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Effect of suspended solids concentration and filament type on the toxicity of chlorine and hydrogen peroxide to bulking activated sludge

1987; Wiley; Volume: 2; Issue: 1 Linguagem: Inglês

10.1002/tox.2540020105

0884-8181

Chang‐Womkim, Ben Koopman, Gabriel Bitton,

Chromium effects and bioremediation

Abstract Toxic inhibition of three communities of filamentous microorganisms by chlorine and hydrogen peroxide was investigated in relation to the total suspended solids concentration of bulking acitvated sludges. The filament communities studied were dominated by type 1701, Sphaerotilus natans , and the combination of type 021N and Thiothrix spp., respectively. Activity of filamentous and gross biomass was assessed separately using the malachite green‐INT (MINT) test. The effectiveness of toxicants was characterized in terms of the concentration required to inhibit 50% of microbial dehydrogenase activity (IC 50 ). IC 50 s were found to be proportional to total suspended solids concentration. Values for filamentous biomass were generally lower than those for gross biomass. Relative sensitivity (ratio of gross IC 50 to filamentous IC 50 ) did not vary significantly over the practical range of total suspended solids concentraton. This parameter was unaffected by the nature of the toxicant in S. natans and type 021N/ Thiothrix dominated sludges, but was toxicant specific in type 1701 dominated sludge. Overall, S. natans and type 1701 were the least sensitive of the filament types studied. Bulking caused by these organisms has been successfully cured by toxicant addition in numerous past instances. It is therefore expected that type 021N, Thiothrix , and most other types of filamentous bulking can also be controlled by this technique.