Baffles are found all over the place, in a wide array of industries, applications, and shapes. Not only are baffles often used in water treatment and storage; they can also be found in architecture, acoustics, chemistry, chimneys, and even submarines. In principle, a baffle is a barrier used to obstruct or restrain a flow of a particular matter, or energy (like sound waves), from moving in a certain direction. These can be used in order to minimize reverberation, redirect water flow, or hide from sonar.
Underwater Baffles
When it comes to water, baffles are used to control and divert water flow within ponds, water treatment reservoirs, cooling systems, large tanks, and a wide variety of other applications.
In water treatment plants, baffles are placed in order to lengthen the amount of distance that the water has to travel before exiting the treatment system. This can be done through alternating windows in the baffles, or through open gaps. These are often placed on opposite sides, forcing the water to travel the longest path out. Slowing down the water as it moves through the system increases its overall retention time, and therefore its treatment time.
The amount of time that water spends in a particular system is referred to as HRT or Hydraulic Retention Time. Greater HRT offers more opportunities for chemicals to be treated, and sediments have more time to settle. HRT in a tank is determined by dividing the volume of the tank in gallons by the flow rate, or: HRT (hours) = (tank volume) / (flow rate) gph.
This reduces the overall TSS and BOD (biological oxygen demand). TSS refers to total suspended solids, or the measure of particles and sediment suspended within the water. BOD is biochemical or biological oxygen demand and refers to the amount of oxygen being required by decaying organic matter or waste from the water. Suspended solids can contain chemicals, toxins, and hard metals trapped within the material.
Utilizing baffles in this way can also prevent short-circuiting, where water escapes from the main flow of water and reaches the end of the system without adequate HRT in order to be properly treated.
If the water flow is being used as a cooling mechanism, baffles are used to redirect flow in order to maximize circulation and contact time to assist in heat transfer. Cool water flow is given a longer path to follow and forced closer to the motor or other source of heat. Baffles may also be used to separate intake and outtake flows, of either water or air. This ensures heat is continuously pushed out from the system, and new cooler air or water is allowed in.
Sometimes, baffles are used as turbidity curtains to force sediment to settle before entering a waterway. You’ll often find these around construction or industrial zones where a lot of sediment is pulled into the water via runoff. Baffles can also be used to divert flows away from high-erosion areas, or to eliminate dead zones within a body of water or tank. Dead zones are places where water escapes from the current and sits stagnant outside of the flow.
Floating Baffles
Baffles can come in many different shapes and forms. Floating baffles are held atop the water with a floatation device, usually made of foam, where a reinforced geomembrane skirt hangs down. Within a tank, these are attached to the walls or floors, while baffles found in open water are typically attached to the ground or stationary buoys with ballast chains and anchors. Some baffle curtains allow water to pass through via windows or open panels, creating serpentine paths for the water to travel while being guided by the baffles. Other kinds of baffles also include a long skirt, like in the case of silt or turbidity curtains. These can be permeable or impermeable, depending on the conditions and their intended use.
Booms
Other baffles have shorter skirts, especially those meant to capture solids or liquids that have gathered on top of the water’s surface, like in the case of an oil spill. These are typically referred to as booms, and only hang a few inches beneath the water’s surface. Longer curtains, or full-size baffles, can reach numerous feet into the water in order to control sediment or alter waterflow.
Attached Baffles
Some baffles are permanently attached to the walls or floors. These can be geomembranes, concrete, steel, or a variety of other materials. These are especially popular within small tanks or reservoirs, or when needing to define a small area, like diving intake and outtake flows or protecting pumps and valves from sediment.
