Biofilm Annular Reactor
Variable Shear Biofilm Reactor for Water Distribution and Process Piping Research
The Biofilm Annular Reactor (BAR) grows biofilm under controlled, variable shear conditions that simulate the hydraulic environment of water distribution systems and fluid piping. By adjusting the rotational speed of the inner cylinder from 30 to 500 RPM, researchers can dial in the specific shear stress relevant to the system being studied, independent of fluid residence time. This decoupling of shear rate from flow rate is what distinguishes the BAR from simpler flow-through reactor designs.
Like the Bio-inLine® Biofilm Reactor, the BAR can be used to monitor biofilm development within an actual operating system, providing direct insight into what is forming on pipe surfaces under real flow conditions. Twenty removable slide coupons are flush-mounted on the rotating inner cylinder and can be sampled intermittently without disrupting the experiment. Slides are available in 15 standard materials, allowing researchers to match the coupon substrate to the pipe or vessel material in the system under study.
Reactor Design
The BAR consists of two concentric cylinders. The outer cylinder is stationary and contains the process fluid. The inner cylinder rotates at a speed controlled by a variable-speed DC motor (100 to 240 VAC), generating wall shear stress on the coupon surfaces that can be adjusted to match the conditions found in the piping system being studied. Biofilm accumulates on the 20 slide coupons mounted flush on the inner cylinder surface. The jacketed version (BAR 1420 LJ) adds temperature control capability for studies requiring precise thermal conditions.
BAR 1420 LS
The standard Laboratory Biofilm Annular Reactor. Includes the motor and controller box, glass outer cylinder, rotating inner cylinder with 20 coupon slide slots, and all associated hardware. Suitable for most water and process fluid biofilm applications.
Research Capabilities
The BAR enables kinetic analysis of biofilm rate processes including nutrient uptake, growth rate, and biofilm removal. Because fluid shear is controlled independently of bulk residence time, researchers can isolate the effect of shear stress on biofilm development without confounding flow rate variables. The 20 removable slide coupons allow intermittent sampling for cell mass, cell number, and biofilm composition at defined time points throughout an experiment. Minimum biomass accumulates in the bulk fluid at short retention times, keeping planktonic cell counts low relative to the attached biofilm population. The BAR 1420 can be sealed for pathogenic biofilm studies, and its compact footprint makes it practical for bench-scale work.
Applications
The BAR’s primary use is biofilm evaluation in water and process fluids, with particular strength in applications where hydraulic shear is a critical experimental variable.
Drinking Water Research: The BAR is well established for evaluating disinfection efficacy in distribution systems, including comparisons between free chlorine and alternative disinfectants against attached versus suspended populations, assessment of disinfectant residual decay over time, and investigation of regrowth potential following treatment plant modifications. It is also used for long-term corrosion inhibitor studies, where the interaction between phosphorus-based inhibitors and microbial growth is a key concern.
BAR 1420 LJ
The Jacketed Laboratory Biofilm Annular Reactor adds a water jacket around the outer cylinder for temperature-controlled experiments. Recommended for studies where temperature is an independent variable or where elevated process temperatures need to be replicated.
BAR Slide Coupons
