【正文】 fullscale facility for the treatment of produced water . Product water from this treatment was reported to be free of suspended solids and nearly all nondissolved anic carbon . Ceramic UF/MF membranes can operate in both crossflow filtration and deadend filtration modes and have a lifespan of 10 years. Chemicals are not required for this process except during periodic cleaning of membranes and precoagulation (used to enhance contaminants removal). Reverse osmosis and nanofiltration RO and NF are pressuredriven membrane processes. Osmotic pressure of the feed solution is suppressed by applying hydraulic pressure which forces permeate (clean water) to diffuse through a dense, nonporous membrane . Seawater RO can remove contaminants as small as 181。 Produced water treatment technologies Ebenezer T. Igunnu and Gee Z. Chen* + Author Affiliations Faculty of Engineering, Department of Chemical and Environmental Engineering, and Energy and Sustainability Research Division, University of Nottingham, Nottingham NG7 2RD, UK Abstract： Produced water is a plex mixture of anic and inanic pounds and the largest volume of byproduct generated during oil and gas recovery operations. The potential of oilfield produced water to be a source of fresh water for waterstressed oilproducing countries and the increasing environmental concerns in addition to stringent legislations on produced water discharge into the environment have made produced water management a significant part of the oil and gas business. This article reviews current technologies for the management of produced water, examines how electrochemical techniques may be used in these areas and pares the prospects for future development. It suggests that treatment technologies based on electrochemistry could be the future of produced water management, since produced water is a potential electrolyte because it has a relatively good conductivity. It also explains that by applying photoelectrochemistry, water electrolysis, fuel cell and electrodeposition, electrochemical engineering could achieve energy storage, production of clean water and recovery of valuable metals from produced water with minimal or no negative impact on the environment. Key words ： produced watertreatment technology electrochemistry electrodeposition photoelectrochemistry 1 INTRODUCTION Petroleum is a major source of energy and revenue for many countries today, and its production has been described as one of the most important industrial activities in the twentyfirst century. Since late 1850s when Edwin Drake drilled the first oil well, demand for petroleum has continued to rise. It is estimated that world daily petroleum consumption would increase from 85 million barrels in 2021 to million barrels by 2030. Despite its significance, petroleum is produced with large volumes of waste, with wastewater accounting for more than 80% of liquid waste and as high as 95% in ageing oilfields. Generally, the oil/water volume ratio is 1:3. Produced water has a plex position, but its constituents can be broadly classified into anic and inanic pounds , including dissolved and dispersed oils, grease, heavy metals, radionuclides, treating chemicals, formation solids, salts, dissolved gases, scale products, waxes, microanisms and dissolved oxygen . Globally, ～250 million barrels of water are produced daily from both oil and gas fields, and more than 40% of this is discharged into the environment. Currently, oil and gas operators treat produced water via one or more of the following options: ?Avoid production of water: water fractures are blocked by polymer gel or downhole water separators, but this option is not always possible. ?Inject into formations: produced water may be injected back to its formation or into other formations. This option often requires transportation of water, and treatment to reduce fouling and bacterial growth. In the long term, the stored produced water may pollute the underground waters. ?Discharge to the environment: produced water may be discharged to the environment as long as it meets onshore and offshore discharge regulations. ?Reuse in petroleum industry operations: minimally treated produced water may be used for drilling and workover operations within the petroleum industry. ?Apply in beneficial uses: produced water may be consumed for irrigation, wildlife consumption and habitat, industrial water and even drinking water. However, beneficial uses of produced water may involve significant treatment . Environmental concerns and the prospect of beneficial uses have driven research into the treatment of produced water. Current conventional treatment technologies are targeted at removal of heavy metals, oil and grease, suspended solids and desalination, which often lead to the generation of large volumes of secondary waste. For instance, heavy metals are removed as sludge using current treatment technologies . This article reviews current produced water treatment technologies and examines the ability of electrochemically driven technology to store energy, produce clean water and recover valuable materials from produced water with minimal negative impact on the environment 2 PRODUCED WATER MANAGEMENT TECHNOLOGIES The general objectives for operators treating produced water are: deoiling (removal of dispersed oil and grease), desalination, removal of suspended particles and sand, removal of soluble anics, removal of dissolved gases, removal of naturally occurring radioactive materials (NORM), disinfection and softening (to remove excess water hardness). To meet up with these objectives, operators have applied many standalone and bined physical, biological and chemical treatment processes for produced water management. Membrane filtration technology Membranes are microp