TY  - SER
AU  - Islam,MdSerajul
AU  - Samorn Muttamara,
AU  - Vigneswaran,S.
AU  - Chongrak Polprasert,
ED  - Belgium Government,
TI  - Treatment of tannery waste-effects of trivalent and hexavalent chromium
T2  - Thesis
PY  - 1982///
CY  - Bangkok
PB  - Asian Institute of Technology
KW  - Tanning
KW  - Waste disposal
N1  - 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
N2  - 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
UR  - http://203.159.5.9/ait-thesis/detail.php?q=B21207
ER  -