| Summary: | 碩士 === 國立中山大學 === 環境工程研究所 === 107 === Wastewater treating efficiencies of the Food-processing factories accompanied with various choices of biological systems. The factories cause serious problems to the environment due to the high concentration of organic matter chemical oxygen demand (COD).
Two TYPES systems (TYPE1/TYPE2) were set up. TYPE1 system is aerobic system combine with ASP (Activated sludgea procese) and MBR system (TYPE1 ASP+MBR). TYPE2 system consisting of UASB (up-flow anaerobic sludge blanket) followed by ASP (Activated sludgea procese) and membrane bioreactor (TYPE2 UASB+ASP+MBR). After running for 30 weeks, the scope of application of UASB, ASP and MBR operating conditions is found. Therefore, measurment the change of membrane differential pressure (TMP) and membrane (FLUX) let us understand the formation of membrane filtration and fouling behavior.
Results of different biological treatment systems showed that the TYPE1 system has about 90% COD removal rate and TYPE2 UASB combine with ASP and MBR about 98% COD removal rate. In addition, TYPE1 SS removal rate is 91% and TYPE2 SS removal rate is 83%.
Comparison of membrane flux and differential pressure, TYPE1 show that membrane flux is reduced to 103 LPM and membrane pressure is raised to 3650 mmaq during six~seven weeks. However, TYPE2 membrane flux drops to 108 LPM and the membrane pressure rises to 3500 mmaq during ten weeks.
Different membrane cleaning results were found between two TYPES. The different cleaning results indicated that the membrane fouling layer in the TYPE1 contained more inorganic components than TYPE2.
The overall COD removal efficiency of the TYPE2 system was higher than the TYPE1. However, the TYPE2 showed a much lower SS removal efficiency than the TYPE1.
This result confirms that fouling materials presented in the two TYPES are different. As reported in literature, NaOCl is mainly used to remove organic foulants, while citric acid mainly removes inorganic foulants. It can be expected that more inorganic fouling occurred in the TYPE1 than TYPE2.
TYPE1 has faster membrane fouling such as Inorganic fouling / smaller particle
…,etc. than TYPE2 under sub-critical flux operation. Once it got fouled due to operation at/above its critical flux, the membrane of the both TYPES could not return to its initial stable performance anymore.
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