03564nas a2200421 i 4500 20260819085215.0 271098s1982 th u m rtt 0| a1eng d .b10743583 AIT Thesis no.EV-82-25 Islam, Md. Serajul Treatment of tannery waste-effects of trivalent and hexavalent chromium Bangkok : Asian Institute of Technology, 1982 67 leaves : ill. Thesis ; no. EV-82-25 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development Thesis (M.Eng.) - Asian Institute of Technology, 1982 The 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. Tanning Waste disposal Samorn Muttamara, Chairperson Vigneswaran, S., Examination Committee Chongrak Polprasert, Examination Committee Belgium Government, Scholarship Donor Asian Institute of Technology. Thesis ; no. EV-82-25 Full-Text http://203.159.5.9/ait-thesis/detail.php?q=B21207 .b10743583 mnait x 240903 2 951012 m a x 0 mnait mnait mnarc 22 40 20 Barcode : 30050120655484 CREATED : 2014-05-02 RECORD # : i12756969 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050120225072 CREATED : 2016-04-05 RECORD # : i1296931x LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050121074693 CREATED : 2023-03-21 RECORD # : i13439558 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 123048 123048 0 0 0 0 MAIN MAIN mnait 2026-08-19 50.00 0 AIT Thesis no.EV-82-25 30050120655484 2026-08-19 08:52:16 4 2026-08-19 22 0 0 0 0 MAIN MAIN mnarc 2026-08-19 0 AIT Thesis no.EV-82-25 30050120225072 2026-08-19 08:52:16 2026-08-19 40 0 0 0 0 MAIN MAIN mnait 2026-08-19 50.00 0 AIT Thesis no.EV-82-25 30050121074693 2026-08-19 08:52:16 1 2026-08-19 20