| Summary: | 博士 === 國立臺灣大學 === 環境工程學研究所 === 101 === The immobilized bioprocess (IBP) was investigated for the removal of organic carbon and ammonia nitrogen from wastewater. Two wastewaters (a food industry wastewater and a composite industrial wastewater) were investigated, one containing high concentration (810~1,306 mg/L) and the other medium concentration (279~531 mg/L) of chemical oxygen demand (TCOD). Three entrapped mixed liquor suspended solids (EMLSS) (3,000 mg/L、5,000 mg/L and 9,000 mg/L) in the IBP and two hydraulic retention times (HRT)(12 h and 24 h) were employed representing different surface loading and volume loading factors. IBP provides high sludge retention time (SRT), enabling improved removal of COD and ammonia nitrogen. The results showed 88~92% and 87~93% removals of soluble COD (SCOD) and ammonia (NH4+-N), respectively, from the food industry wastewater, when the surficial removal rate and volumetric removal rate in the IBP were 0.011~0.056 kg COD/m2-d and 2.34~11.58 kg COD/m3-d, respectively. For the composite industrial wastewater, removal of SCOD and NH4+-N were 59~80% and 41~67%, respectively, when the surficial removal rate and volumetric removal rate were 0.0048~0.016 kg COD/m2-d and 1.01~3.40 kg COD/m3-d, respectively. The results further show stable removals of COD and NH4+-N, albeit decreasing with decreasing HRT and MLSS. IBP facilitates simple operation and good effluent quality without requiring sludge recycling.
The immobilized membrane bioreactor (IMBR) was investigated for the removal of organicmatter and its membrane fouling condition in treating food processing wastewater. The IMBR contains 5,000 mg/L entrapped mixed liquor suspended solids with hydraulic retention time of 24 h. The advantages of IMBR include high sludge retention time, improved removal of COD, ammonia nitrogen, and reduced membrane fouling frequency with much less production of soluble microbial products (SMPs). The results showed that the IMBR was an effective organic matter removal system because it achieved 96~97% removal of COD consistently. The concentration of total SMP in the IMBR was measured at 47mg/L which included 25 mg/L of protein and 22mg/L of carbohydrate. Steadily, approximately 33% of carbohydrate and 11% of protein were rejected by the microfiltration (MF) membrane. For this reason, it was concluded that carbohydrate poses a more significant impact on membrane fouling through formation of cake/gel layer than protein. Further, various operating conditions during membrane filtration were experimented which included continuous and intermittent filtration, aeration and non-aeration, and with fiber filter (FF) as pretreatment. It was discovered that while adding an additional FF filtration before MF might improve suspended solid retention, SMP was instead discovered to be the major cause of membrane fouling. In addition, aeration in the membrane tank could significantly improve membrane performance by scouring lightly attached particles from the membrane surface.
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