Upflow Anaerobic Sludge Blanket System Research Articles

A Modified UASB Process Treating Winery Wastewater

During the last two years,twenty-seven bioreactors of upflow anaerobic sludge blanket(UASB) process were constructed and operated well to treat 3,300 m3/day of winery wastewater in six winery plants in Taiwan. Each UASB reactor was installed with an internal filter and a side-armed sludge settler to separate gas-liquid-solid effectively in 127 m3 of reactor volume.These six plants established good performance of UASB process with different organic loadings depending on different characteristics of the winery wastewater. Start-up performance of the modified UASB process in four winery plants was investigated.Bioactivity of anaerobic sludge in each UASB was evaluated by means of Biochemical Methane Potential (BMP)test. Biokinetics of Monod and Haldane models were employed to interpret the different sludge characteristics in terms of gas production rate. Scanning electronic microscopy also showed different morphology of sludge granules in three UASB systems.

Start-up of anaerobic bioreactors on high strength industrial wastes

Anaerobic filters, anaerobic fluidized beds and upflow anaerobic sludge-blanket (UASB) reactors were started up on two types of pharmaceutical waste; anaerobic fluidized beds were also started up on glucose, fruit processing, soft drink manufacturing and pharmaceutical wastes. Fluidized beds proved superior to UASB reactors and filters in COD removal capacity and pH stability during start-up, although methane production was greatest in the UASB systems. The industrial wastes proved recalcitrant to anaerobic conversion as they contained substances inhibitory to microorganisms but loadings of up to 7·5 kg COD m −3 day −1 could be applied with a COD removal of 78% achieved. The types of volatile acids produced in four of the units were found to relate closely to substrate composition.

Advanced Reactor Design, Operation and Economy

Of the high rate anaerobic wastewater treatment systems the UASB (Upflow Anaerobic Sludge Blanket) reactor has found the widest application. Therefore the attention with respect to design, operation and economy will be focussed on this reactor type. In designing a UASB reactor specific attention is needed for the GSS (Gas-Solids Separator) device and the feed inlet system. For soluble wastewater generally no phase separation is required. Only for wastewaters high in suspended solids pre-acidification in a separate acidification reactor can be beneficial. Increasing attention is given to the development of modified UASB systems, such as a combination of a sludge bed reactor and an anaerobic filter. Other possible modified UASB systems may be found in a FS (Floating Settling) UASB reactor, the EGSB (Expanded Granular Sludge Bed) reactor and the UASB IC (Internal Circulation) reactor. As many factors are involved in the costs of a UASB reactor, only some rough data on reactor costs are presented.

A comparison of an upflow floc (tower) digester and UASB system treating cane juice stilage

The anaerobic digestion of cane juice stillage in an Upflow Floc (tower) digester and an Upflow Anaerobic Sludge Blanket (UASB) system was compared. The use of a synthetic flocculant (Zetag 88N) in the Upflow Floc digester enhanced the retention of biomass and resulted in a significantly reduced start-up time compared to the UASB. The installation of effluent recycle on both systems substantially improved digester stability. Ultimately, there was no marked difference in the performance of both systems with the achievement of high space loadings, in excess of 22 kg COD m −3 day −1, and soluble COD removal efficiencies>95%.