No matter what you’re intending on baffling -- the material, design, and placement of your baffle walls will entirely depend on your conditions and purposes. In smaller tanks, wall or floor mounted, solid curtains or walls will serve well to separate treatment chambers or intake and outtake flows. In a small backyard pond where you want to divert flow or protect a particular area in order to control turbidity/separate fish, a floating baffle with a hanging skirt may be the best fit.
If maximizing HRT is the goal, carefully designed baffle installations force water to spend more time in a specific stage before it moves on to the next. A tank that's 20'x 40' for example, can represent 800' of passage with 1' wide channel, an increase of 20x over an unbaffled straight path. This can lead to significant savings when it comes to land use and construction costs vs an 800' tank.
When it comes to the baffles themselves, what are you hoping to control? A perforated turbidity curtain can capture solids and sediments, certain curtains are equipped with special mesh in order to catch even the smallest particles while still allowing water to pass through. Diverting water flow will of course require a water-proof material with the weight and length to prevent water from escaping underneath or over the baffle. However, in rivers and coastal systems, curtains should be prevented from reaching the bottom in order to protect the fabric from being caught in sediment. If a complete watertight seal is needed for your purposes, the curtain will need to be strong enough to handle the flow rate, any suspended solids, and build-up of sludge along the floor of the reservoir or tank.
Considerations:
- Chemical composition of the wastewater
- Oftentimes, wastewater is full of abrasive chemicals that can corrode or leach into porous materials. It’s a good idea to test your water if you intend to reuse it or release it back into surface or groundwater. This can give you some idea of what’s in your water, and which chemicals may be present within your system
- Some materials used in traditional curtains or walls, like concrete, PVC, etc., soak in chemicals and release them back into the water through a process called leaching. Others easily corrode if allowed to come in contact with abrasive material over a long period of time.
- Water that is going to be used on foods, plants, or other forms of human-consumption needs to be stored and transported via plant and food-safe materials. This includes ensuring that chemicals toxic to humans aren’t being leached into the water.
- Liners and baffles that are safe for holding water intended for human consumption are approved by independent parties approved at the local and state level. The majority of BTL’s polyethylene products, including baffle curtains, are approved at the highest level by the international NSF. This means they are the safest form of material that can be in contact with potable water and won’t leach or absorb dangerous chemicals.
- Exposure to ultraviolet light
- Some materials break down underneath prolonged sunlight, degrading due to the exposure to UV light and radiation. If your baffles are going to be exposed to sunlight, even if covered by water, UV-resistance will play a large part in the durability of your curtains.
- Temperature range
- Particularly hot or cold water can cause direct damage to materials that come in contact with it. Some materials are better or worse at transferring heat and may conduct warmth to anything surrounding it if particularly conductive.
- If ice or freezing may occur within your design, this can have major impacts on any material that the water touches. Water expands when it freezes, meaning that tanks, walls, or pipes may be damaged by ice forming. Concrete or other porous materials will form cracks or breaks if water within freezes and expands inside.
- Hydraulic flows
- How strong is the water flow going to be? Do you want to completely divert the flow’s direction, or contain another material within or on top of the water? A stronger flow will require heavier grade curtains, reinforced edges, and a stronger anchoring system.
- Are you dealing with any outside current? Curtains placed with the intent to allow water to pass through will want to place themselves parallel with the current and make considerations to prevent submergence of the floatation itself.
- Temporary or Long Term Forces
- Will your baffles be exposed to wind? Ice and snow? Are there corrosive sediments or chemicals in your water that would eventually eat away at the material? Even short-term storms will require a maintenance and inspection plan.
- What are the dimensions of the lagoon?
- What area are you hoping to enclose, and how big of a space must be filled by the curtain? This will involve the depth of your lagoon or tank, the slope of the edges, and the length between each end of each panel. This will help you choose the size of your curtain, and how long they must be.
- Will your curtains use windows or gaps to redirect flow?
Reinforced polyethylene (RPE) is a popular option within pond liners, baffles, or other applications. It is lightweight, easy to install, and can be manufactured in very large single panels so that seams are not required. RPE’s reinforcing scrim layer prevents both tears and punctures, and the qualities of polyethylene (HDPE and LDPE) make the material naturally resistant to UV exposure. BTL Liners’ AquaArmor products are fish, plant, food, and human safe (AquaArmor is NSF-6 certified for containing potable water.)
BTL Liners specializes in manufacturing baffles curtains to custom specs based on your needs and design. We can fabricate a variety of configurations that account for the special needs of even the most complex installations. Whenever necessary, we’re able to fabricate custom panel lengths, variations in skirt depths, anchoring or ballast setups, extra reinforcement for heavy duty applications, and even use materials that offer extreme resistance to UV or chemical degradation. UV resistance is a critical factor if your installation needs to remain viable for a long stretch, or if you plan to store it and use it again.
For help with any of the above questions, BTL Liners has years of experience working with engineers to produce curtains with the right sizes, the right densities, and the right configurations for a virtually unlimited range of situations. Our highly qualified fabrication team produces your curtain in-house to meet the highest standards in the industry, with precisely welded seams, strict quality checks, and carefully packaged and labeled panels. Our state-of-the-art facility and dedicated team allow us to maintain the highest standards in speed of delivery, customer service, along with industry leading products.
