| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 83 === The purpose of this study was to develope an automatic control
sequencing batch reactor (SBR) for chemical precipitation of
heavy metals fromelectroplating wastewater. A capacity of 2
cubic meters pilot-scale SBR facility was installed at a
plating factory whose wastewater mainly contain Cr,Zn and Fe
with the concentration in about 150 mg/l, 450 mg/l and 120 mg/
l, respectively. For a long term on-site test run, the
treatment efficiency for heavy metal removal was investigated
and the operatingstrategies of SBR were evaluated. The results
indicated that the effluent concentration of heavy metals,
including Cu, Zn, Cr and Fe, could be treated to as low as to
meet the National Effluent Standard of 1998 no matter what
operating strategies were employedin this study. There are
several discrete operational periods were established during
one cycle for each sequencing batch treatment of the plating
wastewater.The periods were fill/pH adjustment/rapid mix, slow
mix (flocculation), settle, draw, and idle/waste sludge in a
time sequence. Idle and/or waste sludge could be eliminated
depending on requirements of the treatment problem. When sludge
accumulated in the reactor to a high concentration resulted in
slow settlingvelocity or poor effluent quality, a portion of
sludge should be wasted. Under normal operation condition, the
SBR could serve as storage and thicking ofsludge in addition to
chemical reaction. The experimental results showed thatthe
thickened sludge concentration could be up to 6% of TS. For
better sludge storge and thickening, it is suggested that the
height of drainage nozzle would be located at 1/3 - 1/2 of the
effective height from the bottom of SBR.
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