Hypersaline drilling mud water treatment using pretreatment-free DCMD process

Abstract

Membrane distillation (MD) can be applied to treat highly polluted saline wastewaters. This work is an attempt to treat drilling mud water (DMW) directly without any pre-treatment processes. In this regard, commercial polytetrafluoroethylene (PTFE) and nanofibrous styrene-acrylonitrile (SAN) membranes were employed. Nanofibrous SAN membranes were fabricated via the high-throughput electroblowing process. A water contact angle (WCA) of 144.2° was obtained for the hot-pressed SAN membrane, which was higher than that of the PTFE membrane (128.3°). Two treatment cycles were performed for each membrane using direct contact membrane distillation (DCMD) process. In the first cycle, hydrophobic membranes were subjected to the DMW. The removed membranes were washed. Then, for the second cycle, were subjected to the diluted DMW of the first cycle. The distillate water quality showed a declining trend using the PTFE membrane at the end of the second cycle. However, due to higher wetting resistance, distillate water with a better quality and a more stable flux was achieved for the SAN membrane. The DCMD tests were terminated when water recovery reached around 60 %. This work demonstrated that the MD process is a suitable option for treating complex and highly saline wastewaters.