(146a) Desalination and Water Reuse Technologies in the Petroleum Refining Industry

Water is essential to many petroleum refinery operations. In fact, a typical refinery handles more water than oil for a variety of heating, cooling and process operations. As fresh water resources face growing pressures, alternative supply sources have to be considered and new, more effective treatment technologies must be employed to meet increasingly strict quality limitations placed on industrial wastewater discharges. Fortunately, advances in treatment technologies ? particularly membrane and desalination technologies ? are providing new treatment options.

Maturation of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) have proven effective at reducing water treatment costs while simultaneously improving treated water quality. The application of an appropriate membrane process often makes it practical to treat marginal and brackish water sources that would not otherwise have been considered. Even seawater desalination is proving a viable option at many refineries around the world.

Membrane technologies have also increased wastewater treatment options. The membrane bioreactor (MBR) process ? which combines an aerobic biological process with an integrated, low-pressure membrane system ? is an accepted wastewater treatment technology that is now being considered for many new wastewater treatment plants and plant upgrades. MBRs produce a higher quality effluent, reduce plant footprints, and provide effective pretreatment if a subsequent RO process is to be considered.

These new technologies have led to a dramatic increase in the use of reclaimed wastewaters within petroleum refineries. Dual membrane systems integrating low-pressure MF/UF with RO may be used to repurify secondary or tertiary effluents to virtually any desired level of quality; water suitable for boiler make-up and/or a variety of process water applications. In addition to treating their own internally produced wastewaters, many refineries are turning to repurified municipal wastewater as a ?new' water source.

Membrane processes may be combined with thermal treatment systems to achieve zero or near zero liquid discharge. These hybrid arrangements often result in reduced energy consumption and in some cases, are able to recover waste heat as an energy source.

An increasing number industrial water supply projects now consider desalination and water reuse as economically competitive, drought-proof water management options. This presentation will review the membrane and evaporative technologies that are making this possible, and will consider how they may be being applied within a petroleum refinery.

The information will be supported by the presentation of case histories and operational data from refineries in the USA, Australia, the Caribbean, India, and Saudi Arabia.