BP Service Station, Silverdale, Auckland
Project Description: New Waste Water Treatment Plant
In association with URS Consulting Engineers, Reaman Industries Limited secured a contract to design, supply and install a Waste Water Treatment Plant for BP Oil New Zealand Limited.
Located just north of Albany, Auckland, the plant was required to process all the waste water generated from the motorway service station. High effluent quality was also imperative for the required Resource Consent.
After reviewing all available options, Reaman Industries designed and supplied a cutting edge system called the SEBAS® Sequencing Batch Reactor (SBR). The SBR process enables the optional removal of nutrients (nitrogen/phosphorus) simply by incorporating anoxic/anaerobic mixing during FILL and cycling (on/off) of aeration blowers during FILL and REACT phases.
The essential features of the SEBAS® SBR are the plug-flow initial reaction conditions and complete-mix reactor basin. Each SEBAS® reactor basin is divided by baffle walls into three sections (Zone 1: Selector, Zone 2: Secondary Aeration Aeration, Zone 3: Main Aeration). Sludge biomass is continuously recycled from Zone 3 to the Zone 1 selector to remove the readily degradable soluble substrate and favour the growth of the floc-forming microorganisms. System design is such that the sludge return rate causes an approximate daily cycling of biomass in the main aeration zone through the selector zon. The mechanisms of Zone 1 and the internal sludge recycle eliminate the requirement for separate fill-ratio selectivity, anoxic, and anaerobic mixing periods.
The selector is self-regulating for any load condition and operates under anoxic conditions during aerobic periods and anaerobic reaction conditions during non-aerated periods. Polishing denitrification and enzymatic transfer of available substrate during enhanced biological phosphorus removal is also achieved in the selector zone. The complete-mix nature of the main reactor provides flow and load balancing and a tolerance to shock of toxic loadings, and the process prevents solids washout during peak or wet weather hydraulic surges.
Effectively, the SEBAS® SBR enables the BP Dairy Flat plant to process high strength waste at 60m³/day and still produce high effluent quality. At present 80% of Nitrogen is removed from the effluent.
Part of the overall design by Reaman Industries called for easy maintenance and plant operation. This has been achieved by making the plant operation and control automated. Separate flow and load balancing are not required ensuring that the process is not fixed in the physical design of the plant.
Contract Value: $890,000
Construction Period: 8 Months