The most abundant natural biopolymer on earth,cellulose fiber,may offer a highly efficient,low-cost,and chemical-free option for wastewater treatment.Cellulose is widely distributed in plants and several marine animals.It is a carbohydrate polymer consisting of β-1,4-linked anhydro-D-glucose units with three hydroxyl groups per anhydroglucose unit (AGU).Cellulose-based materials have been used in food,industrial,pharmaceutical,paper,textile production,and in wastewater treatment applications due to their low cost,renewability,biodegradability,and non-toxicity.For water treatment in the oil and gas industry,cellulose-based materials can be used as adsorbents,floc-culants,and oil/water separation membranes.In this review,the uses of cellulose-based materials for wastewater treatment in the oil & gas industry are summarized,and recent research progress in the following aspects are highlighted: crude oil spill cleaning,flocculation of solid suspended matter in drilling or oil recovery in the upstream oil industry,adsorption of heavy metal or chemicals,and separation of oil/water by cellulosic membrane in the downstream water treatment.