As the modern society is rapidly developing and people become affluent in materials, many new chemical compounds in different forms of products (e.g., antibiotics, pesticides, detergents, personal care products and plastic goods) are produced, used, and disposed of to the environments. Some of them are persistently having a harmful impact on the environment and mimicking endocrine properties; in general they are present in the environment at low concentrations, so they are called organic pollutants. These organic micropollutants flow to sewage treatment plants via different routes. In this study, the generation characteristics, exposure pathways, detection levels, and environmental impacts of organic micropollutants were critically reviewed. In addition, currently available risk assessment methods and management systems for the compounds were reviewed. The United States Environmental Protection Agency (US EPA), for example, has monitored organic micropollutants and set the monitoring and management of some of the compounds as a priority. To effectively manage organic micropollutants in sewer systems, therefore, we should first monitor organic micropollutants of potential concern and then make a watch list of specific substances systematically, as described in guidelines on listing water pollutants in industrial wastewater.

The odorants from wastewater sludge treated with four different chemical oxidants, i. e., potassium ferrate, sodium hypochlorite, sodium permanganate, and calcium nitrate, were analyzed. The release of odorants from the treated sludge was not completely eliminated, only retarded, possibly due to the low one time doseof oxidants. In a comparison of the concentration profiles of methyl mercaptan and dimethyl sulfide, calcium nitrate was the best of the four different oxidants at reducing their emission. For methyl mercaptan, calcium nitrate gave the best result, while for dimethyl sulfide, potassium permanganate was found to be the best oxidant. From this study, it was found that the oxidation-reduction potential (ORP) would be an easy and inexpensive parameter for the monitoring of the release of offensive odors.

A wastewater treatment plant consists of unit processes designed to achieve specific waste reduction goals. However, offensive odors associated with the treatment processes are a constant source of public complaints. The purpose of this study was to statistically determine the process parameters that influence the formation of volatile sulfur conpounds (VSCs) in the secondary treatment system. A statistical model was developed to relate the process parameters to the formation of VSCs in this system. The model established that F{M ratio, sludge blanket depth and SSV60 were the dominant process parameters that would influence the formation of VSCs in the secondary sedimentation basin. This model provides a useful tool for plant engineers to predict and control the VSCs formation in an secondary activated sludge system.