Removal of fluoride and total dissolved solids from coalbed methane produced water with a movable ultra-low pressure reverse osmosis system

The aim of this project was to establish an economical and environmentally benign technology for removing fluoride (F-) and total dissolved solids (TDS) from coalbed methane (CBM) produced water. The proposal involved a movable wastewater treatment system comprised of a flocculation sedimentation pretreatment unit and an ultra-low pressure reverse osmosis unit in Liulin County, Shanxi Province, China, where concentration of F- ranged from 1.3 to 18.2 mg/L and concentration of TDS ranged from 2800 to 6,600 mg/L. When the hydraulic load was 2–4 m3/day with the running mode in 10 h cycles at 10–15 days interval, the removal efficiency was 94.7% for F- and 98.1% for TDS with 55% water recovery from June to November 2011. Concentrations of F- and TDS in effluent were lower than the permissible discharge standard values of pollutants for irrigation and livestock. The flexible deployment and small footprint affordable was appropriate for removing pollutants from CBM mining areas with low water production and discommodiously decentralized treatment.