摘要:

The authors investigated the rejection of six synthetic organic chemicals (SOCs) in a potable water source by a nanofiltration membrane softening process. Each SOC was studied separately for one month—which was subdivided into four recovery periods. The four largest‐molecular‐weight compounds (chlordane, heptachlor, methoxychlor, and alachlor) were completely rejected by the membrane. Ethylene dibromide, the lowest‐molecular‐weight compound studied, was not rejected by the membrane, whereas dibromochloropropane was partially rejected. Mass balances indicated that SOC recovery decreased as SOC molecular weight (MW) increased, which suggested that the three largest‐MW SOCs had been adsorbed by the membrane. The percentage of SOC rejection increased as MW increased, and the rejection of inorganic solutes increased as MW and species charge increased. No effect on solute mass transfer of any solutes resulted from membrane feed‐stream velocities, which were estimated to vary from 0.19 to 0.52 fps.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1992.tb07287.x

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

The organics and inorganics rejection characteristics of eight types of reverse osmosis membranes operating on a source of highly colored groundwater in Orange County, Southern California, were determined. All eight membranes were capable of removing color from groundwater. Additional long‐term testing of four membranes—two brackish water (BW) and two softening–nanofiltration (NF) membranes—was carried out at relatively high flux rates and increased recovery. These membranes produced a color level of 3 pcu or less, far below the current drinking water standard of 15 color units. Trihalomethane formation potential was effectively removed by both types of membrane. The NF membranes were more energy efficient than the BW membranes.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1992.tb07288.x

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Numerical simulations and experimental work for evaluating transport mechanisms for colloidal foulants in pressure‐driven membrane systems are discussed. A model for concentration polarization is used to explore the role of ionic strength in determining the distribution of dissolved humic materials near a rejecting membrane. Particle trajectory theory predicts that there should exist a critical particle size above which particles will not deposit on the membrane. For conditions typical of ultrafiltration and microfiltration, which operate in laminar flow and utilize an inside‐out geometry, this critical particle diameter is likely to be in the range of 10–50 μm. Qualitative evidence, based on measurements of permeate flux, supports the theoretical minimum in diffusive back‐transport of particles predicted to occur for particles near 0.1 μm in size.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1992.tb07289.x

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Hoping to save money and to reduce solid waste, water utilities are evaluating various alternatives for the disposal of clarifier sludge containing 30 to 50 percent hydrated aluminum hydroxide. In this work, the authors studied a selective, simple‐to‐operate alum recovery process using composite membranes made of fine particles of chelating polymers entrapped in thin sheets of porous polytetrafluoroethylene. Laboratory studies using the sludge from the Allentown (Pa.) Water Treatment Plant showed that alum can be recovered selectively without any significant carryover of organic matter (trihalomethane precursors), manganese, or other heavy metals into the recovered alum. The composite membrane was quite robust and durable and exhibited a high affinity toward dissolved aluminum.

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1992.tb07290.x

出版商:Wiley    

年代:1992

数据来源: WILEY

ISSN:0003-150X    

DOI:10.1002/j.1551-8833.1992.tb07291.x

出版商:Wiley    

年代:1992

数据来源: WILEY