Type of Document Master's Thesis Author Nash, Jeffrey William URN etd-08012012-040641 Title Characteristics and conditioning of anaerobically digested sludge from a biological phosphorus removal plant Degree Master of Science Department Environmental Engineering Advisory Committee
Advisor Name Title Knocke, William R. Committee Chair Novak, John T. Committee Member Randall, Clifford W. Committee Member Keywords
Date of Defense 1989-02-05 Availability restricted AbstractA study of the anaerobically digested sludge form a
full—scale biological phosphorus removal (BPR) plant (York
River Wastewater Treatment Plant, York River, Va.) was
conducted to determine the effects of BPR on sludge
characteristics and conditioning requirements. Data
collected from the plant indicated that both the total and
soluble phosphorus (P) concentrations in the anaerobically
digested sludge increased dramatically with the initiation
of BPR. Accompanying this increase in total P was an
increase in the total concentrations of magnesium and
potassium content of the sludge, supporting the observations
that these ions are co—transported with P during the
accumulation and release of P by P accumulating organisms.
The majority of the phosphate present in the pre- and post-
BPR anaerobically digested sludges was bound by calcium,
magnesium, and iron phosphorus precipitates including
hydroxyapatite, struvite, and vivianite. Calcium phosphorus
precipitates were the most prevalent in both sludges, but
the percentage of magnesium phosphorus precipitates
increased with the onset of BPR.
Cationic organic polymer conditioning dosages needed to
achieve acceptable sludge dewatering rates for the post—BPR
sludge were similar to those required by the pre-BPR sludge.
The cationic organic polymer used to condition these sludges
was ineffective in removing excess phosphate; therefore, the
addition of either one or both of the inorganic chemicals
ferric chloride and calcium hydroxide was required to remove
soluble phosphorus. Conditioning with either ferric
chloride or calcium hydroxide alone was not effective in
achieving acceptable dewatering rates; however, when used
together the chemicals produced acceptable dewatering rates
and soluble P removal from the post-BPR sludge.
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