Investigation of Chemical Phosphate Removal from an Oxidation Ditch by Field Evaluation

Kim, Seung-Hyun; Baumann, E. Robert

Environmental Engineering Research 1997;2(3): 207-216.

Seung-Hyun Kim¹^†, and E. Robert Baumann²

¹Civil Engineering Department Kyungnam University
²Bolton & Menk, Inc.

Corresponding Author: Seung-Hyun Kim ,

Received: July 17, 1996; Accepted: April 17, 1996.

ABSTRACT

The phosphate removal capacity of an oxidation ditch with and without alum addition was examined using field evaluation in this study. An oxidation ditch serving 5,000 people was selected for this purpose. O-P and T-P concentrations in the plant influent and effluent were monitored every week over a 1-year period to determine the phosphate removal capacity of an oxidation ditch without chemical addition. The monitoring results showed that the oxidation ditch removed 30 % of the incoming T-P. Phosphate removed by the ditch was comparable to that by an ordinary activated sludge system The study operated by full plant and pilot plant scale experiments also showed that T-P concentration in the plant effluent could be reduced to less than 1.0 mg/1, which is an imaginary discharge limit of phosphate, by adding alum into secondary or tertiary treatment The alum addition increased the amount of sludge, but did not affect the BOD removal efficiency of the plant The sludge problem could be handled by wasting more sludge from the plant Based on Al/T-P molar ratio, it was found that phosphates could be removed more efficiently by adding alum into secondary treatment than into tertiary treatment.

Keywords: phosphate | oxidation ditch | alum | secondary treatment | tertiary treatment