Dec 15, 2014

Equalizing the Flow in Paradise

Equalizing the Flow in Paradise

A remote Caribbean island resort owned by a global corporation faced myriad challenges related to its existing sequencing batch reactor (SBR). It needed a new solution for water treatment that would save money and reduce corporate risk. The wastewater from a temporary destination location can be a challenge to effectively treat due to transient visitors who can swell the resort population from a few to a few thousand in a short period of time. With a combination of quick delivery options, small footprint and the flexibility needed for the influx of visitors each day, Ovivo’s microBLOX was an ideal solution.

The resort’s parameter for flow was little or no flow to a maximum flow of 28,000 gal per day. These flow variations are weekly occurrences, and the system had to adapt to each day’s flow and treat on demand. After a series of evaluations, the microBLOX ready-to-operate process intensified membrane bioreactor (MBR) option supplied the necessary operating parameters, along with customer support and smart systems.

MBR Advantages

MBR technology allows for process intensification, which is the principle behind the design and operation of this facility. Activated sludge processes are intensified as the concentration of active biomass is increased and, proportionally, process volume is decreased. Using membranes instead of sedimentation to remove solids allows for concentrations three to five times higher than conventional technologies. Further intensification, however, primarily is limited by the oxygen uptake rate (OTR) required for the biological process. OTR is a function of oxygen saturation, which is about 10 parts per million at ambient conditions, and diffuser performance. Supersaturating a slip stream with the use of concentrated oxygen overcomes these limitations and can increase treatment capacity by a factor of 25% to 50%, depending on site/process conditions (e.g., food-to-mass ratio). Conventional activated sludge plants run at mixed liquor suspended solids (MLSS) concentrations of about 3,000 mg/L, and conventional MBR plants run at 10,000 mg/L when optimized for energy and given diffuser performance limitations at higher solids concentrations. The preferred range of MLSS concentrations for the high-rate, single-stage system is 20,000 to 30,000 mg/L.

High-rate, single-stage MBR solutions offer the following advantages: 

  • Maximized turndown capabilities, thereby reduced energy typically found during low-flow conditions;
  • Reduced system footprint requirements;
  • Increased plant capacity within the existing infrastructure; and
  • Increased system simplicity and reliability and lower total installed cost.

Installation Challenges 

With the dire condition of its existing system, the resort needed the new treatment plant operating as soon as possible. The MBR system was delivered and operational 12 weeks after the initial order. Even with the challenges of a limited crew on a remote island, the onsite installation was completed in two weeks.

Commissioning was tricky because there was no available seed sludge on the island. Ovivo worked with plant operators to gradually build from zero biology to a well-developed MLSS in four weeks.

The value received by the client goes beyond a single transaction. The client was satisfied with the services in customer support, warranties and smart systems. It found a solution that met its rigorous standards and a smart system to monitor the plant from any location and allow for the operator to watch for any problems that may arise. 

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