This property was reserved by
raed64
on
October 10, 1999
I'm 29 years old,
from Copenhagen,DK.
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My research is on membrane bioreactors for wastewater treatment. A membrane bioreactor (MBR) is a combination of a biological treatment process, such as
activated sludge, and solids separation by means of semipermeable membranes (ultrafiltration or microfiltration).
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Membrane separation bioreactors
MBR process employs ultra- or micro-filtration membranes for biomass retention in the bioreactor. Complete mineralization of influent organic matter is
facilitated by maintaining high biomass concentrations (>10, 000 mg Mixed Liquor Suspended Solids l-1) and the retention of high molecular weight solutes.
This negates the need for secondary treatment. Furthermore, the membrane allows solids retention time to be separated from hydraulic retention time.
This MBR process is attractive for situations where long solids retention times are necessary to achieve the removal of pollutants within a wastewater
Such membrane processes, whether in combination with aerobic or anaerobic reactors, can be operated with the membrane unit submerged in
the reactor vessel or as a side-stream unit. In the former configuration, the cost of recirculation of liquor to a separate membrane unit and the return of
solids to the bioreactor is avoided. Tubular, hollow fibre, and flat-plate membrane configurations with pore sizes ranging from 0.1 mm to 0.3 mm
have been employed. In addition to the membrane characteristics, permeate flux depends on factors such as suspended solids concentration, cross-flow
velocity, temperature, transmembrane pressure drop, surface fouling and the extent of concentration polarisation.
Commercial aerobic separation MBR processes exist for the treatment of many wastewaters, including industrial, domestic, landfill leachate and grey-
and black-wastewaters. Since 1991 this process has been treating an oily wastewater at a General Motors facility in the USA with a 94 percent removal
of influent COD and a significant reduction in ammonia, fats, oils, greases and phosphorous. The reactor size is 287 m3 and the loading rate averages
6 kg COD m-3 d-1.
Anaerobic treatment also has been successfully coupled with membrane separation.
Treatment of degradable industrial wastewaters by anaerobic processes not only has the advantage of low sludge production but also produces energy. Employing
membrane separation enables the retention of slow growing methanogens and produces a high quality effluent.
The Anaerobic Digestion Ultrafiltration (ADUF) process from South Africa is one of the most commercially successful of this type of process, using
Membrateck tubular polysethersulfone membranes operated at low pressures (500 kPa) and situated externally from the anaerobic digester. A
commercial 2,610 m3 ADUF plant treating maize processing effluent at COD of 3 mg l-1 and operating at a HRT of 120 h, averages 97 percent organics
removal and a permeate flux ranging from 8 to 37 l m-2 h-1. The combined capital and operating cost for a 1,500 m3 d-1 ADUF plant treating a brewery
wastewater were estimated at US$ 0.6/m-3 of treated effluent.
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