AWWA ACE65259

Given the benefits derived from membrane treatment of water and wastewater, interest in usingmembranes is growing throughout the world, and at an ever increasing rate. As expected, the focushas been on the benefits of the product water (permeate) side of the system, but the systemsidestreams (concentrates) bring their own special set of issues. As with any new technology orapplication, there are benefits and liabilities. Membrane separation is a non-destructivetechnology; the membranes merely concentrate the rejected pollutants in a sidestream. Severaltypes of membranes are used in water and wastewater treatment, and the sidestream from eachtype contains pollutants in different concentrations.What impacts do these pollutants have on the wastewater treatment plant (WWTP) and thecollection system and how does a system operator assess these impacts? This paper provides anoverview of a completed WateReuse Foundation Research project to asses these impacts. The paper briefly reviews the literature search, datacollection methods (user web-based survey of water and wastewater plant operators), utilitypartner interviews, and a review of issues such as corrosion, recycling and concentration ofpollutants in the wastewater, process inhibition, WWTP effluent quality, and impacts of thepollutants on the receiving streams.The research also identified many of the water balance impacts that can significantly increase theconcentration of residuals entering a wastewater system. Water utilities often sell water tooutside customers who do not return it as wastewater to the utility's collection and treatmentsystem, which creates an imbalance that may cause additional stress on both the wastewatertreatment plant and the receiving stream.To account for all these variables, two models were developed. Black & Veatch's researchpartner, the University of North Carolina at Chapel Hill (UNC) developed a model to predict theconcentration of specific chemicals in concentrates reaching a WWTP. Black & Veatchdeveloped an over arching system wide mass balance model. The B&V model comprises all ofthe elements of separation processes that account for generation of the concentrate at the sourceand 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 andin the waste solid streams. Multiple concentrate sources can be included. Both models are neededfor the guidance manual that has been prepared as part of this project. There are points of entryissues/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 anoverview of this work and detailed guidance on the use of the models including tips on how tocollect necessary input data and how to structure the model for a specific community's collectionand treatment system(s).In short, this paper presents a summary of the just completed WateReuse Foundation (WRF) studytitled Impacts of Membrane Residuals on WWTPs. Includes 7 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/01/2007

Number of Pages:

62

File Size:

1 file , 3.5 MB