ODOR EMISSIONS OF LARGE WWTPS - SOURCE STRENGTH MEASUREMENT, ATMOSPHERIC DISPERSION CALCULATION, EMISSION PROGNOSIS, COUNTERMEASURES - CASE-STUDIES

Annoyance caused by malodors emitted by wastewater treatment plants is a most important problem in the FRG today. The legal regulations existing today in Germany are strict and under discussion with the aim to state even more restrictive stipulations. In the field of "odor-caused annoyance" it is necessary to use test persons as a detector to achieve results that correctly characterize the phenomenon to be assessed. In the case of odor, it is necessary to understand the basic concepts of sensoric measurement in order to assess the results correctly. In addition, special sampling techniques are necessary. On the emission side, olfactometric measurement is required. Olfactometric measurement programs were carried out on several wwtp's giving a picture of the emission strength of large wwtp's. On the immission side, field inspection with direct judgement by the test persons is used. If immission prognoses are required, it is necessary to do atmospheric dispersion calculations combining source strength data and meteorological data in order to gain a somehow correct prediction of future immision situations, If immission standards are exceeded, countermeasures, reaching from simple operational measures to covering and waste a-ir treatment, may be necessary.