42    ANAEROBIC AND AEROBIC TREATMENT OF POTATO
PROCESSING WASTEWATER: CASE STUDY
Robert C. Landine, Manager
Environmental Engineering Division
Stephen G. Bliss, Senior Environmental Engineer
Graham J. Brown, Senior Environmental Engineer
Albert A. Cocci, Senior Environmental Engineer
ADI Limited
Fredericton, New Brunswick
Canada
INTRODUCTION
This paper describes the operation and results after some four years of operation of an anaerobic-
aerobic treatment facility located at New Annan, PEI, Canada, which treats the wastewater from a
potato processing plant. The paper also mentions the results of a pilot plant study initially conducted
to verify proposed design criteria prior to final design. Key physical dimensions and data, along with
design values, are furnished in the paper.
Biogas is recovered and burned in engines which drive alternators to produce electricity. More than
enough electricity is produced to satisfy the needs of the waste treatment facilities, and any excess is
exported to the food processing plant which supplied the wastewater.
The anaerobic effluent is polished in an extended aeration activated sludge plant. Final effluent is
discharged into an estuary at the head of Malpeque Bay.
Day-to-day operating supervision of the treatment plant is provided by ADI Limited, retained by
the owner of the plant, Northeast Energy Services Limited.
BACKGROUND
The original wastewater treatment system was constructed in the late '60s and consisted of screening
and primary clarification followed by an extended aeration system and a polishing aerated lagoon;
Figure 1 presents a schematic of this system. The wastewater being treated was generated by a potato
processing plant; the plant also processes peas during the summer for approximately four to six
weeks.
The sludge removed from the primary clarifier consisted mainly of potato solids, along with a small
amount of soil particles. It was either thickened by a vacuum filter into a cake, which was used as a
cattle feed, or pumped to sludge ponds located on site.
The effluent from the primary clarifier flowed by gravity to an aeration basin that contained an
integral clarifier. Aeration was initially supplied by two, 75 hp compressors feeding air to two types of
aeration devices, i.e., Helixors™ and perforated tubing. The compressors also supplied air to a series
of air lift pumps, in the integral clarifier, that returned the sludge to the aeration basin. There were no
provisions to waste sludge from this system. The effluent from the integral clarifier flowed by gravity
to a large polishing pond (Lagoon #1B) prior to being released to the Barbara Weit River, which flows
into Malpeque Bay, located on the northeast side of Prince Edward Island.
The two, original 75 hp compressors were rated to deliver 3000 scfm at 7 psig. A third compressor,
rated at 125 hp and capable of delivering 3,000 scfm at 7 psig, was later added to increase the aeration
capacity. Also, to reduce the load on the Barbara Weit River, the outfall was moved downstream, into
the estuary of Malpeque Bay.
An anticipated increase in potato production and wastewater flow led the Prince Edward Island
government (owners of the original system) to approach ADI and request a proposal on upgrading
46th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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