| Summary: | 碩士 === 國立中山大學 === 環境工程研究所 === 107 === The grinding wastewater produced during manufacture of semiconductor contains a large amount of fine particles, which often causes the concentration of suspended particles in the water to rise and is not easy to settle,increasing the difficulty and cost of the following treatment technologies. The pharmaceutical pollution is also becoming an important environmental issues in these decades. This study aimed at the silicon-containing grinding wastewater, using chemical coagulation pretreatment technology to increase the size of the silicon particles, followed by the subsequent filtration treatment such as candle filtration, membrane filtration, or centrifugation, etc., to remove those particles with a larger size from the water. The particles are removed, and the slag residue and grinding wastewater is effectively recovered and the water flux is increased. The results showed that in the pretreatment during coagulation by using ferric sulphate as the additive,the optimal operating conditions included a dosage of 100 mg/L, a reaction pH of 7.0, and an appropriate alkalinity controlled. The diameter of particles were efficiently increased after treatment. The size range arose from tens to hundreds of nanometers to between 2,064 and 7,132 nm after pretreatment.In the latter filtration, regardless of the use of centrifugation, membrane filtration, or candle filtration, it is effective to remove large particle size particles in water.The removal was effective as the effluent silicon concentration was below 5 mg/L. If precipitation was applied before filtration, the effect of centrifugation or membrane treatment seems to be limited however,the operational loading of the following steps may be reduced. With the candle filtration being considered, the additional precipitation was a plus for particle removal by increasing the lifetime of the membrane and enhancing the quality of the treated water. Overall, the coagulation pretreatment with the candle filtration effectively treated the silicon-containing wastewater. The recovery of silicon from the sludge is another advantage of this technology, as the sludge moisture content was below 40% and the silicon content was about 50%.
As the pharmaceutical treatment, coagulation is also a common technology for municipal wastewater and drinking water treatment. Graphene oxide is a promising adsorbent for removing pollutants from water. This study also explores the feasibility of adding graphene oxide-iron oxide composite S2.5 to remove metformin, a pharmaceutical and an emerging pollutant during coagulation for treating the sewage from National Sun Yat-sen University. The results showed that when the S2.5 does was 60 mg, the metformin removal rate was 47.4%. When the pH was 8, the removal rate was 51.2%, and the NDMA formation potential was 16.0 ng/L. It was found that metformin in the water could be partially removed （~50%）at neutral pHs （e.g., pH 6-10）.
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