Title page for ETD etd-08012012-040641

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
  • Sewage
Date of Defense 1989-02-05
Availability restricted
A 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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