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 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. 

Upflow storm water filters provide an effective and economical alternative to addressing the short comings of downflow filters.  

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.

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 

Communities with CSO issues lack adequate funds to undertake the required level of capital and operations and maintenance investments without a potential near doubling of local rates and fees. Conventional systems are costly and this, coupled with the funding constraints and issues of affordability, clearly highlights the need for more innovative, cost-effective and sustainable “alternative approaches” to resolving the current collection systems and wastewater treatment needs and challenges.

The use of satellite treatment systems located within collection systems provides the scope for resolving some of the challenges in urban wastewater infrastructure provision in a cost-efficient manner as demonstrated in Saco, Maine, and Columbus, Georgia. Monitoring and operation of these full scale systems has confirmed that high-rate processes such as vortex separator, either on its own or followed by compressed media filter, can be used to remove the gross solids and the lighter fraction of fine particulates while passively optimizing in-system storage.