Street Sweeping To Improve Water Quality

By Author: Lucy Carter
Total Articles: 102
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Street sweeping can be an effective water quality management practice. Stormwater managers have demonstrated a renewed interest in street sweeping due to improvements in road sweeper technology and because of the fact that highly urbanized areas don't allow for the implementation of many structural controls.

Streets are a significant source of water contaminants. One kilogram of street dirt contains an average of three million CFU (colony forming units) of fecal coliform bacteria, residential areas being larger sources of bacteria than industrial and commercial sites. Studies indicate that 3/4 of the fecal coliform bacteria content in residential runoff water comes from the streets and that both streets and parking lots are critical sources of many contaminants in commercial and industrial areas. Most runoff originating from streets is moderately toxic and has been shown to adversely impact the environment. Aquatic organisms have higher contaminant concentrations and the diversity of aquatic organisms decreases as a result. The importance of ridding streets of contaminants to prevent water pollution is clear. Targeting ...
... streets and parking lots is also the most cost-effective way of controlling water quality in many areas.

There are three different types of road sweepers on the market today: mechanical, vacuum-assisted and regenerative air. Mechanical sweepers work by removing dirt from the street with a rotating broom and using a conveyor system to empty it into a hopper. This is the most common type of road sweeper, but the downside is that it only removes coarse particles (those larger than 400 μm) and doesn't pick up fine particles. Under the best of conditions, 30 percent of solids can be removed from streets using mechanical sweepers, which achieve optimal performance in areas with distinct wet and dry seasons. Due to the abrasive action of mechanical sweepers they can actually increase the concentration of fine particles in the streets.

Vacuum-assisted sweepers are a combination of a mechanical sweeper (a rotating broom, for instance) with a high-power vacuum. Some vacuum-assisted sweepers use a water spray to suppress dust while others operate dry with a continuous filtration system. Wet vacuum-assisted sweepers remove 40 to 82 percent of particles smaller than 10 μm and dry vacuum-assisted sweepers remove nearly 100 percent of such particles. Overall, vacuum-assisted sweepers are about twice as effective as mechanical sweepers.

Regenerative-air sweepers employ a mechanical sweeper to lift dirt and forced air to dislodge remaining particles. The dirt gets caught by a high-power vacuum with a continuous filtration system that recycles the air. This type of road sweeper is able to remove 31 percent of particles finer than 10 μm.
Oliver Newton is the owner of Priority Plant, a leading supplier of new and used road sweepers in the UK.