44    ANAEROBIC TREATMENT OF AN ELECTRONICS
MANUFACTURING GLYCOL SOLVENT WASTEWATER
James W. Morris, Senior Consultant
Woodard & Curran Inc.
Portland, Maine 04102
Andre L. de Vegt, Manager of Technology
Paques, Inc.
Exton, Pennsylvania 19341
Mark A. Burke, Chief Wastewater Operator
Sprague Sanford, Inc.
Sanford, Maine 04073
INTRODUCTION
Sprague Sanford, Inc. is a manufacturer of electronic components in southern Maine. They
employ about 1,200 people producing high quality capacitors. Part of their process requires the •
use of ethylene glycol. Costs to have this material removed from the site were very high, rising,
and the haulers available for pickup service were growing unreliable. Sprague wanted a new system to dependably address this wastestream while avoiding the high costs and uncertainty they
were facing. A characterization study revealed that approximately 100 gallons per day at 350,000
mg COD/L needed to be handled by the new system. Nearly all of the COD present was as waste
ethylene glycol solvent. However, product quality concerns made recovery and reuse of this
wastestream too difficult. A wastewater treatment technology screening and economic analysis
indicated that the upflow anaerobic sludge blanket process (UASB) was well suited for this application.
Unlike the raw wastestream, the effluent from such a system could be readily accepted by the
local POTW when combined with all the other flows from this manufacturing facility. The low
design loading of only 300 pounds COD and low flows meant that the system needed would be
very small. Justifying a pilot study in this situation would be very hard.
The ethylene glycol molecule is very simple and was known to be amenable to aerobic treatment at low concentrations. Batch anaerobic treatability tests showed the wastestream produced
by Sprague to be very amenable to anaerobic treatment as well. With these results and the vendor's previous successful treatment of high strength wastestreams, the decision was made to install a full scale UASB with a volume of 24 m3 (6,300 gallons). A CBI Walker BIOPAQ® unit
was chosen.
SYSTEM DESCRIPTION
Details of the UASB technology are widely understood and will not be addressed. A conceptual schematic showing the system components and configuration installed is detailed in Figure
1. Glycol wastewater flows from the production area to a 1,000 gallon holding tank for flow
equalization. Wastewater then enters a mix tank where caustic soda and a nutrient solution are
added to the raw influent and recycle return flow mixture. The caustic dosage was controlled in
response to a pH probe located in the mix tank. Nutrient addition was paced to the influent flow
pump and adjusted to the influent COD concentration by the operator. The reactor contents were
held at 35°C by a heat exchange unit on the recycle return line.
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50th Purdue Industrial Waste Conference Proceedings. 199S, Ann Arbor Press. Inc., Chelsea. Michigan 48118.
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