Ecological assessment of drilling sludge and development of a method for their bioremediation in Western Siberia

The article considers the issue of bioremediation of drilling sludge. The aim of the research is studying of the microbiological processes occurring in soils based on drilling sludge, with their subsequent application for the biological stage of reclamation of disturbed lands. Microbiological characteristics of drilling sludge and four samples of soils based on it with the addition of diatomite, dolomite flour, peat, gypsum, glauconite, humic preparation “Rostock” in different proportions were studied. Crops were shown on agarized medium: meat-peptone agar (MPA), starch-ammonia agar (SAA), Munz medium, Chapek medium, depending on the determined group of microorganisms. The total number of microflora, the number of saprophytes, microorganisms growing on starch-ammonia agar (SAA), hydrocarbon-oxidizing bacteria (PSB), micromycetes and actinomycetes were estimated. The mineralization coefficient is calculated. The total number of microflora in the samples ranged from 51 to 271 million CFU/g. The share of saprophytes was 16.7-24.8% of the total amount of microflora. The proportion of microorganisms growing on SAA was 15.6-36.6%. The minimum number of PSB was 2.0 million CFU/g of soil; the maximum was 22.0 million CFU/g. The mineralization coefficient varies from 0.81 to 1.63, which indicates different rates of mineralization processes. The number of micromycetes determined on the Chapek medium ranged from 0.01 to 3.33 million CFU/g, on SAA - from 0.03 to 10.4 million CFU/g. At the same time, the number of micromycetes is much lower than the number of bacteria, which is normal for soils. The number of actinomycetes varied from 0.2 to 7.3 million CFU/g. The largest number of actinomycetes was noted when peat and humic preparation “Rostock” were introduced. The share of actinomycetes in the total number of microflora on the SAA ranged from 0.6 to 14%. There is a development of the total number of microflora, an increase in the diversity of microbocenosis, which indicates a decrease in the concentrations of water-soluble salts, petroleum products and the presence of an additional food source in the form of peat. Based on the data obtained, a conclusion was made about the possibility of using soils based on drilling sludge with the addition of peat and humic preparation “Rostock” for the reclamation of disturbed lands.