CORRECTING THE SOIL pH USING A METALLURGICAL WASTE

Soil acidity is among the important environmental factors which can influence plant growth and can seriously limit crop production. Therefore, liming acid soils is basic to maintain an optimal pH. Soil pH has a large influence on the availability of plants nutrients. The steel slag can be used as an amendment for an acid soil considering the high contents of CaO and MgO. The paper presents the preliminary obtained data regarding the use of steel slag resulted as a metallurgical waste from a Romanian steel refinery and its effect on the soil pH. The physical and chemical characteristics of the acid soil are presented. The effects of the steel slag applied at different rates on soil pH have been investigated in the laboratory experiment

THE INFLUENCE OF AN INDUSTRIAL SLAG ON THE MACROELEMENTS CONTENT IN THE SOIL

To maintain the quality of the soil it is required its use according the characteristics it has. This implies the inclusion on the appropriate use of any kind of waste, nutrients and pesticides management; improve physical and chemical characteristics, to avoid pollution. The ability of steel slag to improve the characteristics of acidic soils may be explained by the high content of calcium and magnesium. The paper describes the changes that occurred with regard to existing macroelements in soil as a result of using different doses of steel slag (0%; 0.1%; 0.2%; 0.3%; 0.4%; 0.5%) for the purpose of amending the soil.Macroelements such as nitrogen, phosphorus and potassium, as well as organic carbon content are presented. Changes in the total nitrogen content and soluble potassium content were strongly influenced as a result of treatment

Bioremediation Potential of Native Hydrocarbons Degrading Bacteria in Crude Oil Polluted Soil

Bioremediation of crude oil contaminated soil is an effective process to clean petroleum pollutants from the environment. Crude oil bioremediation of soils is limited by the bacteria activity in degrading the spills hydrocarbons. Native crude oil degrading bacteria were isolated from different crude oil polluted soils. The isolated bacteria belong to the genera Pseudomonas, Mycobacterium, Arthrobacter and Bacillus. A natural biodegradable product and bacterial inoculum were used for total petroleum hydrocarbon (TPH) removal from an artificial polluted soil. For soil polluted with 5% crude oil, the bacterial top, including those placed in the soil by inoculation was 30 days after impact, respectively 7 days after inoculum application, while in soil polluted with 10% crude oil,  multiplication top of bacteria was observed in the determination made at 45 days after impact and 21 days after inoculum application, showing once again how necessary is for microorganisms habituation and adaptation to environment being a function of pollutant concentration. The microorganisms inoculated showed a slight adaptability in soil polluted with 5% crude oil, but complete inhibition in the first 30 days of experiment at 10% crude oil

THE DIVERSITY OF HETEROTROPHIC BACTERIAL MICROFLORA IN SOIL POLLUTED WITH CRUDE OIL AND DIFFERENT TREATMENTS

Petroleum hydrocarbon pollution is one of the main environmental problems, not only bythe important amounts released but also because of their toxicity. It is known that the mainmicroorganisms consuming petroleum hydrocarbons are bacteria. The present researchwork reports the diversity of microrganis from crude oil polluted soil been treated with anatural biodegradable product and bacterial inoculum. The bacterial inoculum was used toenrich indigenous microbes to enhance biodegradation rate. In soil excessively polluted with crude oil, bacterial population size in conditioned variant with Ecosol maximum dose (1%) presented values comparable to those of inoculated variants, demonstrating the protective and stimulation effect of soil bacteria, including those involved in the degradation of petroleum hydrocarbons exercised by organic compound applied Ecosol

STEEL SLAG-AMENDMENT FOR ACIDIC SOILS

Acidic soils are soils that have a pH less than 6,5. There are several ways to raisethe pH of acidic soils, the addition of amendments is one of them.The steel slag can be an effective liming material in the favorable soil conditions forproductive plant growth; it can be used as acidic soils amendment considering the high contents of Ca and Mg.To find out if the soil needs modification, have it tested and also should take intoaccount the soil test recommendations to apply the steel slag as amendment

Effects of Heavy Metal from Polluted Soils on the Rhizobium Diversity

Heavy metals adversely influence microorganisms, affecting their growth, abundance, genetic diversity, nodulation ability and efficacy. The aim of this study was to isolate and characterize free-leaving Rhizobium from soil which were artificially polluted with Cu (100, 250, and 500 mg kg-1 soil), Zn (300, 700, and 1500 mg kg-1 soil) and Pb (50, 250, and 1000 mg kg-1 soil), but also with a mixture of all these metals, and cultivated with red clover (Trifolium pratense L.), and to compare them with bacteria isolated from similar type of soil, but unpolluted. Rhizobia from soil were isolated on YMA medium with or without bromothymol blue (0.00125%) as a pH-change indicator and the morpho-physiological characteristics of the colonies were examined. The number of Rhizobium was estimated using the most probable number method. Compared to the control, a decrease of rhizobia number and an increase of the metal concentration were observed. Several decameric primers (Operon Technology type) were used and a reduced polymorphism among isolated bacteria was observed. Moreover, significant differences were observed among these strains and the collection strains used as reference. Also, when primers nodCF/nodCI for detection of nod genes were used, several amplicons were obtained, different from the results obtained with similar strains isolated from unpolluted soil. These results suggest that the survival „price†of the Rhizobium in such polluted area was the alteration of some genes, including those involved in symbiosis and, probably, in nitrogen fixation

STEEL SLAG, A SUBSTITUTE OF LIMING MATERIALS IN AGRICULTURE

Regular application of amendments and fertilizers in required doses causes significant and lasting chemical changes in the soil, in relation with the degree of success of crop production. Steel slag is a highly alkaline material considered a by-product of the steelmaking process. This material is used in many different applications including the amendment for acid soils. Amendment is a practice commonly used for rapid elimination of problems of soil acidification. As a product applied in agriculture, the steel slag has been studied in many parts of the world somewhat with satisfactory results. In some European countries, researches have shown an improvement in acid soil properties. The ability of the steel slag to improve the acidity of the soil can be explained by the high content of CaO and MgO and Al2O3 low. When a liming material such as limestone or steel slag is evaluated, it is compare to calcium carbonate, and its neutralizing value is called the Calcium Carbonate Equivalent (CCE) value. Application of amendments, including by-products such as steel slag can restore soil quality by balancing the pH value, organic matter intake, increasing water retention capacity, reducing compaction, etc. For reasons of environmental protection, steel slag properties should always be tested given the wide variety in terms of their physical and chemical indicators

THE INFLUENCE OF DIFFERENT TREATMENTS OF SOIL POLLUTED WITH CRUDE OIL ON PLANT BIOMASS

The aim of this research was to improve the bioremediation technology for soils that are polluted with crude oil through biostimulation, bioaugmentation and phytoremediation. The soil artificial polluted with crude oil have been treated with a natural biodegradable product and bacterial inoculum. The plant used in the greenhouse experiment is maize. In this paper is presented the influence of different treatments on plant biomass. It will be shown the influence of crude oil on plant growth (plant number/pot, plant length, leaves number and plant biomass) in a soil treated with a natural biodegradable product and inoculated with bacterial inoculum. According with the results obtained, this method could be used in field for rehabilitation and reuse in agriculture of polluted soils with crude oil