Novel Sequential Treatment Methodology for Disposal of Water-Based Waste Drilling Mud

Abstract

An integrated technology, consisting of solid–liquid separation, filtrate treatment, and solid mud reusing, is proposed based on a comparative analysis of existing methods. Systematic experiments with actual waste drilling mud were conducted. Initially, solid–liquid separation of the drilling mud was achieved by emulsion breaking with 80% H2SO4. The optimal filtration rate was gained when the operating pH and density were adjusted to 3 and 1.15 g/cm3, respectively. Then, Fenton oxidation was applied to the filtrate; for a maximum CODCr removal efficiency, the pH of the filtrate was found to be about 3–4, whereas the optimal dosage of [H2O2] was 0.55 and 0.0625 M, respectively. After being neutralized with CaO and aerobic digestion with active sludge, the removal efficiency of CODCr in filtrate exceeded 98%, leaving the CODCr less than 100 mg/L. Meanwhile, for solid mud reuse, different formulas were proposed for baking-free bricks. Test results indicated that, at a proper formula, the compressive strength of the brick can reach more than 10 MPa, whereas the CODCr in the leaching liquid can be less than 60 mg/L. The whole technology shows a satisfactory CODCr removal performance and provides a feasible alternative for the disposal of waste drilling mud.