THE NEXT STEP:
UPGRADE OF THE
AT NORTH HEAD
RECYCLED WATER PLANT
After nine years of operation, SWC considered options to
cater for the increased demand for recycled water at North
K Chow, D Connaire, G James, P Zauner
Publication Date (Web): 5 April 2017
The Recycled Water Plant (RWP) at Sydney Water Corporation's (SWC) North Head Wastewater Treatment Plant (WWTP) was commissioned in August 2005. The RWP consists of a Membrane Bioreactor (MBR) and chlorine disinfection to provide high-quality process water for several processes at the WWTP. The reduction in potable water usage is an integral part of Sydney Water operations with the recycled water being used in several processes at the STP Membrane bioreactor (MBR) suppliers offer lifetime guarantees in the order of 3 – 10 years. Estimates for expected membrane life have been based on loss of mechanical stability, decline in hydraulic permeability and analysis of sales data for new versus replacement membranes. The consensus is that MBR operators should expect a lifetime of 8 to 10 years.
In 2013 Sydney Water conducted a review of potential recycled water needs and determined that the current output from the RWP needed to be increased. Sydney Water asked Evoqua Water Technologies to conduct a detailed audit of the MBR. Based on the options report SWC elected to upgrade the plant.
The upgrade of the North Head RWP provided a unique opportunity to examine long term performance of an MBR installed in Australia as well as to identify the advances in membrane systems.
After nine years of operation, SWC considered options to cater for the increased demand for recycled water at North Head WWTP. An audit performed by the supplier of the original membrane equipment informed SWC's choice of upgrade option. The selected option included the replacement and upgrade of MEMCOR® membrane modules with a new generation product by the original supplier. The upgrade that was done 'on line' while the plant was producing recycled water, resulted in a plant that now produces more recycled water without compromising filtrate quality at lower dollar per ML energy costs compared with the original design. Examining pre and post upgrade plant operating data allowed findings to be made on the performance of nine year old membranes compared with new membranes. The upgrade was also an opportunity to upgrade controls incorporating operating experience from previous years.
The scope required to examine the operation of the RWP through its first 9 years and to consider the changes in membrane technology that have continued to make MBR an attractive technology for the conservation of water resources. Data presented covered plant operation, operational costs and a comparison of the pathogen and virus removal of the RWP from two separate studies.
The existing membrane modules were installed for 9 years:
Study conducted about operation of the existing system and the impacts on performance; and
- Review conducted on filtrate quality
An upgrade with Memcor® B40N membrane modules and a MemPulse™ aeration system followed the study and review:
- Upgrade was all within the existing tankage with the RWP online.
- Upgrade allowed the plant capacity to be increased up to 3.0 ML/d average flow from the current rated average flow of 2.0 ML/d,
- Use of large bubble slug flow of the MemPulse system meant that the scour air blowers did not have to be increased in capacity.
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