Napier-Reid provided the BIO-BATCH™ Sequencing Batch Reactor Process for the Bagbag Sewage Treatment Plant to treat wastewater with a daily flow of 10,400 m3 per day. The STP will provide sewerage services for 80,000 people and help clear the San Juan River Basin, which empties into Pasig River and Manila Bay.
The facility uses a BIO-BATCH™ Sequencing Batch Reactor (SBR) technology to ensure that the discharged wastewater passes high-quality treatment and adheres to the environmental standards set by the Department of Environment and Natural Resources. The SBR technology also allows Maynilad to build an STP in small land areas that are densely populated.
The Treatment Process
Raw wastewater is delivered by an inflow pipe to two SBR tanks, where it is aerated using membrane fine bubble diffusers to assure proper oxygen supply for removal of BOD and completion of nitrification. Fine bubble diffusers provide low power requirements for the aeration systems. Each SBR train has one air control valve, which switches the blower from one tank to another, and one DO analyzer for each tank to provide real time dissolved oxygen monitoring and control. During the react period, air-off sub-sequences are incorporated to provide anoxic conditions within the SBR tank. Mixers will be in operation during this period. The duration of air-off sub-sequences can be adjusted between 0 to 30 minutes.
In the settle phase, the quiescent conditions are provided for the sludge to settle to the bottom of the tank. The clear water is taken out of the basin under laminar flow conditions by a motor driven decanter without disturbing the settled sludge layer. The decanter travel time from the rest position to the Bottom Water Level (BWL) is preset to maintain constant flow. Excessive amount of sludge is removed by a submersible pump directly after the settle sequence. Part of phosphorus is removed during biological treatment; while some is further reduced by chemical addition through alum feed system.
The cycles and sequences are automatically controlled by process control center (PLC).
Scope of Supply:
- Two SBR trains consisting of:
- Fine Bubble Aeration System and control valves (Design)
- Blower assemblies and DO analyzer (Design)
- Waste sludge pumps (Design)
- Decanter assembly Model SD-11500
- Submersible mixers (Design)
- Alum Feed System (Design)
- Local Control Station in NEMA-4X enclosure
2. One NEMA-12 PLC Control Panel, 230/1/60, providing monitoring and controls for the SBR system
Tatalon Wastewater Treatment Plant, Philippines
The plant processes 8,100 m3 of domestic sewage daily. Napier-Reid’s scope of supply was identical to the Bagbag sewage treatment plant.