MODIFIED MEMBRANE BIOREACTOR CAN PRODUCE CLEAN PROCESS WATER FOR REUSE AND REDUCE SOLIDS DISPOSAL COSTS
Abstract:Membrane technologies are applied today in several industrial facilities to enable effluent reuse, water recycling or to replace “end of pipe treatment” with cost competitive recycling alternatives. The Zee Weed® Membrane Bioreactor has been used successfully in a variety of industries, as well as municipalities looking for water saving initiatives.
A textile company was evaluating several conventional treatment technologies in an effort to minimize waste disposal costs. The plant, amongst the lowest water users in its group, decided to explore the applicability of the Zee Weed® membrane bioreactor and reduce the concentrations of the main constituents below levels considered acceptable for water reuse. Chemical pretreatment technologies were considered inapplicable, mainly due to very high colloidal type suspended solids varying from 2,000 to 4,000 mg/L. COD and BOD levels in the untreated residuals were 25,000 mg/L and 10,000 mg/L respectively.
A pilot plant integrating Zenon's Zee Weed® membrane technology was tested over a period of 3 months for feasibility, process limitations, backwash frequency, and design parameters. The pilot system confirmed the proposed membrane flux of 6.7 gfd (maintained at a trans-membrane pressure of about 1.5 psig), as well as the need for monthly cleaning. The system provided consistent removal efficiencies higher than 99 percent on TSS, COD and BOD respectively. Treated effluent with COD < 500 mg/L, BOD < 20 mg/L, and TSS < 2 mg/L was produced after a one month acclimation period.
The bioreactor MLVSS level was maintained close to 12,000 mg/L. Levels above 12,000 mg/L reduced the membrane flux and required more frequent cleaning of the modules. Overall economical benefits could result mainly from diverting 50 to 75 percent of the waste to internal reuse, rather to final disposal. Land application of the biosolids is still the most economical option of management. This project is an example of how the use of innovative technology can change a pure expense to a highly desirable value added product: cheep process water.
Document Type: Research Article
Publication date: January 1, 2004
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