In this study, two microbial bioassays, i.e. the commercialized Microtox® test and the specific oxygen uptake rate (SOUR) method, are used to assess the individual response of existing wastewater treatment facilities in several high-intensity pollution industries. Initially, the microbial toxicity of manufacturing effluents from a petrochemical industry are assessed. The toxicant sources in the manufacturing effluents are then investigated to develop the baseline of the waste reduction in the manufacturing processes. According to these results, the amount of aldehyde group contributes the majority of the microbial toxicity in the wastewater. Therefore, the abatement of the aldehyde wastewater may be the most effective factor to release the loads for following wastewater treatment facilities.
To control the discharge sources to the treatment facilities (WWTP), WWTPs with high-intensity pollution industries and public WWTPs in three industrial districts are further evaluated with their effluents to determine the primary contributor of toxicants. From the effluent toxicity results, the relationship between organic loads and toxic effluents exhibits a positive conjunction in the high-intensity pollution industries. If these industries can enhance their removal efficiency of organic compounds in the pretreatment system, the toxicity of their effluents can be effectively reduced. Consequently, the following treatment facilities can perform more efficiently to satisfy their needs.