capability of various non-linear k–ε models for predicting flow field and pollutant dispersion around a cubical model building with a stack vent located on its roof center within the turbulent boundary layer. One quadratic model proposed by Nisizima and Yoshizawa, and two cubic models, proposed by Lien et al. and Ehrhard and Moussiopoulos were examined by comparing their simulation results with the wind tunnel data and standard k–ε model. All the computations were performed by using the self-developed object-oriented C++ programming in OpenFOAM CFD package, which contains applications and utilities for finite volume solvers. The standard k–ε model provided inadequate results for the flow field, because it could not reproduce the basic flow structures, such as reverse flow on the roof. By contrast, the non-linear models were able to predict anisotropic stresses and correctly showed the dominant stress over the roof to be the streamwise Reynolds stress. The non-linear models were able to predict the concentration field better than the SKE model due to inclusion of the quadratic and cubic terms. Among the RANS models, the Ehrhard model showed the best agreement with the experimental data. It was shown that concentrations predicted by all turbulence models were less diffusive than those of the experiment, although the non-linear k–ε models have reduced this difference.
Volume 15, Issue 9 (11-2015)
Abstract
In present paper, the effect of combined cooling, heating and power generation systems(CCHP) in the reduction of pollutants emission have been investigated and a hotel with 80 rooms in Zahedan have been selected as case study , also gas engine (With part-load operation) as prime mover for design CCHP system. In this work is assumed that sell electricity to grid is possible. At the first phase, optimization for access to maximum reduce Pollutants emission have been done, at the other phase, a multi-criteria function has been introduced and the optimization process, with Percentage of Relative Annual Benefit (PRAB) has been investigated and the results of these two phases, have been compared together. Results show, CCHP systems have a high effect in reduce environmental pollutants emission CO, CO2 and NOx, as the percent reduce pollutants emission is positive in an extensive range of nominal power of gas engine. Also results show for access to maximum reduce pollutants emissions , CO2, CO and NOx, annual benefit as multi-ceritria objective function a gas engine with nominal power 2050kW is needed; in this case in addition to the most annual benefit also have a good effect for reducing Pollutants emission. In the end, the effect of the number of prime mover as designing parameter assessed with increase from one into two and three numbers. Results show increasing prime mover, cause decrease Relative Annual Benefit and pollutants emission.
Volume 16, Issue 7 (9-2016)
Abstract
Air staging is defined as the supply of inadequate air from the primary stage to the reaction zone, and the completion of the air supply through the next stage or stages. This study is concerned with the optimization of the air staging system of a burner with two air inlets and one fuel (natural gas) inlet with the help of numerical modeling. The equivalence ratio of the primary air (with the assumption of a fixed total air mass flow rate), and the distance between the two air inlets constitute the design variables of the problem. In the previous research works, the air staging technology has been mainly employed as a method to reduce the emission of NO. However, in the current study, in addition to the emission of NO, the emissions of CO and soot, and radiative heat transfer from the flame are considered as the objective functions. The results show that increasing the level of air staging (or the equivalence ratio of the primary air) has contradictory effects on the objective functions so that, as positive influences, it increases the radiative heat transfer from the flame and decreases the emission of NO, and as negative effects, it increases the emission of both CO and soot. The results also indicate that when all the previously mentioned objectives are considered simultaneously, the optimal case, which is selected based on the Pareto front concept, is the case in which the primary air is about 20% of the theoretical air.
Volume 17, Issue 2 (3-2017)
Abstract
Estimating indoor air pollutants to ensure the air quality is very important. In this study, a conventional residential space is numerically simulated in order to investigate the behavior of pollutants. Using the numerical results and the experimental results of other references, proposed the analytical relation to estimate the concentration of CO2 in term of factors such as CO2 produced by breathing residents or combustion equipment, the volume of space and ventilation rate. The results of the analytical relation are full compliance with experimental and numerical results and it can be used to estimate indoor air quality. Proposed relation can be used in all the same cases.
Ehsan Taheri, Hossein Sadeghi, Abbas Assari Arani,
Volume 17, Issue 3 (9-2017)
Abstract
The ecosystem is a fundamental pillar of human life, which has been changed due to the progress and development of the world. The emission of air pollutants is a key factor in environmental degradation. Air pollutants impose the so-called "degradation costs" on different sectors, which these costs are not included in official calculations. Consumption of energy carriers is the main cause of air pollutants emissions in Iran. Therefore, this research seeks to examine the degradation costs of air pollutants emitted by the use of energy carriers in Iran. One way to reduce the emissions of air pollutants and their degradation costs is to impose tax on the consumption of energy carriers. This study considers a scenario for raising the price of energy carriers to the level of FOB price of Persian Gulf. For this purpose, the standard computable general equilibrium model of Lofgren et al () is used. The statistical basis of the CGE model is the 2006 social accounting matrix (SAM). The statistical data on energy consumption and emissions of air pollutants are derived from the energy balance sheets over the period 2006-2012. In addition, economic sectors are divided into 25 sections according to the ISIC classification. Degradation cost in the baseline scenario is equivalent of 14.43% of GDP (at constant prices) in 2006, which by applying the scenario for increasing the price of energy carriers, this cost declines by 23% and amounts to 10 percent of GDP. Results also reveal that the road transportation and electricity sectors experience the greatest reductions in degradation cost.
Volume 17, Issue 4 (11-2017)
Abstract
The petroleum refineries, water are used for different purposes, such as extraction of contaminants. Some of these pollutants such as petroleum and Methyl Tertiary Butyl ether (MTBE) can be noted that have less biodegradability than other organic compounds. Discharge of these pollutants into water, and the presence of them in drinking water make huge environmental concerns.
A sequencing airlift reactor (SBR) along with an internal riser is called sequencing batch airlift reactor (SBAR); it has a similar structure to SBR and purifies wastewater with a certain temporal cycle in a single reactor. The SBAR system, which is used along with granules to treat wastewater, is known as granule sequencing batch airlift reactor (GSBAR). Using this system for biodegrading requires a high concentration of biomass (aerobic granules.
In recent years, several studies have been conducted on the use of aerobic biogranules. Mousavi et al., examined the removal of phenol with an initial concentration of 1000 mg/L from saline wastewater using GSBAR with aerobic granules 2 mm in size. The results indicated that 99% of phenol was removed. Bao et al., studied the effect of temperature on the formation of aerobic granules and on the removal of nutrients by SBAR system. The granules had an average diameter of 3–4 mm, density of 1.036 g/mL, sludge volume index of 37 mL/g, and sedimentation rate of 18.6–65.1 cm/min. The input load rate of COD, NH4–N, and PO4–P was 1.2–2.4, 0.122, and 0.012–0.024 kg/m3/day, respectively and the removal efficiency at low temperatures was 90.6–95.4, 72.8–82.1, and 95.8–97.9%, respectively. Taheri et al., examined the formation of aerobic granules in SBR for treating saline wastewater. In this study, the granules were 3–7 mm in size, had a fall speed of 0.9–1.35 cm/s, and density of 32-60 g/L. Using aerobic granules with a diameter of 1–2 mm to biologically restore 2, 4-di-chlorophenol with an initial concentration of 4.8 mg/L, Wang et al., achieved the removal efficiency of 95% and 94% for COD and di-chlorophenol, respectively. Siroos Rezaei et al. reported that COD removal efficiency of synthetic wastewater was 95% with the glucose carbon source in six 4-h cycles with a loading rate of 1500 mg/L in SBAR system using aerobic granules. The new granules had different diameters in the range of 0.5–5 mm, high sedimentation ability, and SVI of 100 mL/g. Ghaderi et al., investigated the performance of the biofilm reactor and SBR in removing formaldehyde from wastewater. The results revealed that removal efficiency of CODs less than 200 mg/L was 100% and removal efficiency of CODs between 200–450 mg/L was 90% after 48 h.
The aim of this study was evaluating the ability of SBAR system in quick produce of granules and achieving high removal of petroleum and MTBE in a short time. For this purpose, 2 similar SBAR systems with Circular cross-section were used. Outer Cylinder's diameter and length was respectively 8cm and 110 and the internal riser's diameter and length was respectively 4 cm and 90 cm. In the first system (R1) petroleum was treated in 6 hours and in the second system (R2) MTBE wastewater was treated in 4 hours. In COD equivalent to 600 mg/L, the removal efficiency of R1 and R2 were equal to 81.1 and 84.2%. These values were respectively 82.8 and 90% in COD equivalent 500 mg/L. Consider to granules changes, optimal COD was respectively equivalent to 600 and 500 mg/L in R1 and R2. By reducing retention time to 5 and 3 hours in R1 and R2, removal efficiency of pollutants in optimal COD of each system was respectively 77.8 and 90 %. The first granules were observed in the seventh day of operating system. During this period, the size of the granules increased to 1.3 and 0.6 mm in R1 and R2. Density and velocity of the granules were in the range of 0.0252-1.1998 gr/mL and 3.02-3.32 cm/s in R1 and 0.05-0.06502 gr/mL and 0.4-0.9 cm/s in R2. SVI was in the range of 42-65 mL/g, pH and DO was in the range of 6.8-7.2 and 2-6 mg/L and ORP was always above 100 mV.
Volume 17, Issue 6 (8-2017)
Abstract
In recent years, increased pollution and traffic in urban has caused the development of underground transport. One conventional approach for urban tunnel ventilation is construction mid-tunnel shafts. These shafts are usually located in high-density urban areas and emissions from them can be harmful for the residents of adjacent buildings. The geometry of these shafts is determined so far based on taste and only for the purpose of compliance standards criteria for tunnel indoor air. In this paper, pollutant dispersion from different and conventional geometries of mid-tunnel shafts with the assumption of a taller downstream building was investigated for the first time. The results can help to reach a better design of these shafts and surrounding buildings to have healthier air for residents of buildings. For this purpose, simulations were done by OpenFOAM. Reynolds-Averaged Navier-Stokes equations method and standard k-ε model were used in simulations. The results showed for the same exhaust velocity, the effect of rectangular and square configuration on front wall depends on dimension of the side which is perpendicular to wind direction. For the exhaust velocity less than 6 m/s, the downstream building prevents pollutants to reach higher altitude and the amount of pollutants will be increased around 100 percent and for exhaust velocity of more than 6m/s, increasing velocity will cause to less changes in pollutant concentration at lower level. In addition, the results showed that exhaust velocity has more effect than geometry configuration on pollutant dispersion and this influence will be decreased by increasing the velocity.
Volume 18, Issue 6 (10-2018)
Abstract
Now a days gas turbines are widely used in the transportation and energy industry. According to Combustion of fossil fuels in these engine, environmental concerns have increased due to production of nitrogen oxides and carbon monoxide. Various methods have been offered to reduce the emission of pollutants. One of these methods is adding steam or water to the combustion chamber to reduce the flame temperature. Different methods can be applied to add steam to the combustion chamber, in this study, the steam is added to the diffuser and premixed with air into the combustion chamber. Steam addition influences the combustion process inside the combustion chamber, which should be considered during the combustion chamber design process. Therefore, a model for the conceptual design of the chamber geometry and the effect of adding steam on it will be presented. For this purpose, the data from an actual combustion chamber will be used to compare results of geometry design by using this model and to study the influence of steam on the chamber geometry. To investigate the combustion chamber performance, the chemical reactor network method for combustion modeling will be used. First, with this procedure an annular conventional combustion chamber will be modeled without steam addition and the results of this method will be compared with the actual data of this combustor. Then the effect of adding steam on the performance will be investigated. The study will show adding steam is an effective way to reduce the flame temperature and emission of pollutants.
Volume 19, Issue 2 (2-2019)
Abstract
Controlling the gas turbine emissions has led the manufacturers to use new technologies. Nitrogen oxides (NOx) are one of the major pollutants of gas turbines with natural gas as fuel. Thermal NOx is the main cause of NOx formation in gas turbines at high temperatures. So, water injection can be useful in reducing the NOx emission. In addition to NOx reduction, water injection causes an increase in carbon monoxide emission and damage to combustion chamber. Therefore, it is desirable to find the optimum amount of water injected to the combustion chamber to meet the regulations. To find the optimal water mass flow rate, we numerically investigated the combustion inside the chamber for full load and part load before and after water injection. Then, the effect of water injection at different flow rates was studied to obtain optimal water flow rate. The results showed that for the full load, the optimal water flow rate was 100% of the fuel flow rate and the upstream pressure of the feed water system was 24.45 bar. For the part load (fuel flow rate equals to 75% of the full load), the optimum water injection rate is 80% of the fuel flow rate. In this case, the pressure required for water injection is about 16.5 bar. Results also show that the change in water temperature in the range of 10-80˚C has no significant effect on NOx formation and water can be injected at the ambient temperature.
Volume 19, Issue 3 (3-2019)
Abstract
Waste heat recovery systems, which make use of waste sources for their input energy, have considerable importance in industry since they utilize streams, which will be disposed to nature if not employed. Ship’s engines are one of the places, where a large amount of energy is wasted in different forms. In the present article, the idea of making use of these loss streams and consequently producing useful power in the outlet is proposed in the form of two systems. In the first system, the only stream of exhaust gases is utilized, while in the second system, the jacket cooling water is used together with the engine exhaust gases. Screening in the working fluids is conducted in order to select appropriate fluids, which have suitable characteristics in the physical, safety, and environmental aspects. The analyses indicate that using R600a presents the highest net power output, which reaches to the value of about 575 kW at the most. Comparison of the two introduced systems shows that preheating the working fluid by the jacket cooling water makes the better operation of the system and the power output is increased up to about 31-58% in different fluids. The lowest payback period in the systems is achieved through the use of R600a as the working fluid, which is about 3.48 year in the second system.
Volume 19, Issue 12 (12-2019)
Abstract
Co-firing of biomass and fossil fuels in industrial furnaces is a suitable way to reduce the environmental impact from human activities, with acceptable investment. In this paper, the results of numerical simulation co-firing of sulfide concentrates and three auxiliary fuels including gasoil, kerosene and sawdust biomass are compared in the flash furnace copper smelting. For modeling of turbulent flow and combustion, RNG, k-ε model and probability density function model (pdf) have been used, respectively. This study has been carried out to investigate the furnace temperature and combustion pollutants distribution. The numerical simulation results show that the flame temperature resulting from the combustion of diesel fuel and sawdust as auxiliary fuel is the highest and lowest, respectively. In biomass combustion, despite that the flame temperature is low, but the NOx mass fraction increases because there is nitrogen in the sawdust chemical composition. Also in sawdust combustion that the oxygen content is high, the SO2 and SO3 sulfur pollutants increase in the high temperatures regions of the furnace and the lower temperature of the auxiliary fuel burner, respectively. Because SO2 is formed at high temperatures (> 1273K) and oxygen-rich and SO3 species is produced at relatively low temperatures with excess oxygen. The amount of CO emissions in sawdust combustion is much lower than the amount of combustion of diesel and oil.
Volume 20, Issue 6 (6-2020)
Abstract
Considering the disadvantages of gasoline and natural gas as mono-fuel in SI engines has made the researchers improve the performance and reduce the pollutant as the advantages of the application of dual-fuel engines. On the other hand, lean-burn in the engine may lead to reduced pollutants. In the present study various mixtures of gasoline and natural gas with the gasoline as the dominant fuel, including 100, 87.5, 75 and 62.5% in weight-base gasoline and the rest natural gas (respectively named as G100, G87.5, G75, G62.5) in lean-burn condition with 0.9 as the equivalence ratio are investigated. At 1800rpm and 10 compression ratio, cylinder pressure variations of 350 successive cycles of each mixture were recorded using a single-cylinder research engine. First of all, the raw data were processed and the optimized knock-free advance for each individual mixture was determined. Later on, the performance of all four mixtures in the corresponding optimized advance was explored. The results revealed that by increasing the amount of natural gas in the mixture, the CO pollutant reduced however the amount of HC initially increased which was followed by a decreasing trend. The amount of NOx had a direct relation with the appearance of the natural gas. In the lean-burn condition, a better performance was observed for G75 in comparison with G100 and the other mixtures.