As wastewater comes into a plant, one of the very first steps is to remove large solids. A bar screen is important for that reason. Despite ads, printed media, and other warnings that people stop flushing plastic wrappers, rags, baby wipes, and plastic applicators, it still happens.
When a wastewater treatment plant is intertwined with storm drains, twigs, leaves, branches, cans, bottles, and plastic bags get into the wastewater. Bar screens remove these items to prevent clogs and damage to wastewater equipment. However, there are always challenges with wastewater bar screen operations that need to be considered.
Six Common Challenges of Wastewater Bar Screens and How to Overcome Them
What are some of the most common challenges with the operation and maintenance of wastewater bar screens? There are six at the top of our list.
The Accumulation of FOG
Fats, oils, and grease, aka FOG, are an annoyance that wastewater treatment plant operators deal with regularly. When FOG clings to trash rake bars, it builds up and solidifies into a stuck-on mess. Talk to city officials about requiring grease traps in restaurants and commercial kitchens in your municipality. Grease traps catch FOG for easy removal and keep it out of sewer lines.
That will cut down on FOG, but it won’t remove it all. You need to degrease your bar screen regularly to keep it from creating clogs and slowing flow rates. Ask a wastewater treatment equipment specialist about the best screening materials for plants that get high quantities of FOG.
Clogs From Debris
Debris like branches, cans, bottles, and plastic bags are problems when they get stuck and reduce wastewater flow rates. While the role of a bar screen is to remove them, no system is foolproof. Items can get stuck and need clearing.
Prevent debris accumulation by checking that the bars in your screen are sized appropriately for the most common materials you have to remove. If you get a lot of bottles and cans because your system is connected to stormwater, you might find wider spacing is fine. But, you get a lot of plastic applicators and they slip right past wider bars, so you need spacing that’s better at catching the smaller items.
You can also look into bar rakes that automatically reverse if there is a jam. By going into reverse, it helps clear the items that caused the obstruction and ensures the system works efficiently and effectively.
Wastewater can be corrosive, and even stainless-steel construction is susceptible to corrosion over time. You can apply coatings to bar screens to limit the damage. Regular inspections of the bars to check for corrosion help alert you to problems before they become a major headache.
If your wastewater treatment plant is in an industrial area, talk to city officials about requiring factories to have industrial wastewater treatment plants and treat their water before releasing it to the sewer system.
Mechanical Wear and Tear
Wear and tear from regular use is bound to happen. With planned maintenance and routine inspections, you can catch damaged or worn parts before the damage becomes a major inconvenience. Make sure your wastewater treatment plant has the appropriate screens in place to prevent damage. Look for durable construction, too. You might find that composite parts last longer than metal or plastic ones.
Sand and grit also wear out components. A grit collection system is an essential part of a wastewater treatment plant, so make sure it’s part of your system.
Rags are a headache. Look into rag catchers placed before your bar screens to catch rags, baby wipes, pads, and other fibrous materials before they get into your bar screen. When they reach a bar screen, they can wrap around components and get snagged, which creates extra work for your maintenance team.
Weather and the Unexpected
Not every system is connected to a stormwater system, but some still are. The U.S. is working hard to get cities and municipalities to separate systems and come up with ways to help with unexpected rainfall that leads to flooding of storm drains and wastewater treatment plants.
When weather creates high flow rates, your system may not be prepared. Have protocols in place for weather events, power outages, or unexpected equipment breakdowns. Measures that automatically adjust flow rates and help avoid overworking bar screens are essential.
Setting up a lot of green spaces between sidewalks and roadways provides one way to use up water. Adding rooftop gardens, turning concrete lots into parks and playgrounds, and tree-lined streets all help keep stormwater from rushing to storm drains. It also helps lower the risk of erosion.
What Does a Bar Screen Do?
Think of a bar screen like an escalator. It has steps that travel upward from wastewater areas and collect items on the bars as the steps move upward. At the top of that bar screen, the items get raked into a collection bin for composting or incineration, and the steps go back down to the wastewater to repeat the process.
Tips for Keeping Your Equipment in the Best Shape
Once you’ve installed wastewater bar screens, you need a regular preventative maintenance plan in place. That includes regular inspections and procedures that ensure your employees focus on efficient bar screen operations.
While a bar screen and trash rake do a great job, you need to have someone monitoring the controls. The ability to check performance remotely helps a lot, but there still needs to be someone performing basic maintenance. Some of the things that require basic maintenance are:
- Adjust and clean solenoid valves
- Check and adjust brushes and scrapers
- Check roller chains for wear and adjust tension as needed
- Inspect and grease the bearings and rack and pinion gears, if needed
- Inspect the tracking system and tighten any loose fasteners
- Periodically check for heavier debris like rocks
- Testing the motor for vibrations and amperage
When you have new wastewater bar screens installed, ask the experts what the best maintenance plan is and if there are any special considerations. Lakeside Equipment’s expertise with water treatment solutions dates back to 1928, so your municipal or industrial wastewater needs are addressed by a professional team with the insights you need.
We recommend two bar screens. The Raptor Multi-Rake Bar Screen excels at removing inorganic solids with low headloss. The FalconRake Bar Screen, also from Raptor, has a heavy-duty design that stands up to severe conditions and doesn’t rely on lower bearings, bushings, guides, or sprockets for minimal maintenance. Ask Lakeside Equipment about the pros and cons of these bar screens and find the right equipment for your plant’s needs.