AWWA MTC95043

Powdered activated carbon (PAC) is a commonly used adsorbent in potable water treatment (29% of the 600 largest municipal water treatment facilities were using PAC in 1986). PAC is an effective adsorbent due to its high surface area and surface chemistry and is quite effective at removing a variety of matter. Included in the list of matter that PAC is competent in removing is natural organic matter (NOM), synthetic organic compounds (SOC), volatile organic compounds (VOC), metals, chlorine, biochemical oxygen demand (BOD) and hydrocarbons. Thus, its use extends to applications such as advanced treatment of municipal wastewaters, industrial wastewater and hazardous waste treatment. In a typical application, PAC is added directly to water in the rapid mix unit and removed via flocculation and settling. Another configuration, which is the particular process by which the slurries considered in this study are produced, consists of an ultrafiltration (UF) unit to which PAC is added, recycled and periodically wasted with membrane backflush water. This process results typically in concentrated suspensions of waste of 0.1-5 g/l. There are a number of options for the treatment of these slurries. This paper presents an innovative pressure driven membrane approach. The novelty of this approach lies in the manner in which a shear is induced tangential to the face of the membrane which permits it to treat flows with very high concentrations of solids. The shear force has a scouring effect which slows membrane fouling. The shear is generated by rotating hollow disk membranes at a high rate in a closed pressurized vessel. In this paper a description of the process and pilot unit constructed for testing the approach are given. Preliminary work on modeling the fluid dynamics of the rotating membrane system is presented. The results from this modeling effort are used to establish a basis for optimizing the process variables. Data on membrane performance in treating concentrated suspensions of PAC are presented.

Product Details

Published:

01/01/1995

ISBN(s):

0898678153

Number of Pages:

12

File Size:

1 file , 360 KB