碩士 / 國立高雄師範大學 / 生物科技系 / 105 / With the blooming of semiconductor industries, the large amounts of wastewater discharged from the production process of these industries have became an important issue for environmental regulators. Many studies have shown that the physio-chemical properties of some effluents from the industies was lower than Effluent Standards, but they still caused toxic effects to aquatic organisms. When such effluents were discharged directly into rivers, it may cause toxic effects to aquatic ecosystems and affect human health.
Therefore, the aims of this study were to determine the physio-chemical properties and toxic effects of effluents from three semiconductor industries (SI-A, SI-B, SI-C) and the discharge station (T), analyze major chemicals which are responsible for effluent toxicity, and access ecological risk of such chemicals to the river ecosystem using the USEPA ecological risk assement model. It is expected to provide management strategy for the semiconductor industry to improve effluent quality and protect river ecosystems.
The results showed that wastewater from SI-A caused high acute toxic effects to water fleas (Daphnia magna) and carps (Cyprinus carpio). After treating wastewater by wastewater treatment processes, the acute toxicity of the efflents decreased with the attenuation efficiency higher than 40%. The statistical correlation analysis showed that copper and zinc were the major chemicals responsible for toxicity of effluents and wastewater from SI-A. The acute toxicity unit (TUa) of effluents from SI-B, SI-C and T to water fleas and carps was mostly lower than 1.43 (Effluent Standards). Althought physio-chemical properties of all efflents was lower than Effluent Standards of semiconductor industries, the TUa of some effluents was higher than 1.43. It indicated that low levels of some chemicals in effluents still caused toxic effects to test organisms. Some physio-chemcial parameters of effluents from SI-B and SI-C were higher than those from SI-A, but less toxic effects were found for effluents from SI-B and SI-C. The effluent from T collected at the 15th week showed high acute toxicity, but its physio-chemcial properties is lower then Effluent Standards. It might be due to unknown chemicals causing toxic effects.
The results from toxicity tests of chemicals and raw materials showed that concentrations of copper and ammonia in effluents from T were higher than LC50 (Median lethal concentration) of copper and ammonia to water fleas. The discharges effluents from T without dilution might cause toxic effects to aquatic organisms.
The Spearman's correlation analysis using toxicity data and water quality of wastewater from SI-A and effluents from SI-A, B, C and T showed a significantly positive relationship between TUa of water fleas and copper (R = 0.692, p < 0.05). It indicated that copper was the major chemical responsible for toxicity of effluents.
According to Guidelines for Ecological Risk Assessment suggested by USEPA, the chemicals of potential concern in effluents were ammonia, copper and nickel. The ecological risk criterion were in the order: copper > ammonia > nickel. Percentages of species affected were in the order: ammonia > copper > nickel. The acute and chronic toxicity of these three chemicals were added together, respectively. It was estimated that after discharging effluents into the river ecosystem, approximately 50% of aquatic organisms have acute toxic effects and 98% have chronic toxic effects. Ammonia contributed the most toxic effects, followed by copper and nickel. Thus, it is better to reduce the use of raw materals containing ammonia and copper, or to improve the efficiency of wastewater treatment system to decrease concentrations of ammonia and copper in effluents in order to lessen their risk to ecosystems.
| Identifer | oai:union.ndltd.org:TW/105NKNU0111009 |
| Date | January 2017 |
| Creators | LIN, SHU-CHUN, 林淑君 |
| Contributors | TIEN CHIEN-JUNG, 田倩蓉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 115 |
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