Radiological hazards of TENORM in the wasted petroleum pipes

Disposal petroleum pipes containing sludge and scale as a technically enhanced natural occurring radioactive material (TENORM) leads to internal and external radiation hazards and then a significant radiation dose to the workers. In order to contribute to a future waste management policy related to the presence of TENORM in the disposal sites of wasted petroleum pipes, scale and sludge as TENORM wastes are collected form these disposal pipes for radiometric analysis. These pipes are imported from onshore oilfields at south Sinai governorate, Egypt. The highest mean ²²⁶Ra and ²²⁸Ra concentrations of 519 and 50 kBq/kg respectively, were measured in scale samples. Sludge lies within the normal range of radium concentration. The average absorbed dose caused by the exposure to the wasted pipes equal to 4.09 μGy h⁻¹ from sludge and 262 μGy h⁻¹ from scale. This is much higher than the acceptable level of 0.059 μGy h⁻¹. Due to radon inhalation, important radon related parameters are calculated which advantage in internal dose calculation. Fairly good correlation between real radium content and radon exhalation rate for sludge samples is obtained. The hazards from sludge come from its high emanation power for radon which equal to 3.83%. The obtained results demonstrate the need of screening oil residues for their radionuclide content in order to decide about their final disposal.     

Radon, helium and CO2 measurements in soils overlying a former exploited oilfield, Pechelbronn district, Bas-Rhin, France

The Pechelbronn oilfield (Rhine Graben, France), where mining activity ended in the 1960s, has been used for waste disposal for twenty years. Since the wastes are varied, work is underway to identify the discharged materials and their derivatives, as well as to locate and quantify potential discharge sites. Two major goals were assigned to the present work. The first was to identify or refine the location of hidden structures that could facilitate gas emanation up to the surface, by studying soil gas concentrations (mainly ²²²Rn, CO₂, CH₄ and helium) and carbon isotope ratios in the CO₂ phase. The second was devoted to examining, from a health and safety viewpoint, if the use of the oilfield as a waste disposal site might have led to enhanced or modified gas emanation throughout the area.It appeared that CO₂ and ²²²Rn evolution in the whole area were similar, except near some of the faults and fractures that are known through surface mapping and underground observations. These ²²²Rn and CO₂ anomalies made it possible to highlight more emissive zones that are either related to main faults or to secondary fractures acting as migration pathways. In that sense, the CO₂ phase can be used to evaluate ²²²Rn activities distant from tectonic structures but can lead to erroneous evaluations near to gas migration pathways. Dumping of wastes, as well as oil residues, did not appear to have a strong influence on soil gaseous species and emanation. Similarly, enhanced gas migration due to underground galleries and exploitation wells has not been established. Carbon isotope ratios suggested a balance of biological phenomena, despite the high CO₂ contents reached. Other monitored gaseous species (N₂, Ar, H₂ and alkanes), when detected, always showed amounts close to those found subsurface and/or in atmospheric gases.     

Measurements of radiation level in petroleum products and wastes in Riyadh City Refinery

Recent concern has been devoted to the hazard arising from naturally occurring radioactive materials (NORM) in oil and gas facilities. Twenty-seven petroleum samples were collected from Riyadh Refinery. Fourteen samples were products and 13 were waste samples; three of them were scale samples and 10 were sludge samples. The specific radioactivities of (238)U, (232)Th, (226)Ra, (224)Ra, (40)K, and (235)U for all samples were determined using high-resolution gamma-ray spectrometry. The radium equivalent activity, radiation hazard indices and absorbed dose rate in air for all waste samples were estimated. The radon emanation coefficient of the waste samples was estimated. It ranged between 0.574 and 0.154. The age of two scale samples was determined and found to be 2.39 and 3.66 years. The chemical structure of the waste samples was investigated using X-ray florescence analysis (XRF) and Mg, Al, Si, S, Cl, Ca and Fe were found in all samples. From this study, it was noticed that the concentrations of the natural radionuclides in the petroleum wastes were higher than that of the petroleum products.     

Radiological impact of coal-fired power generation

A radiological impact assessment was carried out at the 4000 MW Nanticoke Thermal Generating Station on the north shore of Lake Erie and at an ash disposal site in Metropolitan Toronto, both operated by Ontario Hydro. Analyses were performed on feed coal, fly ash and bottom ash and on samples of air filters, precipitation, water, soil and vegetation in the vicinity of the generating station. The measured radionuclide levels in the vicinity of the generating station showed no evidence of enhancement from station emissions. There were no indications that leaching of radionuclides or emanation of radon gas from ash disposal sites would be a problem. There was evidence, however, of higher radionuclide concentrations on the finer ash particles. Furthermore, the use of fly ash in building materials could lead to enhanced radiation levels. Atmospheric dispersion and radiation dose calculations were also carried out. Predicted concentrations in air were all less than 1% of background values. The committed dose equivalent from one year of operation was estimated to be 0·27 μSv at the site boundary and 0·11 μSv at 10 km east of the site.     

Evaluation of Brasilia wastewater sludge as a biomass resource for the production of energy by gasification simulation

This work evaluated the sludge potential of the Wastewater Treatment Plant (ETA) in the city of Brasília to be used as a fuel by gasification. It is known that ETA sludge is a significant environmental liability, since current legislation restricts its final disposal. For this, the chemical characterisation of ETA sludge was performed by immediate and elemental analysis. No traces of heavy metals were observed, and the moisture (ω) and ash contents were 31.17 and 51.77%, respectively, different from those already reported in the literature because the composition depends on the water treatment technology employed. The gasification process was numerically simulated; once dry, it constitutes a residue with an energy content (HHV) of 22.4498 MJ kg^?1, comparable with other types of biomass currently used for large-scale energy generation by thermochemical processes (e.g. agricultural residues, wood and sugar cane bagasse). For the numerical simulation with an equivalence ratio (Φ) near 3, higher concentrations of CO and H₂ can only be achieved with ω lower than 15%. The results showed that gasification can be an attractive option for the disposal and use of a renewable waste resource, such as ETA sludge, in an environmentally safe way, and it is allowed by local legislation.     

Airborne gamma survey of the historic Sleisbeck mine area in the Northern Territory, Australia, and its use for site rehabilitation planning

An airborne gamma-survey provided information about the extent of radioactive contamination around the historic Sleisbeck mine. Quickbird satellite data were acquired to relate airborne measurements to land cover features. Enhanced equivalent uranium (eU) levels were found to be confined to the mine and low grade waste rock dumps. The average terrestrial background radiation dose rate estimated from the airborne gamma survey data was 0.10-0.14 microGy h(-1) while the area around the mine exhibited a maximum of approximately 2.3 microGy h(-1), but measurements on the ground indicate that this maximum is exceeded in some localized areas. Rehabilitation of the site is likely to result in a threefold reduction in radiation doses to people accessing the area.     

Mechanical performance and capillary water absorption of sewage sludge ash concrete (SSAC)

Disposal of sewage sludge from waste water treatment plants is a serious environmental problem of increasing magnitude. Waste water treatment generates as much as 70 g of dry solids per capita per day. Although one of the disposal solutions for this waste is through incineration, still almost 30% of sludge solids remain as ash. This paper presents results related to reuse of sewage sludge ash in concrete. The sludge was characterised for chemical composition (X-ray flourescence analysis), crystalline phases (X-ray diffraction analysis) and pozzolanic activity. The effects of incineration on crystal phases of the dry sludge were investigated. Two water/cement (W/C) ratios (0.55 and 0.45) and three sludge ash percentages (5%, 10% and 20%) per cement mass were used as filler. The mechanical performance of sewage sludge ash concrete (SSAC) at different curing ages (3, 7, 28 and 90 days) was assessed by means of mechanical tests and capillary water absorption. Results show that sewage sludge ash leads to a reduction in density and mechanical strength and to an increase in capillary water absorption. Results also show that SSAC with 20% of sewage sludge ash and W/C = 0.45 has a 28 day compressive strength of almost 30 MPa. SSAC with a sludge ash contents of 5% and 10% has the same capillary water absorption coefficient as the control concrete; as for the concrete mixtures with 20% sludge ash content, the capillary water absorption is higher but in line with C20/25 strength class concretes performance.     

Characterization of the TE-NORM waste associated with oil and natural gas production in Abu Rudeis, Egypt

The present study was conducted to characterize the Technically Enhanced Naturally Occurring Radioactive Materials (TE-NORM) waste generated from oil and gas production. The waste was characterized by means of dry screening solid fractionation, X-ray analysis (XRF and XRD) and gamma-ray spectrometry. Sediment of the TE-NORM waste was fractionated into ten fractions with particle sizes varying from less than 100 microm to more than 3 mm. The results showed that the TE-NORM waste contains mainly radionuclides of the 238U, 235U and 232Th series. The mean activity concentrations of 226Ra (of U-series), 228Ra (of Th-series) and 40K in the waste samples before fractionation (i.e. 3 mm) were found to amount to 68.9, 24 and 1.3 Bq/g (dry weight), respectively. After dry fractionation, the activity concentrations were widely distributed and enriched in certain fractions. This represented a 1.48 and 1.82-fold enrichment of 226Ra and 228Ra, respectively, in fraction F8 (2.0-2.5 mm) over those in bulk TE-NORM waste samples. The activity ratios of 238U/226Ra, 210Pb/226Ra, 223Ra/226Ra and 228Ra/224Ra were calculated and evaluated. Activity of the most hazardous radionuclide 226Ra was found to be higher than the exemption levels established by IAEA [International Atomic Energy Agency, 1994. International Basic Safety Standards for the Protection against Ionizing Radiation and for the Safety of Radiation Sources. GOV/2715/94, Vienna]. The radium equivalent activity (Ra-eq), radon (222Rn) emanation coefficient (EC) and absorbed dose rate (Dgammar) were estimated and these are further discussed.     

Radon exhalation of cementitious materials made with coal fly ash: Part 1--scientific background and testing of the cement and fly ash emanation

Increased interest in measuring radionuclides and radon concentrations in fly ash, cement and other components of building products is due to the concern of health hazards of naturally occurring radioactive materials (NORM). The current work focuses on studying the influence of fly ash (FA) on radon-exhalation rate (radon flux) from cementitious materials. The tests were carried out on cement paste specimens with different FA contents. The first part of the paper presents the scientific background and describes the experiments, which we designed for testing the radon emanation of the raw materials used in the preparation of the cement-FA pastes. It is found that despite the higher (226)Ra content in FA (more than 3 times, compared with Portland cement) the radon emanation is significantly lower in FA (7.65% for cement vs. 0.52% only for FA).     

Natural radioactivity and radiation exposure in the high background area at Chhatrapur beach placer deposit of Orissa, India

A high natural background radiation area is reported for the Chhatrapur beach placer deposit of Orissa state, on the southeastern coast of India, due to the presence of radiogenic heavy minerals. The average activity concentrations of radioactive elements 232Th, 238U and 40K were measured by gamma-ray spectrometry using a HPGe detector, and found to be 2500 +/-1850, 230 +/- 140 and 120 +/- 35 Bq kg-1, respectively, for the bulk sand samples. The absorbed gamma dose rates in air due to the naturally occurring radionuclides varied from 375 to 5000 nGy h-1, with an average value of 1625 +/- 1200 nGy h-1. The external annual effective dose rate of the region ranged from 0.46 to 6.12 mSv y-1, with an average value of 1625 +/- 1200 mSv y-1. The absorbed gamma dose rate levels of Chhatrapur beach area were similar to the monazite sand-bearing high background radiation areas of southern and southwestern coastal tracts of India and other similar areas of the world. The major contributors to the enhanced level of radiation are monazite and zircon sands.     

Measurements of radon around closed uranium mines

There are several waste rock yards at closed uranium mines around Ningyo-toge, in the Western Honshu Island of Japan, and measurements of radon were carried out by both the passive method and the sampling method around these yards. As comparatively high radon concentrations were observed in two districts through routine measurements, more detailed measurements were made by the passive method in these districts. The impact of radon emanation from the waste rock yards was small for both residential districts and around these yards when considering the natural background level of radon. In addition, by simultaneous continuous measurements of radon and its progeny at two locations, it was estimated that the effective dose caused by the representative uranium waste rock yards was less than the public effective dose limit of 1 mSv year(-1) at the fenced boundary of the waste rock site.     

Significant radioactive contamination of soil around a coal-fired thermal power plant

Soil samples were collected around a coal-fired power plant from 81 different locations. Brown coal, unusually rich in uranium, is burnt in this plant that lies inside the confines of a small industrial town and has been operational since 1943. Activity concentrations of the radionuclides 238U, 226Ra, 232Th, 137Cs and 40K were determined in the samples. Considerably elevated concentrations of 238U and 226Ra have been found in most samples collected within the inhabited area. Concentrations of 235U and 226Ra in soil decreased regularly with increasing depth at many locations, which can be explained by fly-ash fallout. Concentrations of 235U and 226Ra in the top (0-5 cm depth) layer of soil in public areas inside the town are 4.7 times higher, on average, than those in the uncontaminated deeper layers, which means there is about 108 Bq kg(-1) surplus activity concentration above the geological background. A high emanation rate of 222Rn from the contaminated soil layers and significant disequilibrium between 238U and 226Ra activities in some kinds of samples have been found.     

The economics of handling refinery sludges

Methods of handling sludges generated from normal refinery operations are evaluated to determine the costs of alternative disposal methodologies. Sludges generated from several areas in the refinery are classified as (1) sludges from which oils may be recovered; (2) other oily sludges from which oils cannot be recovered; and (3) biological sludges. Methodologies for handling these sludges are reviewed based on previous experience. The economics of handling a representative combination of biological and oily sludges from the refinery are evaluated considering three disposal options: Alternative I in which the sludge would be dewatered using pressure filtration followed by landfill disposal of the sludge cake; Alteration II in which vacuum filtration was employed for sludge dewatering followed by sludge disposal in a landfill; and Alternative III in which the sludges were disposed of by landfarming. Costs are presented for centrifugation of oily sludges and incineration as a final disposal alternative.     

Radioactivity and elemental analysis in the Ruseifa municipal landfill, Jordan

In this study, a low background gamma-ray spectrometer based on a Hyper Pure Germanium detector was used to determine the activity concentrations of natural radionuclides in soil samples from various locations within the Ruseifa municipal landfill in Jordan. The chemical composition of the samples was also determined using a Wavelength Dispersive X-Ray Fluorescence Spectrometer. The maximum and minimum annual outdoor effective doses were found to be 103 and 36muSva(-1) in the old landfill and Abu-Sayaah village, respectively. The annual outdoor effective dose at the recent landfill site was found to be 91muSva(-1). The annual effective dose equivalents from outdoor terrestrial gamma radiation at the old landfill and the recent landfill were higher than the typical worldwide value of 70muSva(-1). Thus, some remediation of the soils on both old and recent landfills should be considered before any development for public activities. This could be achieved by mixing with clean soil from areas which are known to have lower radiation background. The concentration of heavy metals Zn, Cr, and Ba in the three sites included in this study were found to be higher than the background levels in the soil samples of the control area (Abu-Sayaah village). The enrichment factors for the above three elements were calculated and found to be: complex building site: Zn=2.52 and Ba=1.33; old landfill site: Cr=1.88, Zn=3.64, and Ba=1.26; and recent landfill site: Cr=1.57, Zn=2.19, and Ba=1.28. There was a strong negative correlation between the concentrations of the metallic elements (Mg, Al, Mn, Fe and Rb) and the concentrations of Zn, Ba, and Cr. Moreover, a strong positive correlation was found between Zn, Ba, and Cr. Thus these elements were enriched in the solid waste.     

Estimation of 222Rn release from the phosphogypsum board used in housing panels

Phosphogypsum board is a popular construction material used for housing panels in Korea. Phosphogypsum often contains (226)Ra which decays into (222)Rn through an alpha transformation. (222)Rn emanated from the (226)Ra-bearing phosphogypsum board has drawn the public concern due to its potential radiological impacts to indoor occupants. The emanation rate of (222)Rn from the board is estimated in this paper. A mathematical model of the emanation rate of (222)Rn from the board is presented and validated through a series of experiments. The back diffusion effect due to accumulation of (222)Rn-laden air was incorporated in the model and found to have a strong impact on the (222)Rn emanation characteristics.     

Radon emanation from NORM-contaminated pipe scale and soil at petroleum industry sites

Radon-222 emanation fractions were determined for barite scale deposits associated with petroleum production tubing and soil contaminated with naturally occurring radioactive material (NORM). Samples were analyzed for 226Ra concentration, the results of which were used to calculate the 222Rn emanation fraction for the sample. An important parameter determining the overall Rn activity flux from a solid medium, 222Rn emanation fraction represents the fraction of 222Rn produced that enters the interconnected pore space within a medium contaminated with 226Ra before the 222Rn undergoes radioactive decay. The primary objective of the study was to determine whether 222Rn emanation fractions from pipe scale and soil from petroleum production sites are similar to those of uranium mill tailings. Pipe scale samples were collected at four sites representing a wide geographical area, and consisted primarily of barite scale where Ra atoms have replaced a fraction of the Ba within the crystal lattice of the scale. Soil samples were collected at five sites, from areas exhibiting elevated surface gamma exposure rates indicating the presence of NORM. For comparison, 226Ra concentrations and 222Rn emanation fraction were also determined for uranium mill tailings samples provided from a site in Utah. Although 2226Ra concentrations from pipe scale samples were similar to those found in uranium mill tailings, 222Rn emanation fractions from scale were generally lower. Emanation fractions from each data set were statistically different from those of mill tailings (p < or = 0.01). The differences are probably due to physical differences between the two media and to the method by which the Ra is deposited in the material. Radon emanation from soils was extremely variable owing not only to differences in physical and chemical soil properties, but also to the means by which NORM has entered the soil. Although additional emanation measurements from other sites are needed, the data collected at these sites indicate that regulations intended to protect human health from 222Rn inhalation should consider the type and properties of the medium in which the NORM is contained, rather than relying strictly on concentrations of the parent 226Ra.     

Introduction of a recycling system for sustainable municipal solid waste management: a case study on the greater Banjul area of the Gambia

This research proposes for the introduction of a recycling system in the Gambia to enhance sustainable municipal solid waste management. Poor infrastructures, coupled with inadequate resources and lack of funding, work against the optimization of a MSW disposal service. In the authors’ view, authorities in charge of waste management need to change not only behaviors, but modernize their processes. Recycling technology is a key part of the solution. A model has been developed which suggest the involvement of stakeholders to achieve meaningful sustainable MSWM. This can be achieved by recognizing the role of the informal sector through community-based organizations, Non-Governmental Organizations (NGOs), and the private sector. The open dump approach is leading to severe environmental consequences as the groundwater and soil within the dump is been contaminated. In this study, an integrated municipal solid waste management approach was developed with a model to help achieve sustainable municipal solid waste management. Resource recovery, not waste disposal, must be the ultimate goal with clearly defined end user markets so that the recovery loop is complete. Mandatory sorting of waste at household level would help greatly in making recycling activity successful.     

Tackling environmental issues in industrial ceramic sintering of sewage sludge: odors and gas emissions

The inertization of sewage sludge in ceramic matrices to be used in structural or red ceramic material for buildings has proved to be a good case of reuse of waste material. However, its practical application has not yet been fully implemented in real-case scenarios, and environmental concern seems to be the main hurdle to overcome for its definitive massive approval by the building industry. In this contribution, air emissions related to the sintering of ceramic bricks made of mixtures of clay with some percentage of sewage sludge have been analyzed (in terms of gases, suspended particles and odors). Tests conducted during this work have shown higher VOC emissions in samples with some percentage of sludge in their composition (still under the regulated emission limit values), and some of them (mercaptans) are associated with odor nuisances. Besides, limit emissions values were exceeded by three inorganic pollutants (suspended particles, NO_x and HCl). Measurements in an industrial scenario test showed a high variability in air pollution emissions, suggesting the need of in situ testing for definitive implementation. With the experience collected in this and several previous works in the area of emissions related to the production of added sewage sludge ceramic, some guidelines and recommendations are given to minimize the environmental impact of ceramic production plants implementing this particular waste revalorization process. Guidelines cover different aspects: workplace implementation of gas cleaning equipment; geographical context and local wind pattern analysis; monitoring of emission and immission levels; and information policy through social control participation procedures for reporting of nuisance episodes.     

Movement of a tritium plume in shallow groundwater at a legacy low-level radioactive waste disposal site in eastern Australia

Between 1960 and 1968 low-level radioactive waste was buried in a series of shallow trenches near the Lucas Heights facility, south of Sydney, Australia. Groundwater monitoring carried out since the mid 1970s indicates that with the exception of tritium, no radioactivity above typical background levels has been detected outside the immediate vicinity of the trenches. The maximum tritium level detected in groundwater was 390 kBq/L and the median value was 5400 Bq/L, decay corrected to the time of disposal. Since 1968, a plume of tritiated water has migrated from the disposal trenches and extends at least 100 m from the source area. Tritium in rainfall is negligible, however leachate from an adjacent landfill represents a significant additional tritium source. Study data indicate variation in concentration levels and plume distribution in response to wet and dry climatic periods and have been used to determine pathways for tritium migration through the subsurface.     

Natural radioactivity and radon exhalation in building materials used in Italian dwellings

Forty-two samples of building materials commonly used in Italian dwellings were surveyed for natural radioactivity. External (gamma), as defined and used by the European Commission, and internal (alpha) hazard indexes were calculated and radon specific exhalation rate and emanation fraction were measured. The accumulation method, by using the E-PERM electret ion chambers, was employed to determine specific exhalation rates of 222Rn. Several of the materials had hazard indexes that exceeded the European Commission limit values. However, it was evident that limit values for internal hazard indexes set based on Rn emanation should take into account the properties and use of the materials. For example, Rn emanation from basalt and glazed tiles was substantially lower than the Rn emanation from other materials with similar hazard indexes. Clearly there is need for improved guidelines and regulations in this area.