Environmental accidents caused by economic activities in the petroleum and gas industry are particularly damaging for the environment, affecting all environmental factors – water, soil, air, biodiversity, human settlements. All economic operators causing a pollution have to support the costs corresponding to assessing the damage caused and to its remediation and this is why it is important to be able to apply the most efficient remediation method. The current paper presents the main methods that can be applied in order to repair the damage caused by an accidental pollution of the soil with hydrocarbons and uses the case study of a polluted area in Dambovita county, Romania, to present the application of the remediation method. The paper presents both the results of investigations carried out on the affected area, the objectives of the remediation process as well as the steps and the time frame required for the remediation process. The severity of the initial pollution in the analysed area makes this a model study whose elements can be used also in other similar situations.

Environmental accidents are inherent to any economic activity. They can affect and even significantly harm all environmental factors. According to the polluter pays principle, economic operators causing a pollution have to support the costs corresponding to the damage caused and to its remediation. A first necessary step in assessing these costs is the investigation of the soil’s contamination. The current paper discusses the main methods used in the speciality practice to assess the extent of the pollution of an area with hydrocarbons and presents the case study of a polluted area in the Dambovita county, Romania. The investigations carried out in this case included both in-situ analyses such as the realizing of pedological profiles on the geometric horizons to the depths to which the pollutant was presumed to have penetrated and laboratory analyses. For example, in the case study, for the soil the laboratory analyses comprised the total contents of petroleum hydrocarbons (determined by IR spectrometry), the moisture (determined by means of the gravimetric method), the pH, the amount of humus (determined by moist oxidation and titrimetry), the total nitrogen content (determined with the Kjeldahl method), mobile phosphorus and potassium (determined with the Engner-Riehm-Domingo method). Precise results obtained through these investigations allow a more efficient response to the environmental damage and a shorter time necessary for the application of remediation measures such as bioremediation.

A series of natural zeolites with different compositions were modified by NH4NO3), alkali treatment (NaOH) and addition of aluminum (Al2(SO4)3). The natural and modified samples were characterized by XRF, XRD, N2 sorption, FTIR, NH3-TPD, SEM-EDS and TGA. The adsorption capacity of natural and modified zeolites was determined for manganese removal. Ion-exchange with NH4+ of NZ leads to the exchange of the Na+ and Ca2 + cations and the partial exchange of the Fe3+ and Mg2 + cations. However, the treatment of the NZ with NaOH and addition of aluminum into the zeolites lead to insignificant change of almost all cations irrespective of composition of natural zeolites. While the treatment of the NZ with NaOH causes significant dealumination and desilication of zeolites, introduction of aluminum increases their aluminum content. FTIR and TGA results showed that decationization, dealumination and desilication give rise to a decrease in hydrophilic nature of NZ. However, manganese adsorption of samples enhances their hydrophilic nature. Surface area and pore volume of zeolites increase with ion exchange and aluminum introduction and decrease with alkali treatment with NaOH. In addition, the treatment with NaOH gives rise to partial collapse of structure with significant desilication and dealumination depending on the concentration of NaOH and composition of zeolite. Ion exchange and aluminum introduction increase surface area and pore volume of samples as well as surface acidity, whereas alkali treatment with NaOH decreases them due to partial collapse of structure with significant desilication and dealumination. The NH3-TPD results showed that treatments alter the acidity of zeolite. While alkali treatment and addition of aluminum decreases the number of weak and medium Brønsted/Lewis acid sites, the number of strong acid sites increases through the introduction of Na+, the removal of silica and the formation of extra framework aluminum species. All modifications, ion exchange, alkali treatment, and aluminum introduction increases significantly the manganese adsorption capacity of natural zeolites depending on composition of zeolites. The pseudo-second-order kinetic model for the adsorption of manganese on all natural and modified zeolites fits well.

The decrease of pollution coming from wastewater resulted from biodiesel production was achieved by the partial catalytic oxidation of the main pollutant, glycerol, to readily biodegradable oxygenated compounds. The catalysts were fine particles of manganese and iron oxides obtained by specific processes. The experimental set-up was performed at temperatures ranging from 80 to 900C and a reaction time of 2 to 6 hours. The pollution was measured by CBO5, its decrease being from 315 mg/L to 61 mg/L.

Remediation and management of contaminated land by what we call historic pollution, i.e. legacies from the past, involves the risk assessment stage. The risk assessment for the presented case was the study of the area's history, the determination of the pollution level on the site, sampling, measurement and quantification of the significance of the pollution (environmental impact). The assessment of soil contamination exposed to crude oil and petroleum products is conducted by comparison between measured concentrations of total petroleum hydrocarbons (TPH) and intervention values (IV). Because TPH concentrations from C10 to C40 do take into considerations specific physic-chemical and toxical properties of the individual compounds our study considers not only TPH assessment, but also PAH and BTEX components. Investigation of historical dumps of petroleum residues, a less sensitive land, was achieved by monitoring TPH and groundwater HAP for ground and groundwater through judicious monitoring drills. Methodology of this study is adopted according to authors experience, following three stages: collection of data, comparison of TPH, PAH and BTEX concentrations versus IV, and establishing of interactions among the petroleum contaminants. The analyzes performed showed that the values determined for the TPH level, for the analyzed soil samples, taken up to the 5 m depth, exceeded the alert threshold (1000 mg / kg dry mater) and even the intervention threshold (2000 mg / kg d.m.) for less sensitive land. BTEX indices record values below the quantification limits. The total HAP content (naphthalene, phenanthrene, anthracene, fluoranthene, pyrene, benzo (a) pyrene, indene (1, 2, 3, cd) pyrene) is well below the alert threshold (25 mg / kg d.m.).

Sol–gel preparation of heterogeneous solid catalysts has been reported by many research groups since the 1980s due to unique advantages such as the possibility of obtaining metastable materials, achieving superior purity and compositional homogeneity of the products at moderate temperatures with simple laboratory equipment. Therefore, ZnO nanocrystals with various shapes were synthesized via sol–gel reactions of zinc acetate dihydrate, ethylene glycol, n-propyl alcohol, and glycerol and calcined at 350 oC(ZnO-350) and 900 oC(ZnO-900). Stability of ZnO in the presence of supercritical water (SCW) was determined by various methods such as FTIR, XRD, TEM, SEM, BET, TPO, H2-TPR and zeta potential. The XRD results showed that ZnO samples calcined at 350 oC and 900 oC have a hexagonal crystal structure. After used in SCW, their XRD phase compositions were unchanged and the hexagonal phase composition was maintained. However, SEM images showed that the particle size of the ZnO samples exposed to SCW increased and partial agglomeration occurred. In addition, the surface area of ZnO samples exposed to SCW decreased due to agglomeration.. According to TGA results, ZnO calcined at 900 ° C showed high thermal stability. When ZnO samples were tested in the gasification of formaldehyde in SCW, the presence of both ZnO in the reaction medium decreased the percent distribution of CH4, CO2 and CO and increased H2 formation. The highest hydrogen formation and highest formaldehyde conversion is found on ZnO calcined at 900 oC.

The objective of the study was the waste characterization for a spent absorbent used for hydrogen sulfide removal from natural gas in a gas production facility. The gas from the wells is previously treated for the removal of heavy fractions hydrocarbons, like C1 – C9. The iron oxides from the adsorbent react with H2S retaining it as iron sulphides. Both products, iron oxides and iron sulphides, are substances with low solubility in water. The waste sample present a significant concentration of nickel and contain iron oxides compounds, which can produce self-heating up to ignition phenomena. Self-heating phenomena was noticed for this waste starting discharging from the desulphurization vessel. The waste was tested with flame in order to identify the potential flammability and the result was positive, most likely due to the traces of gasoline. As a conclusion of the study, this waste was defined as hazardous waste and the proposed codes are 060602* Waste containing hazardous sulphides and 060315* Metallic oxides containing heavy metals.

Now, we are living in a world with a high level of economical development which asks higher quantities of raw materials with lower costs of production. This option is quite impossible to be reached if the source of raw materials will not be changed with a new concept: raw materials from waste. This is the case of polyethylene terephthalate (PET) which is obtained by the reaction of terephthalic acid and ethylene glycol, both compounds being derived from crude oil. A way to obtain PET for new applications is to recycle old PET by different chemical processes, as glycolysis and hydrolysis. This paper presents a comparative study of waste PET processing using glycolysis and hydrolysis as possible methods of chemical recycling. Both processes are carrying out in batch reactors, at almost the same temperature and using the same catalyst - Zn(CH3COO)2 . The differences are the solvent (glycol and water) and the pressure inside of the reactor which is 40 bar for hydrolysis and 1,2 bar for glycolysis. After a time of reaction of 2 hours the main product obtained in glycolysis process is bishydroxy-ethylene-terephthalate (BHET) and terephthalic acid for hydrolysis process. An economical evaluation regarding energy consumption, costs of chemicals and yield of final product could be very useful for the investors interested to develop an industrial process for chemical recycling process of waste PET.