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 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

Many developers and municipalities have invested in filtering systems to meet the US EPA mandate for reducing these storm water runoff problems. Their experiences reveal a fundamental flaw in the design of conventional “down flow” filtration. The capital investment in these immense systems — sometimes spanning whole football fields in size — is tremendous and regular maintenance is cost-prohibitive.

By Prof. Bob Andoh

By Dr. Bob Andoh

For years municipalities around the globe have invested in stormwater treatment systems to remove pollutants from runoff. Whether they are used for stand-alone treatment or as pretreatment devices to keep our infiltration bays from clogging, these “sedimentation devices” have an important role in stormwater treatment. Yet a troubling problem has emerged and become more apparent: many proprietary treatment systems don’t hold what they catch. When flows increase, previously captured pollutants can re-suspend and discharge right out of the system. Moreover, many communities are not aware of this phenomenon — known as “washout” — leaving them with a false sense of security about the ability to keep their waterways clean.