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Treatability Assessments

Online Primer

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There are two basic options for conducting biological treatability tests: batch respirometer tests and continuous reactors. 

Batch respirometer tests give indication of the biodegradability of wastewater constituents, show the extent of biodegradation, and give an indication of potentially toxic conditions.

Operating bench-scale reactors under continuous or semi-continuous feed conditions can provide more realistic indications of actually achievable in the field treatability.  Tests typically involve a number of reactors each operated at different hydraulic and solids retention times.  The units must be operated for sufficient lengths of time to insure steady-state regime with respect to both wastewater feed and biomass growth.  Such tests can allow for microorganism acclimation, which can occur slowly, and can show cumulative effects of toxic substances that may be in the wastewater or may accumulate as biodegradation products.  For instance, ammonia released during the biodegradation of high-strength protein wastewater can inhibit nitrification.

The decision to conduct semi-continuous of continuous bench-scale reactors tests in addition to batch respirometer tests is somewhat subjective and depends to some extent on the intended used of the data.  If the data are to be used for design of new processes, then bench-scale reactor tests have significant value because they give biological growth and kinetic parameters that considerably reduce the risk of failure.  If the tests are conducted to evaluate operating problems with existing processes, then batch respirometer tests may have more value because a larger number of variables can be tested in a short period of time.








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