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005 20260819085215.0
008 271098s1982 th u m rtt 0| a1eng d
035 _a.b10743583
099 9 _aAIT Thesis no.EV-82-25
100 1 _aIslam, Md. Serajul
245 1 0 _aTreatment of tannery waste-effects of trivalent and hexavalent chromium
260 _aBangkok :
_bAsian Institute of Technology,
_c1982
300 _a67 leaves :
_bill.
490 1 _aThesis ;
_vno. EV-82-25
500 _aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development
502 _aThesis (M.Eng.) - Asian Institute of Technology, 1982
520 _aThe purpose of this research work was to study the effect of trivalent and hexavalent chromium on the activated-sludge treatment of tannery waste. A complete characteristics analysis and treatability study of tannery waste was performed. Since Cr-III toxicity is a direct function of Cr-III in soluble form and solubility is a function of pH alkalinity and waste characteristics; particular emphasis was given on the study of the solubility of trivalent chromium. In case of Cr-VI, an effort was made to investigate the uptake of hexavalent chromium by activated sludge for consequent removal. Results of the research work showed that 81% of the COD can be removed from tannery waste by activated-sludge process in a detention time of 12 hrs. The trivalent chromium toxicity is due to its soluble form. At any influent Cr-III concentration, the available soluble Cr is less than 4 mg/t and the rest is retained with MLSS in the reactor in precipitated form (pH= 6.8 - 9.0). A daily addition of 100 mg/t of Cr-III for 10 days with a gross accumulation of 576 mg/t (28.8% of MLSS on dry wt. basis) of precipitated Cr-III and 4 mg/t of soluble Cr-III, the laboratory activated-sludge units showed no loss in efficiency. The hexavalent chromium toxicity is a function of only MLSS concentrations at and above F/M ratio of 0.25. A metal to biomass ratio, i.e. Cm/Cx; ratio of 0.005, is the safe limit for Cr-VI. Below F/M ratio of 0.25, the toxicity is a function of both substrate and MLSS concentrations and increases with the decrease of substrate and MLSS concentrations. A maximum uptake of 45 mg of Cr-VI is possible with 2 gm of MLVSS.
650 0 _aTanning
_xWaste disposal
700 0 _aSamorn Muttamara,
_eChairperson
700 1 _aVigneswaran, S.,
_eExamination Committee
700 0 _aChongrak Polprasert,
_eExamination Committee
710 2 _aBelgium Government,
_eScholarship Donor
810 2 _aAsian Institute of Technology.
_tThesis ;
_vno. EV-82-25
856 _3Full-Text
_uhttp://203.159.5.9/ait-thesis/detail.php?q=B21207
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