Feasibility of vermicomposting for spent drilling fluid from a nature-gas industry employing earthworms Eisenia fetida

• Main Authors: Zhe Wang, Zhikun Chen, Yuhua Niu, Peng Ren, Mingde Hao
• Format: Article
• Language: English
• Published: Elsevier 2021-05-01
• Series: Ecotoxicology and Environmental Safety
• Subjects: Vermicompost; Spent drilling fluid; Reproduction rate; Nutrient transformation; Seed germination; Chromosomal abnormality
• Online Access: http://www.sciencedirect.com/science/article/pii/S0147651321001056

This study investigated the vermicomposting of spent drilling fluid (SDF) from the nature-gas industry mixed with cow dung in 0% (T1), 20% (T2), 30% (T3), 40% (T4), 50% (T5), and 60% (T6) ratio employing Eisenia fetida under a 6 weeks trial. Eisenia. fetida showed better growth and reproduction performances in the first three vermireactors (T1–T3), and the mortality was higher in the vermireactors that contained more spent drilling fluid (≥40%). Vermicomposting results in a decrease in total organic carbon, C/N ratio, and an increase in EC, total nitrogen, total phosphorous, total potassium compared to their initial values. The RadViz and VizRank showed that vermicomposting results in a greater impact on the C/N ratio (15.24–35.48%) and EC (7.29–26.45%) compared to other parameters. Activities of urease and alkaline phosphatase during vermicomposting initially increased and then declined suggesting vermicompost maturity. Also, seed germination, mitotic index and chromosomal abnormality assays using cowpea signified that the vermicomposts T2 is suitable for agricultural use due to the lower phytotoxicity and cytotoxicity. The results indicated that SDF could be converted into good quality manure by vermicomposting if mixed up to 20% with cow dung.