A method and system for purifying production water obtained from oil and gas operations so that the purified water need not be disposed of by forced injection back into the geological formation but can be put to a beneficial use such as agriculture, irrigation, industrial or municipal or potable applications. The production water is treated in a ceramic microfilter after it has been pretreated (preferably by aeration and with a walnut shell filter) to remove volatile hydrocarbons and heavier oils, such as paraffins and asphaltenes, that could foul the ceramic filter. The permeate from the ceramic microfiltration can then be treated with activated charcoal or otherwise treated to meet the specific requirements for the intended beneficial use.