Integrated pulp & paper mill with an aerated stabilization basin built in 1969 was so full of solids that the mill was having several problems: degradation of treatment performance, inability to access aerators for maintenance, safety concerns, high energy usage, severe short circuiting. The decision was made that #1 Lagoon must be cleaned out. Evaluation of all types of removal, dewatering, transportation and disposal were evaluated. Geotube® containers appeared to provide the most economical approach. Because Geotube dewatering technology offered such economic and environmental benefits and since it was relatively new technology to the pulp & paper industry the mill decided to start with a pilot study. The pilot study consisted of four geotextile containers and was done in the fall of 2001 to provide answers to questions along with an approach for the full scale project. The pilot study confirmed anticipated expectations and provided such information as obtainable effect from variations of flows, solids, chemistry, filling rates and dewatering rates. The pilot study also provided information of anticipate percent solids of dewatered sludge, filtrate condition and odor impacts. The full scale project moved ahead utilizing Geotube technology meeting all expectations and realizing additional benefits not originally planned.
Key Words: dewatering, Geotube container, lagoon, remediation, waste.
A large multi-national paper company operates a coated paper and kraft pulping facility in Upper Peninsula of Michigan. The mill's kraft hardwood facility 45 Metric tons per day of market pulp and pulp slurry to several paper machines producing about 1,785 metric tons per day of coated book and publication papers. To manage the mill's 1.46 x 10s liters per day usage they constructed, in 1969, a 12 hectare area Aerated Stabilization Basin (ASB) system built in 1969 (Fig. 1).
The ASB system consists of Primary clarification, aeration basin, activated sludge basin, secondary clarifier, unaerated settling lagoon, and tertiary treatment prior to discharge into the river. Because of the solids build-up in #1 aeration lagoon over the past 35 years numerous operation problems existed along with environmental issues that would create significant problems. Investigation into all removal, dewatering, transportation, and disposal options were looked at by mill, corporate engineering, and consulting companies. Detailed profiles of the lagoon were done to confirm the amount of solids present.