By Prof. Bob Andoh

Across the United States, wastewater treatment plant operators face a common problem that threatens the effectiveness of their plants. It’s grit. Grit erodes mechanical equipment and accumulates in channels and process chambers causing capacity and operational problems. Grit accumulation in primary and secondary process basins diminishes a plant’s performance, reduces its treatment capacity, and increases operational and maintenance costs. Grit is a continuous and common problem, which impacts treatment plants worldwide. However, the solution which will most effectively remove it can vary by plant.

By Professor Robert Andoh

Burgeoning commercial and industrial development is putting increased pressure on drainage systems. Land and vegetation act as a natural filtration system during storms. The conversion of open space to impervious materials such as roads, buildings, and parking lots increases the volume of runoff and the risk of downstream flooding. Worse, too fast an influx of water into the drain overtaxes combined sewage systems, causing untreated sewage to spill out into waterways.

Until recently, most developers and municipalities in the U.S. relied on end-of-pipe solutions such as large detention tanks, deep tunnel storage systems, and high rate treatment facilities to combat urban flooding problems. However, these large, structurally intensive systems are extremely costly to purchase and to maintain.

To alleviate these challenges, many in the U.S. are now looking to an alternative approach long relied on in Europe and the U.K. More than 16,000 vortex flow controls, also known as vortex “valves”, are installed around the world to manage water flow in stormwater storage schemes, stormwater sewers, combined sewers and wastewater treatment plants. These novel devices are useful for many applications, including inlet control and stormwater storage.

By Robert Y.G. Andoh

Throughout the world, thousands of stormwater pollutant removal systems are being installed in an effort to prevent watercourses from being polluted. As supply has risen to meet demand, a variety of proprietary, chamber-based systems have emerged, including hydrodynamic separators, which are designed to settle out and store sediments and associated pollutants, preventing them from being discharged to the natural environment.

However, recent research suggests that some systems may not be as effective as might be claimed. Some systems are subject to “washout” or “scour,” whereby captured and stored pollutants are flushed from a system during extreme wet weather.

By Prof. Bob Andoh

By Robert Y.G. Andoh, Mike Faram and Dave Scott

Water industry officials throughout Europe – and in a growing number of municipalities in North America – tend to think of vortex valves as a novel technology for outlet flow control on a stormwater detention system. Most of these 17,000+ valves installed around the world are, in fact, implemented on stormwater detention schemes because use of a valve can reduce the required storage volume by up to 50% while still meeting the maximum discharge requirement. But vortex valves actually have many other uses in stormwater, wastewater and combined sewer systems. These versatile devices tackle a number of other problems, including erosion control, re-oxygenation of water and flow equalization in wastewater treatment plants.