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.

By Kwabena Osei, MsCE

In an industry where alternative sediment and nutrient removal practices are increasingly sought, it is imperative that engineers and regulators know precisely just how efficient various Best Management Practices (BMPs) are. For many years, field testing has been the preferred method for evaluating different structural stormwater treatment systems. However, many unsuccessful or inconclusive field testing exercises have been carried out on structural BMPs over the past few years leading scientists and engineers to conclude that field testing is fraught with many obstacles and challenges that are difficult to eliminate, as well as potentially producing results that are not necessarily representative of the performances of both proprietary and non-proprietary stormwater management practices.

By Prof. Bob Andoh

By Robert Y.G. Andoh and Adam Neumayer

Membrane technology is an innovative, compact solution to the age-old wastewater treatment problems of effluent quality and footprint. Membranes, which combine clarification, aeration and filtration into a single process, are noted for their ability to consistently deliver a high quality effluent in a cost-effective manner in the confines of a small footprint.

Although membrane bioreactors (MBRs) offer many advantages, the membranes are sensitive to abrasive materials, such as fine grit which can erode the equipment to the point where it no longer functions. Additional pretreatment measures are required to provide membrane plants with a higher level of protection from fine grit.

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.