81    ANOXIC SELECTOR FOR FILAMENTOUS BULKING
CONTROL, BOD REMOVAL, AND NITRIFICATION OF
PAPER MILL WASTEWATER
Allan J. DeLorme, Project Engineer
Shin Joh Kang, Partner
Christopher J. Englert, Project Engineer
Charles D. Fifield, Project Manager
McNamee, Porter & Seeley
Ann Arbor, Michigan 48108
INTRODUCTION
A finish paper mill which produces a single coated label stock and a proprietary laminated playing
card stock discharges a wastewater high in suspended solids, organic matter, and ammonium-
nitrogen. Newly imposed effluent limitations will require secondary treatment for BOD removal and
nitrification. The pilot study was undertaken to establish the basis of design for treating the waste to
levels consistent with these new effluent limitations.
WASTEWATER CHARACTERIZATION
The mill discharges a waste stream with characteristics given in Table I. The wastewater is currently
treated in a Dissolved Air Flotation (DAF) unit for suspended solids removal. The effluent is then
split seasonally for partial discharge to a receiving stream and land application via spray irrigation.
Considerable variability exists in the wastewater characteristics, especially with respect to suspended solids and ammonium-nitrogen. This highlights the need for equalization, efficient primary
clarification and nutrient supplementation prior to biological treatment.
Due to the nature of plant operations, especially the routine use of biocides, zinc and cyanide
compounds, it was also suspected that compounds potentially toxic to activated sludge organisms may
be periodically present in the wastewater.
PILOT STUDY DESIGN
The pilot study was carried out in two phases: 1) toxicity screening; and 2) testing.
The toxicity screening was carried out due to the concerns stated previously and consisted of a series
of batch experiments performed at McNamee, Porter & Seeley laboratories. The results of this phase
would subsequently influence the design and operation of the pilot-testing.
The pilot-plant was operated to establish design parameters for full-scale biological treatment.
Since paper mill wastes have been known to cause significant bulking problems, the "selector"
concept was tested. Selectors are relatively small chambers where influent wastewater is mixed with
return activated sludge for a short period before entering the aeration basin. The basis behind this
technology is explained in more detail later.
MATERIALS AND METHODS
Selectors were constructed by connecting two polypropylene bottles in series with tygon tubing.
Each bottle maintained a 500 mL volume of mixed liquor and was mixed using a magnetic stirrer.
Aeration tanks were 57 liter rectangular Plexiglas containers partitioned into three segments with
fiberglass walls to achieve plug flow. Aeration was achieved by inserting diffusion stones into each
section.
44th Purdue Industrial Waste Conference Proceedings, © 1990 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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