Effect Of Waste Drilling Mud By Inoculating Effective Degrading Bacteria In Mud-soil Mixture System

In this paper, we carried out one small-scale field experiment to determine the degrading effect of waste drilling mud by inoculation of effective degrading bacteria. The dynamics of soil microorganisms in different treatments, variation of pollution matter concentration in mud-soil mixture system and the soil nutrient content was determined at different time. The results were as follow:(1) The number of cultured bacteria, fungi and actinomycetes appeared the regular variation, i.e. decreasing-increasing-decreasing, and increasing finally, both in the mud-soil mixture system and the control soil during the detection time on the 0th d, 30th d,90th d,180th d,270th d and 360th d. The number of bacteria and actinomycetes in mud-soil mixture system was significantly higher than that of the control all the time.(2)Both soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) showed the same regular variation as that of microbial number in the mud-soil mixture system and the control soil. SMBC and SMBN of the mud-soil mixture system was 2.9-3.5 times and 1.9-3.2 times higher than that of the control.(3) Correlation analysis showed that there was positive significance correlation (p<5%) between SMBC, SMBN and the bacterial number, and also the positive significance correlation was exited between SMBC, SMBN and the number of actinomycetes (p<1%).(4) PCR-DGGE analysis of soil uncultured bacteria showed that the diversity of bacterial populations in the mud-soil mixture system was higher than that in control soil, and the bacterial population was fluctuating in the mud-soil mixture system, but was stable in control soil on the 0th d,30th d,90th d,180th d,270th d and the 360th d.(5)From the 0th d to the 360th d, the content of soil elution liquid color, COD, concentration of Cl-, SO42- and oil content of soil elution liquid in the mud-soil mixture system decreased gradually, and the removal rate reached to 48.6%,63.8%, 80.5%,61.0%and 74.3%, respectively, which showed there was a good degradation effect. The content of Cd was according with the national secondary standard of environmental quality for soil, the content of Pb, Cu, Zn, Cr was according with the national primary standard. Compared with the control soil, the content of heavy metals (Cd,Zn,Cr) in Clover,Ryegrass,Bamboo and Alder leaves planting in the mud-soil mixture system had not significant difference, however, the content of Pb and Cu changed significantly.(6) On the 0th d,30th d,90th d,180th d,270th d and 360th d, the content of total nitrogen, organic matter, available potassium and available nitrogen in the mud-soil mixture system was significantly higher than that in the control soil. Soil fertility condition of the mud-soil mixture system was more suitable for plant growth.