A survey of filamentous organisms at the deer Island treatment plant
Abstract The Deer Island Treatment Plant (DITP) treating both domestic and industrial wastewater, has a peak flow capacity of up to 1270 million gallons per day (MGD) (3342 m3 min−1). The DITP contains a Pilot Plant, which consists of two identical pure oxygen activated sludge treatment trains, each with a maximum capacity of 1 MGD (2.63 m3 min−1) to simulate the maximum flow of the full size facility. This study documents the community of filamentous organisms living in the activated sludge under various operational conditions in the Pilot Plant. Sixteen types of filamentous organisms were identified. The major filamentous organisms present in the Pilot Plant were Type 1701, Type 0041, Sphaerotilus natans, Microthrix parvicella, and Nocardia sp. Nocardia sp. was quite dominant in the early stages of the experimental period during high ambient temperatures (summer), indicating that temperature is one determining factor in the distribution of Nocardia sp. Thiothrix sp. was very sensitive to the dissolved oxygen (DO) level, with low DO values favoring the growth of the organisms. Microbiological observations made during the start‐up and stable operation of the full‐scale secondary treatment plant (maximum capacity 780 MGD) are also reported. No dominant filamentous species existed during the start‐up period. Type 0803 and Type 1701, indicators of low oxygen level for the applied food to microorganism ratio, confirmed the low DO conditions of activated sludge tanks.
Isolation and characterization of filamentous bacteria present in bulking activated sludge
SummarySeveral types of filamentous microorganisms were observed and identified in samples of poorly settling (bulking) activated sludge. The major types encountered and the frequency (percentage) of appearance in the total of all treatment plants sampled were: Eikelboom type 0041 (60), type 1701 (45), Haliscomenobacter hydrossis (35), type 021N (30), Thiothrix spp. (20), and Sphaerotilus natans (20). Isolation techniques and culture media were developed and used to recover 42 axenic strains of filamentous bacteria from sludge samples collected. The isolates were identified as strains of Thiothrix, Beggiatoa, S. natans, and Eikelboom types 021N, 1701, 0041, and 0803. Nutritional and differential characterization of the bacteria was important to the differentiation of groups which could not be easily distinguished on the basis of morphology. Although certain treatment plant operating parameters (organic loading) seemed associated with the presence of specific filamentous organism types, possible interaction among factors precluded definite establishment of a cause and effect relationship for most of the treatment plant characteristics and organisms observed.
On a New Subclass of p-Valent Close-to-Convex Mappings Defined by Two-Sided Inequality
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