Solids settling is a critical aspect of most water treatment applications. Whether a tank utilizes a form of advanced solids settling through the use of tube settlers or plate settlers, or if the basin has a simple open clarifier design, solids that amass on the floor must be periodically removed. One way to achieve this sludge collection is by draining the tank and manually sweeping the basin floor. However, this is a labor-intensive process that requires the tank to be completely drained each time in order to properly clean the floor. Luckily, there are more practical solutions available to help maintain a basin floor free from excessive sludge accumulation.
Traditional System Designs
While solids removal system designs vary, they all serve the same goal: to remove sludge from the basin floor. Some vacuum-type systems utilize a hose design to collect solids. These systems are guided on a track along the center of the basin floor and are driven by a cable. Sludge is collected through pipes with orifices and are channeled out by a hose.
Alternatively, some systems do not employ a hose at all. Instead, these systems rely on a telescoping main header. This header travels along the basin’s length. These systems also use pipes outfitted with orifices that cover the tank width and extend to the tank walls. There is often no track required for these systems as the main telescoping header allows the system to stay centered. However, they do typically require a cable-driven system to move the header back and forth.
A third type of system that is commonly seen in sludge removal is one that uses pipes with orifices but doesn’t contain moving components. The pipes on this system are instead arranged in an array throughout the basin floor. While this design appears to be more of a departure from other systems, particularly because there are no moving parts, it still serves the save purpose: to vacuum up sludge and water in the area surrounding the pipes.
Common System Issues
In our extensive travels over the years to water treatment plants around the world, we have received feedback from many plant operators about some of these sludge removal systems. Many have claimed that, while these systems initially performed well, they would eventually experience decreased efficiency and require frequent maintenance. Many grievances were related to clogging issues and excessive amounts of water being wasted during operation. Why is it so common for these systems to lose efficiency over time?
Many header pipe systems rely on a series of smaller holes/orifices to intake sludge and water. These holes, and the pipes themselves, gradually develop an accumulation of sludge inside. Because these pipes are rigid, it is unlikely that these accumulated solids will break off on their own once adhered to the sidewalls of the pipe(s). This buildup results in less sludge and water being taken in than originally designed as the inside diameter of the pipe is effectively reduced. This means that the system must work longer and harder to perform as it previously had – eventually creating the need for additional maintenance.
This situation is analogous to clogged arteries. As plaque accumulates in our arteries, blood flow is restricted. This creates a narrower passage for blood to move through. The heart must then work harder to achieve the same level of blood flow and puts added stress on the body. If buildup is not properly maintained, there will eventually be a complete blockage and system failure.
Traditional systems are also notorious for wasting excessive amounts of water. Header pipes are usually positioned a few inches above the basin floor, so the floor’s compacted zone of solids cannot be fully cleaned. This causes the system to collect a higher percentage of water. These systems also usually operate while traveling both forward and backward across the floor – intaking water and solids for the entire time they are in motion.
SedVac™ Sediment Removal System
Brentwood’s SedVac Sediment Dredge System was specifically designed to address these issues. SedVac features unique, triangular-shaped wings that focus solids to the wings’ back point before discharging the effluent. This results in a significantly higher concentration of solids and a smaller amount of water discharge. Due to its robust efficiency and wipers on the back of the wings, SedVac effectively cleans the entire basin floor after one pass across the basin length. The valves can then be closed and additional solids removal on its return to the home position is not needed.
This has proven to be an optimal method for sludge removal and is the primary reason we can confidently say that SedVac removes a higher percentage of sludge while removing less water than other systems on the market.
In a pilot study going head-to-head with a traditional header pipe system, SedVac removed twice as much sludge in half the time and wasted fifty percent less water. Check out the full results in our blog: Comparing Sludge Removal Systems For Water Treatment Plants.
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