Activated sludge process operational problems

Operational problems to activated sludge process can cause low soluble BOD removal and poor settling of the sludge in the secondary settling tank. The reasons for these problems could be because of unusual... 

A biosensor for nitrite [24] was recently proposed for monitoring nitrite concentration in activated sludge exposed to oxic/anoxic cycles. The biosensor contains bacteria reducing only N02 into N20, which is subsequently monitored by a built-in electrochemical sensor. Up to 90% of the response is obtained in about 1 min, and the detection limit is around 5 mg L1, a concentration sufficient for treatment process monitoring. Unfortunately, the maximum operational lifetime of the N02 biosensor is 6 weeks and some problems may occur with time. 

Isomerization processes developed slowly because of the low demand for higher octane numbers and operational problems with aluminum chloride, the first catalyst to be developed. Despite high activity at 115-120°C, aluminum chloride has the major disadvantages of the formation of sludges and acid corrosion of equipment. 

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