Given the benefits derived from membrane treatment of water and wastewater, interest in using
membranes is growing throughout the world, and at an ever increasing rate. As expected, the focus
has been on the benefits of the product water (permeate) side of the system, but the system
sidestreams (concentrates) bring their own special set of issues. As with any new technology or
application, there are benefits and liabilities. Membrane separation is a non-destructive
technology; the membranes merely concentrate the rejected pollutants in a sidestream. Several
types of membranes are used in water and wastewater treatment, and the sidestream from each
type contains pollutants in different concentrations.
What impacts do these pollutants have on the wastewater treatment plant (WWTP) and the
collection system and how does a system operator assess these impacts? This paper provides an
overview of a completed WateReuse Foundation Research project to asses these impacts. The paper briefly reviews the literature search, data
collection methods (user web-based survey of water and wastewater plant operators), utility
partner interviews, and a review of issues such as corrosion, recycling and concentration of
pollutants in the wastewater, process inhibition, WWTP effluent quality, and impacts of the
pollutants on the receiving streams.
The research also identified many of the water balance impacts that can significantly increase the
concentration of residuals entering a wastewater system. Water utilities often sell water to
outside customers who do not return it as wastewater to the utility's collection and treatment
system, which creates an imbalance that may cause additional stress on both the wastewater
treatment plant and the receiving stream.
To account for all these variables, two models were developed. Black & Veatch's research
partner, the University of North Carolina at Chapel Hill (UNC) developed a model to predict the
concentration of specific chemicals in concentrates reaching a WWTP. Black & Veatch
developed an over arching system wide mass balance model. The B&V model comprises all of
the elements of separation processes that account for generation of the concentrate at the source
and all of the elements of separation processes that account for transport/fate through the WWTP.
The result is a model to predict the concentration of components in the effluent at the WWTP and
in the waste solid streams. Multiple concentrate sources can be included. Both models are needed
for the guidance manual that has been prepared as part of this project. There are points of entry
issues/impacts from the membrane reject streams and there are more global quality issues/impacts into and out of the WWTP.
The Guidance Manual, to be made available by the WateReuse Foundation in 2007 provides an
overview of this work and detailed guidance on the use of the models including tips on how to
collect necessary input data and how to structure the model for a specific community's collection
and treatment system(s).
In short, this paper presents a summary of the just completed WateReuse Foundation (WRF) study
titled Impacts of Membrane Residuals on WWTPs. Includes 7 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 3.5 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 62 |
| Published : | 06/01/2007 |
