Akademik Veri Yönetim Sistemi
JOURNAL OF ENVIRONMENTAL ENGINEERING, cilt.130, sa.11, ss.1289-1300, 2004 (SCI-Expanded)
The influence of four industrial wastewater types (organic chemical, dye, leather, and winery industries) on the exopolymeric substances (EPSs) constituents [protein, polysaccharide, and deoxyribonucleic acid (DNA)] and physicochemical properties of floes (contact angle, surface charge, and bound water) was determined. Four laboratory scale activated sludge systems were used; they were fed with real wastewaters and were operated continuously under steady-state conditions. The EPS analysis showed that between 70 and 80% of the extracellular organic material could be attributed to protein. The proteins in the bound form were quantitatively greater than the soluble protein form in winery industry floe EPSs. The soluble protein ratios were higher than bound protein ratios in organic chemical, dye, and leather industries floes. Lower amounts of protein and high DNA content were found in the EPS floes grown on wastewaters containing more complex substrates (organic chemical, leather, and dye). Changing the wastewater from chemical, leather, and dye to that of winery industry resulted in an increase in protein and a decrease in DNA level of floe EPSs. The sludge surface of winery industry floes were less hydrophobic (small contact angle) and more highly negatively charged compared to chemical, dye, and leather industry floes. A higher sludge volume index (SVI), an indication of poorer settleability, was associated with both small amounts of EPS and protein and a hi-h amount of DNA. Both high hydrophilic and negatively charged surfaces corresponded to lower levels of SVI and good settling properties. The results of this study demonstrated that wastewater type influenced the EPS composition and physicochemical properties of sludge. The surface properties (surface charge, contact angle, and bound water) and composition of EPS, apart from the carbohydrate content, governed the settleability of sludge and were important in controlling the SVI.