Reprinted from September 2016HYDROCARBON ENGINEERING

T he Petron Bataan Refinery (PBR) is the largest integrated crude oil refinery and petrochemicals complex in the Philippines. The facility is located in Limay, on the southeastern

side of Bataan, a coastal province situated west of Luzon Island. It is bound by the municipalities of Orion in the

north, Mariveles in the south, Bagac in the west and the Manila Bay in the east. Located just 40 km west of Manila, the capital, business hub and main seaport of the Philippines, Limay is an ideal host for facilities of strategic national importance. PBR processes crude oil into a full range of petroleum products at the facility,

Pierre Frédéric Diaz, Veolia Water Technologies, France, and Robert Wenta, Veolia Water Technologies, USA, explain how the implementation of a new

wastewater system helped to improve water quality and lower feedstock costs at the Petron Bataan Refinery in the Philippines.

PERFECTPURITYPERFECTPURITY

Reprinted from September 2016HYDROCARBON ENGINEERING

including gasoline, diesel, liquefied petroleum gas (LPG), jet fuel and kerosene. PBR also produces petrochemical feedstock, benzene, toluene, mixed xylene and propylene.

PBR wanted to expand production to process 180 000 bpd of crude oil, while changing its feedstock from Arab Light to less costly heavy and sour crudes. The process changes required a new wastewater treatment plant to handle the new effluent characteristics that would result from these changes. Daelim Industrial Co. Ltd contracted Veolia to provide the water treatment facilities for the refinery as part of its expansion project, known as RMP-2. Daelim Industrial, with its Engineering & Construction and Petrochemical groups, is a global contractor with leading edge technologies and management abilities.

Veolia Water Technologies developed a compact process to meet the needs of the Bataan refinery, while minimising the cost without affecting the performance of the plant and complying with the stringent water quality standards for discharge into Manila Bay. In this compact plant, Veolia’s proprietary technologies included Tilted Plate Interceptors for free oil separation, an AnoxKaldnesTM biological activated sludge (BAS) system and HydrotechTM disc filters for final treatment before discharge. The gravity flow design of the 700 m3/hr system will ensure availability and save energy throughout the life of the plant.

The processThe wastewater treatment plant consists of primary, secondary and tertiary treatments: the primary treatment is to adjust pH and remove oil/suspended solids contents. The secondary treatment removes pollutants using the AnoxKaldnes BAS system. Tertiary treatment consists of the Hydrotech discfilters and UV disinfection systems. The treated effluent is routed directly to Manila Bay.

Excess bio-sludge and oily sludge cakes generated from the wastewater treatment plant are disposed in a

Figure 1. The BioDAFs and the disc filters (top centre).

Figure 2. The coagulation/flocculation tanks, pretreatment dissolved air flotation (DAF) unit, and MBBR/BAS systems during the construction phase.

Figure 3. In the BAS process, the high rate MBBR evens the load and acts as a guard to the more sensitive activated sludge process, resulting in a much smaller footprint for the overall system.

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landfill after further treatment by a third party contractor. All gaseous wastes (overhead of oily systems) are treated in a volatile organic compound (VOC) system that treats 5000 Nm3/hr, and a deodourisation package is provided to treat potential odours from the sludge treatment processes.

The plant also provides a number of additional benefits for the refinery, including:

n The Veolia design enables waste oil recovery at a high quality, with more than 70% oil content in the recovered oil.

n All primary treatment equipment is fully covered, prohibiting any VOC emissions into the atmosphere, and thus increasing operator safety at the plant.

n The treated water meets stringent international standards for discharge into the environment. Chemical oxygen demand (COD) is consistently reduced from 4600 ppm to <60 ppm, oil from 1300 ppm to <0.5 ppm, and phenol from 190 ppm to <0.05 ppm.

The technology

Biological wastewater treatment The BAS biological wastewater treatment process is the optimally designed combination of the moving bed biofilm reactor (MBBR) and activated sludge processes. In this configuration, the stable and robust MBBR handles large variations in load, and acts as a guard for the more sensitive activated sludge system.

In the MBBR, microorganisms grow on the surfaces of plastic carriers that are kept in suspension by aeration. The movement of the carriers through the water confines the biological growth to the protected surface area, sloughing off any excess for removal in subsequent treatment steps. The continuous motion of the carriers promotes exchanges between the wastewater and the biofilm, allowing pollutants to be degraded and effluent requirements to be achieved.

The loading capacity of the BAS treatment process is 2 - 3 times higher than a conventional activated sludge system, due to the dramatically reduced load on the activated sludge by the preceding MBBR. The result is a much smaller footprint.

Veolia’s AnoxKaldnes MBBR technology is installed in approximately 600 applications worldwide. In addition to refinery and petrochemical applications in the oil and gas industry, it is also used to treat fracturing flowback and produced water to reduce organics in the water from exploration and production operations.

MBBR technology was invented by Hallvard Ødegaard in the mid-1980s in conjunction with a small Norwegian company, Kaldnes Miljøteknologi (KMT), with funding from the Norwegian government. The first MBBR was installed in Steinsholt, a small village in Norway, in 1989. KMT merged with the Anox company of Sweden to form

Figure 4. The plastic media provides a highly protected surface area to promote the growth of the microorganisms that treat the wastewater.

Figure 5. Based on the process needs, the optimal filter pore size, package option and number of units will be recommended as part of a full scale system design. Pilot testing units can be used to validate system performance prior to full scale installation.

Figure 6. Filter panels can be easily removed by opening two fasteners, without the need to drain the tank.

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AnoxKaldnes, which was purchased by Veolia in 2007. As the history of this technology dates back to the original inventor, Veolia’s AnoxKaldnes team has a wealth of project experience. Ongoing research and development ensures that AnoxKaldnes remains on the cutting edge of new technological innovations.

Disc filter technologyAs in the Petron Bataan wastewater treatment system, Hydrotech disc filter technology is often installed as a tertiary treatment step following an MBBR process to provide an absolute barrier to any particulates that might carry over from the biological processes and the BioDAF. The woven media is stretched onto panels that are installed as a series of discs within the filter housing. Pore sizes of the filter media range from 10 - 1000 microns.

The water to be treated flows by gravity into the filter segment from the centre drum. Solids accumulate on the inside of the filter panels mounted on the two sides of the disc segments. As the solids accumulate, the flow of water through the disc is impeded and the water level inside of the discs begins to rise. The higher water level triggers drum rotation to provide clean panels for filtration and the start of a backwash cycle to clean the fouled panels.

A high pressure rinse removes the accumulated solids from the filter media and into the solids collection

trough. Solids are intermittently pumped from the bottom of the trough.

Disc filters can be provided in either tank or frame units for placement in civil structures. Flow capacity of the disc filters range from 10 000 gal./min. for a tank unit, or 14 200 gal./min. for a frame unit. Multiple units are installed to handle high flow rates.

Operators believe that the beauty of the disc filter lies in its simple maintenance. No tools are required for inspection or replacement of the backwash nozzles, and there is no need to drain the tank prior to inspection and maintenance. In addition, only two fasteners have to be removed to release each filter panel in the event that replacement is required.

In the oil and gas industry, disc filters have been installed at refineries and petrochemical plants to remove solids from supply water for various processes, and as a final treatment step prior to the discharge of wastewater.

ConclusionVeolia provided Petron with a plant that fully meets stringent international standards of the water treatment industry. It is a user friendly and easy to operate plant with reliable performance and multiple mitigation paths to accommodate influent variation and off-specification refinery production.