High quality water from refinery waste

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STANIC Industria Petrolifera of Livorno (Italy), is a major Refinery of the AGIP group which has a capacity to process 5,200,000 tons of crude oil per year. STANIC recently decided to study the feasibility of reclaiming the effluent from their biological waste treatment plant which is currently discharged to the sea. The reclaimed water will be used for cooling tower makeup and feed to the boiler demineralization plant. All refinery wastes pass thru an API separator followed by a floatation-flocculation unit. The waste is then treated in an activated sludge biological treatment plant followed by a final aeration prior to discharge. The refinery also has an existing standard clarification gravity filtration plant used to treat municipal water prior to their boiler feed ion exchange system. It is anticipated that this water treatment plant (or portions of it) will be incorporated into a waste water recovery system. Consideration was given to the use of both the reverse osmosis (RO) and the electrodialysis reversal (EDR) membrane processes. However, the demands by refinery operation on the existing water and waste treatment would result in fluctuating quality of the water available to feed the membrane units. It was evident that the reclamation plant would have to withstand short periods (up to several days) when portions of the existing treatment facilities were not available for use. These conditions could result in the possible damage to the membranes by several means:1.1) Oil fouling2.2) Organic fouling3.3) Bacterial attack4.4) Chlorine leakage5.5) Plugging because of high SDI levels6.6) Metallic precipitates. 1) Oil fouling 2) Organic fouling 3) Bacterial attack 4) Chlorine leakage 5) Plugging because of high SDI levels 6) Metallic precipitates. The best chance of successful wastewater reclamation appeared to be with the EDR System which has previously demonstrated its ability to operate under several of the above conditions. However, evidence did not exist of successful EDR operation under the combination of pollutants potentially existing in the Refinery's waste water. The key unanswered question was wether the membranes had the capability of withstanding long term to various pollutants. It was decided that a pilot plant was required prior to committing to a full scale plant. A containerized EDR pilot plant was obtained which included a membrane module using full sized EDR components. The use of a standard sized EDR membrane stack was considered essential to develop reliable data upon which to base a full scale system.